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Potential links between the Arctic sea-ice concentration anomalies and extreme precipitation in China are explored. Associations behind these links can be explained by physical interpretations aided by... 相似文献
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Mauro Dall’Amico Peter A. Stott Adam A. Scaife Lesley J. Gray Karen H. Rosenlof Alexey Yu. Karpechko 《Climate Dynamics》2010,34(2-3):399-417
An improved stratospheric representation has been included in simulations with the Hadley Centre HadGEM1 coupled ocean atmosphere model with natural and anthropogenic forcings for the period 1979–2003. An improved stratospheric ozone dataset is employed that includes natural variations in ozone as well as the usual anthropogenic trends. In addition, in a second set of simulations the quasi biennial oscillation (QBO) of stratospheric equatorial zonal wind is also imposed using a relaxation towards ERA-40 zonal wind values. The resulting impact on tropospheric variability and trends is described. We show that the modelled cooling rate at the tropopause is enhanced by the improved ozone dataset and this improvement is even more marked when the QBO is also included. The same applies to warming trends in the upper tropical troposphere which are slightly reduced. Our stratospheric improvements produce a significant increase of internal variability but no change in the positive trend of annual mean global mean near-surface temperature. Warming rates are increased significantly over a large portion of the Arctic Ocean. The improved stratospheric representation, especially the QBO relaxation, causes a substantial reduction in near-surface temperature and precipitation response to the El Chichón eruption, especially in the tropical region. The winter increase in the phase of the northern annular mode observed in the aftermath of the two major recent volcanic eruptions is partly captured, especially after the El Chichón eruption. The positive trend in the southern annular mode (SAM) is increased and becomes statistically significant which demonstrates that the observed increase in the SAM is largely subject to internal variability in the stratosphere. The possible inclusion in simulations for future assessments of full ozone chemistry and a gravity wave scheme to internally generate a QBO is discussed. 相似文献
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The correspondence between multiyear mean values of annual transpiration values derived with the Penman-Monteith methods using
the coefficient of transpiration efficiency is demonstrated. It is suggested to take into account climate peculiarities in
the region when estimating the transpiration with the Penman-Monteith method. In the mid-taiga sub-zone that is characterized
by high moisture content, the stomatal resistance (conductance) of the leaf apparatus, when calculating the diurnal transpiration,
can be taken as constant, independent of the meteorological conditions. 相似文献
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The evaporation from forest area is shown to depend to a large degree on the growth conditions and productivity of forest stand; under the climatic conditions of the Eastern Fennoscandia, the variations in the productivity of forest stand of a particular forest type are mainly governed by the temperature. It is found that at the likely rise of the mean annual air temperature by 1 and 2°C, the average productivity of coniferous forest would increase by 0.3–0.7 (depending on the tree species and physiographic subzone) and 0.6–1.1 of the forest stand quality class, respectively; the increase in the annual evapotranspiration from a relatively large forest drainage basin could average 20–25 mm at a 2°C-temperature rise. 相似文献
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The leading mode of southern hemisphere (SH) climatic variability, the southern annular mode (SAM), has recently seen a shift towards its positive phase due to stratospheric ozone depletion and increasing greenhouse gas (GHG) concentrations. Here we examine how sensitive the SAM (defined as the leading empirical orthogonal function of SH sea level pressure anomalies) is to future GHG concentrations. We determine its likely evolution for three intergovernmental panel on climate change (IPCC) special report on emission scenarios (SRES) for austral summer and winter, using a multi-model ensemble of IPCC fourth assessment report models which resolve stratospheric ozone recovery. During the period of summer ozone recovery (2000–2050), the SAM index exhibits weakly negative, statistically insignificant trends due to stratospheric ozone recovery which offsets the positive forcing imposed by increasing GHG concentrations. Thereafter, positive SAM index trends occur with magnitudes that show sensitivity to the SRES scenario utilised, and thus future GHG emissions. Trends are determined to be strongest for SRES A2, followed by A1B and B1, respectively. The winter SAM maintains a similar dependency upon GHG as summer, but over the entire twenty-first century and to a greater extent. We also examine the influence of ozone recovery by comparing results to models that exclude stratospheric ozone recovery. Projections are shown to be statistically different from the aforementioned results, highlighting the importance of ozone recovery in governing SAM-evolution. We therefore demonstrate that the future SAM will depend both upon GHG emissions and stratospheric ozone recovery. 相似文献
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A. N. Luk’yanov A. Yu. Karpechko V. A. Yushkov L. I. Korshunov S. M. Khaikin A. V. Gan’shin E. Kyro R. Kivi M. Maturilli H. Voemel 《Izvestiya Atmospheric and Oceanic Physics》2009,45(3):294-301
Processes of mass exchange through the tropopause at extratropical latitudes are studied. For this purpose, balloon data on ozone and water vapor obtained during the LAUTLOS field campaign were analyzed and a trajectory model was used to analyze the origin of air masses and to calculate fluxes through the tropopause. The results of observations and trajectory modeling showed that tropospheric air masses penetrated into the stratosphere by no more than ～2.5 km above the tropopause level during the campaign. Both tropospheric and stratospheric particles are present in this mixing layer. Backward trajectories showed that, at the anticyclone boundary, tropospheric air penetrates into the stratosphere in the form of fine fibrous structures (filaments). The fluxes through the tropopause were also quantitatively estimated by the Wei method with the use of forward and backward trajectories. The spatial structure of the fluxes through the tropopause coincides with the regions of the tropopause inclination and its folds. The absolute values of the fluxes calculated with the use of the Wei method decrease, depending on the length of trajectories at the expense of the filtering-out of a shallow reversible exchange. It is shown that the exchange depth can be controlled by both vertical fluxes in the troposphere and changes in the level of the tropopause itself. The use of isentropic and three-dimensional trajectories made it possible to estimate the contribution of nonadiabatic processes to the stratosphere-troposphere exchange. 相似文献
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A. V. Litvinenko N. N. Filatov M. S. Bogdanova V. A. Karpechko I. A. Litvinova Yu. A. Salo 《Water Resources》2014,41(4):454-463
Stages of anthropogenic transformation of Vygozero are demonstrated. Hydrographic and hydrologic characteristics are given to the Vogozersko-Ondskoe Reservoir and its drainage area at different stages of its development. The current state and dynamics of the economic use of the reservoir and its watershed are estimated with the use of GIS-technologies (databases and GIS “Water Users of the Republic of Karelia”). 相似文献
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Data from long-term hydrometeorological observations are taken on drainage areas in southern Karelia. The role of the factors that govern the transformations of the water balance of bogs and swampy forests in the process of their development is established. The anthropogenic components of runoff dynamics from drained fields are calculated. 相似文献
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