To identify the weather patterns and threshold values of meteorological factors associated with ozone (O₃) pollution in the central and western Inner Mongolia, the obliquely rotated Principal Components in T-mode (PCT), was used to analyze the surface and upper air circulation O₃ pollution process in six cities in the region from 2015 to 2021, the relationship between the weather situation, meteorological elements and O₃ pollution is discussed. The results show that the O₃ pollution process in central and western Inner Mongolia can be divided into three types in the 500 hPa circulation: the high pressure ridge, the westerly flow pattern in flat direction, and the northeast flow pattern in the bottom of high pressure. There are four types of sea level pressure field: pressure equalization,low pressure control, high pressure south, low pressure front. The circulation configuration can be divided into five types: high pressure ridge-pressure equalization field type, the northwest flow at the front of the ridge-low pressure control field,,the westerly flow pattern in flat direction- high pressure south field, the northwest flow at the front of the ridge-low pressure south field, and the northwest flow at the front of the ridge-pressure equalization field. In Alxa and Wuhai, the O₃ overrun is mainly found in the flat westerly-southern type of high pressure, while in other cities it is mostly found in the NW flow-high pressure-controlled type in front of the ridge. These two general circulation configurations are the main meteorological conditions for the occurrence of O₃ pollution. The typical regional O₃ pollution usually occurs in a specific atmospheric general circulation situation. When there is an inversion layer in the boundary layer, the stronger the inversion intensity is, the worse the vertical diffusion condition is, which is unfavorable to the near-surface pollutant diffusion. Meteorological factors such as surface maximum temperature, sunshine duration and average relative humidity have influence on O₃ pollution. In dry areas such as Alxa, Wuhai and Bayannur, O₃ mass concentrations are higher than normal, with maximum temperatures of at least 30℃ and hours of sunshine of at least 10 hours, while in relatively wet areas such as Ordos, Baotou and Hohhot, the maximum temperature is usually not less than 27 ℃ and the sunshine duration is not less than 8 hours when O₃ exceeds the standard. In addition, when the wind direction is southwest, south and southeast, and the wind speed is 2.0-5.0 m·s ^-1, O₃ pollution is easy to occur.

Improving the Temperature Vegetation Dryness Index (TVDI) and clarifying the agricultural drought grade threshold of TVDI is of great significance for improving the ability of TVDI to monitor agricultural drought. Based on MODIS (Moderate Resolution Imaging Spectroradiometer) remote sensing data in the past 19 years, several feature spaces are constructed by using the single-time and multi-time methods, including NDVI (Normalized Difference Vegetation Index) -LST (Land Surface Temperature), EVI (Enhanced Vegetation Index) -LST, RVI (Ratio Vegetation Index) - LST, and SAVI (Soil Adjusted Vegetation Index) -LST. The calculation methods of TVDI are discussed, the applicability of TVDI for agricultural drought monitoring in Gansu Province is analyzed, and classification standards for summer TVDI agricultural drought in Gansu Province are clarified. The research results are as follows: 1) The TVDI calculated from the SAVI-LST feature space is more suitable for agricultural drought monitoring in Gansu Province. The root mean squared error (RMSE) and mean absolute error (MAE) of its fitting relative soil moisture (RSM) decreased by 1%-5% compared with the RMSE and MAE of RSM fitted by NDVI-LST feature space TVDI for RSM, which is used more commonly. 2) TVDI is suitable for agricultural drought monitoring at shallow depths of 10 and 20 cm in non-arid areas such as semi-arid, semi-humid and humid areas in Gansu Province in summer. The RMSE and MAE are approximately 15.6% and 12.6%, and the fitting errors in humid areas are the least, and they are less in semi-humid areas than in semi-arid areas they are the largest. 3) Compared to TVDI drought grades divided by 0.2 intervals and TVDI with uncertain classification criteria, the TVDI agricultural drought grade determined by the linear relationship between TVDI and RSM is more conducive to improving the accuracy of TVDI monitoring agricultural drought.

The warming trend of the global climate system continues, and the impact on natural ecosystems and water resources continues to rise, aggravating the already fragile global water resources. At this background, as a potential water resource, non-precipitation water (NPW) in arid area plays an important role in the maintenance of ecosystem and land surface water balance in arid area. Therefore, based on the present results of international research on NPW, the development process of NPW is summarized. The observation methods, variation characteristics, formation mechanism and the contribution of NPW to land surface water balance and its effects on crops in arid areas of Northwest China were reviewed. Finally, on the basis of combining the international frontiers, hot issues and development trends of NPW research, the shortcomings and problems of current NPW research are analyzed scientifically. It is pointed out that the study of NPW should focus on further revealing the complex formation mechanism of NPW on land surface, and strengthen the cognition of NPW in different climatic regions and different underlying surfaces. Breakthroughs have been made in key scientific issues such as the establishment of a specially targeted land surface NPW observation system, the development of the parameterization of land surface NPW in the numerical model, and the research and development of technical standards for the development and utilization of land surface NPW.

The summer monsoon transition zone in China is one of the regions with strong land-atmosphere interaction in the world, and it is also an area where extreme weather disasters are frequent and easy to cause serious economic losses. Further understanding of land-atmosphere interaction in the transition area will help to improve the disaster prevention and mitigation ability of this region. Based on the research results of the summer monsoon transition area related projects carried out by the Key Laboratory of Drought Climate Change and Disaster Reduction of China Meteorological Administration in recent years, this paper systematically summarizes the new progresses of land-atmosphere interaction in the summer monsoon transition zone, including the spatio-temporal distribution law of land-atmosphere interaction in the transition region, the new characteristics of the response of land surface water budget to summer monsoon, the spatio-temporal variation characteristics and development mechanism of the boundary layer, the influence of monsoon and land-atmosphere interaction on regional climate in the transition zone, the new progress of land-atmosphere interaction on crop yield in the transition zone and new schemes for parameterization of multi-factor and multi-scale kinetic roughness. According to the development trend of land-atmosphere interaction research in the summer monsoon transition zone, it is proposed that the multi-scale dynamic response of land-atmosphere interaction to summer monsoon should be explored in the future, and the climatic dynamic relationship between surface processes and key physical quantities in the atmospheric boundary layer should be established on the basis of the research on the response rule of land-atmosphere exchange multi-cycle process to the annual cycle of summer monsoon in order to improve and enhance the simulation of regional climate models in the future. This work is of great significance to promote the research of land-atmosphere coupling process in China, which can provide scientific and technological support for disaster prevention and mitigation in the summer monsoon transition zone in China.

Based on thunderstorm gales data in recent 40 years and the conventional and new monitoring data in recent 18 years in Shanxi Province, the spatial and temporal distribution of thunderstorm gales in Shanxi Province are analyzed firstly, and then the weather types, characteristic physical quantity thresholds and conceptual models of thunderstorm gales are studied by using the methods of cluster analysis and mesoscale weather analysis. The results show that the average number of thunderstorm gale days in Shanxi had the regional distribution characteristics with more in the north and less in the south, more in mountainous areas and less in plain, and more in western mountainous areas and less in eastern mountainous areas. The extreme thunderstorm gales mainly occurred in the north of Shanxi and Lüliang mountainous regions. The annual thunderstorm gales days in the western mountainous area showed an increasing trend, while there were no changes or decreasing trends in other areas. The thunderstorm gales mainly occurred from May to August, accounting for 75% of the total days of thunderstorm gales in the whole year, and thunderstorm gales occurred most frequently at 16:00 and 21:00 (Beijing Time) in a day. The flow patterns of thunderstorm gales in Shanxi are mainly divided into six types, which are forward-tilting trough, backward-tilting trough, transverse trough, subtropical high and low-level warm shear line, subtropical high and low-level cold shear line, and northwest air flow. The K index threshold of all patterns from April to May was significantly lower than that from June to September, while the temperature difference between 850 hPa and 500 hPa was obviously higher than that from June to September. When each pattern meets the characteristic physical quantity thresholds of each month, it can trigger the strong thunderstorm gale weather in Shanxi, while the flow pattern configuration of forward-tilting trough has the highest percentage of triggering extreme thunderstorm gales. Over the same period, the K indices of the patterns of backward-tilting trough, subtropical high and low-level warm shear line, subtropical high and low-level cold shear line are significantly higher than those of the patterns of forward-tilting trough and northwest air flow, while the Si index of the forward-tilting trough is obviously higher than that of other patterns, which indicated that the dynamic instability condition of the forward-tilting trough triggering thunderstorm gale is better than the thermal instability condition. The CAPE and 0 ℃ layer height thresholds of the patterns of subtropical high and low-level warm and cold shear lines are significantly higher and the thresholds of T-T_d and cloud top black body temperature in the lower layer are significantly lower than those of the other four patterns. Whether hail is accompanied by thunderstorm gale process can be accurately judged by 0 ℃ layer height threshold of each month.

A complete century series of temperature is the basis of climate change analysis. The local century temperature changes have general characteristics, also retain some differences. Based on temperature observation data at Wuhu station of Anhui Province during 1880-1937 and 1952-2020 and CRU (Climatic Research Unit) grid data of University of East Anglia during 1901-2020, the test and correction to observation data of temperature were conducted to obtain high quality data. And on this basis that the time series of temperature from 1880 to 2020 at Wuhu station was constructed by using the multiple stepwise regression method, its decadal characteristics were analyzed. The results show that the quality of monthly mean temperature at Wuhu station from 1880 to 1937 was improved after the difference and homogeneity corrections. Two temperature series were constructed by using the stepwise regression analysis based on CRU grid data during 1901-2020 and station observation data during 1901-1937 and 1953-2020, and the interpolated temperature by their average value could display perfectly the variation characteristic of monthly mean temperature at Wuhu station during 1938-1951. The spring, summer and winter temperature increased significantly at Wuhu station in past 140 years, and the increasing rate of spring temperature was the maximum, followed by summer and winter, while the warming in autumn wasn’t significant. The decadal characteristic of coldness and warmness alternation was obvious in each season from 1880 to 2020, but the warming stalled in recent 20 years. In addition, there were 40-50 a and 20-30 a periodic oscillations of mean temperature.

In order to overcome the shortage of disaster condition records and the difficulty of identification to drought effect at each growth stage, based on daily meteorological data at weather stations, growth period data at agro-meteorological stations and rice yield data in counties of Sichuan Province from 1981 to 2015, with improved water budget index as drought indicator, the relationship between drought and yield at each growth stage of rice was analyzed by using grey correlation analysis method. The results show that the drought frequency at growth stages of rice in Sichuan from high to low was transplanting-tillering stage, tillering-jointing stage, booting-heading stage, heading-maturity stage and jointing-booting stage in turn. The spatial characteristic of rice drought frequency at each growth stage was low consistent with the spatial distribution of grey correlation degree between water budget index and rice yield. The high frequency of drought occurred in the middle or northeast of Sichuan Basin, while the high grey correlation degree located in the mountainous areas around the basin edge and Panxi area. With the process of rice growth, the effect of drought on rice yield weakened, and at transplanting-tillering and tillering-jointing stage it was the most obvious. The growth period with the greatest influence of drought on rice yield was different in each county of different planting regions, so the policies of drought alleviation should be strengthened according to the spatial characteristics of drought influence at each growth stage of rice. We should focus on the drought at tillering-jointing stage of rice in planting regions of the Chengdu Plain and the central hill of Sichuan Basin and transplanting-tillering stage in other five rice planting regions.

Drought is one of the natural disasters with the widest global impact. The anomalous drought and heatwave event that occurred in the Yangtze River Basin in summer of 2022 is not only of high intensity but also of long duration, it is a rare and significant drought event leading to very serious socioeconomic impacts in China. In view of the extreme nature of this event, this paper reveals the possible influence of atmospheric circulation and external forcing anomalies on this drought event based on an objective analysis of the evolutionary characteristics of this event. It is found that the meteorological drought index and soil moisture monitoring results consistently indicate that this drought event started to appear in June, developed rapidly in July, and further expanded and intensified in both extent and intensity in August. At the same time, the overall temperature in the basin was high, with the number of high temperature days exceeding 40 days in some areas. In addition, anomaly of evapotranspiration over the basin in summer was the second highest on record since 1960, second only to the high temperature drought event in 2013, which further exacerbated the degree of water deficit in the Yangtze River Basin. From the perspective of circulation characteristics, the abnormal intensifying and westward extension of the western Pacific subtropical high pressure, the small area and weak strength of the polar vortex and the intensifying and eastward shift of the South Asian high pressure in summer jointly led to weak water vapor transport conditions and prevailing sinking air currents in the Yangtze River Basin, making the overall conditions unfavorable for the occurrence of precipitation. The persistence of the La Niña event, the appearance of negative Indian Ocean Dipole (IOD) and the persistence of the negative snow cover anomaly in the northwestern Tibet Plateau in spring may be the main external forcing factors leading to the circulation anomaly in this summer.

Cloud is a key modulator of the energy budget in earth-atmosphere system. The macro- and micro-physical parameters of cloud have an important influence on precipitation intensity and distributions in arid region. In order to clarify the macroscopic characteristics of cloud in the hinterland of Taklimakan Desert (TD), the structures of cloud layers were continuously detected at Tazhong station from July 23 to September 30 in 2019 by using the CHM15K ceilometer. The variation characteristics of cloud base height, cloud layer thickness, and total cloud coverage were analyzed over Tazhong station in August and September 2019. The results show that the ceilometer could clearly observe the distributions of cloud layer and rainfall processes over TD. The average cloud base height at Tazhong station was about 4.6 km in August and September 2019.The high and middle level clouds predominated at Tazhong station. And the sum of proportions of high and middle level clouds exceeded 90% in August and September, and the proportion of single-layer cloud was significantly higher than that of multi-layer cloud. The cloud layer thickness at Tazhong station was relatively small, the average thicknesses of the first cloud layer were 402 m and 532 m in August and September, respectively, corresponding cloud layer thickness less than 500 m accounted for 64.2% and 58.8%. This implied that the cloud layers were geometrically thin at Tazhong station in August and September 2019. The results of total cloud coverage indicated that the proportion of all-sky cloud day in August was highest (32.6%), whereas the proportion of cloudless sky in September was highest (40.8%), which suggested that clear-sky days were dominant in September. The results of this study will help to understand the spatial and temporal distributions and evolution features of cloud macroscopic characteristics over the hinterland of TD, which provide invaluable datasets for validation of numerical model simulations and satellite remote sensing products.

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.

Based on the hail data from eleven ground meteorological observation stations in the eastern agricultural region of Qinghai Province from 1961 to 2020, the temporal and spatial distribution of hail days, hail diameter, duration and disaster risk characteristics were analyzed by using statistical methods. The main conclusions are as follows: (1) The hail days in the agricultural area of eastern Qinghai Province decreased with climate tendency rate of 11.6 d·(10 a)^-1 in the past 60 years, which passed the significance test of \alpha=0.05, and after 1995, the anomaly of the total number of hail days changed from the positive to the negative. Hualong was the area with the largest number of hail days, and the number of hail days in Jianzha was the least. (2) Hail occurred mainly from May to September each year with seasonal differences. The diurnal variation of hail was obvious, and the peak occurred at 16:00 BST in the afternoon. (3) The number of hail days was positively correlated with altitude of stations and the correlation coefficient between them was as high as 0.97.(4) In the past 60 years, the hail processes with hail diameter less than 6 mm and the duration less than 9 min accounted for 58.33% and 73.55% of the total number of hail processes, respectively. (5) Xunhua was a low-risk area for hail, Hualong, Huangzhong and Huangyuan were medium-risk areas for hail, and Ledu was a high-risk or extremely high-risk area for hail, which was basically consistent with historical hail disasters.

The automated soil CO₂/gas flux system (model LI-8100A) was used to continuously observe the soil respiration rate, soil temperature and water content in a semi-arid grassland of Loess Plateau during the growing season (from May to October). The temporal variations of soil respiration were comprehensively analyzed, and the influences of environmental hydrothermal factors on soil respiration were studied. The results are as follows: (1) The diurnal dynamic variations of soil respiration rate were significantly different under diverse weather conditions, and the daily mean value (2.90 µmol·m^-2·s^-1) and variation range (1.73-4.92 µmol·m^-2·s^-1) on sunny days were obviously greater than those on cloudy and overcast days. The average diurnal variations of soil respiration rate in different months all showed a significant unimodal pattern, with the maximum (2.20-4.40 µmol·m^-2·s^-1) appearing at 12:00 BST or 13:00 BST and the minimum (0.71-1.70 µmol·m^-2·s^-1) appearing at 05:00 BST or 06:00 BST. The daily mean values were close to the observed values at 10:00 BST or 19:00 BST. (2) The soil respiration rate in both daytime and nighttime were low in May and June, and increased gradually from June, then reached the peak value (in daytime 3.31±0.98 µmol·m^-2·s^-1, in nighttime 1.80±0.39 µmol·m^-2·s^-1) in August, afterwards gradually decreased. Furthermore, the lowest value occurred in October (in daytime 1.55±0.55 µmol·m^-2·s^-1, in nighttime 0.81±0.12 µmol·m^-2·s^-1), and soil respiration rates in daytime were always higher than those in nighttime. The nocturnal soil respiration contributed 27.2%-32.4% to the total respiration during the whole growing season. Therefore, the effects of nocturnal soil respiration should be considered in the current carbon cycle models of grassland ecosystem. (3) Soil temperature was the main environmental factor affecting soil respiration rate, but the univariate model of soil temperature was not enough to fully explain the diurnal dynamic changes of soil respiration. The bivariate nonlinear model combined with soil temperature and water content could be better fitted the soil respiration rate and accounted for 74.0% of the variation. (4) The temperature sensitivity indices (Q₁₀) of the entire day, daytime, and nighttime throughout the growing season in 2020 varied from 1.38 to 2.14, from 1.22 to 1.96, and from 0.85 to 1.64, respectively, with the corresponding mean values of 1.58±0.23, 1.41±0.19 and 1.20±0.16. This suggested that replacing the daily mean values of Q₁₀ with daytime averages would result in an underestimation of about 10.8%.

Based on conventional meteorological observation data of Zhejiang Province, ERA5 hourly reanalysis data (0.25°×0.25°) and blackbody brightness temperature (TBB) of FY-4A satellite, the two rainstorm processes occurring on June 3 and June 30 in 2020 were compared and analyzed. The results are as follows: (1) The rainstorm on June 3 (short for “6·03”) occurred in the background of monsoon trough, and there were southwest flow in front of the trough at 500 hPa and warm shear at 850 hPa over Zhejiang Province,while the rain storm on June 30 (short for “6·30”) occurred in the background of northeast cold vortex, there were confluence of cold and warm air at 500 hPa and cold shear at 850 hPa. For two rainstorm processes, their rainfall areas were similar, all concentrating in west Zhejiang and presenting east-west belt distribution. But for the “6·30” process, the rainfall area was wider, both the center rainfall and process rainfall were larger, the hourly rainfall intensity was stronger, and the duration of heavy rainfall was longer. (2) Both two rainstorm processes were convective unstable precipitation, but the heavy rainfall areas were in different positions of the jet stream. The “6·03” process was a warm shear type rainstorm in the warm region, the “train effect” of convective cloud clusters was significant and precipitation was located in the strong convergence area of water vapor flux in front of the jet. During the “6·30”, the Meiyu front was a westerly convergence frontogenesis, and the convective cloud clusters presented a backward propagation path, the precipitation was located in the strong convergence area of water vapor flux near the jet axis. The maximum convergence area of water vapor flux and intensity at 700 hPa corresponded to the falling area and intensity of heavy precipitation in the next six hours, which had a certain reference in rainstorm forecast in the Meiyu season. (3) Due to different precipitation types, the corresponding frontogenesis was different, and the height of the frontal zone indicating one hour heavy rainfall was also different. So in the forecast of rainstorm in the Meiyu season, the correspondence of different precipitation types and frontogenesis at different heights should be fully considered.

Based on daily precipitation data from 44 national meteorological stations in the southern Xinjiang and the NCEP/NCAR reanalysis data from May to September (warm season) during 1961-2020, the spatial and temporal variation characteristics of rainstorm and large-scale circulation anomalies under different decades and climatic background (warm-dry period and warm-wet period) in the southern Xinjiang were analyzed. The results show that the cumulative rainstorm days, rainstorm stations and rainstorm rainfall in the warm season of the southern Xinjiang has been increasing since 1961, but the variation trend of rainstorm intensity and the proportion of rainstorm rainfall in total precipitation was not obvious. The cumulative rainstorm days, rainstorm stations and rainstorm rainfall in the warm-wet period in the southern Xinjiang were significantly more than those in the warm-dry period, and the rainstorm intensity and the proportion of rainstorm rainfall in the total precipitation had little difference in the warm-wet period and the warm-dry period. After entering the warm-wet period, the rainstorm days and rainstorm rainfall amount increased in most stations in the southern Xinjiang (the most obvious increase was at southwest stations), but the increase extent in mountain area was smaller than that in plain. The central Asian trough, central Asian vortex and Tarim easterly low level jet were the main influencing systems for the heavy rain in the warm season in the southern Xinjiang. The heavy rain in the warm season in the southern Xinjiang was dominated by low vortex type in the warm-dry periods, and low trough type in the warm-wet periods. The easterly flow 850 hPa extended westward more obviously in the low vortex rainstorm than in the low trough rainstorm. In the circulation difference field between the warm-wet periods and the warm-dry period, the circulation anomaly in the high latitude area of the low trough rainstorm and the low vortex rainstorm showed reverse change characteristics.

There are some systematic biases in prediction of solar radiation based on numerical models, the AVT method has been verified to reduce the prediction bias effectively. The AVT correction method was used to modify the forecasted solar radiation in two photovoltaic power plants in Hexi area of Gansu Province. The results state: (1) Before correction the forecast bias presented obviously diurnal variation with increase first and then decrease, while it wasn’t obvious after correction. There was a strong linear relationship between forecast deviation of solar radiation and observed values before correction, while it got weak after correction (the correlation coefficient and good fitting degree decreased). (2) There was obviously annual change characteristic of solar radiation with the highest forecast bias in spring, followed by summer, autumn and winter. After correction, its forecast bias was reduced in four seasons, especially in spring and summer.

The abundant water vapor supply is a necessary condition for heavy rainfall, especially in arid area with complex terrain on southern slope of the Tianshan Mountains. Based on daily precipitation at sixteen weather stations of southern slope of the Tianshan Mountains and NCEP/NCAR GDAS reanalysis data from May to September during 1981-2020, the circulation situation of rainstorms in warm season on southern slope of the Tianshan Mountains was analyzed, and the water vapor source and transport trajectory was simulated and clustered by using HYSPLIT model and cluster analysis. The results show that the rainstorms in warm season on southern slope of the Tianshan Mountains mainly occurred over the overlap area of the South Asia high pressure with double pattern, southwesterly jet (airflow) above 500 hPa, 700 hPa shear convergence and topographic force lifting of the Tianshan Mountains. Water vapor mainly came from Central Asia, the Atlantic Ocean and its coasts, the Mediterranean Sea and the Black Sea and adjacent areas, through the key areas of TKAP (Tajikistan, Kyrgyzstan, northeastern Afghanistan, northern Pakistan and northwestern India), southern and northern Xinjiang, it mainly transported into rainstorm areas by the westerly, southerly, northerly channels, respectively. The water vapor above 700 hPa and below 700 hPa over rainstorm areas mainly came from the westerly and northerly channels, respectively, and the contribution of water vapor in the key area of southern Xinjiang to rainstorms was the maximum. The water vapor from central Asia mainly transported to 700 hPa and below, the contribution to rainstorms was greater, and the damage of water vapor was more along the transport way, while the water vapor from the Atlantic Ocean and its coastal areas, the Mediterranean Sea and the Black Sea mainly transported above 700 hPa, and the contribution to rainstorms was relatively smaller. In additional, the water vapor in middle and lower troposphere came from northern and southern Xinjiang, eastern North America and Mongolia. Based on the above characteristics, a three-dimensional fine structure model of water vapor for rainstorm processes in warm season on southern slope of the Tianshan Mountains was established.

Atmospheric precipitable water vapor (PWV) is an important factor affecting rainfall. Based on ground-based GPSretrieved PWV data, ground meteorological observations, sounding data and ERAInterim reanalysis data from 2010 to 2019, the seasonal, monthly and diurnal variation characteristics of water vapor resources over Fujian were analyzed. Moreover, the spatial and temporal characteristics of PWV were assessed by using the empirical orthogonal function (EOF), MannKendall test and the sliding t test. The results show that the accuracy of the groundbased PWV was higher compared with ERAInterim reanalysis data. The water vapor resource over Fujian was largest in summer, followed by spring, autumn and winter. The monthly distribution of PWV presented an inverted Ushaped, and the diurnal variation of PWV changed significantly on sunny day and rainy day. The PWV of the eastern coastal areas was generally higher than that of the western mountainous areas, but the precipitation conversion rate of PWVthere was lower than that of the inland mountainous areas. The first mode of EOF decomposition of PWV presented the main characteristics with a variance contribution rate of 80.06%. The eigenvalues were positive in the whole region, which indicated that the spatial change of PWV had good consistency. The oscillation intensity of PWVstrengthened from northwest and southwest to the east, and the corresponding time curve characterized the significant seasonal changes of PWV. The mutation test of MannKendall and the sliding t test showed that the water vapor resources over Fujian had not undergone abrupt change in the past 10 years.

 Based on the Lband sounding data, automatic weather station data, conventional observation data, NCEP global 1°×1° reanalysis data, the formation mechanism, characteristics of development processes and transmission mechanism of a persistent advection fog occurring over the north of the Yellow Sea during 23-24 April 2012 were analyzed. The results show that this fog belongs to an advection cooling fog. It was a result of interaction between cold sea surface and warmwet air flow. The sustained ridge over the Yellow Sea blocked and weakened the cold air, and it was favorable in establishment of a stable stratification in the lower layer of atmosphere. The sustained and strengthened transport of moisture by the southerly in the lower layer over the Yellow Sea not only provided abundant moisture for formation of the fog but also facilitated northward spreading of the fog areas. The “warm dry layer” above the fog layer and the underlying cold waters in the northern Yellow Sea were the primary factors for development and maintenance of this advection fog. The dense fog area corresponded to the cold advection area and the moisture convergence zone in the nearsurface layer. The area of merging of the cold and warm advections was prone to fog occurence. Under stable synoptic situation, the increase of southerly wind speed in the northern Yellow Sea did not affect maintaining of the advection fog. This unique character can be evidently distinguished from radiation fog.

 Based on the hourly precipitation data of 10 national meteorological stations from 2012 to 2019, the diurnal variation characteristics of precipitation in different seasons in the Yili River Valley of Xinjiang were analyzed. The results are as follows: (1) The diurnal variation characteristics of cumulative hourly precipitation in the Yili River Valley showed a single peak in spring, summer and winter, and a double peak in autumn. The low value period of diurnal accumulated hourly precipitation in four seasons appeared in the afternoon (15:00-19:00), the high value period appeared in the morning (10:00-12:00) in spring, autumn and winter, and in the first half of the night in summer (22:00). (2) The diurnal variation characteristics of cumulative precipitation frequency and cumulative precipitation in the same season were similar. There were significant regional differences in spatial distribution of hourly average precipitation and peak precipitation frequency. (3) Shortduration precipitation events were the main events in four seasons in the Yili River Valley, with the highest proportion (89%) in summer and the lowest proportion (70%) in winter. Short duration precipitation events were the main contributors to total precipitation in summer, while long duration precipitation events were the main contributors to total precipitation in winter. (4) There was a close relationship between the daily circulation of precipitation and the persistence of precipitation in four seasons in the Yili River Valley. The precipitation events lasting for 2-8 hours and 1-4 hours were the main contributors to the diurnal variation of precipitation in spring and summer. Three types of precipitation events with different durations had roughly equal contributions to the diurnal variation peaks of precipitation in autumn and winter in the Yili River Valley.

As an effective method to reduce the uncertainty of numerical models, the ensemble forecast has been widely applied to numerical weather prediction(NWP) of severe weather processes such as heavy rainfall and severe convective weather. Based on the research progress of WRF model ensemble forecast in China and abroad, this paper summarizes and reviews the improvement of initial field of WRF model, the construction of perturbation method of ensemble forecast and the development of convection-scale ensemble forecast. The results show that the data assimilation technology can provide micro-scale and meso-scale information for the initial field of large-scale model, which is beneficial to improve the forecasting ability about severe weather processes. The construction of reasonable multi-initial values, multi-boundary and multi-physical processes perturbation schemes in ensemble forecast can accurately characterize the uncertainty of atmospheric evolution, and thus improve the dispersion of ensemble forecast and obtain the more accurate result than deterministic forecast. Convection-scale ensemble forecast can simulate severe weather processes better, but how to develop the perturbation methods and evaluation methods to apply to convective-scale ensemble forecast is a difficult problem for the study of convective-scale ensemble forecast.

Based on CMA Tropical Cyclone Yearbook，FY-2G temperature of brightness blackbody (TBB) product (0.1°×0.1°), hourly rainfall observations from automatic weather stations, conventional observation and ERA-Interim reanalysis data（0.125°×0.125°）, the heavy precipitation process in the Liaodong Peninsula caused by typhoon Rumiba (1818) was analyzed preliminarily. The major conclusions are as follows: (1) The difficulty of “Rumiba” prediction was to predict the turning point and the track after landing. The eastward movement of westerly trough and continental high blocked the westward movement of “Rumiba”. The northward position of the subtropical high caused by northwesterly movement of typhoon “Soulik” and the continental high in northeast China were favorable for the northward movement of “Rumiba”. (2) The low-level southeast jet forming between typhoon “Rumiba”, “Soulik” and the subtropical high provided continuous water vapor and energy, which was conducive to maintaining the intensity of “Rumiba” and inducing continuous occurrence of the heavy precipitation in the Liaodong Peninsula. (3) The interaction of “Rumiba” in transformation process with westerly trough and low-level jet was beneficial to the development of spiraling cloud system on its north side. The heavy precipitation area was closely related to the cold and warm advection in the convergence zone of the north side of low-level typhoon circulation. And the energy front zone appearing at the intersection of cold and warm advection was a good indication for heavy rainfall. (4) There were great differences in the prediction of turning point and path after turning from numerical prediction models. In addition to referring to ensemble prediction products, the similarity prediction method can also be used to compare and analyze the large-scale environmental field of the similar individual cases, and the correction can be carried out with the help of the numerical prediction products and the similar individual cases.

Five winter wheat cultivars from the north and south wheat areas were selected as experimental materials. Through the different sowing date test, the amino acid quality of winter wheat grain was evaluated by variance analysis, principal component analysis and cluster analysis. Based on typical correlation and stepwise regression analysis, the correlation between winter wheat amino acid quality and climatic-biological factors was studied, and significant relevant climatic ecological factors were selected to construct winter wheat amino acid content prediction model. The results show that the average content of glutamate (non-essential amino) was the highest in amino acid contents of winter wheat, and the average content of methionine (essential amino acid) was the lowest. The environmental adaptability of essential amino acids and non-essential amino acids was relatively strong, while semi-essential amino acids had a greater potential for quality breeding. The content of amino acid in winter wheat showed the regional distribution characteristics that for northern varieties it was higher than that of southern varieties. The regional differences of threonine, phenylalanine, arginine, aspartic acid, glutamic acid and glycine were significant. The amino acid quality could be explained by three principal components with a cumulative contribution rate of 97.796%. In the comprehensive quality evaluation, the Gucheng Tanmai 98, and Taian Shannong 18 performed better, while the Jingzhou Zhengmai 9023, Suzhou Wanmai 52, Xuzhou Xumai 33 performed poorly. The cluster analysis showed that the cluster arrangement was closely related to the content of amino acid components and geographical distribution of winter wheat. The types I, II, III and IV were the Tanmai 98 in the north wheat area, the Shannong 18 in the northern part of Huanghuai wheat area, the Wanmai 52 in the southern part of Huanghuai, the Xumai 33 in the southern wheat area of Huanghuai and the Zhengmai 9023 in the Jianghuai wheat area, respectively which was consistent with the comprehensive evaluation ranking in the principal component analysis. The correlation between amino acid content of winter wheat and climatic-biological factors was obvious. The essential amino acid content was most correlated with temperature and humidity conditions. Most of the amino acid components could be improved in quality by adjusting the microclimate environment or soil moisture.

Based on the precipitation data of 6 automatic stations during 2013-2017 in the Yigeziya River Basin in Aktao county of Xinjiang and 7 national meteorological stations during 1961-2017 around the basin, the function relation between flood depth and rainfall was constructed by using FloodArea model in order to explore the threshold of disaster-causing critical rainfall under different recurrence periods of mountain flood. The hourly inundated area and inundated depth were simulated by hydrodynamic model. Combined with the disaster-affected factors (population distribution, GDP, land-use types) in the study area, the flood disaster risk zoning of the basin was completed. The results show that the middle and lower reaches of the basin was the high risk area of flood disaster risk, while the relatively high altitude area in the upper reaches of the basin was the low risk area of flood inundation.