Ag. Dai et al., Climate changes in the 21st century over the Asia-Pacific region simulatedby the NCAR CSM and PCM, ADV ATMOS S, 18(5), 2001, pp. 639-658
The Climate System Model (CSM) and the Parallel Climate Model (PCM), two co
upled global climate models without flux adjustments recently developed at
NCAR, were used to simulate the 20th century climate using historical green
house gas and sulfate aerosol forcing. These simulations were extended thro
ugh the 21st century under two newly developed scenarios, a business-as-usu
al case (BAU, CO(2)approximate to 710 ppmv in 2100) and a CO2 stabilization
case (STA550, CO(2)approximate to 540 ppmv in 2100). The simulated changes
in temperature, precipitation, and soil moisture over the Asia-Pacific reg
ion (10 degrees -60 degreesN, 55 degrees -155 degreesE) are analyzed, with
a focus on the East Asian summer monsoon rainfall and climate changes over
the upper reaches of the Yangtze River.
Under the BAU scenario, both the models produce surface warming of about 3-
5 degreesC in winter and 2-3 degreesC in summer over most Asia. Under the S
TA550 scenario, the warming is reduced by 0.5-1.0 degreesC in winter and by
0.5 degreesC in summer. The warming is fairly uniform at the low latitudes
and does not induce significant changes in the zonal mean Hadley circulati
on over the Asia-Pacific domain. While the regional precipitation changes f
rom single CSM integrations are noisy, the PCM ensemble mean precipitation
shows 10%-30% increases north of similar to 30 N and similar to 10% decreas
es south of similar to 30 degreesN over the Asia-Pacific region in winter a
nd 10%-20% increases in summer precipitation over most of the region. Soil
moisture changes are small over most Asia. The CSM single simulation sugges
ts a 30% increase in river runoff into the Three Gorges Dam, but the PCM en
semble simulations show small changes in the runoff.