Heilongjiang Province is the major grain production base in China, the study of drought climate characteristics in Heilongjiang Province is of great importance for scientific prevention and management of drought disasters. Based on daily temperature and precipitation data from 80 national meteorological stations in Heilongjiang Province from May to September during 1971-2020, the daily meteorological drought composite index (MCI) of Heilongjiang Province was calculated, and the spatial and temporal distribution characteristics of drought, severe drought and extreme drought days in Heilongjiang Province were analyzed. At the same time, the circulation characteristics of typical dry and wet years were further analyzed. The results show that from May to September during 1971-2020, the southern part of the Greater Hinggan Mountains and the western part of Songnen Plain in Heilongjiang Province are drought-prone areas. The number of dry days is more in the west and some areas of the central hinterland and less in the east. The inter-decadal characteristics of medium drought, severe drought and extreme drought are obvious and show a decreasing trend. The decreasing trend of medium drought was the most obvious with a rate of -1.7 d·(10 a)^-1. There are significant differences in circulation patterns between typical dry years and wet years. In typical dry years, the area west of Lake Baikal is controlled by anticyclones, while Heilongjiang is controlled by the westerly jet stream, resulting in prevailing descending airflow, which is not conducive to the intersection of cold and warm air, and the water vapor transport channel is not obvious, so water vapor is difficult to reach the Heilongjiang region. Conversely, in typical wet years, the situation is the opposite.

The convective weather and lightning disasters occurred frequently in the northeastern verge of Tibetan Plateau. In order to analyze the characteristics of cloud-to-ground (CG) lightning flashes, the CG location data and daily precipitation collected by the advanced toa and direction （ADTD） system of Gansu Provincial Meteorological Administration and CIMISS during 2017-2020 are used to investigate the spatial and temporal characteristics of the CG lightning frequency, current intensity and the CG flashes density in the northeastern verge of Tibetan Plateau, and the relationship between the CG flashes density and precipitation. The results show that the annual average number of the CG lightning in this region in recent four years was about 2.71×10⁴ times. The annual average negative CG and positive CG lightning accounted for 84.27% and 15.73% of the total CG lightning flashes, respectively. The monthly distribution of the CG lightning flashes presented a single-peak pattern. Specifically, the CG lighting flashes mainly occurred in summer, which accounted for 70.11% of the CG lightning in the whole year. In spring and autumn, the percentage of the CG lightning was less than that in summer, and in winter the number was least. The diurnal distribution of the CG lightning frequency also showed a single peak. The peak value of the total CG and negative CG lightning occurred mainly from 10:00 BST to 12:00 BST in a day. The occurring time of peak value for positive CG lightning lagged one hour than the negative CG lightning. Although the number of monthly-averaged positive CG lightning was much less than that of negative CG lightning from April to October, the ratio of average current intensity of positive CG lightning flashes to that of negative CG flash was 1.56. The CG lightning flashes density greater than 0.24 fl·km^-2·a^-1 concentrated in Yongdeng County of Lanzhou, Luqu County, Maqu County and Hezuo City in Gannan Tibetan Autonomous Prefecture, Zhangjiachuan County in Tianshui City, Huachi County, Huan County, Zhenyuan County and Qingcheng County in Qingyang City, Wen County and the south of Longnan City. And the high incidence areas of positive CG lightning mainly occurred in Maqu County, Luqu County, the junction of Dingxi City and Gannan Tibetan Autonomous, and the central and southern part of Qingyang City. Lighting protection measures should be strengthened in the above areas. By comparing the density of the CG lightning and precipitation, it is found that the spatial and temporal distributions of lightning activity was consistent with precipitation in the northeastern verge of Tibetan Plateau.

Drought is one of the natural disasters with the widest impact and the most serious economic losses in China, which directly threatens the country’s food security and socio-economic development. The understanding and research on drought will help to improve the national capacity of drought prevention and mitigation. Since 1949, China’s research on drought meteorology has achieved fruitful results. Based on the research results of the scientific research project group related to drought meteorology carried out by the Key Open Laboratory of Arid Climate Change and Disaster Reduction of China Meteorological Administration since the 21st century, through the achievement retrieval, this paper summarizes the new progress in drought monitoring technology, drought temporal and spatial distribution, drought disaster-causing characteristics, drought disaster risk and its response to climate warming, as well as drought disaster risk management and defense technology. At the same time, based on the frontier development trend of drought meteorology research, on the basis of strengthening the comprehensive drought observation test in drought prone areas under the background of climate change, this paper puts forward that China’s drought meteorology research in future should study quantitatively the formation mechanism of drought from different dimensions and scales, build a new comprehensive drought monitoring method of multi-source data fusion and multi-method combination, reveal the mechanism of drought disaster-causing and evaluate scientifically the drought disaster risk, putting forward the executable risk management strategies. This work is of positive significance to promoting drought meteorological research in China.

Grassland is the main ecosystem of the Korqin area, and the quantitative study of its surface evapotranspiration is of great significance to master the ecological effect of the Korqin grassland. Based on surface evapotranspiration dataset of MOD16 and meteorological observation data from 2000 to 2019, the temporal and spatial variation characteristics of surface evapotranspiration and its meteorological influencing factors in the Korqin grassland were analyzed. The results are as follows: (1) MOD16 products have good applicability in the Korqin grassland, and the determination coefficient between surface potential evapotranspiration of MOD16 products (MOD16-PET) and evaporation of evaporating pan was above 0.9. (2) The monthly distribution of MOD16-ET and MOD16-PET presented a typical single-peak pattern in the Korqin grassland, and their evapotranspiration increased at first and then decreased. The inter-annual change of MOD16-ET was obvious than MOD16-PET in the Korqin grassland from 2000 to 2019. MOD16-ET increased significantly with 28.86 mm·(10 a)^-1 rate, and the increasing area was more than 75%, while MOD16-PET decreased significantly with a rate of 13.35 mm·(10 a)^-1 as a whole, and the increasing area was greater than the reducing area. (3) The high values of ET distributed in the northwest of the Korqin grassland, while that of PET distributed in the central region, and they had a reverse spatial differentiation characteristics to some extent. The surface evapotranspiration was different under different types of land use, and ET reduced from woodland, grassland and farmland in turn, while PET was opposite. (4) The mutation of ET from weak to strong occurred in 2003 and 2011, respectively, while that of PET from strong to weak occurred in 2015 in the Korqin grassland from 2000 to 2019, and ET in about 20% region would be likely to continue the current trend in the future. (5) The correlations of ET and PET with meteorological factors were consistent, and they were significantly and positively correlated with precipitation and sunshine hours, while their correlations weren’t obvious with temperature, relative humidity and wind speed.

Multi-time scale characteristics of ventilation quantity, mixed layer height, atmospheric stability and mean wind speed in mixed layer in Chongqing main city zone were quantitatively analyzed using the recent 30-year data observed at Shapingba meteorological station in Chonqing. The ventilation quantity in Chongqing main city zone exhibited evident decadal variations, and it lay in a high level and showed a descending trend before 2003, while it lay in a low level after 2003 and showed an ascending trend in recent 10 years. The decadal changes of ventilation quantity in four seasons were consistent with that of the annual mean. The ventilation quantity had an oscillation period from 2 to 3 years. In different seasons, the inter-annual oscillation intensity varied with the largest oscillation amplitude in summer and a relatively smaller one in autumn and winter. The ventilation quantity was significantly correlated with mixed layer height and mean wind speed in mixed layer. The seasonal difference of ventilation quantity was obvious with the largest value in summer and the smallest value in winter. The diurnal variation of ventilation quantity was basically consistent with mixing height and mean wind speed in mixed layer, which reached its maximum in the afternoon and could last until the evening.

Adequate understanding of water stress influences on the temporal-spatial variations of soil moisture is crucial for studying water consumption and drought identification in grasslands. Based on soil volumetric water content data monitored in multi-layer soil under two water supply conditions during 2016-2017, soil water status, the seasonal variations and the vertical distribution in the typical steppe in Xilinhot of Inner Mongolia were investigated. The results show that soil water showed distinct seasonal variations in a normal year with dual peaks curve. That was, soil volumetric water content reached the peak in the spring green-up and the rainy season (July), and then it decreased and reached the minimum value in the late of May and the early of September. Soil water content of top 50 cm layer also exhibited marked variation, especially for 0-30 cm layer. The water stress changed the seasonal dynamics of soil moisture (i.e. reduction in the amplitude). More importantly, serious water stress caused that the dual peaks curve failed (becoming smooth), and the water consumption happened in the deeper layer. Moreover, the sensitive area of soil water change extended to the 60-80 cm soil layer. The results highlight that seasonal variations in soil moisture and soil depth are two valuable factors analyzing the interactions between water stress and ecosystem as well as soil drought index.

Based on the data of 64 meteorological stations from 1971 to 2017 in Karst region of Guangxi Zhuang Autonomous Region, standardized precipitation evapotranspiration index (SPEI) was adopted as a drought evaluation index to analyze the spatial-temporal evolution rules of drought in this region. The results show that in the study area, the annual droughts generally occurred once every two years and their frequency increased from the middle part to the east and west, which were mainly light drought or moderate drought. By contrast, the seasonal drought was mainly concentrated in autumn, followed by winter drought, with low frequency of spring drought and summer drought. Besides, spring drought occurred every 3 to 4 years, and the frequency decreased from southwest to northeast. Summer drought also appeared every 3 to 4 years, but its frequency showed a weakening trend from east to west. The autumn drought occurred almost every year and its frequency was higher in central and eastern part than that in western part, with more severe drought and extreme drought than other seasons. The frequency of winter drought was similar to the autumn drought, but it was higher in the northwest and decreased from west to east. From 1971 to 2017, the winter drought and summer drought of studying area showed a fluctuating and weakening trend, while the spring drought and autumn drought showed an increasing trend. On the time scale of 15 to 20 years, there was an obvious dry-wet cycle in annual and seasonal drought, and the drought cycle below 5 years oscillated more frequently. The significant positive correlation between SPEI and soil moisture made it possible to use SPEI objectively to reflect the drought situation in the region.

Considering the different disaster-pregnant environment, population density and economic condition, the drought disaster chain models in southwest and south China were constructed respectively by using history data and record of references. Here, the disaster-pregnant environment includes climate background, underlying surface, landforms, soil and river network. And on this basis that the transmission characteristics of disaster on separate disaster chains were analyzed. The results show that the drought disaster chain structure is similar in southwest and south China, but their transfer process of disaster on the two chain is different. There are obvious regional characteristics of disaster transfer on their chain. The incipient drought can cause crop drought in southwest China, while moderate drought can cause crop drought in south China. In southwest China, the moderate drought can lead to some problems such as people and livestock drinking water difficult and livestock forage shortage, but these corresponding problems can be generated by the severe drought in south China. Being the difference in disaster-pregnant environment, the rock desertification phenomenon appears in southwest China under the severe drought condition, but the probability of rock desertification is small in south China except for north Guangxi. In the same region, as far as the various disaster-affected bodies are concerned, the threshold of drought degree transmitting is different. For example, shipping problems usually result from the moderate drought, and forest fire and pest disaster are often led by the severe drought, while soil degradations appear in the extreme drought.