摘要
采用Stevens开边界条件,将一个闭边界海盆尺度环流模式改造成开边界模式,对20°S以北太平洋大尺度环流进行了系统模拟。考察了开边界和不同等密面扩散系数对北太平洋环流和温盐结构的影响。模式较好地再现了太平洋大尺度环流特征,模拟出了表层赤道流系(包括北赤道流、黑潮和北太平流)以及对应的顺时针环流,同时还较好地反映了温盐场的基本分布特征。从年平均的纬向平均温度和盐度的断面分布可以看出,温跃层深度呈“W”型分布,在亚极地海区有一个梯度比较大的盐度锋区。南边界打开后使得模拟的北太平洋中层水温度和盐度更低,低盐水舌加深和向南延伸加强,更加接近观测值。增加沿等密面扩散系数后得到的中层水强度更大,尤其是34.6等盐线更接近观测资料。质量输运流函数分布表明,赤道两边各有一个翻转区,亚极地地区也存在一个浅的翻转区,打开南边界可以消除因为闭边界存在产生的假的下沉流,这些都为将来进行示踪物模拟打下基础。
In this paper, the Stevens open boundary conditions are used to change a basinwide scale closed boundary circulation model into an open boundary model, and the open boundary model is then used to simulate the large-scale circulation system in the North Pacific north of 20 °S. The effects of open boundary and different isopycnal diffusion coefficients on the circulation and thermohaline structure in the North Pacific are examined. The model can well reproduce the large scale circulation features in the North Pacific, the simulated results show the surface equatorial current system （including the North Equatorial Current, the Kuroshio and the North Pacific Current） and the corresponding clockwise gyre, and reflect the basic thermohaline distribution features. It is shown from the annual mean zonally averaged temperature and salinity distributions that the thermocline depths show a W-shaped pattern , and there is a salinity front in the subpolar sea area. The opening of south boundary makes the simulated temperature and salinity of the North Pacific Intermediate Water lower and the low salinity water tongue deeper to extend southward, so the simulated results with open boundary conditions are closer to the observations. The increase in the isopycnal diffusion coeficient makes the North Pacific Intermediate Water stronger, and especially makes the 34.6 isohalines closer to the observations. It is shown from the meridional mass transport stream function distributions that there are two overturn cells, one on each side of equator, and there is another shallow overturn cell in the subpolar sea area. The opening of south boundary can eliminate the false downwelling caused by the existence of closed boundary, which will provide basis for simulating the passive tracers in the future.
出处
《海洋科学进展》
CAS
CSCD
北大核心
2006年第3期292-300,共9页
Advances in Marine Science
基金
国家自然科学基金项目---北太平洋人为二氧化碳的海气通量的模式研究(40145023)
中科院知识创新工程重大项目---近海生态系统碳循环模型研究(KZCX1-SW-01-16)
中国科学院引进国外杰出人才计划---全球环境变化:碳循环研究
关键词
北太平洋
海盆尺度
环流模式
开边界
North Pacific
basinwide scale
circulation model
open boundary
