Recently, the droughts attack frequently in the Yangtze River basin, resulting in more and more loss. To further improve regional drought risk management and drought resistance capabilities, it is of great significance to conduct research on the spatio-temporal evolution characteristics of drought in typical drought-prone areas. “Heng-Shao-Lou drought corridor” in Hunan Province is a region with most severe droughts, the standardized precipitation index (SPI) dataset based on monthly precipitation data from 33 meteorological stations in this area from 1971 to 2022 is constructed. Citing the case of Shaoyang County, run theory is applied to integrate drought events, and Gumbel-Copula is adopted to construct the joint distribution function of drought duration and severity, then the joint return periods of drought are calculated and the method is extended to the whole study area. On the basis of it, the classification standard of drought grades is established, and the spatial distribution characteristics of drought probability for each level in the whole study area are analyzed. The results show that the peaks of theoretical joint return period of drought duration and severity for the type Ⅰ and type Ⅱ in Shaoyang County are around 97 a and 27 a, respectively, which indicates that the probability of drought events with long duration and high severity is very small and far lower than that of drought events with long duration or high severity, it is a common feature of drought events in research area. Furthermore, the combination of drought duration and severity joint distribution can effectively avoid segmentation of the whole drought event when drought grades are identified by a single variable, and can evaluate the complexity and large-scale impact of drought more accurately. In the past 52 years, the slight drought occurs most frequently in western region of the “Heng-Shao-Lou drought corridor”, while the frequency of severe or extreme drought is low. Extreme drought mainly distributes in Shaoyang County, Shaodong County and Shuangfeng County.

In order to explore the relationship between natural pasture growth and meteorological conditions under the background of global warming in the ecological function area of northern shore of the Qinghai Lake, the influence of hydrothermal conditions on returning green date, growth height and yield of pasture were analyzed systematically based on meteorological and pasture observation data from 1997 to 2018. The results are as follows: (1) The influence of temperature on returning green date of pasture was significant in northern shore of the Qinghai Lake. The returning green date of pasture had significantly positive correlation with the first day of temperature higher than 0 ℃ and 3 ℃, the correlation coefficients were 0.590 and 0.567, respectively. (2) The growth rate of pasture had significant difference at different stages of growth, and the growth of pasture was the most vigorous from late June to mid-August. (3) The yield of pasture presented a significant ‘ladder’ variation characteristic in northern shore of the Qinghai Lake, and the average yield from 2010 to 2018 was 88% higher than that from 1997 to 2009. (4) The ≥0 ℃ accumulative temperature and precipitation during the growth of pasture presented an increasing trend in northern shore of the Qinghai Lake from 1997 to 2018, while the sunshine duration decreased, the warm and humid change characteristics were obvious, and the accumulative temperature of ≥0 ℃ during the growth of pasture was the key factor for the formation of pasture yield.

Based on the conventional observation data，Doppler radar products and observations of automatic meteorological station，the paper analyzed a heavy hailstorm weather occurred in the south edge of Zhunger Basin on May 2，2010 from weather situation，cloud images change，evolution of physical quantity field and radar echo．The results showed that the hail weather occurred under the weather condition of unstable convective stratification，dry and cold at the middle or upper layer，but humid at the low layer;abundant vapor condition，a  esoscale convergent shear on the ground，the suited height of the 0℃layer and－20℃layer，strong vertical wind shear were all favorable to this weather process．The Doppler radar can properly monitor the developing processe of the hailstone weather．The appearance of＞50 dBZ echo section and cove configuration，convergence region and adverse wind region，increase of VIL value(Vertical Integration of Liquid water)and STI(storm track information)，these all have indication to occurrence of hail weather．

The paper analyzed a hailstone weather occurred in the Zhunger south edge’s region on June 28，2010 based on the routine
data，automatic meteorological station data and CINRAD/CC Doppler radar data．The results showed that the heavy convection weather
occurred under the condition of high altitude trough cooperated with ground cold front and instable atmospheric stratification，dry and cold in middle－high layer and warm and wet in low layer，abundant water vapor，fitting height of 0℃layer and－2．0℃layer，meanwhile there was heavy vertical wind shear．Doppler radar reflectivity factor PPI appeared＞50 dBZ heavy echo section and＞60dBZ heavy echo center．The RHI appeared cove configuration，and the height of＞50 dBZ echo section was more higher than that of 0 ℃layer．The radial velocity map showed mesocyclone，against the wind section．It presented low layer convergence and high layer divergence in hailstone area．Updraft in PPI of different elevations showed circumrotating and rising．Strong echo section corresponded well to against the wind section and mesocyclone，meanwhile VIL，mesocyclone and storm track information products had good indication for hailstone drop．