Can current reanalyses accurately portray changes in Southern Annular Mode structure prior to 1979?
Can current reanalyses accurately portray changes in Southern Annular Mode structure prior to 1979?
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DOI：
10.1007/s00382-022-06292-3
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发表时间：
2022-04-29
期刊：
影响因子：
4.6
通讯作者：
Clem, Kyle R.
中科院分区：
文献类型：
--
作者：
Marshall, Gareth J.;Fogt, Ryan L.;Clem, Kyle R.
早期的再分析对于调查臭氧消耗对南半球高纬度气候的区域影响来说并不是最佳的，因为1979年以来卫星探测器数据的可用性大大提高了数据稀疏区域的准确性，导致了一致的不均匀性。为了确定当前的再分析是否在卫星出现前的SH高纬度地区更好，在这里我们检查了欧洲中期天气预报中心（ECMWF）第五代再分析（ERA 5），二十世纪世纪再分析版本3（20 CRv 3），和日本气象厅（JMA）55年再分析（JRA-55），以再现和帮助解释南方环形模态（SAM）之间关系的显著变化1950 - 1979年（早期）和1980-2020年（晚期）的南极近地表气温（SAT）。我们发现，ERA 5最好地再现南极SAT在早期，也是最均匀的再分析跨越早期和晚期。ERA 5和20 CRv 3在这两个时期都提供了SAM的良好代表性，而JRA-55仅在晚期时期具有类似的技巧。然而，所有三个再分析表明，南极SAM-SAT的关系显着变化的两个时期之间。特别是，ERA 5和20 CRv 3证明了在南极半岛观测到的SAM-SAT关系符号的转换：SAM结构变化和相关纬向风异常的分析表明，在这些再分析中，正SAM与早期的寒冷南风和晚期的温暖北风有关，从而为区域SAM-SAT关系逆转提供了一个简单的解释。
Early reanalyses are less than optimal for investigating the regional effects of ozone depletion on Southern Hemisphere (SH) high-latitude climate because the availability of satellite sounder data from 1979 significantly improved their accuracy in data sparse regions, leading to a coincident inhomogeneity. To determine whether current reanalyses are better at SH high-latitudes in the pre-satellite era, here we examine the capabilities of the European Centre for Medium-range Weather Forecasts (ECMWF) fifth generation reanalysis (ERA5), the Twentieth Century Reanalysis version 3 (20CRv3), and the Japanese Meteorological Agency (JMA) 55-year reanalysis (JRA-55) to reproduce and help explain the pronounced change in the relationship between the Southern Annular Mode (SAM) and Antarctic near-surface air temperatures (SAT) between 1950 and 1979 (EARLY period) and 1980-2020 (LATE period). We find that ERA5 best reproduces Antarctic SAT in the EARLY period and is also the most homogeneous reanalysis across the EARLY and LATE periods. ERA5 and 20CRv3 provide a good representation of SAM in both periods with JRA-55 only similarly skilful in the LATE period. Nevertheless, all three reanalyses show the marked change in Antarctic SAM-SAT relationships between the two periods. In particular, ERA5 and 20CRv3 demonstrate the observed switch in the sign of the SAM-SAT relationship in the Antarctic Peninsula: analysis of changes in SAM structure and associated meridional wind anomalies reveal that in these reanalyses positive SAM is linked to cold southerly winds during the EARLY period and warm northerly winds in the LATE period, thus providing a simple explanation for the regional SAM-SAT relationship reversal.