Soil temperature reflects the thermal state of soil and plays a crucial role in the exchange of surface energy, and it directly influences the water and heat redistribution of soil. In alpine mountainous area, the hydrological and energy transfers are more special and complex. Therefore, it is essential to simulate accurately soil temperature in investigating hydrological cycles in alpine mountainous areas. CLM 5.0 (Community Land Model 5.0) is the latest version of the CLM model, which is one of the most advanced land surface process models in the world. In this paper, the soil temperature simulation performance of CLM 5.0 is evaluated based on the measured data of 9 typical observation stations in the upper reaches of the Heihe River Basin. The results are as follows: (1) CLM 5.0 can well simulate the annual and inter-annual changes of soil temperature in alpine mountainous areas, but the simulated values are generally underestimated. (2) The simulation performance of CLM 5.0 on soil temperature in alpine meadow is slightly higher than that in grassland, and it in shallow soil layers is better than in deep soil layers. (3) CLM 5.0 exhibits greater underestimation to soil temperature in the non-growth period than in the growth period, and greater underestimation under frozen state than under unfrozen state. (4) The underestimation of CLM 5.0 simulated soil temperature in the non-growth period is mainly due to the underestimation of soil temperature under frozen state, which results from errors in estimating soil ice. These results provide insights for future applications and improvements of CLM 5.0 in alpine mountainous areas.

The heterogeneity of precipitation in space and time can easily lead to the formation of drought and flood disasters. Under the background of global warming, there are significant regional differences in spatio-temporal distribution patterns of precipitation. It is of great significance for food security, flood control and drought relief to explore the heterogeneity characteristics of regional precipitation. Based on the daily precipitation observation data of Heilongjiang Province in summer from 1951 to 2020, the common calculation methods of precipitation concentration period (PCP) and precipitation concentration degree (PCD) are contrastively screened, firstly. Then, combined with correlation analysis, trend analysis and wavelet analysis, the characteristics of summer precipitation non-uniformity and its influencing factors are explored in Heilongjiang Province. The results show that the Heilongjiang summer PCP is earlier in the southwest and later in the northeast, and the earliest PCP is in the hinterland of the Songnen Plain (July 6 to 20), the latest PCP is in the hinterland of the Sanjiang Plain (August 10 to 25). The summer PCD is larger in the west and smaller in the north-central, northwest and southeast edge, the smallest PCD is in the transition zone between the Lesser Khingan Mountains and the Sanjiang Plain, and the largest PCD is in the hinterland of the Songnen Plain. When the summer PCP is early, the summer PCD tends to be large, which indicates that the summer precipitation in the areas with early heavy precipitation tends to be more in the early stage and less in the late stage. The inter-annual scale oscillation with a period of 2.0-4.0 a of summer PCP and PCD in Heilongjiang Province is obvious, and there is non-significant change trend on the whole. The summer PCP and PCD are significantly affected by the atmospheric circulation and sea temperature in the early period and the same period. On the whole, the summer PCP is significantly positively correlated with the North American polar vortex area index in May, while it is significantly negatively correlated with the western Pacific 850 hPa trade wind index in May and the Scandinavia teleconnection pattern index in August. The summer PCD is significantly positively correlated with the central Pacific 850 hPa trade wind index in summer, while it is significantly negatively with the North African-North Atlantic-North American subtropical high ridge position index in June and the eastern Pacific ENSO index in July, but the significant correlation regions for different climate indexes were different.

Based on European Centre for Medium-Range Weather Forecasts （ECMWF） fifth-generation global atmospheric reanalysis （ERA5） every day from May to August during 1979-2020, three land-atmosphere indexes to investigate land-atmosphere coupling processes were calculated,characteristics of land-atmosphere coupling in climatology and their difference under different dry and wetsoil conditions were analyzed over eastern and southern Asia. The results show that Northeast and North China,the Tibetan plateau, India, Yunnan Province of China and Southeast Asia,the middle latitude arid zone were strong land-atmosphere coupling zones in climatology. In the middle latitude arid zone, land-atmosphere coupling had no significant difference under different soil conditions due to the low soil moisture and its little variability. In the other strong coupling zones, the coupling strength decreased with increasing soil moisture condition because of the bigger variability of soil moisture in these regions, and this law is applicable to the coupling processes between soil moisture（SM） and evapotranspiration （ET）, between ET and water vapor condition of boundary layer, between ET and instability condition of boundary layer. The land-atmosphere couplings over South China were weak in climatology, coupling between SM and ET was significant only under dry soil conditions, while the coupling between ET and atmospheric boundary layer were not significant under all soil moisture conditions.

According to “the Regulations on Monitoring and Evaluation of Regional Important Processes” issued by China Meteorological Administration in 2019, the basic situations of China’s climate and main meteorological disasters in summer 2021 are comprehensively analyzed based on the meteorological observation data of more than 2400 ground stations in China from 1961 to 2021. The results are as follows: (1) In the summer of 2021, both the average temperature and the average precipitation were higher than that in the same period of the previous years. The rainy season in the north started earlier with enhanced intensity, while it delayed in the south with weakened intensity. These two factors, together with the decreased number of landing typhoons, contributed to the fact that the summer precipitation zones dominated North China. (2) In the summer of 2021, China’s climate conditions were generally worse than normal, the situation of meteorological disasters was complicated and severe, accompanied with frequent occurrences of extreme weather and climate composite events, including flood, heat wave and drought, and moreover, the disasters exhibited periodic and regional features. The number of regional rainstorm processes was 4.9 times lower than that in previous summers, but the extremeness was much stronger. North China, Huanghuai, Jianghan and other places have suffered from severe rainstorms and floods consecutively. Regional high temperature occurred frequently and periodically. The number of regional high temperature processes was 3.4 times higher than that in previous summers, which mainly impacted Huanghai, Jiangnan, South China, the east of Northwest China, the west of Inner Mongolia and the south of Xinjiang. Meteorological droughts appeared in the south and the north simultaneously, with significant regional, periodic and compounding characteristics. And the number of regional drought processes was 1.1 times higher than that in previous summers. South China and Northwest China witnessed the compound development of high temperature and drought.

Based on wire icing observation data at 18 icing meteorological stations and conventional meteorological observation data at 91 meteorological stations of Shanxi Province, the meteorological estimation model of designed wire icing thickness was built by using stepwise regression analysis in different climatic regions, respectively. Then, the designed wire icing thickness at each station under 30-year, 50-year and 100-year return periods was estimated by regression models. And on this basis, combined with DEM data and wire icing observation data in the process of power grid operation and maintenance, the designed wire icing thickness was corrected by terrain, and it in easily icing areas was modified according to operating experience of power grid, the spatial distribution and division of wire icing thickness were obtained in Shanxi Province. The results are as follows: (1) The designed wire icing thickness in Shanxi Province was closely related to air temperature, relative humidity, wind speed and water vapor pressure, it was also related to precipitation and sunshine duration in alpine region, and the influence of meteorological conditions on continuous previous three days on icing thickness was obvious, while that in hilly and plain region was closely related to meteorological conditions on the day and previous day or two days. (2) The regional meteorological estimation model had a good effect on simulating wire icing thickness in each region of Shanxi Province, and the deviation was about 2 mm at Wutai Mountain station before the relocating, while that was less than 1.2 mm in other areas. (3) The results after the terrain correction could perform more reasonably the spatial distribution characteristics of wire icing thickness under different return periods in Shanxi Province. The wire icing thickness decreased with the decrease of latitude, the medium and heavy icing thickness mainly distributed in high elevation areas of Hengshan, Wutai, Guancen, Lvliang, Taiyue and Taihang Mountains, while the icing thickness was thin relatively along the Yellow River and in basin, and that in basin was the thinnest. (4) After the modification of operating experience in easily icing areas of power grid, the wire icing thickness could show more accurately the real situation of icing in local micro-terrain areas, which had practical reference value to electricity department.

Based on dynamic downscaling simulation data of temperature and precipitation by the regional climate model version 4 (RegCM4) from National Climate Center under the representative concentration pathways 4.5 (RCP4.5) and RCP8.5 scenarios, the simulation ability of RegCM4 was tested in baseline period (1986-2005). And on this basis, the climate change was analyzed in North China in future of the 21st century. The results show that RegCM4 had a better performance in simulating air temperature and precipitation in North China in baseline period. The change of surface air temperature, precipitation, consecutive dry days (CDD) and strong precipitation (R95p) under RCP4.5 and RCP8.5 scenarios will increase gradually in North China in future of the 21st century, but their changes under RCP4.5 scenario will be obviously less than those under RCP8.5 scenario. Under the higher emission scenario of RCP8.5, the annual mean air temperature will rise 1.77, 3.44 and 5.82 ℃ in near term (2021-2035), medium term (2046-2065) and long term (2080-2098) of the 21st century, the annual mean precipitation will increase 8.1%, 14% and 19.3%, CDD will reduce 3, 3 and 12 d, and R95p will increase 30.8%, 41.9% and 69.8%, respectively. In space, the mean air temperature in the whole year, winter and summer in North China will rise consistently in future of the 21st century, and the warming in summer will be the most, while the mean precipitation in the whole year, winter and summer will increase in most regions, and the increase of precipitation in winter will be the most. Meanwhile, CDD will decrease except in Shanxi and Beijing-Tianjin-Hebei areas in near term and medium term, while R95p will increase, which indicated that the drought events will reduce and the extreme precipitation will increase in the 21st century.

Based on the ozone mass concentration monitoring data near surface of Yinchuan and ground and upper meteorological observation data over Eurasian area from 2014 to 2016, the influence of meteorological conditions on ozone mass concentration was probed systematically from two aspects of meteorological factors and atmospheric circulation pattern. The results show that the ozone mass concentration near surface of Yinchuan was positively correlated with air temperature and negatively correlated with relative humidity, respectively. The vertical mixing played a dominant role when the wind speed was low, the ozone mass concentration was positively related with wind speed, while the horizontal diffusion played an important role when the wind speed was high, the ozone mass concentration was negatively related with wind speed. The southerly wind and wind direction towards Helan Mountain were conducive to the increase of ozone mass concentration. There were five circulation patterns on ozone polluting days in Yinchuan: trough and ridge pattern (44%), wide trough pattern (21%), subtropical high pattern (16%), northeast ridge pattern (8%) and others pattern (11%). The inversion layer near surface and sea-level low pressure system (or inverted trough) were important synoptic systems which caused ozone pollution in Yinchuan.

Based on the potato yield data in Hebei Province from 1983 to 2019, the average temperature, precipitation and sunshine hours every ten days from 21 meteorological stations during the same period, the meteorological key factors influencing potato yield were determined by means of factor puffing and correlation analysis. The forecast model of potato yield was established and this model was tested during 1983-2015 and was applied during 2016-2019. The results show that potato yield in Hebei Province was sensitive to temperature and sunshine from July to September, and the effect of temperature on potato yield was greater than sunshine hours. The average trend backtesting accuracy ranged from 75.7% to 91.7% for different initial forecast time, the average backtesting accuracy of forecast potato yield ranged from 83.6% to 91.4%, and the forecast accuracy of potato yield during 2016-2019 ranged from 83.5% to 95.3%, and with the backward of initial forecast time, the forecast accuracy improved gradually.

Based on daily meteorological observation data in main apple producing areas of China from 1971 to 2017, the crop coefficients at different growth stages of apple were corrected, firstly. And on this basis the precipitation suitability model at each growth stage of apple was constructed. Then, combined with the geographical distribution of apple in advantageous areas, the threshold of precipitation suitability of apple, and the spatial and temporal distribution characteristics of precipitation suitability at each growth stage of apple were analyzed. Furthermore, the temporal and spatial anomalies were discussed by using empirical orthogonal function (EOF) decomposition method. The results are as follows: (1) The thresholds of precipitation suitability at initial growth stage, vigorous growth stage and later growth stage of apple were 0.30-1.29, 0.63-1.78 and 0.62-2.84, respectively. The areas within the threshold range at each growth stage of apple accounted for 94.8%, 94.7% and 95.9% of main producing areas, respectively. The change trend of precipitation suitability in most regions at three growth stages of apple wasn’t significant from 1971 to 2017. (2) The variance contribution rates of the first eigenvector field of precipitation suitability at initial growth stage and vigorous growth stage of apple were 50.53% and 32.26%, respectively. The eigenvalues were almost positive in the whole region, which indicated that the spatial change of precipitation suitability had good consistency, and the oscillation intensity of precipitation suitability strengthened from northeast and southwest to the middle. The variance contribution rate of the first eigenvector field of precipitation suitability reached 49.51% at later growth period, and the distribution pattern in Liaoning Province and the local part of eastern Hebei Province was opposite to other areas. (3) The second eigenvector field of precipitation suitability appeared an opposite phase distribution pattern in the east and the west at initial growth period of apple, while that were anti-phase distribution pattern in northern and southern parts at vigorous growth period and later growth period of apple. 

The difference of land-atmosphere energy flux caused by the heterogeneity of underlying surface properties plays an important role in affecting the occurrence of local heavy precipitation. The transition of vegetation is fast in western part of the transition zone of China’s summer monsoon, the nature of vegetation is obviously different, and the surface heterogeneity is strong, so the extreme precipitation is prone to occurrence. In order to explore the influence of underlying surface heterogeneity on strong precipitation in this area, the characteristics of underlying surface were analyzed statistically. And on this basis the sensitivity tests with three or six kinds of landuse type and control test for a typical heavy rainfall process under the influence of the western Pacific subtropical high and cold air from 28 to 29 August 2017 were carried out by using the mesoscale model of WRF3.8 and NCAR-LSM land surface model. The influences of underlying surface change on rainstorm intensity, falling area and flux parameters were studied. The results show that the underlying surface with three to six kinds distributed in transition region of summer monsoon of China. The types of underlying surface were relatively few in eastern part of Qinghai to central Gansu, the heterogeneity was weak, while there were more than six kinds in southeastern part of Northwest China and northern Sichuan, the heterogeneity was strong. The proportion of representative vegetation in a single grid in the model was not high, and the contribution rate to land-atmosphere flux was less than 50%, which indicated that it was not suitable to consider the single underlying surface in calculating land-to-air flux during the heavy rain process. The area of precipitation with different magnitudes was closer to the actual situation with the increase of underlying surface types in the model, and the heterogeneity of land feature physical quantity strengthened in main rain zones. Compared with the control test, the simulated shallow surface temperature, surface heat flux, sensible heat flux and latent heat flux by two sensitivity tests reduced during the daytime, which shrank the bias to some extent, thus decreased convective available potential energy and restrained the occurrence of convective rainfall, further reduced the positive bias of precipitation.

Based on the data of wind and hail damage, drought, flood and chilling disasters in Northeast China from 1971 to 2016, disaster rate, hazard rate, no harvest rate, disaster intensity index and grain yield loss amount caused by agrometeorological disaster were calculated to analyze characteristics of agrometeorological disaster loss by using the methods of Mann-Kendall test and Morlet wavelet analysis. The results show that disaster rate and hazard rate of crop in Northeast China presented an apparent decline trend, and no harvest rate dominated by a significant upward trend. The disaster rate and hazard rate of drought were largest during 2001-2010, no harvest rate of drought was largest during 1991-2000, and disaster rate, hazard rate and no harvest rate of flood were larger during 1981-1990. Wind and hail damage, chilling had little influence on crop. The main period of wind and hail damage and chilling disasters were about 3 a, and those of drought and flood disasters were 3.5 a. The intensity index of drought disaster in Liaoning was largest, the wind and hail damage disaster in Jilin and Heilongjiang was largest, and the chilling disaster was smallest in three provinces. The yield loss amount of  grain caused by main agrometeorological disasters was mainly an upward trend, and yield loss rate of grain caused by disaster was mainly a decline trend. The largest yield loss caused by four types of disaster was found in Heilongjiang, followed by Jilin and Liaoning, and the largest grain yield loss rate caused by drought disaster was found in Liaoning, followed by Jilin and Heilongjiang. The grain yield loss amount and yield loss rate caused by drought were largest, followed by flood, and that caused by chilling was smallest. The disaster yield loss amount and disaster yield loss rate of drought and flood were significantly greater than that of wind and hail damage and chilling. Drought and flood were the most serious agrometeorological disasters in Northeast China.

Based on maximum wind speed data from 1971 to 2018 and extreme wind speed data from 2005 to 2018 in Jilin Province, extreme wind speed data from 1971 to 2004 were estimated by using the gusty coefficient method, and then the sequences of extreme wind speed from 1971 to 2018 was formed. On this basis, the spatio-temporal variation characteristic of extreme wind speed and its relationship with climate warming were analyzed by using methods such as accumulated departure, extreme value distribution Ⅰ type, and Mann-Kendall test. The results are as follows: (1) With the increase of wind level, the occurrence frequency of gale above level 8 decreased rapidly. (2) The annual extreme wind speed had double peaks in spring and autumn and double valleys in winter and summer. (3) Since the 1970s, the annual mean extreme wind speed in Jilin Province decreased 0.9 m·s-1 per decade, and the frequency of gale over level 8 showed a decreasing trend year by year. (4) The average extreme wind speed and the extreme wind speed under 10-year to 50-year return periods both showed the distribution with high values in the northwest and low values in the southeast, and the largest value of extreme wind speed under 10-year to 50-year return periods in Changchun ranged from 33.9 to 40.7 m·s-1. (5) The annual mean extreme wind speed and annual mean temperature presented obvious inverse correlation and inverse phase relationship. The abrupt change of annual mean extreme wind speed occurred around 1988, which coincided with the sudden change of temperature in the northeast of China. (6) Although extreme wind speed in Jilin Province decreased obviously due to climate warming, there were still extreme gales. From 2011 to 2018, there were 95 gales above grade 10 and some gales were even above grade 13. Therefore, it is still necessary to strengthen gale prevention.

In order to prevent and control drought and waterlogging disasters scientifically in Songliao Basin, the pentad precipitation concentration index (PCI) was calculated based on daily precipitation data at 196 weather stations of Songliao Basin from 1961 to 2017. And on this basis the temporal and spatial variation characteristics of PCI in Songliao Basin and its sub-basins were analyzed by using trend analysis, composite analysis and Mann-Kendall test, etc. The results show that the precipitation concentration degree in Songliao Basin was higher, and the average value of PCI during 1961-2017 was 7.1. The PCI and its standard deviation increased gradually from east to west in Songliao Basin, and the precipitation generally concentrated in less rain years, while that was relatively uniform in more rain years, which indicated that the probability of drought in PCI higher value area of northwestern Songliao Basin was larger, especially in less rain years. The decadal change characteristic of PCI in Songliao Basin was obvious from 1961 to 2017, and the PCI had significant downward trend in the north and east of Songliao Basin as a whole. The mutation of PCI in Songliao Basin and Erguna river sub-basin was significant from 1961 to 2017, it happened in 2003 and 1991, respectively, and their variation coefficients of PCI increased after the mutation. Although PCI in Songliao Basin was in a lower stage in recent years, the variation coefficients of PCI after the mutation increased and the instability of precipitation strengthened, which indicated that the probability of drought and waterlogging tended to increase, and the precipitation was easily to concentrate extremely.

The characteristics of the extreme drought event occurred from 1941 to 1943 in North China and its influence were analyzed in this paper． Results show that this drought event was the second extremely arid events during the Republic of China period，and He’ nan Province was the center of this event． It occurred on interdecadal relatively warm period and persisted long time． This drought event influenced so many provinces，and disaster was so serious with locust occurrence． It made population suffer severe losses and food prices soaring as well as ecological environment deterioration．
 

The characteristics and influence of the serious drought event lasting eleven years ( 1922 － 1932) in the Yellow River valley
was analyzed in this paper． The result shows that this serious drought event occurred at least once in two hundred years． It happened in
the relatively warmer period under the background of a century － scale drought，which was characterized by long time，wide area，and
heavy damage． During the period of 1922 － 1932，the natural disasters such as drought，locusts，earthquakes，pestilence intertwined
with the man － made disasters ( banditry and war) ，which led to a terrible calamity in the Yellow River valley，the entironment and agricultural
productivity suffered great devastation，and the people underwent all kinds of hardships．

Soil heat flux plays an important role in energy flux exchange between land and atmosphere, especially in arid and semi-arid region. Based on soil heat flux at Zhangye National Climate Observatory, the diurnal variation of soil heat flux and the relationship between that and radiation flux are analyzed under different weather conditions for clear, cloudy and rainy day.The results show that the soil accepted heat from the air on clear day, on the contrary, the output heat of soil exceeded the input on cloudy and rainy day. In addition, most values of soil heat flux are negative in autumn and winter season, and positive in spring and summer .

Based on five - layer wind speed, air temperature, humidity and vapor p ressure of the gradient tower of Zhangye National Climate Observatory built in 2007 from Sep tember 2007 to August 2008, the percentage of missing value was calculated, and the climate characteristics of Zhangye in different seasons were also analyzed. The reliability of data from the gradient towerwas checked by comparing with some other observational stations.

The extreme drought eventoccurred in Sichuan and Chongqing region during the period of1935-1937 was analyzed. Itwas an extreme drought event thatmeet in one hundred years in warmer climate period, itpersisted long time and disserved severely, and people’s life and wealth suffered bigness harm. The low ability ofdefence droughtdisaster resulted in seriouse calamity. People in Sichuan and Chongqing regionmust strengthen defence drought and reduction disasterwork under the back ground ofglobal climatewarming.

In the late spring and early summer of 2005，Yunnan encountered drought event，which was the severest in the recent 50 years．By comparative analysis．it was found that the main influence factors for this abnormal weather event weIe tlle delay of seasonal evolution of South Asia hish。and relatively weak cold air in polar region，as well as relatively strong of the subtropical hish over the western Pacific lying southwestwards resulted from meridional circulation over Asia，and lagging of the seasonal shift of circulation in middle—hish levels．

In the late spring and early summer of 2005，Yunnan encountered drought event，which was the severest in the recent 50 years．By comparative analysis．it was found that the main influence factors for this abnormal weather event weIe tlle delay of seasonal evolution of South Asia hish。and relatively weak cold air in polar region，as well as relatively strong of the subtropical hish over the western Pacific lying southwestwards resulted from meridional circulation over Asia，and lagging of the seasonal shift of circulation in middle—hish levels．