The surface vapor content has a close correlation with the generation of precipitation. Based on the atmospheric circulation data and surface vapor content data from 37 weather stations across the Tarim Basin dur- ing...The surface vapor content has a close correlation with the generation of precipitation. Based on the atmospheric circulation data and surface vapor content data from 37 weather stations across the Tarim Basin dur- ing 1961-2010, the paper analyzed the vapor variation trend, period, abrupt changes and their causes. The results show that the increase trend of surface vapor content over the Tarim Basin mostly conforms with the average trend coefficient of 0.48. There were 3 centers displaying a trend of high vapor increase and 3 centers displaying a low vapor increase. These centers were distributed in strips and blocks across the basin from northeast to southwest. Notable inter-decadal variations in annual and seasonal vapor contents occurred in the Tarim Basin during the 50 years of the study period, with more vapor after the mid-1980s and less vapor in the 1960s and the 1970s. The significant increase in vapor content in the 50 year period occurred mostly in the 1980s and the 1990s. The in- creasing trend across the four seasons was strongest in summer, reaching 0.43, and weakest in spring. Great variations existed between the spring trend and the annual, summer, autumn and winter trends. During the 50-year study period, there are distinguishable periods of 4-6 years and 8-10 years in which the annual and seasonal vapor contents varied alternately between low and high concentrations. The annual vapor content and that of the four individual seasons all changed abruptly in about the mid-1980s （a〈0.05）. The west wind circulation, Tibetan Plateau circulation and the annual mean temperatures of the Tarim Basin are the main factors that influenced the surface vapor content over the study area, of which the Tibetan Plateau circulation may be the most important one.展开更多
Based on the climate factors data and surface vapor pressure （SVP） data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content （WVC） estimation model ...Based on the climate factors data and surface vapor pressure （SVP） data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content （WVC） estimation model according to the relationship between monthly WVC of radiosonde and corresponding SVP and analyzes the spatial and temporal variability of WVC and their causes. The results show that the WVC is linearly and negatively related to the elevation and longitude （Vertical zonality and Longitude zonality）, while it was not linearly related to the latitude. The westerly wind, geographical situation and sea level elevation composed complex surface conditions to influence the spatial distribution of WVC in the Tianshan Mountains. The Mann-Kendall （M-K） statistical test shows a significant increasing trend in the mean annual WVC in Tianshan Mountains during 1961- 2011（P 〈 0.001）, with a rate of 0.23 mm/decade, and indicates an abrupt turning point in 1985 （P.〈0.001）. Correlation analysis shows that the WVC are significantly correlated to the temperature, especially during the winter, but the summer WVC are significantly correlated to the precipitation. In addition, the North Atlantic Oscillation Index （NAOI） and the Arctic Oscillation Index （AOI） are significantly correlated to the winter WVC in the Tianshan Mountains. As a new Microwave radiometric profilers （MWRPs） instrument, the MP- 3000A provides continuous, real-time and high temporal resolution atmospheric profiles up to 10 km. In order to monitor water vapor and atmosphere profiles in Tianshan Mountains, an MP-3000A was established in Urumqi （43.8°N, 87.58°N） in May 2008. The results indicated that the MP-3oooA was applicable to this area, and the evolutionary process of water vapor and the WVC peak values of MP- 3000A were a strong signal for rainstorm and flood forecasts for Urumqi and the Tianshan Mountains.展开更多
Water vapor in the earth′s upper atmosphere plays a crucial role in the radiative balance, hydrological process, and climate change. Based on the latest moderate-resolution imaging spectroradiometer(MODIS) data, this...Water vapor in the earth′s upper atmosphere plays a crucial role in the radiative balance, hydrological process, and climate change. Based on the latest moderate-resolution imaging spectroradiometer(MODIS) data, this study probes the spatio-temporal variations of global water vapor content in the past decade. It is found that overall the global water vapor content declined from 2003 to 2012(slope b = –0.0149, R = 0.893, P = 0.0005). The decreasing trend over the ocean surface(b = –0.0170, R = 0.908, P = 0.0003) is more explicit than that over terrestrial surface(b = –0.0100, R = 0.782, P = 0.0070), more significant over the Northern Hemisphere(b = –0.0175, R = 0.923, P = 0.0001) than that over the Southern Hemisphere(b = –0.0123, R = 0.826, P = 0.0030). In addition, the analytical results indicate that water vapor content are decreasing obviously between latitude of 36°N and 36°S(b = 0.0224, R = 0.892, P = 0.0005), especially between latitude of 0°N and 36°N(b = 0.0263, R = 0.931, P = 0.0001), while the water vapor concentrations are increasing slightly in the Arctic regions(b = 0.0028, R = 0.612, P = 0.0590). The decreasing and spatial variation of water vapor content regulates the effects of carbon dioxide which is the main reason of the trend in global surface temperatures becoming nearly flat since the late 1990 s. The spatio-temporal variations of water vapor content also affect the growth and spatial distribution of global vegetation which also regulates the global surface temperature change, and the climate change is mainly caused by the earth's orbit position in the solar and galaxy system. A big data model based on gravitational-magmatic change with the solar or the galactic system is proposed to be built for analyzing how the earth's orbit position in the solar and galaxy system affects spatio-temporal variations of global water vapor content, vegetation and temperature at large spatio-temporal scale. This comprehensive examination of water vapor changes promises a holistic understanding of the global climate change and potential underlying mechanisms.展开更多
Spatial and temporal resolution of water vapor content is useful in improving the accuracy of short_term weather prediction.Dense and continuously tracking regional GPS arrays will play an important role in remote sen...Spatial and temporal resolution of water vapor content is useful in improving the accuracy of short_term weather prediction.Dense and continuously tracking regional GPS arrays will play an important role in remote sensing atmospheric water vapor content.In this study,a piecewise linear solution method was proposed to estimate the precipitable water vapor (PWV) content from ground_based GPS observations in Hong Kong.To evaluate the solution accuracy of the water vapor content sensed by GPS,the upper air sounding data (radiosonde) that are collected locally was used to calculate the precipitable water vapor during the same period.One_month results of PWV from both ground_based GPS sensing technique and radiosonde method are in agreement within 1～2 mm.This encouraging result will motivate the GPS meteorology application based on the establishment of a dense GPS array in Hong Kong.展开更多
Water vapor content in the atmosphere is very significant for atmospheric correction of optical remote sensing data. Nowadays, the common atmospheric correction models use a single value of the average water vapor con...Water vapor content in the atmosphere is very significant for atmospheric correction of optical remote sensing data. Nowadays, the common atmospheric correction models use a single value of the average water vapor content of the study area to perform atmospheric correction. As the distribution of water vapor content varies greatly with time and space, it is obviously inaccurate to represent the total water vapor conditions of the whole area by just reading the average water vapor content. In this study, we altered the 6S sources so that it could read the water vapor content image which was retrieved from MODIS 1 km data. Atmospheric correction was implemented for the band 1 of MODIS 500 m data pixel-by-pixel using the improved 6S model. In comparison with the traditional 6S model, this improved 6S model is more reasonable in atmospheric correction, for it considers the spatial distribution of the water vapor content retrieved from MODIS data in the near infrared to define the atmospheric conditions for simulating the atmospheric radiative transfer. The results corrected by the improved 6S model showed more reasonable in pixel spatial distribution and closer histogram with the original image than those by traditional 6S model.展开更多
The interannual and intermonthly climatic features of the water vapor content(hereafter WVC)and its mean transfer in the atmosphere over Northwest China(hereafter NWC)are calculated and analyzed by using the NCEP/NCAR...The interannual and intermonthly climatic features of the water vapor content(hereafter WVC)and its mean transfer in the atmosphere over Northwest China(hereafter NWC)are calculated and analyzed by using the NCEP/NCAR global reanalysis grid data(2.5°×2.5°Lat/Lon) for 40 years(1958—1997).The results show that the WVC in the total air column over NWC in four seasons of the year is mainly concentrated on eastern and western NWC respectively.On the average,the WVC over eastern NWC decreases obviously during recent forty years except for winter.while it decreases over western NWC in the whole year.But the WVC over NWC has been increasing since late 1980s in summer.The water vapor comes from the southwestern warm and wet air current along the Yarlung Zangbo River Valley and the Bay of Bengal.and from mid- western Tibetan Plateau and also from the Qinling Mountains at southern Shaanxi Province.The yearly water vapor divergence appears over the middle of NWC to northern Xinjiang and southeastern Shaanxi Province.The yearly water vapor convergence appears over the Tarim Basin and the Tibetan Plateau as well as western Sichuan and southern Gansu.展开更多
In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Ka...In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Karsten's model at Kolkata, a tropical location in the Indian region. Cloud liquid water contents (LWC) are obtained from these profiles which show a prominent seasonal variation. The monsoon months exhibit much higher values of LWC than in other months. However Salonen's model yields higher LWC values than that obtained with Karsten's model. The variation of daily total rainfall with LWC shows a positive relationship indicating the role of LWC in controlling the rainfall. Also the variation pattern of LWC with integrated water vapor (IWV) content of the atmosphere indicates that a threshold value of water vapor is required for cloud to form and once cloud is formed LWC increases with IWV.展开更多
基金supported by the National Natural Science Foundation of China (40975097)National Basic Research Program of China (2010CB951001)the Special Fund for Public Welfare Industry (Meteorology) (GYHY201006012)
文摘The surface vapor content has a close correlation with the generation of precipitation. Based on the atmospheric circulation data and surface vapor content data from 37 weather stations across the Tarim Basin dur- ing 1961-2010, the paper analyzed the vapor variation trend, period, abrupt changes and their causes. The results show that the increase trend of surface vapor content over the Tarim Basin mostly conforms with the average trend coefficient of 0.48. There were 3 centers displaying a trend of high vapor increase and 3 centers displaying a low vapor increase. These centers were distributed in strips and blocks across the basin from northeast to southwest. Notable inter-decadal variations in annual and seasonal vapor contents occurred in the Tarim Basin during the 50 years of the study period, with more vapor after the mid-1980s and less vapor in the 1960s and the 1970s. The significant increase in vapor content in the 50 year period occurred mostly in the 1980s and the 1990s. The in- creasing trend across the four seasons was strongest in summer, reaching 0.43, and weakest in spring. Great variations existed between the spring trend and the annual, summer, autumn and winter trends. During the 50-year study period, there are distinguishable periods of 4-6 years and 8-10 years in which the annual and seasonal vapor contents varied alternately between low and high concentrations. The annual vapor content and that of the four individual seasons all changed abruptly in about the mid-1980s （a〈0.05）. The west wind circulation, Tibetan Plateau circulation and the annual mean temperatures of the Tarim Basin are the main factors that influenced the surface vapor content over the study area, of which the Tibetan Plateau circulation may be the most important one.
基金sponsored by the Natural Science Foundation of China (Grant No. 41375101)the Special Fund for Meteorology-scientific Research in the Public Interest of China (Grant No. GYHY201006012)+2 种基金the Cooperation Program of National International Technological (Grant No. 2010DFA92720-14)Ministry of Water Resources Special Funds for Scientific Research on Public Causes (No.201301103)the Program for Innovative Research Team in University (Grant No. IRT1180)
文摘Based on the climate factors data and surface vapor pressure （SVP） data of 44 weather stations in Tianshan Mountains during the years 1961-2011, this paper establishes a water vapor content （WVC） estimation model according to the relationship between monthly WVC of radiosonde and corresponding SVP and analyzes the spatial and temporal variability of WVC and their causes. The results show that the WVC is linearly and negatively related to the elevation and longitude （Vertical zonality and Longitude zonality）, while it was not linearly related to the latitude. The westerly wind, geographical situation and sea level elevation composed complex surface conditions to influence the spatial distribution of WVC in the Tianshan Mountains. The Mann-Kendall （M-K） statistical test shows a significant increasing trend in the mean annual WVC in Tianshan Mountains during 1961- 2011（P 〈 0.001）, with a rate of 0.23 mm/decade, and indicates an abrupt turning point in 1985 （P.〈0.001）. Correlation analysis shows that the WVC are significantly correlated to the temperature, especially during the winter, but the summer WVC are significantly correlated to the precipitation. In addition, the North Atlantic Oscillation Index （NAOI） and the Arctic Oscillation Index （AOI） are significantly correlated to the winter WVC in the Tianshan Mountains. As a new Microwave radiometric profilers （MWRPs） instrument, the MP- 3000A provides continuous, real-time and high temporal resolution atmospheric profiles up to 10 km. In order to monitor water vapor and atmosphere profiles in Tianshan Mountains, an MP-3000A was established in Urumqi （43.8°N, 87.58°N） in May 2008. The results indicated that the MP-3oooA was applicable to this area, and the evolutionary process of water vapor and the WVC peak values of MP- 3000A were a strong signal for rainstorm and flood forecasts for Urumqi and the Tianshan Mountains.
基金Under the auspices of National Key Research and Development Program(No.2016YFC0500203)National Natural Science Foundation of China(No.41571427)
文摘Water vapor in the earth′s upper atmosphere plays a crucial role in the radiative balance, hydrological process, and climate change. Based on the latest moderate-resolution imaging spectroradiometer(MODIS) data, this study probes the spatio-temporal variations of global water vapor content in the past decade. It is found that overall the global water vapor content declined from 2003 to 2012(slope b = –0.0149, R = 0.893, P = 0.0005). The decreasing trend over the ocean surface(b = –0.0170, R = 0.908, P = 0.0003) is more explicit than that over terrestrial surface(b = –0.0100, R = 0.782, P = 0.0070), more significant over the Northern Hemisphere(b = –0.0175, R = 0.923, P = 0.0001) than that over the Southern Hemisphere(b = –0.0123, R = 0.826, P = 0.0030). In addition, the analytical results indicate that water vapor content are decreasing obviously between latitude of 36°N and 36°S(b = 0.0224, R = 0.892, P = 0.0005), especially between latitude of 0°N and 36°N(b = 0.0263, R = 0.931, P = 0.0001), while the water vapor concentrations are increasing slightly in the Arctic regions(b = 0.0028, R = 0.612, P = 0.0590). The decreasing and spatial variation of water vapor content regulates the effects of carbon dioxide which is the main reason of the trend in global surface temperatures becoming nearly flat since the late 1990 s. The spatio-temporal variations of water vapor content also affect the growth and spatial distribution of global vegetation which also regulates the global surface temperature change, and the climate change is mainly caused by the earth's orbit position in the solar and galaxy system. A big data model based on gravitational-magmatic change with the solar or the galactic system is proposed to be built for analyzing how the earth's orbit position in the solar and galaxy system affects spatio-temporal variations of global water vapor content, vegetation and temperature at large spatio-temporal scale. This comprehensive examination of water vapor changes promises a holistic understanding of the global climate change and potential underlying mechanisms.
文摘Spatial and temporal resolution of water vapor content is useful in improving the accuracy of short_term weather prediction.Dense and continuously tracking regional GPS arrays will play an important role in remote sensing atmospheric water vapor content.In this study,a piecewise linear solution method was proposed to estimate the precipitable water vapor (PWV) content from ground_based GPS observations in Hong Kong.To evaluate the solution accuracy of the water vapor content sensed by GPS,the upper air sounding data (radiosonde) that are collected locally was used to calculate the precipitable water vapor during the same period.One_month results of PWV from both ground_based GPS sensing technique and radiosonde method are in agreement within 1～2 mm.This encouraging result will motivate the GPS meteorology application based on the establishment of a dense GPS array in Hong Kong.
文摘Water vapor content in the atmosphere is very significant for atmospheric correction of optical remote sensing data. Nowadays, the common atmospheric correction models use a single value of the average water vapor content of the study area to perform atmospheric correction. As the distribution of water vapor content varies greatly with time and space, it is obviously inaccurate to represent the total water vapor conditions of the whole area by just reading the average water vapor content. In this study, we altered the 6S sources so that it could read the water vapor content image which was retrieved from MODIS 1 km data. Atmospheric correction was implemented for the band 1 of MODIS 500 m data pixel-by-pixel using the improved 6S model. In comparison with the traditional 6S model, this improved 6S model is more reasonable in atmospheric correction, for it considers the spatial distribution of the water vapor content retrieved from MODIS data in the near infrared to define the atmospheric conditions for simulating the atmospheric radiative transfer. The results corrected by the improved 6S model showed more reasonable in pixel spatial distribution and closer histogram with the original image than those by traditional 6S model.
文摘The interannual and intermonthly climatic features of the water vapor content(hereafter WVC)and its mean transfer in the atmosphere over Northwest China(hereafter NWC)are calculated and analyzed by using the NCEP/NCAR global reanalysis grid data(2.5°×2.5°Lat/Lon) for 40 years(1958—1997).The results show that the WVC in the total air column over NWC in four seasons of the year is mainly concentrated on eastern and western NWC respectively.On the average,the WVC over eastern NWC decreases obviously during recent forty years except for winter.while it decreases over western NWC in the whole year.But the WVC over NWC has been increasing since late 1980s in summer.The water vapor comes from the southwestern warm and wet air current along the Yarlung Zangbo River Valley and the Bay of Bengal.and from mid- western Tibetan Plateau and also from the Qinling Mountains at southern Shaanxi Province.The yearly water vapor divergence appears over the middle of NWC to northern Xinjiang and southeastern Shaanxi Province.The yearly water vapor convergence appears over the Tarim Basin and the Tibetan Plateau as well as western Sichuan and southern Gansu.
文摘In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Karsten's model at Kolkata, a tropical location in the Indian region. Cloud liquid water contents (LWC) are obtained from these profiles which show a prominent seasonal variation. The monsoon months exhibit much higher values of LWC than in other months. However Salonen's model yields higher LWC values than that obtained with Karsten's model. The variation of daily total rainfall with LWC shows a positive relationship indicating the role of LWC in controlling the rainfall. Also the variation pattern of LWC with integrated water vapor (IWV) content of the atmosphere indicates that a threshold value of water vapor is required for cloud to form and once cloud is formed LWC increases with IWV.
