Journal articles on the topic 'Seasonal cycle'
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1
Crowley, Thomas J., John G. Mengel, and David A. Short. "Gondwanaland's seasonal cycle." Nature 329, no. 6142 (October 1987): 803–7. http://dx.doi.org/10.1038/329803a0.
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Fischer, Madlen, Henning W. Rust, and Uwe Ulbrich. "Seasonal Cycle in German Daily Precipitation Extremes." Meteorologische Zeitschrift 27, no. 1 (January 29, 2018): 3–13. http://dx.doi.org/10.1127/metz/2017/0845.
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Gilford, Daniel M., and Susan Solomon. "Radiative Effects of Stratospheric Seasonal Cycles in the Tropical Upper Troposphere and Lower Stratosphere." Journal of Climate 30, no. 8 (April 2017): 2769–83. http://dx.doi.org/10.1175/jcli-d-16-0633.1.
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Water vapor and ozone are powerful radiative constituents in the tropical lower stratosphere, impacting the local heating budget and nonlocally forcing the troposphere below. Their near-tropopause seasonal cycle structures imply associated “radiative seasonal cycles” in heating rates that could affect the amplitude and phase of the local temperature seasonal cycle. Overlying stratospheric seasonal cycles of water vapor and ozone could also play a role in the lower stratosphere and upper troposphere heat budgets through nonlocal propagation of radiation. Previous studies suggest that the tropical lower stratospheric ozone seasonal cycle radiatively amplifies the local temperature seasonal cycle by up to 35%, while water vapor is thought to have a damping effect an order of magnitude smaller. This study uses Aura Microwave Limb Sounder observations and an offline radiative transfer model to examine ozone, water vapor, and temperature seasonal cycles and their radiative linkages in the lower stratosphere and upper troposphere. Radiative sensitivities to ozone and water vapor vertical structures are explicitly calculated, which has not been previously done in a seasonal cycle context. Results show that the water vapor radiative seasonal cycle in the lower stratosphere is not sensitive to the overlying water vapor structure. In contrast, about one-third of ozone’s radiative seasonal cycle amplitude at 85 hPa is associated with longwave emission above 85 hPa. Ozone’s radiative effects are not spatially homogenous: for example, the Northern Hemisphere tropics have a seasonal cycle of radiative temperature adjustments with an amplitude 0.8 K larger than the Southern Hemisphere tropics.
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Mclaren, Craig H., and Xichuan (Mark) Zhang. "The Importance of Trend-Cycle Analysis for National Statistics Institutes." Studies of Applied Economics 28, no. 3 (March 14, 2021): 607–24. http://dx.doi.org/10.25115/eea.v28i3.4744.
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Seasonal adjustment is a widely applied statistical method. National Statistics Institutes around the world apply seasonal adjustment methods, such as X-12-ARIMA or TRAMO-SEATS, on a regular basis to help users interpret movements in the time series and aid in decision making. The seasonal adjustment process decomposes the original time series into three main components: a trend-cycle, seasonal and irregular. By definition the seasonally adjusted estimates still contain a degree of volatility as they are just a combination of the trend-cycle and irregular. Typically, as an analytical product, the seasonally adjusted estimates are published alongside the time series of the original estimates. In most countries the trend-cycle estimates are not published. Some countries, such as Australia, regularly publish trend-cycle as additional analytical product alongside the original and seasonally adjusted estimates to inform users. This paper presents the case for the regular calculation and production of trend- cycle estimates at National Statistics Institutes to help inform and educate users about the longer term signals in the time series.
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Barsky, Robert B., and Jeffrey A. Miron. "The Seasonal Cycle and the Business Cycle." Journal of Political Economy 97, no. 3 (June 1989): 503–34. http://dx.doi.org/10.1086/261614.
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Johri, Alok. "Markups and the seasonal cycle." Journal of Macroeconomics 23, no. 3 (June 2001): 367–95. http://dx.doi.org/10.1016/s0164-0704(01)00169-0.
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Liao, Ting, Charles D. Camp, and Yuk L. Yung. "The seasonal cycle of N2O." Geophysical Research Letters 31, no. 17 (September 2004): n/a. http://dx.doi.org/10.1029/2004gl020345.
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Stein, Karl, Niklas Schneider, Axel Timmermann, and Fei-Fei Jin. "Seasonal Synchronization of ENSO Events in a Linear Stochastic Model*." Journal of Climate 23, no. 21 (November 1, 2010): 5629–43. http://dx.doi.org/10.1175/2010jcli3292.1.
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Abstract A simple model of ENSO is developed to examine the effects of the seasonally varying background state of the equatorial Pacific on the seasonal synchronization of ENSO event peaks. The model is based on the stochastically forced recharge oscillator, extended to include periodic variations of the two main model parameters, which represent ENSO’s growth rate and angular frequency. Idealized experiments show that the seasonal cycle of the growth rate parameter sets the seasonal cycle of ENSO variance; the inclusion of the time dependence of the angular frequency parameter has a negligible effect. Event peaks occur toward the end of the season with the most unstable growth rate. Realistic values of the parameters are estimated from a linearized upper-ocean heat budget with output from a high-resolution general circulation model hindcast. Analysis of the hindcast output suggests that the damping by the mean flow field dominates the seasonal cycle of ENSO’s growth rate and, thereby, seasonal ENSO variance. The combination of advective, Ekman pumping, and thermocline feedbacks plays a secondary role and acts to enhance the seasonal cycle of the ENSO growth rate.
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Donohoe, Aaron, Eliza Dawson, Lynn McMurdie, David S. Battisti, and Andy Rhines. "Seasonal Asymmetries in the Lag between Insolation and Surface Temperature." Journal of Climate 33, no. 10 (May 15, 2020): 3921–45. http://dx.doi.org/10.1175/jcli-d-19-0329.1.
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AbstractWe analyze the temporal structure of the climatological seasonal cycle in surface air temperature across the globe. We find that, over large regions of Earth, the seasonal cycle of surface temperature departs from an annual harmonic: the duration of fall and spring differ by as much as 2 months. We characterize this asymmetry by the metric ASYM, defined as the phase lag of the seasonal maximum temperature relative to the summer solstice minus the phase lag of the seasonal minimum temperature relative to winter solstice. We present a global analysis of ASYM from weather station data and atmospheric reanalysis and find that ASYM is well represented in the reanalysis. ASYM generally features positive values over land and negative values over the ocean, indicating that spring has a longer duration over the land domain whereas fall has a longer duration over the ocean. However, ASYM also features more positive values over North America compared to Europe and negative values in the polar regions over ice sheets and sea ice. Understanding the root cause of the climatological ASYM will potentially further our understanding of controls on the seasonal cycle of temperature and its future/past changes. We explore several candidate mechanisms to explain the spatial structure of ASYM including 1) modification of the seasonal cycle of surface solar radiation by the seasonal evolution of cloud thickness, 2) differences in the seasonal cycle of the atmospheric boundary layer depth over ocean and over land, and 3) temperature advection by the seasonally evolving atmospheric circulation.
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Ryu, Young-Hee, James A. Smith, and Elie Bou-Zeid. "On the Climatology of Precipitable Water and Water Vapor Flux in the Mid-Atlantic Region of the United States." Journal of Hydrometeorology 16, no. 1 (February 1, 2015): 70–87. http://dx.doi.org/10.1175/jhm-d-14-0030.1.
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Abstract The seasonal and diurnal climatologies of precipitable water and water vapor flux in the mid-Atlantic region of the United States are examined. A new method of computing water vapor flux at high temporal resolution in an atmospheric column using global positioning system (GPS) precipitable water, radiosonde data, and velocity–azimuth display (VAD) wind profiles is presented. It is shown that water vapor flux exhibits striking seasonal and diurnal cycles and that the diurnal cycles exhibit rapid transitions over the course of the year. A particularly large change in the diurnal cycle of meridional water vapor flux between spring and summer seasons is found. These features of the water cycle cannot be resolved by twice-a-day radiosonde observations. It is also shown that precipitable water exhibits a pronounced seasonal cycle and a less pronounced diurnal cycle. There are large contrasts in the climatology of water vapor flux between precipitation and nonprecipitation conditions in the mid-Atlantic region. It is hypothesized that the seasonal transition of large-scale flow environments and the change in the degree of differential heating in the mountainous and coastal areas are responsible for the contrasting diurnal cycle between spring and summer seasons.
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Hindrayanto, Irma, Jan P. A. M. Jacobs, Denise R. Osborn, and Jing Tian. "TREND–CYCLE–SEASONAL INTERACTIONS: IDENTIFICATION AND ESTIMATION." Macroeconomic Dynamics 23, no. 8 (February 6, 2018): 3163–88. http://dx.doi.org/10.1017/s1365100517001092.
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Economists typically use seasonally adjusted data in which the assumption is imposed that seasonality is uncorrelated with trend and cycle. The importance of this assumption has been highlighted by the Great Recession. The paper examines an unobserved components model that permits nonzero correlations between seasonal and nonseasonal shocks. Identification conditions for estimation of the parameters are discussed from the perspectives of both analytical and simulation results. Applications to UK household consumption expenditures and US employment reject the zero correlation restrictions and also show that the correlation assumptions imposed have important implications about the evolution of the trend and cycle in the post-Great Recession period.
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Jucker, M., S. Fueglistaler, and G. K. Vallis. "Maintenance of the Stratospheric Structure in an Idealized General Circulation Model." Journal of the Atmospheric Sciences 70, no. 11 (October 31, 2013): 3341–58. http://dx.doi.org/10.1175/jas-d-12-0305.1.
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Abstract This work explores the maintenance of the stratospheric structure in a primitive equation model that is forced by a Newtonian cooling with a prescribed radiative equilibrium temperature field. Models such as this are well suited to analyze and address questions regarding the nature of wave propagation and troposphere–stratosphere interactions. The focus lies on the lower to midstratosphere and the mean annual cycle, with its large interhemispheric variations in the radiative background state and forcing, is taken as a benchmark to be simulated with reasonable verisimilitude. A reasonably realistic basic stratospheric temperature structure is a necessary first step in understanding stratospheric dynamics. It is first shown that using a realistic radiative background temperature field based on radiative transfer calculations substantially improves the basic structure of the model stratosphere compared to previously used setups. Then, the physical processes that are needed to maintain the seasonal cycle of temperature in the lower stratosphere are explored. It is found that an improved stratosphere and seasonally varying topographically forced stationary waves are, in themselves, insufficient to produce a seasonal cycle of sufficient amplitude in the tropics, even if the topographic forcing is large. Upwelling associated with baroclinic wave activity is an important influence on the tropical lower stratosphere and the seasonal variation of tropospheric baroclinic activity contributes significantly to the seasonal cycle of the lower tropical stratosphere. Given a reasonably realistic basic stratospheric structure and a seasonal cycle in both stationary wave activity and tropospheric baroclinic instability, it is possible to obtain a seasonal cycle in the lower stratosphere of amplitude comparable to the observations.
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Atkinson, C. P., H. L. Bryden, J. J.-M. Hirschi, and T. Kanzow. "On the seasonal cycles and variability of Florida Straits, Ekman and Sverdrup transports at 26° N in the Atlantic Ocean." Ocean Science 6, no. 4 (October 1, 2010): 837–59. http://dx.doi.org/10.5194/os-6-837-2010.
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Abstract. Since April 2004 the RAPID array has made continuous measurements of the Atlantic Meridional Overturning Circulation (AMOC) at 26° N. Two key components of this system are Ekman transport zonally integrated across 26° N and western boundary current transport in the Florida Straits. Whilst measurements of the AMOC as a whole are somewhat in their infancy, this study investigates what useful information can be extracted on the variability of the Ekman and Florida Straits transports using the decadal timeseries already available. Analysis is also presented for Sverdrup transports zonally integrated across 26° N. The seasonal cycles of Florida Straits, Ekman and Sverdrup transports are quantified at 26° N using harmonic analysis of annual and semi-annual constituents. Whilst Sverdrup transport shows clear semi-annual periodicity, calculations of seasonal Florida Straits and Ekman transports show substantial interannual variability due to contamination by variability at non-seasonal frequencies; the mean seasonal cycle for these transports only emerges from decadal length observations. The Florida Straits and Ekman mean seasonal cycles project on the AMOC with a combined peak-to-peak seasonal range of 3.5 Sv. The combined seasonal range for heat transport is 0.40 PW. The Florida Straits seasonal cycle possesses a smooth annual periodicity in contrast with previous studies suggesting a more asymmetric structure. No clear evidence is found to support significant changes in the Florida Straits seasonal cycle at sub-decadal periods. Whilst evidence of wind driven Florida Straits transport variability is seen at sub-seasonal and annual periods, a model run from the 1/4° eddy-permitting ocean model NEMO is used to identify an important contribution from internal oceanic variability at sub-annual and interannual periods. The Ekman transport seasonal cycle possesses less symmetric structure, due in part to different seasonal transport regimes east and west of 50 to 60° W. Around 60% of non-seasonal Ekman transport variability occurs in phase section-wide at 26° N and is related to the NAO, whilst Sverdrup transport variability is more difficult to decompose.
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Atkinson, C. P., H. L. Bryden, J. J. M. Hirschi, and T. Kanzow. "On the variability of Florida Straits and wind driven transports at 26° N in the Atlantic Ocean." Ocean Science Discussions 7, no. 2 (April 29, 2010): 919–71. http://dx.doi.org/10.5194/osd-7-919-2010.
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Abstract. Since April 2004 the RAPID array has made continuous measurements of the Atlantic Meridional Overturning Circulation (AMOC) at 26° N. Two key components of this system are Ekman transport zonally integrated across 26° N and western boundary current transport in the Florida Straits. Whilst measurements of the AMOC as a whole are somewhat in their infancy, this study investigates what useful information can be extracted on the variability of the Ekman and Florida Straits transports using the decadal timeseries already available. Analysis is also presented for Sverdrup transports zonally integrated across 26° N. The seasonal cycles of Florida Straits, Ekman and Sverdrup transports are quantified at 26° N using harmonic analysis of annual and semi-annual constituents. Whilst Sverdrup transport shows clear semi-annual periodicity, calculations of seasonal Florida Straits and Ekman transports show substantial interannual variability due to variability at non-seasonal frequencies; the mean seasonal cycle for these transports only emerges from decadal length observations. The Florida Straits and Ekman mean seasonal cycles project on the AMOC with a combined peak-to-peak seasonal range of 3.5 Sv. The combined seasonal range for heat transport is 0.40 PW. The Florida Straits seasonal cycle possesses a smooth annual periodicity in contrast with previous studies suggesting a more asymmetric structure. No clear evidence is found to support significant changes in the Florida Straits seasonal cycle at sub-decadal periods. Whilst evidence of wind driven Florida Straits transport variability is seen at sub-seasonal and annual periods, model runs from the 1/4° eddy-permitting ocean model NEMO are used to identify an important contribution from internal oceanic variability at sub-annual and interannual periods. The Ekman transport seasonal cycle possesses less symmetric structure, due in part to different seasonal transport regimes east and west of 50 to 60° W. Around 60% of non-seasonal Ekman transport variability occurs in phase section-wide at 26° N and is related to the NAO, whilst Sverdrup transport variability is more difficult to decompose.
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Assel, Raymond A. "Classification of Annual Great Lakes Ice Cycles: Winters of 1973–2002*." Journal of Climate 18, no. 22 (November 15, 2005): 4895–905. http://dx.doi.org/10.1175/jcli3571.1.
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Abstract Annual seasonal average ice cover from 1973 to 2002 and associated dates of first ice, last ice, and ice duration are presented and discussed. The annual seasonal average ice cover of each Great Lake is used to define three ice cycle classes: mild, typical, and severe. About half of the severe ice cycles occurred from 1977 to 1982 and about half of the mild ice cycles occurred from 1998 to 2002. The seasonal progression of daily lake-averaged ice cover, spatial differences in ice cover, and differences among the Great Lakes for mild, typical, and severe ice cycles are discussed within the context of lake bathymetry and winter air temperatures. Seasonal average ice cover is larger on Lakes Superior, Erie, and Huron relative to Lakes Michigan and Ontario, because of shallower depths (for Erie and Huron) and lower air temperatures (for Superior) relative to Lakes Michigan and Ontario. This ice cycle classification scheme can be used to compare future Great Lakes ice cycle severity with this 30-winter benchmark.
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Mongwe, N. Precious, Marcello Vichi, and Pedro M. S. Monteiro. "The seasonal cycle of <i>p</i>CO<sub>2</sub> and CO<sub>2</sub> fluxes in the Southern Ocean: diagnosing anomalies in CMIP5 Earth system models." Biogeosciences 15, no. 9 (May 15, 2018): 2851–72. http://dx.doi.org/10.5194/bg-15-2851-2018.
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Abstract. The Southern Ocean forms an important component of the Earth system as a major sink of CO2 and heat. Recent studies based on the Coupled Model Intercomparison Project version 5 (CMIP5) Earth system models (ESMs) show that CMIP5 models disagree on the phasing of the seasonal cycle of the CO2 flux (FCO2) and compare poorly with available observation products for the Southern Ocean. Because the seasonal cycle is the dominant mode of CO2 variability in the Southern Ocean, its simulation is a rigorous test for models and their long-term projections. Here we examine the competing roles of temperature and dissolved inorganic carbon (DIC) as drivers of the seasonal cycle of pCO2 in the Southern Ocean to explain the mechanistic basis for the seasonal biases in CMIP5 models. We find that despite significant differences in the spatial characteristics of the mean annual fluxes, the intra-model homogeneity in the seasonal cycle of FCO2 is greater than observational products. FCO2 biases in CMIP5 models can be grouped into two main categories, i.e., group-SST and group-DIC. Group-SST models show an exaggeration of the seasonal rates of change of sea surface temperature (SST) in autumn and spring during the cooling and warming peaks. These higher-than-observed rates of change of SST tip the control of the seasonal cycle of pCO2 and FCO2 towards SST and result in a divergence between the observed and modeled seasonal cycles, particularly in the Sub-Antarctic Zone. While almost all analyzed models (9 out of 10) show these SST-driven biases, 3 out of 10 (namely NorESM1-ME, HadGEM-ES and MPI-ESM, collectively the group-DIC models) compensate for the solubility bias because of their overly exaggerated primary production, such that biologically driven DIC changes mainly regulate the seasonal cycle of FCO2.
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Chen, Gang, and Lantao Sun. "Mechanisms of the Tropical Upwelling Branch of the Brewer–Dobson Circulation: The Role of Extratropical Waves." Journal of the Atmospheric Sciences 68, no. 12 (December 1, 2011): 2878–92. http://dx.doi.org/10.1175/jas-d-11-044.1.
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Abstract The role of extratropical waves in the tropical upwelling branch of the Brewer–Dobson circulation is investigated in an idealized model of the stratosphere and troposphere. To simulate different stratospheric seasonal cycles of planetary waves in the two hemispheres, seasonally varying radiative heating is imposed only in the stratosphere, and surface topographic forcing is prescribed only in the Northern Hemisphere (NH). A zonally symmetric version of the same model is used to diagnose the effects of different wavenumbers and different regions of the total forcing on tropical stratospheric upwelling. The simple configuration can simulate a reasonable seasonal cycle of the tropical upwelling in the lower stratosphere with a stronger amplitude in January (NH midwinter) than in July (NH midsummer), as in the observations. It is shown that the seasonal cycle of stratospheric planetary waves and tropical upwelling responds nonlinearly to the strength of the tropospheric forcing, with a midwinter maximum under strong NH-like tropospheric forcing and double peaks in the fall and spring under weak Southern Hemisphere (SH)-like forcing. The planetary wave component of the total forcing can approximately reproduce the seasonal cycle of tropical stratospheric upwelling in the zonally symmetric model. The zonally symmetric model further demonstrates that the planetary wave forcing in the winter tropical and subtropical stratosphere contributes most to the seasonal cycle of tropical stratospheric upwelling, rather than the high-latitude wave forcing. This suggests that the planetary wave forcing, prescribed mostly in the extratropics in the model, has to propagate equatorward into the subtropical latitudes to induce sufficient tropical upwelling. Another interesting finding is that the planetary waves in the summer lower stratosphere can drive a shallow residual circulation rising in the subtropics and subsiding in the extratropics.
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Cubadda, Gianluca, Giovanni Savio, and Roberto Zelli. "SEASONALITY, PRODUCTIVITY SHOCKS, AND SECTORAL COMOVEMENTS IN A REAL BUSINESS CYCLE MODEL FOR ITALY." Macroeconomic Dynamics 6, no. 3 (June 2002): 337–56. http://dx.doi.org/10.1017/s1365100500000316.
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This paper investigates the degree of comovements in quarterly Italian time series of sectoral output. A recently developed multivariate technique for the empirical analysis of long-run, cyclical and seasonal comovements is used in the context of a multisectoral real-business-cycle model augmented with persistent seasonal shocks in productivity. Our empirical results emphasize the role of input–output relations in the propagation mechanism and indicate that sectoral outputs have a relatively low number of common stochastic trends, in conflict with the hypothesis of independent productivity shocks. In contrast, stochastic seasonals seem to move idiosyncratically. Furthermore, our findings suggest that the theoretical model should be extended to allow for deterministic seasonal shifts in preferences.
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Chertkova, Elena, and Victoria Sizova. "Production and Technological Parameters of Milled Peat Extraction Depending on Organization of Peat Machines Operation." E3S Web of Conferences 105 (2019): 01002. http://dx.doi.org/10.1051/e3sconf/201910501002.
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The article presents two options of organizing the technological process of milled peat extraction with due consideration of weather conditions for peat drying. The first option of the technological process is the extraction based on cycle peat harvesting differentiation. The developed technological process of milled peat drying in thick layers based on pneumatic peat harvesting allows us to organize a technology of peat extraction with a constant cycle time, avoiding the necessity for drying rate prediction. This is due to the fact that under good weather conditions the spreading thickness of 45-50 mm is sufficient to maximize the number of harvesting cycles. Milling at roughly equal depths forms the basis for the second option of technological process. The article presents the methodology of calculating such technological parameters as cycle and seasonal harvesting, number of cycles and seasonal productivity of a harvesting machine. Seasonal harvesting and seasonal productivity of a harvesting machine are calculated by technological design standards. The analysis of calculations revealed that in the process of milled peat extraction based on cycle harvesting differentiation, it is necessary to apply coefficient 0.9 that takes into account the organization of harvesting machines operation.
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Uehling, John, and Vasubandhu Misra. "Characterizing the Seasonal Cycle of the Northern Australian Rainy Season." Journal of Climate 33, no. 20 (October 15, 2020): 8957–73. http://dx.doi.org/10.1175/jcli-d-19-0592.1.
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AbstractIn this paper we introduce an objective definition for the onset and the retreat of the northern Australian rainy season that overlaps significantly with the Australian monsoon season. We define onset and retreat dates of the northern Australian rainy season as being the first and the last day of the year when the daily rain rate exceeds and falls below the climatological annual mean rain rate, respectively. However, our definition of onset/demise is not as restrictive as the traditional monsoon season that seeks the arrival of the westerlies and the equatorward retreat of the trough at its onset and demise, respectively. As defined in this paper, the length of the rainy season is longer than the monsoon season and includes the pre- and post-monsoon rainfall. It is noted that an early or later onset date of the northern Australian rainy season is associated with a longer or shorter, wetter or drier, and colder or warmer season, respectively. Similar relationship is also observed with demise date variations, which are, however, weaker than the onset date variations. Furthermore, we find that the relationship of the northern Australian seasonal rainfall variations with ENSO variability becomes stronger when we account for variations in the length of the rainy season compared to the fixed (December–February) monsoon season length. We also find a significant linear trend over the time period of the analysis from 1901 to 2015 toward an increasing length of the northern Australian rainy season that influences the corresponding rising trend of seasonal rainfall anomalies.
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Liu, Yonggang, Jun Yang, Huiming Bao, Bing Shen, and Yongyun Hu. "Large equatorial seasonal cycle during Marinoan snowball Earth." Science Advances 6, no. 23 (June 2020): eaay2471. http://dx.doi.org/10.1126/sciadv.aay2471.
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In the equatorial regions on Earth today, the seasonal cycle of the monthly mean surface air temperature is <10°C. However, deep (>1 m) sand wedges were found near the paleoequator in the Marinoan glaciogenic deposits at ~635 million years ago, indicating a large seasonal cycle (probably >30°C). Through numerical simulations, we show that the equatorial seasonal cycle could reach >30°C at various continental locations if the oceans are completely frozen over, as would have been the case for a snowball Earth, or could reach ~20°C if the oceans are not completely frozen over, as would have been the case for a waterbelt Earth. These values are obtained at the maximum eccentricity of the Earth orbit, i.e., 0.0679, and will be approximately 10°C smaller if the present-day eccentricity is used. For these seasonal cycles, theoretical calculations show that the deep sand wedges form readily in a snowball Earth while hardly form in a waterbelt Earth.
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Houben, Howard, Robert M. Haberle, Richard E. Young, and Aaron P. Zent. "Modeling the Martian seasonal water cycle." Journal of Geophysical Research: Planets 102, E4 (April 1, 1997): 9069–83. http://dx.doi.org/10.1029/97je00046.
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Schertzer, W. M., J. H. Saylor, F. M. Boyce, D. G. Robertson, and F. Rosa. "Seasonal Thermal Cycle of Lake Erie." Journal of Great Lakes Research 13, no. 4 (January 1987): 468–86. http://dx.doi.org/10.1016/s0380-1330(87)71667-0.
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Palumbo, A., and A. Mazzarella. "Seasonal cycle of mean sea-level." Il Nuovo Cimento C 8, no. 3 (May 1985): 273–81. http://dx.doi.org/10.1007/bf02574713.
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Beaulieu, J. Joseph, and Jeffrey A. Miron. "The seasonal cycle in U.S. manufacturing." Economics Letters 37, no. 2 (October 1991): 115–18. http://dx.doi.org/10.1016/0165-1765(91)90117-4.
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Brannigan, Liam, David P. Marshall, Alberto Naveira-Garabato, and A. J. George Nurser. "The seasonal cycle of submesoscale flows." Ocean Modelling 92 (August 2015): 69–84. http://dx.doi.org/10.1016/j.ocemod.2015.05.002.
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Partonen, Timo. "Metabolic syndrome follows a seasonal cycle." Hypertension Research 33, no. 6 (April 16, 2010): 534. http://dx.doi.org/10.1038/hr.2010.51.
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Rehwagen, M., U. Schlink, and O. Herbarth. "Seasonal cycle of VOCs in apartments." Indoor Air 13, no. 3 (September 2003): 283–91. http://dx.doi.org/10.1034/j.1600-0668.2003.00206.x.
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Chiang, John C. H., and Anthony J. Broccoli. "Orbital eccentricity and Earth’s seasonal cycle." PLOS Climate 3, no. 7 (July 2, 2024): e0000436. http://dx.doi.org/10.1371/journal.pclm.0000436.
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Arístegui, Javier, Santiago Hernández-León, María F. Montero, and May Gómez. "The seasonal planktonic cycle in coastal waters of the Canary Islands." Scientia Marina 65, S1 (July 30, 2001): 51–58. http://dx.doi.org/10.3989/scimar.2001.65s151.
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van Schaick Zillesen, Pieter G. "Seasonal Synchronization of the Life-Cycle of Pterostichus oblongopunctatus (Coleoptera: Carabidae)." Entomologia Generalis 11, no. 1-2 (December 1, 1985): 33–39. http://dx.doi.org/10.1127/entom.gen/11/1985/33.
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Maier, Gerhard. "The seasonal cycle of Metacyclops gracilis (LILLJEBORG) in a shallow pond." Archiv für Hydrobiologie 115, no. 1 (March 23, 1989): 97–110. http://dx.doi.org/10.1127/archiv-hydrobiol/115/1989/97.
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Tackenberg, Michael C., Jacob J. Hughey, and Douglas G. McMahon. "Distinct Components of Photoperiodic Light Are Differentially Encoded by the Mammalian Circadian Clock." Journal of Biological Rhythms 35, no. 4 (June 11, 2020): 353–67. http://dx.doi.org/10.1177/0748730420929217.
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Seasonal light cycles influence multiple physiological functions and are mediated through photoperiodic encoding by the circadian system. Despite our knowledge of the strong connection between seasonal light input and downstream circadian changes, less is known about the specific components of seasonal light cycles that are encoded and induce persistent changes in the circadian system. Using combinations of 3 T cycles (23, 24, 26 h) and 2 photoperiods per T cycle (long and short, with duty cycles scaled to each T cycle), we investigate the after-effects of entrainment to these 6 light cycles. We measure locomotor behavior duration (α), period (τ), and entrained phase angle (ψ) in vivo and SCN phase distribution (σφ), τ, and ψ ex vivo to refine our understanding of critical light components for influencing particular circadian properties. We find that both photoperiod and T-cycle length drive determination of in vivo ψ but differentially influence after-effects in α and τ, with photoperiod driving changes in α and photoperiod length and T-cycle length combining to influence τ. Using skeleton photoperiods, we demonstrate that in vivo ψ is determined by both parametric and nonparametric components, while changes in α are driven nonparametrically. Within the ex vivo SCN, we find that ψ and σφ of the PER2∷LUCIFERASE rhythm follow closely with their likely behavioral counterparts (ψ and α of the locomotor activity rhythm) while also confirming previous reports of τ after-effects of gene expression rhythms showing negative correlations with behavioral τ after-effects in response to T cycles. We demonstrate that within-SCN σφ changes, thought to underlie α changes in vivo, are induced primarily nonparametrically. Taken together, our results demonstrate that distinct components of seasonal light input differentially influence ψ, α, and τ and suggest the possibility of separate mechanisms driving the persistent changes in circadian behaviors mediated by seasonal light.
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Donohoe, Aaron, and David S. Battisti. "The Seasonal Cycle of Atmospheric Heating and Temperature." Journal of Climate 26, no. 14 (July 12, 2013): 4962–80. http://dx.doi.org/10.1175/jcli-d-12-00713.1.
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Abstract The seasonal cycle of the heating of the atmosphere is divided into a component due to direct solar absorption in the atmosphere and a component due to the flux of energy from the surface to the atmosphere via latent, sensible, and radiative heat fluxes. Both observations and coupled climate models are analyzed. The vast majority of the seasonal heating of the northern extratropics (78% in the observations and 67% in the model average) is due to atmospheric shortwave absorption. In the southern extratropics, the seasonal heating of the atmosphere is entirely due to atmospheric shortwave absorption in both the observations and the models, and the surface heat flux opposes the seasonal heating of the atmosphere. The seasonal cycle of atmospheric temperature is surface amplified in the northern extratropics and nearly barotropic in the Southern Hemisphere; in both cases, the vertical profile of temperature reflects the source of the seasonal heating. In the northern extratropics, the seasonal cycle of atmospheric heating over land differs markedly from that over the ocean. Over the land, the surface energy fluxes complement the driving absorbed shortwave flux; over the ocean, they oppose the absorbed shortwave flux. This gives rise to large seasonal differences in the temperature of the atmosphere over land and ocean. Downgradient temperature advection by the mean westerly winds damps the seasonal cycle of heating of the atmosphere over the land and amplifies it over the ocean. The seasonal cycle in the zonal energy transport is 4.1 PW. Finally, the authors examine the change in the seasonal cycle of atmospheric heating in 11 models from phase 3 of the Coupled Model Intercomparison Project (CMIP3) due to a doubling of atmospheric carbon dioxide from preindustrial concentrations. The seasonal heating of the troposphere is everywhere enhanced by increased shortwave absorption by water vapor; it is reduced where sea ice has been replaced by ocean, which increases the effective heat storage reservoir of the climate system and thereby reduces the seasonal magnitude of energy fluxes between the surface and the atmosphere. As a result, the seasonal amplitude of temperature increases in the upper troposphere (where atmospheric shortwave absorption increases) and decreases at the surface (where the ice melts).
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Zeng, Ning. "Seasonal cycle and interannual variability in the Amazon hydrologic cycle." Journal of Geophysical Research: Atmospheres 104, no. D8 (April 1, 1999): 9097–106. http://dx.doi.org/10.1029/1998jd200088.
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Fursov, V. V., G. I. Tayukin, and M. V. Balyura. "STRUCTURAL DEFORMATION OF FUEL AND CHEMICAL REFINER OBJECTS IN SEASONAL SOIL FREEZING." Vestnik Tomskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. JOURNAL of Construction and Architecture 22, no. 5 (October 31, 2020): 187–99. http://dx.doi.org/10.31675/1607-1859-2020-22-5-187-199.
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The paper presents the analysis of deformation caused by seasonal freezing and thawing of clay foundation soils during the construction of construction industry bases, waste treatment facilities and others, etc. The deformation generation and development during a single freezingthawing cycle and long-term cycles are discussed depending on the foundation depth of seasonally freezing soil, foundation pressure and other factors. It is shown that soil setting during thawing of the frozen soil significantly exceeds its bulging during freezing. Recommendations are given on the reduction and prevention of inadmissible deformations, and structural restoration and reinforcement. The advantages of pile foundations are shown against the natural foundations in seasonal soil freezing conditions.
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Thomalla, S. J., N. Fauchereau, S. Swart, and P. M. S. Monteiro. "Regional scale characteristics of the seasonal cycle of chlorophyll in the Southern Ocean." Biogeosciences Discussions 8, no. 3 (May 13, 2011): 4763–804. http://dx.doi.org/10.5194/bgd-8-4763-2011.
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Abstract. The seasonal cycle is the mode that couples climate forcing to ecosystem production. A better understanding of the regional characteristics of the seasonal cycle addresses an important gap in our understanding of the sensitivity of the biological pump to climate change. The regional characteristics of the seasonal cycle of phytoplankton biomass in the Southern Ocean were examined in terms of the timing of the bloom initiation, its amplitude, regional scale variability and the importance of the climatological seasonal cycle in explaining the overall variance. The study highlighted important differences between the spatial distribution of satellite observed phytoplankton biomass and the more dynamically linked characteristics of the seasonal cycle. The seasonal cycle was consequently defined into four broad zonal regions; the subtropical zone (STZ), the transition zone (TZ), the Antarctic circumpolar zone (ACZ) and the marginal ice zone (MIZ). Defining the Southern Ocean according to the characteristics of its seasonal cycle provides a more dynamic understanding of ocean productivity based on underlying physical drivers rather than climatological biomass. The response of the biology to the underlying physics of the different seasonal zones resulted in an additional classification of four regions based on the extent of interannual seasonal phase locking and the amplitude of the integrated seasonal biomass. This characterisation contributes to an improved understanding of regional sensitivity to climate forcing potentially allowing more robust predictions of long term climate trends.
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Nevison, C. D., E. Dlugokencky, G. Dutton, J. W. Elkins, P. Fraser, B. Hall, P. B. Krummel, et al. "Abiotic and biogeochemical signals derived from the seasonal cycles of tropospheric nitrous oxide." Atmospheric Chemistry and Physics Discussions 10, no. 11 (November 3, 2010): 25803–39. http://dx.doi.org/10.5194/acpd-10-25803-2010.
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Abstract. Seasonal cycles in the mixing ratios of tropospheric nitrous oxide (N2O) are derived by detrending long-term measurements made at sites across four global surface monitoring networks. These cycles are examined for physical and biogeochemical signals. The detrended monthly data display large interannual variability, which at some sites challenges the concept of a "mean" seasonal cycle. The interannual variability in the seasonal cycle is not always correlated among networks that share common sites. In the Northern Hemisphere, correlations between detrended N2O seasonal minima and polar winter lower stratospheric temperature provide compelling evidence for a stratospheric influence, which varies in strength from year to year and can explain much of the interannual variability in the surface seasonal cycle. Even at sites where a strong, competing, regional N2O source exists, such as from coastal upwelling at Trinidad Head, California, the stratospheric influence must be understood in order to interpret the biogeochemical signal in monthly mean data. In the Southern Hemisphere, detrended surface N2O monthly means are correlated with polar lower stratospheric temperature in months preceding the N2O minimum, suggesting a coherent stratospheric influence in that hemisphere as well. A decomposition of the N2O seasonal cycle in the extratropical Southern Hemisphere suggests that ventilation of deep ocean water (microbially enriched in N2O) and the stratospheric influx make similar contributions in phasing, and may be difficult to disentangle. In addition, there is a thermal signal in N2O due to seasonal ingassing and outgassing of cooling and warming surface waters that is out of phase and thus competes with the stratospheric and ventilation signals. All the seasonal signals discussed above are subtle and are generally better quantified in high-frequency in situ data than in data from weekly flask samples, especially in the Northern Hemisphere. The importance of abiotic influences (thermal, stratospheric influx, and tropospheric transport) on N2O seasonal cycles suggests that, at many sites, surface N2O mixing ratio data by themselves are unlikely to provide information about seasonality in surface sources (e.g., for atmospheric inversions), but may be more powerful if combined with complementary data such as CFC-12 mixing ratios or N2O isotopes.
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Ouattara, F., C. Amory-Mazaudier, R. Fleury, P. Lassudrie Duchesne, P. Vila, and M. Petitdidier. "West African equatorial ionospheric parameters climatology based on Ouagadougou ionosonde station data from June 1966 to February 1998." Annales Geophysicae 27, no. 6 (June 23, 2009): 2503–14. http://dx.doi.org/10.5194/angeo-27-2503-2009.
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Abstract. This study is the first which gives the climatology of West African equatorial ionosphere by using Ouagadougou station through three solar cycles. It has permitted to show the complete morphology of ionosphere parameters by analyzing yearly variation, solar cycle and geomagnetic activity, seasonal evolution and diurnal development. This work shows that almost all ionospheric parameters have 11-year solar cycle evolution. Seasonal variation shows that only foF2 exhibits annual, winter and semiannual anomaly. foF2 seasonal variation has permitted us to identify and characterize solar events effects on F2 layer in this area. In fact (1) during quiet geomagnetic condition foF2 presents winter and semiannual anomalies asymmetric peaks in March/April and October. (2) The absence of winter anomaly and the presence of equinoctial peaks are the most visible effects of fluctuating activity in foF2 seasonal time profiles. (3) Solar wind shock activity does not modify the profile of foF2 but increases ionization. (4) The absence of asymmetry peaks, the location of the peaks in March and October and the increase of ionization characterize recurrent storm activity. F1 layers shows increasing trend from cycle 20 to cycle 21. Moreover, E layer parameters seasonal variations exhibit complex structure. It seems impossible to detect fluctuating activity effect in E layer parameters seasonal variations but shock activity and wind stream activity act to decrease E layer ionization. It can be seen from Es layer parameters seasonal variations that wind stream activity effect is fairly independent of solar cycle. E and Es layers critical frequencies and virtual heights diurnal variations let us see the effects of the greenhouse gases in these layers.
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Guimarães, Murilo, Decio T. Correa, Marília Palumbo Gaiarsa, and Marc Kéry. "Full-annual demography and seasonal cycles in a resident vertebrate." PeerJ 8 (February 25, 2020): e8658. http://dx.doi.org/10.7717/peerj.8658.
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Wildlife demography is typically studied at a single point in time within a year when species, often during the reproductive season, are more active and therefore easier to find. However, this provides only a low-resolution glimpse into demographic temporal patterns over time and may hamper a more complete understanding of the population dynamics of a species over the full annual cycle. The full annual cycle is often influenced by environmental seasonality, which induces a cyclic behavior in many species. However, cycles have rarely been explicitly included in models for demographic parameters, and most information on full annual cycle demography is restricted to migratory species. Here we used a high-resolution capture-recapture study of a resident tropical lizard to assess the full intra-annual demography and within-year periodicity in survival, temporary emigration and recapture probabilities. We found important variation over the annual cycle and up to 92% of the total monthly variation explained by cycles. Fine-scale demographic studies and assessments on the importance of cycles within parameters may be a powerful way to achieve a better understanding of population persistence over time.
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Swedan, Nabil H. "Parameterization of energy cycles between the hemispheres." Science Progress 103, no. 2 (April 2020): 003685042092277. http://dx.doi.org/10.1177/0036850420922773.
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Seasonal variations in the temperatures of the hemispheres induce seasonal energy cycles between the hemispheres that drive tropical cyclones. Because the northern hemisphere has warmed more than the southern hemisphere, climate energy cycles develop between the hemispheres as well. The seasonal and climate energy cycles appear to interact among themselves, and tropical cyclone counts are affected by these interactions. Furthermore, the total number of tropical cyclones appears to have an increasing trend. The annual energy of tropical cyclones is nearly 1.46 × 1022 J yr−1, and climate cycle energy is between 4.0 and 6.6 × 1021 J per cycle. The magnitude of the climate energy cycles is thus large enough to alter the energy and frequency of the tropical cyclones. Given that the climate is changing, the energy and frequency of tropical cyclones may be changing as well. The subject is broad and this work is limited to parameterization of the physics of energy oscillations between the hemispheres, demonstrating the existence of climate energy cycles, and revealing interactions between climate and seasonal energy cycles. Also, this parameterization may assist researchers in obtaining more and coordinated data relative to these cycles.
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Bowman, Henry, Steven Turnock, Susanne E. Bauer, Kostas Tsigaridis, Makoto Deushi, Naga Oshima, Fiona M. O'Connor, et al. "Changes in anthropogenic precursor emissions drive shifts in the ozone seasonal cycle throughout the northern midlatitude troposphere." Atmospheric Chemistry and Physics 22, no. 5 (March 16, 2022): 3507–24. http://dx.doi.org/10.5194/acp-22-3507-2022.
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Abstract. Simulations by six Coupled Model Intercomparison Project Phase 6 (CMIP6) Earth system models indicate that the seasonal cycle of baseline tropospheric ozone at northern midlatitudes has been shifting since the mid-20th century. Beginning in ∼ 1940, the magnitude of the seasonal cycle increased by ∼10 ppb (measured from seasonal minimum to maximum), and the seasonal maximum shifted to later in the year by about 3 weeks. This shift maximized in the mid-1980s, followed by a reversal – the seasonal cycle decreased in amplitude and the maximum shifted back to earlier in the year. Similar changes are seen in measurements collected from the 1970s to the present. The timing of the seasonal cycle changes is generally concurrent with the rise and fall of anthropogenic emissions that followed industrialization and the subsequent implementation of air quality emission controls. A quantitative comparison of the temporal changes in the ozone seasonal cycle at sites in both Europe and North America with the temporal changes in ozone precursor emissions across the northern midlatitudes found a high degree of similarity between these two temporal patterns. We hypothesize that changing precursor emissions are responsible for the shift in the ozone seasonal cycle; this is supported by the absence of such seasonal shifts in southern midlatitudes where anthropogenic emissions are much smaller. We also suggest a mechanism by which changing emissions drive the changing seasonal cycle: increasing emissions of NOx allow summertime photochemical production of ozone to become more important than ozone transported from the stratosphere, and increasing volatile organic compounds (VOCs) lead to progressively greater photochemical ozone production in the summer months, thereby increasing the amplitude of the seasonal ozone cycle. Decreasing emissions of both precursor classes then reverse these changes. The quantitative parameter values that characterize the seasonal shifts provide useful benchmarks for evaluating model simulations, both against observations and between models.
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Foltz, Gregory R., Claudia Schmid, and Rick Lumpkin. "Seasonal Cycle of the Mixed Layer Heat Budget in the Northeastern Tropical Atlantic Ocean." Journal of Climate 26, no. 20 (October 4, 2013): 8169–88. http://dx.doi.org/10.1175/jcli-d-13-00037.1.
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Abstract The seasonal cycle of the mixed layer heat budget in the northeastern tropical Atlantic (0°–25°N, 18°–28°W) is quantified using in situ and satellite measurements together with atmospheric reanalysis products. This region is characterized by pronounced latitudinal movements of the intertropical convergence zone (ITCZ) and strong meridional variations of the terms in the heat budget. Three distinct regimes within the northeastern tropical Atlantic are identified. The trade wind region (15°–25°N) experiences a strong annual cycle of mixed layer heat content that is driven by approximately out-of-phase annual cycles of surface shortwave radiation (SWR), which peaks in boreal summer, and evaporative cooling, which reaches a minimum in boreal summer. The surface heat-flux-induced changes in the mixed layer heat content are damped by a strong annual cycle of cooling from vertical turbulent mixing, estimated from the residual in the heat balance. In the ITCZ core region (3°–8°N) a weak seasonal cycle of mixed layer heat content is driven by a semiannual cycle of SWR and damped by evaporative cooling and vertical turbulent mixing. On the equator the seasonal cycle of mixed layer heat content is balanced by an annual cycle of SWR that reaches a maximum in October and a semiannual cycle of turbulent mixing that cools the mixed layer most strongly during May–July and November. These results emphasize the importance of the surface heat flux and vertical turbulent mixing for the seasonal cycle of mixed layer heat content in the northeastern tropical Atlantic.
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Kangasaho, Vilma, Aki Tsuruta, Leif Backman, Pyry Mäkinen, Sander Houweling, Arjo Segers, Maarten Krol, et al. "The Role of Emission Sources and Atmospheric Sink in the Seasonal Cycle of CH4 and δ13-CH4: Analysis Based on the Atmospheric Chemistry Transport Model TM5." Atmosphere 13, no. 6 (May 30, 2022): 888. http://dx.doi.org/10.3390/atmos13060888.
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This study investigates the contribution of different CH4 sources to the seasonal cycle of δ13C during 2000–2012 by using the TM5 atmospheric transport model, including spatially varying information on isotopic signatures. The TM5 model is able to produce the background seasonality of δ13C, but the discrepancies compared to the observations arise from incomplete representation of the emissions and their source-specific signatures. Seasonal cycles of δ13C are found to be an inverse of CH4 cycles in general, but the anti-correlations between CH4 and δ13C are imperfect and experience a large variation (p=−0.35 to −0.91) north of 30° S. We found that wetland emissions are an important driver in the δ13C seasonal cycle in the Northern Hemisphere and Tropics, and in the Southern Hemisphere Tropics, emissions from fires contribute to the enrichment of δ13C in July–October. The comparisons to the observations from 18 stations globally showed that the seasonal cycle of EFMM emissions in the EDGAR v5.0 inventory is more realistic than in v4.3.2. At northern stations (north of 55° N), modeled δ13C amplitudes are generally smaller by 12–68%, mainly because the model could not reproduce the strong depletion in autumn. This indicates that the CH4 emission magnitude and seasonal cycle of wetlands may need to be revised. In addition, results from stations in northern latitudes (19–40° N) indicate that the proportion of biogenic to fossil-based emissions may need to be revised, such that a larger portion of fossil-based emissions is needed during summer.
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Burls, N. J., C. J. C. Reason, P. Penven, and S. G. Philander. "Energetics of the Tropical Atlantic Zonal Mode." Journal of Climate 25, no. 21 (November 2012): 7442–66. http://dx.doi.org/10.1175/jcli-d-11-00602.1.
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Sea surface temperature in the central-eastern equatorial Atlantic has a seasonal cycle far bigger than that of the Pacific, but interannual anomalies smaller than those of the Pacific. Given the amplitude of seasonal SST variability, one wonders whether the seasonal cycle in the Atlantic is so dominant that it is able to strongly influence the evolution of its interannual variability. In this study, interannual upper-ocean variability within the tropical Atlantic is viewed from an energetics perspective, and the role of ocean dynamics, in particular the role of ocean memory, within zonal mode events is investigated. Unlike in the Pacific where seasonal and interannual variability involve distinctly different processes, the results suggest that the latter is a modulation of the former in the Atlantic, whose seasonal cycle has similarities with El Niño and La Niña in the Pacific. The ocean memory mechanism associated with the zonal mode appears to operate on much shorter time scales than that associated with the El Niño–Southern Oscillation, largely being associated with interannual modulations of a seasonally active delayed negative feedback response. Differences between the El Niño–Southern Oscillation and the zonal mode can then be accounted for in terms of these distinctions. Anomalous wind power over the tropical Atlantic is shown to be a potential predictor for zonal mode events. However, because zonal mode events are due to a modulation of seasonally active coupled processes, and not independent processes operating on interannual time scales as seen in the Pacific, the lead time of this potential predictability is limited.
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Asher, G. W. "Impacts of nutrition on reproduction in female red deer: phenotypic flexibility within a photoperiod-mediated seasonal cycle." Animal Production Science 60, no. 10 (2020): 1238. http://dx.doi.org/10.1071/an19040.
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Red deer (Cervus elaphus) are widely distributed throughout cold northern temperate latitudes, where they have evolved to cope within highly seasonal continental environments. Naturalisation of red deer to the more moderate seasonal (but variable climatic) environment of New Zealand has been spectacularly successful, and they are widely farmed in the country’s pastoral environment for venison and antlers. The species is genetically programmed to exhibit photoperiodic control of voluntary feed intake, growth and reproduction, ensuring that energy demands are aligned with seasonally available resources and offspring are born in summer when climate is favourable for survival. However, despite genetic control of their endogenous seasonal cycles, there appears to be a strong ability for environmental factors such as nutrition to generate large phenotypic variation of seasonal traits. This may have contributed to their successful naturalisation to a wider range of seasonal environments than would be expected within their ancestral range. While precise timing of conception and duration of gestation length are the two fundamental mechanisms by which the strict seasonality of birth is maintained in seasonally breeding mammals, red deer exhibit considerable variation in both these traits. The present paper examines the outcomes of recent studies on farmed red deer on the impacts of lactation on conception date, the influence of nutrition during pregnancy on gestation length, and early life growth effects on the onset of female puberty. These studies have collectively demonstrated that while red deer are assumed to be under fairly rigorous genetic control of seasonality traits, they have a repertoire of phenotypic variation at various points of the reproductive cycle that may potentially allow a degree of adaptation to climatic variation that influences annual feed supply. This may explain the success of red deer in colonising a range of new environments that differ seasonally from their ancestral environment.
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Wang, Xun, Andrew E. Dessler, Mark R. Schoeberl, Wandi Yu, and Tao Wang. "Impact of convectively lofted ice on the seasonal cycle of water vapor in the tropical tropopause layer." Atmospheric Chemistry and Physics 19, no. 23 (December 3, 2019): 14621–36. http://dx.doi.org/10.5194/acp-19-14621-2019.
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Abstract. We use a forward Lagrangian trajectory model to diagnose mechanisms that produce the water vapor seasonal cycle observed by the Microwave Limb Sounder (MLS) and reproduced by the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM) in the tropical tropopause layer (TTL). We confirm in both the MLS and GEOSCCM that the seasonal cycle of water vapor entering the stratosphere is primarily determined by the seasonal cycle of TTL temperatures. However, we find that the seasonal cycle of temperature predicts a smaller seasonal cycle of TTL water vapor between 10 and 40∘ N than observed by MLS or simulated by the GEOSCCM. Our analysis of the GEOSCCM shows that including evaporation of convective ice in the trajectory model increases both the simulated maximum value of the 100 hPa 10–40∘ N water vapor seasonal cycle and the seasonal-cycle amplitude. We conclude that the moistening effect from convective ice evaporation in the TTL plays a key role in regulating and maintaining the seasonal cycle of water vapor in the TTL. Most of the convective moistening in the 10–40∘ N range comes from convective ice evaporation occurring at the same latitudes. A small contribution to the moistening comes from convective ice evaporation occurring between 10∘ S and 10∘ N. Within the 10–40∘ N band, the Asian monsoon region is the most important region for convective moistening by ice evaporation during boreal summer and autumn.
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Liu, Fukai, Jian Lu, Yiyong Luo, Yi Huang, and Fengfei Song. "On the Oceanic Origin for the Enhanced Seasonal Cycle of SST in the Midlatitudes under Global Warming." Journal of Climate 33, no. 19 (October 1, 2020): 8401–13. http://dx.doi.org/10.1175/jcli-d-20-0114.1.
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AbstractClimate models project an enhancement in SST seasonal cycle over the midlatitude oceans under global warming. The underlying mechanisms are investigated using a set of partially coupled experiments, in which the contribution from direct CO2 effects (i.e., the response in the absence of wind change) and wind feedbacks can be isolated from each other. Results indicate that both the direct CO2 and wind effects contribute to the enhancement in the SST seasonal cycle, with the former (latter) being more important in the Northern Hemisphere (Southern Hemisphere). Further decomposition of the wind effect into the wind stress feedback and wind speed feedback reveals the importance of the wind stress–driven ocean response in the change of SST seasonal cycle, a result in contrast to a previous study that ascribed the midlatitude SST seasonal cycle change to the thermodynamic wind speed feedback. The direct CO2 effect regulates the SST seasonal cycle through the warming-induced shoaling in the annual mean mixed layer depth (MLD) as well as the MLD difference between winter and summer. Moreover, the surface wind seasonal cycle changes due solely to the direct CO2 effect are found to bear a great resemblance to the full wind response, suggesting that the root cause for the enhancement of the midlatitude SST seasonal cycle resides in the direct CO2 effect. This notion is further supported by an ocean-alone experiment that reproduces the SST seasonal cycle enhancement under a spatially and temporally homogeneous surface thermal forcing.
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Boersma, K. F., D. J. Jacob, M. Trainic, Y. Rudich, I. DeSmedt, R. Dirksen, and H. J. Eskes. "Validation of urban NO<sub>2</sub> concentrations and their diurnal and seasonal variations observed from space (SCIAMACHY and OMI sensors) using in situ measurements in Israeli cities." Atmospheric Chemistry and Physics Discussions 9, no. 1 (February 10, 2009): 4301–33. http://dx.doi.org/10.5194/acpd-9-4301-2009.
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Abstract. We compare a full-year (2006) record of surface air NO2 concentrations measured in Israeli cities to coinciding retrievals of tropospheric NO2 columns from satellite sensors (SCIAMACHY aboard ENVISAT and OMI aboard Aura). This provides a large statistical data set for validation of NO2 satellite measurements in urban air, where validation is difficult yet crucial for using these measurements to infer NOx emissions by inverse modeling. Assuming that NO2 is well-mixed throughout the boundary layer (BL), and using observed average seasonal boundary layer heights, near-surface NO2 concentrations are converted into BL NO2 columns. The agreement between OMI and (13:45) BL NO2 columns (slope=0.93, n=542), and the comparable results at 10:00 h for SCIAMACHY, allow a validation of the seasonal, weekly, and diurnal cycles in satellite-derived NO2. OMI and BL NO2 columns show consistent seasonal cycles (winter NO2 1.6–2.7× higher than summer). BL and coinciding OMI columns both show a strong weekly cycle with 45–50% smaller NO2 columns on Saturday relative to the weekday mean, reflecting the reduced weekend activity, and validating the weekly cycle observed from space. The diurnal difference between SCIAMACHY (10:00) and OMI (13:45) NO2 is maximum in summer when SCIAMACHY is up to 40% higher than OMI, and minimum in winter when OMI slightly exceeds SCIAMACHY. A similar seasonal variation in the diurnal difference is found in the source region of Cairo. The surface measurements in Israel cities confirm this seasonal variation in the diurnal cycle. Using simulations from a global 3-D chemical transport model (GEOS-Chem), we show that this seasonal cycle can be explained by a much stronger photochemical loss of NO2 in summer than in winter.
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Boersma, K. F., D. J. Jacob, M. Trainic, Y. Rudich, I. DeSmedt, R. Dirksen, and H. J. Eskes. "Validation of urban NO<sub>2</sub> concentrations and their diurnal and seasonal variations observed from the SCIAMACHY and OMI sensors using in situ surface measurements in Israeli cities." Atmospheric Chemistry and Physics 9, no. 12 (June 15, 2009): 3867–79. http://dx.doi.org/10.5194/acp-9-3867-2009.
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Abstract. We compare a full-year (2006) record of surface air NO2 concentrations measured in Israeli cities to coinciding retrievals of tropospheric NO2 columns from satellite sensors (SCIAMACHY aboard ENVISAT and OMI aboard Aura). This provides a large statistical data set for validation of NO2 satellite measurements in urban air, where validation is difficult yet crucial for using these measurements to infer NOx emissions by inverse modeling. Assuming that NO2 is well-mixed throughout the boundary layer (BL), and using observed average seasonal boundary layer heights, near-surface NO2 concentrations are converted into BL NO2 columns. The agreement between OMI and (13:45) BL NO2 columns (slope=0.93, n=542), and the comparable results at 10:00 h for SCIAMACHY, allow a validation of the seasonal, weekly, and diurnal cycles in satellite-derived NO2. OMI and BL NO2 columns show consistent seasonal cycles (winter NO2 1.6–2.7× higher than summer). BL and coinciding OMI columns both show a strong weekly cycle with 45–50% smaller NO2 columns on Saturday relative to the weekday mean, reflecting the reduced weekend activity, and validating the weekly cycle observed from space. The diurnal difference between SCIAMACHY (10:00) and OMI (13:45) NO2 is maximum in summer when SCIAMACHY is up to 40% higher than OMI, and minimum in winter when OMI slightly exceeds SCIAMACHY. A similar seasonal variation in the diurnal difference is found in the source region of Cairo. The surface measurements in Israel cities confirm this seasonal variation in the diurnal cycle. Using simulations from a global 3-D chemical transport model (GEOS-Chem), we show that this seasonal cycle can be explained by a much stronger photochemical loss of NO2 in summer than in winter.