Synoptic analysis and dynamical adjustment of GEOS 3 and Seasat altimeter eddy fields in the northwest Atlantic
Synoptic analysis and dynamical adjustment of GEOS 3 and Seasat altimeter eddy fields in the northwest Atlantic
复制标题
西北大西洋GEOS 3和Seasat高度计涡流场的天气分析与动态调整
DOI：
10.1029/jc094ic05p06221
复制
发表时间：
1989
影响因子：
--
通讯作者：
Y. Ménard
中科院分区：
文献类型：
--
作者：
P. Mey;Y. Ménard
A synoptic analysis of the dynamic topography of the sea surface in a (531 km)2 domain including the sites of the Polymode Synoptic Dynamics Experiment and Local Dynamics Experiment is presented. This study is based on all available GEOS 3 and Seasat altimeter passes between May and August 1978 referenced to an altimetric mean sea surface. The altimeter synoptic time series are compared to in situ estimates calculated from Polymode expendable bathythermographs, conductivity-temperature-depth probes, deep floats, and current meters. Wherever the altimeter coverage is good, both analyses show remarkable agreement. The following results are obtained: (1) the altimeter/in situ correlation in 0.56 on average and never falls below 0.38, (2) the beginning of operations of Seasat in the first days of July 1978 has a dramatic effect on all indicators, (3) the variance for the altimeter estimate is no more than 9% higher on average than the variance of the in situ estimate, and (4) the daily mean sea level is measured to within 2.4 cm on average. A first guess of the four-dimensional stream function was calculated using the altimeter estimate at the surface and an empirical extension scheme. The resulting field was specified as initial and boundary values of the Harvard quasi-geostrophic model. It is shown that the assimilation makes the altimeter estimate converge toward the in situ estimate especially at the subthermocline levels where spatial correlations of 0.60 are achieved after 8 days. A simultaneous assimilation of the altimeter stream function and 1400-m Polymode current meter stream function was also performed, with even better results.
