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.
In order to improve the fine defense ability of late frost disaster in the vineyards in the eastern foothills region of the Helan Mountain, the minimum temperature observation data of the vineyards from April to May during 2020-2023 were used to analyze the variation characteristics of minimum temperature, the occurrence frequency and regional distribution characteristics of late frost in the vineyards. Based on the European Centre for Medium-Range Weather Forecasts (ECMWF) model forecast products and the actual temperature of grid points in Ningxia, the radial basis function (RBF) neural network algorithm was used to construct the minimum temperature and frost prediction model in the vineyards in the eastern foot of the Helan Mountain. The results show that the light frost was the most common in the vineyards in the eastern foothills region of the Helan Mountain, followed by the medium frost. April was the main month for frost occurrence. The frost in D.F. Yuxing winery appeared most frequently, and the frost in Guanlan winery was the least. The verification results of the minimum temperature and frost forecast show that compared with the ECMWF model, the RBF model has improved the accuracy of the minimum temperature forecast in the Helan, Yongning and Hongsipu production areas, with the highest increase of 33.8%, and the average absolute error reduced by 0.20-1.50 °C. For the single station frost forecast, the RBF model has obvious advantages, the accuracy rate generally increased by 1.0%-14.0%, and the average absolute error reduced by 0.04-0.37 °C. For the average of the production areas, the RBF model has the highest accuracy of frost prediction in the Hongsipu production area, up to 13.0%. In the case analysis of frost, the RBF model has better prediction effect, especially for moderate frost prediction. Compared with the ECMWF model, the accuracy rate increased by 25.0%-50.0%, and the average absolute error reduced by 1.80-2.10 °C.
As an ecologically fragile region, the mass concentration of atmospheric particulate is an important indicator of ecological security. It is of great significance to study its temporal variation and influencing factors for environmental and ecological protection in this region. Based on the surface meteorological data from Gonghe County Meteorological Bureau and PM10 mass concentration data at monitoring site of Hainan Prefecture Ecology and Environment Bureau in Qinghai Province from 2015 to 2020, the variation characteristics of PM10 mass concentration and its influencing factors in the Gonghe Basin are analyzed. The results show that downward trend of PM10 average mass concentration at annual time scale, in spring and winter is significant, while in autumn and summer it is insignificant. The average monthly distribution of PM10 mass concentration presents a bi-modal pattern. In spring, PM10 mass concentration remains high due to the combined influence of southeasterly and northwesterly wind-dominated, by which pollutants is transported horizontally to the Gonghe Basin. In winter when westerly wind prevail, PM10 mass concentration is second. With the arrival of the rainy season in summer and autumn, southeastly wind prevails in the Gonghe Basin, and pollutant horizontal transport weakens, and PM10 mass concentration is low. The monthly average PM10 mass concentration is positively correlated with monthly average wind speed, especially, the PM10 mass concentration reaches the highest in spring when wind speed becomes greater. The cold air activity is the main reason to cause PM10 heavy pollution in the Gonghe Basin, and there are two paths of air mass influencing heavy pollution in the Gonghe Basin, one is from southwest, and the other is from west.
Based on the hail weather observation data of 84 surface meteorological observation stations in Guizhou Province from 1961 to 2020, the temporal and spatial distribution characteristics of hail are analyzed, the features of hail weather such as regularity of the occurrence dates of the first and last hail, hail diameter and duration of a hail are explored further. Finally, suggestions for artificial hail prevention are proposed. The results show that the spatial distribution of annual average hail days in Guizhou was uneven, there was a regional difference which is the annual average hail days is more in west than in east and the annual average hail days is more in central than in north and south. Hail days decreased significantly （P<0.01） in the past 60 years. The frequent months of hail in Guizhou is from February to May, accounting for 85.0% of the annual hail days, the frequent period of hail is from 14:00 BST to 02:00 BST of the next day. In past 60 years, the average time of the first hail in Guizhou starts from east to west from late February to mid May, and the last hail ends from east to west from late March to late July. The occurrence frequency of middle-diameter hail accounts for 68.9%, and the duration of a hail is mainly concentrated within 10 minutes. Due to the obvious regional differences in seasonal and diurnal variation, and the occurrence dates of the first and last hail, local hail regularity should be fully mastered when carrying out hail prevention, and various artificial hail prevention work should be arranged reasonably.
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.
Based on the meteorological data of 8 sets of microclimate monitoring stations in the grape producing area in east foothills region of Helan Mountain and Yinchuan national reference station in 2019, the climate difference between Yinchuan station and the representative station was compared and analyzed, and the vertical changes of meteorological elements at Meiyu Winery were analyzed. The microclimate differences at four wineries in the same climate zone and five sub-regions in different climate zones were analyzed. The results are as follows: (1) Meteorological elements at Meiyu Winery and Yinchuan station in the same region were significantly different. (2) The 10 cm soil temperature fluctuated most and 40 cm soil temperature was most stable on a typical sunny day. The daily average soil temperature on a typical sunny day in autumn and winter increased in the order of 10 cm<20 cm<40 cm, and it decreased in the order of 10 cm>20 cm>40 cm in spring and summer. There was no significant difference of relative humidity in each month, growing seasons and the whole year between 50 cm and 150 cm height. (3) In the same climatic zone, the microclimate was greatly affected by topography, altitude and soil type. The higher the gravel content was, the higher the temperature was; the higher the altitude was, the lower the humidity and the greater the wind speed were. precipitation during the growing season was most at Liushi Winery with a lower altitude in front of the mountain, and it was least at Hennessy Winery. (4) The precipitation, air relative humidity and photosynthetic active radiation gradually decreased, and the temperature gradually increased from south to north in five small winery regions in east foothills region of Helan Mountain.
Based on the monthly maximum frozen soil depth at 68 meteorological stations in Shanxi Province during 1960-2018, the temporal and spatial distribution characteristics of the annual maximum frozen soil depth in Shanxi were studied by using EOF and wavelet analysis methods. The results are as follows: (1) The average annual maximum frozen soil depth at 68 stations in Shanxi during 1960-2018 was 71 cm, the extremely maximum value was 192 cm, and the extremely minimum value was 7 cm. In the past 59 years, the average annual maximum frozen soil depth at 68 stations in Shanxi showed a significantly decreasing trend with a climate tendency rate of -1.394 cm per decade, and it mutated in 1986. (2) The quasi-4-year period of average annual maximum frozen soil depth at 68 stations in Shanxi was detected. (3) The annual maximum frozen soil depth showed a spatial distribution characteristics with shallow in southern and deep in northern Shanxi, shallow in eastern and deep in western Shanxi. (4) The accumulated variance contribution rate of the first two modes of the annual maximum frozen soil depth in Shanxi reached 58.4%. The spatial pattern of the first mode was consistent in the whole province, while that of the second mode was reverse in southern and northern Shanxi.
Dew is an important part of vineyard water cycle, which plays a vital role in the regulation of vineyard microclimate, and it is also a necessary condition for the germination of microbial spores. Based on the hourly meteorological observation data during the growing period of wine grape from April to October at Yinchuan agro-meteorological station from 2003 to 2020 and microclimate station of Meiyu Chateau from 2019 to 2020 and the 10-minute leaf surface temperature data from a typical winery in the same area in June 2019, the leaf temperature and air temperature were compared, firstly. When the dewing temperature was less than leaf surface temperature, the dew occurred. Taking the vineyard of Meiyu Chateau as an example, the temporal variation characteristics of dewing temperature, dewing days, dewing duration and dewing time during the growing period of grape and its influencing factors in vineyards of eastern Helan Mountain area were analyzed. The results show that the monthly dewing temperature from April to October appeared single-peak pattern in vineyards of eastern Helan Mountain area, and it reached the peak in July and the minimum in October. In the past 18 years, the monthly dewing days and duration increased gradually during the growing period, and it was the most (longest) in September, while it was the least (shortest) in April, and their inter-annual changes were obvious. Dewing could occur in the whole day, but it mainly occurred from 17:00 to next 01:00, and the range of dewing time gradually increased from April to October, it was the widest in September and the narrowest in April. The dew point temperature was significantly positive correlated with the minimum temperature and precipitation, the dewing usually occurred before and after rainfall processes and under the low minimum temperature weathers. The pests and diseases had a closely relation with dewing, so when temperature was higher in the evening in September and October, the drying and ventilating was very important for preventing pests and diseases in the vineyard.
Based on observations of sunshine hours，cloud amount，wind speed and other meteorological elements during 1961－2009 in Shuozhou，the annual，seasonal and monthly variation of sunshine hours and its influencing factors were analyzed in this paper．The results indicated that the annual sunshine hours presented obvious ecreasing trend with－118．1 h/10 a tendency rate，and this phenomena started in 1980 and after 1990 it was more obvious．The seasonal sunshine hours also presented decrease trend，especially in summer．And monthly variation of sunshine hours also decreased especially in May．The annual wind speed in Shuozhou also reduced in recent 50 years especially after 1990．The air pollution increased after 1990 and annual wind speed reduction in Shuozhou may be the important reason for sunshine hours reduction in these years．
The different level rainy days and its homologous precipitation quantity are obtained by using the daily precipitation data from May to September ( 1960 － 2004) of 17 stations in the Qilian Mountain area，thus，we know the daily precipitation intensity of light rainfall and moderate rainfall( and more) at each station． Based on regional mean value of the different level rainy days and rainfall intensity in Qilian Mountain area，the tendency of the different level rainy days and rainfall intensity was analyzed using linear trend coefficient and 5 levels main value function． The results show that both precipitation and different level rainy days from May to September in Qilian Mountain area presented more in the west side and less in the east side in the same latitude area，and more in the east and less in the west part of Qilian Mountain． In recent 45 years，the light rainfall days was descending，but the moderate rainfall days was ascending． The precipitation intensity of light rainfall and moderate rainfall ( and more) presented ascending trend too from May to September in Qilian Mountain area． The morlet wave analysis show that the light rainfall days had a period of five years，but the period of the moderate rainfall ( and more) days was more complex．
Based on analysis of circulation background, influencing system and the characteristics of physical quantity fields on each layer, the diagnostic analysiswas performed on theweatherprocess of the snowstorm happened inTangshanRegion during3 to4March in 2007 by usingMICAPS data and NCEP 1°×1°6-hour interval reanalyzed data. The results are as follows: the deepening upper trough, the vortex at700 hPa layer and the intensive cold airweremain influencing systems that cause the snowstorm weatherprocess;the divergence athigh level and convergence at low leve,l the enhanced positive vortex, the strong ascendingmotion and thewarm air forced to liftby cold airwere the importantdynamicmechanism of thisweatherevent; the vapour transportcame from the deflection east airstream at the low layer; and theQ-vector convergence at700 hPa correlated to the area of snowstorm’s occurrence, which can be used as an indicator in forecasting snowstorm weather.
Based on meteorological observations such as pan evaporation, temperature, sunshine hours,wind speed, humidity during 1956-2005 in Shuozhou ofShanxiProvince, the annua,l monthly and seasonalvariation ofevaporation in Shuozhouwas analyzed in detai,l and the influence factors of evaporation were also discussed. Results show that the evaporation presented an obvious downward trend in recent50 years in Shouzhou, especially in spring and summer, and decreasing trendwasmost remarkable inMay; Therewas obviously positive correlation between evaporation and sunshine hours, mean wind speed, mean temperature daily range, but negative correlation between evaporation and relative humidity, vapor pressure, which indicated that sunshine hours, mean wind speed, mean temperature daily range, relative humidity and vaporpressureweremain factors resulted in evaporation decrease in Shouzhou of Shanxi Province.
Measurements of dew were carried out on four different soil surfaces ( biological soil crust, physical soil crust, bare sand and imp roved sandy soil) and different locationswithin a dune inMu us SandyLand in August 2007. Moreover, the p rocess of dew formation within a day was also observed. The results indicated that the characteristic of particle size was a determining factor for the dew amount for the different soil surfaces, the imp roved sandy soil had highest dew amount because it had a higher content of silt, and the dew amount of biological crust is significant higher than that of the bare dune sand. In general, dew begins at 17: 00 and ends at 7: 00,which correlated with the land surface temperature, the difference between air temperature and land surface temperture, net radiation on an hour time scale, and temperature daily range. The dew amount also changes with different locations of a dune, the dew amount in the top of the dune is least ( 0. 066 mm) , andmost (0. 100 mm) in foot slope of the dune, the resultmay relate to the sun radiation.
Using daily p recip itation data in 59 stations of Gansu p rovince during 1960 - 2006, extremely heavy p recip itation thresholds are determined for different stations, and the temporal and spatial distribution of summer extremely heavy p recip itation is diagnosed in recent half century. The results show that the consistent anomaly distribution is main spatial mode for summer heavy p recip itation in Gansu p rovince, and the spatialmode is divided into five key areas: the Longnan area, the Longzhong area, the west of Hexi area, the east of Hexi and the Longdong area, respectively. The extremely heavy p recip itation p resented decreasing tendency in the Longnan and Longzhong areas, and increasing tendency in the east of Hexi and Longdong areas, but it came through few - more - few change in the west of Hexi area. From period analysis, the period vibration of 11 - 13 a and 6 - 8 a disp layed clearly in most key areas.
The yearly rainy days with different rainfall level and annual precipitation were obtained by using the daily precipitation data (1960-2004) of 17 stations in the Qilian Mountain. By means of EOF and REOF analysis on normalized annual precipitation, the abnormal spatial distribution and the time evolvement of annual precipitation there were investigated. Results show that the climate average distributions of annual precipitation and different level rainy days were similarity in geographical distribution. Both the annual precipitation and the different level rainy days were evidently more in the west side than that in the east side of the same latitude area, and more in the east section than that in the west section of the Qilian Mountain, and the isoline presented the direction of northwest to southeast. The spatial anomaly of the annual precipitation characterized the coincident variability in the whole area at first, and then the adverse trends in the east and the west part. The rotated loading vectors reflected 4 anomaly modes of the north slope of the west section, the east section, the south slope of the west and middle section, and the north slope of the middle section of the Qilian Mountain. In recent 45 years, the decadal change in precipitation was obvious in the north slope of the west section and relatively small in the other three areas. Wavelet analysis shows that the precipitation period changes were different in four areas, and that means the complexity of the annual total precipitation over the Qilian Mountain.
