Colder Subarctic Pacific with larger sea ice caused by closure of the Central American Seaway and its influence on the East Asian monsoon: a climate model study
Tatsuo Motoi, Wing-Le Chan, 2010. "Colder Subarctic Pacific with larger sea ice caused by closure of the Central American Seaway and its influence on the East Asian monsoon: a climate model study", Monsoon Evolution and Tectonic–Climate Linkage in Asia, P. D. Clift, R. Tada, H. Zheng
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The changes in the sea-ice conditions and sea surface temperatures in the Subarctic Pacific caused by the closure of the Central American Seaway and their influence on the East Asian monsoon are investigated by a series of closed (CE), open (OE) and re-closed (RCE) seaway experiments with a climate model. It is found that a permanent halocline forms in the Subarctic Pacific because of the termination of saline water transport through the seaway in CE and RCE. Efficient cooling by shallow convection in the stratified permanent halocline causes thicker and more extensive sea ice in winter, and leads to colder surface water in summer in the Subarctic Pacific.
Colder air, over more extensive sea ice cover in winter and over the colder water in summer, produces higher surface air pressure with anticyclonic wind anomalies in both seasons. Southeasterly and southerly wind anomalies develop around the Japanese archipelago in the East Asian monsoon region and induce warm and humid surface air with increased precipitation over the East Asian continent. These results indicate that the East Asian monsoon is weakened in winter and strengthened in summer as a result of closing the Central American Seaway.
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Monsoon Evolution and Tectonic–Climate Linkage in Asia
The Earth’s climate varies through geological time as a result of external, orbital processes, as well as the positions of continents, growth of mountains and the opening and closure of oceanic gateways. Climate modelling suggests that the intensity of the Asian monsoon should correlate, at least in part, with the uplift history of the Tibetan Plateau and the Himalaya, as well as the evolution of gateways and the retreat of shallow seas in Central Asia. Long-term reconstructions of both mountain building and monsoon activity are key to testing the proposed links. This collection of papers presents a series of new studies documenting the variations of the Asian monsoon on orbital and tectonic timescales, together with the impact this has had on environmental conditions. The issue of which proxies are best suited to measuring monsoons is addressed, as is the effect that the monsoon has had on erosion and the formation of the stratigraphic record both on and offshore.