Journal articles on the topic 'Ocean observational systems'
To see the other types of publications on this topic, follow the link: Ocean observational systems.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Ocean observational systems.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Davis, Russ E., Lynne D. Talley, Dean Roemmich, W. Brechner Owens, Daniel L. Rudnick, John Toole, Robert Weller, Michael J. McPhaden, and John A. Barth. "100 Years of Progress in Ocean Observing Systems." Meteorological Monographs 59 (January 1, 2019): 3.1–3.46. http://dx.doi.org/10.1175/amsmonographs-d-18-0014.1.
Full textAbstract:
Abstract The history of over 100 years of observing the ocean is reviewed. The evolution of particular classes of ocean measurements (e.g., shipboard hydrography, moorings, and drifting floats) are summarized along with some of the discoveries and dynamical understanding they made possible. By the 1970s, isolated and “expedition” observational approaches were evolving into experimental campaigns that covered large ocean areas and addressed multiscale phenomena using diverse instrumental suites and associated modeling and analysis teams. The Mid-Ocean Dynamics Experiment (MODE) addressed mesoscale “eddies” and their interaction with larger-scale currents using new ocean modeling and experiment design techniques and a suite of developing observational methods. Following MODE, new instrument networks were established to study processes that dominated ocean behavior in different regions. The Tropical Ocean Global Atmosphere program gathered multiyear time series in the tropical Pacific to understand, and eventually predict, evolution of coupled ocean–atmosphere phenomena like El Niño–Southern Oscillation (ENSO). The World Ocean Circulation Experiment (WOCE) sought to quantify ocean transport throughout the global ocean using temperature, salinity, and other tracer measurements along with fewer direct velocity measurements with floats and moorings. Western and eastern boundary currents attracted comprehensive measurements, and various coastal regions, each with its unique scientific and societally important phenomena, became home to regional observing systems. Today, the trend toward networked observing arrays of many instrument types continues to be a productive way to understand and predict large-scale ocean phenomena.
2
Peres Teixeira, Carlos Eduardo. "THE DATA WE NEED FOR THE OCEAN WE WANT TO PREDICT: A BRAZILIAN PERSPECTIVE." Arquivos de Ciências do Mar 55, Especial (March 18, 2022): 292–97. http://dx.doi.org/10.32360/acmar.v55iespecial.78513.
Full textAbstract:
A Predicted Ocean is one of the UN Ocean Decade goals. Ocean observations and numerical simulations of the ocean circulation are at the heart of this outcome. Numerical models are used to understand the present and predict future ocean states, but also the human impact on it, among many other uses. However, its results are only a representation of reality, and we need to validate the numerical model outputs with observational data before using them. Considering its coast extension and the marine economic importance, Brazil does not collect enough physical ocean data and we have only a few real-time observation systems. Unfortunately, due to the COVID and the current national science budget crisis, the number of real-time observations has been further reduced. From a positive perspective, I must believe that this situation will change. We need to be prepared to convince the stakeholders of the importance of observing systems to our society and secure a budget in that regard. This is the way to better predict our oceans.
Keywords: ocean modeling, observation systems, Ocean Decade, numerical model validation.
3
Vella, Nicholas, Jamie Foley, James Sloat, Alexander Sandoval, Leonardo D’Attile, and Masoud Masoumi. "A Modular Wave Energy Converter for Observational and Navigational Buoys." Fluids 7, no. 2 (February 21, 2022): 88. http://dx.doi.org/10.3390/fluids7020088.
Full textAbstract:
More than 80% of the ocean is not fully mapped or even observed, even though it covers over 70% of our planet’s surface. One of the primary challenges for ocean observation and monitoring is the required power for exploration and monitoring systems, which often operate in remote areas of the ocean. This work addresses the design and development of an ocean wave energy converter that can be installed on observational buoys to provide enough power for sensors, cameras, data acquisition and recording, as well as data transfer units. The initial simulations of the prototype indicate that this system can produce up to 3.7–3.85 watts of power on average, with greater than 12 watts of maximum power in two selected sites in California and Hawaii. The proposed system is simple and low-cost. Further, multiple energy converters can be installed on one buoy to address higher power needs.
4
Karspeck, Alicia R. "An Ensemble Approach for the Estimation of Observational Error Illustrated for a Nominal 1° Global Ocean Model." Monthly Weather Review 144, no. 5 (May 2016): 1713–28. http://dx.doi.org/10.1175/mwr-d-14-00336.1.
Full textAbstract:
Least squares algorithms for data assimilation require estimates of both background error covariances and observational error covariances. The specification of these errors is an essential part of designing an assimilation system; the relative sizes of these uncertainties determine the extent to which the state variables are drawn toward the observational information. Observational error covariances are typically computed as the sum of measurement/instrumental errors and “representativeness error.” In a coarse-resolution ocean general circulation model the errors of representation are the dominant contribution to observational error covariance over large portions of the globe, and the size of these errors will vary by the type of observation and the geographic region. They may also vary from model to model. A straightforward approach for estimating model-dependent, spatially varying observational error variances that are suitable for least squares ocean data assimilating systems is presented here. The author proposes an ensemble-based estimator of the true observational error variance and outlines the assumptions necessary for the estimator to be unbiased. The author also presents the variance (or uncertainty) associated with the estimator under certain conditions. The analytic expressions for the expected value and variance of the estimator are validated with a simple autoregressive model and illustrated for the nominal 1° resolution POP2 global ocean general circulation model.
5
Tissier, Ann-Sophie, Jean-Michel Brankart, Charles-Emmanuel Testut, Giovanni Ruggiero, Emmanuel Cosme, and Pierre Brasseur. "A multiscale ocean data assimilation approach combining spatial and spectral localisation." Ocean Science 15, no. 2 (April 26, 2019): 443–57. http://dx.doi.org/10.5194/os-15-443-2019.
Full textAbstract:
Abstract. Ocean data assimilation systems encompass a wide range of scales that are difficult to control simultaneously using partial observation networks. All scales are not observable by all observation systems, which is not easily taken into account in current ocean operational systems. The main reason for this difficulty is that the error covariance matrices are usually assumed to be local (e.g. using a localisation algorithm in ensemble data assimilation systems), so that the large-scale patterns are removed from the error statistics. To better exploit the observational information available for all scales in the assimilation systems of the Copernicus Marine Environment Monitoring Service, we investigate a new method to introduce scale separation in the assimilation scheme. The method is based on a spectral transformation of the assimilation problem and consists in carrying out the analysis with spectral localisation for the large scales and spatial localisation for the residual scales. The target is to improve the observational update of the large-scale components of the signal by an explicit observational constraint applied directly on the large scales and to restrict the use of spatial localisation to the small-scale components of the signal. To evaluate our method, twin experiments are carried out with synthetic altimetry observations (simulating the Jason tracks), assimilated in a 1/4∘ model configuration of the North Atlantic and the Nordic Seas. Results show that the transformation to the spectral domain and the spectral localisation provides consistent ensemble estimates of the state of the system (in the spectral domain or after backward transformation to the spatial domain). Combined with spatial localisation for the residual scales, the new scheme is able to provide a reliable ensemble update for all scales, with improved accuracy for the large scale; and the performance of the system can be checked explicitly and separately for all scales in the assimilation system.
6
Black, Emily. "The relationship between Indian Ocean sea–surface temperature and East African rainfall." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1826 (January 15, 2005): 43–47. http://dx.doi.org/10.1098/rsta.2004.1474.
Full textAbstract:
Knowledge of the processes that control East African rainfall is essential for the development of seasonal forecasting systems, which may mitigate the effects of flood and drought. This study uses observational data to unravel the relationship between the Indian Ocean Dipole (IOD), the El Niño Southern Oscillation (ENSO) and rainy autumns in East Africa. Analysis of sea–surface temperature data shows that strong East African rainfall is associated with warming in the Pacific and Western Indian Oceans and cooling in the Eastern Indian Ocean. The resemblance of this pattern to that which develops during IOD events implies a link between the IOD and strong East African rainfall. Further investigation suggests that the observed teleconnection between East African rainfall and ENSO is a manifestation of a link between ENSO and the IOD.
7
Chu, Peter C., G. R. Amezaga, Jr, Eric L. Gottshall, and David S. Cwalina. "Ocean Nowcast/Forecast Systems for Improvement of Naval Undersea Capabilities." Marine Technology Society Journal 41, no. 2 (June 1, 2007): 23–30. http://dx.doi.org/10.4031/002533207787442178.
Full textAbstract:
The U.S. Navy is a major investor in ocean model development. The pay-off of such an investment is the value-added ocean nowcast/forecast systems on naval operations and warfare effectiveness. The purpose of this paper is to investigate the value added of the Navy's nowcast/forecast system to naval antisubmarine warfare (ASW) and anti-surface warfare (ASUW). The nowcast/forecast versus observational fields were used by the Weapon Acoustic Preset Program (WAPP) to determine the suggested presets for Mk 48 variant torpedo. The metric used to compare the two sets of outputs is the relative difference in acoustic coverage area generated by WAPP. Output presets are created for five different scenarios, two ASUW scenarios and three ASW scenarios in the South China Sea. The same metrics used in the nowcast/forecast case were used to generate and compare the acoustic coverage. Analysis of the output reveals that the ocean forecast system outperformed the nowcast system in most scenarios.
8
Cowles, Tim, and Mike Prince. "Renewal of the Academic Research Fleet." Marine Technology Society Journal 38, no. 2 (June 1, 2004): 55–62. http://dx.doi.org/10.4031/002533204787522794.
Full textAbstract:
Ocean research depends upon access to the sea—whether for exploration, monitoring, or experimentation. Access to the sea by academic scientists occurs primarily through the use of research vessels in the U.S. Academic Research Fleet. As the scientific discipline of oceanography has grown over the past several decades, our fundamental need for dependable observations of the ocean has not diminished. Research vessels continue to serve as the critical platforms for those observations, even as oceanographers expand the types and extent of observational and experimental approaches to include systems as diverse as satellites, remotely-operated vehicles, and molecular probes. As we look at the next ten to twenty years of scientific research into ocean processes, we must consider the advanced observational and experimental capabilities that scientists will expect from the Academic Fleet. The clear definition of those capabilities and requirements then can guide the design and construction of the next vessels in the fleet.The imminent retirements (by 2015) of over half the existing UNOLS fleet poses a significant challenge for implementation of the several new initiatives in ocean science, including ocean observing systems, ocean drilling, and multi-disciplinary expeditionary programs. Some of these vessels could (and likely will) continue operations beyond their scheduled retirement dates, but with greater maintenance costs and diminishing capabilities to conduct modern ocean science.The Fleet Renewal Plan, developed by the Federal Oceanographic Facilities Committee in 2001, addresses this major challenge and provides a pathway for sustaining our national capabilities for ocean research through the construction of new Regional and Ocean Class vessels. The National Science Foundation has begun the design process for the first of the Regional Class vessels, but no funding mechanism has yet been identified for constructing the Ocean Class vessels defined by the Fleet Renewal Plan. We urge continued strong support for full implementation of the Fleet Renewal Plan.
9
RAO, P. SANJEEVA. "Arabian Sea monsoon experiment: An overview." MAUSAM 56, no. 1 (January 19, 2022): 1–6. http://dx.doi.org/10.54302/mausam.v56i1.849.
Full textAbstract:
The Arabian Sea Monsoon Experiment (ARMEX) is one of the land-ocean-atmosphere field experiments implemented in June-July 2002 and March-June 2003 under the Indian Climate Research Programme. The broad scientific objectives of the ARMEX are (i) to study the offshore trough embedded mesoscale vortices (Arabian Sea convection) associated with intense rainfall events on the west coast of India during monsoon period, and (ii) to study the evolution, maintenance and the collapse of the Arabian Sea warm pool and onset phase of the monsoon. Conventional weather monitoring systems, weather satellite observational systems, ships, met-ocean buoys, automatic weather stations, surface layer meteorological towers and aircraft were deployed with state-of-the-art instrumentation for this experiment. This paper attempts to provide an overview of the ARMEX scientific objectives, implementation strategy, resource mobilization, infrastructure deployed, observational data collation, archival and initial analysis by the participating scientists.
10
van de Velde, Sebastiaan J., Christopher T. Reinhard, Andy Ridgwell, and Filip J. R. Meysman. "Bistability in the redox chemistry of sediments and oceans." Proceedings of the National Academy of Sciences 117, no. 52 (December 14, 2020): 33043–50. http://dx.doi.org/10.1073/pnas.2008235117.
Full textAbstract:
For most of Earth’s history, the ocean’s interior was pervasively anoxic and showed occasional shifts in ocean redox chemistry between iron-buffered and sulfide-buffered states. These redox transitions are most often explained by large changes in external inputs, such as a strongly altered delivery of iron and sulfate to the ocean, or major shifts in marine productivity. Here, we propose that redox shifts can also arise from small perturbations that are amplified by nonlinear positive feedbacks within the internal iron and sulfur cycling of the ocean. Combining observational evidence with biogeochemical modeling, we show that both sedimentary and aquatic systems display intrinsic iron–sulfur bistability, which is tightly linked to the formation of reduced iron–sulfide minerals. The possibility of tipping points in the redox state of sediments and oceans, which allow large and nonreversible geochemical shifts to arise from relatively small changes in organic carbon input, has important implications for the interpretation of the geological rock record and the causes and consequences of major evolutionary transitions in the history of Earth’s biosphere.
11
Schofield, Oscar, Scott Glenn, Paul W. Bissett, Thomas K. Frazer, Debora Iglesias-Rodriguez, and Mark A. Moline. "Development of Regional Coastal Ocean Observatories and the Potential Benefits to Marine Sanctuaries." Marine Technology Society Journal 37, no. 1 (March 1, 2003): 54–67. http://dx.doi.org/10.4031/002533203787537456.
Full textAbstract:
A network of coastal observatories is being built around the United States. While the motivations for developing these systems do not originate from marine sanctuaries per se, the sanctuaries stand to gain an unprecedented opportunity to benefit from real-time data and nowcasting/forecasting models. The construction of the observatories is being fueled by the rapid development in three enabling observational technologies. These technologies include (1) data acquisition systems that track the international constellation of IR and ocean color satellites; (2) nested grids multi-static SeaSonde surface current radars; and (3) a growing fleet of autonomous underwater vehicles. These observational assets are coupled to nowcast/forecast data assimilative models. These systems will allow the mean behavior in marine ecosystems to be defined while also providing real-time data that will allow adaptive sampling. The ability to adaptively sample the environment will allow scientists to make shrewd decisions about when and where to sample. Given this, developing the new approaches to measure critical biological processes and the geographic boundaries of those processes should be a key focus for the marine biology community. This will alter how scientists approach scientific questions in coastal waters.
12
Hopkins, Frances E., Parvadha Suntharalingam, Marion Gehlen, Oliver Andrews, Stephen D. Archer, Laurent Bopp, Erik Buitenhuis, et al. "The impacts of ocean acidification on marine trace gases and the implications for atmospheric chemistry and climate." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, no. 2237 (May 2020): 20190769. http://dx.doi.org/10.1098/rspa.2019.0769.
Full textAbstract:
Surface ocean biogeochemistry and photochemistry regulate ocean–atmosphere fluxes of trace gases critical for Earth's atmospheric chemistry and climate. The oceanic processes governing these fluxes are often sensitive to the changes in ocean pH (or p CO 2 ) accompanying ocean acidification (OA), with potential for future climate feedbacks. Here, we review current understanding (from observational, experimental and model studies) on the impact of OA on marine sources of key climate-active trace gases, including dimethyl sulfide (DMS), nitrous oxide (N 2 O), ammonia and halocarbons. We focus on DMS, for which available information is considerably greater than for other trace gases. We highlight OA-sensitive regions such as polar oceans and upwelling systems, and discuss the combined effect of multiple climate stressors (ocean warming and deoxygenation) on trace gas fluxes. To unravel the biological mechanisms responsible for trace gas production, and to detect adaptation, we propose combining process rate measurements of trace gases with longer term experiments using both model organisms in the laboratory and natural planktonic communities in the field. Future ocean observations of trace gases should be routinely accompanied by measurements of two components of the carbonate system to improve our understanding of how in situ carbonate chemistry influences trace gas production. Together, this will lead to improvements in current process model capabilities and more reliable predictions of future global marine trace gas fluxes.
13
Black, Bryan A., Carin Andersson, Paul G. Butler, Michael L. Carroll, Kristine L. DeLong, David J. Reynolds, Bernd R. Schöne, et al. "The revolution of crossdating in marine palaeoecology and palaeoclimatology." Biology Letters 15, no. 1 (January 2019): 20180665. http://dx.doi.org/10.1098/rsbl.2018.0665.
Full textAbstract:
Over the past century, the dendrochronology technique of crossdating has been widely used to generate a global network of tree-ring chronologies that serves as a leading indicator of environmental variability and change. Only recently, however, has this same approach been applied to growth increments in calcified structures of bivalves, fish and corals in the world's oceans. As in trees, these crossdated marine chronologies are well replicated, annually resolved and absolutely dated, providing uninterrupted multi-decadal to millennial histories of ocean palaeoclimatic and palaeoecological processes. Moreover, they span an extensive geographical range, multiple trophic levels, habitats and functional types, and can be readily integrated with observational physical or biological records. Increment width is the most commonly measured parameter and reflects growth or productivity, though isotopic and elemental composition capture complementary aspects of environmental variability. As such, crossdated marine chronologies constitute powerful observational templates to establish climate–biology relationships, test hypotheses of ecosystem functioning, conduct multi-proxy reconstructions, provide constraints for numerical climate models, and evaluate the precise timing and nature of ocean–atmosphere interactions. These ‘present–past–future’ perspectives provide new insights into the mechanisms and feedbacks between the atmosphere and marine systems while providing indicators relevant to ecosystem-based approaches of fisheries management.
14
Perez, Renellys C., Molly O. Baringer, Shenfu Dong, Silvia L. Garzoli, Marlos Goes, Gustavo J. Goni, Rick Lumpkin, Christopher S. Meinen, Rym Msadek, and Ulises Rivero. "Measuring the Atlantic Meridional Overturning Circulation." Marine Technology Society Journal 49, no. 2 (March 1, 2015): 167–77. http://dx.doi.org/10.4031/mtsj.49.2.14.
Full textAbstract:
AbstractThe Atlantic meridional overturning circulation (AMOC) plays a crucial role in redistributing heat and salt throughout the global oceans. Achieving a more complete understanding of the behavior of the AMOC system requires a comprehensive observational network that spans the entire Atlantic basin. This article describes several different types of observational systems that are used by scientists of the National Oceanographic and Atmospheric Administration and their partners at other national and international institutions to study the complex nature of the AMOC. The article also highlights several emerging technologies that will aid AMOC studies in the future.
15
Rastrick, Samuel S. P., Helen Graham, Kumiko Azetsu-Scott, Piero Calosi, Melissa Chierici, Agneta Fransson, Haakon Hop, et al. "Using natural analogues to investigate the effects of climate change and ocean acidification on Northern ecosystems." ICES Journal of Marine Science 75, no. 7 (October 16, 2018): 2299–311. http://dx.doi.org/10.1093/icesjms/fsy128.
Full textAbstract:
Abstract Northern oceans are in a state of rapid transition. Still, our knowledge of the likely effects of climate change and ocean acidification on key species in the food web, functionally important habitats and the structure of Arctic and sub-Arctic ecosystems is limited and based mainly on short-term laboratory studies on single species. This review discusses how tropical and temperate natural analogues of carbonate chemistry drivers, such as CO2 vents, have been used to further our knowledge of the sensitivity of biological systems to predicted climate change, and thus assess the capacity of different species to show long-term acclimation and adaptation to elevated levels of pCO2. Natural analogues have also provided the means to scale-up from single-species responses to community and ecosystem level responses. However, to date the application of such approaches is limited in high latitude systems. A range of Arctic and sub-Arctic sites, including CO2 vents, methane cold seeps, estuaries, up-welling areas, and polar fronts, that encompass gradients of pH, carbonate saturation state, and alkalinity, are suggested for future high latitude, in-situ ocean acidification research. It is recommended that combinations of monitoring of the chemical oceanography, observational, and experimental (in situ and laboratory) studies of organisms around these natural analogues be used to attain better predictions of the impacts of ocean acidification and climate change on high latitude species and ecosystems.
16
deCharon, Annette, Leslie M. Smith, and Carla Companion. "Characterizing Complex Marine Systems and Technology Using Visualized Vocabularies." Marine Technology Society Journal 49, no. 4 (July 1, 2015): 53–63. http://dx.doi.org/10.4031/mtsj.49.4.2.
Full textAbstract:
AbstractThe next decade will usher in significant changes in ocean observational infrastructure and how students engage with marine sciences content. Faced with the challenge of helping undergraduate students make sense of very complicated marine systems, a computer sciences-based organizational structure (i.e., ontology) has been employed to characterize the Ocean Observatories Initiative (OOI). Five interlinked vocabularies that include terms, descriptions, and images define the overall system from high-level science themes to specialized data products. Given the importance of visual representations in learning, particularly for novices, an associated interactive tool called the “Vocabulary Navigator” has been developed. Created in tandem, the design of the vocabularies and their visualizer is based on principles related to the needs of the target audience such as placing information in a broader context and promoting self-directed discovery. Overall, this effort has resulted in not only innovative online resources for learning about the OOI but also, perhaps more importantly, valuable “lessons learned” and transferable software that could be used by other marine technology endeavors.
17
Spence, Lundie, Blake A. Schaeffer, Carrie Thomas, Terri Kirby Hathaway, and Margaret Olsen. "Coastal Ocean Observing Technology Transfer to Educators." Marine Technology Society Journal 39, no. 4 (December 1, 2005): 78–82. http://dx.doi.org/10.4031/002533205787465931.
Full textAbstract:
Coastal ocean observing systems provide an opportunity to connect scientific concepts, technology and careers to education. These systems also provide outreach opportunities for researchers to connect beyond their peers to the public. Use of real/near real-time coastal ocean observational data has local relevance and can generate excitement for teachers and students about the changes and patterns in the ocean environment. New collaborations, strategies and models must be forged between scientists and educators to meet challenges and provide benefits. Challenges include the identification of connections between coastal ocean observing science and precollege science standards and curricula, the design of effective professional development workshops to transfer technology to teachers, the development of Web-based observation data that is accessible to teachers and their students, and the construction and testing of model inquiry lessons, which include use of real/near real-time observations data and GIS maps. Benefits include outreach opportunities for researchers, inquiry-driven applications for precollege students and the introduction of coastal ocean observing to students with the outcome of a highly trained and diverse work force in ocean sciences for the future. Effective strategies for transfer require new opportunities for engagement between scientists and educators, sharing of credit, evaluations, and solid technical reviews of all products to ensure scientific and educational accuracy.
18
SIKKA, D. R. "From the International Indian Ocean Expedition (IIOE) to the Arabian Sea Monsoon Experiment (ARMEX) – four decades of major advances in monsoon meteorology." MAUSAM 56, no. 1 (January 19, 2022): 19–36. http://dx.doi.org/10.54302/mausam.v56i1.855.
Full textAbstract:
Vast amount of researches on describing understanding, modelling and prediction of monsoon have taken place in the last 50 years or so as new observational and computational technologies have been introduced. Several field observational programs using state of the art sea-land and space-based observational systems have been undertaken nationally and internationally in the last 4 decades beginning with the IIOE (1963-1965) and culminating in the ARMEX (2002, 2003) which have given new challenges to monsoon-related research. The paper provides salient features of the research on the Indian monsoon accomplished during the four decades (1963-2003) using observational and modelling studies and the discusses new challenges which lie ahead for its further improved understanding and prediction.
19
Dushaw, Brian D., and Hanne Sagen. "A Comparative Study of Moored/Point and Acoustic Tomography/Integral Observations of Sound Speed in Fram Strait Using Objective Mapping Techniques." Journal of Atmospheric and Oceanic Technology 33, no. 10 (October 2016): 2079–93. http://dx.doi.org/10.1175/jtech-d-15-0251.1.
Full textAbstract:
AbstractEstimation of the exchange of seawater of various properties between the Arctic and North Atlantic Oceans presents a challenging observational problem. The strong current systems within Fram Strait induce recirculations and a turbulent ocean environment dominated by mesoscale variations of 4–10-km scale. By employing a simple parameterized model for mesoscale variability within Fram Strait, the authors examine the ability of a line array of closely spaced moorings and an acoustic tomography line to measure the average sound speed, a proxy variable for ocean temperature or heat content. Objective maps are employed to quantify the uncertainties resulting from the different measurement approaches. While measurements by a mooring line and tomography result in similar uncertainties in estimations of range- and depth-averaged sound speed, the combination of the two approaches gives uncertainties 3 times smaller. The two measurements are sufficiently different as to be complementary; one measurement provides resolution for the aspects of the temperature section that the other misses. The parameterized model and its assumptions as to the magnitudes and scales of variability were tested by application to a hydrographic section across Fram Strait measured in 2011. This study supports the deployment of the 2013–16 Arctic Ocean under Melting Ice (UNDER-ICE) network of tomographic transceivers spanning the ongoing moored array line across Fram Strait. Optimal estimation for this ocean environment may require combining disparate data types as constraints on a numerical ocean model using data assimilation.
20
Uboldi, F., and A. Trevisan. "Detecting unstable structures and controlling error growth by assimilation of standard and adaptive observations in a primitive equation ocean model." Nonlinear Processes in Geophysics 13, no. 1 (March 24, 2006): 67–81. http://dx.doi.org/10.5194/npg-13-67-2006.
Full textAbstract:
Abstract. Oceanic and atmospheric prediction is based on cyclic analysis-forecast systems that assimilate new observations as they become available. In such observationally forced systems, errors amplify depending on their components along the unstable directions; these can be estimated by Breeding on the Data Assimilation System (BDAS). Assimilation in the Unstable Subspace (AUS) uses the available observations to estimate the amplitude of the unstable structures (computed by BDAS), present in the forecast error field, in order to eliminate them and to control the error growth. For this purpose, it is crucial that the observational network can detect the unstable structures that are active in the system. These concepts are demonstrated here by twin experiments with a large state dimension, primitive equation ocean model and an observational network having a fixed and an adaptive component. The latter consists of observations taken each time at different locations, chosen to target the estimated instabilities, whose positions and features depend on the dynamical characteristics of the flow. The adaptive placement and the dynamically consistent assimilation of observations (both relying upon the estimate of the unstable directions of the data-forced system), allow to obtain a remarkable reduction of errors with respect to a non-adaptive setting. The space distribution of the positions chosen for the observations allows to characterize the evolution of instabilities, from deep layers in western boundary current regions, to near-surface layers in the eastward jet area.
21
Brown, J., C. A. Clayson, L. Kantha, and T. Rojsiraphisal. "North Indian Ocean variability during the Indian Ocean dipole." Ocean Science Discussions 5, no. 2 (June 9, 2008): 213–53. http://dx.doi.org/10.5194/osd-5-213-2008.
Full textAbstract:
Abstract. The circulation in the North Indian Ocean (NIO henceforth) is highly seasonally variable. Periodically reversing monsoon winds (southwesterly during summer and northeasterly during winter) give rise to seasonally reversing current systems off the coast of Somalia and India. In addition to this annual monsoon cycle, the NIO circulation varies semiannually because of equatorial currents reversing four times each year. These descriptions are typical, but how does the NIO circulation behave during anomalous years, during an Indian Ocean dipole (IOD) for instance? Unfortunately, in situ observational data are rather sparse and reliance has to be placed on numerical models to understand this variability. In this paper, we estimate the surface current variability from a 12-year hindcast of the NIO for 1993–2004 using a 1/2° resolution circulation model that assimilates both altimetric sea surface height anomalies and sea surface temperature. Presented in this paper is an examination of surface currents in the NIO basin during the IOD. During the non-IOD period of 2000–2004, the typical equatorial circulation of the NIO reverses four times each year and transports water across the basin preventing a large sea surface temperature difference between the western and eastern NIO. Conversely, IOD years are noted for strong easterly and westerly wind outbursts along the equator. The impact of these outbursts on the NIO circulation is to reverse the direction of the currents – when compared to non-IOD years – during the summer for negative IOD events (1996 and 1998) and during the fall for positive IOD events (1994 and 1997). This reversal of current direction leads to large temperature differences between the western and eastern NIO.
22
Zhai, Xiaoming, and Carl Wunsch. "On the Variability of Wind Power Input to the Oceans with a Focus on the Subpolar North Atlantic." Journal of Climate 26, no. 11 (May 31, 2013): 3892–903. http://dx.doi.org/10.1175/jcli-d-12-00472.1.
Full textAbstract:
Abstract Variations in power input to the ocean using a recent global “reanalysis” extending back to 1871 show a strong trend in the net power input since then, a trend dominated by the Southern Ocean region. This trend is interpreted as a spurious result of the changing observational system. Focusing therefore on the North Atlantic Ocean, where the database is somewhat more secure, it is found that the input power in the subpolar North Atlantic varies significantly in time, showing a strong relationship to the North Atlantic Oscillation (NAO). During positive NAO index years, power input is greater owing to enhanced synoptic activity. Furthermore, cumulative power input to the subpolar North Atlantic is found to correlate significantly with both the eddy kinetic energy there and the Atlantic multidecadal oscillation (AMO), although the physical mechanism at work remains unclear. The assumption that the changing ocean can be neglected relative to the changing atmosphere in calculating the power input is found to be a usefully accurate approximation over the two decades for which changing ocean state estimates are available. Strong dependence on synoptic weather systems of monthly-mean stress distributions implies that past and future climate simulations must account properly for changes in weather systems, not just the large-scale variations.
23
Sepúlveda, Héctor H., Patrick Marchesiello, and Zhijin Li. "Oceanic data assimilation study in northern Chile: use of a 3DVAR method." Latin American Journal of Aquatic Research 41, no. 3 (March 8, 2017): 570–75. http://dx.doi.org/10.3856/vol41-issue3-fulltext-18.
Full textAbstract:
We report the use of a 3-dimensional variational (3DVAR) data assimilation method as part of a numerical model off northern Chile. The numerical model is part of an ocean forecasting project that aims to understand the impact of environmental variability on the distribution of biological species in the area. We assimilated data from a simulated ocean observing system to recover a known state, obtaining a significantly smaller error when compared to a numerical run with no assimilation. Our results validate the computational implementation of the code, and allow us to evaluate the impact of the choice of data in the assimilation process: the assimilation of sea surface height being particularly important. We note that the assimilation of surface data propagates properly to greater depths and reduces the error with reference to the known state. This was possible by using covariance error matrices calculated previously for the California coastal area. The implementation of the data assimilation module is relatively simple and permits its use in operational forecasting systems, and for the design and evaluation of future ocean observational systems.
24
Bourassa, Mark A., and Kelly McBeth Ford. "Uncertainty in Scatterometer-Derived Vorticity." Journal of Atmospheric and Oceanic Technology 27, no. 3 (March 1, 2010): 594–603. http://dx.doi.org/10.1175/2009jtecho689.1.
Full textAbstract:
Abstract A more versatile and robust technique is developed for determining area-averaged surface vorticity based on vector winds from swaths of remotely sensed wind vectors. This technique could also be applied to determine the curl of stress, and it could be applied to any gridded dataset of winds or stresses. The technique is discussed in detail and compared to two previous studies that focused on early development of tropical systems. Error characteristics of the technique are examined in detail. Specifically, three independent sources of error are explored: random observational error, truncation error, and representation error. Observational errors are due to random errors in the wind observations and determined as a worst-case estimate as a function of averaging spatial scale. The observational uncertainty in the Quick Scatterometer (QuikSCAT)-derived vorticity averaged for a roughly circular shape with a 100-km diameter, expressed as one standard deviation, is approximately 0.5 × 10−5 s−1 for the methodology described herein. Truncation error is associated with the assumption of linear changes between wind vectors. Uncertainty related to truncation has more spatial organization in QuikSCAT data than observational uncertainty. On 25- and 50-km scales, the truncation errors are very large. The third type of error, representation error, is due to the size of the area being averaged compared to values with 25-km length scales. This type of error is analogous to oversmoothing. Tropical and subtropical low pressure systems from three months of QuikSCAT observations are used to examine truncation and representation errors. Representation error results in a bias of approximately −1.5 × 10−5 s−1 for area-averaged vorticity calculated on a 100-km scale compared to vorticity calculated on a 25-km scale. The discussion of these errors will benefit future projects of this nature as well as future satellite missions.
25
Garreaud, R. D., J. A. Rutllant, R. C. Muñoz, D. A. Rahn, M. Ramos, and D. Figueroa. "VOCALS-CUpEx: the Chilean Upwelling Experiment." Atmospheric Chemistry and Physics Discussions 10, no. 11 (November 5, 2010): 26437–72. http://dx.doi.org/10.5194/acpd-10-26437-2010.
Full textAbstract:
Abstract. The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) was a major field experiment conducted in spring of 2008 off southern Peru and northern Chile, aimed at better understanding the coupled climate systems of the southeast Pacific. Because of logistical constrains, the coastal area around 30° S was not sampled during VOCALS-REx. This area not only marks the poleward edge of the subtropical stratocumulus cloud regime (thus acting as a source of transient disturbances) but is also one of the most active upwelling centers and source of surface ocean kinetic energy along the Chilean coast. To fill such an observational gap, a small, brief, but highly focused field experiment was conducted in late spring 2009 in the near-shore region around 30° S. The Chilean Upwelling Experiment (CUpEx) was endorsed by VOCALS as a regional component. CUpEx included long-term monitoring, an intensive two-week field campaign and off-shore research flights. Our goal was to obtain an atmospheric/oceanic dataset with enough temporal and spatial coverage to be able to document (a) the mean diurnal cycles of the lower-troposphere and upper-ocean in a region of complex topography and coastline geometry, and (b) the ocean-atmosphere response to the rapid changes in coastal winds from strong, upwelling-favorable southerly winds to relaxed southerlies or even downwelling-favorable northerlies. In this paper we describe the measurement platforms and sampling strategy, and provide an observational overview, highlighting some key mean and transient features.
26
Dupont, F., S. Higginson, R. Bourdallé-Badie, Y. Lu, F. Roy, G. C. Smith, J. F. Lemieux, G. Garric, and F. Davidson. "A high-resolution ocean and sea-ice modelling system for the Arctic and North Atlantic oceans." Geoscientific Model Development 8, no. 5 (May 28, 2015): 1577–94. http://dx.doi.org/10.5194/gmd-8-1577-2015.
Full textAbstract:
Abstract. As part of the CONCEPTS (Canadian Operational Network of Coupled Environmental PredicTion Systems) initiative, a high-resolution (1/12°) ice–ocean regional model is developed covering the North Atlantic and the Arctic oceans. The long-term objective is to provide Canada with short-term ice–ocean predictions and hazard warnings in ice-infested regions. To evaluate the modelling component (as opposed to the analysis – or data-assimilation – component, which is not covered in this contribution), a series of hindcasts for the period 2003–2009 is carried out, forced at the surface by the Canadian GDPS reforecasts (Smith et al., 2014). These hindcasts test how the model represents upper ocean characteristics and ice cover. Each hindcast implements a new aspect of the modelling or the ice–ocean coupling. Notably, the coupling to the multi-category ice model CICE is tested. The hindcast solutions are then assessed using a verification package under development, including in situ and satellite ice and ocean observations. The conclusions are as follows: (1) the model reproduces reasonably well the time mean, variance and skewness of sea surface height; (2) the model biases in temperature and salinity show that while the mean properties follow expectations, the Pacific Water signature in the Beaufort Sea is weaker than observed; (3) the modelled freshwater content of the Arctic agrees well with observational estimates; (4) the distribution and volume of the sea ice are shown to be improved in the latest hindcast due to modifications to the drag coefficients and to some degree to the ice thickness distribution available in CICE; (5) nonetheless, the model still overestimates the ice drift and ice thickness in the Beaufort Gyre.
27
Dupont, F., S. Higginson, R. Bourdallé-Badie, Y. Lu, F. Roy, G. C. Smith, J. F. Lemieux, G. Garric, and F. Davidson. "A high-resolution ocean and sea-ice modelling system for the Arctic and North Atlantic Oceans." Geoscientific Model Development Discussions 8, no. 1 (January 5, 2015): 1–52. http://dx.doi.org/10.5194/gmdd-8-1-2015.
Full textAbstract:
Abstract. As part of the CONCEPTS (Canadian Operational Network of Coupled Environmental PredicTion Systems) initiative, The Government of Canada is developing a high resolution (1/12°) ice–ocean regional model covering the North Atlantic and the Arctic oceans. The objective is to provide Canada with short-term ice–ocean predictions and hazard warnings in ice infested regions. To evaluate the modelling component (as opposed to the analysis – or data-assimilation – component), a series of hindcasts for the period 2003–2009 is carried out, forced at the surface by the Canadian Global Re-Forecasts. These hindcasts test how the model represent upper ocean characteristics and ice cover. Each hindcast implements a new aspect of the modelling or the ice–ocean coupling. Notably, the coupling to the multi-category ice model CICE is tested. The hindcast solutions are then assessed using a validation package under development, including in-situ and satellite ice and ocean observations. The conclusions are: (1) the model reproduces reasonably well the time mean, variance and skewness of sea surface height. (2) The model biases in temperature and salinity show that while the mean properties follow expectations, the Pacific Water signature in the Beaufort Sea is weaker than observed. (3) However, the modelled freshwater content of the Arctic agrees well with observational estimates. (4) The distribution and volume of the sea ice is shown to be improved in the latest hindcast thanks to modifications to the drag coefficients and to some degree as well to the ice thickness distribution available in CICE. (5) On the other hand, the model overestimates the ice drift and ice thickness in the Beaufort Gyre.
28
Siqueira, L., B. P. Kirtman, and L. C. Laurindo. "Forecasting Remote Atmospheric Responses to Decadal Kuroshio Stability Transitions." Journal of Climate 34, no. 1 (January 2021): 379–95. http://dx.doi.org/10.1175/jcli-d-20-0139.1.
Full textAbstract:
AbstractBased on observational estimates and global ocean eddy-resolving coupled retrospective initialized predictions, we show that Kuroshio Extension variability affects rainfall variability along the west coast of North America. We show that the teleconnection between the current undulations and downstream rainfall can lead to improved subseasonal to seasonal predictions of precipitation over California, and we demonstrate that capturing these teleconnections requires coupled systems with sufficient ocean resolution (i.e., eddy-resolving), especially over time scales longer than one season. The improved forecast skill is diagnosed in terms of 35 years of retrospective initialized ensemble forecasts with an ocean eddy-resolving and an ocean eddy-parameterized coupled model. Not only does the ocean eddy-resolving model show sensitivity to Kuroshio Extension variability in terms of western North America precipitation, but the ocean eddy-resolving forecasts also show improved forecast skill compared to the ocean eddy-parameterized model. The ocean eddy-parameterized coupled model shows no sensitivity to Kuroshio Extension variability. We also find near-decadal variability associated with a progression of a lower-tropospheric height dipole around the North Pacific and how these height anomalies lead to wind-driven Rossby waves that affect the eddy activity in the Kuroshio Extension with a time lag on the order of four years. This decadal-scale variability (~10 years) opens the possibility of multiyear predictability of western North American rainfall.
29
Garreaud, R. D., J. A. Rutllant, R. C. Muñoz, D. A. Rahn, M. Ramos, and D. Figueroa. "VOCALS-CUpEx: the Chilean Upwelling Experiment." Atmospheric Chemistry and Physics 11, no. 5 (March 4, 2011): 2015–29. http://dx.doi.org/10.5194/acp-11-2015-2011.
Full textAbstract:
Abstract. The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) was a major field experiment conducted in spring of 2008 off southern Peru and northern Chile, aimed at better understanding the coupled climate systems of the southeast Pacific. Because of logistical constrains, the coastal area around 30° S was not sampled during VOCALS-REx. This area not only marks the poleward edge of the subtropical stratocumulus cloud regime (thus acting as a source of transient disturbances) but is also one of the most active upwelling centers and source of surface ocean kinetic energy along the Chilean coast. To fill such an observational gap, a small, brief, but highly focused field experiment was conducted in late spring 2009 in the near-shore region around 30° S. The Chilean Upwelling Experiment (CUpEx) was endorsed by VOCALS as a regional component. CUpEx included long-term monitoring, an intensive two-week field campaign and off-shore research flights. Our goal was to obtain an atmospheric/oceanic dataset with enough temporal and spatial coverage to be able to document (a) the mean diurnal cycles of the lower-troposphere and upper-ocean in a region of complex topography and coastline geometry, and (b) the ocean-atmosphere response to the rapid changes in coastal winds from strong, upwelling-favorable equatorward flow (southerly winds) to downwelling-favorable poleward flow (northerly winds). In this paper we describe the measurement platforms and sampling strategy, and provide an observational overview, highlighting some key mean-state and transient features.
30
Jiang, Haoyu, and Lin Mu. "Wave Climate from Spectra and Its Connections with Local and Remote Wind Climate." Journal of Physical Oceanography 49, no. 2 (February 2019): 543–59. http://dx.doi.org/10.1175/jpo-d-18-0149.1.
Full textAbstract:
AbstractWind-generated waves can propagate over large distances. Therefore, wave spectra from a fixed point can record information about air–sea interactions in distant areas. In this study, the spectral wave climate for a point in the tropical eastern Pacific Ocean is computed. Several well-defined wave climate systems are observed in the mean wave spectrum. Significant seasonal cycling, long-term trends, and correlations with the Southern Oscillation, the Arctic Oscillation, and the Antarctic Oscillation are observed in the local wave spectra, showing abundant climatic information. Projections of wind vectors on the directions pointing to the target location are used to connect the spectral wave climate and basin-scale wind climate, because significant correlations are observed between the wave spectra and the wind projections of both local and remote wind systems. The origins of all the identified wave climate systems, including the westerlies and the trade winds in both hemispheres, are clearly shown in wind projection maps. Some of these origins are thousands of kilometers away from the target point, demonstrating the validity of this connection. Comparisons are made between wave spectra and the corresponding local and remote wind fields with respect to seasonal and interannual variability and long-term trends. The results show that each frequency and direction of ocean wave spectra at a certain location can be approximately linked to the wind field for a geographical area, implying that it is feasible to reconstruct spectral wave climates from observational wind field data and monitor wind climates from observational wave spectra geographically far away.
31
Garcia, Rigoberto F., and Christopher S. Meinen. "Accuracy of Florida Current Volume Transport Measurements at 27°N Using Multiple Observational Techniques." Journal of Atmospheric and Oceanic Technology 31, no. 5 (May 2014): 1169–80. http://dx.doi.org/10.1175/jtech-d-13-00148.1.
Full textAbstract:
AbstractFor more than 30 years, the volume transport of the Florida Current at 27°N has been regularly estimated both via voltage measurements on a submarine cable and using ship-based measurements of horizontal velocity at nine historical stations across the Florida Straits. A comparison of three different observational systems is presented, including a detailed evaluation of observational accuracy and precision. The three systems examined are dropsonde (free-falling float), lowered acoustic Doppler current profiler (LADCP), and submarine cable. The accuracy of the Florida Current transport calculation from dropsonde sections, which can be determined from first principles with existing data, is shown to be 0.8 Sv (1 Sv ≡ 106 m3 s−1). Side-by-side comparisons between dropsonde and LADCP measurements are used to show that the LADCP-based transport estimates are accurate to within 1.3 Sv. Dropsonde data are often used to set the absolute mean cable transport estimate, so some care is required in establishing the absolute accuracy of the cable measurements. Used together, the dropsonde and LADCP sections can be used to evaluate the absolute accuracy and precision of the cable measurements. These comparisons suggest the daily cable observations are accurate to within 1.7 Sv, and analysis of the decorrelation time scales for the errors suggests that annual transport averages from the cable are accurate to within 0.3 Sv. The implications of these accuracy estimates for long-term observation of the Florida Current are discussed in the context of maintaining this key climate record.
32
Ossó, Albert, Rowan Sutton, Len Shaffrey, and Buwen Dong. "Observational evidence of European summer weather patterns predictable from spring." Proceedings of the National Academy of Sciences 115, no. 1 (December 18, 2017): 59–63. http://dx.doi.org/10.1073/pnas.1713146114.
Full textAbstract:
Forecasts of summer weather patterns months in advance would be of great value for a wide range of applications. However, seasonal dynamical model forecasts for European summers have very little skill, particularly for rainfall. It has not been clear whether this low skill reflects inherent unpredictability of summer weather or, alternatively, is a consequence of weaknesses in current forecast systems. Here we analyze atmosphere and ocean observations and identify evidence that a specific pattern of summertime atmospheric circulation––the summer East Atlantic (SEA) pattern––is predictable from the previous spring. An index of North Atlantic sea-surface temperatures in March–April can predict the SEA pattern in July–August with a cross-validated correlation skill above 0.6. Our analyses show that the sea-surface temperatures influence atmospheric circulation and the position of the jet stream over the North Atlantic. The SEA pattern has a particularly strong influence on rainfall in the British Isles, which we find can also be predicted months ahead with a significant skill of 0.56. Our results have immediate application to empirical forecasts of summer rainfall for the United Kingdom, Ireland, and northern France and also suggest that current dynamical model forecast systems have large potential for improvement.
33
Tilinina, Natalia, Dmitry Ivonin, Alexander Gavrikov, Vitali Sharmar, Sergey Gulev, Alexander Suslov, Vladimir Fadeev, et al. "Wind waves in the North Atlantic from ship navigational radar: SeaVision development and its validation with the Spotter wave buoy and WaveWatch III." Earth System Science Data 14, no. 8 (August 11, 2022): 3615–33. http://dx.doi.org/10.5194/essd-14-3615-2022.
Full textAbstract:
Abstract. Wind waves play an important role in the climate system, modulating the energy exchange between the ocean and the atmosphere and effecting ocean mixing. However, existing ship-based observational networks of wind waves are still sparse, limiting therefore the possibilities of validating satellite missions and model simulations. In this paper we present data collected on three research cruises in the North Atlantic and Arctic in 2020 and 2021 and the SeaVision system for measuring wind wave characteristics over the open ocean with a standard marine navigation X-band radar. Simultaneously with the SeaVision wind wave characteristic measurements, we also collected data from the Spotter wave buoy at the same locations, and we ran the WaveWatch III model in a very high-resolution configuration over the observational domain. SeaVision measurements were validated against co-located Spotter wave buoy data and intercompared with the output of WaveWatch III simulations. Observations of the wind waves with the navigation X-band radar were found to be in good agreement with buoy data and model simulations with the best match for the wave propagation directions. Supporting datasets consist of significant wave heights, wave directions, wave periods and wave energy frequency spectra derived from both SeaVision and the Spotter buoy. All supporting data are available through the PANGAEA repository – https://doi.org/10.1594/PANGAEA.939620 (Gavrikov et al., 2021). The dataset can be further used for validation of satellite missions and regional wave model experiments. Our study shows the potential of ship navigation X-band radars (when assembled with SeaVision or similar systems) for the development of a new near-global observational network providing a much larger number of wind wave observations compared to e.g. Voluntary Observing Ship (VOS) data and research vessel campaigns.
34
Haus, Brian K., David G. Ortiz-Suslow, James D. Doyle, David D. Flagg, Hans C. Graber, Jamie MacMahan, Lian Shen, Qing Wang, Neil J. Willams, and Caglar Yardim. "CLASI: Coordinating Innovative Observations and Modeling to Improve Coastal Environmental Prediction Systems." Bulletin of the American Meteorological Society 103, no. 3 (March 2022): E889—E898. http://dx.doi.org/10.1175/bams-d-20-0304.1.
Full textAbstract:
Abstract The Coastal Land–Air–Sea Interaction (CLASI) project aims to develop new “coast-aware” atmospheric boundary and surface layer parameterizations that represent the complex land–sea transition region through innovative observational and numerical modeling studies. The CLASI field effort involves an extensive array of more than 40 land- and ocean-based moorings and towers deployed within varying coastal domains, including sandy, rocky, urban, and mountainous shorelines. Eight Air–Sea Interaction Spar (ASIS) buoys are positioned within the coastal and nearshore zone, the largest and most concentrated deployment of this unique, established measurement platform. Additionally, an array of novel nearshore buoys and a network of land-based surface flux towers are complemented by spatial sampling from aircraft, shore-based radars, drones, and satellites. CLASI also incorporates unique electromagnetic wave (EM) propagation measurements using a coherent array, drone receiver, and a marine radar to understand evaporation duct variability in the coastal zone. The goal of CLASI is to provide a rich dataset for validation of coupled, data assimilating large-eddy simulations (LES) and the Navy’s Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS). CLASI observes four distinct coastal regimes within Monterey Bay, California (MB). By coordinating observations with COAMPS and LES simulations, the CLASI efforts will result in enhanced understanding of coastal physical processes and their representation in numerical weather prediction (NWP) models tailored to the coastal transition region. CLASI will also render a rich dataset for model evaluation and testing in support of future improvements to operational forecast models.
35
Dubrov, M. N., V. A. Volkov, and S. P. Golovachev. "Earthquake and hurricane coupling is ascertained by ground-based laser interferometer and satellite observing techniques." Natural Hazards and Earth System Sciences Discussions 2, no. 1 (January 30, 2014): 935–61. http://dx.doi.org/10.5194/nhessd-2-935-2014.
Full textAbstract:
Abstract. The most destructive disasters such as the strongest earthquakes and the most powerful tropical cyclones can be treated as tightly coupled geophysical phenomena in their origin. Results of comparison of geophysical field variations and seismic activity of the Earth have evidently shown the correlation between lithosphere–atmosphere interactive disturbances, tropical cyclonic activity in the World Ocean, and seismic processes in the solid Earth. The ground-based laser interferometer techniques being supplemented by satellite observational systems can be considered as promising methods for common earthquake and hurricane monitoring and prediction.
36
Kwon, Young-Oh, Michael A. Alexander, Nicholas A. Bond, Claude Frankignoul, Hisashi Nakamura, Bo Qiu, and Lu Anne Thompson. "Role of the Gulf Stream and Kuroshio–Oyashio Systems in Large-Scale Atmosphere–Ocean Interaction: A Review." Journal of Climate 23, no. 12 (June 15, 2010): 3249–81. http://dx.doi.org/10.1175/2010jcli3343.1.
Full textAbstract:
Abstract Ocean–atmosphere interaction over the Northern Hemisphere western boundary current (WBC) regions (i.e., the Gulf Stream, Kuroshio, Oyashio, and their extensions) is reviewed with an emphasis on their role in basin-scale climate variability. SST anomalies exhibit considerable variance on interannual to decadal time scales in these regions. Low-frequency SST variability is primarily driven by basin-scale wind stress curl variability via the oceanic Rossby wave adjustment of the gyre-scale circulation that modulates the latitude and strength of the WBC-related oceanic fronts. Rectification of the variability by mesoscale eddies, reemergence of the anomalies from the preceding winter, and tropical remote forcing also play important roles in driving and maintaining the low-frequency variability in these regions. In the Gulf Stream region, interaction with the deep western boundary current also likely influences the low-frequency variability. Surface heat fluxes damp the low-frequency SST anomalies over the WBC regions; thus, heat fluxes originate with heat anomalies in the ocean and have the potential to drive the overlying atmospheric circulation. While recent observational studies demonstrate a local atmospheric boundary layer response to WBC changes, the latter’s influence on the large-scale atmospheric circulation is still unclear. Nevertheless, heat and moisture fluxes from the WBCs into the atmosphere influence the mean state of the atmospheric circulation, including anchoring the latitude of the storm tracks to the WBCs. Furthermore, many climate models suggest that the large-scale atmospheric response to SST anomalies driven by ocean dynamics in WBC regions can be important in generating decadal climate variability. As a step toward bridging climate model results and observations, the degree of realism of the WBC in current climate model simulations is assessed. Finally, outstanding issues concerning ocean–atmosphere interaction in WBC regions and its impact on climate variability are discussed.
37
Hutchinson, D. J., and V. Falmagne. "Observational design of underground cable bolt support systems utilizing instrumentation." Bulletin of Engineering Geology and the Environment 58, no. 3 (April 4, 2000): 227–41. http://dx.doi.org/10.1007/s100640050078.
Full text
38
Ding, Liudan, Tim Li, Baoqiang Xiang, and Melinda Peng. "On the Westward Turning of Hurricane Sandy (2012): Effect of Atmospheric Intraseasonal Oscillations." Journal of Climate 32, no. 20 (September 13, 2019): 6859–73. http://dx.doi.org/10.1175/jcli-d-18-0663.1.
Full textAbstract:
Abstract Hurricane Sandy (2012) experienced an unusual westward turning and made landfall in New Jersey after its northward movement over the Atlantic Ocean. The landfall caused severe casualties and great economic losses. The westward turning took place in the midlatitude Atlantic where the climatological mean wind is eastward. The cause of this unusual westward track is investigated through both observational analysis and model simulations. The observational analysis indicates that the hurricane steering flow was primarily controlled by atmospheric intraseasonal oscillation (ISO), which was characterized by a pair of anticyclonic and cyclonic circulation systems. The anticyclone to the north was part of a global wave train forced by convection over the tropical Indian Ocean through Rossby wave energy dispersion, and the cyclone to the south originated from the tropical Atlantic through northward propagation. Hindcast experiments using a global coupled model show that the model is able to predict the observed circulation pattern as well as the westward steering flow 6 days prior to Sandy’s landfall. Sensitivity experiments with different initial dates confirm the important role of the ISO in establishing the westward steering flow in the midlatitude Atlantic. Thus the successful numerical model experiments suggest a potential for extended-range dynamical tropical cyclone track predictions.
39
Stanev, Emil V., Johannes Schulz-Stellenfleth, Joanna Staneva, Sebastian Grayek, Sebastian Grashorn, Arno Behrens, Wolfgang Koch, and Johannes Pein. "Ocean forecasting for the German Bight: from regional to coastal scales." Ocean Science 12, no. 5 (October 7, 2016): 1105–36. http://dx.doi.org/10.5194/os-12-1105-2016.
Full textAbstract:
Abstract. This paper describes recent developments based on advances in coastal ocean forecasting in the fields of numerical modeling, data assimilation, and observational array design, exemplified by the Coastal Observing System for the North and Arctic Seas (COSYNA). The region of interest is the North and Baltic seas, and most of the coastal examples are for the German Bight. Several pre-operational applications are presented to demonstrate the outcome of using the best available science in coastal ocean predictions. The applications address the nonlinear behavior of the coastal ocean, which for the studied region is manifested by the tidal distortion and generation of shallow-water tides. Led by the motivation to maximize the benefits of the observations, this study focuses on the integration of observations and modeling using advanced statistical methods. Coastal and regional ocean forecasting systems do not operate in isolation but are linked, either weakly by using forcing data or interactively using two-way nesting or unstructured-grid models. Therefore, the problems of downscaling and upscaling are addressed, along with a discussion of the potential influence of the information from coastal observatories or coastal forecasting systems on the regional models. One example of coupling coarse-resolution regional models with a fine-resolution model interface in the area of straits connecting the North and Baltic seas using a two-way nesting method is presented. Illustrations from the assimilation of remote sensing, in situ and high-frequency (HF) radar data, the prediction of wind waves and storm surges, and possible applications to search and rescue operations are also presented. Concepts for seamless approaches to link coastal and regional forecasting systems are exemplified by the application of an unstructured-grid model for the Ems Estuary.
40
Williams, Christopher N., Stephen L. Cornford, Thomas M. Jordan, Julian A. Dowdeswell, Martin J. Siegert, Christopher D. Clark, Darrel A. Swift, Andrew Sole, Ian Fenty, and Jonathan L. Bamber. "Generating synthetic fjord bathymetry for coastal Greenland." Cryosphere 11, no. 1 (February 1, 2017): 363–80. http://dx.doi.org/10.5194/tc-11-363-2017.
Full textAbstract:
Abstract. Bed topography is a critical boundary for the numerical modelling of ice sheets and ice–ocean interactions. A persistent issue with existing topography products for the bed of the Greenland Ice Sheet and surrounding sea floor is the poor representation of coastal bathymetry, especially in regions of floating ice and near the grounding line. Sparse data coverage, and the resultant coarse resolution at the ice–ocean boundary, poses issues in our ability to model ice flow advance and retreat from the present position. In addition, as fjord bathymetry is known to exert strong control on ocean circulation and ice–ocean forcing, the lack of bed data leads to an inability to model these processes adequately. Since the release of the last complete Greenland bed topography–bathymetry product, new observational bathymetry data have become available. These data can be used to constrain bathymetry, but many fjords remain completely unsampled and therefore poorly resolved. Here, as part of the development of the next generation of Greenland bed topography products, we present a new method for constraining the bathymetry of fjord systems in regions where data coverage is sparse. For these cases, we generate synthetic fjord geometries using a method conditioned by surveys of terrestrial glacial valleys as well as existing sinuous feature interpolation schemes. Our approach enables the capture of the general bathymetry profile of a fjord in north-west Greenland close to Cape York, when compared to observational data. We validate our synthetic approach by demonstrating reduced overestimation of depths compared to past attempts to constrain fjord bathymetry. We also present an analysis of the spectral characteristics of fjord centrelines using recently acquired bathymetric observations, demonstrating how a stochastic model of fjord bathymetry could be parameterised and used to create different realisations.
41
Hoppmann, Mario, Ivan Kuznetsov, Ying-Chih Fang, and Benjamin Rabe. "Mesoscale observations of temperature and salinity in the Arctic Transpolar Drift: a high-resolution dataset from the MOSAiC Distributed Network." Earth System Science Data 14, no. 11 (November 4, 2022): 4901–21. http://dx.doi.org/10.5194/essd-14-4901-2022.
Full textAbstract:
Abstract. Measurements targeting mesoscale and smaller-scale processes in the ice-covered part of the Arctic Ocean are sparse in all seasons. As a result, there are significant knowledge gaps with respect to these processes, particularly related to the role of eddies and fronts in the coupled ocean–atmosphere–sea ice system. Here we present a unique observational dataset of upper ocean temperature and salinity collected by a set of buoys installed on ice floes as part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) Distributed Network. The multi-sensor systems, each equipped with five temperature and salinity recorders on a 100 m long inductive modem tether, drifted together with the main MOSAiC ice camp through the Arctic Transpolar Drift between October 2019 and August 2020. They transmitted hydrographic in situ data via the iridium satellite network at 10 min intervals. While three buoys failed early due to ice dynamics, five of them recorded data continuously for 10 months. A total of four units were successfully recovered in early August 2020, additionally yielding internally stored instrument data at 2 min intervals. The raw data were merged, processed, quality controlled, and validated using independent measurements also obtained during MOSAiC. Compilations of the raw and processed datasets are publicly available at https://doi.org/10.1594/PANGAEA.937271 (Hoppmann et al., 2021i) and https://doi.org/10.1594/PANGAEA.940320 (Hoppmann et al., 2022i), respectively. As an important part of the MOSAiC physical oceanography program, this unique dataset has many synergies with the manifold co-located observational datasets and is expected to yield significant insights into ocean processes and to contribute to the validation of high-resolution numerical simulations. While this dataset has the potential to contribute to submesoscale process studies, this paper mainly highlights selected preliminary findings on mesoscale processes.
42
Sakamoto, Masami, and John R. Christy. "The Influences of TOVS Radiance Assimilation on Temperature and Moisture Tendencies in JRA-25 and ERA-40." Journal of Atmospheric and Oceanic Technology 26, no. 8 (August 1, 2009): 1435–55. http://dx.doi.org/10.1175/2009jtecha1193.1.
Full textAbstract:
Abstract A Japanese long-term reanalysis (JRA-25) was completed in 2006 utilizing the comprehensive set of observations from the 40-yr ECMWF Re-Analysis (ERA-40). JRA-25 and ERA-40 adopted the same type of assimilation systems: 3DVAR with direct use of satellite sounding radiances. Long-term upper-air thermal tendencies in both reanalyses are examined and compared with the observational deep-layer temperatures of the University of Alabama in Huntsville (UAH) and Remote Sensing Systems (RSS). The upper-air temperature tendencies in the reanalyses are significantly different from those of UAH and RSS, and they appear to be influenced by the way the observations of the Television and Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) are used. This study focuses on documenting problems in TOVS assimilation, especially problems in bias corrections used in the reanalyses. Referring to quantitative results in an examination of biases between the reanalyses and raw TOVS observations, this study identifies (i) spurious thermal tendencies derived from transitions in TOVS and in the reanalysis calculation streams, (ii) an excessive enhancement of the tropical water cycle in ERA-40, and (iii) an excessive cooling trend and unstable behavior in the stratospheric temperature in JRA-25. The results of this study suggest that any inconsistencies in TOVS usage can lead to serious inconsistencies in the reanalyses. Therefore, time-consuming efforts to obtain reliable observational information from TOVS are necessary for further progress in reanalyses.
43
Carvalho, Lucélia Nobre, Rafael Arruda, and Jansen Zuanon. "Record of cleaning behavior by Platydoras costatus (Siluriformes: Doradidae) in the Amazon Basin, Brazil." Neotropical Ichthyology 1, no. 2 (December 2003): 137–39. http://dx.doi.org/10.1590/s1679-62252003000200009.
Full textAbstract:
Records of cleaning symbiosis between freshwater fish are scarce. Here we report on juvenile catfish, Platydoras costatus, cleaning the piscivorous characin Hoplias cf. malabaricus in a stream of the rio Araguaia drainage in the Brazilian Amazon. The scarcity of records on cleaning behavior in freshwater systems seems to be in part a consequence of the few observational studies under natural conditions in the Neotropics. Otherwise, the rareness of this behavior in freshwaters is possibly related to the short evolutionary time available to the fish fauna to develop these complex interactions, when compared to the ocean environment.
44
Subramaniyam, Narayan Puthanmadam, Reik V. Donner, Davide Caron, Gabriella Panuccio, and Jari Hyttinen. "Causal coupling inference from multivariate time series based on ordinal partition transition networks." Nonlinear Dynamics 105, no. 1 (June 18, 2021): 555–78. http://dx.doi.org/10.1007/s11071-021-06610-0.
Full textAbstract:
AbstractIdentifying causal relationships is a challenging yet crucial problem in many fields of science like epidemiology, climatology, ecology, genomics, economics and neuroscience, to mention only a few. Recent studies have demonstrated that ordinal partition transition networks (OPTNs) allow inferring the coupling direction between two dynamical systems. In this work, we generalize this concept to the study of the interactions among multiple dynamical systems and we propose a new method to detect causality in multivariate observational data. By applying this method to numerical simulations of coupled linear stochastic processes as well as two examples of interacting nonlinear dynamical systems (coupled Lorenz systems and a network of neural mass models), we demonstrate that our approach can reliably identify the direction of interactions and the associated coupling delays. Finally, we study real-world observational microelectrode array electrophysiology data from rodent brain slices to identify the causal coupling structures underlying epileptiform activity. Our results, both from simulations and real-world data, suggest that OPTNs can provide a complementary and robust approach to infer causal effect networks from multivariate observational data.
45
Hirth, Brian D., John L. Schroeder, W. Scott Gunter, and Jerry G. Guynes. "Measuring a Utility-Scale Turbine Wake Using the TTUKa Mobile Research Radars." Journal of Atmospheric and Oceanic Technology 29, no. 6 (June 1, 2012): 765–71. http://dx.doi.org/10.1175/jtech-d-12-00039.1.
Full textAbstract:
Abstract Observations of the wake generated by a single utility-scale turbine and collected by the Texas Tech University Ka-band mobile research radars on 27 October 2011 are introduced. Remotely sensed turbine wake observations using lidar technology have proven effective; however, the presented radar capabilities provide a larger observational footprint and greater along-beam resolution than current scanning lidar systems. Plan-position indicator and range–height indicator scanning techniques are utilized to produce various wake analyses. Preliminary analyses confirm radial velocity and wind speed deficits immediately downwind of the turbine hub to be on the order of 50%. This introduction lays the groundwork for more in-depth analyses of wake structure and evolution using the Texas Tech University Ka-band radar systems, including wake meandering and wake-to-wake interaction in large wind park deployments.
46
de Freitas Ramos Jacinto, Larissa, Luiz Claudio Gomes Pimentel, José Francisco de Oliveira Júnior, Ian Cunha D’Amato Viana Dragaud, Corbiniano Silva, William Cossich Marcial de Farias, Edilson Marton, et al. "Thermally and Dynamically Driven Atmospheric Circulations over Heterogeneous Atmospheric Boundary Layer: Support for Safety Protocols and Environment Management at Nuclear Central Areas." Atmosphere 12, no. 10 (October 9, 2021): 1321. http://dx.doi.org/10.3390/atmos12101321.
Full textAbstract:
Ilha Grande Bay is located in Angra dos Reis, Rio de Janeiro State, Brazil. The area is characterized by different land cover, complex topography and proximity to the Atlantic Ocean. These aspects make it susceptible to thermally and dynamically induced atmospheric circulations such as those associated with valley/mountain and land/sea breeze systems, among others. The Almirante Álvaro Alberto Nuclear Complex (CNAAA) is located in this region, with a total of two nuclear power plants (NPPs) in operation in the Brazilian territory, Angra I and Angra II. Therefore, knowledge of local atmospheric circulation has become a matter of national and international security. Considering the importance of the meteorological security tool as a support for licensing, installation, routine operation and nuclear accident mitigation, the main aim of this study is the development of combined strategies of environmental statistical modeling in the analysis of thermally and dynamically driven atmospheric circulations over mountainous and coastal environments. We identified and hierarchized the influence of the thermally and mechanically driven forcing on the wind regime and stability conditions in the coastal atmospheric boundary layer over the complex topography region. A meteorological network of ground-based instruments was used along with physiographic information for the observational characterization of the atmospheric patterns in the spatial and time–frequency domain. The predominant wind directions and intensity are attributed to the combined action of multiscale weather systems, notably, the valley/mountain and continent/ocean breeze circulations, the forced channeling due to valley axis orientation, the influence of the synoptic scale systems and atmospheric thermal tide. The observational investigation of the combined influence of terrain effects and meteorological systems aimed to understand the local atmospheric circulation serves as support for safety protocols of the NPPs, contemplating operation and environmental management. The importance of the study for the adequacy and skill evaluation of computational modeling systems for atmospheric dispersion of pollutants such as radionuclide and conventional contaminants can be also highlighted, in order that such systems are used as tools for environmental planning and managing nuclear operations, particularly those located in regions over mountainous and coastal environments with a heterogeneous atmospheric boundary layer.
47
Yaremchuk, Max. "Sparse Approximation of the Precision Matrices for the Wide-Swath Altimeters." Remote Sensing 14, no. 12 (June 13, 2022): 2827. http://dx.doi.org/10.3390/rs14122827.
Full textAbstract:
The upcoming technology of wide-swath altimetry from space will deliver a large volume of data on the ocean surface at unprecedentedly high spatial resolution. These data are contaminated by errors caused by the uncertainties in the geometry and orientation of the on-board interferometer and environmental conditions, such as sea surface roughness and atmospheric state. Being highly correlated along and across the swath, these errors present a certain challenge for accurate processing in operational data assimilation centers. In particular, the error covariance matrix R of the Surface Water and Ocean Topography (SWOT) mission may contain trillions of elements for a transoceanic swath segment at kilometer resolution, and this makes its handling a computationally prohibitive task. Analysis presented here shows, however, that the SWOT precision matrix R−1 and its symmetric square root can be efficiently approximated by a sparse block-diagonal matrix within an accuracy of a few per cent. A series of observational system experiments with simulated data shows that such approximation comes at the expense of a relatively minor reduction in the assimilation accuracy, and, therefore, could be useful in operational systems targeted at the retrieval of submesoscale variability of the ocean surface.
48
Berkson, Jonathan M., Arthur A. Allen, Donald L. Murphy, and Kenneth J. Boda. "Integrated Ocean Observing System (IOOS®) Supports Marine Operations: A Look from the U.S. Coast Guard." Marine Technology Society Journal 44, no. 6 (November 1, 2010): 156–65. http://dx.doi.org/10.4031/mtsj.44.6.22.
Full textAbstract:
AbstractThe U.S. Coast Guard (USCG) is primarily a user of ocean observations but is also a provider of observations—especially in high-latitude regions. USCG has a long history of making ocean observations for mission activities and in support of other federal agencies. USCG uses the Integrated Ocean Observing System (IOOS®) to understand maritime conditions while conducting the Coast Guard’s roles of Maritime Safety, Maritime Security, and Maritime Stewardship. IOOS data are critical in planning search and rescue operations, ensuring safe navigation at high latitudes, responding to oil and hazardous spills, providing vessel traffic services, and maintaining maritime domain awareness (MDA). The International Ice Patrol makes and uses ocean observations to estimate drift and deterioration of icebergs. The North American Ice Service products are needed in polar and domestic ice operations. The National Oceanic Atmospheric Administration and the USCG are developing a way to disseminate the Physical Oceanographic Real-Time System data via the USCG Automatic Identification System. The Coast Guard provides personnel and vessel support for the National Data Buoy Center observational program, a component of the IOOS. Many key oceanographic, biologic, and geologic discoveries in the Arctic and Antarctic have been made from Coast Guard cutters. As oceanographic data acquisition moves from vessel observations to satellite remote sensing and unmanned in situ data acquisition systems, the USCG will continue to support this effort.
49
Li, Rui, Jianxin He, Shunxian Tang, Fang Miao, and Xingang Fan. "Observational Consistency Comparison and Analyses of an X-Band Solid-State Radar and an X-Band Klystron Doppler Radar." Journal of Atmospheric and Oceanic Technology 34, no. 10 (October 2017): 2177–202. http://dx.doi.org/10.1175/jtech-d-16-0220.1.
Full textAbstract:
AbstractSolid-state weather radar transmitters offer great potential for increased reliability and maintainability, which have been proven to be critical for practical use. Although they have been implemented in radar systems, solid-state transmitters are incapable of producing as high peak power as available in klystrons. The pulse compression technique coupled with mismatched methods allows for low peak-power transmission and can improve the range-resolution and detection performance on the receiving end of a radar system. However, applying solid-state transmitters with pulse compression in weather radar systems still requires strong evidence for data reliability. With side-by-side observational experiments, this study compares a solid-state weather radar with the combined-pulse transmission mode to a close-by klystron Doppler weather radar in an attempt to 1) analyze the capability of the solid-state radar to reduce the near-range blind zone and 2) validate the quality and reliability of data from a solid-state radar that is implemented with the pulse compression technique. The data from the klystron Doppler weather radar are considered accurate and are used as a reference for quantitatively evaluating the solid-state radar data quality and reliability. Comparisons and statistics show that the observations from the solid-state radar are consistent with that from the klystron Doppler weather radar, especially in heavy rainfall. Results from the analysis indicate that the solid-state weather radar has high estimation accuracy in both near and far ranges.
50
Onken, Reiner, Heinz-Volker Fiekas, Laurent Beguery, Ines Borrione, Andreas Funk, Michael Hemming, Jaime Hernandez-Lasheras, et al. "High-resolution observations in the western Mediterranean Sea: the REP14-MED experiment." Ocean Science 14, no. 2 (April 26, 2018): 321–35. http://dx.doi.org/10.5194/os-14-321-2018.
Full textAbstract:
Abstract. The observational part of the REP14-MED experiment was conducted in June 2014 in the Sardo-Balearic Basin west of Sardinia (western Mediterranean Sea). Two research vessels collected high-resolution oceanographic data by means of hydrographic casts, towed systems, and underway measurements. In addition, a vast amount of data was provided by a fleet of 11 ocean gliders, time series were available from moored instruments, and information on Lagrangian flow patterns was obtained from surface drifters and one profiling float. The spatial resolution of the observations encompasses a spectrum over 4 orders of magnitude from 𝒪(101 m) to 𝒪(105 m), and the time series from the moored instruments cover a spectral range of 5 orders from 𝒪(101 s) to 𝒪(106 s). The objective of this article is to provide an overview of the huge data set which has been utilised by various studies, focusing on (i) water masses and circulation, (ii) operational forecasting, (iii) data assimilation, (iv) variability of the ocean, and (v) new payloads for gliders.