Effect of high-resolution SST on East Asian summer monsoon and tropical cyclone activity in a 60-km AGCM
Tomomichi Ogata, Ryo Mizuta, Kohei Yoshida
Received 2016/07/19, Accepted 2016/10/21, Published 2016/11/30
Tomomichi Ogata1), Ryo Mizuta2), Kohei Yoshida2)
1) Faculty of Life and Environmental Sciences, University of Tsukuba
2) Meteorologial Research Institute
This study uses an atmospheric general circulation model (AGCM), with a resolution of 60 km, to investigate the effect of high-horizontal-resolution SST data on simulations of elements of the East Asian summer monsoon (EASM), including the northwestern Pacific subtropical high (NWPSH) and tropical cyclone (TC) genesis. Plotting the result of the fine-resolution (60 km) minus coarse-resolution (300 km) SST AGCM runs shows a low-level anticyclonic anomaly (with suppressed convective activity) over the northwestern Pacific (NWP) following the onset of the NWP monsoon (July–September). In addition, TC frequency and mean TC intensity are controlled by the atmospheric circulation change that is related to the NWPSH. Changes in environmental parameters can partly explain these TC frequency and intensity changes. Based on the similarity between the realistic and idealized SST experiments, the cold SST anomaly around 10–15°N seems to play a key role in the low-level anticyclonic anomaly. Analysis of the ocean circulation and heat budget reveals that advection of cold water from the central Pacific by the westward-flowing North Equatorial Current (NEC) is important for the development of this cold SST anomaly.
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