The study of regional population evolution is helpful to reveal the rule of population distribution and is important for reasonably making population developmental policy, and for the promotion of regional sustainable development. In this paper,firstly, a preliminary study was conducted on population distribution structure according to the third, fourth, fifth census materials, and all previous statistic yearbooks about all cities in the Yangtze River delta area.The population quantity of different cities is quite different, with the density being higher in the north, and with distribution concentrated along traffic axes. Then, characteristics of population distribution and regulation have been particularly analyzed since 1980s. It was shown that there are many differences among the population amplitudes in different cities, with lower increase of population density. The distribution is of concentrationdecentralization pattern, and center of gravity moves from northeast to southwest. Some exterior factors affect the regional population spatial distribution. It was considered that economic factors, status and function, policy, information and traffic factors are the causations resulting in the great changes of regional population spatial distribution.

Based on the famous Environmental Kuznets Curve and in the light of the economical and environmental data from 1985 to 2004 in Nanjing City,the interrelations between economical and environmental factors were analyzed and the dynamic regression models were also established using SPSS and Excel software. The results indicated that the correlation of the discharge amount of industrial waste water and GDP per capital does not fit the inverted "U" Environmental Kuznets Curve, but the "N" shape of cubic model with two turning points, at 9 000 yuan and 29 000 yuan respectively, possibly being the result of rapid change of industry structure. The correlations between the discharge amount of industrial waste gas and solid waste and GDP per capital both fit the Environmental Kuznets Curve well, and their turning points arrive early, being around 30 000 yuan and 39 000 yuan respectively. According to the turning point criterion of $500 in developed countries, the discharge amount of industrial waste gas and solid waste arrive the turning point earlier than in developed countries. As for the discharge amount of industrial "three waste" in Nanjing City, it can be concluded that: not all types of environmental indicators fit the Environmental Kuznets Curve relationship, and only the pollutants of industrial waste gas and solid waste have the character; economical factor only accounts for about 40% of the discharge amount of industrial waste water, and other factors, such as environmental policy and environmental planning, can basically explain about 60% of the discharge amount of industrial waste water; efficient policy and huge investment in environment have brought the turning point forward.

Environmental Kuznets Curve (EKC) illustrates the pattern in changes of the relationship between economic development and environmental degradation. The pattern in changes of environmental quality degrades at the initial stage and then improves with the growth of economy. This paper reviews the progress in this area in respect of empirical research, econometric model and decomposition analysis in China and other countries.With the development of EKC,〖JP2〗environmental proxies expand from environmental〖JP〗 pollutants to resource and ecology proxies and to environmental efficiency proxies, and the inverse Ushaped relationship is not the unique form,which does not fit into all 〖JP2〗environmental proxies.The econometric models used in EKC study are mainly reduced models.The method of emission decomposition analysis can quantify the contribution of each factor in the change of pollution emission, and has been used widely. Although there are great advances in EKC research, some aspects such as the threshold of ecological system, the spatial and temporal transmission of pollution, the multiformality of curve, data processing and econometric model, and environmental policy management still need to be further studied, among which data processing and econometric model are the key factors.

Since 1990, industrial factors have been the key reason causing increasing wideness of regional economic disparity in China. Taking GDP capita as a main indicator, the dynamic changes of regional economic disparities, regional composition and industrial composition were analyzed among the period from 1990 to 2004. The reasons which caused the regional disparity and its dynamics in Chinese economic growth were revealed through industrial structural change and regional concentration. It is revealed that the regional disparity of the second industrial growth determined the regional disparities of Chinese 〖JP2〗economic growth.So,the concentration of nonagricultural〖JP〗 industries were mainly composed of manufacturing enterprises in east China, and the central and western China has gradually become as peripheral areas. Consequently, the regional disparities in terms of Chinese economic growth were widened continually. To accelerate the manufacturing industry in central and western China may reduce the disparity, and therefore solving uneven distribution of regional nonagricultural industries is a key measure to reduce the regional disparity.

Zhoushan Archipelago lies in the Yangtze River Delta. It is the foreland of the confluence of the Yangtze River and the channel of south and north currents, being famous with its three unique marine resources, i.e. fish, port and landscape. The Yangtze River Delta is one of the largest economic core areas in China, but may to some extent subject to the natural environment constraints for the lack of deep water coastline and marine tourism resources. Thus, based on analysis and situsurvey in Zhoushan area, some proposals are put forward on utilization of marine resources in Zhoushan Archipelago： (1) The deep shoreline resources can be used to build international deepwater port for transferring raw materials such as metal ore, coal, and crude oil. Furthermore, they can be also built up as a process industry base relying on harbor for staple goods and a standby deepwater port for transporting goods of the Yangtze River Delta outward. (2) There is a great potential on the development of deepwater aquaculture and offshore fishing. (3) It is an appealing resort for marine tourism especially in holiday relaxation which supplies the gap of tourism in the Yangtze River Delta.

Changes in land use and cover (LUCC) and their effect on ecoenvironment have attracted more and more researchers. This paper is to reveal fast urban landuse changes during the period from 1990 to 2001 in Pudong New Area of Shanghai and their impacts on ecoenvironment by using remote sensing data. Pudong New Area of Shanghai is characteristic of fast urbanization, especially during the period from 1990 to 2001,during which Pudong has undergone a fast urban construction and growth. Using Landsat remote sensing data in 1990 and 2001, after imagery preprocessing, we retrieved land use information through supervised classification in the support of ERDAS IMAGINE software, and mapped the charts of land use classification in this period based on Landsat data. Furthermore, we established the shift matrix of land use changes, analyzed the intensity and extent of changes for land use in Pudong in the period, the pattern in spatial landuse changes, and its impacts on ecoenvironment. It is revealed that the farmland and waterbody decreased sharply from 1990 to 2001 in Pudong. Farmland decreased by 58.16% and waterbody by 17.4%. New urban growth area was mainly converted from farmland and waterbody. 55% of urban expansion was from farmland and 35.26% was from waterbody, which made the most important contribution to urban expansion. The ecoenvironmental effects of urban expansion in this study area were not optimistic. The decrease of waterbody, the pollution of water resources and air, and heat island effects were obvious problems.

Because of the remarkable change in cultivated land in welldeveloped southeast littoral areas, it is of great importance for us to analyze the trend in change of cultivated land and its main driving forces in order to achieve a sustainable economic development in these areas.By choosing Shaoxing City as a typical area, the trend in the change of cultivated land was analyzed with temporal and spatial differences identified. As a result of the principal component analysis and a multiple stepwise regressive analysis, the main driving forces affecting arable land changes were then discussed. The spatialtemporal features of cultivated land change in Shaoxing were notable, and the cultivated land has decreased year by year. Moreover, the reduction in plowland of Shaoxing in recent years was mainly due to the rapid development of economy, the improvement of people's lives and the increase of capital input, that is to say, the marketoriented agricultural restructuring and city construction have occupied the majority of cultivated land. The analytical results and conclusions of this paper will not only provide scientific basis for the rational use of cultivated land and their effective protection for the sustainable development in Shaoxing city, but also provide an important reference for further study on plowland change in the welldeveloped littoral areas of southeast China.

Based on fourperiod TM remote sensing data and GIS spatial analysis methods, the paper described the pattern in urban landuse growth with the analysis of its mechanism in Qinhuai River Basin over last 20 years. Spatial and temporal differences were found in urban landuse growth: growth turning point occurred in the year 1994 and 2000 respectively; growth hot poles and hot belts were detected in the spatial difference; temporal differences were observed in urban landuse growth as a consequence of economical and social development; a relativity coefficient was found high between urban landuse growth ratio and urbanization, GDP, and Development Area. The above dynamics included the development area building, investment growth in 1992 and the administration replacement from county to district in 2000. Urban landuse growth pattern evoluted from economical and social development carriers' changes, and the Development Area was the primary source of urban landuse growth in 1992; Dongshan New Urban District and University City became spatial growth core and new spatial form; and airport and highway networks served as guidance for urban landuse spatial pattern.

Functional evaluation is an effective method for natural reserves in order to improve management and archive their functions. In this paper, using the theory of fuzzy logic and questionnaire surveys, a hierarchical criterion system with three layers and twenty factors was established for fuzzy comprehensive evaluation of functions in the Jiugongshan Nature Reserve. It was shown that the function of this reserve as a whole was in good situation, with the nature conservation and social development also in a good status, but the subfunctions of others were just soso. In order to improve functions of the reserve, we should improve the protection of resources and landscapes, set up new propaganda and education agenda. Overall, five suggestions were proposed to strengthen the function of this reserve.

Affected by development of city and countryside, city fringe area is a special economic and geographical unit, and a major area for city spreading. But, the range of city fringe is uncertain and the method of demarcation is qualitative. In this paper, a model of message entropy for land use was established based on the theory of information entropy and the feature of land use in city fringe. As a case of Jingzhou City in Hubei Province, and by using satellite imagery landsat dated of October 2000, the model of information entropy for land use was applied in combination with remote sensing (RS) and geographic information system (GIS) techniques. Through analyzing the distribution characteristics of entropy, the range of city fringe in Jingzhou is confirmed with the entropy values of 60 and 30. Finally, the range with the area of 124.4 km2 including 25 villages is obtained. With this method, the feature of high precision and real time is shown. If the satellite image of the higher resolution and other model were adopted, the precision of partition should be enhanced.

Comprehensive evaluation of sustainable utilization of water resources is a typical multigoal multilayer and multiattribute decisionmaking problem, with the necessity to consider factors of society, economy, resources and environment. Based on the real status in Yunnan Province, a relative rich region in terms of water resources, a new evaluation index system for sustainable utilization of water resources was set up, by using clustering function of selforganizing and selfadapting of selforganizing neural network. Clustering analysis was conducted in Yunnan Province and in various degrees of water utilization. It is shown that sustainable degree in utilization of water resources in Yunnan Province can be classified into 5 classes, and as a whole, Yunnan Province belongs to class Ⅲ, implying that sustainable utilization of water resources can be maintained in the province on the whole. The model provides us a new method and thought for comprehensive evaluation in sustainable utilization of water resources.[

ccording to economy growth law and development stages，it is unavoidable that the cultivated land will reduce in the Yangtze River Delta as a central area for economy growth in China. The change of grain yield and cultivated land reduction with the economy development in the delta was analyzed by using method of correlation. A conclusion can be drawn that a high peak value of cultivated land conversion rate will appear in the period of “11th fiveyear plan”. Based on national food security judgment, development forecast and the relation between cultivated land and national food security, some suggestions were put forward to protect cultivated land: positive protection policy must be inforced in the Yangtze River Delta during the period of “11th fiveyear plan”, and protection policy should be turned out into strict control during the period of “12th fiveyear plan”. Furthermore, some countermeasures on cultivated land protection were suggested, such as to qualitatively protect cultivated land, to protect ecolandscape function, to increase the exploitation of reserve resource, to reduce nonagricultural cultivated land occupation, and to strengthen the policy management.

By using regression analysis and prognostic theory, the minimum cropland acreage per capita, and cropland pressure index model were analyzed with the consideration of changes in cropland, population and grain output since enforcement of the reforming policy. The cropland, population, grain output, minimum cropland acreage per capita and cropland pressure index were forecasted for the following 15 years. It was found that between 1978 and 2004 both the cropland and the grain output declined in contrast to the annual population growth, resulting in the rise of minimum cropland acreage per capita and pressure index on cropland,and consequently broadening the gap between the grain supply and need.With the rising population and the obvious decline of cropland acreage per capita in the following 15 years, minimum cropland acreage per capita and pressure index on cropland will also show some degree of decline.However, the boost of cropland productivity is at the cost of over exploitation on the cropland, leaving the grain issue still quite critical. Thus, countermeasures for the reduction of cropland pressure, guarantee of grain output security and sustainable development were proposed in this paper.

The willingness of rural households in the conversion of farmland to urban area has greatly 〖JP2〗influenced the reasonable land transmission and then the coordinated development of urban and rural society〖JP〗.The authors conducted a typical analysis on factors influencing the willingness of farm households based on random sample questionnaires in 33 villages,143 households in Wuhan suburb and exurban.By using Logistic models, this paper revealed that the infrastructure and improvement of services and the social security system are the major factors for farmers in these two categories of areas, and the compensation level is an additional factor influencing the farmers' decision. The rational and feasible measures based on the most important factors were proposed: if the need and interest of farmers can be met and considered,〖JP2〗a balance should then be found between urban land demand and farmers' willingness to maintain their farmland.

Zhongyang Sandbank is located on the South and North Passage bifurcation. This section is concentrated with several important projects, such as quay of Shanghai Baosteel Group Corporation and deepwater navigation channel project downstream. Based on topographic maps dating from 1870, utilizing ArcGIS and other GIS software, the paper mainly deals with displacement characters and profile of bifurcation sandbanks including Zhongyang Sandback,Shangliuhe Sandbank and Xinliuhe Sandback and so on. It is found that the evolvement character of Zhongyang Sandbank is “back off  upper shift back off again and so on” circulative evolvement of back off under longterm runoff and going up with accepting bottom sand from upreaches. The area and volume of each sandbank has been calculated, and each channel of the South and North Passage bifurcation has been analyzed. At present, bifurcation is not steady. It is necessary to carry out regulation project as soon as possible in order to stabilize sandbanks and channels and reduce the threat of bottom sand towards downstream.

The objective of this study was to investigate the form and spacial distribution of Cu，by analyzing its characteristics in terms of adsorption，desorption and fixation in different marineface sediment matrix soils in the delta region of the Yangtze River. It was shown that for different kinds of surface and subsurface soils，Cu adsorption was well regressed with the Langmuir，Freundlich and Temkin equations，especially the Langmuir equation，through which the maximum adsorption capacities were in harmony with the experimental results. Meanwhile，the Cu desorption data could be regressed by exponential equation. For most soils，the maximum adsorption capacities of Cu by subsurface soils were larger than those of surface soils，yet their desorption capacities of Cu were less than the latter. The fixed adsorption of Cu for different soils were analyzed: for surface soils，Tantu mud was the maximum of fixed Cu，and the minimum was Tansha mud; for subsurface soils，the maximum was Tanchao mud，and the minimum was Tansha mud. OM，pH and other factors might have an influence on the maximum of fixed Cu of soils. In general，if the soil had higher pH and OM values，its fixed adsorption of Cu was mostly larger than other soils correspondingly.

Taihu Lake，as one of the five largest freshwater lakes in China，is presently confronted with accelerated water eutrophication. After the control of point pollution，farm nonpoint source pollution due to wide application of fertilizers and pesticides has become a major factor affecting the water quality in Taihu Lake. Farm ecosystem control and nonpoint source pollution in Taihu Lake area were reviewed in this paper. It was pointed out that，the loads of farm nonpoint source pollutants will continue to increase，due to the increasing use of chemical fertilizers and more surpluses of nitrogen and phosphorus in the farm of this region. Generally，nitrogen and phosphorus in the field are transported to surface water by means of farm drainage and surface runoff and so on. To control the nonpoint source pollution，the function of harness measures of farm ecosystem management was analyzed. Measures，such as soil testing and fertilizer recommendation，conservation tillage and alternative land use regulations，may play a key role in mitigating farm nonpoint source pollution，so as to provide some basis for controlling farm nonpoint source pollution.

With the grid spatial analysis technique of GIS，the multifactor synthetic evaluation of ecoenvironmental condition was carried out for the whole Taihu Lake，and the spatial distribution internality of ecoenvironmental condition was posted. Firstly，the whole lake was divided into 800 grid cells，and based on the data of 11 factors—including water, organism and sediment—monitored at limited points from 2002 to 2003, the simulative value of all cells was obtained by spatial interpolation by the use of GIS. Secondly，the factor values were combined into a synthetic value for each cell by grid overlay calculation by GIS. By the synthetic value，the cells were divided into five levels including best，better，fair，worse and worst，and the evaluation map of the ecoenvironmental condition of Taihu Lake was obtained. The results showed that the ecoenvironmental quality decreased from southeast to northwest gradually，the area of worse level and worst level accounted for a majority of the lake，and the ecoenvironmental status is poor in general. It was also indicated that the study evaluated the ecoenvironmental quality of Taihu Lake objectively for the results accorded basically with the actual status of the lake.

Based on the process of contamination filtering into soiladose zoneaquifer，geology，physiognomy and hydrogeology have been considered and indexes including depth to water，precipitation recharge，aquifer media，soil media，topography，impact of vadose zone and penetrability coefficients have been selected to establish DPASTIC index system of groundwater vulnerability assessment in Jiujiang City. The approach of fuzzy synthesis using DPASTIC indexes has been established according to fuzzy theory and method. It overcomes difference of rating and discontinuousness on index value and tries to seek optimization of rating and continuous change on parameters. The concept of index standard eigenvalue has been cited in order to determine index rating. Considering the data and information obtained in the study area，index standard eigenvalue matrix which sets corresponding to 10 linguistic classes used for determining the groundwater contamination degree of every parameter has been founded and relative optimization value been established. The map of groundwater vulnerability subarea has been drawn by MAPGIS soft. The distribution pattern of contamination is well consistent with groundwater environment quality forecasted and measured in this area，which has practical meaning for government agencies to set up prevention projects and management steps of groundwater contamination. It is considered that the method used in the present study has reference value to groundwater vulnerability assessment in similar areas.

This paper introduced the forming and developing processes of Honghu Lake and then induced the major factors which influenced the evolution of Honghu Lake.Referred to Honghu Lake，geological activity and flood in the Yangtze River formed the precondition，and the ancient climate promoted the area change and swamp formation.Human activities accelerated the ecological deterioration in modern times and Threegorge Project will improve ecological restoration，but hasten the soil deposition.This paper put forward the solutions for ecological protection in Honghu Lake: government should strengthen management and legislation system;public awareness and protection activity should be improved;on the premise of the protection priority，natural resources in Honghu Lake can be exploited and utilized rationally；the connection of Honghu Lake and the Yangtze River should be considered and be set into practice in order to achieve the exchange of water and fishes；and research on ecological water requirements for Honghu Lake should be strengthened，and the longterm influence of the Threegorge Project should also be assessed.

On the basis of air quality research for the last five years in the city of Changsha，two air quality statistical forecasting methods were presented in details in this paper，and verification of the two methods was conducted for more than one year.It was revealed that air pollution in Changsha was mainly caused by PM10 and SO2，which exceeded the official permission value.The air pollution showed some degree of spatial distribution.However，changes in the air quality showed a trend towards a better situation over the last five years.The two methods can be used to determinate the forecasting ability for various contaminations.The results showed that the two methods have an accuracy of about 98% for the forecast of NO2；the methods have an obvious effect than the PM10 forecast for the forecast of SO2；and the two methods have similar forecasting results for the three kinds of contaminations.It was indicated that for the two air quality forecasting methods，the forecasting accuracy of NO2 is superior to that of SO2，and the forecasting accuracy of SO2 is superior to that of PM10.

Groundwater is the unique source of drinking water and irrigative water in Karst region. The geochemistry of ground water varies obviously throughout a year. By analyzing the geochemistry of groundwater in Caoshang Karst valley, the authors found that the geochemical property of groundwater exhibited an obvious seasonal change. Some indexes, including specific conductivity, total dissolved solid, and the concentration of SO\-4\+\{2-\} and HCO\-3\+-, were higher in August than those in November. The change was correspondent with the variation of natural conditions because the temperature and precipitation were higher in August than in November in Caoshang Karst valley. Furthermore, the intensity of land use can affect the geochemistry, as anthropogenic activities are normally condensed in August than in November. This paper provides some useful information for understanding the relationship between groundwater and human activity.

The fissure and conduit are well developed and interconnected in karst aquifers due to intensive corrosion, and a “doublelayer structure” has formed in karst areas. The groundwater moves and stores in subterranean fissure, conduit or enlarged underground spaces. There are so many fissures, conduits, swallow holes and shafts in karst areas that the karst aquifer is more sensitive to land use change. It is also the case that the occurrence of complex and deep interconnections between surface and underground in karst areas makes its groundwater particularly liable to contamination. Changes in the hydrology in karst area may thus be a consequence resulted from all other environmental changes in the area. Taking the typical karst subterranean river basin, Houzhai subterranean river basin in Puding County of Guizhou Province, as an example, the intrinsic vulnerability is analyzed in relation to its hydrogeological conditions. Based on more than 20 years′ hydrochemical data, the vulnerability of karst aquifers was analyzed in relation with the land use change, agricultural activity, urbanization and unreasonable human activities. It is shown that the groundwater quality is affected by the land use change, agricultural activity and unreasonable human activity. The content of Ca2+, Mg2+, Cl-, SO2-4, HCO-3 and the total hardness have risen during the last few years, while the content of K+, Na+ fallen. The agricultural activities have caused the rise of nitrate content and mineralization in groundwater and the COD rise is due to unreasonable human activities. It is apparent that the water quality has become worse than before and will be even worse because of the rock desertification and unreasonable land use. Therefore, the unreasonable pattern of land use must be rearranged to protect the karst water resources. It is necessary to carry out ecological rehabilitation or reafforestation, in order to prevent the groundwater from pollution caused by agricultural activities and unreasonable human activities.

As a repository or a source of various contaminants under different conditions, contaminated sediments may pose immediate or potential risk to aquatic organisms. Proper sediments quality criteria (SQC), therefore, are required to indicate the contamination situation. Equilibriumpartitioning approach (EqP) has been intensively studied and incorporated into sediment assessment models in the last few years, and it is believed to be the most promising method to deriving sediment quality criteria. Using EqP approach, this research proposed relative SQC for metals (Cu, Zn, Cd, Pb, Ni, Fe, Hg and As) of the Yangtze River water system. The results of this relative SQC indicated that, in general, SQC declined along the Yangtze River, and it had an obvious area distinction, and most of the heavy metals studied such as Cu, Zn, Cd, Pb, Ni, Hg, As, Fe can be divided into several environment units because of the different environmental geochemistry conditions. The SQC obtained in the present study was comparable with those SQC values already obtained in other areas of China, but was higher than those in USA. As this SQC is only a numeric criterion without the consideration of any biological effects, further research, especially research on toxicity is needed before being used as an integrated assessment of sediments. Furthermore, this research showed the direction of further research and provided a possible way to establish SQC for metals.

The ecosystem service is the support system for us human beings and the whole life system on this planet，and it also refers to the formed qualification and maintained efficacy of the whole ecosystem for us. In this paper，based on cases of the natural and socialeconomic features of the riverhead area of East River and results of Costanza et al.，the methods of ecological economics，welfare economics and ecology were applied to analyze the economic values on the riverhead area of East River. The total value estimated of the ecosystem services is 81×108 yuan，and it is 411 times as the GDP of the riverhead area of East River in 2004. At the same time，the estimated results were analyzed. Through the research，this paper intended to explore the ecological function of riverhead area and its importance in maintaining the ecosystem service functions of the region and the watershed，so as to provide scientific basis for the ecological protection and sustainable use of resources of riverhead area，and also provide references for the research of ecosystem service value of riverhead area.

In this paper，the trend in change of seasonal precipitation and its regional difference in the Tibet Plateau were analyzed for the last 41 years on basis of the longterm precipitation data at 87 meteorological stations in the Plateau.Missing data were interpolated by using Kriging interpolation with the ArcGIS 90.To make the research be complete，annual precipitation in the plateau was also analyzed.The results showed that there is an obvious increase in precipitation during spring and winter，and no such increase in summer and autumn.Decreasing trend of precipitation occurs in the lower reaches of the Yarlung Zangbo River in winter，northeast Tibetan Plateau in spring，central Tibetan Plateau in summer，and west Sichuan Province in summer and autumn.And increasing trend of precipitation appears in the remaining Plateau of decreasing region in winter and spring，south and north Tibetan Plateau in summer，and central and south Tibetan in autumn.It was found that there is an obvious increasing trend for the annual precipitation in the Plateau.There is a boundary at about 102°E in south Tibetan Plateau，with decreasing trend in east of the boundary and increasing trend in the west of it.As the latitude increases，the increasing trend weakens.The annual precipitation showed no obvious trend in central and north Tibetan Plateau.

Based on three group resistance line (TGRL)，and with the aim to decrease the error of the calculation of climate change，which can be significantly influenced by outliers，the variation trends of surface air temperature，extreme temperature and cloudiness in Tibet area from 1971 to 2000 were investigated，and the correlation between temperature and cloudiness change of the area was also analyzed. Compared with the results obtained by traditional least square regression method，the calculations of this study showed that the variation trends revealed by TGRL are less than by the latter，indicating that the traditional least square regression method might overestimate the degree of climate change in Tibet. Increasing trend of minimum temperature is the main factor causing the warming tendency in Tibet，and the warming in spring and summer is much more obvious than that in winter. There is a warming tendency with high (low) values in the west and inner (east) region，where the pattern of tendency distribution shows that localization is affected by the complex terrain. Both of the total and low level cloudiness in the area were decreasing in the past 30 years. It was also shown that variations of temperature have a strong correlation with cloudiness，and decrease in cloudiness is an important reason for the warming in Tibet.