Impact of the insolation seasonal asymmetry on the tropical precipitation during the mid-Holocene
Date Issued
2007
Date
2007
Author(s)
Hsu, Yang-Hui
DOI
en-US
Abstract
A series of model experiments were conducted using an intermediate ocean-atmosphere-land model for better understanding how the tropical climate responds to asymmetric insolation forcing during the Mid-Holocene, 6ka. During the mid-Holocene, summer insolation at high latitudes of Northern hemisphere is stronger than that in the present due to a larger obliquity, while winter insolation in the tropics is weaker due to the precessional shift of perihelion relative to vernal equinox. The solar forcing presents both spatial and seasonal asymmetric patterns.
However, the precipitation response does not necessarily follow the insolation forcing patterns of different seasons. Our analysis indicates that ocean feedback plays an important role in regulating the tropical precipitation. The solar forcings are cancelled out by the surface heat flux from the slow-responding ocean to the warming or cooling brought about by insolation changes one or two seasons ago. The northward shift of the Asian summer monsoon rain belt, which is widely found in numerous proxy records, is enhanced by the increased land-sea thermal contrast. Enhanced precipitation is caused by energy fluxes over ocean in boreal summer, resulting in a pronounced latitudinal land-sea contrast in the pattern of precipitation changes.
Subjects
中全新世
日照量
氣候模式
mid-Holocene
insolation forcing
model experiment
SDGs
Type
thesis
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