Influences of the monsoon trough and Arabian heat low on summer rainfall over the United Arab Emirates

The simulations show associations between active phases of the southwest Asian monsoon and intensification of the Arabian heat low, leading up to UAE rainfall events. Variability in the location and strength of the Arabian heat low circulation, which differs from the static portrayal in climatological minimum sea level pressure (MSLP), can affect the development of deep convection over the UAE.

Analysis of the vorticity equation for a two-day case study period confirms that convergence is solely responsible for the spinup and maintenance of the primary heat low circulation. Convergence is also responsible for the spinup of a separate cyclonic circulation over the eastern UAE, which propagates offshore to the Arabian Gulf during morning hours. This cyclonic circulation advects moist air onshore over the western UAE, and deep convection follows from inland horizontal convective rolls and interaction with the approaching sea-breeze front.