To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined w...To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined with dust storm frequency data, and the possible impacts of meteorological and anthropogenic factors on dust storm frequency were analyzed by using regression analysis and PCA (Principal Component Analysis). Results show that the inter-annual dust storm frequency increased gradually. In particular, an increasing trend in recent years, after 2009, is conspicuous. The monthly frequency of dust storms shows higher values between the months of February and May, with the highest mean number of events occurring in April, which accounts for 29% of the annual dust storm frequency. The annual dust storm frequency is positively correlated with wind speed and negatively correlated with precipitation;the monthly dust storm frequency is positively correlated with wind speed, but no significant correlation can be found with precipitation. The relationship between temperature and dust storms is not simply linear, however, a certain correlation with an unremarkable statistical significance can be found between them. Human activities also affect the dynamics of dust storms indirectly via changing vegetation coverage and direct dust emissions. The multivariate analysis further confirmed the association between dust storm frequency and meteorological factors and NDVI. The high loadings of dust storm frequency, wind speed, precipitation and NDVI on a PC indicate that the increased precipitation and NDVI will decrease dust storm frequency, and increased wind speed will increase dust storm frequency.展开更多
This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oi...This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oil/gas in China as of 2020 based on statistics.As shown by the results,the proved oil initially-in-place(OIIP),the proved undeveloped OIIP,and the remaining proved TRR of oil in China are mainly distributed in the Bohai Bay,Ordos and Songliao Basins,and those of free gas are mainly in the Ordos,Sichuan,and Tarim Basins.From 2011 to 2020,the largest increment in the proved OIIP,the proved undeveloped OIIP and the remaining proved TRR of oil occurred in the Ordos Basin,followed by the Bohai Bay Basin,while that in the proved gas initially-in-place(GIIP),the proved undeveloped GIIP,and the remaining proved TRR of gas occurred in the Ordos Basin,followed by the Sichuan Basin.In addition,a comprehensive analysis reveals that the petroliferous basins in China with the potential of reserve addition and production growth include the Ordos Basin,the Bohai Bay Basin,the Sichuan Basin,and the Tarim Basin.展开更多
[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on ...[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on the daily minimum surface temperature data in 67 meteorological observatories of Shandong Province during 1961-2008, the variation characteristics of first, last frost dates and frost-free period in Shandong Province were analyzed by using the climate diagnosis analysis method. [Result] The climate characteristics of first, last frost dates and frost-free period had the obvious geographical differences in Shandong Province in recent 48 years. The extreme differences of first, last frost dates and frost-free period were all above the three times of their standard deviations. It illustrated that the dispersion degrees of first, last dates and frost-free period were all very big. The average first frost date postponed with 1.99 d/10 a velocity in Shandong Province in recent 48 years, and the last frost date advanced with 1.46 d/10 a velocity. The postponing range of first frost date was bigger than the advancing range of last frost date, and the frost-free period prolonged with 3.42 d/10 a velocity. Seen from the interdecadal variations, the first frost date started to obviously postpone, and the last frost date obviously advanced since the 1990s. The frost-free period also started to obviously prolong since the 1990s. [Conclusion] The research provided the certain reference for the predication, prevention of frost disaster and the structure adjustment of crops.展开更多
[Objective] The research aimed to study the variation of rainfall data from Guilin Weather Station during 1957-2007.[Method] Based on the daily rainfall data in Guilin during 1957-2007,the trend,period and mutation of...[Objective] The research aimed to study the variation of rainfall data from Guilin Weather Station during 1957-2007.[Method] Based on the daily rainfall data in Guilin during 1957-2007,the trend,period and mutation of precipitation in Guilin in 51 years were analyzed by using the trend analysis,wavelet analysis and Mann-Kendall non-parameter statistics test method.[Result] The rainfall in Guilin in 51 years presented the rising trend.The rainfall variation was same in the first,second and third quarters of most years,except in the individual year.The rainfall in the fourth quarter had the decrease trend,and the variation was obvious in each year.It illustrated that the rainfall variation in winter was very unstable and had the decrease trend in recent years.But as a whole,the variation of total rainfall in Guilin wasn't obvious and had the rise trend.It illustrated that the climate variation in Guilin in 51 years wasn't obvious.The wavelet analysis showed that the rainfall variation in Guilin had 15-year big period and the small period of 2-3 years.Mann-Kendall non-parameter statistics test showed that the mutation situation of total rainfall in Guilin in 51 years wasn't obvious.But the mutation situations in the second and third quarters were more.The variation in recent 10 years was the most obvious.Maybe it was affected by the global climate variation.[Conclusion] The research provided the theory basis for analyzing the climate variation in Guilin.展开更多
By using the daily temperature data in 90 meteorological observatories in Shandong Province,the median and a new kind of extreme event detection method which was put forward by Hample,the variation characteristics of ...By using the daily temperature data in 90 meteorological observatories in Shandong Province,the median and a new kind of extreme event detection method which was put forward by Hample,the variation characteristics of extreme cold and warm weather climate events in Shandong Province were detected and analyzed.The results showed that the extreme high temperature days had no obvious variation,and the extreme warm days tended to increase.The extreme cold event decreased obviously and had the obvious inter-decadal variation characteristic.In the 1960s,the extreme cold(warm) event happened frequently,but they both decreased slightly during the 1970s-metaphase of 1980s.After the metaphase of 1990s,the extreme warm event happened frequently,but the extreme cold event decreased sharply.In the spatial distribution,the extreme cold events in most areas of Shandong tended to decrease.But the occurrence frequency variation of extreme warm event presented the radial distribution characteristics that it increased in the eastern coastal zone and decreased in the southwest,northwest of Shandong Province.Under the background that the global climate became warm obviously in the metaphase of 1980s,the positive trend scope of extreme warm event linear variation in Shandong Province obviously became large.The variation of extreme low temperature days in most areas tended to be stable,and the main trend of extreme cold days was still the rapid decrease.展开更多
[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological station...[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological stations (Guyuan, Xiji, Jingyuan, Longde, Liupanshan) in the south of Ningxia during 1960-2009, the spatial distribution rule, the interannual and monthly climatic characteristics and variation trends of hail in the south mountain area of Ningxia were analyzed by using the statistical method. Moreover, the hail disaster prevention and reduction measures in Guyuan were put forward. [Result] The hail in the south mountain area of Ningxia in recent 50 years had the obvious annual, seasonal, monthly and daily variation characteristics. The hail might occur from March to October and mainly concentrated during May-August which occupied 72% in the whole year. The occurrence probability of hail in June was the biggest and occupied 21.7% in the whole year. It was the typical multi-hail zone in summer. The interannual variation of hail occurrence in Guyuan was big and had 3-year periodicity. The secondary-order time trend of hail in Guyuan was the anti-parabolic type, and the hail occurrence times during the 1960s-1980s presented the increase trend. It was the hail multi-occurrence period in the 1970s and 1980s. After the 1990s, the hail presented the decrease trend. In recent 20 years, the hail significantly decreased. The hail in Guyuan mainly concentrated during 12:00-21:00, and the hail occurrence times occupied 85% of total times. The hail distribution in Guyuan area had the obvious regional characteristics. The hail in the mountain area, hilly area was more and in the stream valley, north Pingchuan area was less. The hail cloud mainly derived from the mountain areas, such as Liupanshan, Nanhua Mountain, Yueliang Mountain, Xifeng Mountain and Yunwu Mountain, etc. The move direction of hail cloud was mainly from northwest to southeast or from north to south. Part of hail cloud disappeared in the original place. According to the regional distribution of hail, the hail risk in Guyuan City was divided into the high, moderate and low occurrence zones by combining with the hail disaster data. [Conclusion] The research provided the scientific basis for the forecast, early-warning of hail weather and the artificial hail suppression.展开更多
[Objective] The aim was to study the change characteristics of temperature and heat resources in rural area of Chaoyang in western Liaoning. [Method] Based on the data from rural meteorological station in Chaoyang in ...[Objective] The aim was to study the change characteristics of temperature and heat resources in rural area of Chaoyang in western Liaoning. [Method] Based on the data from rural meteorological station in Chaoyang in western Liaoning from 1966 to 2010, the change characteristics of temperature and heat resources in rural area in Chaoyang were analyzed by means of serial correlation and climate tendency method, so as to master its climate situation. [Result] The annual average value of daily average temperature, daily maximum temperature and daily minimum temperature in rural area of Chaoyang in western Liaoning from 1966 to 2010 showed fluctuation variation, and the annual average value of daily maximum temperature increased most obviously with the climatic tendency of 0.328 ℃/10 a and highest significant level, so it played an important role in temperature increase, next came daily average temperature (0.151 ℃/10 a), while there was no obvious decrease in daily minimum temperature. The average of daily maximum temperature in winter half year increased more obviously than that in summer half year, with the climatic tendency of 0.417 and 0.250 ℃/10 a, respectively; the trend of daily average temperature reached low significant level, and there was no obvious variation in daily minimum temperature. In addition, ≥10 ℃ accumulated temperature in rural area of Chaoyang in western Liaoning went up obviously, with the climatic tendency of 42.59 ℃·d/10 a, namely it increased by 192 ℃·d in recent 45 years. [Conclusion] The study could provide climatic reference for the adjustment of agriculture structure and varieties distribution.展开更多
[Objective] The research aimed to study the influence of climate warming on the agriculture in Shenbei New District of Shenyang in recent 38 years.[Method] Based on the temperature data in Shenbei New District of Shen...[Objective] The research aimed to study the influence of climate warming on the agriculture in Shenbei New District of Shenyang in recent 38 years.[Method] Based on the temperature data in Shenbei New District of Shenyang during 1971-2008,by using the conventional statistical method,the variation trends of temperature and active accumulated temperature in Shenbei New District under the climate warming environment were analyzed,and the influence of climate warming on the agriculture was discussed.[Result] The annual average temperature,annual average maximum temperature,annual averageminimum temperature and ≥ 0℃,≥ 10℃ active accumulated temperatures which were passed stably in Shenbei New District in recent 38 years all showed the obvious rising trend.The climate tendency rates were respectively 0.4,0.3,0.1℃/10 a and 79.1,76.7℃·d/10 a.They all showed the declining trend in the coldest December,January and the rising trend in other months.The rising range of maximum temperature was bigger than that ofminimum temperature,and the rising range in summer was bigger than that in winter.The analysis result was different from that of many scholars.When the temperatures rose,and the heat resources increased,the agricultural cropping index improved,and the cultivated boundary of mid-late maturity variety moved northward.The industrialized agriculture developed quickly.Meanwhile,the risks of drought and flood disasters increased,and the insect pest aggravated.[Conclusion] The research provided the scientific basis for improving the cognizance about the influence of climate warming on the agricultural production and strengthening the strain capacity of local agricultural production adapting the climate variation.展开更多
In order to know how regional averaged cloud top height(CTH)responded to the past climatic change,the spatial and temporal variations of CTH based on MODIS data(MOD03_08_v6.0)from March 2000 to February 2018 are analy...In order to know how regional averaged cloud top height(CTH)responded to the past climatic change,the spatial and temporal variations of CTH based on MODIS data(MOD03_08_v6.0)from March 2000 to February 2018 are analyzed.The results show that the CTH in East Asia was higher in the southwest and lower in the northeast.The annual mean CTH was found to increase in East Asia at the rate of 0.020 km per year,of which,0.035 km per year over the eastern land and 0.034 km per year over the eastern sea.The CTH changes statistically correlated with the sea surface temperature changes over the eastern sea(r=0.68),which indicates that the CTH changes may be affected by the underlying surface.Statistically significant increasing trend of annual mean CTH was found in the latitude zone of 30°–40°N.Furthermore,CTH showed decreasing trends of about−0.030 km per year in the Middle-Lower Yangtze River Basin,Tarim Basin,Turpan Basin and northeastern Sichuan Basin in summer since more low cloud formations benefited to the decrease of CTH.In winter,the decreasing trend of CTH was found over the north of 40°N,whereas the increasing trend was found over the south of 40°N in East Asia.展开更多
文摘To reveal the multivariate relationships between man-made and meteorological factors on dust storm frequency, the LUCC data, NDVI remote sensing data and meteorological data for the period of 1983-2013 were combined with dust storm frequency data, and the possible impacts of meteorological and anthropogenic factors on dust storm frequency were analyzed by using regression analysis and PCA (Principal Component Analysis). Results show that the inter-annual dust storm frequency increased gradually. In particular, an increasing trend in recent years, after 2009, is conspicuous. The monthly frequency of dust storms shows higher values between the months of February and May, with the highest mean number of events occurring in April, which accounts for 29% of the annual dust storm frequency. The annual dust storm frequency is positively correlated with wind speed and negatively correlated with precipitation;the monthly dust storm frequency is positively correlated with wind speed, but no significant correlation can be found with precipitation. The relationship between temperature and dust storms is not simply linear, however, a certain correlation with an unremarkable statistical significance can be found between them. Human activities also affect the dynamics of dust storms indirectly via changing vegetation coverage and direct dust emissions. The multivariate analysis further confirmed the association between dust storm frequency and meteorological factors and NDVI. The high loadings of dust storm frequency, wind speed, precipitation and NDVI on a PC indicate that the increased precipitation and NDVI will decrease dust storm frequency, and increased wind speed will increase dust storm frequency.
文摘This study analyzes the status-quo of the proved oil/gas initially-in-place and its variation trend,the proved undeveloped oil/gas initially-in-place,and the remaining proved technically recoverable reserves(TRR)of oil/gas in China as of 2020 based on statistics.As shown by the results,the proved oil initially-in-place(OIIP),the proved undeveloped OIIP,and the remaining proved TRR of oil in China are mainly distributed in the Bohai Bay,Ordos and Songliao Basins,and those of free gas are mainly in the Ordos,Sichuan,and Tarim Basins.From 2011 to 2020,the largest increment in the proved OIIP,the proved undeveloped OIIP and the remaining proved TRR of oil occurred in the Ordos Basin,followed by the Bohai Bay Basin,while that in the proved gas initially-in-place(GIIP),the proved undeveloped GIIP,and the remaining proved TRR of gas occurred in the Ordos Basin,followed by the Sichuan Basin.In addition,a comprehensive analysis reveals that the petroliferous basins in China with the potential of reserve addition and production growth include the Ordos Basin,the Bohai Bay Basin,the Sichuan Basin,and the Tarim Basin.
文摘[Objective] The research aimed to study the climate variation characteristics of frost in Shandong Province. [Method] The daily minimum surface temperature ≤ 0 ℃ in autumn or spring was as the frost index. Based on the daily minimum surface temperature data in 67 meteorological observatories of Shandong Province during 1961-2008, the variation characteristics of first, last frost dates and frost-free period in Shandong Province were analyzed by using the climate diagnosis analysis method. [Result] The climate characteristics of first, last frost dates and frost-free period had the obvious geographical differences in Shandong Province in recent 48 years. The extreme differences of first, last frost dates and frost-free period were all above the three times of their standard deviations. It illustrated that the dispersion degrees of first, last dates and frost-free period were all very big. The average first frost date postponed with 1.99 d/10 a velocity in Shandong Province in recent 48 years, and the last frost date advanced with 1.46 d/10 a velocity. The postponing range of first frost date was bigger than the advancing range of last frost date, and the frost-free period prolonged with 3.42 d/10 a velocity. Seen from the interdecadal variations, the first frost date started to obviously postpone, and the last frost date obviously advanced since the 1990s. The frost-free period also started to obviously prolong since the 1990s. [Conclusion] The research provided the certain reference for the predication, prevention of frost disaster and the structure adjustment of crops.
基金Supported by Guangxi Scientific and Technological Project(Guikegong 0816006-10)Scientific Research Item of Guangxi Science and Technology Agency(Guikeneng 0801Z004)
文摘[Objective] The research aimed to study the variation of rainfall data from Guilin Weather Station during 1957-2007.[Method] Based on the daily rainfall data in Guilin during 1957-2007,the trend,period and mutation of precipitation in Guilin in 51 years were analyzed by using the trend analysis,wavelet analysis and Mann-Kendall non-parameter statistics test method.[Result] The rainfall in Guilin in 51 years presented the rising trend.The rainfall variation was same in the first,second and third quarters of most years,except in the individual year.The rainfall in the fourth quarter had the decrease trend,and the variation was obvious in each year.It illustrated that the rainfall variation in winter was very unstable and had the decrease trend in recent years.But as a whole,the variation of total rainfall in Guilin wasn't obvious and had the rise trend.It illustrated that the climate variation in Guilin in 51 years wasn't obvious.The wavelet analysis showed that the rainfall variation in Guilin had 15-year big period and the small period of 2-3 years.Mann-Kendall non-parameter statistics test showed that the mutation situation of total rainfall in Guilin in 51 years wasn't obvious.But the mutation situations in the second and third quarters were more.The variation in recent 10 years was the most obvious.Maybe it was affected by the global climate variation.[Conclusion] The research provided the theory basis for analyzing the climate variation in Guilin.
文摘By using the daily temperature data in 90 meteorological observatories in Shandong Province,the median and a new kind of extreme event detection method which was put forward by Hample,the variation characteristics of extreme cold and warm weather climate events in Shandong Province were detected and analyzed.The results showed that the extreme high temperature days had no obvious variation,and the extreme warm days tended to increase.The extreme cold event decreased obviously and had the obvious inter-decadal variation characteristic.In the 1960s,the extreme cold(warm) event happened frequently,but they both decreased slightly during the 1970s-metaphase of 1980s.After the metaphase of 1990s,the extreme warm event happened frequently,but the extreme cold event decreased sharply.In the spatial distribution,the extreme cold events in most areas of Shandong tended to decrease.But the occurrence frequency variation of extreme warm event presented the radial distribution characteristics that it increased in the eastern coastal zone and decreased in the southwest,northwest of Shandong Province.Under the background that the global climate became warm obviously in the metaphase of 1980s,the positive trend scope of extreme warm event linear variation in Shandong Province obviously became large.The variation of extreme low temperature days in most areas tended to be stable,and the main trend of extreme cold days was still the rapid decrease.
文摘[Objective] The research aimed to study the climatic characteristics of hail in the southern mountain area of Ningxia in recent 50 years. [Method] Based on the hail observation data of 5 surface meteorological stations (Guyuan, Xiji, Jingyuan, Longde, Liupanshan) in the south of Ningxia during 1960-2009, the spatial distribution rule, the interannual and monthly climatic characteristics and variation trends of hail in the south mountain area of Ningxia were analyzed by using the statistical method. Moreover, the hail disaster prevention and reduction measures in Guyuan were put forward. [Result] The hail in the south mountain area of Ningxia in recent 50 years had the obvious annual, seasonal, monthly and daily variation characteristics. The hail might occur from March to October and mainly concentrated during May-August which occupied 72% in the whole year. The occurrence probability of hail in June was the biggest and occupied 21.7% in the whole year. It was the typical multi-hail zone in summer. The interannual variation of hail occurrence in Guyuan was big and had 3-year periodicity. The secondary-order time trend of hail in Guyuan was the anti-parabolic type, and the hail occurrence times during the 1960s-1980s presented the increase trend. It was the hail multi-occurrence period in the 1970s and 1980s. After the 1990s, the hail presented the decrease trend. In recent 20 years, the hail significantly decreased. The hail in Guyuan mainly concentrated during 12:00-21:00, and the hail occurrence times occupied 85% of total times. The hail distribution in Guyuan area had the obvious regional characteristics. The hail in the mountain area, hilly area was more and in the stream valley, north Pingchuan area was less. The hail cloud mainly derived from the mountain areas, such as Liupanshan, Nanhua Mountain, Yueliang Mountain, Xifeng Mountain and Yunwu Mountain, etc. The move direction of hail cloud was mainly from northwest to southeast or from north to south. Part of hail cloud disappeared in the original place. According to the regional distribution of hail, the hail risk in Guyuan City was divided into the high, moderate and low occurrence zones by combining with the hail disaster data. [Conclusion] The research provided the scientific basis for the forecast, early-warning of hail weather and the artificial hail suppression.
基金Supported by Natural Science Foundation of Liaoning Province(20102109)
文摘[Objective] The aim was to study the change characteristics of temperature and heat resources in rural area of Chaoyang in western Liaoning. [Method] Based on the data from rural meteorological station in Chaoyang in western Liaoning from 1966 to 2010, the change characteristics of temperature and heat resources in rural area in Chaoyang were analyzed by means of serial correlation and climate tendency method, so as to master its climate situation. [Result] The annual average value of daily average temperature, daily maximum temperature and daily minimum temperature in rural area of Chaoyang in western Liaoning from 1966 to 2010 showed fluctuation variation, and the annual average value of daily maximum temperature increased most obviously with the climatic tendency of 0.328 ℃/10 a and highest significant level, so it played an important role in temperature increase, next came daily average temperature (0.151 ℃/10 a), while there was no obvious decrease in daily minimum temperature. The average of daily maximum temperature in winter half year increased more obviously than that in summer half year, with the climatic tendency of 0.417 and 0.250 ℃/10 a, respectively; the trend of daily average temperature reached low significant level, and there was no obvious variation in daily minimum temperature. In addition, ≥10 ℃ accumulated temperature in rural area of Chaoyang in western Liaoning went up obviously, with the climatic tendency of 42.59 ℃·d/10 a, namely it increased by 192 ℃·d in recent 45 years. [Conclusion] The study could provide climatic reference for the adjustment of agriculture structure and varieties distribution.
文摘[Objective] The research aimed to study the influence of climate warming on the agriculture in Shenbei New District of Shenyang in recent 38 years.[Method] Based on the temperature data in Shenbei New District of Shenyang during 1971-2008,by using the conventional statistical method,the variation trends of temperature and active accumulated temperature in Shenbei New District under the climate warming environment were analyzed,and the influence of climate warming on the agriculture was discussed.[Result] The annual average temperature,annual average maximum temperature,annual averageminimum temperature and ≥ 0℃,≥ 10℃ active accumulated temperatures which were passed stably in Shenbei New District in recent 38 years all showed the obvious rising trend.The climate tendency rates were respectively 0.4,0.3,0.1℃/10 a and 79.1,76.7℃·d/10 a.They all showed the declining trend in the coldest December,January and the rising trend in other months.The rising range of maximum temperature was bigger than that ofminimum temperature,and the rising range in summer was bigger than that in winter.The analysis result was different from that of many scholars.When the temperatures rose,and the heat resources increased,the agricultural cropping index improved,and the cultivated boundary of mid-late maturity variety moved northward.The industrialized agriculture developed quickly.Meanwhile,the risks of drought and flood disasters increased,and the insect pest aggravated.[Conclusion] The research provided the scientific basis for improving the cognizance about the influence of climate warming on the agricultural production and strengthening the strain capacity of local agricultural production adapting the climate variation.
基金This work was financially supported by the National Key Research and Development Program of China(2017YFA0603502)the(Key)National Natural Science Foundation of China(91644211,41575002)the Public Meteorology Special Foundation of MOST(GYHY201406023)。
文摘In order to know how regional averaged cloud top height(CTH)responded to the past climatic change,the spatial and temporal variations of CTH based on MODIS data(MOD03_08_v6.0)from March 2000 to February 2018 are analyzed.The results show that the CTH in East Asia was higher in the southwest and lower in the northeast.The annual mean CTH was found to increase in East Asia at the rate of 0.020 km per year,of which,0.035 km per year over the eastern land and 0.034 km per year over the eastern sea.The CTH changes statistically correlated with the sea surface temperature changes over the eastern sea(r=0.68),which indicates that the CTH changes may be affected by the underlying surface.Statistically significant increasing trend of annual mean CTH was found in the latitude zone of 30°–40°N.Furthermore,CTH showed decreasing trends of about−0.030 km per year in the Middle-Lower Yangtze River Basin,Tarim Basin,Turpan Basin and northeastern Sichuan Basin in summer since more low cloud formations benefited to the decrease of CTH.In winter,the decreasing trend of CTH was found over the north of 40°N,whereas the increasing trend was found over the south of 40°N in East Asia.
