排序方式： 共有10条查询结果，搜索用时 15 毫秒
1
1.
研究了数值天气预报模式中次阿格湍流垂直扩散过程的参数化问题。以Ｂｏｕｇｅａｕｌｔ和Ｌａｃａｒｒｅｒｅ（１９８９）的参数化方案为基础，改进了处理湍流混合长的方法，使湍流混合长和热力混合长分别依赖于基本气流的静力稳定度和风场切变。新方案的基本思路是把ＶｏｎＫａｒｍａｎ（１９３０）提出的动力（风场切变）湍流扰动假设与ＢＬ－８９方案提出的热力（静力稳定度）湍流扰动假设结合在一起，强调了大气的热力结构、动力结构和湍流动能对湍流混合过程的共同影响。新方案和ＢＬ－８９方案的二维对比数值试验结果表明，在大气处于静力较稳定而风场切变明显条件下的湍流扰动表现能力方面，新方案比原方案有明显的改进。 相似文献
2.
Résumé Dans le cadre des multifractals universels, il est possible de caractériser la variabilité spatio-temporelle de la pluie sur une grande gamme d’échelle à l'aide de trois paramètres invariants d’échelles. Dans cette étude, nous avons estimé ces paramètres multifractals sur des simulations numériques effectuées avec le modèle méso-échelle Méso-NH, développé par Météo-France et le Laboratoire d'Aérologie (Univ. P. Sabatier, Toulouse, France), et des images radar composites, couvrant le même événement pluvieux, à savoir un orage particulièrement violent, dit de type Cévenol, ayant eu lieu sur la partie sud de la France du 5 au 9 Septembre 2005. La comparaison des résultats montre que les deux types de données présentent des domaines d'invariance d’échelle relativement similaires, et dont les propriétés sont en accord avec les modèles de précipitation spatio-temporels unifiés et scalants les plus simples. Néanmoins l’évaluation de leurs exposants conduit à des valeurs parfois fortement différentes. Citation Gires, A., Tchiguirinskaia, I., Schertzer, D. & Lovejoy, S. (2011) Analyses multifractales et spatio-temporelles des précipitations du modèle Méso-NH et des données radar. Hydrol. Sci. J. 56(3), 380–396. 相似文献
3.
4.
Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean 总被引：1，自引：1，他引：1
5.
This paper presents some statistical evaluations of the surface energy and soil water balance fluxes, for a prairie-type canopy, using the Earth model with a double-reservoir system for the management of the soil water reserve and the regulation of actual evapotranspiration. The mean values of these fluxes are estimated from energy and water balance simulations done on a 30-year climatic reference period (1951-1980). From values of these fluxes calculated for each meteorological synoptic station, mappings of net radiation, actual evapotranspiration, drainage and conduction fluxes have been made over French territory. Lastly, a few conclusions pertaining to the spatial variability of fluxes and to the partition of rainfall between run-off and drainage on the one hand and replenishment of the soil water reserve on the other hand are drawn from these preliminary results. 相似文献
6.
Summary ?The interannual variability of broad-scale Asian summer monsoon was studied using a general circulation model (GCM) and NCEP
(National Center for Environmental Prediction) data set during 1979–95. In the GCM experiment, the main emphasis was given
to isolate the individual role of surface boundary conditions on the existence of winter-spring time circulation anomalies
associated with the interannual variability of Asian summer monsoon.
In order to understand the role of sea-surface temperatures (SSTs) alone on the existence of precursory signals, we have conducted
17 years numerical integration with a GCM forced with the real-time monthly averaged SSTs of 1979 to 1995. In this experiment,
among the many surface boundary conditions only SSTs are varying interannually. The composite circulation anomalies simulated
by the GCM have good resemblance with the NCEP circulation anomalies over subtropical Asia. This suggests that the root cause
of the existence of winter-spring time circulation anomalies associated with the interannual variability of Asian summer monsoon
is the interannual variability of SST.
Empirical Orthogonal Functions (EOFs) of 200-mb winds and OLR were constructed to study the dynamic coupling between SST anomalies
and winter-spring time circulation anomalies. It is found that the convective heating anomalies associated with SST anomalies
and stationary eddies undergo systematic and coherent interannual variations prior to summer season. We have identified Matsuno-Gill
type mode in the velocity potential and stream function fields. This suggests the existence of dynamic links between the SST
anomalies and the precursory signals of Asian summer monsoon.
Received June 9, 1999/Revised April 7, 2000 相似文献
7.
8.
The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China,
acquired through a CE318 sunphotometer of the ground-based Aerosol Robotic Network (AERONET), are analyzed. The
seasonal variations in the aerosol optical properties are examined. The effect of meteorological elements
(pressure, temperature, water vapor pressure, relative humidity and wind speed) on the aerosol optical properties
is also studied. Then, the sources and optical properties under two different cases, a dust event and a pollution
event, are compared. The results show that the high aerosol optical depth (AOD) found in Yulin was mostly
attributed to the occurrence of dust events in spring from the Mu Us desert and deserts of West China and
Mongolia, as well as the impacts of anthropogenic pollutant particles from the middle part of China in the
other seasons. The seasonal variation and the probability distribution of the radiative forcing and the
radiative forcing efficiency at the surface and the top of the atmosphere are analyzed and regressed using
the linear and Gaussian regression methods. 相似文献
9.
F. Kucharski A. A. Scaife J. H. Yoo C. K. Folland J. Kinter J. Knight D. Fereday A. M. Fischer E. K. Jin J. Kröger N.-C. Lau T. Nakaegawa M. J. Nath P. Pegion E. Rozanov S. Schubert P. V. Sporyshev J. Syktus A. Voldoire J. H. Yoon N. Zeng T. Zhou 《Climate Dynamics》2009,33(5):615-627
The ability of atmospheric general circulation models (AGCMs), that are forced with observed sea surface temperatures (SSTs),
to simulate the Indian monsoon rainfall (IMR) variability on interannual to decadal timescales is analyzed in a multimodel
intercomparison. The multimodel ensemble has been performed within the CLIVAR International “Climate of the 20th Century”
(C20C) Project. This paper is part of a C20C intercomparison of key climate time series. Whereas on the interannual timescale
there is modest skill in reproducing the observed IMR variability, on decadal timescale the skill is much larger. It is shown
that the decadal IMR variability is largely forced, most likely by tropical sea surface temperatures (SSTs), but as well by
extratropical and especially Atlantic Multidecadal Oscillation (AMO) related SSTs. In particular there has been a decrease
from the late 1950s to the 1990s that corresponds to a general warming of tropical SSTs. Using a selection of control integrations
from the World Climate Research Programme’s (WCRP’s) Coupled Model Intercomparison Project phase 3 (CMIP3), it is shown that
the increase of greenhouse gases (GHG) in the twentieth century has not significantly contributed to the observed decadal
IMR variability. 相似文献
10.
The response of the Weddell Sea and Antarctic Peninsula to anthropogenic forcing simulated by a global climate model is analyzed. The model, despite its low resolution, is able to capture several aspects of the observed regional pattern of climate change. A strong warming and depletion of the sea ice cover in the western Weddell Sea contrasts with a slight cooling and a sea-ice extension in the eastern Weddell Sea. This simulated long-term climate change is modulated by interdecadal variability but also affected by some abrupt regional changes in the oceanic mixed layer depth. Between 1960 and 2030 a reorganization of the deep convection activity in the Weddell Sea sustains the opposition between the eastern and western Weddell Sea. The deep convection collapses in the western Weddell Sea in the 2030s. The sea ice retreat trend is then followed by an increase of the sea ice cover in the western Weddell Sea. In the eastern Weddell Sea another abrupt collapse of the deep convection activity occurs around 2080. This event is followed by a rapid cooling and sea ice extension during the next 20 years. Most of the surface changes are associated with large-scale atmospheric circulation changes that project on the dominant mode of natural variability but also with oceanic convection and circulation changes. 相似文献
1