东中国海HYCOM模式垂向坐标对比研究

A comparative study of HYCOM vertical coordinate in the East China Sea

基于挪威南森环境遥感中心改进的NERSC-HYCOM模式,利用单向嵌套技术与欧洲中心提供的2008年ERA-I高分辨率强迫场针对东中国海及其邻近海区进行了不同垂向坐标配置的四个敏感性试验。通过分析东中国海区域的温度、盐度,流速的分布和变化,探讨了HYCOM模式中不同垂向坐标设置对东中国海近岸区域的影响以及黑潮流速及路径对不同坐标设置的响应,期望对HYCOM模式更深入的研究提供参考。结果表明:(1)在东中国海区上层并不适于采用等密度坐标方案,也就是说应该采用z坐标或σ坐标用以表征此处混合层的季节性变化特征;(2)针对东海大陆架区给出了10个位置上的模式与浮标观测资料的温、盐平均误差(ME)、均方根差(RMS)及相关系数(R)指标,发现对于不同区域,每种试验的适用性都不同;(3)使用高频资料时,模拟的流速普遍偏高,东海黑潮冬夏路径的异同指出了σ-z-iso与z-iso试验模拟效果较好,但模拟的日本岛南岸的弯曲流场位置偏南;而z-only试验模拟的日本岛以南的黑潮路径是有所改观的,z坐标的分辨率对表层的黑潮路径影响很大;σ-only试验模拟的整个黑潮路径的效果最差。

Based on Norway Nansen environment remote sensing center improved NERSC-HYCOM model using unidirectional double nested technology and 2008 ERA-I high frequency force field, four sensitivity tests were made in the East China Sea area. The purpose of this paper is to study the impact of HYCOM patterns in different vertical coordinate settings on nearshore area of the East China Sea, and the influence of the Kuroshio flow velocity and path for the response of different coordinate settings. It is expected to provide the reference of further research on HYCOM mode through the analysis of surface temperature, salinity, and distribution and variation of flow field. The results indicate that： （1） the upper layer of the East China Sea is not suitable for density coordinate, which means it should use z coordinates or a coordinates to characterize the seasonal variation of the mixed layer here; （2） in the continental shelf area of the East China Sea, the average error （ME）, the root mean square differences （RMS） and correlation coefficient （R） indicators of temperature and salt between ARGO and tests are given for 10 buoy point and finally found that the applicability of each test is different in different regions; （3） when using high-frequency data, the simulated flow rate is generally high, differences in the path and maximum flow rate of four tests in summer and winter point that a-z-iso and z-iso tests have better simulations, but position of the simulated Big Bend area of the Kuroshio is southerly, and for the z-only test, the path of the Kuroshio in south of the Japan Island has changed. It can concluded that the z coordinate resolution has an important impact on the surface of the Kuroshio path. Finally, for the a-only test, there is the worst simulation of the entire Kuroshio path.