REASONS FOR THE LATE ONSET AND ANOMALOUS SOUTHWARD PERSISTENCE OF THE SOUTH CHINA SEA SUMMER MONSOON IN 2005

Features of atmospheric circulation and thermal structures are discussed using the NCAR/NCEP data to reveal the reasons for the late onset and anomalous southward persistence of the South China Sea Summer Monsoon(SCSSM) in 2005.The results show that three factors are crucial.First,a strong Arabian High overlaps with a high-latitude blocking high and channels strong cold air to southern Asia.Second,the Tibetan Plateau has a bigger snow cover than usual in spring and the melting of snow cools down the surface.Third,the Somali Jet breaks out at a much later date,being not conducive to convection over Indochina.The former two factors restrict atmospheric sensible heating over the Tibetan Plateau and nearby regions while the third one limits latent heating over Indochina.All of the factors slow down atmospheric warming and postpone the onset of SCSSM.Long after the onset of SCSSM,strong cold air over India advances the Southwest Monsoon northward slowly,resulting in weaker convection and latent heating over the Tibetan Plateau and nearby areas.The negative feedback conversely inhibits further northward movement of Southwest Monsoon.

Public Perceptions of Cryosphere Change and the Selection of Adaptation Measures in the rmqi River Basin

This study focuses on the characters of public perceptions on climate and cryosphere change,which are based on a questionnaire survey in the(U|¨)r(u|¨)mqi River Basin.In comparison with scientific observation results of climate and cryosphere change,this paper analyzes the possible impact of the change on water resources and agriculture production in the area.Perceptions of most respondents on climate and cryosphere changes confirm the main objective facts.For the selection of adaptation measures addressing the shortage of water resource,the results are as follows:most people preferred to choose the measures like "policy change" and "basic facility construction" which are mostly implemented by the government and the policy-making department;some people showed more preference to the measures of avoiding unfavorable natural environment,such as finding job in or migrating to other places.The urgency of personal participation in the adaptation measures is still inadequate.Some adaptation measures should be implemented in line with local conditions and require the organic combination of "resource-development" with "water-saving".

Re-Discussion on East Asian Meiyu Rainy Season

In this paper,the synoptic-climatology of Meiyu in East Asia is discussed.It is proposed that the location of the rain band of Meiyu is stable from the viewpoint of climatology,even though the active(wet)and break(dry)Meiyu are influenced by synoptic systems.The duration and the onset and retreat dates of Meiyu exhibit tremendous interannual variabilities,and thus,they are almost unpredictable in seasonal climate prediction.The Meiyu has been used as a synoptic concept and applied to the operational forecast for many decades by meteorological agencies in East Asian countries.As a result,the prediction of the onset and retreat dates of Meiyu has become an important operational work for meteorological services.This has also misled the public’s and scientists’attention.The northward propagation of the East Asian summer monsoon(EASM)surge associated with the intraseasonal oscillation is closely related to the active and break Meiyu.The activities and propagation of the EASM surge modulate the active/break Meiyu that cause concentrative severe precipitation processes and floods or droughts;hence,the authors suggest changing the current forecasting methodology of Meiyu.It is more meaningful from the scientific as well as application viewpoints to establish the monitoring and forecasting of the EASM surge to replace the current operational forecast of Meiyu after the seasonal progress enters the climatological Meiyu period in a year.

ON THE KEY REGIONS OF 500 hPa GEOPOTENTIAL HEIGHTS OVER NORTHERN HEMISPHERE IN WINTER

Variance analysis, correlation analysis and regression analysis methods are applied to analyze the variation of circulation at 500 hPa. In winter, there are three regions (180°E – 150°W, 45°N – 60°N, 70°W – 100 °W,45°N – 75°N, 60°E – 100°E, 65°N – 80°N) whose variations are strong. Those regions are the key regions in which atmospheric circulation can change. Those regions are correlated to some teleconnections and can present a part of variations of 500 hPa to some degree. The linear contemporary correlation between those regions and the height at 500 hPa is significant. Those regions can account for 88 % of variations of concurrent height at 500 hPa. Those regions can present and forecast some variations to some degree in March and April. The longer the time interval, the worse the forecast effect will be. The interannual variations of Q1, Q2 and the SST are weak in the western Pacific.

THE INFLUENCE OF PERSISTENT ANOMALY OF MJO ON ENSO

In this study,two possible persistent anomalies of the Madden-Julian Oscillation mode(MJO) are found in the summer season(persistently Pacific active and Indian Ocean active),and an index is set to define the intensity of the two modes.They are proved to have high statistical correlations to the later ENSO events in the autumn and winter seasons:When persistent anomaly of MJO happens in the Pacific Ocean in summer,El Nino events are often induced during the autumn and winter seasons of that year.However,during the other MJO mode when the summer persistent anomaly of MJO occurs in the Indian Ocean,La Nina events often follow instead.The analysis of the atmospheric circulation field indicates that persistent anomaly of MJO can probably affect the entire Equatorial Pacific circulation,and results in wind stress anomalies.The wind stress anomalies could excite warm or cold water masses which propagate eastwards at the subsurface ocean.The accumulation of warm or cold subsurface water in the Equatorial Eastern Pacific Ocean may eventually lead to the formation of an ENSO.

Design and Implementation of Linux Access Control Model

In this paper,the design and implementation of an access control model for Linux system are discussed in detail. The design is based on the RBAC model and combines with the inherent characteristics of the Linux system,and the support for the process and role transition is added.The core idea of the model is that the file is divided into different categories,and access authority of every category is distributed to several roles.Then,roles are assigned to users of the system,and the role of the user can be transited from one to another by running the executable file.

Interannual and Interdecadal Variations in Atmospheric Circulation Factors and Rainfall in China and Their Relationship

Wavelet analysis is used to study the interannual and interdecadal variations of rainfall in China and atmospheric circulation factors, including the key atmospheric oscillations, W, C, E patterns and subtropical high. Regression analysis and correlation analysis are both used to study the relationship of atmospheric circulation factors and China rainfall on different time scale and spatial scale. The results are as follows:(1) The variations of atmospheric circulation and rainfall in China are characterized by interannual and interdecadal scales. The variations of atmospheric circulation and rainfall are composed of interannual and interdecadal variations. It is necessary to separate those two time scales when climate changes and forecast are studied. (2) The variations of China rainfall are due to the interaction of multi-factors rather than single factors. The marked factors which influence the interannual and interdecadal variations are various.Subtropical high is one of the marked factors which influence interannual variations of rainfall, while AO,NAO, and NPO are one of the marked factors which influence interdecadal variations of rainfall. (3) The longer the time scale is, and the larger the spatial scale is, and the more remarkable the relationships between atmospheric circulation and rainfall are.

Spatial and Temporal Variations of Atmospheric Angular Momentum and Its Relation to the Earth Length of Day

The characteristics of atmospheric-angular-momentum(AAM) and length-of-day(LOD) on different timescales are investigated in this paper,on the basis of the NECP/NCAR reanalysis data and an LOD dataset for 1962-2010.The variation and overall trend of the AAM anomaly(AAMA) at different latitudes are presented,and the relationship between AAMA and LOD is discussed.The AAMAs in different latitude regions exhibit different patterns of variation,and the AAMA in the tropics makes a dominant contribution to the global AAMA.In the tropics,the AAMA propagates poleward to the extratropical regions.It is confirmed that a downward propagation of the AAMA occurs in the lower stratosphere.Correlation analysis shows that the relationship between AAMA and LOD varies significantly on different timescales.Specifically,the tropical AAMA is positively correlated with LOD on short timescales,but they are not obviously correlated on long timescales.This indicates that the interaction between AAM and the earth's angular momentum follows the conservative restriction on short timescales,but the influence of the earth angular momentum on that of the atmosphere depends on the interaction process on long timescales.

STUDY ON THE PHYSICAL PROCESS OF WINTER VALLEY FOG IN XISHUANGBANNA REGION

Xishuangbanna of Yunnan Province is a famous tropical foggy region. A field experiment wascarried out from November 23 to 30 of 1997 during which fogs occurred regularly every day. In thepaper the characteristics of macrostructure of fog are analyzed and the physical processes offormation and dissipation of fog are studied. The results show that the Xishuangbanna valley fogforms firstly in the lower atmosphere with two-layer structures and then develops suddenly in thevertical direction after reaching the ground. Furthermore, the vegetation effect on the formationand dissipation of fog is discussed specially.

COMPARISON OF SIMULATING MINERAL DUST AEROSOLS IN EAST ASIA BY TWO EMISSION SCHEMES

Two common surface-dust emission schemes using critical wind speed and friction velocity were com-pared with the regional climate model RegCM3 in East Asia. In the comparison, transport of mineral dust and its distri-bution were simulated from March to April, 2001. Simulation results were also compared with TOMS aerosol index, showing that obvious differences exist in dust emission quantity and its column burden simulated by the dust emission schemes of friction velocity and wind speed criteria. The results obtained by the wind speed criterion are higher than that by friction velocity, bringing forth the problem whether or not the dust emission scheme matches the model. The obvious difference in the two schemes also explains the uncertainty of simulating mineral dust aerosol by modeling.

Relationship Between the Number of Summer Typhoons Engendered over the Northwest Pacific and South China Sea and Main Climatic Conditions in the Preceding Winter and Spring

Based on the monthly NCEP/NCAR reanalysis data,OLR(outgoing longwave radiation)data,and tropical cyclone data from the Typhoon Annual and Tropical Cyclone Annual edited by China Meteorological Administration,the relationship between the number of tropical cyclones(with the strongest wind≥17 m s^(-1),including tropical storm,strong tropical storm,and typhoon,simply called typhoon in this paper) engendered over the Northwest Pacific and South China Sea in summer and the associated climate conditions is studied.First,the characteristics and differences of the climatic conditions between the years with more typhoons and those with fewer typhoons are compared.The results show that the summer typhoon has a close relationship with SST(sea surface temperature)and ITCZ(intertropical convergence zone)anomalies in the preceding winter and spring.With a La Nina like SST anomaly(SSTA)pattern in the preceding winter and spring,the ITCZ will move northwestward and be enhanced around 160°E in the equatorial central Pacific from the preceding winter to spring.The activity of the Pacific ITCZ is in general stronger and its location is more northward than usual,especially in the typhoon genesis region in West Pacific. This background is propitious to have more typhoons in summer.On the other hand,an El Ni(?)o like SSTA pattern in the preceding winter will be companied with weaker ITCZ activities,and its location is more southward over the equatorial western Pacific from the preceding winter to spring;this background is propitious to have fewer typhoons in summer.In the year with more typhoons,the warm SST over West Pacific in the preceding winter provides a favorable condition for typhoon fromation in the following summer.It enhances the convergence in the troposphere and increases the water vapor supply to the warm SST region.In the following spring,the perturbation of the tropical ITCZ plays a more important role. When the ITCZ moves northward in spring,anomalous convergence will appear over the warm SST region and inspire the positive feedback between the large-scale moisture flux at low levels and the latent heat release in the atmosphere,which benefits the typhoon genesis in summer.Otherwise,if cold SST maintains over the northwestern Pacific during the preceding winter and spring,the convergence in the troposphere is disfavored and the water vapor supply to the cold SST region is reduced,which will bring about weaker ITCZ activities and the perturbation is lacking in the following spring.It then results in fewer summer typhoons.

VARIATIONS OF ATMOSPHERIC OSCILLATION FACTORS AND 500 HPA CIRCULATION PATTERNS AND THEIR RELATIONS

Wavelet analysis,EOF and CCA are used to analyze the variations of atmospheric circulation factors,including the key atmospheric oscillations,W,C,E and subtropical high (SH),and their relationships.The results are shown that the variations of atmospheric circulation factors both in troposphere and lower atmosphere layer are different on different time scales.The most significant variation of atmospheric circulation factors is in the period less than 7 years.The correlation relations of atmospheric circulation factors are different on different time scales.Combination patterns of circulation factors have impact on the relationships of factors.There are lag correlations between combination patterns of circulation factors in former year and that of in next year.

Cold Air Activities in July 2004 and Its Impact on Intense Rainfalls over Southwest China

在 2004 年 7 月的仲夏和在重降水的形成的冷空气的角色的严重降雨事件被使用中国和 NCEP/NCAR 分析的每天观察的降水数据调查。在西南中国的严重降雨是的结果表演仔细，与冷空气有关，从中间高度的纬度的活动，和事件发生在中间高度的纬度循环和低纬度的合作效果下面摘要的政体。它是合并一个冷旋涡在上与向北方登陆的台风和东方西南中国中间纬度旋涡，以及从进那分别地引起中间高度的大气的循环的三大改变在的正直的横过的马槽的突然的转变早、中间十天这个月。然后，长波浪的振幅很快放大，导致到在仲夏的低纬度的区域的冷空气的不平常的侵入。同时，温暖、潮湿的西南夏天季风是相当活跃的。在西南中国上的冷空气和夏天季风的强壮的相互作用在冷空气的南部的方面上导致大规模对流降雨。关于冷空气的活动，它能以三个突出的方法影响降雨。第一，上层的冷空气的进入被部分南方的上层的喷气经常伴随。相应第二等的发行量的上升分支，在喷气中心的左前面方面上，为降雨提供喜爱的动态向上的运动。第二，冷空气的向南方的运动贡献大气的 baroclinic 结构的建立，它将导致 baroclinic 骚乱。与冷空气的侵入联系的大气的骚乱能破坏潜在的不稳定性层化，释放对流可得到的势能(披肩) 并且最后引起对流活动。另外，在与在底层的潮湿、温暖的空气的移流一起的上面的水平的干燥、冷的空气的移流过程为在降水区域的潜在的不稳定性的重建是相当重要的，它是贡献坚持的降雨的关键因素之一。

Simulation of the direct effects of dust aerosol on climate in East Asia

The results from some general circulation models show distinct radiative forcing(RF) by dust aerosol,which potentially has an effect on climate change.The direct RF and regional climatic effects of dust aerosol over the East Asian region are investigated in this study using NCAR's Community Atmospheric Model version 3.1.The negative RF at the top of the atmosphere(TOA) and the surface(SRF) has been revealed except for some high-albedo regions,which leads to a decrease in the surface air temperature and brings an increase of atmospheric radiative heating under both clear-and all-sky conditions.The decrease in the surface air temperature can be found over a wide region that includes the Indian peninsula and northwest China.It accompanies an increase in eastern China and the Korean peninsula,and temperature changes are not limited to regions with a large dust optical depth.A belt of vapor increase is revealed from the Indian peninsula extending east to northern China,while vapor content evidently deceases in southwest China.An increase in precipitation can also be found in the belt of increased vapor accompanying the reduction of precipitation across the regions to the south of 30oN.The pattern of rainfall change helps to offset the trend of increasing wetness in the south and increasing dryness in the north of China in recent years.

Influence of Springtime Atlantic SST on ENSO:Role of the Madden-Julian Oscillation

Increased evidence has shown the important role of Atlantic sea surface temperature(SST) in modulating the El Nio-Southern Oscillation(ENSO). Persistent anomalies of summer Madden-Julian Oscillation(MJO) act to link the Atlantic SST anomalies(SSTAs) to ENSO. The Atlantic SSTAs are strongly correlated with the persistent anomalies of summer MJO, and possibly affect MJO in two major ways. One is that an anomalous cyclonic(anticyclonic) circulation appears over the tropical Atlantic Ocean associated with positive(negative) SSTA in spring, and it intensifies(weakens) the Walker circulation. Equatorial updraft anomaly then appears over the Indian Ocean and the eastern Pacific Ocean, intensifying MJO activity over these regions. The other involves a high pressure(low pressure) anomaly associated with the North Atlantic SSTA tripole pattern that is transmitted to the mid-and low-latitudes by a circumglobal teleconnection pattern, leading to strong(weak) convective activity of MJO over the Indian Ocean. The above results offer new viewpoints about the process from springtime Atlantic SSTA signals to summertime atmospheric oscillation, and then to the MJO of tropical atmosphere affecting wintertime Pacific ENSO events, which connects different oceans.

ATMOSPHERIC DIVERGENCE PRODUCTION IN ELECTRIFIED CLOUDS

I. INTRODUCTION The most possible mechanism of the effects of solar variability on weather and tropospheric circulation has been suggested to be an electrical coupling process, because it may bypass many difficulties associated with the heating mechanism in many ways such as energy, coupling and time delays.