According to the definition of meteorological drought, considering cumulative effect of drought, a daily meteorological drought indicator is presented based on the standardized antecedent precipitation index (SAPI), and the applicability of SAPI were examined by using daily precipitation data of 632 meteorological stations in China from1961 to 2010. SAPI shows a typical “jagged fluctuation pattern” and decreases steadily during rainless periods, thereby overcoming the “unreasonable drought aggravation” problem of the comprehensive meteorological drought index based on equal weight accumulation due to the antecedent precipitation moving out of the calculation window. SAPI is able to describe the processes of occurrence, development and end of drought accurately. Sensitivity analysis show that the needed rainless days to increase one drought level are more in areas or seasons with less rainfall than in those with more rainfall, and the needed daily rainfall to reduce one drought level is less in areas or seasons with less rainfall than in those with more rainfall. In general, drought days of various levels are consistent with their theoretical frequencies. Light and moderate drought days are slightly more in areas or seasons with more rainfall than in those with less rainfall, and the opposite is true for severe and extreme drought days. During 1961-2010, national-averaged drought days of each level all show decreasing trends, among which the trends in extreme drought days are most obvious but with complex spatial-temporal characters. Drought days of each level increase significantly in September-November, however decrease in most of the rest months. Drought days of each level overall decrease in the west but increase in the east of China.

Using daily and hourly station rain gauge data during 1967-2006, the changes in the characteristics of the later-summer (July-August) rainfall intensity over southeast coastal China were analyzed. The results depending on the daily rainfall data confirm that the amount of precipitation in southeastern China has significantly increased, which mainly results from the significant increase of daily precipitation intensity while the frequency does not increase significantly. Based on the hourly rainfall data, it is found the hourly intensity of precipitation and duration time are significantly increased simultaneously in this region. Comparing the average precipitation indices during 1967-1986 with that during 1987-2006. It is found the intensity of short duration (≤4 h) precipitation increases while that of long duration (≥15 h) precipitation decreases and the frequency of long duration precipitation increases. Even so, the average intensity of long duration precipitation is much higher than that of short duration precipitation. In short, the significant increase of the hourly precipitation intensity is resulted from the frequency increase of long duration- and short duration-heavy precipitation and the frequency decrease of short duration-slight precipitation in the past 40 years over the southeastern coast of China.

According to the daily precipitation observation data during 1918-2010 in Tianjin, the long-term tendency of precipitation and extreme precipitation indexes are analyzed. The results show that the annual rainfall and precipitation days have significant interannual fluctuations, but without significant tendencies. The rainfall and precipitation days have displayed a decreasing tendency since 1980, and their variances also become smaller. The rainfall significantly increased in autumn, decreased in summer, and only has small changes in winter and spring. In 1918-2010, all extreme precipitation indexes exhibited no notable linear variation tendency but with large interannual fluctuations. After the1990s, the precipitation intensity was smaller than normal, but showed a slow increasing tendency. The number of heavy rain days was also in a low stage, and its contribution rate to the total precipitation was smaller than normal, and showed a reducing tendency. The maximum rainfall of consecutive 5 days increased significantly in autumn, which reduced the occurrences of autumn drought. The longest consecutive dry days often happened in winter and spring and have increased in recent years.

The spatial-temporal variations of observed temperature based on the 13 stations for 1960-2008 and the 20 stations for 1978-2008 in the Beijing region were analyzed. A rapid decreasing rate of -1.27℃/10a during 1960-1969 , an increasing rate of 0.79℃/10a during 1969-1983 , and a rapid increasing rate of 1.17℃/10a during 1985-1998 are observed by the 13-station temperatures. A slowing-down period from 1998 to 2008 with trends of 0.02℃/10a and -0.05℃/10a are revealed by the 13-station and 20-station observations, respectively. During 1998-2008, warming trend still exists in the urban region. The warming rate in the northern urban region is double of that in the southern part. In the rural area or the stations near a water body or park, decreasing trends are observed during 1998-2008.

Using the 115 tornado events records from 725 stations over China during 1980-2009, geographic and temporal distributive characters of tornado events and reasons for tornado reduction since the 1990s were studied. The results show that tornados frequently occurred in eastern China, and the frequency of tornado events showed a significant decreasing trend in yearly number in 1980-2009, with the highest frequency in the Jul.-Aug. of the 1980s, followed by a distinctly decreasing period, especially in eastern areas. Two important convective parameters, i.e., convective available potential energy (E_CAPE) and vertical shear of 0-6 km wind (S₀₆), in Jul.-Aug. in the period of 1980-2009 were examined to find out reasons for the tornado reduction. The analyses of the centers of E_CAPE , S₀₆, and their products (ES = E_CAPE×S₀₆) suggested that the centers of ES were more coincided with areas of frequent tornados. The significant decreasing in S06 in Jul.-Aug. of 1980-2009 in North China Plain might be responsible for the reduction of tornados in the plain after the 1980s.

Using the forecasts of the five general circulation models distributed by the IPCC, the large-scale environment over the western North Pacific (WNP) under the high (SRES A2) and low (SRES B1) emission scenarios in the 21st century are projected. The results show that the 500 hPa geopotential height over the tropical WNP and the sea surface temperature, especially in the east-central tropic Pacific, both will be above normal. Furthermore, the low-level anomalous anti-cyclonic circulation will cover the region east to the Philippines in the 21st century. Thus the large-scale environment will not be conducive to the formation of tropical cyclones (TCs), and such an environment will be more remarkable under the SRES A2 scenario or after the mid-21st century. The frequency of TC will possibly decline, but the decreasing trend under the SRES B1 scenario will be weaker than that under the SRES A2. There will still be interdecadal and interannual fluctuations of TC frequency in the 21st century.

Based on the meteorological and crop data collected by the 78 meteorological stations in Anhui Province from 1961 to 2009, water demands and precipitation in the field-growth periods of single-cropping rice and winter wheat are discussed. The results indicate that the water demand of single-cropping rice during the field-growth period gradually increased from north to south, but the water supply in most areas of Yanhuai and southen Huaihe valley was sufficient in most years because of the sufficient precipitation. On the contrary, the water demand of winter wheat during the whole-growth period gradually decreased from north to south because of the comprehensive influence of temperature, wind speed and relative humidity in the winter-half-year and the precipitation was also generally insufficient. The water supply could not meet the demand of winter wheat in main production areas, and especially during the key water demand period.

By using the NCEP/NCAR reanalysis data and the station-observed haze days and precipitation data in Jiangsu Province during 1961-2010, decadal variability characteristics of haze days in autumn in recent 50 years were discussed and explained from the influencing aspects of climatological background. Results indicate that the atmospheric circulation and vapor transportation during the low incidence period of haze were in favor of the transfer and dilution of pollutants; and in the high incidence period the haze observably increased, the climatological background field played a more active role in the generation of haze weather compared with the low incidence period. Besides, the frequency of air cleaning reduced remarkably in 1961-2010. SST was closely related to the decadal variability of haze. When the haze days increased continuously, the SST became higher from the Indian Ocean to the South China Sea, giving rise to the convergence/divergence in the low-lever wind field over the sea surface/ the middle latitude area with the same longitude (East Asia) by forming a Hadley-like cell, which is conducive to the formation of haze weather in Jiangsu Province.

Based on the precipitation and water consumption data, and the runoff data observed at Wuzhi hydrological station of the Qinhe River from 1956 to 2000, the trend and abrupt change point of the observed annual runoff series were analyzed and examined using the linear trend and Mann-Kedall methods, and the sliding t-test. The reasons for changes in the observed runoff were analyzed. The linear relationship between accumulated annual precipitation and natural runoff was found for the base period 1956-1972. The amounts of the observed runoff changes caused by precipitation, water consumption and underlying surface changes were isolated. The results show that there is a distinctive decreasing tendency in the observed runoff. The abrupt change year of the annual runoff observed at Wuzhi station is 1972. The observed runoff reduction is caused by the combined effects of rainfall reduction, increase in water consumption, coal mining, and exploitation of groundwater and soil and water conservation measures. The total amount of runoff impacted by increase in water consumption, climate change, and underlying surface change is 70.6 mm, among which 17.6 mm is caused by water consumption, accounting for 24.9%, 35.6 mm caused by climate change, accounting for 50.4%, and 17.5 mm caused by the change of underlying surface, accounting for 24.7%.

The development of biofuel plant cultivation has been widely accepted as an efficient alternative way to ease energy crisis and mitigate climate change. China has released and promulgated a number of laws and policies encouraging the development of renewable energy in recent years. With emphasis and encouragement from the Chinese Government, the cultivation of biofuel plants, such as Jatropha curcas, has been extensively promoted in many areas of China. However, as an emerging industrial cultivation, there are still many uncertainties in the development of biofuel plants. It is important to examine potential problems in order to guide correctly the healthy development of the industry. The impact of industrialization of energy plant cultivation on the biodiversity in important areas is an issue that deserves attention. The possible impacts on biodiversity may include: i) impacts on the actions adopted in the national biodiversity conservation priority areas; ii) impacts on the biodiversity in important areas as well as ecosystem services; iii) impacts of extensive use of exotic species on native species and ecosystems. To address these potential threats to biodiversity, it is recommended that: i) all of the planning and projects for biofuel plant cultivation must obtain approval through strategic environmental assessment or environmental impact assessment, which includes biodiversity elements, before they are implemented; ii) large-scale mono-culture of bioenergy plantations in sensitive biodiversity areas should be avoided, and mixed cultivation of several species, preferably of native species, should be adopted; iii) ecological corridors and ecological infrastructure should be considered when the site for plantation is selected and the cultivation patterns are designed; iv) further studies on the mechanisms of biofuel plant cultivation impacts on biodiversity and on win-win approaches for biodiversity conservation and biofuel development are needed; v) monitoring of the mutual impacts of biofuel development and biodiversity conservation is also needed. Both newly established plantations and existing cultivations should be monitored in order to provide a scientific and practical basis for government’s decision making.