The influence of lapse rate and moist static energy budget on the vertical structure of the ITCZ

Recent observations have shown that shallow meridional circulation (SRF) is a salient feature of the ITCZ in the east Pacific. The south Asian monsoon region is characterized by presence of two ITCZ, one near equator and another off-the equator. The equatorial ITCZ has a shallow meridional circulation but the off-equatorial ITCZ has deep meridional circulation.

We have used an atmospheric general circulation model (CAM 3.1) with an aqua planet configuration to understand the factors that cause differences in vertical structure between equatorial and off-equatorial ITCZ . We specify the zonally symmetric meridional variation of SST that is similar to observations at 90o E. We show that lapse rate changes and moist static energy budget play an important role in influencing the vertical structure of the ITCZ.