Along with the rapid development of global tourism, international tourism becomes an important part of international service trade, which is regarded as a significant parameter of internationalization level of a country or a region. In the context of rapid development in national economy, outbound tourism grows rapidly, which proves that international outbound tourism is the inevitable result of continuous global economic growth and international tourism’s rapid globalization. By the propulsion the development of global economy and international trade liberalization, international service trade has become one of the most important ways for the international economic intercourse activities and also has become the developing assistor of the global economy. However, at present, the relationship between the international outbound tourism development and international service trade is still controversial. According to the relevant data of international outbound tourism and international service trade in 1985-2011 in China, the relationship between international outbound tourism and international services trade is analyzed systematically in this ariticle. The results show that: 1) There is a positive correlation between the development of the Chinese international outbound tourism and international service trade. 2) A long-term stable dynamic equilibrium relationship is existed between the development of Chinese international outbound tourism and international service trade. The development of international outbound tourism and the growth of international service trade affect each other, and it has been worked out that the benefits of international service trade to the international outbound tourism are greater than that of international outbound tourism to the international service trade. 3) Short-term fluctuations are existed in the development of Chinese international outbound tourism and international service trade. Whereas, in a given time, these fluctuations could cause retrogression to the long-term equilibrium. Under the influence of the short-term fluctuation in the international tourism, international service trade would suffer a short-term fluctuation. However, international service trade import recovers faster than that of international service trade export to the long-term equilibrium. On the other hand, under the short-term effects of international service trade, international tourism would also have a short-term fluctuation, but international outbound recovers faster than international inbound tourism. 4) The international outbound tourism is in the granger causality with the international services trade exports, while the international outbound tourism is not the granger causality with international services trade imports. The international service trade imports and exports are the granger cause of international outbound tourism. The development of the outbound tourism is conducive to the export of international service trade, but the development of the outbound tourism does not play a significant role in the import of international service trade. The import and export of international service trades are beneficial to the development of outbound tourism. For this reason, China can stimulate the development of international service trade by developing international outbound tourism and hence by loosening the outbound tourism policy in the future.
Tourism industry plays an unnegligible role in the global anthropogenic carbon dioxide (CO2) emission and climate change, with its contribution continuously increase in the future. Tourist transport is the most important activity resulting in CO2 emission in the tourism sector. To develop a low-carbon tourism industry, it is therefore necessary to assess both the patterns and causes of CO2 emission associated with tourist travel. This study selects three tourist destinations in Fujian with an increasing average tourist travel distance, namely Fuzhou National Forest Park (FZ),Taimushan National Key Scenic Spots (TMS), and Wuyishan Scenic Area (WYS), to determine the total amount, intensity, and spatial patterns of CO2 emission from domestic tourist transport. In each tourist destination, a questionnaire survey on tourist travel mode and travel distance was conducted during August to October 2010. Mean CO2 emission from individual tourist of these destinations increased with average travel distance, ranked as FZ (15.9 kg CO2/person) < TMS (105.3 kg CO2/person)<WYS (232.9 kg CO2/person). Though CO2 emission per person-kilometer also increases (FZ, 0.097 kg CO2 /(person·km); TMS, 0.134 kg CO2 /(person·km); WYS, 0.159 kg CO2 /(person·km)), the increase in average travel distance is mainly responsible for the increment of CO2 emission from individual tourist. For each destination, CO2 emission per person·km or per individual tourist within 0-350 km changed little or even declined slightly with increase in travel distance, but increased dramatically beyond 350 km, reflecting the impacts of travel distance on choice of transport mode. Thus, the distance of 350 km can be identified as a threshold for defining the medium- and the long-distance trip based on the transition in CO2 emission with travel distance. The annual total CO2 emission for these destinations rankes as WY (692 899 t)>TMS (65 651 t)>FZ (31 859 t), and the mean CO2 emission density decreases in the sequence of WYS (946.3 t/km), FZ (389.0 t/km) and TMS (166.6 t/km). Depended on both the tourist number and CO2 emission per tourist, CO2 emission density changes with travel distance and differs among destinations, which peaks at 700 km and 1 750 km in WYS, at 250 km and 2250 km in TMS, and at 75 km, 250 km, and 900 km in FZ. The major contribution to total CO2 emission in tourist transport comes from the long-distance and the aerial tourists, which increases with increasing average travel distance. Though tourists with travel distance longer than 350 km occupy only 5.5%, 27.8% and 81.3% of total tourist number respectively in FZ, TMS and WYS, they accounted for 65.1%, 90.0% and 98.7% of total CO2 emission accordingly. The aerial tourists are responsible for 51.3%, 75.4% and 87.8% of total CO2 emission, though they only contribute to 1.5%, 6.29% and 31.1% of total tourist number. Thus, to avoid long-distance or aerial trips is the most important way to cut down the CO2 emission bill associated with travel transport. Efforts that select short-distance trips or trips on more energy-efficient transport should be encouraged.
：Climatic characteristics of snowfall, snow days, snow belt north of 25°N in China is analyzed using the daily snow observation data. The following results have been obtained in the analysis.1) Snow season length and snow days have the feature of latitudinal distribution in the east, with the Da Hinggan Mountains recording the longest (>210 d) snow season, and no snow or only occasional snow all year round in the south of the Yangtze River. In the west, Qinghai Province has the longest (>300 d) snow season, followed by the junction areas of Yunnan, Sichuan and the Tibet. Snow season length in northern Xinjiang is close to the north of Northeast China. The least snowfall occurs in the southeast, and Northeast and northern Northwest record the higher snowfall more (>30 mm),and Qinghai and Tibet are characterized by the highest snowfall(>60 mm). Maximum snowfall intensity is in the Yangtze-Huaihe region. 2) Snow belts are divided based on snowfall frequency: the Northeast and eastern Inner Mongolia, Northern Xinjiang, the Qinghai-Tibet Plateau, and the Qinling Mountains are snow-frequent belts. Southern Yunnan, Sichuan Basin, coastal areas of Jiangsu and Zhejiang and other areas are permanent snow-free belts.The other areas are snow-ordinary belts and snow-occasional belts. 3) The percentage of snowstorm days to total snow days is generally low in all of the regions. The highest percentage is seen for light snow days to total snow days. In view of the ratio of snowfall of all categories to total snowfall, the proportion of snowstorm witnesses the lowest value, followed by heavy snow, and light snow has the highest value in the north of Northeast, North, Northwest, Xinjiang and eastern Tibet Plateau. However, Southeast China is characterized by lowest value of the ratios for light snow, and the highest value for snowstorm. 4) The double-peak distribution of snowfall within the year is seen in northern Northeast, Northwest, Xinjiang and eastern Tibet Plateau, and the Yellow-Huai River basins and Southeast have a single-peak distribution of snowfall. 5) The total snow days, heavy snow days, medium snow days and light snow days generally increase with increasing latitude in the East of China, meanwhile with increasing altitude in the West; with increasing latitude, the total snowfall intensity has a decreasing trend in both the East and the West, also the small snow intensity in the West.
As is well-known, ever since the 1980s, Human Geography in China has achieved comprehensive rehabilitation and it maintains an extraordinary growth speed. Bibliometrics methods is used in this paper to collect statistics of literature which have been published on the three Chinese authoritative geographical journals “Acta Geographica Sinica”, “Scientia Geographica Sinica " and “Geographical Research” from 1980 to 2010. With the object of the articles in Human geography, features of the articles and authors which include the space-time characteristics, research field, methods, and institutes are all analyzed comprehensively. This paper combines the development process and the research hotspot of Human Geography in China and prospects the trend of human geography development in the later period. Results show that Chinese Human Geography emphasizes on the practical applicability and has intensive exchanges as well as intersects with other subjects. What’s more, a mature system of Human Geography authors of the three journals is taking shape. However, there are several shortcomings during the fast improvement, such as the disequilibrium in the development of sub-subjects and distribution of researchers, and lack of guidance theories and innovative methods and models. Only by solving these problems can China’s Human Geography keep a rapid and sound development.
The analysis on intercity relationship and regional spatial structure from the perspective of passenger flow of long-distance coach travel is an important approach to provincial spatial structure studies. Daily passenger flow of long-distance coach travel is a significant part of passenger flow among cities which can reflect functional intercity relationships and reveal the inner-provincial spatial relationship clearly. Based on the daily passenger flow of long-distance coach travel, in this article, Anhui Province is taken as an example. The characteristics of intercity relationships and spatial structure of Anhui Province is explored. To examine the characteristics of intercity relationships and spatial structure of Anhui Province, the research data are analyzed from two aspects. 1) The intensify characteristics of the intercity passenger flow. Passenger flow is graded according to the numerical size, then the passenger characteristics of traffic flow in different regions are analyzed in this article, especially focusing on relationships between the provincial capital (Hefei) and other cities in this province. 2) The structural characteristics of intercity passenger flow. According to directions of the largest passenger flow and the second largest passenger flow, the overall trend and spatial structure of the daily population movements among cities are analyzed, and the provincial nodes in the urban network from the perspective of topological characteristics and the flow strength on the city level are examined in this article. The conclusions are as follows: 1) On the whole, Anhui Province presents a mono-center structure, and the inter-regional links between cities are relatively weak except the center city (Hefei); Hefei affects and maintains frequent contact with Chaohu directly, Lu'an and Huainan. There seems to be a high possibility that these three cities would become a major part of the metropolitan area of Hefei, the economic center and capital of Anhui Province. 2) Wuhu, Ma'anshan, Anqing and Tongling connect with each other tightly, and are the main constitutions of urban belt in Wanjiang, an important carrier of economic development and urbanization in Anhui Province, and further influence Chizhou and Xuancheng. 3）Intercity relations are weak and scattered in the northern region of Anhui Province. The three pairs of cities—Fuyang and Bozhou, Huaibei and Suzhou, Bengbu and Huainan, are important urban groups in the northern Anhui Province. Each of them maintains a close contact within the urban group. And Huainan is the regional hub of northern Anhui Province.
With the prosperity and development of the automotive service industry, as well as the acceleration of urbanization in China, the automotive service industry has become an important part of urban modern service industry, which on turn has an increasing impact in urban space. Taking Nanjing as a case, this paper analyzes and compares the overall spatial agglomeration as well as spatial agglomeration based on sub-industry of automotive service industry. The result indicates that different automotive service industry show different characteristics of spatial agglomeration. Then the overall spatial agglomeration characteristics of automotive service industry were concluded as follows: 1) It shows the characteristics of layer distribution. The five sub-industry, namely car sales industry, auto repair and maintenance industry, auto parts industry, car rental industry and automobile club, agglomerates differently in different layer. 2) In sum, the automotive service industry indicates the feature of small gathering and large dispersion. The overall spatial layout of automotive services industry is relatively fragmented except to several larger gathering areas. 3) Most of the automotive service industries are distributed around the city trunk roads. Thus, it can be concluded that the spatial layout of automotive services is closely related with trunk roads.
In the process of rapid urbanization, the rural labor force pouring into the cities leads to the rising of many social and economic problems in the country. In this study, three typical villages in the central area of Shanxi Province are chosen for empirical research from the perspective of rapid urbanization, especially from the theoretical perspective of the influence of urbanization on rural areas. It is found that the outflow of rural labor force phenomenon is quite prominent. The proportion that peasant households which have migrant workers is over 60%, and there is also a trend that elder migrant worker who has no special skills returns home. In addition, it is also found that there are some other issues in rural areas, such as aging, the low education of children, the woman managing the family alone, the dismantling of traditional rural society, and so on. These problems are inevitable in the process of rapid urbanization.
Information Geography studies the geography of human information dissemination, including spatial distribution rules of information dissemination, spatial structure and its spatial effects, especially the impacts of spatial organization of human societies and economics, as well as the geographical phenomenon induced by virtual reality technologies. Nanjing University embarks on the development of Information Geography systematically with a long history, while deeply rooted in traditional advantageous discipline of geography. Information Geography in Nanjing University produces a wide range of academic influences on five key research areas, i.e. spatial forms in the information era, spatial effects in the information era, digits and the information city, information technology and tourism, residential behaviors and activities in information era and so on. It is prospected that geography and information technology (IT) will be combined deeply in the coming new mobile information era. In the future, it needs to strengthen the empirical researches of Information Geography on the social culture and the humanities further. Five latest trends are also proposed for Information Geography in Nanjing University: 1) Urban space under the deep influences of information technologies, including the new spatial forms of production space, consumption space, social and cultural space, recreation and leisure space under the influence of IT. 2) Behavior geography and mobile IT, including the influences of IT on residences, trips, livings of residents. 3) IT and tourism geography research, including the management of tourism industries, influences on decision-making before tourists’ travel and so on. 4) Smart city and mobile IT, including the transformations of city management and city governance in the mobile IT. 5) Geographical responses to the internet of things, focusing on new empirical studies compared to the concepts of the traditional space, location, spatial interaction, spatial structure and behavioral models.
Due to the advantage differences of tourism resources endowments, geography location, transportation advantage, regional development policies, regional tourism economic development has always great disparities in China. The quantitive characteristics and spatial patterns of the domestic tourism income in 17 cities of Anhui Province in 2000-2010 are taken as an example and analyzed in the article. The evolution features of regional disparity of domestic tourism income in the process of the economic growth are analyzed on the base of the quantitive properties of absolute disparity, relative disparity, degree of regional disparity and spatial patterns from global district to local district of regional spatial centre, polarization patterns, regional disparity patterns, and disparities between the domain pattern of divergence and convergence. The results show that with the growth of domestic tourism economy, the absolute disparity of total tourism income and the sectional tourism income gradually expand. The relative disparity of primary tourism income is overall in the upward trend, and the relative disparity of target tourism income is in the downward trend, and the Gini coefficient is similar to the evolution tendency of coefficient of variation. It is main reason that the unbalanced economic development leads to the disparity expansion of tourism development. Primary tourism cost is the basic indicator reflecting the expenditure people traveling to destinations, and disparity expansion of regional tourism development is reflected firstly in disparity expansion of the primary tourism cost. But with people income increase, tourists will rise the proportion of shopping and entertainment consumption in tourist sites, and as the same time, tourist sites such as shopping and entertainment facilities are newly developed and invested to attract tourists spending. It narrows gradually the disparity of target consumption between original developing tourist sites and the newly developed tourist sites. Therefore, the focus of narrowing the gap of regional domestic tourism income should be placed on reducing the disparity of shopping income of tourist. About the spatial characteristics, the center of domestic tourist economy manifests a southward tendency in Anhui. It mainly attributes to the tourist growth poles of Hefei, Anqing and Huangshan being in the middle Anhui and the southern Anhui. By the analysis on Theil efficient, it can be concluded that the uneven development of tourist income among the northern Anhui, the middle Anhui and the southern Anhui should be considered at first, and the key is to increase the domestic tourist revenue of the northern Anhui. The balance of domestic tourist income of the cities in the middle Anhui is important in narrowing the disparity of tourist income among regions. Especially splitting Chaohu in 2011 will dramatically expand tourism revenue of Hefei, which will continue to expand the disparity of the cities in the middle Anhui. The analysis on the disparity among the cities indicates that Huaibei, Huainan, Suzhou, Fuyang, Bengbu, Lu’an, Maanshan is downward divergent. Their domestic tourist economy is weaker at present and their tourism scale should be expanded.
The response of river water resource to both human activities and climate changes, as the theoretical basis to understand the river hydrological process and the sustainable use of regional water resources, has gained more and more attentions in water research during the last decades. In this study, the seasonal and annual variations and the temporal trend of runoff in Jinqian River Basin were analyzed by using the methods of concentration frequency,concentration period, Kendall coefficient, rescaled range analysis and double mass curve for annual rainfall stream flow comprehensively, in which the runoff and precipitation lagging effect was represented by concentrated period index. The effects of the precipitation change and human activities on runoff were also analyzed quantitatively. The annual runoff of Jinqian River is mainly contributed by those occurred from July to October with a proportion of 65%. Regression analysis showed that the Jinqian River’s runoff decreased with time at a rate of 34.33 m3/（s•10a）significantly (p<0.05). The Hurst index was 0.669, which indicates that the decreasing trends of runoff in Jinqian River’s will continue in the future. There is an around 23.6 days hysteresis in the response of runoff to precipitation, and the hysteresis has obvious up trend. Through the annual runoff coefficient, It was found that the runoff from rainfall decreased with the time due to plant interception, infiltration and evaporation during last 50 years. Human activities and climate change both had significant impacts on the water resource of Jinqian River. The result of double mass analysis showed that the decreases of runoff in Jinqian River’s mainly attributed to climate change, and its contribution were 53.4%.
：In GIS, vector data is the most commonly used data structure. Data compression is an issue in vector data processing and applications. In this paper,several commonly used algorithms of vector data compression are analyzed and a new efficient algorithm is proposed to resolve the problems of the classic algorithms. The Douglas-Peucker algorithm and the vertical distance tolerance algorithm are commonly used algorithms in vector data compression.The Douglas-Peucker algorithm have the advantage that it has invariance in translation and rotation, but at the same time the result has a big area error and there is a contradiction between the compression ratio and retention of feature points for the curvature change. The advantages of the vertical distance tolerance algorithm is fast, but the area error and the characteristics of the retention curve space are very poor. In this paper,a new algorithm is proposed which improved vertical distance tolerance algorithm and resolved the shortcomings of the Douglas-Peucker algorithm and the vertical distance tolerance algorithm.The basic idea of the new algorithm is based on the vertical distance tolerance algorithm which increase an area error tolerance by adopting the method of straight line fitting to approximate the axis of the polyline in order to resolve the problem of the area error and declination of segment in space. An experiment is included, which verified the new algorithm is efficient by the example of dealing with the boundary contour vector of Chongming Island, Shanghai. In the experiment ,the new algorithm has only 1 km2 error, but the classic algorithms has 6 km2 of the error. The most advantage of the new algorithms is that the area error can be controlled in a specified range. The experiments show that comparing with the two classic algorithms,the new algorithm has no substantial advantage in the compression ratio,but greatly improved the performance of two targets, area error and declination of segment in space. It proved that the new algorithm is efficient in the data procession which has high requirement in area accuracy and spatial characteristics such as the use of land resources.
：A field experiment was conducted to investigate the water and salt dynamic of saline-sodic soil with freezing water irrigation in winter in Songnen Plain of China, which is one of the largest saline-sodic areas in the world. The plots were designed as follows: freezing saline water irrigation with application of phosphogypsum (100%GR gypsum requirement) (A), freezing saline water irrigation with application of phosphogypsum (50%GR) (B), freezing fresh water irrigation (C), freezing saline water irrigation (D), no irrigation and no phosphogypsum as CK. A total of 180 mm water was applied to experimental plots in January of 2011. Results showed that melted ice water increased soil water content in topsoil layer. It has great significance for resisting drought in spring planting. With infiltration of melted ice water, the surface soil was significantly desalinized. Major ions including Na+、Cl-、CO32-、HCO3- were decreasing by melted ice water. Comparative analysis demonstrated that desalinized effect was better in freezing saline water irrigation than freezing fresh water irrigation, and desalinized effect was better in freezing saline water irrigation with application of phosphogypsum than freezing saline water irrigation, and with the increase of phosphogypsum, soil desalinized effect was higher. The results indicated that the approach of freezing saline water irrigation and phosphogypsum in winter may benefit to resist drought in spring planting and improve saline-sodic soil by use of local saline groundwater.
SWAT model was used to calculate the agricultural non-point source pollution in Dahuofang reservoir catchment, Liaoning Province. The monitoring data of hydrology and water quality series from 2006 to 2009 was used to calibrate the parameters and validate the model, and the results indicated that SWAT model was appropriate for Dahuofang reservoir catchment. The calibrated model was used to reveal the spatial distribution of agricultural non-point source pollution characteristic. The results show that the annual amount of soil erosion in the reservoir catchment was 1.54×105 t. In other words, there was very light soil erosion in the investigated area. The result was consistent with the actual situation of the forest coverage in this area. The various usage of lands have various degree of soil erosion. The arable lands indicated the highest soil erosion modulus, which were 475.84 t/(km2·a); the open woodlands were the second highest contributor, followed by shrub woodlands, and the soil erosion of the forests were the smallest. The slope output of both nitrogen and phosphorus in catchment were 1 248.83 t and 102.88 t, respectively. The Hun River basin ranked first in the contribution to the load of TN and TP pollution, accounted for 52.01% and 52.43%, respectively, followed by the Suzi River basin and the She River basin. The minimum contributors were the basins around the reservoir. The pollutions of nitrogen and phosphorus were various with different types of land use. The loads of TN and TP were mainly from the arable lands, which were 1 024.33 t and 93.35 t, respectively, which were much higher than the other land use types. Overall, the non-point source pollution around the Hun River basin was higher than the Suzi River′s, while the She River basin was minimum. The output intensity of non-point source pollution of the upstream region was higher than the downstream. This study indicated the spatial spread features of non-point source pollution at target areas, and the results provide a significant support to prevent both soil erosion and non-point source pollution.
The Yellow River Delta is a typical and representative coastal wetland in China. As the Shengli Oil Field, which is the second largest oil field in China, locates in the region, the crude oil contamination has become a key reason which causes deterioration of coastal wetland ecological system in this area. A simulative study was conducted to explain the effects of different concentration of petroleum (0.5%、2.0%) contaminated wetland soils on growth of reed（Phragmites australis）and seepweed (Suaeda salsa) seedling in the greenhouse. The soil samples without oil pollution were collected in coastal wetlands in the Yellow River Delta of soils in May 2010. The soil oil pollution levels was controlled by three oil concentration (0%, 0.5%, 2.0%) in the simulative experiment in greenhouse, four replicates for each treatment. The crude oil in experiments collected from the Shengli Oil Field production wells. The typical representative plants of reed and seepweed in coastal wetlands in the Yellow River Delta were cultivated in the different soil treatments, respectively. The reed was planted with root with same buds and the seepweed seed was sowed (0.5 g per pot). During experiment period, the seedling height of both reed and seepweeed, tillering number of reed, leaf number and branch number of seepweed were recorded. The soluble protein content, Catalase activity (CAT) activities, peroxidase activity (POD) activities, malondialdehyde (MDA) content, Chlorophyll (Chl) content of seedling leaves were determined, then the ratio of chl-a/ chl-b was calculated. The results showed that, with increasing petroleum concentration, the inhibitory effects of petroleum for plant height of reed and seepweed were increased. The inhibitory effects of petroleum contamination on reed tillering number were weakened with time, while that functions on seepweed branch number were strengthened. With increasing oil concentration in soils, the soluble protein content in seedling leaves of seepweed was decline after increase, while the opposite regulars were observed for MDA content and POD activities, and the CAT activities was decreased obviously. Compared to seepweed seedling, the reed seedling appeared high oil contamination tolerance. The Chl content in reed seedling leaves shows a trend of increase after decline with time under different condition of oil contamination. In generally, the inhibitory effects of soil oil contamination for seepweed seedling were higher than that for reed seedling. It indicated that the reed was much more suitable for restoration of oil contaminated soil than seepweed. Our results suggested that both reed and seepweed with high salt-tolerance properties could be extensively applied in soil restoration of oil contamination regions in the coastal wetland of Yellow River Delta.
With the gradually increased flooding on the Hangzhou-Jiaxing-Huzhou plain, this paper analyses the problems involved in the changes of water levels of the hydrological system of this region. As one of the most developed regions in China, the plain is undergoing fierce urbanization process. Based on the daily precipitation and water level data from 1960 to 2007 of Hangzhou-Jiaxing-Huzhou plain, the changes of precipitation and water level time series were analyzed by using linear-regression method, Spearman test, and orderly clustering analysis. Then the contribution rate of precipitation and human activities on water level changes were assessed by normal precipitation years and linear simulation methods. The results showed that the trend of precipitation of regions was no significant, while the water level of the regions was increased. Annual highest, average and lowest water level of the region were increased by 0.03 m/10a,0.05 m/10a and 0.09 m/10a, respectively. And the increase of average and lowest water level of the region reached the significant level. Moreover, the time series of water levels of eight representative hydrologic stations were analyzed. The results showed that most of the water levels of representative hydrologic stations were increased. The trend of all annual lowest water level series was significant, and trend of annual average and highest water level in some stations were significant by Spearman test. In space, along the flow direction, linear trend value of the time series were increased by Kriging interpolation. At last, the reasons for the changes of water level were evaluated. The highest, average and lowest annual water level of the region in normal precipitation years before and after the cut-point were increased by 10.67%, 8.17% and 42.95% respectively, while the precipitation was decreased by -1.06%. The contribution rate of human activities on the changes of the highest, average and lowest water level ??were 39.0%, 56.2% and 82.9% respectively. Human activities were the important cause to water level changes, particularly, to annual lowest water level. The results of this paper will be helpful for the water resources management of the urbanizing plain river network region and sustainable development of society and economy under the changing environment.
Based on the daily NECP /NCAR reanalysis data of 500 hPa height field from 1948 to 2009, an objective classification and widely-agreed method was applied to analyze the temporal and spatial distributions of atmospheric blockings high in Asia during summer,In addition, the location and numbers of blockings high was automatically determined. The results show that there are 1 337 blocking events during the last 62 summers. According to the active period of blocking events, a period of 3-7 days are dominant during all the events which account for 80.1%. Based on the accumulative numbers and days, the blockings are divided into eastward type (blocking high over the Okhotsk Sea), westward type (blocking high over Ural Mountain), central type (blocking high over Baikal Lake) and the others, totally four types, occupying at 27.5%, 30.4%, 18.3%, and 23.8 %, respectively. Since 1990s, blocking events in Ural region are in a weak period, otherwise in Okhotsk region are in a strong period ,but blocking events in Ural region begin taking upward trend at the beginning of 21st century. Bblockings in Okhotsk region take a clear downward trend. There is a significant positive relationship between blocking events and cold vortex in Northeast China, but a negative correlation between blocking events and temperature of Changchun and Harbin in summer. Blocking high is one of important circulation system which causes the low temperature in Northeast of China in summer. During westward type blocking events strongly active years in June, a strong easterlies air flow in 850 hPa is found over the region of 20°E -140°E, 40°N -55°N, It is advantageous for cold air come from the northeast path in Okhotsk region to invade Northeast Asia and the northeast area in China.
By using precipitation data of 200 stations in the winter half Year (from October to next May) in Northeast China and NCEP / NCAR temperature reanalysis data with a horizontal resolution of 2.5o×2.5o, a classification of snowstorm events in Northeast China is proposed based on phase features of water content in the precipitation . The snowstorm events can be grouped into two categories: one with only pure snowfall (Type I ) and the other with snow and rain mix ( Type II ). And each type can be further classified into three groups, namely, extensive, regional and local range according to the area affected. On this base, the spatial and temporal characteristics of different types of snowstorms in Northeast China are studied. It is showed that the two types bear basiclly the samef requency of occurrence, however, with respect to extensive-range events,the type II is much more frequent than the typeⅠ, while for local snowstorms the situation is reversed. There are substantial interannual variations of the snowstorm events in Northeast China , and the interdecadal characteristics are also obvious. The frequency of type Ⅰwas significantly higher than type Ⅱ during the late 1970’s to the mid 1980’s, and the reverse appeared in the beginning of 2000’s, which might imply the response of climate in Northeast China to the global warming. Snowstorms in Northeast China mainly occur in late autumn and early spring, but the timing of their beginning, ending and peak of activity are different for the two types . The frequency of snowstorm decreases from the west to the east for both types, but the decrease is even sharper from the northwest to southeast for the type II events. The results suggest the classification approach proposed well reflects the difference of two types of snowstorm process in Northest China in terms of their spatio-temporal variations . The results are also in agreement with previous case studies ,which may justify, to some extent, the rationality of the method proposed, and its usefulness for the coming practical works.
By use of the precipitation data from hydrological station at Fengman basin in 1936-2008, as well as the reanalysis data from National Center for Environmental Prediction (NCEP) in 1948-2008, the characteristics associated with the precipitation variation in flood season at this basin were discussed by means of linear trend analysis, wavelet analysis, M-K analysis and maximum entropy spectrum analysis. The results show that, both the total amounts of precipitation at flood season and the whole year are decreased with time in Fengman basin, especially in the recent 20 and 30 years. The precipitation at flood season decreases more than the annual precipitation, for the precipitation decrease trend values in flood season reach -39.2 mm/10a from 1989 to 2008, but those of annual precipitation are only -26.5 mm/10a from 1979 to 2008. The total amounts of precipitation decrease sharply in August and September, while little in June and July during flood season. Results from analysis of maximum entropy spectrum and Morlet wavelet show that, there are two kinds of precipitation cycles in flood season at Fengman basin. One is the relative short cycle with eight to nine years, the other is the long cycle with twenty eight years. In order to study the possible reasons about the decrease trend in flood season at Fengman basin, the circulation fields in 200 hPa and 700 hPa, and the wind fields in 850 hPa were analyzed by use of the NCEP data from 1948 to 2008. It shows that, the main reasons about the decrease trend in flood season at Fengman basin are the co-effects of the reduced amounts of Typhoon and the days of cold vortex in Northeast of China affecting this basin, as well as the unfavorable condition for water vapor conveying northwards as the subtropical high is more southerly and westerly than usual, and the northward movement of the weather systems on the south.
