Comparison of ECMWF analyses with GPS radio occultations from CHAMP
Comparison of ECMWF analyses with GPS radio occultations from CHAMP
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DOI：
10.5194/angeo-26-3225-2008
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发表时间：
2008-10
影响因子：
1.9
通讯作者：
T. Schmidt;J. Wickert;S. Heise;F. Flechtner;E. Fagiolini;G. Schwarz;Lieselotte Zenner;T. Gruber
中科院分区：
文献类型：
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作者：
T. Schmidt;J. Wickert;S. Heise;F. Flechtner;E. Fagiolini;G. Schwarz;Lieselotte Zenner;T. Gruber
利用2001-2007年(2001年5月至2007年12月，80个月)CHAMP无线电掩星资料，对6小时ECMWF对流层和平流层下部温度以及1000-10百帕之间的位势高度进行了气候学验证。一般来说，ECMWF和CHAMP温度之间有很好的一致性，全球年平均偏差(标准偏差)小于0.3(1.7)K，所有年份/季节的平均温度都在300-10百帕以上，区域和时间上的差异主要发生在南半球和热带对流层顶区。全球300到10百帕之间的位势高度的全球年平均偏差(标准差)在30到+5(30-50)位势米的范围内。在热带和极地地区也观察到与平均值的较大偏差。CHAMP和ECMWF之间的偏差和标准差在2006年2月和12月之前和之后都有显著差异，这两个月和12月是ECMWF将模式层数从L60增加到L91的日期(2006年2月1日)，并且ECMWF成为主要来自宇宙飞行任务的首批同化无线电掩星数据的天气中心之一(自2006年12月12日以来)。在ECMWF，CHAMP数据直到2007年2月4日才被同化，例如，在这里审议的时间段内，这两个数据集基本上彼此独立。
A climatological validation of the 6-hourly op- erational ECMWF troposphere and lower stratosphere tem- peratures as well as geopotential heights between 1000 and 10 hPa is performed using the 2001-2007 (80 months from May 2001 to December 2007) CHAMP radio occultation data. Generally there is a good agreement between ECMWF and CHAMP temperatures averaged over 300-10 hPa for all years/seasons with global annual mean biases (standard devi- ations) less than 0.3 (1.7) K. Regional and temporal discrep- ancies occur within the polar vortex mainly on the South- ern Hemisphere and the tropical tropopause region. Global annual mean biases (standard deviations) of geopotential heights between 300 and 10 hPa are in the range of 30 up to +5 (30-50) geopotential meter. Larger deviations from the mean values are also observed in the tropics and polar zones. Both, the biases and standard deviations be- tween CHAMP and ECMWF temperatures and geopoten- tial heights differ significantly before and after February and December 2006, i.e. the dates when ECMWF increased the number of model levels from L60 to L91 (1 February 2006) and where ECMWF became one of the first weather cen- ters assimilating radio occultation data (since 12 December 2006), mainly from the COSMIC mission. At ECMWF the CHAMP data were only assimilated until 4 February 2007, e.g. both data sets are mostly independent from each other during the time period considered here.