Precipitable Water Vapor(PWV)constitutes a pivotal parameter within the domains of atmospheric science,and remote sensing due to its profound influence on Earth’s climate dynamics and weather patterns.It exerts a sig...Precipitable Water Vapor(PWV)constitutes a pivotal parameter within the domains of atmospheric science,and remote sensing due to its profound influence on Earth’s climate dynamics and weather patterns.It exerts a significant impact on atmospheric stability absorption and emission of radiation,thus engendering alterations in the Earth’s radiative equilibrium.As such,precise quantification of PWV holds the potential to enhance weather prognostication and fortify preparedness against severe meteorological phenomena.This study aimed to elucidate the spatial and temporal changes in seasonal and annual PWV across the Indus River Basin and its sub-basins using ERA5 reanalysis datasets.The present study used ERA5 PWV(entire atmospheric column),air temperature at 2 m(t2m)and 500 hPa(T_500hPa),evapotranspiration,and total cloud cover data from 1960 to 2021.Theil Sen slope estimator and Mann-Kendall test were used for trend analysis.Correlation and multiple regression methods were used to understand the association of PWV with other factors.The findings have unveiled the highest increase in mean PWV during the monsoon(0.40 mm/decade),followed by premonsoon(0.37 mm/decade),post-monsoon(0.27 mm/decade),and winter(0.19 mm/decade)throughout the study period.Additionally,the mean PWV exhibited the most pronounced positive trend in the sub-basin Lower Indus(LI),followed by Panjnad(P),Kabul(K),and Upper Indus(UI)across all seasons,except winter.Annual PWV has also risen in the Indus basin and its sub-basins over the last six decades.PWV exhibits a consistent upward trend up to an elevation of 3500 m within the basin which is most pronounced during the monsoon season,followed by the pre-monsoon.The escalating PWV within the basin is reasonably ascribed to increasing air temperatures,augmented evapotranspiration,and heightened cloud cover.These findings hold potential utility for pertinent authorities engaged in water resource management and planning.展开更多
In recent studies of the Martian atmosphere,strong diurnal variation in the dust was discovered in the southern hemisphere during major dust storms,which provides strong evidence that the commonly recognized meridiona...In recent studies of the Martian atmosphere,strong diurnal variation in the dust was discovered in the southern hemisphere during major dust storms,which provides strong evidence that the commonly recognized meridional transport process is driven by thermal tides.This process,when coupled with deep convection,could be an important part of the short-term atmospheric dynamics of water escape.However,the potential of this process to alter the horizontal distribution of moist air has not been systematically investigated.In this work,we conducted pre-research on the horizontal transport of water vapor associated with the migrating diurnal tide(DW1)at 50 Pa in the upper troposphere during major dust storms based on the Mars Climate Database(MCD)5.3,a state-of-the-art database for Martian atmospheric research that has been validated as simulating the relevant short-period atmospheric dynamics well.We found westward-propagating diurnal patterns in the global water vapor front during nearly all the major dust storms from Martian years(MYs)24 to 32.Statistical and correlation analyses showed that the diurnal transport of water vapor during global and A-season regional dust storms is dominated by the DW1.The effect of the tidal transport of water vapor varies with the types of dust storms in different seasons.During regional dust storms,the tidal transport induces only limited diurnal motion of the water vapor.However,the horizontal tidal wind tends to increase the abundance of daytime water vapor at mid-to low latitudes during the MY 28 southern summer global dust storm while decreasing it during the MY 25 southern spring global dust storm.The tidal transport process during these two global dust storms can induce opposite effects on water escape.展开更多
The precision of atmospheric dry delay model is closely correlated with the accuracy of GPS water vapor in the process of GPS (Global Position System) remote sensing. Radiosonde data (from 1996 to 2001) at Qingyuan ar...The precision of atmospheric dry delay model is closely correlated with the accuracy of GPS water vapor in the process of GPS (Global Position System) remote sensing. Radiosonde data (from 1996 to 2001) at Qingyuan are used to calculate the exact values of the atmospheric dry delay. Base on these calculations and the surface meteorological parameters, the local year and month correction models of dry delay at the zenith angle of 0° are established by statistical methods. The analysis result shows that the local model works better and is slight more sensitive to altitude angle than universal models and that it is not necessary to build models for each month due to the slight difference between year model and month model. Furthermore, when the altitude angle is less than 75°, the difference between curve path and straight path increases rapidly with altitude angle’s decrease.展开更多
Diurnal temperature range(DTR) is an important measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correla...Diurnal temperature range(DTR) is an important measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water(PW) over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970–2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more(r2 ≥0.40) of the DTR changes, with a d(PW)/d(DTR) slope of-2% to-10% K-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from-0.42 to-0.75, with a d(PW)/d(DTR) slope of-6% to-11% K-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.展开更多
Nanosecond pulsed discharges at atmospheric pressure in a pin-to-pin electrode configuration are well reproducible in time and space, which is beneficial to the fundamentals and applications of low-temperature plasmas...Nanosecond pulsed discharges at atmospheric pressure in a pin-to-pin electrode configuration are well reproducible in time and space, which is beneficial to the fundamentals and applications of low-temperature plasmas. In this experiment, the discharges in helium(He) and He with 2.3%water vapor(H_(2)O) are driven by a series of 10 ns overvoltage pulses(~13 k V). Special attention is paid to the spectral characteristics obtained in the center of discharges by time-resolved optical emission spectroscopy. It is found that in helium, the emission of atomic and molecular helium during the afterglow is more intense than that in the active discharge, while in the He^(+)2.3%H_(2)O mixture, helium emission is only observed during the discharge pulse and the molecular helium emission disappears. In addition, the emissions of OH(A-X) and Hα present similar behavior that increases sharply during the falling edge of the voltage pulse as the electrons cool down rapidly. The gas temperature is set to remain low at 540 K by fitting the OH(A-X) band. A comparative study on the emission of radiative species(He, He_(2), OH and H)is performed between these two discharge cases to derive their main production mechanisms. In both cases, the dominant primary ion is He^(+) at the onset of discharges, but their He^(+) charge transfer processes are quite different. Based on these experimental data and a qualitative discussion on the discharge kinetics, with regard to the present discharge conditions, it is shown that the electron-assisted three-body recombination processes appear to be the significant sources of radiative OH and H species in high-density plasmas.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
Water is a basic need.However there are many near coastal regions which have very limited access to fresh water.The water in area close to coastal is mainly affected by ocean,indirectly by weather/climate conditions a...Water is a basic need.However there are many near coastal regions which have very limited access to fresh water.The water in area close to coastal is mainly affected by ocean,indirectly by weather/climate conditions and directly from seawater intrusion.While abundant fresh water is actually available in the atmosphere in the form of moisture.Recent technology,such as Atmospheric Water Generator(AWG),is a possible solution to gain water from our atmosphere.However,comprehensive study is needed to understand the potential water harvesting in our atmosphere.Here,we examine the water availability in the atmosphere based on several parameters like temperature and humidity.The data are collected from observation using WS1040 Automatic Weather Station in a year of 2020 with a half-hour interval.Then,we calculate the availability of water content during each season,especially in dry conditions.We also simulate the water harvesting to fulfil daily basic need of fresh water.The atmospheric parameters have shown a monsoonal pattern.Water content decrease in atmosphere during the dry season but the water deficit occurs after the dry season.Although water harvesting able to supply daily freshwater need,it is not recommended to be a single source as it requires massive water storage and high-efficient AWG.展开更多
Remote sensing of atmospheric water vapor using global positioning system(GPS) data has become an effective tool in meteorology,weather forecasting and climate research. This paper presents the estimation of precipi...Remote sensing of atmospheric water vapor using global positioning system(GPS) data has become an effective tool in meteorology,weather forecasting and climate research. This paper presents the estimation of precipitable water(PW)from GPS observations and meteorological data in Algeria,over three stations located at Algiers,Bechar and Tamanrasset.The objective of this study is to analyze the sensitivity of the GPS PW estimates for the three sites to the weighted mean temperature(T;),obtained separately from two types of T;–T;regression [one general,and one developed specifically for Algeria(T;stands for surface temperature)],and calculated directly from ERA-Interim data. The results show that the differences in T;are of the order of 18 K,producing differences of 2.01 mm in the final evaluation of PW. A good agreement is found between GPS-PW and PW calculated from radiosondes,with a small mean difference with Vaisala radiosondes.A comparison between GPS and ERA-Interim shows a large difference(4 mm) in the highlands region. This difference is possibly due to the topography. These first results are encouraging,in particular for meteorological applications in this region,with good hope to extend our dataset analysis to a more complete,nationwide coverage over Algeria.展开更多
The estimation of Precipitable Water Vapor (PWV) derived from Global Positioning System (GPS) data at the IGS site WUHN is assessed by comparing with PWV obtained from radiosonde data (No.57494) in Wuhan. The ap...The estimation of Precipitable Water Vapor (PWV) derived from Global Positioning System (GPS) data at the IGS site WUHN is assessed by comparing with PWV obtained from radiosonde data (No.57494) in Wuhan. The applicability of Saastamoinen (SAAS), Hopfield and Black models used for estimating Zenith Hydrostatic Delay (ZHD) and Zenith Wet Delay (ZWD) and different models is verified in the estimation of GPS-derived PWV for the applied area. The experimental results demonstrated that : 1 ) the precision of PWV estimated from Black model used for calculating ZHD ( ZHDs ) is lower than that of SAAS ( ZHDsAAs ) model and Hopfield model (ZHDn) with the RMS of 4. 16 ram; 2) the RMS of PWV estimated from SAAS model used for calculating ZWD (SAAS) is 3.78 ram; 3 ) the well-known Bevis model gives similar accuracy compared with the site-specific models for Tm in terms of surface temperature ( Ts ) and surface pressure (Ps), which can reach the accuracy inside 1 mm in the GPS-derived PWV estimates.展开更多
In the visible spectrum, the atmospheric attenuations to sunlight mainly include aerosol scattering, atmospheric molecule Rayleigh scattering and ozone absorption, while in the near-infrared spectrum (from 650 nm to 1...In the visible spectrum, the atmospheric attenuations to sunlight mainly include aerosol scattering, atmospheric molecule Rayleigh scattering and ozone absorption, while in the near-infrared spectrum (from 650 nm to 1 000 nm), we must take water-vapor absorption into account. Based on the atmospheric correction theory, using spectrum irradiance data measured by Instantaneous Ground spectrometer, ozone content measured by Microtops Ⅱozone monitor, water-vapor content and aerosol optical thickness measured by sun photometer, we give a new way to study water-vapor absorption to sunlight, and the result shows that the main peak values of water-vapor absorption coefficients are 0.025 cm-1, 0.073 cm-1, 0.124 cm-1, 0.090 cm-1, 0.141 cm-1 and 0.417 cm-1, which respectively lie at 692 nm, 725 nm, 761 nm, 818 nm, 912 nm and 937 nm.展开更多
为有效开发六盘山地区空中云水资源,提高人工增雨的科学性,需掌握该区域大气水汽的时空分布特征及其原因。利用1989—2018年六盘山地区国家基本站降水观测资料和同期欧洲中期天气预报中心(European Centre for Medium-Range Weather For...为有效开发六盘山地区空中云水资源,提高人工增雨的科学性,需掌握该区域大气水汽的时空分布特征及其原因。利用1989—2018年六盘山地区国家基本站降水观测资料和同期欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料(ERA5),分析该区域大气可降水量、比湿、相对湿度、水汽通量等大气水汽要素的时空变化,并从水汽输送、地形作用、浮力频率的影响等方面分析六盘山不同地区水汽条件及降水差异的原因。结果表明:一年中绝大多数时间六盘山山顶及东坡大气水汽条件均优于西坡,大值区主要集中在六盘山系主峰附近,并具有明显的季节变化特征。六盘山东坡,受地形抬升作用引起500 hPa辐散、700 hPa辐合的动力场,在夏季最明显,冬季最弱;浮力频率冬季最高,夏季最低;东坡更高的浮力频率及更陡峭的地形,使重力波效应更为明显,具备更有利的垂直上升扩散条件及更大的降水潜力。展开更多
基金the Banaras Hindu University,Varanasi,Uttar Pradesh(India),for providing a seed grant(Letter No.R/Dev/D/IoE/Equipment/Seed Grant-II/2022-23/52078)under the Institute of Eminence(IoE)Jyotsna Singh(Ref.No.210510120701),Subhash Singh(Ref.No.220510022095),and Purushottam Tiwari(Ref.No.210510406257)are grateful to the University Grants Commission(UGC)of the Ministry of Education,Government of India(New Delhi)for providing financial support to the present study+2 种基金the Copernicus Climate Change Service(C3S)team at the European Centre for Medium-Range Weather Forecasts(ECMWF)for providing ERA5 reanalysis data in the public domainreceived a seed grant from the Banaras Hindu University,Varanasi,Uttar Pradesh(India)(Letter No.R/Dev/D/IoE/Equipment/Seed Grant-II/2022-23/52078)under the Institute of Eminence(IoE)Jyotsna Singh(Ref.No.210510120701),Subhash Singh(Ref.No.220510022095),and Purushottam Tiwari(Ref.No.210510406257)received a fellowship from the University Grants Commission(UGC)of the Ministry of Education,Government of India(New Delhi)。
文摘Precipitable Water Vapor(PWV)constitutes a pivotal parameter within the domains of atmospheric science,and remote sensing due to its profound influence on Earth’s climate dynamics and weather patterns.It exerts a significant impact on atmospheric stability absorption and emission of radiation,thus engendering alterations in the Earth’s radiative equilibrium.As such,precise quantification of PWV holds the potential to enhance weather prognostication and fortify preparedness against severe meteorological phenomena.This study aimed to elucidate the spatial and temporal changes in seasonal and annual PWV across the Indus River Basin and its sub-basins using ERA5 reanalysis datasets.The present study used ERA5 PWV(entire atmospheric column),air temperature at 2 m(t2m)and 500 hPa(T_500hPa),evapotranspiration,and total cloud cover data from 1960 to 2021.Theil Sen slope estimator and Mann-Kendall test were used for trend analysis.Correlation and multiple regression methods were used to understand the association of PWV with other factors.The findings have unveiled the highest increase in mean PWV during the monsoon(0.40 mm/decade),followed by premonsoon(0.37 mm/decade),post-monsoon(0.27 mm/decade),and winter(0.19 mm/decade)throughout the study period.Additionally,the mean PWV exhibited the most pronounced positive trend in the sub-basin Lower Indus(LI),followed by Panjnad(P),Kabul(K),and Upper Indus(UI)across all seasons,except winter.Annual PWV has also risen in the Indus basin and its sub-basins over the last six decades.PWV exhibits a consistent upward trend up to an elevation of 3500 m within the basin which is most pronounced during the monsoon season,followed by the pre-monsoon.The escalating PWV within the basin is reasonably ascribed to increasing air temperatures,augmented evapotranspiration,and heightened cloud cover.These findings hold potential utility for pertinent authorities engaged in water resource management and planning.
基金This work is supported by the B-type Strategic Priority Program of the Chinese Academy of Sciences(grant XDB41000000)the pre-research project on Civil Aerospace Technologies of the China National Space Administration(grant D020105).T.L.and J.C.acknowledge support from the National Natural Science Foundation of China through grants 41525015 and 41774186 to J.C.,and grants 41674149 and 41974175 to T.L.X.Z.acknowledges support from the National Science Foundation(grant AST1740921).J.L.acknowledges support from the Open Research Program of the Chinese Academy of Sciences Key Laboratory of Geospace Environment.Z.W.acknowledges support from the Guangdong Basic and Applied Basic Research Foundation(grant 2019A1515110815)the Chinese Academy of Sciences Key Laboratory of Lunar and Deep Space Exploration(grant LDSE201803).We would like to thank the MCD teams for making the MCD 5.3 data sets available online at http://www-mars.lmd.jussieu.fr/mars/access.html.
文摘In recent studies of the Martian atmosphere,strong diurnal variation in the dust was discovered in the southern hemisphere during major dust storms,which provides strong evidence that the commonly recognized meridional transport process is driven by thermal tides.This process,when coupled with deep convection,could be an important part of the short-term atmospheric dynamics of water escape.However,the potential of this process to alter the horizontal distribution of moist air has not been systematically investigated.In this work,we conducted pre-research on the horizontal transport of water vapor associated with the migrating diurnal tide(DW1)at 50 Pa in the upper troposphere during major dust storms based on the Mars Climate Database(MCD)5.3,a state-of-the-art database for Martian atmospheric research that has been validated as simulating the relevant short-period atmospheric dynamics well.We found westward-propagating diurnal patterns in the global water vapor front during nearly all the major dust storms from Martian years(MYs)24 to 32.Statistical and correlation analyses showed that the diurnal transport of water vapor during global and A-season regional dust storms is dominated by the DW1.The effect of the tidal transport of water vapor varies with the types of dust storms in different seasons.During regional dust storms,the tidal transport induces only limited diurnal motion of the water vapor.However,the horizontal tidal wind tends to increase the abundance of daytime water vapor at mid-to low latitudes during the MY 28 southern summer global dust storm while decreasing it during the MY 25 southern spring global dust storm.The tidal transport process during these two global dust storms can induce opposite effects on water escape.
基金Sino-Italian Cooperation Project "An Integrated System for the Planning, Monitoring and Real-time Forecasting of Floods Risks"
文摘The precision of atmospheric dry delay model is closely correlated with the accuracy of GPS water vapor in the process of GPS (Global Position System) remote sensing. Radiosonde data (from 1996 to 2001) at Qingyuan are used to calculate the exact values of the atmospheric dry delay. Base on these calculations and the surface meteorological parameters, the local year and month correction models of dry delay at the zenith angle of 0° are established by statistical methods. The analysis result shows that the local model works better and is slight more sensitive to altitude angle than universal models and that it is not necessary to build models for each month due to the slight difference between year model and month model. Furthermore, when the altitude angle is less than 75°, the difference between curve path and straight path increases rapidly with altitude angle’s decrease.
基金funded by the National Basic Research Program of China (Grant No. 2012CB956203)the Strategic Priority Research Program-Climate Change: Carbon Budget and Relevant Issues of the Chinese Academy of Sciences (Grant No. XDA05090101)the Climate Change Special Fund of the China Meteorological Administration: Atmospheric Water Vapor Changes in China and Its Causes (Grant No. CCSF201330)
文摘Diurnal temperature range(DTR) is an important measure in studies of climate change and variability. The changes of DTR in different regions are affected by many different factors. In this study, the degree of correlation between the DTR and atmospheric precipitable water(PW) over China is explored using newly homogenized surface weather and sounding observations. The results show that PW changes broadly reflect the geographic patterns of DTR long-term trends over most of China during the period 1970–2012, with significant anticorrelations of trend patterns between the DTR and PW, especially over those regions with higher magnitude DTR trends. PW can largely explain about 40% or more(r2 ≥0.40) of the DTR changes, with a d(PW)/d(DTR) slope of-2% to-10% K-1 over most of northwestern and southeastern China, despite certain seasonal dependencies. For China as whole, the significant anticorrelations between the DTR and PW anomalies range from-0.42 to-0.75, with a d(PW)/d(DTR) slope of-6% to-11% K-1. This implies that long-term DTR changes are likely to be associated with opposite PW changes, approximately following the Clausius-Clapeyron equation. Furthermore, the relationship is more significant in the warm season than in the cold season. Thus, it is possible that PW can be considered as one potential factor when exploring long-term DTR changes over China. It should be noted that the present study has a largely statistical focus and that the underlying physical processes should therefore be examined in future work.
基金the funding provided by National Natural Science Foundation of China (No.12065019)Natural Science Foundation of the Jiangsu Higher Education Institutions of China (No. 20KJB140025)+1 种基金the Open Fund of the Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province(No. JBGS032)the Scientific Research Project for the Introduction Talent of Yancheng Institute of Technology(Nos. XJR2020031 and XJR2021069)。
文摘Nanosecond pulsed discharges at atmospheric pressure in a pin-to-pin electrode configuration are well reproducible in time and space, which is beneficial to the fundamentals and applications of low-temperature plasmas. In this experiment, the discharges in helium(He) and He with 2.3%water vapor(H_(2)O) are driven by a series of 10 ns overvoltage pulses(~13 k V). Special attention is paid to the spectral characteristics obtained in the center of discharges by time-resolved optical emission spectroscopy. It is found that in helium, the emission of atomic and molecular helium during the afterglow is more intense than that in the active discharge, while in the He^(+)2.3%H_(2)O mixture, helium emission is only observed during the discharge pulse and the molecular helium emission disappears. In addition, the emissions of OH(A-X) and Hα present similar behavior that increases sharply during the falling edge of the voltage pulse as the electrons cool down rapidly. The gas temperature is set to remain low at 540 K by fitting the OH(A-X) band. A comparative study on the emission of radiative species(He, He_(2), OH and H)is performed between these two discharge cases to derive their main production mechanisms. In both cases, the dominant primary ion is He^(+) at the onset of discharges, but their He^(+) charge transfer processes are quite different. Based on these experimental data and a qualitative discussion on the discharge kinetics, with regard to the present discharge conditions, it is shown that the electron-assisted three-body recombination processes appear to be the significant sources of radiative OH and H species in high-density plasmas.
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Water is a basic need.However there are many near coastal regions which have very limited access to fresh water.The water in area close to coastal is mainly affected by ocean,indirectly by weather/climate conditions and directly from seawater intrusion.While abundant fresh water is actually available in the atmosphere in the form of moisture.Recent technology,such as Atmospheric Water Generator(AWG),is a possible solution to gain water from our atmosphere.However,comprehensive study is needed to understand the potential water harvesting in our atmosphere.Here,we examine the water availability in the atmosphere based on several parameters like temperature and humidity.The data are collected from observation using WS1040 Automatic Weather Station in a year of 2020 with a half-hour interval.Then,we calculate the availability of water content during each season,especially in dry conditions.We also simulate the water harvesting to fulfil daily basic need of fresh water.The atmospheric parameters have shown a monsoonal pattern.Water content decrease in atmosphere during the dry season but the water deficit occurs after the dry season.Although water harvesting able to supply daily freshwater need,it is not recommended to be a single source as it requires massive water storage and high-efficient AWG.
文摘Remote sensing of atmospheric water vapor using global positioning system(GPS) data has become an effective tool in meteorology,weather forecasting and climate research. This paper presents the estimation of precipitable water(PW)from GPS observations and meteorological data in Algeria,over three stations located at Algiers,Bechar and Tamanrasset.The objective of this study is to analyze the sensitivity of the GPS PW estimates for the three sites to the weighted mean temperature(T;),obtained separately from two types of T;–T;regression [one general,and one developed specifically for Algeria(T;stands for surface temperature)],and calculated directly from ERA-Interim data. The results show that the differences in T;are of the order of 18 K,producing differences of 2.01 mm in the final evaluation of PW. A good agreement is found between GPS-PW and PW calculated from radiosondes,with a small mean difference with Vaisala radiosondes.A comparison between GPS and ERA-Interim shows a large difference(4 mm) in the highlands region. This difference is possibly due to the topography. These first results are encouraging,in particular for meteorological applications in this region,with good hope to extend our dataset analysis to a more complete,nationwide coverage over Algeria.
基金supported by the National Natural Science Foundation of China(4106400141071294)+1 种基金Guangxi Key Laboratory of Spatial Information and Geomatics(GuiKeJi 1103108-06)the Natural Science Foundation of Guangxi(2012GXNSFAA053183)
文摘The estimation of Precipitable Water Vapor (PWV) derived from Global Positioning System (GPS) data at the IGS site WUHN is assessed by comparing with PWV obtained from radiosonde data (No.57494) in Wuhan. The applicability of Saastamoinen (SAAS), Hopfield and Black models used for estimating Zenith Hydrostatic Delay (ZHD) and Zenith Wet Delay (ZWD) and different models is verified in the estimation of GPS-derived PWV for the applied area. The experimental results demonstrated that : 1 ) the precision of PWV estimated from Black model used for calculating ZHD ( ZHDs ) is lower than that of SAAS ( ZHDsAAs ) model and Hopfield model (ZHDn) with the RMS of 4. 16 ram; 2) the RMS of PWV estimated from SAAS model used for calculating ZWD (SAAS) is 3.78 ram; 3 ) the well-known Bevis model gives similar accuracy compared with the site-specific models for Tm in terms of surface temperature ( Ts ) and surface pressure (Ps), which can reach the accuracy inside 1 mm in the GPS-derived PWV estimates.
基金Financial support was provided by The National High Technology Research and Development Program of China(863 Program):No 2001AA633030 and 2001AA633080.
文摘In the visible spectrum, the atmospheric attenuations to sunlight mainly include aerosol scattering, atmospheric molecule Rayleigh scattering and ozone absorption, while in the near-infrared spectrum (from 650 nm to 1 000 nm), we must take water-vapor absorption into account. Based on the atmospheric correction theory, using spectrum irradiance data measured by Instantaneous Ground spectrometer, ozone content measured by Microtops Ⅱozone monitor, water-vapor content and aerosol optical thickness measured by sun photometer, we give a new way to study water-vapor absorption to sunlight, and the result shows that the main peak values of water-vapor absorption coefficients are 0.025 cm-1, 0.073 cm-1, 0.124 cm-1, 0.090 cm-1, 0.141 cm-1 and 0.417 cm-1, which respectively lie at 692 nm, 725 nm, 761 nm, 818 nm, 912 nm and 937 nm.
文摘为有效开发六盘山地区空中云水资源,提高人工增雨的科学性,需掌握该区域大气水汽的时空分布特征及其原因。利用1989—2018年六盘山地区国家基本站降水观测资料和同期欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts,ECMWF)第五代大气再分析资料(ERA5),分析该区域大气可降水量、比湿、相对湿度、水汽通量等大气水汽要素的时空变化,并从水汽输送、地形作用、浮力频率的影响等方面分析六盘山不同地区水汽条件及降水差异的原因。结果表明:一年中绝大多数时间六盘山山顶及东坡大气水汽条件均优于西坡,大值区主要集中在六盘山系主峰附近,并具有明显的季节变化特征。六盘山东坡,受地形抬升作用引起500 hPa辐散、700 hPa辐合的动力场,在夏季最明显,冬季最弱;浮力频率冬季最高,夏季最低;东坡更高的浮力频率及更陡峭的地形,使重力波效应更为明显,具备更有利的垂直上升扩散条件及更大的降水潜力。