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
A preliminarily assessment of the applicability of the sea surface pressure and wind speed of ERA5 reanalysis data is carried out using the observation data at 10 m height observation data of 9 buoys in the Bohai Sea ...A preliminarily assessment of the applicability of the sea surface pressure and wind speed of ERA5 reanalysis data is carried out using the observation data at 10 m height observation data of 9 buoys in the Bohai Sea and the Northern Huanghai Sea.The results show that:the sea surface pressure and wind speed of ERA5 reanalysis data has high correlation coefficients with the observation data,the correlation between sea surface pressure and wind speed is different in different time scales.The correlation of monthly average is better than that of daily average and daily extreme value,and the correlation coefficient is the lowest in extreme weather.In generally,the deviation between statistical products of the ERA5 and the observed products is negative.It means that the high pressure is weaker than the observed data,and the low pressure is stronger than the observed data,and there is some systematic deviation between ERA5 reanalysis data and the observed data.The deviation varies with the different wind speed level,when the wind is high,the reanalysis wind speed is generally less than the measured.By analyzing the monthly average data,the reanalysis data reveal the seasonal variation of sea surface pressure in the study area,and the deviation from the observed data also show seasonal variation characteristics,the applicability in winter is better than in summer.The error of reanalysis data of sea surface pressure and wind speed is large under extreme weather conditions,especially the typhoon process,further evaluation and revision of the data are needed.展开更多
ERA5 data and station observation data are both of great importance in studying the regional meteorological and environmental characteristics.The accuracy of ERA5 reanalysis wind field data was evaluated using observa...ERA5 data and station observation data are both of great importance in studying the regional meteorological and environmental characteristics.The accuracy of ERA5 reanalysis wind field data was evaluated using observations at five offshore platforms in Jiangsu sea area in this study.Results revealed that ERA5 wind speed was generally in reasonable agreement with that observed at each station,and that the accuracy of ERA5 wind speed data was significant better than that of wind direction.The consistency of wind direction between ERA5 and each observation station was better in autumn and winter than that in spring and summer.With increasing wind speed,the mean absolute error and root mean squared error between the ERA5 and observed wind speed(direction)data increased(decreased)obviously.During periods of typhoon,ERA5 wind data were largely consistent with observational data in terms of increasing wind speed and changing wind direction;however,the ERA5 wind speeds were slightly low.The findings of this study could provide a basis for the application and further research of ERA5 wind data in Jiangsu offshore sea area.展开更多
Lakes are an important component of the earth climate system. They play an important role in the study of basin weather forecasting, air quality forecasting, and regional climate research. The accuracy of driving vari...Lakes are an important component of the earth climate system. They play an important role in the study of basin weather forecasting, air quality forecasting, and regional climate research. The accuracy of driving variables is the basic premise to ensure the rationality of lake mode simulation. Based on the in-situ observations at Bifenggang site of the Lake Taihu Eddy flux Network from 2012 to 2017, this paper investigated temporal variations in temperature, relative humidity, wind speed, radiation components at different time scales (hourly, seasonal and interannual). ERA5 reanalysis data were compared with in-situ observation to quantify the error and evaluate the performance of reanalysis data. The results show that: 1) On the hourly scale, the ERA5 reanalysis data described air temperature, and downward long-wave radiation more accurately. 2) On the seasonal variation scale, the ERA5 reanalysis data described air temperature, and downward long-wave radiation more accurately. However, the descriptions of wind speed, relative humidity and downward short-wave have large deviations. 3) On the interannual scale, the ERA5 reanalysis data show a good performance for temperature, followed by downward longwave radiation, downward shortwave radiation and relative humidity.展开更多
利用渤海海域5个代表性站点的海浪现场观测资料,从波高、周期和波向三个方面对欧洲中期天气预报中心第五代全球气候再分析数据集(European Centre for Medium-Range Weather Forecasts Reanalysis v5,ERA5)的海浪资料在渤海海域的适用...利用渤海海域5个代表性站点的海浪现场观测资料,从波高、周期和波向三个方面对欧洲中期天气预报中心第五代全球气候再分析数据集(European Centre for Medium-Range Weather Forecasts Reanalysis v5,ERA5)的海浪资料在渤海海域的适用性进行了评估。结果表明:ERA5海浪要素的时间变化趋势与实测资料基本吻合,但量值大小存在一定差异,不同站点不同要素之间的统计结果也有一定差异。ERA5海浪资料与实测资料之间,有效波高的相关性最高,约在0.9以上,谱峰周期次之,平均波向最差。离岸最近的站点有效波高和谱峰周期要素的相关性均为最低,2个要素的误差在离岸最近站点也为最大,在离岸较远的站点,海浪要素的整体表现均较好。就3个代表性要素资料使用而言,ERA5海浪要素需要进行一定的量值订正处理,特别是波向资料。整体上,ERA5的海浪产品在渤海海域具有一定的适用性,基于ERA5产品分析海浪的统计特征是可行的。展开更多
基于台站观测资料,评估了欧洲中期天气预报中心(ECMWF)最高时空分辨率的第五代大气再分析资料(ERA5)对1979~2018年间中国大陆区域10 m高度风速的气候特征及其变化趋势的再现能力,并同步对比分析了ERA5资料100 m高度风速的特征和长期趋...基于台站观测资料,评估了欧洲中期天气预报中心(ECMWF)最高时空分辨率的第五代大气再分析资料(ERA5)对1979~2018年间中国大陆区域10 m高度风速的气候特征及其变化趋势的再现能力,并同步对比分析了ERA5资料100 m高度风速的特征和长期趋势。结果表明,ERA5资料10 m和100 m风速在空间分布、年—季节—月尺度演变的气候特征方面与台站观测非常一致,10 m风速气候态空间相关系数达到0.66。观测和再分析资料均显示,中国近地层风速呈现出显著的区域性特征,风速大值区主要分布在内蒙古、东北地区西部、新疆北部以及青藏高原西部地区,上述区域的风速季节差异也相对明显,春季风速最大。台站观测、ERA5资料10 m和100 m全国平均风速在4月达到最大值,分别为2.6、3.0、4.5 m s^(-1),8月为最小值,分别为2.0、2.4、3.5 m s^(-1)。从月平均序列来看,ERA5资料的10 m风速较台站观测偏高0.3~0.5 m s^(-1),而100 m的风速较10 m风速整体偏高1.2~1.4 m s^(-1)。在风速变化方面,台站观测风速在中国陆地区域整体呈下降趋势–0.4 m s^(-1)(39 a)–1,春季下降趋势最显著[–0.5 m s^(-1)(39 a)–1],且1979~1992年冬季风速降幅最大[–0.7 m s^(-1)(14 a)–1],2013年以后风速逐渐增强。ERA5资料两个高度层的风速在整个中国区域均没有明显的长期变化趋势,4个季节风速变化趋势的空间分布与观测也存在差异,100m风速的长期变化趋势与10 m一致但变化幅度大于10 m风速。总之,ERA5资料对中国大陆区域气候平均风速具有较好的再现能力,但无法呈现台站观测风速的长期变化趋势。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.
文摘A preliminarily assessment of the applicability of the sea surface pressure and wind speed of ERA5 reanalysis data is carried out using the observation data at 10 m height observation data of 9 buoys in the Bohai Sea and the Northern Huanghai Sea.The results show that:the sea surface pressure and wind speed of ERA5 reanalysis data has high correlation coefficients with the observation data,the correlation between sea surface pressure and wind speed is different in different time scales.The correlation of monthly average is better than that of daily average and daily extreme value,and the correlation coefficient is the lowest in extreme weather.In generally,the deviation between statistical products of the ERA5 and the observed products is negative.It means that the high pressure is weaker than the observed data,and the low pressure is stronger than the observed data,and there is some systematic deviation between ERA5 reanalysis data and the observed data.The deviation varies with the different wind speed level,when the wind is high,the reanalysis wind speed is generally less than the measured.By analyzing the monthly average data,the reanalysis data reveal the seasonal variation of sea surface pressure in the study area,and the deviation from the observed data also show seasonal variation characteristics,the applicability in winter is better than in summer.The error of reanalysis data of sea surface pressure and wind speed is large under extreme weather conditions,especially the typhoon process,further evaluation and revision of the data are needed.
文摘ERA5 data and station observation data are both of great importance in studying the regional meteorological and environmental characteristics.The accuracy of ERA5 reanalysis wind field data was evaluated using observations at five offshore platforms in Jiangsu sea area in this study.Results revealed that ERA5 wind speed was generally in reasonable agreement with that observed at each station,and that the accuracy of ERA5 wind speed data was significant better than that of wind direction.The consistency of wind direction between ERA5 and each observation station was better in autumn and winter than that in spring and summer.With increasing wind speed,the mean absolute error and root mean squared error between the ERA5 and observed wind speed(direction)data increased(decreased)obviously.During periods of typhoon,ERA5 wind data were largely consistent with observational data in terms of increasing wind speed and changing wind direction;however,the ERA5 wind speeds were slightly low.The findings of this study could provide a basis for the application and further research of ERA5 wind data in Jiangsu offshore sea area.
文摘Lakes are an important component of the earth climate system. They play an important role in the study of basin weather forecasting, air quality forecasting, and regional climate research. The accuracy of driving variables is the basic premise to ensure the rationality of lake mode simulation. Based on the in-situ observations at Bifenggang site of the Lake Taihu Eddy flux Network from 2012 to 2017, this paper investigated temporal variations in temperature, relative humidity, wind speed, radiation components at different time scales (hourly, seasonal and interannual). ERA5 reanalysis data were compared with in-situ observation to quantify the error and evaluate the performance of reanalysis data. The results show that: 1) On the hourly scale, the ERA5 reanalysis data described air temperature, and downward long-wave radiation more accurately. 2) On the seasonal variation scale, the ERA5 reanalysis data described air temperature, and downward long-wave radiation more accurately. However, the descriptions of wind speed, relative humidity and downward short-wave have large deviations. 3) On the interannual scale, the ERA5 reanalysis data show a good performance for temperature, followed by downward longwave radiation, downward shortwave radiation and relative humidity.
文摘利用渤海海域5个代表性站点的海浪现场观测资料,从波高、周期和波向三个方面对欧洲中期天气预报中心第五代全球气候再分析数据集(European Centre for Medium-Range Weather Forecasts Reanalysis v5,ERA5)的海浪资料在渤海海域的适用性进行了评估。结果表明:ERA5海浪要素的时间变化趋势与实测资料基本吻合,但量值大小存在一定差异,不同站点不同要素之间的统计结果也有一定差异。ERA5海浪资料与实测资料之间,有效波高的相关性最高,约在0.9以上,谱峰周期次之,平均波向最差。离岸最近的站点有效波高和谱峰周期要素的相关性均为最低,2个要素的误差在离岸最近站点也为最大,在离岸较远的站点,海浪要素的整体表现均较好。就3个代表性要素资料使用而言,ERA5海浪要素需要进行一定的量值订正处理,特别是波向资料。整体上,ERA5的海浪产品在渤海海域具有一定的适用性,基于ERA5产品分析海浪的统计特征是可行的。
文摘基于台站观测资料,评估了欧洲中期天气预报中心(ECMWF)最高时空分辨率的第五代大气再分析资料(ERA5)对1979~2018年间中国大陆区域10 m高度风速的气候特征及其变化趋势的再现能力,并同步对比分析了ERA5资料100 m高度风速的特征和长期趋势。结果表明,ERA5资料10 m和100 m风速在空间分布、年—季节—月尺度演变的气候特征方面与台站观测非常一致,10 m风速气候态空间相关系数达到0.66。观测和再分析资料均显示,中国近地层风速呈现出显著的区域性特征,风速大值区主要分布在内蒙古、东北地区西部、新疆北部以及青藏高原西部地区,上述区域的风速季节差异也相对明显,春季风速最大。台站观测、ERA5资料10 m和100 m全国平均风速在4月达到最大值,分别为2.6、3.0、4.5 m s^(-1),8月为最小值,分别为2.0、2.4、3.5 m s^(-1)。从月平均序列来看,ERA5资料的10 m风速较台站观测偏高0.3~0.5 m s^(-1),而100 m的风速较10 m风速整体偏高1.2~1.4 m s^(-1)。在风速变化方面,台站观测风速在中国陆地区域整体呈下降趋势–0.4 m s^(-1)(39 a)–1,春季下降趋势最显著[–0.5 m s^(-1)(39 a)–1],且1979~1992年冬季风速降幅最大[–0.7 m s^(-1)(14 a)–1],2013年以后风速逐渐增强。ERA5资料两个高度层的风速在整个中国区域均没有明显的长期变化趋势,4个季节风速变化趋势的空间分布与观测也存在差异,100m风速的长期变化趋势与10 m一致但变化幅度大于10 m风速。总之,ERA5资料对中国大陆区域气候平均风速具有较好的再现能力,但无法呈现台站观测风速的长期变化趋势。
