Добірка наукової літератури з теми "Earch convection"

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Статті в журналах з теми "Earch convection"

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Liu, Zijing, Min Min, Jun Li, Fenglin Sun, Di Di, Yufei Ai, Zhenglong Li, et al. "Local Severe Storm Tracking and Warning in Pre-Convection Stage from the New Generation Geostationary Weather Satellite Measurements." Remote Sensing 11, no. 4 (February 13, 2019): 383. http://dx.doi.org/10.3390/rs11040383.

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Анотація:
Accurate and prior identification of local severe storm systems in pre-convection environments using geostationary satellite imagery measurements is a challenging task. Methodologies for “convective initiation” identification have already been developed and explored for operational nowcasting applications; however, warning of such convective systems using the new generation of geostationary satellite imagery measurements in pre-convection environments is still not well studied. In this investigation, the Random Forest (RF) machine learning algorithm is used to develop a predictive statistical model for tracking and identifying three different types of convective storm systems (weak, medium, and severe) over East Asia by combining spatially-temporally collocated Himawari-8 (H08) measurements and Numerical Weather Prediction (NWP) forecast data. The Global Precipitation Measurement (GPM) gridded product is used as a benchmark to train the predictive models based on a sample-balance technique which can adjust or balance the samples of three different convection types to avoid over-fitting any type of dataset. Variables such as brightness temperatures (BTs) from H08 water vapor absorption bands (6.2 μm, 6.9 μm and 7.3 μm) and Total Precipitable Water (TPW) from NWP show relatively high ranks in the predictive model training. These sensitive variables are closely associated with convectively dominated precipitation areas, indicating the importance of predictors from both H08 and NWP data. The final optimal RF model is achieved with an accuracy of 0.79 for classification of all convective storm systems, while the Probability of Detection (POD) of this model for severe and medium convections can reach 0.66 and 0.70, respectively. Two typical sudden convective storm cases in the warm season of 2018 tracked by this algorithm are described, and results indicate that the H08 and NWP based statistical model using the RF algorithm is capable of capturing local burst convective storm systems about 1–2 h earlier than the outbreak of heavy rainfall.
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Zheng, Zhang, Liu, Liu, and Che. "A Study of Vertical Structures and Microphysical Characteristics of Different Convective Cloud–Precipitation Types Using Ka-Band Millimeter Wave Radar Measurements." Remote Sensing 11, no. 15 (August 1, 2019): 1810. http://dx.doi.org/10.3390/rs11151810.

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Millimeter wave cloud radar (MMCR) is one of the primary instruments employed to observe cloud–precipitation. With appropriate data processing, measurements of the Doppler spectra, spectral moments, and retrievals can be used to study the physical processes of cloud–precipitation. This study mainly analyzed the vertical structures and microphysical characteristics of different kinds of convective cloud–precipitation in South China during the pre-flood season using a vertical pointing Ka-band MMCR. Four kinds of convection, namely, multi-cell, isolated-cell, convective–stratiform mixed, and warm-cell convection, are discussed herein. The results show that the multi-cell and convective–stratiform mixed convections had similar vertical structures, and experienced nearly the same microphysical processes in terms of particle phase change, particle size distribution, hydrometeor growth, and breaking. A forward pattern was proposed to specifically characterize the vertical structure and provide radar spectra models reflecting the different microphysical and dynamic features and variations in different parts of the cloud body. Vertical air motion played key roles in the microphysical processes of the isolated- and warm-cell convections, and deeply affected the ground rainfall properties. Stronger, thicker, and slanted updrafts caused heavier showers with stronger rain rates and groups of larger raindrops. The microphysical parameters for the warm-cell cloud–precipitation were retrieved from the radar data and further compared with the ground-measured results from a disdrometer. The comparisons indicated that the radar retrievals were basically reliable; however, the radar signal weakening caused biases to some extent, especially for the particle number concentration. Note that the differences in sensitivity and detectable height of the two instruments also contributed to the compared deviation.
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Huang, Yipeng, Murong Zhang, Yuchun Zhao, Ben Jong-Dao Jou, Hui Zheng, Changrong Luo, and Dehua Chen. "Inter-Zone Differences of Convective Development in a Convection Outbreak Event over Southeastern Coast of China: An Observational Analysis." Remote Sensing 14, no. 1 (December 29, 2021): 131. http://dx.doi.org/10.3390/rs14010131.

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Анотація:
Among the densely-populated coastal areas of China, the southeastern coast has received less attention in convective development despite having been suffering from significantly increasing thunderstorm activities. The convective complexity under such a region with extremely complex underlying and convective conditions deserves in-depth observational surveys. This present study examined a high-impact convection outbreak event with over 40 hail reports in the southeastern coast of China on 6 May 2020 by focusing on contrasting the convective development (from convective initiation to supercell occurrences) among three adjacent convection-active zones (north (N), middle (M), and south (S)). The areas from N to S featured overall flatter terrain, higher levels of free convection, lower relative humidity, larger convective inhibition, more convective available potential energy, and greater vertical wind shears. With these mesoscale environmental variations, distinct inter-zone differences in the convective development were observed with the region’s surveillance radar network and the Himawari-8 geostationary satellite. Convection initiated in succession from N to S and began with more warm-rain processes in N and M and more ice-phase processes in S. The subsequent convection underwent more vigorous vertical growth from N to S. The extremely deep convection in S was characterized by the considerably strong precipitation above the freezing level, echo tops of up to 18 km, and a great amount of deep (even overshooting) and thick convective clouds with significant cloud-top glaciation. Horizontal anvil expansion in convective clouds was uniquely apparent over S. From N to S, more pronounced mesocyclone and weak-echo region signatures indicated high risks of severe supercell hailstorms. These results demonstrate the strong linkage between the occurrence likelihood of severe convection and associated weather (such as supercells and hailstones) and the early-stage convective development that can be well-captured by high-resolution observations and may facilitate fine-scale convection nowcasting.
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Lai, Anwei, Jinzhong Min, Jidong Gao, Hedi Ma, Chunguang Cui, Yanjiao Xiao, and Zhibin Wang. "Assimilation of Radar Data, Pseudo Water Vapor, and Potential Temperature in a 3DVAR Framework for Improving Precipitation Forecast of Severe Weather Events." Atmosphere 11, no. 2 (February 9, 2020): 182. http://dx.doi.org/10.3390/atmos11020182.

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An improved approach to derive pseudo water vapor mass mixing ratio and in- cloud potential temperature was developed in this paper to better initialize numerical weather prediction (NWP) and build convective-scale predictions of severe weather events. The process included several steps. The first was to identify areas of deep moist convection, utilizing Vertically Integrated Liquid water (VIL) derived from a mosaicked 3D radar reflectivity field. Then, pseudo- water vapor and pseudo- in- cloud potential temperature observations were derived based on the VIL. For potential temperature, the latent heat initialization for stratiform cloud and moist adiabatic initialization for deep moist convection were used based on a cloud analysis method. The third step was to assimilate the derived pseudo- water vapor and potential temperature observations, together with radar radial velocity and reflectivity into a convective-scale NWP model during data assimilation cycles spanning several hours. Finally, 3-h forecasts were launched each hour during the data assimilation period. The effects of radar data and pseudo- observation assimilation on the prediction of rainfall associated with convective systems surrounding the Meiyu front in 2018 were explored using two real cases. Two sets of experiments, each including several experiments in each real case, were designed to compare the effects of assimilation radar and pseudo- observations on the ensuing forecasts. Relative to the control experiment without data assimilation and radar experiment, the analyses and forecasts of convections were found to be improved for the two Meiyu front cases after pseudo- water vapor and potential temperature information was assimilated.
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Palotai, Csaba, Shawn Brueshaber, Ramanakumar Sankar, and Kunio Sayanagi. "Moist Convection in the Giant Planet Atmospheres." Remote Sensing 15, no. 1 (December 30, 2022): 219. http://dx.doi.org/10.3390/rs15010219.

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The outer planets of our Solar System display a myriad of interesting cloud features, of different colors and sizes. The differences between the types of observed clouds suggest a complex interplay between the dynamics and chemistry at play in these atmospheres. Particularly, the stark difference between the banded structures of Jupiter and Saturn vs. the sporadic clouds on the ice giants highlights the varieties in dynamic, chemical and thermal processes that shape these atmospheres. Since the early explorations of these planets by spacecrafts, such as Voyager and Voyager 2, there are many outstanding questions about the long-term stability of the observed features. One hypothesis is that the internal heat generated during the formation of these planets is transported to the upper atmosphere through latent heat release from convecting clouds (i.e., moist convection). In this review, we present evidence of moist convective activity in the gas giant atmospheres of our Solar System from remote sensing data, both from ground- and space-based observations. We detail the processes that drive moist convective activity, both in terms of the dynamics as well as the microphysical processes that shape the resulting clouds. Finally, we also discuss the effects of moist convection on shaping the large-scale dynamics (such as jet structures on these planets).
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Nakagawa, Takashi, and Shun-ichiro Karato. "Influence of realistic rheological properties on the style of mantle convection: roles of dynamic friction and depth-dependence of rheological properties." Geophysical Journal International 226, no. 3 (May 11, 2021): 1986–96. http://dx.doi.org/10.1093/gji/ggab197.

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SUMMARY In order to generate plate tectonics, the near surface layer should not be too strong, but the causes for not-so-strong near surface layer remains unclear. We conduct mantle convection modelling in the spherical geometry to investigate the influence of the strength of the near surface layer. We explore a range of friction coefficients including the static high friction coefficient (∼0.6) as well as the reduced friction coefficients by fast fault motion in earthquakes. When the friction coefficient is low enough (<0.03), the surface layer is yielded by the convective stress, and the style of mantle convection appears the mobile-lid mode (plate tectonics style of convection). This style is relevant for the Earth where fault motion is unstable because of the low surface temperature. In contrast, for a high friction coefficient, the surface layer is too strong, generating the stagnant-lid mode. This case corresponds to Venus where fault motion is stable because of high surface temperature. Our calculations show that, in plate tectonic style of convection, the mantle convection is likely to be more vigorous, inducing the high convective stress that helps the operation of plate tectonics. In contrast, when stagnant-lid mode of convection appears, the convective vigor is likely to be low, inducing the low convective stress. Therefore, in each case, the interplay between the surface strength and convective stress tends to maintain the same mode of convection in a self-consistent way. We also investigate the relationship between mantle temperature and heat flux for two different modes of convection upon a change in friction coefficient. We found that the heat flow associated with mobile lid convection caused by low friction is less sensitive to the mantle temperature compared to a conventional mantle convection model, where the heat flow is highly sensitive to mantle temperature. This provides a possible mechanism to solve the thermal runaway paradox.
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Anders, Evan H., Adam S. Jermyn, Daniel Lecoanet, J. R. Fuentes, Lydia Korre, Benjamin P. Brown, and Jeffrey S. Oishi. "Convective Boundary Mixing Processes." Research Notes of the AAS 6, no. 2 (February 28, 2022): 41. http://dx.doi.org/10.3847/2515-5172/ac5892.

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Abstract Convective motions extend beyond the nominal boundaries of a convection zone. These motions mix fluid through multiple mechanisms collectively called “convective boundary mixing.” In this note, we discuss three distinct fluid dynamical processes: convective overshoot, entrainment, and penetrative convection. We describe the structure of a convective boundary that these processes create. To resolve discrepancies between models and observations, the stellar astrophysics community should distinguish between these processes and parameterize each of them separately in 1D evolutionary models.
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Arango-Reyes, Karen, Marco Barranco-Jiménez, Gonzalo Ares de Parga-Álvarez, and Fernando Angulo-Brown. "A Simple Thermodynamic Model of the Internal Convective Zone of the Earth." Entropy 20, no. 12 (December 18, 2018): 985. http://dx.doi.org/10.3390/e20120985.

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Анотація:
As it is well known both atmospheric and mantle convection are very complex phenomena. The dynamical description of these processes is a very difficult task involving complicated 2-D or 3-D mathematical models. However, a first approximation to these phenomena can be by means of simplified thermodynamic models where the restriction imposed by the laws of thermodynamics play an important role. An example of this approach is the model proposed by Gordon and Zarmi in 1989 to emulate the convective cells of the atmospheric air by using finite-time thermodynamics (FTT). In the present article we use the FTT Gordon-Zarmi model to coarsely describe the convection in the Earth’s mantle. Our results permit the existence of two layers of convective cells along the mantle. Besides the model reasonably reproduce the temperatures of the main discontinuities in the mantle, such as the 410 km-discontinuity, the Repetti transition zone and the so-called D-Layer.
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Richardson, Mark T., Brian H. Kahn, and Peter Kalmus. "Trajectory enhancement of low-earth orbiter thermodynamic retrievals to predict convection: a simulation experiment." Atmospheric Chemistry and Physics 23, no. 13 (July 13, 2023): 7699–717. http://dx.doi.org/10.5194/acp-23-7699-2023.

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Abstract. The 3-D fields of temperature (T) and specific humidity (q) retrieved by instruments such as the Atmospheric Infrared Sounder (AIRS) are predictive of convection, but convection often triggers during the multi-hour gaps between satellite overpasses. Here we fill the hours after AIRS overpasses by treating AIRS retrievals as air parcels which are moved adiabatically along numerical weather prediction (NWP) wind trajectories. The approach is tested in a simulation experiment that samples 3-D European Reanalysis-5 (ERA5) T and q following the real-world AIRS time–space sampling from March–November 2019 over much of the continental US. Our time-resolved product is named ERA5-FCST, in correspondence to the AIRS forecast product we are using it to test, named AIRS-FCST. ERA5-FCST errors may arise since processes such as radiative heating and NWP sub-grid convection are ignored. For bulk atmospheric layers, ERA5-FCST captures 59 %–94 % of local hourly variation in T and q. We then consider the relationship between convective available potential energy (CAPE), convective inhibition (CIN), and ERA5 precipitation. The 1∘ latitude–longitude ERA5-FCST grid cells in our highest CAPE and lowest CIN bins are more than 50 times as likely to develop heavy precipitation (> 4 mm hr−1), compared with the baseline probability from randomly selecting a location. This is a substantial improvement compared with using the original CAPE and CIN values at overpass time. The results support the development of similar FCST products for operational atmospheric sounders to provide time-resolved thermodynamics in rapidly changing pre-convective atmospheres.
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Rybka, H., and H. Tost. "Uncertainties in future climate predictions due to convection parameterisations." Atmospheric Chemistry and Physics Discussions 13, no. 10 (October 16, 2013): 26893–931. http://dx.doi.org/10.5194/acpd-13-26893-2013.

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Abstract. In the last decades several convection parameterisations have been developed to consider the impact of small-scale unresolved processes in Earth System Models associated with convective clouds. Global model simulations, which have been performed under current climate conditions with different convection schemes, significantly differ among each other in the simulated transport of trace gases and precipitation patterns due to the parameterisation assumptions and formulations, e.g. the simplified treatment of the cloud microphysics. Here we address sensitivity studies comparing four different convection schemes under alternative climate conditions (doubling of the CO2 concentrations) to identify uncertainties related to convective processes. The increase in surface temperature reveals regional differences up to 4 K dependent on the chosen convection parameterisation. The increase in upper tropospheric temperature affects the amount of water vapour transported to the lower stratosphere. Furthermore, the change in transporting short-lived pollutants within the atmosphere is highly ambiguous for the lower and upper troposphere. Finally, cloud radiative effects have been analysed uncovering a shift in different cloud types in the tropics.
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Дисертації з теми "Earch convection"

1

Rostami, Masoud. "Dynamical influence of diabatic processes upon developing instabilities of Earth and planetary jets and vortices." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066186.

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Le but de la thèse est de comprendre l'influence dynamique des effets diabatiques, comme la convection humide, sur les instabilités des vortex atmosphériques terrestres et planétaires. Un modèle verticalement intégré, avec les paramétrisations type relaxation des transitions de phase et de dégagement de la chaleur latente, le modèle de St-Venant avec la convection humide, a été utilisé. La version précédente du modèle a été améliorée pour inclure l'eau précipitable, sa vaporisation et son entrainement. L'approche consiste en 1) analyse détaillée de stabilité des profils idéalisés, ou extraits des données, des vortex, 2) étude de saturation non-linéaire des instabilités à l'aide de schéma numérique de haute résolution aux volumes finis. Les résultats principaux de la thèse sont : 1. Démonstration et quantification d'une forte influence des effets humides sur les instabilités des vortex synoptiques, y compris asymétrie cyclone-anticyclone des vortex de faible intensité aux latitudes moyennes, et de l'intensification des vortex type cyclones tropicaux, avec formation des nuages caractéristiques. 2. Explication de l'origine dynamique de l'hexagone au pôle Nord de Saturne, et de l'absence de structure similaire au pôle Sud, en termes d'instabilité du système vortex polaire - jet circumpolaire, et sa saturation non-linéaire. 3. Explication de la structure observée du vortex polaire hivernal sur Mars en termes d'instabilité et sa saturation en présence de réchauffement /refroidissement radiatif et de déposition de CO2 (transition de phase gaz - solide). Une nouvelle paramétrisation simple a été proposée pour ce processus, incluant l'influence des noyaux de déposition
The thesis is devoted to understanding dynamical influence of diabatic effects, like moist convection, on instabilities of vortices in Earth and planetary atmospheres. A vertically integrated atmospheric model with relaxational parameterisation of phase transitions and related heat release, and with convective fluxes included in mass and momentum equations, the moist-convective rotating shallow water model, was used for this purpose. The previous version of the model was improved to include precipitable water and its vaporisation and entrainment. The approach consists in 1)detailed stability analysis of idealised, or extracted from the data, vortex profiles, 2)study of nonlinear saturation of the instabilities with the help of finite-volume high-resolution numerical code. The main results of the thesis are: 1. Demonstration and quantification of strong influence of moist effects upon instabilities of synoptic vortices, including cyclone-anticyclone asymmetry of mid-latitude vortices of weak intensity, and intensification of tropical-cyclone like vortices with formation of typical cloud patterns. 2. Explanation of the dynamical origin of the Saturn's North Polar hexagon, and of the lack of similar structure at the South Pole, in terms of instability of the coupled polar vortex and circumpolar jet, and their nonlinear saturation.3. Explanation of the observed structure of Mars' winter polar vortex in terms of instability of the latter, and its saturation in the presence of radiative heating/cooling and CO2 deposition (gas-solid phase transition). A new simple parameterisation of the latter process, including the influence of deposition nuclei, was developed in the thesis
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2

Hall, Paul S. "Free and forced convection in earth's upper mantle /." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3115631.

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3

Park, Sewon. "Diurnal cycle of deep tropical convection." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/54985.

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Анотація:
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1992.
Title as it appears in the M.I.T. Graduate List, Feb. 1992: Diurnal cycle of deep cloud cover in tropics.
Includes bibliographical references (leaf 53).
by Sewon Park.
M.S.
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4

Kocha, Cécile. "Interactions entre poussières désertiques et convection profonde en Afrique de l'Ouest : Observations et modélisation à échelle convective." Phd thesis, Université Paul Sabatier - Toulouse III, 2011. http://tel.archives-ouvertes.fr/tel-00741943.

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Анотація:
Dans un contexte de réchauffement climatique, la région d'Afrique de l'Ouest, où les sécherresses sont dévastatrices pour les populations, montre les plus fortes incertitudes sur l'évolution des précipitations. C'est aussi la première source de poussières désertiques au monde dont la production est en augmentation par la sur-exploitation des sols. Or ces poussières désertiques, associées à des épidémies de méningite, absorbent et diffusent le flux solaire entraînant alors une modification du taux d'échauffement atmosphérique. En modifiant le bilan radiatif atmosphérique elles sont alors succeptible d'influencer de la turbulence de fine échelle aux circulations atmosphériques de grande échelle. Seulement les processus en jeu dans les interactions entre les poussières désertiques et l'atmosphère sont très variés, complexes, et constituent une grande source d'incertitude dans la prévision numérique. Afin d'appréhender ces processus, un cadre de modélisation à été développé permettant à la fois la résolution explicite de la convection, la résolution du cycle de vie des poussières et de leur impact radiatif, et la prise en compte de leurs interactions sur toute l'Afrique de l'Ouest à échelle mensuelle. Sur un cas extrême de tempête de poussières en saison sèche, la forte quantité de poussières soulevée par le front entraîne une amplification par eux de la signature de la tempête. La modélisation explicite des poussières améliore la prévisibilité de la tempête. De manière plus statistique, pendant la mise en place de la mousson, en juin, la fréquente présence de poussières participe activement à l'initiation du saut de mousson. D'une part, en affaiblissant la dépression thermique Saharienne, un des principaux moteurs de la mousson, mais aussi, d'autre part, en renforçant le déplacement vers le nord du coeur de la zone de convergence inter-tropicale et des jets. A plus fine échelle, la présence de poussières impacte la localisation et le cycle diurne des systèmes convectifs. Les poussières modifient alors la couverture nuageuse dont les impacts radiatifs sont plus forts que l'effet direct des poussières. La prise en compte des effets semi-directs des poussières sont donc essentiels pour la prévision en Afrique de l'Ouest.
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5

Alverson, Keith D. 1965. "Topographic preconditioning of open ocean deep convection." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/53023.

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Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1995.
Includes bibliographical references (leaves 143-146).
by Keith D. Alverson.
Ph.D.
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6

Amiri, Khanmakani Hosein. "The visible consequences of rising convective streams in the Earth." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336266.

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7

Boldi, Robert A. (Robert Arthur). "A model of ion chemistry of electrified convection." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/51502.

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Анотація:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1992.
Includes bibliographical references (leaves 175-182) and index.
by Robert A. Boldi.
Ph.D.
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8

Larson, Vincent Edwin 1970. "The effects of thermal radiation on dry convection." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/54433.

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Анотація:
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1999.
Includes bibliographical references (p. 96-99).
This work seeks to improve understanding of atmospheres in radiative-convective equilibrium. We use two types of idealized, dry radiative-convective models. The first type of model resembles Rayleigh-Benard convection, except that thermal radiative transfer is included. This type of system can be investigated in the laboratory. The second type of model is a more faithful representation of the earth's atmosphere. In this model, the temperature at the upper boundary is left unspecified, unlike the case of Rayleigh-Benard convection. For these two types of radiative-convective models, we perform various theoretical and numerical analyses of the stability properties, and various analyses of the weakly nonlinear convecting state. We prove that in these models, convection arises as monotonically growing cells, not as an oscillatory instability. That is, we prove exchange of stabilities. We investigate the linear stability modes. We find that in most cases, the linear stability threshold can be described approximately or exactly in terms of a radiative Rayleigh number. The radiative Rayleigh numbers used are like the classical Rayleigh number but with modified temperature and thermal diffusivity scales. Inspection of the radiative Rayleigh numbers reveals how various external parameters, such as the net incoming solar radiation or infrared opacity, affect the stability properties. We use the energy method to find a threshold value of a stability parameter below which all disturbances to the radiative equilibrium state, regardless of magnitude, decay. For those radiative equilibrium states which have a linear temperature profile, the energy stability threshold coincides with the linear stability threshold, thereby ruling out the possibility of subcritical instabilities. When the temperature profile is nonlinear, the energy stability profile lies below the linear stability threshold. We study weakly nonlinear convection in the atmospheric radiative-convective model via the mean field approximation. In contrast to the stability threshold, the vertical convective heat flux in the weakly nonlinear convecting state turns out to be little affected by the values of viscosity, thermal diffusivity, or radiative damping. However, the convective heat flux is strongly affected by the net incoming solar radiation and the optical depth. We formulate scaling laws for vertical convective heat flux, vertical velocity, and temperature perturbations. These scales extend the Prandtl scales to higher altitudes.
by Vincent Edwin Larson.
Ph.D.
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9

Bell, Peter Ian. "The effect of bumps on convection in the earth's core." Thesis, University of Newcastle Upon Tyne, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335890.

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10

de, Lavaissiere de Lavergne Casimir. "Cessation of southern ocean deep convection under anthropogenic climate change." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119766.

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In 1974, newly available satellite observations unveiled the presence of a giant ice-free area within the Antarctic ice pack, which persisted throughout the winter, and formed again in the next two winters. Subsequent research showed that deep convective overturning kept the waters ice-free, through the massive release of heat rising from the deep sea. While the polynya has aroused continued interest among climate scientists, it has not reappeared since 1976. Here we use model experiments to show that deep convection in the Southern Ocean, common in current generation climate models, is highly sensitive to anthropogenic forcing, and ceases in many models when forced by a high emissions climate change scenario. The slowdown in deep ventilation follows from the gradual freshening of polar surface waters, a trend which is borne out by observations over recent decades. Our results suggest that deep convection in the Southern Ocean will be less common in future, and may have already been significantly reduced compared to the pre-industrial period, with important consequences for ocean circulation and climate.
En 1974, des observations satellite nouvellement disponibles révélèrent la présence d'une géante surface d'eau libre au sein de la glace de mer entourant l'Antarctique, qui persista tout au long de l'hiver et réapparut les deux hivers suivants. Les recherches qui suivirent montrèrent que les eaux étaient maintenues libres de glace par la convection profonde, permettant à une grande quantité de chaleur de remonter des profondeurs pour être ensuite libérée dans l'atmosphère. Si la polynya continue de susciter l'intérêt des climatologues, elle n'est cependant pas réapparue depuis 1976. Nous utilisons ici des expériences de modélisation pour montrer que la convection profonde dans l'Océan Austral, commune dans les modèles de climat actuels, est fortement sensible au forçage anthropique, et cesse dans beaucoup de modèles quand ceux-ci sont forcés par un scénario de fortes émissions. Le ralentissement de la ventilation profonde résulte de la baisse progressive de la salinité des eaux de surface, une tendance corroborée par les observations des dernières décennies. Nos résultats suggèrent que la convection profonde dans l'Océan Austral sera moins fréquente dans le futur, et a peut-être déjà été significativement affaiblie relativement à la période préindustrielle, avec d'importantes conséquences pour la circulation océanique et le climat.
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Книги з теми "Earch convection"

1

Dynamic earth: Plates, plumes, and mantle convection. Cambridge: Cambridge University Press, 1999.

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2

Royal Society (Great Britain). Discussion Meeting. Chemical reservoirs and convection in the earth's mantle: Papers of a discussion meeting. London: The Royal Society, 2002.

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3

Van der Hilst, Robert D. (Robert Dirk), 1961-, ed. Earth's deep mantle: Structure, composition, and evolution. Washington, DC: American Geophysical Union, 2005.

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4

Erickson, Gary M. A mechanism for magnetospheric substorms. [Washington, D.C: National Aeronautics and Space Administration, 1994.

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5

Chassignet, Eric P. Buoyancy-driven flows. Cambridge: Cambridge University Press, 2012.

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6

United States. National Aeronautics and Space Administration. and Massachusetts Institute of Technology. Dept. of Earth, Atmospheric, and Planetary Sciences., eds. Lateral variation in upper mantle temperature and composition beneath mid-ocean ridges inferred from shear-wave propagation, geoid, and bathymetry. [Cambridge, Mass.]: Dept. of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 1991.

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7

A, Gnoffo Peter, and Langley Research Center, eds. Convective and radiative heating for vehicle return from the Moon and Mars. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1995.

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8

Wilson, Gordon R. The high latitude ionosphere-magnetosphere transition region: Simulation and data comparison. [Washington, D.C.]: National Aeronautics and Space Administration, 1995.

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9

Gordon, Howard R. Ocean observations with EOS/MODIS: Algorithm development and post launch studies : semi-annual report (for July - December 1995). [Washington, D.C: National Aeronautics and Space Administration, 1996.

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10

United States. National Aeronautics and Space Administration., ed. Ocean observations with EOS/MODIS: Algorithm development and post launch studies : semi-annual report (for January - June 1996), contract number NAS5-31363. [Washington, DC: National Aeronautics and Space Administration, 1996.

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Частини книг з теми "Earch convection"

1

Bercovici, David, and Elvira Mulyukova. "Mantle Convection." In Encyclopedia of Solid Earth Geophysics, 1–21. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-10475-7_130-1.

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2

Bercovici, David. "Mantle Convection." In Encyclopedia of Solid Earth Geophysics, 832–51. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-8702-7_130.

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3

Bercovici, David, and Elvira Mulyukova. "Mantle Convection." In Encyclopedia of Solid Earth Geophysics, 1059–79. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-58631-7_130.

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4

Kistovich, Anatoly. "Convective Motions in Water: Linear and Nonlinear Models, Criteria of Convection Onset." In Springer Proceedings in Earth and Environmental Sciences, 174–88. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-11533-3_18.

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5

Huppert, H. E., B. A. Buffett, J. R. Lister, and A. W. Woods. "Solidification and Convection in the Core of the Earth." In Interactive Dynamics of Convection and Solidification, 265–67. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2809-4_42.

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6

Davies, Geoffrey F. "Some Clarity: Two Convection Modes, Interacting." In Stories from the Deep Earth, 139–51. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-91359-5_12.

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7

Fedyushkin, A. I. "Stratification and Segregation Under Laminar Convection." In Advanced Hydrodynamics Problems in Earth Sciences, 153–69. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-23050-9_14.

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8

Singh, R. N., and A. Manglik. "Parameterized Mantle Convection Analysis for Crustal Processes." In Society of Earth Scientists Series, 75–88. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-06471-0_4.

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9

Sanchez, David A., Christopher Gonzalez, David A. Yuen, Grady B. Wright, and Gregory A. Barnett. "High Rayleigh Number Mantle Convection on GPU." In Lecture Notes in Earth System Sciences, 335–52. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-16405-7_22.

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10

Lin, Li Xi, and H. T. Hsu. "Excitement of the Toroidal Field in Mantle Convection." In Geodesy and Physics of the Earth, 291–98. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78149-0_68.

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Тези доповідей конференцій з теми "Earch convection"

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Timchenko, Victoria. "Eddie Leonardi Memorial Lecture: Natural Convection from Earth to Space." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23354.

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This lecture is dedicated to the memory of Professor Eddie Leonardi, formerly International Heat Transfer Conference (IHTC-13) Secretary, who tragically died at an early age on December 14, 2008. Eddie Leonardi had a large range of research interests: he worked in both computational fluid dynamics/heat transfer and refrigeration and air-conditioning for over 25 years. However starting from his PhD ‘A numerical Study of the effects of fluid properties on Natural Convection’ awarded in 1984, one of his main passions has been natural convection and therefore the focus of this lecture will be on what Eddie Leonardi has achieved in numerical and experimental investigations of laminar natural convective flows. A number of examples will be presented which illustrate important difficulties of numerical calculations and experimental comparisons. Eddie Leonardi demonstrated that variable properties have important effects and significant differences occur when different fluids are used, so that non-dimensionalisation is not an appropriate tool when dealing with fluids in thermally driven flows in which there are significant changes in transport properties. Difficulties in comparing numerical solutions with either numerically generated data or experimental results will be discussed with reference to two-dimensional natural convection and three-dimensional Rayleigh-Be´nard convection in bounded domains with conducting boundaries. For a number of years Eddie Leonardi was involved in a joint US-French-Australian research program — the MEPHISTO experiment on crystal growth — and studied the effects of convection on solidification and melting under microgravity conditions. The results of this research will be described. Finally, results of experimental and numerical studies of natural convection for Building Integrated Photovoltaic (BIPV) applications in which Eddie Leonardi had been working in the last few years will also be presented.
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2

Chang, Tiejun, Xiaoxiong Xiong, and Ashish Shrestha. "Assessment of MODIS TEB calibration performance using deep convective clouds." In Earth Observing Systems XXIV, edited by James J. Butler, Xiaoxiong (Jack) Xiong, and Xingfa Gu. SPIE, 2019. http://dx.doi.org/10.1117/12.2528043.

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3

Mu, Qiaozhen, Amit Angal, Aisheng Wu, and Xiaoxiong Xiong. "Performance assessment of the NOAA-20 VIIRS RSB using deep convective clouds." In Earth Observing Systems XXVI, edited by James J. Butler, Xiaoxiong (Jack) Xiong, and Xingfa Gu. SPIE, 2021. http://dx.doi.org/10.1117/12.2593514.

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4

Jeong, Gi Ho, Soo In Jeong, Kui Soon Kim, and Man Young Ha. "Numerical Analysis of Natural Convection and Phase Change Problem With Finite Volume Method." In ASME/JSME 2004 Pressure Vessels and Piping Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/pvp2004-3108.

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A numerical analysis is performed in this study to observe the phase change and natural convection problem occurring in the confined geometry. The unsteady, incompressible 3-D Navier-Stokes equation and energy equation have been considered as governing equation in this study. In addition, numerical tools based on finite volume method were developed and those were found to be tools to analyze phase change and natural convection problem with qualitative accuracy. For verification, phase interfacial lines and flow patterns were compared to previous studies and showed good agreements for the case of square cavity and extended cubic. For application, phase change and natural convection problem inside circular pipe were considered. With and without axial flow cases were compared with each other to observe the effect of axial flow on the flow pattern and phase change characteristics. It was found that the forced convective flow tends to disturb the formation of ice-plug and natural convective flow tends to promote the energy exchanges and expedite the formation of ice-plug.
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5

Chang, Tiejun, Carlos Pérez Díaz, Ashish Shrestha, and Xiaoxiong Xiong. "Application of quasi-deep convective clouds method for MODIS and VIIRS TEB calibration assessments." In Earth Observing Systems XXV, edited by James J. Butler, Xiaoxiong (Jack) Xiong, and Xingfa Gu. SPIE, 2020. http://dx.doi.org/10.1117/12.2567221.

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6

Both, J. W., S. E. Gasda, I. Aavatsmark, and R. Kaufmann. "Gravity-driven Convective Mixing of CO2 in Oil." In The Third Sustainable Earth Sciences Conference and Exhibition. Netherlands: EAGE Publications BV, 2015. http://dx.doi.org/10.3997/2214-4609.201414266.

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7

Colombani, Jean. "Microgravity and earth thermal diffusion in liquids holographic visualization of convection." In HADRONS AND NUCLEI: First International Symposium. AIP, 2000. http://dx.doi.org/10.1063/1.1302586.

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8

Wang, Xin, Ning Mei, Xijun Yu, and Yan Li. "A Method of Identifying the Ingredient of Homo-Zeotrope by Measurable Temperature Field of Pipe Convective Heat Transfer Model." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-62066.

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A method of identifying the composition of homo-zeotrope with measuring the pipe convective heat transfer temperature field is shown. In the case of the set pressure and low Reynolds number liquid, consider about the full development period of laminar pipe fluid mechanics characters, heat convection transfer temperature field could be known of numerical method with given model parameters. Calculating equation-controlling nonlinear simulation parameters by inverse problem of the convective heat transfer controlling equation, mix proportion can be worked out by the connection between estimating parameters values and the calculated total parameters of each element. Besides, process error analysis suggests the error of mix proportion in calculated parameters matches the given.
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9

Reynier, Philippe. "Convective Blockage for High-Speed Earth Entries: A Review." In 40th Thermophysics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2008. http://dx.doi.org/10.2514/6.2008-3806.

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10

Bhatt, Rajendra, David R. Doelling, Benjamin R. Scarino, Arun Gopalan, and Conor O. Haney. "Advances in utilizing tropical deep convective clouds as a stable target for on-orbit calibration of satellite imager reflective solar bands." In Earth Observing Systems XXIV, edited by James J. Butler, Xiaoxiong (Jack) Xiong, and Xingfa Gu. SPIE, 2019. http://dx.doi.org/10.1117/12.2530636.

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Звіти організацій з теми "Earch convection"

1

Gallagher, Alex, Sandra LeGrand, Taylor Hodgdon, and Theodore Letcher. Simulating environmental conditions for Southwest United States convective dust storms using the Weather Research and Forecasting Model v4.1. Engineer Research and Development Center (U.S.), August 2022. http://dx.doi.org/10.21079/11681/44963.

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Dust aerosols can pose a significant detriment to public health, transportation, and tactical operations through reductions in air quality and visibility. Thus, accurate model forecasts of dust emission and transport are essential to decision makers. While a large number of studies have advanced the understanding and predictability of dust storms, the majority of existing literature considers dust production and forcing conditions of the underlying meteorology independently of each other. Our study works to-wards filling this research gap by inventorying dust-event case studies forced by convective activity in the Desert Southwest United States, simulating select representative case studies using several configurations of the Weather Research and Forecasting (WRF) model, testing the sensitivity of forecasts to essential model parameters, and assessing overall forecast skill using variables essential to dust production and transport. We found our control configuration captured the initiation, evolution, and storm structure of a variety of convective features admirably well. Peak wind speeds were well represented, but we found that simulated events arrived up to 2 hours earlier or later than observed. Our results show that convective storms are highly sensitive to initialization time and initial conditions that can preemptively dry the atmosphere and suppress the growth of convective storms.
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2

Kedzierski, Mark A., and Donggyu Kang. Horizontal convective boiling of R1234yf, R134a, and R450A within a micro-fin tube :. Gaithersburg, MD: National Institute of Standards and Technology (U.S.), August 2017. http://dx.doi.org/10.6028/nist.tn.1966.

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This report presents local convective boiling heat transfer and Fanning friction factor measurements in a micro-fin tube for R134a and two possible low global warming potential (GWP) refrigerant replacements for R134a: R1234yf and R450A. Test section heating was achieved with water in either counterflow or in parallel flow with the test refrigerant to provide for a range of heat fluxes for each thermodynamic quality. An existing correlation from the literature for single and multi-component mixtures was shown to not satisfactorily predict the convective boiling measurements for flow qualities greater than 40 %. Accordingly, a new correlation was developed specifically for the test fluids of this study so that a fair comparison of the heat transfer performance of the low GWP refrigerants to that of R134a could be made. The new correlation was used to compare the heat transfer coefficient of the three test fluids at the same heat flux, saturated refrigerant temperature, and refrigerant mass flux. The resulting example comparison, for the same operating conditions, showed that the heat transfer coefficient of the multi-component R450A and the single-component R1234yf were, on average, 15 % less and 5 % less, respectively, than that of the single-component R134a. Friction factor measurements were also compared to predictions from an existing correlation. A new correlation for the friction factor was developed to provide a more accurate prediction. The measurements and the new models are important for the evaluation of potential low-GWP refrigerants replacements for R134a.
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3

Boily-Auclair, É., P. Mercier-Langevin, P. S. Ross, and D. Pitre. Alteration and ore assemblages of the LaRonde Zone 5 (LZ5) deposit and Ellison mineralized zones, Doyon-Bousquet-LaRonde mining camp, Abitibi, Quebec. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/329637.

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The LaRonde Zone 5 (LZ5) mine is part of the Doyon-Bousquet-LaRonde mining camp and is located in the southern part of the Abitibi greenstone belt in northwestern Quebec. The LZ5 deposit consists of three stacked mineralized corridors: Zone 4, Zone 4.1, and Zone 5. Zones 4 and 4.1 are discontinuous satellite mineralized corridors, whereas Zone 5 represents the main mineralized body. The mineralized zones of the LZ5 deposit and adjacent Ellison property (Ellison A and B zones) are hosted in the strongly-deformed, 2699-2695 Ma transitional to calcalkaline, intermediate to felsic, volcanic and volcaniclastic rocks of the Bousquet Formation upper member, which is part of the Blake River Group (2704-2695 Ma). Zones 4, 4.1, and 5 at the LZ5 mine are hosted in intermediate volcanic and volcaniclastic rocks of the Westwood andesitic to rhyodacitic unit (unit 5.1a), which forms the base of the upper member of the Bousquet Formation. The Ellison Zone A is hosted higher up in the stratigraphic sequence within a newly described intermediate volcanic unit. The Ellison Zone B is hosted in felsic volcanic and volcaniclastic rocks of the Westwood feldsparphyric rhyolite dome (subunit 5.3a-(b)). Mineralization in all three zones of the LZ5 deposit consists of discordant networks of millimeter- to centimeter-thick pyrite ±chalcopyrite ±sphalerite ±pyrrhotite veins and veinlets (10-20 % of the volume of the rock) and, to a lesser extent, very finely disseminated pyrite and boudinaged veins (less than or equal to 5 vol. % each) in strongly altered host rocks. Gold commonly occurs as microscopic inclusions in granoblastic pyrite and at the triple junction between recrystallized grains. The veins, stockworks, and disseminations were intensely folded and transposed in the steeply south-dipping, east-west trending S2 foliation. The vein network is at least partly discordant to the stratigraphy. A distal alteration halo envelops the LZ5 mineralized corridors and consists of a sericite-carbonate-chlorite- feldspar ±biotite assemblage. A proximal sericite-carbonate-chlorite-pyrite-quartz- feldspar-biotite ±epidote alteration assemblage is present within the LZ5 mineralized zones. A local proximal alteration assemblage of sericite-quartz-pyrite is also locally developed within Zone 4 and Zone 5 of the LZ5 deposit. Mass gains in Fe2O3 (t) and K2O, and mass losses in CaO, MgO, Na2O, and locally SiO2, are characteristic of the LZ5 alteration zones. The Ellison zone A and B are similar to LZ5 in terms of style of mineralization, but thin (10-20 cm) veins or bands of semi-massive to massive, finely recrystallized disseminated pyrite (0.1-1 mm) are distinctive. Chalcopyrite and sphalerite are also slightly more abundant in the mineralized corridors of the Ellison property and are usually associated with elevated gold grades. The zones are also slightly richer than at LZ5 in terms of gold and silver content, but narrower and less continuous in general. The Ellison Zone A is characterized by gains in Fe2O3 (t) and K2O and losses in CaO, MgO, Na2O, and SiO2. Gains in Fe2O3 (t) and local gains in K2O, MgO, and MnO, and losses in CO2, Na2O, P2O5, and SiO2, characterize the felsic host rocks of the Zone B corridor. The style of mineralization at LZ5 (pyrite ±chalcopyrite veins and veinlets, ±disseminated pyrite with low base metal content), its setting (i.e. in rocks of intermediate composition at the base of the upper member of the Bousquet Formation), and the geometry of its ore zones (stacked lenses of sulfide veins and veinlets, without massive sulfide lenses) differ from the other major deposits of the Doyon-Bousquet-LaRonde mining camp. Despite these differences, this study indicates that the LZ5 and Ellison mineralized corridors are of synvolcanic hydrothermal origin and have most likely been formed by convective circulation of seawater below the seafloor. An influx of magmatic fluids from the Mooshla synvolcanic intrusive complex or its parent magma chamber could explain the Au enrichment at LZ5, as has been suggested for other deposits of the camp. Evidence for a pre-deformation synvolcanic mineralization at LZ5 includes ductile deformation and recrystallization of the sulfides, the stacked nature of its ore zones, subconcordant alteration halos that envelop the mineralized corridors, evidence that the mineralized system was already active when the LZ5 lenses were deposited and control on mineralization by primary volcanic features such as the permeability and porosity of the volcanic rocks.
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