The ECMWF reanalysis of the MAP Special Observing Period
The ECMWF reanalysis of the MAP Special Observing Period
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ECMWF 对 MAP 特别观测期的重新分析
DOI：
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发表时间：
2004
期刊：
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通讯作者：
C. Cardinali
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作者：
C. Keil;C. Cardinali
欧洲中期天气预报中心 (ECMWF) 对中尺度高山计划 (MAP) 特别观测期（1999 年 9 月 7 日至 11 月 15 日）进行了重新分析。全球资料同化系统4D-Var（T511/159L60，水平分辨率约40公里）的大幅升级结合专项MAP观测，为山地大气现象研究提供了新的参考描述。 MAP 再分析中使用的 MAP 观测包括欧洲风廓线仪、高分辨率无线电探空仪和地面观测。 MAP 观测结果的同化导致中欧上空的气旋流和阿尔卑斯地区上空的对流层中层西风略有减弱。此外，MAP 观测结果导致阿尔卑斯山南部地区、法国南部和亚得里亚海的气候变得更加潮湿。将 MAP 再分析预测的日降雨量与波河流域观测到的平均降水量进行比较，结果显示在时间和降雨量方面具有良好的一致性。对一些强化观察期 (IOP) 的调查说明了 MAP 再分析的具体方面。很好地捕获了不同流态的不同降水模式特征（IOP2b 和 IOP8）。风廓线仪的同化可纠正发散的风场，但由于湿度分析的执行方式（2003 年 ECMWF 引入了修改的湿度分析），变化可能会错误地反馈到湿度场 (IOP2a)。使用独立于模型的全球定位系统 (GPS) 得出的综合水蒸气含量进行的验证表明，湿度场很好地描述了南高山 GPS 站的日间湿度变化。然而，与 GPS 测量相比，重新分析似乎有点过于干燥。版权所有 © 2004 英国皇家气象学会
A reanalysis of the Mesoscale Alpine Programme (MAP) Special Observing Period (7 September to 15 November 1999) was performed at the European Centre for Medium‐Range Weather Forecasts (ECMWF). Substantial upgrades in the global data assimilation system 4D‐Var (T511/159L60, horizontal resolution approximately 40 km) combined with special MAP observations provide a new reference description for studies on mountain‐related atmospheric phenomena. The MAP observations used in the MAP reanalysis comprise European windprofilers, high‐resolution radiosondes and surface observations. The assimilation of MAP observations results in a slight weakening of the cyclonic flow over central Europe and of the mid‐tropospheric westerly wind over the Alpine region. Also, MAP observations lead to moister conditions in the southern Alpine region, southern France and over the Adriatic Sea. The comparison of forecast daily rainfall from the MAP reanalysis with observed precipitation totals averaged over the Po catchment shows good agreement in timing and rain amount. Investigations of some Intensive Observation Periods (IOPs) illustrate specific aspects of the MAP reanalysis. Different precipitation patterns characteristic of different flow regimes are well captured (IOP2b and IOP8). The assimilation of windprofilers rectifies the divergent wind field, but changes can erroneously feed back on the humidity field (IOP2a) because of the way the humidity analysis is performed (a modified humidity analysis was introduced at ECMWF in 2003). Validation with model‐independent Global Positioning System (GPS) derived integrated water‐vapour contents shows that the humidity field describes well the inter‐diurnal humidity variations at southern Alpine GPS stations. However, the reanalysis appears to be slightly too dry compared with GPS measurements. Copyright © 2004 Royal Meteorological Society