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Assessment of Upper Tropospheric Water Vapor Monthly Variation in Reanalyses With Near‐Global Homogenized 6.5‐μm Radiances From Geostationary Satellites
Journal of Geophysical Research: Atmospheres ( IF 4.4 ) Pub Date : 2020-09-01 , DOI: 10.1029/2020jd032695
Yunheng Xue 1, 2, 3 , Jun Li 2 , Zhenglong Li 2 , Riyu Lu 1 , Mathew M. Gunshor 2 , Szuchia L. Moeller 2 , Di Di 4 , Timothy J. Schmit 5
Affiliation  

The monthly variation of upper tropospheric water vapor (UTWV) simulated by six reanalysis data sets is evaluated with homogenized water vapor radiance observations from international geostationary (GEO) weather satellites by using a profile‐to‐radiance approach over 45°N to 45°S regions for the period 2015–2017. Results show that reanalysis data sets have an overall good agreement with observations. However, a widespread wet bias is found in all reanalyses and is more dominant in large‐scale subsidence regions. JRA55 has the smallest wet bias while MERRA‐2 exhibits the most humid upper troposphere. The temporal variation of brightness temperatures in response to the warm phase of El Niño‐Southern Oscillation (ENSO) in 2015–2016 indicates that the UTWV field is regulated by both ascending and descending branches of the large‐scale circulation. All six reanalyses roughly capture the temporal variation of UTWV in the developing and decay year of this ENSO event. However, they tend to overestimate the eastward propagation of high UTWV in the developing year, especially MERRA‐2. The UTWV gradient over the tropical Pacific in the decay year is underestimated, with a dry bias over the convective western Pacific and a wet bias over the eastern Pacific in reanalysis data sets. These results may provide a useful tool for the climate modeling community for identifying and solving problems associated with UTWV simulation.

中文翻译:

用对地静止卫星近全球均质的6.5μm辐射重新分析中对流层上层水汽每月变化的评估

使用从45°N至45°S的剖面辐射比方法,利用来自国际对地静止(GEO)天气卫星的均质水蒸气辐射观测值,评估了由六个再分析数据集模拟的对流层高层水蒸气(UTWV)的每月变化2015-2017年期间的区域。结果表明,重新分析数据集与观察结果总体上吻合良好。但是,在所有重新分析中都发现了广泛的湿偏振,并且在大规模沉降区域中更为明显。JRA55的湿偏压最小,而MERRA-2的湿对流层最高。2015-2016年厄尔尼诺-南方涛动(ENSO)暖期响应时,亮度温度的时间变化表明,UTWV场受大尺度环流的上升和下降分支调节。所有六个重新分析都大致记录了该ENSO事件发展和衰减年中UTWV的时间变化。但是,它们往往高估了发展中年份高UTWV的向东传播,特别是MERRA-2。在再分析数据集中,低估了衰减年份热带太平洋上的UTWV梯度,对流西太平洋上有干偏差,东太平洋上有湿偏差。这些结果可能为气候建模界提供有用的工具,以识别和解决与UTWV模拟相关的问题。在再分析数据集中,低估了衰减年份热带太平洋上的UTWV梯度,对流西太平洋上有干偏差,东太平洋上有湿偏差。这些结果可能为气候建模界提供有用的工具,以识别和解决与UTWV模拟相关的问题。在再分析数据集中,低估了衰减年份热带太平洋上的UTWV梯度,对流西太平洋上有干偏差,东太平洋上有湿偏差。这些结果可能为气候建模界提供有用的工具,以识别和解决与UTWV模拟相关的问题。
更新日期:2020-09-20
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