An assessment of upper troposphere and lower stratosphere water vapor in MERRA, MERRA2, and ECMWF reanalyses using Aura MLS observations
An assessment of upper troposphere and lower stratosphere water vapor in MERRA, MERRA2, and ECMWF reanalyses using Aura MLS observations
复制标题
DOI：
10.1002/2015jd023752
复制
发表时间：
2015-11
期刊：
影响因子：
--
通讯作者：
J. Jiang;H. Su;C. Zhai;Longtao Wu;K. Minschwaner;A. Molod;A. Tompkins
中科院分区：
文献类型：
--
作者：
J. Jiang;H. Su;C. Zhai;Longtao Wu;K. Minschwaner;A. Molod;A. Tompkins
使用微波测深仪(MLS)的全球水汽(H2O)测量来评估NASA现代研究与应用回顾分析(MERRA)及其最新发布的MERRA2和欧洲中期天气预报中心(ECMWF)中期再分析产生的上对流层(UT)和下平流层(LS)H2O产品。我们把重点放在了从UT到LS的H2O量和输送上，结果表明，与MLS观测相比，所有再分析都高估了全球年平均UT H2O高达约150%。在观测和再分析之间也发现了H2O输送方面的实质性差异。在垂直方向上，再分析中H2O通过热带对流层顶(16-20公里)的输送比MLS观测快86%。在热带最低层(21-25公里)，来自ECMWF的平均垂直输送比MLS估计快168%，而MERRA和MERRA2的垂直输送速度在MLS值的10%以内。在100百帕的水平上，观测和再分析都表明北半球(NH)比南半球(SH)向极地输送更快。与MLS观测相比，MERRA和MERRA2的H2O水平输送在NH中的速度要快106%，而在SH中的速度要慢42-45%。在两个半球，ECMWF的水平传输比MLS观测快16%。ECMWF的南北输送速度之比为1.4，与MLS观测一致，而MERRA和MERRA2的相应之比约为MERRA的3.5倍。
Global water vapor (H2O) measurements from Microwave Limb Sounder (MLS) are used to evaluate upper tropospheric (UT) and lower stratospheric (LS) H2O products produced by NASA Modern‐Era Retrospective Analysis for Research and Applications (MERRA), its newest release MERRA2, and European Centre for Medium‐Range Weather Forecasts (ECMWF) Interim Reanalyses. Focusing on the H2O amount and transport from UT to LS, we show that all reanalyses overestimate annual global mean UT H2O by up to ~150% compared to MLS observations. Substantial differences in H2O transport are also found between the observations and reanalyses. Vertically, H2O transport across the tropical tropopause (16–20 km) in the reanalyses is faster by up to ~86% compared to MLS observations. In the tropical LS (21–25 km), the mean vertical transport from ECMWF is 168% faster than the MLS estimate, while MERRA and MERRA2 have vertical transport velocities within 10% of MLS values. Horizontally at 100 hPa, both observation and reanalyses show faster poleward transport in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH). Compared to MLS observations, the H2O horizontal transport for both MERRA and MERRA2 is 106% faster in the NH but about 42–45% slower in the SH. ECMWF horizontal transport is 16% faster than MLS observations in both hemispheres. The ratio of northward to southward transport velocities for ECMWF is 1.4, which agrees with MLS observation, while the corresponding ratios for MERRA and MERRA2 are about 3.5 times larger.