Recent Progress in the Impact of the Tibetan Plateau on Climate in China

Studies of the impacts of the Tibetan Plateau （TP） on climate in China in the last four years are reviewed. It is reported that temperature and precipitation over the TP have increased during recent decades. From satellite data analysis, it is demonstrated that most of the precipitation over the TP is from deep convection clouds. Moreover, the huge TP mechanical forcing and extraordinary elevated thermal forcing impose remarkable impacts upon local circulation and global climate. In winter and spring, stream flow is deflected by a large obstacle and appears as an asymmetric dipole, making East Asia much colder than mid Asia in winter and forming persistent rainfall in late winter and early spring over South China. In late spring, TP heating contributes to the establishment and intensification of the South Asian high and the abrupt seasonal transition of the surrounding circulations. In summer, TP heating in conjunction with the TP air pump cause the deviating stream field to resemble a cyclonic spiral, converging towards and rising over the TP. Therefore, the prominent Asian monsoon climate over East Asia and the dry climate over mid Asia in summer are forced by both TP local forcing and Eurasian continental forcing.
Due to the longer memory of snow and soil moisture, the TP thermal status both in summer and in late winter and spring can influence the variation of Eastern Asian summer rainfall. A combined index using both snow cover over the TP and the ENSO index in winter shows a better seasonal forecast.
On the other hand, strong sensible heating over the Tibetan Plateau in spring contributes significantly to anchor the earliest Asian monsoon being over the eastern Bay of Bengal （BOB） and the western Indochina peninsula. Qualitative prediction of the BOB monsoon onset was attempted by using the sign of meridional temperature gradient in March in the upper troposphere, or at 400 hPa over the TP. It is also demonstrated by a numerical experiment and theoretical study that the heating over the TP lea     

A Numerical Experiment of Mesolow on the Eastern Side of the Taihang Mountains

A numerical experiment on the formation and decay process of a mesolow on the plain east to the Taihang Mountains has been conducted. The dynamical effect of the special topography of the Taihang Mountains and the Yanshan Mountains on the formation of the mesolow is very important. Namely, the difference of the heating between the Taihang Mountains and the North China plain plays an important role in the formation and decay of the mesolow.     

The Role of Topography and Diabatic Heating in the Formation of Dipole Blocking in the Atmosphere

In this paper, the nonlinear stationary waves forced by topography and diabatic heating are investigated. It is pointed out that (1) the nonlinear interaction of different stationary waves forced only by topography might form dipole blocking in the atmosphere, this might explain the dipole blocking appeared in the Pacific and Atlantic regions; (2) the dipole blocking could not be caused by the nonlinear interaction of the different stationary waves forced by the diabatic heating alone; (3) the nonlinear interaction of the diffferent stationary waves forced by both topography and diabatic heating could initiate dipole blocking in the atmosphere. In winter, the dipole blocking mainly occurs in the west regions of the Pacific and the Atlantic, and the heat source over the western part of the two oceans is advantageous to the formation of dipole blocking in the west of two oceans. However, in summer, the dipole blocking could be formed in the east part of the two oceans, and the heat source over the eastern     

The Persistent Heavy Rainfall over Southern China in June 2010：Evolution of Synoptic Systems and the Effects of the Tibetan Plateau Heating

This study investigates influencing weather systems for and the effect of Tibetan Plateau （TP）’s surface heating on the heavy rainfall over southern China in June 2010, focusing on the four persistent heavy rainfall events during 14-24 June 2010. The ma jor weather systems include the South Asian high, midlatitude trough and ridge, western Pacific subtropical high in the middle troposphere, and shear lines and eastward-moving vortices in the lower troposphere. An ensemble of convection-permitting simulations （CTL） is carried out with the WRF model for these rainfall events, which successfully reproduce the observed evolution of precipitation and weather systems. Another ensemble of simulations （SEN） with the surface albedo over the TP and its southern slope changed artificially to one, i.e., the surface does not absorb any solar heating, otherwise it is identical to CTL, is also performed. Comparison between CTL and SEN suggests that the surface sensible heating of TP in CTL significantly affects the temperature distributions over the plateau and its surroundings, and the thermal wind adjustment consequently changes atmospheric circulations and properties of the synoptic systems, leading to intensified precipitation over southern China. Specifically, at 200 hPa, anticyclonic and cyclonic anomalies form over the western and eastern plateau, respectively, which enhances the southward cold air intrusion along the eastern TP and the divergence over southern China;at 500 hPa, the ridge over the northern plateau and the trough over eastern China are strengthened, the southwesterly flows along the northwestern side of the subtropical high are intensified, and the positive vorticity propagation from the plateau to its downstream is also enhanced significantly;at 850 hPa, the low-pressure vortices strongly develop and move eastward while the southwesterly low-level jet over southern China strengthens in CTL, leading to increased water vapor convergence and upward motion over the precipitation region.     

Impacts of SST and SST Anomalies on Low-Frequency Oscillation in the Tropical Atmosphere

Considering the multiscale character of LFO effects of SST on LFO in the tropical atmosphere （low-frequency oscillation） in the tropical atmosphere, the are discussed by using an absolute ageostrophic, baroclinic model. Here, SST effects include sea surface heating and forcing of SST anomalies （SSTAs）. Studies of the influences of sea surface heating on LFO frequency and stability show that sea surface heating can slow the speed of waves and lower their frequency when SST is comparatively low; while higher SST leads to unstable waves and less periods of LFO. Since the impact of a SSTA on ultra-long waves is more evident than that on kilometer-scale waves, long-wave approximation is used when we continue to study the effect of SSTAs. Results indicate that SSTAs can lead to a longer period of LFO, and make waves unstable. In other words, positive （negative） SSTAs can make waves decay （grow）.     

An Aridity Trend in China and Its Abrupt Feature in Association with the Global Warming

A distinct aridity trend in China in last 100 years is presented by applying a linear fitting to both the climate records and the hydrological records, which is supported by evidence of environmental changes and seems to be associated with a global warming trend during this period.The Mann Kendall Rank statistic test reveals a very interesting feature that the climate of China entered into a dry regime abruptly in about 1920's, which synchronized with the rapid warming of the global temperature at almost the same time.According to an analysis of the meridional profile of observed global zonal mean precipitation anomalies during the peak period of global wanning (1930-1940), the drought occurred in whole middle latitude zone (25°N-55°N) of the Northern Hemisphere, where the most part of China is located in. Although this pattern is in good agreement with the latitude distribution of the difference of zonal mean rates of precipitation between 4 × CO2 and 1 × CO2 simulated by climate model (Manabe and     

The Influence of ENSO on the Summer Climate Change in China and Its Mechanism

The influence of ENSO on the summer climate change in China and its mechanism from the observed data is discussed. It is discovered that in the developing stage of ENSO, the SST in the western tropical Pacific is colder in summer, the convective activities may be weak around the South China Sea and the Philippines. As a consequence, the subtropical high shifted southward. Therefore, a drought may be caused in the Indo-China peninsula and in the South China. Moreover, in midsummer the subtropical high is weak over the Yangtze River valley and Huaihe River valley, and the flood may be caused in the area from the Yangtze River valley to Huaihe River valley. On the contrary, in the decaying stage of ENSO. the convective activities may be strong around the Philippines, and the subtropical high shifted northward, a drought may be caused in the Yangtze River valley and Huaihe River valley.     

Impacts of SST and SST Anomalies on Low-Prequency Oscillation in the Tropical Atmosphere

Considering the multiscale character of LFO (low-frequency oscillation) in the tropical atmosphere, the effects of SST on LFO in the tropical atmosphere are discussed by using an absolute ageostrophic, baroclinic model. Here, SST effects include sea surface heating and forcing of SST anomalies (SSTAs). Studies of the influences of sea surface heating on LFO frequency and stability show that sea surface heating can slow the speed of waves and lower their frequency when SST is comparatively low; while higher SST leads to unstable waves and less periods of LFO. Since the impact of a SSTA on ultra-long waves is more evident than that on kilometer-scale waves, long-wave approximation is used when we continue to study the effect of SSTAs. Results indicate that SSTAs can lead to a longer period of LFO, and make waves unstable. In other words, positive (negative) SSTAs can make waves decay (grow).     

中国大陆黑碳气溶胶排放清单

The detailed high-resolution emission inventory of black carbon (BC) from China in the year 2000 was calculated. The latest fuel consumption data including fossil and biomass fuels, and socio-economic statistics used were obtained from government agencies, mostly at the county level, and some new emission factors (Efs) from local measurements were also used. National and regional summaries of emissions were presented at 0.2°×0.2°resolution. Total BC emission was 1499.4 Gg in 2000, mainly due to the burning of coal and biomass. The BC emission estimated here is higher than those in previous studies, mainly because the emissions from coal burning by rural industries and residences were previously underestimated. More BC aerosols were emitted from eastern China than western China. A strong seasonal dependence was observed for BC emissions, with peaks in January and December and low emissions in July and August; and this seasonality is mainly due to patterns in residential heating and the open burning of crop residues.     

Seasonal Variation of the East Asian Subtropical Westerly Jet and Its Association with the Heating Field over East Asia

The structure and seasonal variation of the East Asian Subtropical Westerly Jet （EAWJ） and associations with heating fields over East Asia are examined by using NCEP/NCAR reanalysis data. Obvious differences exist in the westerly jet intensity and location in different regions and seasons due to the ocean-land distribution and seasonal thermal contrast, as well as the dynamic and thermodynamic impacts of the Tibetan Plateau. In winter, the EAWJ center is situated over the western Pacific Ocean and the intensity is reduced gradually from east to west over the East Asian region. In summer, the EAWJ center is located over the north of the Tibetan Plateau and the jet intensity is reduced evidently compared with that in winter. The EAWJ seasonal evolution is characterized by the obvious longitudinal inconsistency of the northward migration and in-phase southward retreat of the EAWJ axis. A good correspondence between the seasonal variations of EAWJ and the meridional differences of air temperature （MDT） in the mid-upper troposphere demonstrates that the MDT is the basic reason for the seasonal variation of EAWJ. Correlation analyses indicate that the Kuroshio Current region to the south of Japan and the Tibetan Plateau are the key areas for the variations of the EAWJ intensities in winter and in summer, respectively. The strong sensible and latent heating in the Kuroshio Current region is closely related to the intensification of EAWJ in winter. In summer, strong sensible heating in the Tibetan Plateau corresponds to the EAWJ strengthening and southward shift, while the weak sensible heating in the Tibetan Plateau is consistent with the EAWJ weakening and northward migration.     

A Modeling Study of Climatic Change and Its Implication for Agriculture in C

The trends and features of China’s climatic change in the past and future are analysed by applying station obser-vations and GCM simulation results. Nationally, the country has warmed by 0.3oC in annual mean air temperature and decreased by 5% in annual precipitation over 1951-1990. Regionally, temperature change has varied from a cooling of 0.3oC in Southwest China to a warming of 1.0oC in Northeast China. With the exception of South China, all regions of China have shown a declination in precipitation. Climatic change has the features of increasing remark-ably in winter temperature and decreasing obviously in summer precipitation. Under doubled CO2 concentration, climatic change in China will tend to be warmer and moister, with increases of 4.5oC in annual mean air temperature and 11% in annual precipitation on the national scale. Future climatic change will reduce the temporal and spatial differences of climatic factors.     

Characteristics of the Onset of the Asian Summer Monsoon and the Importance of Asian-Australian “Land Bridge”

Based on summarizing previous achievements and using data as long and new as possible, the onset characteristics of Asian summer monsoon and the role of Asian-Australian “land bridge” in the onset of summer monsoon are further discussed. In particular, the earliest onset area of Asian summer monsoon is comparatively analyzed, and the sudden and progressive characteristics of the onset of summer monsoon in different regions are discussed. Furthermore, the relationships among such critical events during the onset of Asian summer monsoon as the splitting of subtropical high belt over the Bay of Bengal (BOB), the initiation of convection over Indo-China Peninsula, the westward advance, reestablishment of South Asian High, and the rapid northward progression of convection originated from Sumatra in early summer are studied. The important impact of the proper collocation of the latent heating over Indo-China Peninsula and the sensible heating over Indian Peninsula on the splitting of the subtropical high belt, the deepening of BOB trough, the activating of Sri Lanka vortex (twin vortexes in the Northern and Southern Hemispheres), and the subsequent onset of South China Sea summer monsoon are emphasized.     

The Diabatic Heating and the Generation of Available Potential Energy: Results from NCEP Reanalysis

In the existing studies on the atmospheric energy cycle, the attention to the generation of available potential energy (APE) is restricted to its global mean value. The geographical distributions of the generation of APE and its mechanism of formation are investigated by using the three-dimensional NCEP/NCAR diabatic heating reanalysis in this study. The results show that the contributions from sensible heating and net radiation to the generation of zonal and time-mean APE (Gz) are mainly located in high and middle latitudes with an opposite sign, while the latent heating shows a dominant effect on Gz mainly in the tropics and high latitudes where the contributions from the middle and upper tropospheres are also contrary to that from the low troposphere. In high latitudes, the Gz is much stronger for the Winter Hemisphere than for the Summer Hemisphere, and this is consistent with the asymmetrical feature shown by the reservoir- of zonal and time-mean APE in two hemispheres, which suggests that the generation of APE plays a fundamental role in maintaining the APE in the global atmospheric energy cycle. The same contributions to the generation of stationary eddy APE (GSE) from the different regions related to the maintenance of longitudinal temperature contrast are likely arisen by different physics. Specifically, the positive contributions to GSE from the latent heating in the western tropical Pacific and from the sensible heating over land are dominated by the heating at warm regions, whereas those from the latent heating in the eastern tropical Pacific and from the sensitive heating over the oceans are dominated by the cooling at cold regions. Thus, our findings provide an observational estimate of the generation of eddy APE to identify the regional contributions in the climate simulations because it might be correct for the wrong reasons in the general circulation model (GCM). The largest positive contributions to the generation of transient eddy APE (GTE) are found to be at middle latitudes in the middle and upper tropospheres, where reside the strong local contributions to the baroclinic conversion from transient eddy APE to transient eddy kinetic energy and the resulting transient eddy kinetic energy.     

THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND ITS POSSIBLE MECHANISM

Using NCEP/NCAR daily reanalysis data and SCSMEX data, an investigation is carried out of the relationship between the position variation of the west Pacific subtropical high (WPSH) and the apparent heating in June 1998 based on the complete vertical vorticity equation. It is found that the non-adiabatic heating plays an important role in the position variation of WPSH. In comparison with climatic mean status, the vertical change of non-adiabatic heating is stronger in the north side of WPSH in June 1998, but weaker in the south side of WPSH. The anomalous non-uniform heating induces anomalous cyclonic vorticity in South China, areas to the south of the Yangtze and its mid-lower valleys, but anomalous anticyclonic vorticity in the Indo-China Peninsula and South China Sea areas lead to the more southward position of WPSH than the mean.     

Scaling the Microphysics Equations and Analyzing the Variability of Hydrometeor Production Rates in a Controlled Parameter Space

A set of microphysics equations is scaled based on the convective length and velocity scales.Comparisons are made among the dynamical transport and various microphysical processes.From the scaling analysis,it becomes apparent which parameterized microphysical processes present off-scaled influences in the integration of the set of microphysics equations. The variabilities of the parameterized microphysical processes are also studied using the approach of a controlled parameter space.Given macroscopic dynamic and thermodynamic conditions in different regions of convective storms,it is possible to analyze and compare vertical profiles of these processes.Bulk diabatic heating profiles for a cumulus convective updraft and downdraft are also derived from this analysis. From the two different angles,the scale analysis and the controlled-parameter space approach can both provide an insight into and an understanding of microphysics parameterizations.     

On the Multiple Equilibrium of the Development of Tropical Cyclone in Nonlinear CISK Model

By using non-static atmosphere equations including basic current, heating force and friction, we discuss the balance amplitude of vertical motion in the conditions of constant heating force, linear and non-linear interaction between large-scale ascending motion and diabatic heating force. In the non-linear condition, the multiple equilibrium feature of the tropical cyclone development is discussed and the reason of the sudden varying of tropical cyclone intensity is studied preliminarily.     

Possible Impacts of the Arctic Oscillation on the Interdecadal Variation of Summer Monsoon Rainfall in East Asia

The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the variation of the AO index and the leading principal component time series of the summer rainfall in East Asia, The rainfall anomaly changed from below normal to above normal in central China, the southern part of northeastern China and the Korean peninsula around 1978. However,the opposite interdecadal variation was found in the rainfall anomaly in North China and South China.The interdecadal variation of summer rainfall is associated with the weakening of the East Asia summer monsoon circulation. It is indicated that the interdecadal variation of the AO exerts an influence on the weakening of the monsoon circulation. The recent trend in the AO toward its high-index polarity during the past two decades plays important roles in the land-sea contrast anomalies and wintertime precipitation anomaly. The mid- and high-latitude regions of the Asian continent are warming, while the low-latitude regions are cooling in winter and spring along with the AO entering its high-index polarity after the late 1970s. In the meantime, the precipitation over the Tibetan Plateau and South China is excessive, implying an increase of soil moisture. The cooling tendency of the land in the southern part of Asia will persist until summer because of the memory of soil moisture. So the warming of the Asian continent is relatively slow in summer. Moreover, the Indian Ocean and Pacific Ocean which are located southward and eastward of the Asian land, are warming from winter to summer. This suggests that the contrast between the land and sea is decreased in summer. The interdecadal decrease of the land-sea heat contrast finally leads to the weakening of the East Asia summer monsoon circulation.     

A study on response of precipitation in china to monsoon intraseasonal oscillation北大核心CSCD

Temporal and spatial evolution characteristics of the 30-60 day oscillation (intraseasonal oscillation, ISO) of summer rainfall in China and the effects of East Asian monsoon on the rainfall ISO are analyzed in this paper. Results show that the annual and decadal variations of the oscillation exist between 1960 and 2008, and the intensity is weakest in the late 1970s and early 1980s. In the typical strong years of the rainfall ISO obtained from empirical orthogonal functions (EOF mode 1), an anticyclone is in northwestern Pacific and a cyclone is in the east of China. In the typical weak years, the wind ISO is much weaker. The low-frequency zonal wind and water vapor transport from the low latitudes to mid-latitudes in the typical strong years, and the oscillation strength of diabatic heating is much stronger than that in the weak years of the rainfall ISO. The anomaly characteristics of the rainfall ISO show anti-phases between the Yangtze River basin and south of China. As for the typical strong years of the rainfall ISO in the Yangtze River basin (EOF mode 2), the main oscillation center of water vapor is in the east of China (20-30°N, 110-130°E). In the peak (break) phase of the rainfall oscillation, a low-frequency cyclone (anticyclone) is in the Yangtze River basin and an anticyclone (cyclone) is near Taiwan Island. In addition, the peak rainfall corresponds to the heat source in the Yangtze River basin and the heat sink in the Qinghai-Tibet Plateau. As for the typical strong years of the rainfall ISO in the south of China, the main oscillation center of water vapor is south of 20°N. In the peak (break) phase of the rainfall ISO, a low-frequency cyclone (anticyclone) is in the south of China and an anticyclone (cyclone) is in the Philippines. The peak rainfall corresponds to the heat source in the south of China and the South China Sea, and the heat sink in the west of Indochina.     

The Structure of Low Frequency Phenomena in the Tropics and Its Interaction with the Extratropics

The structure of planetary scale low freonency phenomena in the tropics is studied, and an attempt is made to determine its influence and interactions with phenomena at higher latitudes.In the tropics, it is found that the majority of the variance in the zonal wind structure is made up in wave numbers I and 2. During warm events in the Pacific Ocean, when the Southern Oscillation Index is negative, almost all of the variance resides in the gravest mode which undergoes a 40° eastward phase shift. Meanwhile, the second logitudinal mode almost disappears. On the other hand, the meridional wind field possesses maximum amplitude at higher wave numbers. However, near the equator,the amplitude is small with extreme values occurring in the subtropics. The difference in scale and the location of cxtrcma of the meridional and zonal wind components indicate that the tropical atmosphere is responding to two different driving mechanisms.Correlation analyses between variations of the zonal wind at reference points a     

Constructions and Applied Examinations of a Kind of Square-Conservative Schemes in High Precision in the Time Direction

In order to meet the needs of work in numerical weather forecast and in numerical simulations for climate change and ocean current, a kind of difference scheme in high precision in the time direction developed from the completely square-conservative difference scheme in explicit way is built by means of the Taylor expansion. A numerical test with 4-wave Rossby-Haurwitz waves on them and an application of them on the monthly mean current the of South China Sea are carried out, from which, it is found that not only do the new schemes have high harmony and approximate precision but also can the time step of the schemes be lengthened and can much computational time be saved. Therefore, they are worth generalizing and applying.