Wind field differences between three meteorological reanalysis data sets detected by evaluating atmospheric excitation of Earth rotation
Wind field differences between three meteorological reanalysis data sets detected by evaluating atmospheric excitation of Earth rotation
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通过评估地球自转的大气激励检测到的三个气象再分析数据集之间的风场差异
DOI：
10.1029/2007jd008893
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发表时间：
2008
影响因子：
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通讯作者：
Y. Masaki
中科院分区：
文献类型：
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作者：
Y. Masaki
我们比较了1979 - 2001年23年间NCEP/NCAR、NCEP- doe和ERA-40三个不同气象再分析数据集计算的地球自转变化的大气激励。大气激励用大气角动量（AAM）函数来计算。我们发现，AAM函数的差异主要是由于三个再分析数据集之间风数据的差异，特别是北风数据的差异。NCEP- doe与ERA-40 AAM功能的差异大于NCEP/NCAR与NCEP- doe之间的差异。对赤道AAM功能有较大影响的北风差异来自南半球热带和中纬度地区的对流层上层，特别是在拉丁美洲以东的东太平洋、非洲和印度洋三个区域。在南半球的中纬度地区可以看到东风的差异。这些差异并不局限于单一的频率。差谱显示出淡红色的频率依赖性，在季节带和潮汐日带中有一些峰值。由于热带地区的东风和北风分别能最有效地改变地球的自旋速率和极地运动，因此热带地区的风精度直接决定了大气激励评估的准确性。
[1] We compared atmospheric excitations of the varying Earth rotation calculated from three different meteorological reanalysis data sets (NCEP/NCAR, NCEP-DOE and ERA-40) over 23 years, from 1979 to 2001. Atmospheric excitations are evaluated by atmospheric angular momentum (AAM) functions. We found that differences in AAM functions are primarily caused by differences in the wind data, especially the northward wind data, between the three reanalysis data sets. Differences between the NCEP-DOE and ERA-40 AAM functions are larger than those between the NCEP/NCAR and NCEP-DOE ones. The northward wind differences that have a large effect on the equatorial AAM functions originate from the upper troposphere at the tropics and midlatitudes in the southern hemisphere, especially in three regions: east Pacific off Latin America, Africa and the Indian Ocean. The eastward wind differences are seen at midlatitudes in the southern hemisphere. These differences are not confined to a single frequency. The difference spectra show a reddish frequency dependence with some peaks in seasonal bands and tidal diurnal bands. Since the eastward and northward winds over the tropics can most efficiently change the Earth's spin rate and polar motion, respectively, the wind accuracy over the tropics directly determines the accuracy in evaluations of the atmospheric excitations.