The Reliability of Antarctic Tropospheric Pressure and Temperature in the Latest Global Reanalyses
The Reliability of Antarctic Tropospheric Pressure and Temperature in the Latest Global Reanalyses
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DOI：
10.1175/jcli-d-11-00685.1
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发表时间：
2012-10-15
影响因子：
4.9
通讯作者：
Marshall, Gareth J.
中科院分区：
文献类型：
--
作者：
Bracegirdle, Thomas J.;Marshall, Gareth J.
在这项研究中，将南极观测站的地面和无线电探空数据与跨越1979-2008年的五个再分析[气候预测系统再分析(CFSR)、40年ECMWF再分析(ERA-40)、ECMWF中期再分析(ERA-临时)、日本25年再分析(JRA-25)和现代研究与应用回顾分析(MERRA)]的输出进行了比较。对四个变量：平均海平面气压(MSLP)、近地表气温(T-S)、500百帕位势高度(H-500)和500百帕温度(T-500)进行了再分析和观测之间的偏差和年际相关性的评估。结果表明，CFSR和MERRA具有足够高的分辨率，足以在沿海观测站准确地再现地形高度。对于再分析来说，这些沿海站的负T-S偏差越来越大，按分辨率递减的顺序是明显的。然而，地形高度偏差不能解释CFSR中较大的冬季温暖偏差。在阿蒙森-斯科特和沃斯托克的JRA-25和MERRA(分别为11.1度、10.2度和7.9摄氏度)，这与表示表面能量平衡的问题有关。南极作为一个整体的年平均T-500和H-500的线性趋势被发现在CFSR、ERA-TIMATION和MERRA中最可靠，这些在1979-2008年间都没有显示出显著的趋势。相比之下，JRA-25在1979-2008年期间显示出明显的负面趋势，ERA-40在1980年代显示出显著的积极趋势(在T-500和H-500中都很明显)。与观测结果的比较表明，ERA-40的积极趋势是虚假的。在单个站点的较小空间尺度上，所有五个再分析都有一些虚假的趋势。然而，ERA-临时被发现是最可靠的MSLP和H-500趋势在站点位置。
In this study, surface and radiosonde data from staffed Antarctic observation stations are compared to output from five reanalyses [Climate Forecast System Reanalysis (CFSR), 40-yr ECMWF Re-Analysis (ERA-40), ECMWF Interim Re-Analysis (ERA-Interim), Japanese 25-year Reanalysis (JRA-25), and Modern Era Retrospective-Analysis for Research and Applications (MERRA)] over three decades spanning 1979-2008. Bias and year-to-year correlation between the reanalyses and observations are assessed for four variables: mean sea level pressure (MSLP), near-surface air temperature (T-s), 500-hPa geopotential height (H-500), and 500-hPa temperature (T-500).It was found that CFSR and MERRA are of a sufficiently high resolution for the height of the orography to be accurately reproduced at coastal observation stations. Progressively larger negative T-s biases at these coastal stations are apparent for reanalyses in order of decreasing resolution. However, orography height bias cannot explain large winter warm biases in CFSR. JRA-25, and MERRA (11.1 degrees, 10.2 degrees, and 7.9 degrees C, respectively) at Amundsen-Scott and Vostok, which have been linked to problems with representing the surface energy balance.Linear trends in the annual-mean T-500 and H-500 averaged over Antarctica as a whole were found to be most reliable in CFSR, ERA-Interim, and MERRA, none of which show significant trends over the period 1979-2008. In contrast JRA-25 shows significant negative trends over 1979-2008 and ERA-40 gives significant positive trends during the 1980s (evident in both T-500 and H-500). Comparison to observations indicates that the positive trend in ERA-40 is spurious. At the smaller spatial scale of individual stations all five reanalyses have some spurious trends. However, ERA-Interim was found to be the most reliable for MSLP and H-500 trends at station locations.