The JRA-55 Reanalysis: Representation of Atmospheric Circulation and Climate Variability
The JRA-55 Reanalysis: Representation of Atmospheric Circulation and Climate Variability
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DOI：
10.2151/jmsj.2016-015
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发表时间：
2016-01-01
影响因子：
3.1
通讯作者：
Takahashi, Kiyotoshi
中科院分区：
文献类型：
--
作者：
Harada, Yayoi;Kamahori, Hirotaka;Takahashi, Kiyotoshi
本研究通过与其他再分析和观测数据集的比较，调查了日本55年再分析（JRA-55）的质量，这是日本气象厅（JMA）构建的第二次全球再分析。改进了等熵面上大气环流的表示方法和基于质量加权等熵纬向平均方法的动量收支的一致性。还审查了几个区域气候变异的代表性。在热带地区，使用热带降雨测量使命多卫星降水分析估计的与降水高度空间相关的频率在JRA-55中明显高于JRA-25。结果表明，JRA-55普遍改善了在广泛的时空尺度上的现象，如赤道波，在风暴轴区域的瞬态涡旋的表示，与JRA-25在卫星时代。此外，JRA-55改善了时间的一致性相比，旧的再分析在整个再分析期间。在平流层中，我们发现在南半球（SH）冬季热带外平流层的再分析之间存在较大的差异。通过与探空资料的对比分析，发现JRA-55在1979年以前的热带外上海冬季的温度偏差小于其它再分析资料，并指出了JRA-55存在的问题。JRA-55的赤道波振幅和Madden-Julian振荡较其它再分析弱。JRA-55在南美洲和澳大利亚显示了不切实际的强冷却，尽管JRA-55中长期温度趋势的空间分布最接近全球历史地表温度的观测数据集。
This study investigates the quality of the Japanese 55-year Reanalysis (JRA-55), which is the second global reanalysis constructed by the Japan Meteorological Agency (JMA), by comparing it with other reanalyses and observational datasets. Improvements were found in the representation of atmospheric circulation on an isentropic surface and in the consistency of momentum budget based on the mass-weighted isentropic zonal mean method. The representation of climate variability in several regions was also examined. In the tropics, the frequencies of high spatial correlations with precipitation, which were estimated using the Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis, are clearly higher in JRA-55 than in JRA-25. The results indicate that JRA-55 generally improved the representations of phenomena on a wide range of space-time scales, such as equatorial waves, and transient eddies in the storm track regions, compared with JRA-25 during the satellite era. Moreover, JRA-55 improved the temporal consistency compared with the older reanalyses throughout the reanalysis period. In the stratosphere, we found larger discrepancies between reanalyses for the extra-tropical stratosphere during the Southern Hemisphere (SH) winter. Comparisons with radiosonde temperature revealed that JRA-55 has a smaller bias in temperature than the other reanalyses in the extra-tropical SH winter before 1979.Some issues in JRA-55 were also identified. The amplitude of equatorial waves and Madden-Julian oscillation in JRA-55 are weaker than in the other reanalyses. JRA-55 shows unrealistic strong cooling in South America and Australia, although the spatial distribution of the long-term temperature trends in JRA-55 is the closest to an observational dataset of global historical surface temperature.