A validation study of land surface temperature (LST) obtained from the Ka band (37 GHz) vertically polarized brightness temperature over northern China is presented.The remotely sensed LST derived jointly by the Vrije...A validation study of land surface temperature (LST) obtained from the Ka band (37 GHz) vertically polarized brightness temperature over northern China is presented.The remotely sensed LST derived jointly by the Vrije Universiteit Amsterdam and the NASA Goddard Space Flight Center (VUA-NASA) from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) were compared to the daily in-situ top soil temperature/infrared surface temperature observations from eleven/three Enhanced Coordinated Observation stations in arid and semi-arid regions of northern China.The VUA-NASA LST from the descending path exhibited a stronger correspondence to the in-situ infrared surface temperature than soil temperature observations,whereas correlations (R 2) of the latter ranged from 0.41 to 0.86.Meanwhile,the ascending overpass LST was generally warmer than the in-situ soil temperature observations at all stations,and the correlation (R 2) was between 0.07 and 0.72.Furthermore,the correlation of the descending path was generally greater than that of the ascending path at the same station.The descending path VUA-NASA LST was sensitive to precipitation and presented good agreement with ground temperature dynamics.The analyses demonstrated that the descending overpass LST was reliable to reflect reasonable patterns of temperature dynamics for land surface temperature in the region.展开更多
Based on the daily maximum surface air temperature records from an updated homogenized temperature dataset for 549 Chinese stations during 1960-2008,we reveal that there is an abrupt increase in the number of days wit...Based on the daily maximum surface air temperature records from an updated homogenized temperature dataset for 549 Chinese stations during 1960-2008,we reveal that there is an abrupt increase in the number of days with high temperature extremes （HTEs,an HTE day is defined when the maximum temperature exceeds the 95th percentile of the daily maximum temperature distributions） across China in the mid-1990s.Before this regime shift,the average number of HTE days is about 2.9 d yr 1 during the period from the 1970s to the early 1990s,while it rocketed to about 7.2 d yr 1 after the mid-1990s.We show that the significant HTE day increase occurs uniformly across the whole of China after the regime shift.The observational evidence raises the possibility that this change in HTE days is associated with global-scale warming as well as circulation adjustment.Possible causes for the abrupt change in the HTE days are discussed,and the circulation adjustment is suggested to play a crucial role in the increase in HTE days in this region.展开更多
A set of homogenized monthly mean surface air temperature （SAT） series at 32 stations in China back to the 19th century had previously been developed based on the RHtest method by Cao et al., but some inhomogeneitie...A set of homogenized monthly mean surface air temperature （SAT） series at 32 stations in China back to the 19th century had previously been developed based on the RHtest method by Cao et al., but some inhomogeneities remained in the dataset. The present study produces a further-adjusted and updated dataset based on the Multiple Analysis of Series for Homogenization （MASH） method. The MASH procedure detects 33 monthly temperature records as erroneous outliers and 152 meaningful break points in the monthly SAT series since 1924 at 28 stations. The inhomogeneous parts are then adjusted relative to the latest homogeneous part of the series. The new data show significant warming trends during 1924-2016 at all the stations, ranging from 0.48 to 3.57℃ （100 yr）^-1, with a regional mean trend of 1.65℃ （100 yr）^-1 ; whereas, the previous results ranged from a slight cooling at two stations to considerable warming, up to 4.5℃ （100 yr）^-1. It is suggested that the further-adjusted data are a better representation of the large-scale pattern of climate change in the region for the past century. The new data axe available online at http：//www.dx.doi.org/10.11922/sciencedb.516.展开更多
基金supported by the National Basic Research Program of China (Grant No.2009CB723904)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA05090201)
文摘A validation study of land surface temperature (LST) obtained from the Ka band (37 GHz) vertically polarized brightness temperature over northern China is presented.The remotely sensed LST derived jointly by the Vrije Universiteit Amsterdam and the NASA Goddard Space Flight Center (VUA-NASA) from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) were compared to the daily in-situ top soil temperature/infrared surface temperature observations from eleven/three Enhanced Coordinated Observation stations in arid and semi-arid regions of northern China.The VUA-NASA LST from the descending path exhibited a stronger correspondence to the in-situ infrared surface temperature than soil temperature observations,whereas correlations (R 2) of the latter ranged from 0.41 to 0.86.Meanwhile,the ascending overpass LST was generally warmer than the in-situ soil temperature observations at all stations,and the correlation (R 2) was between 0.07 and 0.72.Furthermore,the correlation of the descending path was generally greater than that of the ascending path at the same station.The descending path VUA-NASA LST was sensitive to precipitation and presented good agreement with ground temperature dynamics.The analyses demonstrated that the descending overpass LST was reliable to reflect reasonable patterns of temperature dynamics for land surface temperature in the region.
基金supported by National Key Technology R & D Program 2008BAK50B02National Basic Research Program of China under Grant No. 2009CB421405the National Natural Science Foundation of China under Grant Nos. 40730952 and 40805017
文摘Based on the daily maximum surface air temperature records from an updated homogenized temperature dataset for 549 Chinese stations during 1960-2008,we reveal that there is an abrupt increase in the number of days with high temperature extremes （HTEs,an HTE day is defined when the maximum temperature exceeds the 95th percentile of the daily maximum temperature distributions） across China in the mid-1990s.Before this regime shift,the average number of HTE days is about 2.9 d yr 1 during the period from the 1970s to the early 1990s,while it rocketed to about 7.2 d yr 1 after the mid-1990s.We show that the significant HTE day increase occurs uniformly across the whole of China after the regime shift.The observational evidence raises the possibility that this change in HTE days is associated with global-scale warming as well as circulation adjustment.Possible causes for the abrupt change in the HTE days are discussed,and the circulation adjustment is suggested to play a crucial role in the increase in HTE days in this region.
基金supported by the Chinese Academy of Sciences International Collaboration Program(Grant No.134111KYSB20160010)the National Natural Science Foundation of China(Grant Nos.41505071 and 41475078)the UK-China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP) China as part of the Newton Fund
文摘A set of homogenized monthly mean surface air temperature （SAT） series at 32 stations in China back to the 19th century had previously been developed based on the RHtest method by Cao et al., but some inhomogeneities remained in the dataset. The present study produces a further-adjusted and updated dataset based on the Multiple Analysis of Series for Homogenization （MASH） method. The MASH procedure detects 33 monthly temperature records as erroneous outliers and 152 meaningful break points in the monthly SAT series since 1924 at 28 stations. The inhomogeneous parts are then adjusted relative to the latest homogeneous part of the series. The new data show significant warming trends during 1924-2016 at all the stations, ranging from 0.48 to 3.57℃ （100 yr）^-1, with a regional mean trend of 1.65℃ （100 yr）^-1 ; whereas, the previous results ranged from a slight cooling at two stations to considerable warming, up to 4.5℃ （100 yr）^-1. It is suggested that the further-adjusted data are a better representation of the large-scale pattern of climate change in the region for the past century. The new data axe available online at http：//www.dx.doi.org/10.11922/sciencedb.516.
