Based on the same term observations of extreme temperature data during 1961-2000 in China, we have evaluated seven model's output product including frost days (FD), growing season length (GSL), extreme temperature range (ETR), warm nights (TN90), and heat wave duration index (HDWI) supplied by the IPCC-AR4. The results show that all the models have the capability of modeling temperature characteristics in spatial and temporal variations and there are systematic errors in each model. This result indicates that the models' simulation accuracies for the five temperature indices are in the order from the best to the worst: FD, TN90, HWDI, ETR and GSL. In terms of the spatial distribution, the bad modeling effect is TN90, the characteristic distributions of other extreme temperature indices can be modeled. Generally, GFDL-CM2.0 and MIROC3.2 (hires) can best model the extreme temperature indices in China.
Based on the daily highest temperature data covering the period 1961-2005, temporal and spatial characteristics and their changing in mean annual and monthly high temperature days (HTDs) and the mean daily highest temperature (MDHT) during annual and monthly HTDs in East China were studied. The results show that the mean annual HTDs were 15.1 and the MDHT during annual HTDs was 36.3 oC in the past 45 years. Both the mean annual HTDs and the MDHT during annual HTDs were negative anomaly in the 1980s and positive anomaly in the other periods of time, oscillating with a cycle of about 12-15 years. The mean annual HTDs were more in the southern part, but less in the northern part of East China. The MDHT during annual HTDs was higher in Zhejiang, Anhui and Jiangxi provinces in the central and western parts of East China. The high temperature process (HTP) was more in the southwestern part, but less in the northeastern part of East China. Both the numbers of HTDs and HTP were most in July, and the MDHT during monthly HTDs was also the highest in July. In the first 5 years of the 21st century, the mean annual HTDs and the MDHT during annual HTDs increased at most of the stations, both the mean monthly HTDs and the MDHT during monthly HTDs were positive anomaly from April to October, the number of each type of HTP generally was the most and the MDHT in each type of HTP was also the highest.
The urban thermal environment effect resulted from urban heat island phenomena becomes prominent with the rapid urban expansion, which had adverse effect on the urban environment and the urban sustainable development. Spatial-temporal change of urban thermal environment is relevant to interactions of human activities such as the change of underlying surface, anthropogenic heat emission and environmental pollution. Due to the complexity of factors contributing to urban thermal environment, the routine observing methods and statistical methods are insufficient in acquiring data and analyzing the responses of human activities to thermal environment, especially discerning the major attributors from the others. Fortunately, the remote sensing and GIS can resolve the technical problem effectively, which can quantitatively explore the relationship of spatial-temporal change of thermal environment with human activities. Based on Landsat ETM+ images and taking the urban area inside the ring road of Shanghai as a case study, this paper employed Spatial Principal Component Analysis (PCA) method to analyze the spatial pattern and the influencing factors of urban thermal environment as a substitute of Multi-Criterion Evaluation (MCE) method. The results showed that urban construction density and population density, allocation of industries, types of underlying surface and diversity of urban landscape were the leading factors contributing to the urban thermal environment in the metropolitan area of Shanghai. The linear model including the four independent variables could reveal the response mechanism of human activities on thermal environment in Shanghai. From the model, urban building density and population aggregation were regarded as the most sensitive factors to thermal environment among these factors. Furthermore, the difference in spatial distributions of the main factors formation of the diverse urban thermal environment in different areas. The results would be of value to simulate spatial change of urban thermal environment and even put forward countermeasures to lessen the urban thermal environment intensity for policy makers.
Based on climatic data of 8 stations in the Qilian Mt. region, methods of regression analysis and moving average were used to study the climatic changing trend of the study area under the background of global warming. Results showed that the temperature increased after the mid-1980s and climatic warming has accelerated since the 1990s due to the rise of temperature in autumn and winter. The precipitation experienced a changing trend, that is lower (the 1960s)--higher (the 1980s)--lower (the 1990s)--higher (after 2000). The regional difference in temperature rise is, with the main Heihe River as the divide, characterized by the fact that it is increasing from south to north in the middle-eastern Qilian Mt. region while decreasing from south to north in the middle-western. Also the precipitation presents obvious spatial change. The rising range is decreasing from east to west in the eastern Qilian Mt. region, while decreasing from south to north in the western. What's more, methods of T checking, Cramer and Mann-Kendall were employed to analyze climatic break, indicating that the abrupt change of temperature was more noticeable than that of precipitation in the study area. The abrupt change of spring and summer temperature happened in 1997 while that of autumn and winter appeared in 1985. Moreover, the temperature abrupt change in 1987 was more obvious than in 1997 because the scale of temperature rise was higher in autumn and winter than in spring and summer, and the precipitation break in the eastern, middle and western regions happened in 1980, 1972 and 1969, respectively.
The features and the development law of rhyolite landforms are unique. Based on the survey and analysis data, the paper has analyzed the types, the distribution and the development of the rhyolite landforms in Yandang Mt. The study results show that the landforms in this region can be divided into two types, six sub-types and sixteen type units. The peaks, cliffs and waterfalls are all distributed vertically at different heights, and the valleys and line-cliffs extend along the faults with strikes of NE, NW and EW horizontally. The development of the landforms in the region has experienced four stages in which there developed different kinds of landforms. The study in the paper can contribute to the building of this World Geopark and flourish the local tourism.
Sporo-pollen records from the western part of Chinese Loess Plateau revealed a detailed history of vegetation variation and associated climate changes since 13 ka BP. Before 12.1 ka BP, steppe or desert-steppe vegetation dominated landscape, which was then replaced by a coniferous forest under a generally wet climate (12.1-11.0 ka BP). The vegetation was degenerated into steppe landscape and further into a desert-steppe landscape from 11.0 to 9.8 ka BP. After a brief episode of a cool and wet climate (9.8-9.6 ka BP), a relatively mild and dry condition prevailed during the early Holocene (9.6-7.6 ka BP). The most favourable climate of warm and humid period occurred during mid-Holocene (7.6-4.0 ka BP) marked by forest-steppe landscape, and an alternation of steppe and desert-steppe has occurred since ~4.0 ka BP.
According to field investigations and sampling as well as laboratory analysis of magnetic susceptibility, grain size, optically stimulated luminescence (OSL) and AMS 14C dating of archaeological site profile of Shangshan in Pujiang area, Zhejiang, this paper revealed the process of environmental change since Mid-Pleistocene and discussed the background of Shangshan cultural development. The results show there were fluvial gravel sediments in Shangshan area in the earlier period of Mid-Pleistocene. But at about 173 ka BP of the late period of Mid-Pleistocene, uplift happened in Shangshan area because of the impact of the climate, sea level change and neotectonic action, movement, thus forming the second terrace of the river. Between 173-75 ka BP, the terrace received aeolian sediment, a layer of reticulate laterite about 80-100 cm thick deposited, and developed under a relatively high temperature. A layer of Xiashu Loess about 1.0-1.5 m thick deposited on Shangshan terrace in late glacial, containing 80% of the loessal dust. At the beginning of the Holocene (11500 a BP-), temperature went higher gradually with more precipitation, the pre-historic human moved on the Shangshan terrace (11400-8600 a BP), which may connect the paleolithic culture and Neolithic culture. The lower place to the west of the Shangshan Site has been the two cycles process of the fluvial facies, lake and moor facies, indicating that the water source of the Shangshan pre-history is the river water or lake water. Moreover, two AMS 14C ages indicated the water resource disappeared more than 1000 years at most.
China is now at a rapid urbanization stage, and various measures are needed including land use regulation to ensure healthy urbanization process. Based on land use change survey data of the Ministry of Land and Resources, this paper analyzes status of town-level land use at the stage of rapid urbanization of China, from aspects of town-level land quantity, town land area per person, land occupied by town construction, land use structure of town, spatial pattern of town-level land, and their spatio-temporal changes. It then identifies major town-level land use problems of this stage as town-level land scale being out of control, extensive land utilization, affected macroscopic economic development, affected cultivated land protection and food security, menaced social harmonious development, misadjusted land use structure, and deteriorated eco-environment. It finally explores scientific land use strategy for healthy urbanization, from the angles of rational guiding town expansion and rigidly reinforcing agriculture land protection, optimizing regional and town-level land use structure and distribution, frugally and intensively utilizing town-level land with various measures, giving overall consideration and coordinating regional urban and rural residential built-up land, and promoting benign town-level land eco-environment through simultaneous adoption of prevention and control measures.
The paper quantifies cultivated land resources economic value, social insurance value and ecological service value in Beijing from 1990 to 2005. The results indicate that: (1) The economic value per hectare increased rapidly from 12.57×104 yuan in 1990 to 108.12× 104 yuan in 2005. (2) In Beijing region, the social insurance value supplied by cultivated land resources is low, but the demand for the social insurance value of the rural residents is high. The supply is 49.19 ×104 yuan/hm2 in 1997 and 74.82 ×104 yuan/hm2 in 2005, while the demand is 160.56 ×104 yuan/hm2 in 1990 and 305.48 ×104 yuan/hm2 in 2005. As the most important basic resources for rural population, cultivated land resources have been overexploited, thus the rural social insurance system should be established as soon as possible, shifting land insurance function out. (3) The total ecological service value went up at first, then decreased greatly, being 142.75 ×108 yuan in 1990, 171.21 ×108 yuan in 1994 and 70.87 ×108 yuan in 2005, respectively, which is due to the decrease of cultivated land resources in Beijing region. But the total ecological service value demand and diversification demand increased because of population growth and living standard raising. In order to keep and improve the vegetation cover, the government should make some ecological compensation for the rural residents. Finally, the paper puts forward that in order to preserve cultivated land resources, the interests of every value subject need to be taken into account, especially the farmers' interest, and that the three values of cultivated land resources would be coordinated.
