Climatic Features of Cloud Water Distribution and Cycle over China

Analyses of cloud water path （CWP） data over China available from the International Satellite Cloud Climatology Project （ISCCP） are performed for the period 1984-2004. Combined with GPCP precipitation data, cloud water cycle index （CWCI） is also calculated. The climatic distributions of CWP are found to be dependent on large-scale circulation, topographical features, water vapor transport and similar distribution features which are found in CWCI except in the Sichuan Basin. Influenced by the Asia monsoon, CWP over China exhibits very large seasonal variations in different regions. The seasonal cycles of CWCI in different regions are consistent and the largest CWCI occurs in July. The long-term trends of CWP and CWCI are investigated, too. Increasing trends of CWP are found during the period with the largest increase found in winter. The decreasing trends of CWCI dominate most regions of China. The differences in long-term trends between CWP and CWCI suggest that CWP only can influence the variation of CWCI to a certain extent and that other factors need to be involved in cloud water cycle researches. This phenomenon reveals the complexity of the hydrological cycle related to cloud water.

Calculation of Solar Albedo and Radiation Equilibrium over the Qinghai-Xizang Plateau and Analysisof Their Climatic Features

Using radiation data from the Automatic Weather Stations (AWSs) for thermal balance obser-vations, which were set up at Lhasa, Nagqu, Xigaze and Nyingchi by the Sino-Japanese Asian Monsoon Mechanism Co-operative Project in 1993–1996, and 1985–1989 Earth Radiation Balance Experiment (ERBE) measurements of Langley Research Center/NASA of US, and 1961–1996 monthly mean data from 148 surface stations over the Qinghai-Xizang Plateau (QXP) and its neighborhood, study is performed on empirical calculation methods of surface albedo, surface total radiation, planetary albedo and outgoing longwave radiation with the climatic features of radiation balance at the surface and the atmospheric top examined. Evidences suggest that the empirical formulae for surface albedo, planetary albedo, surface to-tal radiation and outgoing longwave radiation from the atmospheric top are capable of describing their seasonal and interannual variations over the QXP. The surface albedo is marked by noticeable seasonal variation and yearly mean of 0.22 with the maximum of 0.29 in January and minimum of 0.17 in July and August; in winter the albedo has great horizontal difference, bigger in the moun-tains than in the river valleys, and small in summer. The planetary albedo shows a smaller range of its annual variation with the yearly mean of 0.37, the maximum (minimum) occurring in February and March (autumn). In winter its high-value regions are mainly at Gar (Shiquanhe) in the western QXP and from the southwestern Qinghai to the northeastern Tibet and the low-value area at the northern slope of the central Himalayas; in summer, however, the albedo distribution displays clear-ly a progressive decrease from southeast to northwest. As for the surface total radiation, its values and annual varying range are smaller in the east than in the southwest. Its high-value center is at the southern slope of the Himalayas in winter and makes a conspicuous westward migration in spr-ing, remaining there for a long time, and it begins to retreat eastward in autumn. Monthly mean values of the surface net radiation are all positive and larger in summer than in winter. The net ra-diation is significantly intensified under the combined effect of surface total radiation and surface albedo from spring to early summer, resulting in the strongest sector in the mid plateau with its center staying nearly motionless from March to September, and is reduced in autumn dominantly by surface effective radiation. The earth-atmosphere system loses heat outward from October to next February and gains in other months. On an average, the plateau gains heat of 15 W m-2 on an annual basis. Key words The Qinghai-Xizang Plateau - Albedo - Radiation balance - Climatic feature (1)This work was supported under the auspices of the National (G1998040800) and CAS’s Key Project for Basic Research on Tibetan Plateau (KZ951-A1-204; KZ95T-06).

STUDY ON CLIMATIC FEATURES OF SURFACE TURBULENT HEAT EXCHANGE COEFFICIENTS AND SURFACE THERMAL SOURCES OVER THE QINGHAI-XIZANG PLATEAU

Using monthly mean of surface turbulent heat exchange coefficients calculated based on data from four automatic weather stations(AWS)for thermal equilibrium observation in July 1993— September 1996 and of surface conventional measurements,an empirical expression is established for such coefficients.With the expression,the heat exchange coefficients and the components of surface thermal source are computed in terms of 1961—1990 monthly mean conventional data from 148 stations over the Qinghai-Xizang(Tibetan)Plateau(QXP)and its adjoining areas,and the 1961—1990 climatic means are examined. Evidence suggests that the empirical expression is capable of showing the variation of the heat exchange coefficient in a climatic context.The monthly variation of the coefficients averaged over the QXP is in a range of 4×10^(-3)-5×10^(-3).The wintertime values are bigger in the mountains than in the valleys and reversal in summer.Surface effective radiation and sensible heat are the dominant factors of surface total heat.In spring surface sensible heat is enhanced quickly, resulting in two innegligible regions of sensible heat,one in the west QXP and the other in northern Tibet.with their maximums emerging in different months.In spring and summer sensible heat and surface effective radiation are higher in the west than in the east.The effective radiation peaks for the east in October—December and the whole QXP and in June and October for the west.The surface total heat of the plateau maximizes in May.minimizes in December and January,and shows seasonal variation more remarkable in the SW compared to the eastern part.In the SW plateau the total heat is much more intense than the eastern counterpart in all the seasons except winter.Under the effect of the sensible heat,the total heat on the SW plateau starts to considerably intensify in February,which leads to a predominant heating region in the west,with its center experiencing a noticeable westward migration early in summer and twice pronounced weakening in July and after October.However,the weakening courses are owing to different causes.The total heat over the north of QXP is greatly strengthened in March.thus generating another significant thermal region in the plateau.

CLIMATIC FEATURES OF SEA TEMPERATURE OF WARM POOL AND RELATIONSHIP WITH SST OF ITS ADJACENT REGIONS

In this paper,climatic features of sea temperature of western Pacific warm pool and the relationship with sea surface temperature (SST) of its adjacent regions are analyzed based on the observed sea temperature on vertical cross section along 137°E in western Pacific,the monthly mean SST of Xisha Station in South China Sea and the global monthly mean SST with resolution of 1°×1°(U.K./GISST2.2).The results indicate that (1) in a sense of correlation.SST of western Pacific warm pool can represent its sea subsurface temperature from surface to 200 m-depth level in winter,and it can only represent sea temperature from surface to 70 m depth in summer.The sea subsurface temperature anomaly of warm pool may be more suitable for representing thermal regime of western Pacific warm pool.The sea subsurface temperature of warm pool has a characteristic of quasi-biennial oscillation.(2)Warm pool and Kuroshio current are subject to different ocean current systems (3)Furthermore,the relationship between SST of Xisha Station and SST of warm pool has a characteristic of negative correlation in winter and positive correlation in summer,and a better lag negative correlation of SST of Xisha Station with sea subsurface temperature of warm pool exists.(4)Additionally,oscillation structure of sea temperature like “a seesaw” exists in between warm pool and Regions Nino3 and Nino4.January (June) maximum (minimum) sea subsurface temperature anomaly of warm pool may serve as a strong signal that indicates maturity phase (development phase) of La Nina (El Nino) event,it also acts as a strong signal which reveals variations of SST of Regions Nino3 and Nino4.

Diversity patterns of cushion plants on the Qinghai-Tibet Plateau:A basic study for future conservation efforts on alpine ecosystems

The Qinghai-Tibet Plateau(QTP)is an important cushion plant hotspot.However,the distribution of cushion plants on the QTP is unknown,as are the factors that drive cushion plant distribution,limiting our understanding of the evolution of cushion species in the region.In this study,we assessed spatial patterns of total cushion plant diversity(including taxonomic and phylogenetic)over the entire QTP and compared patterns of diversity of cushion plants with different typologies(i.e.,compact vs.loose).We also examined how these patterns were related to climatic features.Our results indicate that the southern QTP hosts the highest total cushion plant richness,especially in the south-central Hengduan Mountains subregion.The total number of cushion species declines from south to north and from southeast to northwest.Compact cushion plants exhibit similar patterns as the total cushion plant richness,whereas loose cushion plants show random distribution.Cushion plant phylogenetic diversity showed a similar pattern as that of the total cushion plant richness.In addition,cushion plant phylogenetic community structure was clustered in the eastern and southwestern QTP,whereas random or overdispersed in other areas.Climatic features represented by annual energy and water trends,seasonality and extreme environmental factors,had significant effects on cushion plant diversity patterns but limited effects on the phylogenetic community structure,suggesting that climatic features indeed promote the formation of cushion plants.Because cushion plants play vital roles in alpine ecosystems,our findings not only promote our understanding of the evolution and formation of alpine cushion plant diversity but also provide an indispensable foundation for future studies on cushion plant functions and thus alpine ecosystem sustainability in the entire QTP region.

辽西地区区域性大雾气候特征及分析预报(英文)

By using the fog data from 1995 to 2004 of four selected observation stations,the weather features of foggy days in Liaoxi area have been studied in this paper.The favorable surface and upper circulation for fog and its frequency have also been concluded from the statistic.In this paper,the forecasting index of fog,proposed on the basis of the condition and mechanism of the fog occurrence,has been tested by the 10-year analysis.Another test conducted by using the data of 1st July-31st December,2004 also gives a good result which has a vacancy rate of 22.2% and a miss rate of 5.1%.

A Study on Typhoon-Induced Rainfalls over Beijing:Statistics and Case Analysis

Based on the Shanghai Typhoon Institute （STI） Typhoon Year t3ook and typhoon precipitation data, Japan Meteorological Agency satellite TBB data, and National Centers for Environmental Prediction （NCEP） reanalysis data, the climatic characteristics of rainfalls in Beijing associated with typhoons were analyzed for the period 1949-2006, and two typhoon cases with remarkable differences in rainfall intensity over Bei- jing were compared and diagnosed. The 58-yr statistical results show that rainfall events associated with typhoons occurred in Beijing about once every three years during June-September. These typhoons were mainly active in the region 20°- 50°N, 109°- 128°E and most of them moved northwestward while the others turned to the northeast. The typhoon rainfall over Beijing in general sustained for 2 5 days. Typhoon centers were usually located in the areas from Jiangxi to Anhui, the Yellow Sea, or near Beijing, when rain- storms occurred over Beijing. Case study indicates that the 2-day torrential rainfall event that happened in Beijing in 1984 was due to the interaction between Typhoon Freda （8407） and a westerly trough, while only a medium-strength rainfall event occurred in Beijing in 2005 in spite of the dominating cyclonic circulation of Typhoon Matsa （0509） directly over Beijing. It is found that both Preda and Matsa underwent extra- tropical transition and possessed an asymmetric structure. The rainfall difference was caused by the fact that Beijing was located in different convective development areas of the two typhoons. On the other hand, the lifting conditions were different although plentiful atmospheric moisture and convective unstable energy existed over Beijing during both events. The ascending motion of warm southerly in Beijing was stronger and deeper and a larger vertical wind shear was associated with Typhoon Freda. However, the lifting of water vapor was restrained by the descending motion of northerly cold airflow in Beijing under the impact of Typhoon Matsa. Besides, it is also found that topography played an important role in the typhoon rainfall over Beijing.

Characteristics of rainstorm in Fujian induced by typhoon passing through Taiwan Island

Based on the typhoon track and intensity data and the precipitation data of typhoon in China during 1961–2020,the overall characteristics of the rainstorm in Fujian caused by typhoon passing though Taiwan Island were studied.More than 80 percent of typhoons passing though the Taiwan Island can bring heavy rain to Fujian.There are 1.5 events of typhoon rainstorm in Fujian every year,and the average annual impact days are 3.0.In terms of spatial distribution,the frequency and intensity of cross-island typhoon rainstorm decrease rapidly from the coastal areas of Fujian to the inland areas,and Zherong,Changle and Jiu xianshan stations in the coastal areas are the high value centers.The typhoon paths of cross-island typhoon rainstorm in Fujian are mainly divided into three categories:landing-Fujian type(including landing-Fujian northeast turning,landing-Fujian middle northbound and landing-Fujian south westbound),landing-Guangdong and Zhejiang type and offshore turning type,among which landing-Fujian type typhoon has the most significant influence(only the landing-Fujian type appears the rainstorm of≥50 mm·(24 h);),and the rainstorm intensity,influence range and asymmetrical structure of the rainstorm are the strongest,the most extensive and the most significant in the landing-Fujian middle northbound path.Based on the NCEP reanalysis data,the comparative analysis of the environmental fields causing the difference of precipitation intensity between the two typhoons landing-Fujian middle northbound and landing-Fujian south westbound shows that:To the landing-Fujian middle northbound track,strong wind speed area on the north side of the typhoon center leads to strong onshore winds,in the role of mountain terrain,piedmont has better convergence and very strong deep vertical upward movement,with better moisture conditions,it can send low high-energy water vapor to the middle,the precipitation dynamics and water vapor conditions are significantly stronger than the landing-Fujian south westbound track,resulting in more typhoon heavy rain.

Future wet grasslands:ecological implications of climate change

Wet grasslands are threatened by future climate change,yet these are vital ecosystems for both conservation and agriculture,providing livelihoods for millions of people.These biologically diverse,transitional wetlands are defined by an abundance of grasses and periodic flooding,and maintained by regular disturbances such as grazing or cutting.This study summarizes relevant climate change scenarios projected by the Intergovernmental Panel on Climate Change and identifies implications for wet grasslands globally and regionally.Climate change is predicted to alter wet grassland hydrology,especially through warming,seasonal precipitation variability,and the severity of extreme events such as droughts and floods.Changes in the diversity,composition,and productivity of vegetation will affect functional and competitive relations between species.Extreme storm or flood events will favor ruderal plant species able to respond rapidly to environmental change.In some regions,wet grasslands may dry out during heatwaves and drought.C4 grasses and invasive species could benefit from warming scenarios,the latter facilitated by disturbances such as droughts,floods,and possibly wildfires.Agriculture will be affected as forage available for livestock will likely become less reliable,necessitating adaptations to cutting and grazing regimes by farmers and conservation managers,and possibly leading to land abandonment.It is recommended that agri-environment schemes,and other policies and practices,are adapted to mitigate climate change,with greater emphasis on water maintenance,flexible management,monitoring,and restoration of resilient wet grasslands.