北太平洋经向翻转环流季节变异机制的模拟研究

Numerical Study on the Mechanism of Seasonal Variation of Meridional Overturning Circulation in the North Pacific

北太平洋经向翻转环流(NPMOC)是北太平洋所有经向翻转环流圈的总称。其中,热带环流圈(TC)、副热带环流圈(STC)和深层热带环流圈(DTC)位于北太平洋热带-副热带海域,是该海域经向物质和能量交换的重要通道。基于NEMO模式分别对TC、STC和DTC经向流量的季节变化特征和机理进行了模拟研究,驱动场增强和减弱情况下的敏感性试验表明,风应力是TC和STC南、北向输送以及DTC南向输送季节变化的主要影响因素,而热通量和淡水通量的影响较小;风应力和热盐通量季节变化情况下的敏感性试验表明,TC和STC的南、北向输送以及DTC的南向输送主要是由风应力的季节振荡引起的,而热通量和淡水通量的影响较小。

The North Pacific meridional overturning circulation（NPMOC）is the general name of all the North Pacific overturning cells.The tropical cell（TC）,subtropical cells（STC）and deep tropical cell（DTC）located in the tropical-subtropical region of the North Pacific are very important for meridional material and energy exchange.The mechanisms of seasonal variation of TC,STC and DTC meridional transports are studied with the NEMO model in this paper.Numerical experiments with strengthened and weakened forcing fields show that the wind stress plays an important role in seasonal variations of southward and northward transports of TC and STC and southward transport of DTC,heat flux and freshwater flux,however,have much weaker influences.Numerical experiments of the wind stress and heat-salt transport reveal that the seasonal changes in the wind stress is the key factor of the seasonal variation of NPMOC,while the heat and freshwater fluxes play a minor role.