A Numerical Study of the Arabian Gulf Sea Breeze Interactions with Topographic Flows

The United Arab Emirates (UAE) sits in a subtropical desert surrounded by the Arabian Gulf and the Gulf of Oman. The arid climate is characterized by soaring temperatures and high humidity, but rare precipitation. Precipitation can either occur during the winter when frontal systems traverse the region or during the summer when persistent and deep sea breezes impinge on the Al Hajar Mountains and trigger connective rainfall. Rapid economic development and population growth over the last two decades have raised concern about sustained water security. There is a growing interest from the government and business community whether artificial hills would enhance rainfall and pleasant climate.

In this numerical study, imposing artificial hills in the region of Wathba and Muzayrah in the UAE territory, we investigate the interaction between topographic flows and thermodynamic sea breeze circulations using WRF and CM1 models. Both models solve the fully time-dependent equations of atmospheric dynamics and thermodynamics, and can realistically represent effects related to land-sea contrasts, transient interactions between storms and mountains, and nonlinearity of blocking and microphysics. Idealized 2D and 3D experiments are designed and conducted to understand both mechanical and thermodynamical effects of the imposed mountains on the prevailing sea breeze flow and on orographic precipitation. Analysis is focused on the changes in sea breeze onset, duration, extent and strength, and the potential for orographic precipitation enhancement under various mountain shapes and heights and different background flows and land-sea thermo contracts. We will present results from these simulations, and discuss the impact of the artificial mountains on the coastal circulation and precipitation formation.