The variation of air temperature measurement errors using two different radiation shields （DTR502B Vaisala,Finland,and HYTFZ01,Huayun Tongda Satcom,China） was studied.Datasets were collected in the field at the Daxi...The variation of air temperature measurement errors using two different radiation shields （DTR502B Vaisala,Finland,and HYTFZ01,Huayun Tongda Satcom,China） was studied.Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012.Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers （FRP） Stevenson screen.In most cases,the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield.The measured errors changed sharply at sunrise and sunset,and reached maxima at noon.Their diurnal variation characteristics were,naturally,related to changes in solar radiation.The relationships between the record errors,global radiation,and wind speed were nonlinear.An improved correction method was proposed based on the approach described by Nakamura and Mahrt （2005） （NM05）,in which the impact of the solar zenith angle （SZA） on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively.Measurement errors were reduced significantly after correction by either method for both shields.The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3％ and 40.4％ higher than those using the NM05 method,respectively.展开更多
利用河南东部商丘2023年5月3日一次积层混合云过程的飞机探测数据,研究分析了此次积层混合云的水平和垂直云微物理分布特征,并基于该特征讨论了人工增雨作业条件。结果表明,此次积层混合云过程由比较弱的倾斜西风槽过境形成,大气层结比...利用河南东部商丘2023年5月3日一次积层混合云过程的飞机探测数据,研究分析了此次积层混合云的水平和垂直云微物理分布特征,并基于该特征讨论了人工增雨作业条件。结果表明,此次积层混合云过程由比较弱的倾斜西风槽过境形成,大气层结比较稳定。降雨分布范围大且不均匀,雷达回波具有典型大范围层状云回波镶嵌对流泡回波的分布特征。并且飞机主要观测时段,研究区域降雨也比较强,对于揭示积层混合云结构特征和降水形成机制具有比较好的代表性。飞机观测显示,在层状云、对流泡边缘区域,过冷水含量很低,冰粒子以原始柱状冰晶为主。但在对流泡上部的冷云区,存在大量粒径在25μm以下的过冷云滴粒子,最大浓度达到10^(5)~10^(6) L^(-1)量级。过冷水含量最大值达到0.7 g m^(-3)以上。冰粒子主要以凇附状聚合体为主,浓度量级为10^(0)~10^(2) L^(-1)。由于低冰粒子浓度区域的过冷水含量比较高,适合冷云人工增雨作业。但由于高过冷水含量区的温度偏高,碘化银催化剂核化率低,更适合制冷剂(液氮、干冰)催化作业。展开更多
The Nested Air Quality Prediction Model System(NAQPMS)was used to investigate the temporal and spatial variations of PM2.5over tropospheric central eastern China in January 2013.The impact of regional transport and it...The Nested Air Quality Prediction Model System(NAQPMS)was used to investigate the temporal and spatial variations of PM2.5over tropospheric central eastern China in January 2013.The impact of regional transport and its implications on pollution prevention and control were also examined.Comparison between simulated and observed PM2.5showed NAQPMS was able to reproduce the evolution of PM2.5during heavy haze episodes.The results indicated that regional transport of PM2.5played an important role in regional haze episodes in the city cluster including Hebei,Beijing and Tianjin(HBT).The cross-city clusters transport outside HBT and transport among cities inside HBT contributed 20%–35%and 26%–35%of PM2.5as compared with local emission,in HBT respectively.To meet the Air Quality Standards for Grade II,90%,90%and65%of emissions would have to be cut down in Hebei,Tianjin and Beijing,if non-control strategy was taken in the surrounding city clusters of HBT.This implicated that control of emissions in one city cluster is not sufficient to reduce regional haze events,and joint efforts among city clusters are essential.Besides regional transports,two-way feedback between boundary-layer evolution and PM2.5also significantly contributed to the formation of heavy hazes,which contributed 30%of monthly average PM2.5concentration in HBT.展开更多
基金financially supported by the Meteorological Key Technology Integration and Application Project funded by the China Meteorological Administration (Grant No.CAMGJ2012M01)the Special Fund of Beijing Meteorological Bureau (Grant No.2011BMBKYZX04)the Nation Natural Science Foundation of China (Grant No.41275114)
文摘The variation of air temperature measurement errors using two different radiation shields （DTR502B Vaisala,Finland,and HYTFZ01,Huayun Tongda Satcom,China） was studied.Datasets were collected in the field at the Daxing weather station in Beijing from June 2011 to May 2012.Most air temperature values obtained with these two commonly used radiation shields were lower than the reference records obtained with the new Fiber Reinforced Polymers （FRP） Stevenson screen.In most cases,the air temperature errors when using the two devices were smaller on overcast and rainy days than on sunny days; and smaller when using the imported rather than the Chinese shield.The measured errors changed sharply at sunrise and sunset,and reached maxima at noon.Their diurnal variation characteristics were,naturally,related to changes in solar radiation.The relationships between the record errors,global radiation,and wind speed were nonlinear.An improved correction method was proposed based on the approach described by Nakamura and Mahrt （2005） （NM05）,in which the impact of the solar zenith angle （SZA） on the temperature error is considered and extreme errors due to changes in SZA can be corrected effectively.Measurement errors were reduced significantly after correction by either method for both shields.The error reduction rate using the improved correction method for the Chinese and imported shields were 3.3％ and 40.4％ higher than those using the NM05 method,respectively.
文摘利用河南东部商丘2023年5月3日一次积层混合云过程的飞机探测数据,研究分析了此次积层混合云的水平和垂直云微物理分布特征,并基于该特征讨论了人工增雨作业条件。结果表明,此次积层混合云过程由比较弱的倾斜西风槽过境形成,大气层结比较稳定。降雨分布范围大且不均匀,雷达回波具有典型大范围层状云回波镶嵌对流泡回波的分布特征。并且飞机主要观测时段,研究区域降雨也比较强,对于揭示积层混合云结构特征和降水形成机制具有比较好的代表性。飞机观测显示,在层状云、对流泡边缘区域,过冷水含量很低,冰粒子以原始柱状冰晶为主。但在对流泡上部的冷云区,存在大量粒径在25μm以下的过冷云滴粒子,最大浓度达到10^(5)~10^(6) L^(-1)量级。过冷水含量最大值达到0.7 g m^(-3)以上。冰粒子主要以凇附状聚合体为主,浓度量级为10^(0)~10^(2) L^(-1)。由于低冰粒子浓度区域的过冷水含量比较高,适合冷云人工增雨作业。但由于高过冷水含量区的温度偏高,碘化银催化剂核化率低,更适合制冷剂(液氮、干冰)催化作业。
基金supported by the CAS Strategic Priority Research Program(Grant Nos.XDB05030200 and XDB05030101)the National Natural Science Foundation of China(Grant No.41278138)
文摘The Nested Air Quality Prediction Model System(NAQPMS)was used to investigate the temporal and spatial variations of PM2.5over tropospheric central eastern China in January 2013.The impact of regional transport and its implications on pollution prevention and control were also examined.Comparison between simulated and observed PM2.5showed NAQPMS was able to reproduce the evolution of PM2.5during heavy haze episodes.The results indicated that regional transport of PM2.5played an important role in regional haze episodes in the city cluster including Hebei,Beijing and Tianjin(HBT).The cross-city clusters transport outside HBT and transport among cities inside HBT contributed 20%–35%and 26%–35%of PM2.5as compared with local emission,in HBT respectively.To meet the Air Quality Standards for Grade II,90%,90%and65%of emissions would have to be cut down in Hebei,Tianjin and Beijing,if non-control strategy was taken in the surrounding city clusters of HBT.This implicated that control of emissions in one city cluster is not sufficient to reduce regional haze events,and joint efforts among city clusters are essential.Besides regional transports,two-way feedback between boundary-layer evolution and PM2.5also significantly contributed to the formation of heavy hazes,which contributed 30%of monthly average PM2.5concentration in HBT.
