青藏高原及周边UTLS水汽时空特征的多源资料对比
投稿时间: 2017-07-06  最后修改时间: 2018-03-01  点此下载全文
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作者单位E-mail
唐南军 南京信息工程大学资料同化研究与应用中心 tangnanjun@sina.com 
任荣彩 中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室 rrc@lasg.iap.ac.cn 
中文摘要:利用Aura卫星微波临边观测仪(Microwave Limb Sounder,MLS)数据,本文首先评估了ERAi、MERRA、JRA-55、CFSR和NCEP2等5套再分析资料中的水汽数据在青藏高原及周边上对流层—下平流层(upper troposphere and lower stratosphere,UTLS)层次的质量,然后选取其中质量较好的两套水汽数据,分析它们对青藏高原及周边UTLS水汽的时空分布和演变的表征能力。结果表明,与MLS数据相比,5套再分析资料中在UTLS处普遍偏湿和偏暖,ERAi、MERRA、JRA-55和CFSR中在上对流层215 hPa偏湿最大可达165%,而在下平流层区域,ERAi和MERRA与MLS的差异相对较小。总的来看,ERAi和MERRA表征的水汽与MLS更为接近。进一步的对比表明,ERAi和MERRA中青藏高原及周边水汽含量的时空分布与MLS较为接近,夏季能够表征青藏高原在纬向和经向上的水汽高值区,冬季能够表征对流层顶急流中心附近的水汽梯度带,而且MERRA的结果要好于ERAi。ERAi、MERRA和MLS中青藏高原地区的水汽季节演变都表现为冬季1—2月水汽含量低,夏季7—8月水汽含量高,水汽的季节变化在200 ~ 300 hPa最大。MLS资料显示,在青藏高原地区对流层顶附近,存在随时间向上向极的水汽传输信号。相较而言,ERAi对水汽在垂直方向上的传输信号表征更好,而MERRA对下平流层(100 hPa)水汽的向极传输信号则表征的更好。
中文关键词:青藏高原  再分析资料与MLS观测  上对流层-下平流层水汽  对比分析
 
Comparison of upper troposphere and lower stratosphere water vapor spatial and temporal distribution over Tibetan Plateau in Reanalysis data and MLS observa-tions
Abstract:Understanding the bias in reanalysis water vapor data was helpful in studying the stratosphere and troposphere water vapor transport, especially over Tibetan Plateau (TP), where was the important water vapor source in extratropical. In this paper, Aura MLS satellite observations over TB was used to evaluate upper troposphere and lower stratosphere (UTLS) water vapor from ERAi, MERRA, JRA-55, CFSR and NCEP2 reanalysis data during August 2004 to December 2013. It was showed that water vapor from ERAi and MERRA were better than other reanalysis data, and water vapor spatial and temporal distribution in ERAi and MERRA were further compared by MLS satellite observations. The contrast result showed that all reanalysis data we used were wetter and warmer in UTLS compared to MLS satellite observations. The ERAi, MERRA, JRA-55 and CFSR reanalysis data overestimated the upper tropo-spheric (215hPa) water vapor amount by up to 165% compared to MLS observations, while water vapor from ERAi and MERRA has small difference with MLS observations. Overall, water vapor data from ERAi and MERRA were closer to MLS observations compared to other reanalysis data. Further contrast results showed that water vapor horizontal and vertical structure in ERAi and MERRA were consistent with MLS observations over TB in winter and summer. In MLS observations, the water vapor maximum in latitude and longitude was over TP in summer, and there was strong meridional gradient near tropopause and jet center in winter, which were also found in ERAi and MERRA, but the spatial distribution was better in MERRA. The water vapor amount over TB had obvious seasonal change, which was highest in January and February and lowest in July and August, and the seasonal variability was largest during 200 ~ 300 hPa. The seasonal change in ERAi and MERRA resembled MLS observations, but the seasonal variability was slightly larger (smaller) in ERAi and MERRA in upper troposphere (lower stratosphere). According to daily water vapor time series, there was upward and poleward transport near tropopause in MLS observations over TB. The upward and poleward transport can also be found in ERAi and MERRA daily water vapor data time series, but compared to MLS result, the upward higher water vapor transport was better in ERAi, while the poleward higher water vapor transport was more obvious in MERRA in lower strat-osphere (100hPa). In a word, although the water vapor amount in ERAi and MERRA had large difference with MLS observation in upper troposphere, the spatial and temporal distribution were closer to MLS observation, so the ERAi and MERRA water vapor data was a good supplement to study the water vapor transport over TB.
keywords:Tibetan Plateau  reanalysis data and MLS observation  upper troposphere and lower stratosphere water vapor  comparative analysis
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