Intercomparison of the seasonal cycle of tropical surface stress in 17 AMIP atmospheric general circulation models
Intercomparison of the seasonal cycle of tropical surface stress in 17 AMIP atmospheric general circulation models
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17个AMIP大气环流模式热带表面应力季节周期的对比
DOI：
10.1007/s003820050183
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
B. Goswami
中科院分区：
文献类型：
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作者：
N. Saji;B. Goswami
热带大气的平均状态是重要的，因为海洋和大气之间的耦合性质非线性地依赖于耦合系统的基本状态。对17个大气环流模式（AGCM）对热带地面风应力年循环的模拟进行了检验和比较。所考虑的模型是大气模型相互比较项目（AMIP）的一部分，并与1979-1988年十年的观测海表温度（SST）相结合。已经制定了几项措施，以相互比较全球热带和区域尺度上的17个模型的性能。在观测不确定性的范围内，所研究的模型模拟了真实的热带地区平均纬向和纬向年平均应力。这是一个值得注意的改进，旧一代的低分辨率模式，指出其模拟的表面应力大大低于观察。该模型还模拟了现实的大小的空间分布的年平均表面应力场，并被认为是逼真地再现其观察到的空间格局。在年方差场的模拟中也观察到类似的特征。除了少数几个热带地区外，模型在几乎所有热带地区都表现良好。其中，索马里上空的模拟很有趣。在这一地区，模型被认为低估了年平均纬向和纬向应力。在模拟这些数量方面，不同模型之间也存在很大差异。在赤道印度洋、中南部太平洋、东北太平洋和赤道东太平洋的年平均纬向应力场的模拟中也发现了较大的模式间差异。结果表明，模拟地面风场的系统误差与模拟热带辐合带的位置和强度的系统误差有关。索马里上空大多数模式模拟的年平均西南风弱于观测，这是由于北方半球夏季西南风弱于观测。这与北方夏季大多数模式模拟的陆地降水弱于观测有关。对索马里和赤道印度洋海面风场模拟的差异性与AGCM对这两个区域降水带模拟的差异性有关。
The mean state of the tropical atmosphere is important as the nature of the coupling between the ocean and the atmosphere depends nonlinearly on the basic state of the coupled system. The simulation of the annual cycle of the tropical surface wind stress by 17 atmospheric general circulation models (AGCMs) is examined and intercompared. The models considered were part of the Atmospheric Model Intercomparison Project (AMIP) and were integrated with observed sea surface temperature (SST) for the decade 1979–1988. Several measures have been devised to intercompare the performance of the 17 models on global tropical as well as regional scales. Within the limits of observational uncertainties, the models under examination simulate realistic tropical area-averaged zonal and meridional annual mean stresses. This is a noteworthy improvement over older generation low resolution models which were noted for their simulation of surface stresses considerably weaker than the observations. The models also simulate realistic magnitudes of the spatial distribution of the annual mean surface stress field and are seen to reproduce realistically its observed spatial pattern. Similar features are observed in the simulations of the annual variance field. The models perform well over almost all the tropical regions apart from a few. Of these, the simulations over Somali are interesting. Over this region, the models are seen to underestimate the annual mean zonal and meridional stresses. There is also wide variance between the different models in simulating these quantities. Large model-to-model variations were also seen in the simulations of the annual mean meridional stress field over equatorial Indian Ocean, south central Pacific, north east Pacific and equatorial eastern Pacific oceans. It is shown that the systematic errors in simulating the surface winds are related to the systematic errors in simulating the Inter-Tropical Convergence Zone (ITCZ) in its location and intensity. Weaker than observed annual mean southwesterlies simulated by most models over Somali is due to weaker than observed southwesterlies during the Northern Hemisphere summer. This is related to the weaker than observed land precipitation simulated by most models during the Northern Hemisphere summer. The diversity in simulation of the surface wind over Somali and equatorial Indian ocean is related to the diversity of AGCMs in simulating the precipitation zones in these regions.