CMIP5模式对近30年沃克环流强度变化模拟的不足及成因分析 *

太平洋沃克环流(Pacific Walker Circulation, PWC)是热带太平洋上空至关重要的大气环流系统, 但其在全球变暖背景下的长期变化仍存在争议, 换而言之, 沃克环流增强或减弱仍是有待回答的科学问题之一。观测表明近30年PWC呈增强趋势, 而气候模式无法得出观测的趋势。文章分析了参加第五次耦合模式比较计划(Coupled Model Inter-comparison Project Phase 5, CMIP5)的18个耦合模式模拟的PWC变化。结果表明, 大部分耦合模式能够较好地再现PWC的气候态分布特征, 但不能给出其加强的趋势。究其原因, 主要取决于模式对海表温度(SST)变化的模拟能力, 能模拟出PWC加强的耦合模式, 其模拟的SST趋势分布与观测相近[即类拉尼娜(La Niña)型], 但仍存在一定差异; 而模拟出PWC减弱的耦合模式, 其模拟的SST趋势分布表现为类厄尔尼诺(El Niño)型, 这与观测不符。对于后者, 如果用观测的SST驱动其大气模式却能够模拟出PWC的加强, 从另一方面也说明了SST变化对于PWC长期变化的主导作用。因此, CMIP5模式要想合理地预估PWC在全球变暖背景下的变化, 需要提高对于热带太平洋SST变化的模拟能力。     

赤潮数值研究的有关问题

赤潮的实质是一个海洋生态系统动力学问题，本文初步给出了描述赤潮的基本动力学方程组，并讨论了进行赤潮数值研究的必要性。数值方法既利于赤潮机理的研究又可以推动赤潮预报的发展     

海洋浮游生态系统动力学模式的研究

分析了海洋浮游生态系统动力学模式的结构,讨论了其研究现状。９０年代以来海洋浮游生态系统动力学模式的特点是：状态变量的个数较以前有所增加,从２－４个增加至３－７个生物过程的描述更加细致;注意刻画物理过程的作用,特别是垂直方向上湍流的交换作用;利用或改进原来的模式,研究新问题;模式仍以一维为主,同时三维耦合模式也得取发展和应用;区域仍以北大西洋为主,也出现了研究赤道太平洋、阿拉伯海、东海等海区的工作。     

Oscillation in frequency of tropical cyclones passing Taiwan and Hainan Islands and the relationship with summer monsoon

The temporal variations in the frequency of tropical cyclones (TCs) traversing the Taiwan and Hainan Islands (TH islands), were analyzed using a best-track TC dataset from the Joint Typhoon Warning Center for the period 1945-2007. Results show that the oscillations were interannual and interdecadal on the timescales of 2-8 and 8-12 years, respectively. It is also shown that the number of TCs formed in the western North Pacific basin (WNP) and of those traversing the TH islands varied intraseasonally. These results also held for typhoons traversing the TH islands, although the oscillations were less apparent. This study identified interrelationships between the frequency of TCs making landfall on the TH islands and the East Asia summer monsoon (EASM), the South Asia summer monsoon (SASM), and the South China Sea summer monsoon (SCSSM). The SCSSM significantly influenced the number of TCs traversing Hainan Island, but had little influence on the number of TCs traversing Taiwan Island. By contrast, the SASM influenced the numbers of TCs traversing both of the TH islands, shown by correlation coefficients of 0.41 for Taiwan Island and -0.25 for Hainan Island. In addition, the frequency of TC landfall on Taiwan Island increased during years of enhanced EASM, as indicated by a correlation coefficient of 0.4.