Impact of Ocean-Continent Distribution over Southern Asia on the Formation of Summer Monsoon
Impact of Ocean-Continent Distribution over Southern Asia on the Formation of Summer Monsoon
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作者：
Zhu Congwen
利用CCM3/NCAR模式，设计了一系列数值试验，研究了非洲-阿拉伯海-印度半岛-孟加拉湾(BOB)-印度-中国半岛-南中国海陆交错分布对亚洲夏季风环流形成的影响。结果表明，非洲或印度次大陆与印度洋、阿拉伯海和BOB部分地区的热力差异是维持印度季风环流的主要机制。在去除这两个大陆的实验中，印度季风系统(IMS)的成员，即索马里越赤道急流(40°E)和阿拉伯海和鲍勃上空的西南风季风几乎消失。此外，哈德利环流的减弱占主导地位。这也证明了非洲比印度次大陆对IMS的影响更大。然而，印度-中国半岛和澳大利亚的存在加强了东亚季风系统。印度-中国半岛与南海、澳大利亚与西太平洋之间的热力差异对东亚夏季风以南热带季风的形成起着重要作用。当中南半岛被遮蔽时，越赤道气流(105°E和125°E)消失，东亚地区常见的西南季风也消失，东亚夏季风明显减弱。此外，还研究了这些温差对夏季降水和地表温度分布的影响。
Using the CCM3/NCAR, a series of numerical experiments are designed to explore the effect of ocean-land interlaced distributions of Africa-Arabian Sea-India Peninsula-Bay of Bengal (BOB)-Indo-China Peninsula-South China Sea on the formation of the Asian summer monsoon circulation (ASMC). The results show that the thermal difference between African or Indian Subcontinent and nearby areas including the Indian Ocean, Arabian Sea, and part of BOB is the primary mechanism that maintains the Indian monsoon circulation. In the experiment getting rid of these two continents, the Indian monsoon system (IMS) members, i.e., the Somali cross-equatorial jet (40°E) and the southwesterly monsoon over the Arabian Sea and BOB, almost disappear. Moreover, the Hadley circulation weakens dominantly. It also proves that Africa has greater effect than Indian Subcontinent on the IMS. However, the existence of Indo-China Peninsula and Australia strengthens the East Asian monsoon system (EAMS). The thermal contrast between Indo-China Peninsula and SCS, Australia and western Pacific Ocean plays an important role in the formation of the tropical monsoon to the south of the EAMS. When the Indo-China Peninsula is masked in the experiment, the cross-equatorial flow (105°E and 125°E) vanishes, so does the southwesterly monsoon usually found over East Asia, and EAMS is enfeebled significantly. In addition, the impacts of these thermal contrasts on the distribution of the summer precipitation and surface temperature are investigated.