Could artificial mountains enhance precipitation in a subtropical desert climate?

The United Arab Emirates (UAE) sit in a subtropical desert surrounded by the Arabian Gulf and the Gulf of Oman. Its climate is characterized by soaring temperatures and extreme humidity, but rare precipitation. Most of the precipitation falls during summer months when persistent and deep sea breezes impinge on the Al Hajar Mountains. Rapid economic development over the last two decades has raised governmental and business concerns about fresh water supply. Whether man-made mountains could generate or enhance regional precipitation to lessen the water supply pressure is a question often asked by the UAE policymakers and the public.

In this numerical feasibility study, Imposing artificial mountains in the region of Wathba and Muzayrah in the UAE territory, we explore the potential for orographic precipitation enhancement using the WRF and EULAG 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. Numerous simulation experiments are conducted using various mountain shapes and heights within background flows that support precipitable processes. The goal is to study both mechanical and thermodynamical effects of the imposed mountains on the prevailing sea breeze flow and on orographic precipitation. The systematic sensitivity studies involved will ultimately provide an enhanced understanding of orographic precipitation processes regardless of the viability of the mountain in the UAE environment. We will present results from these simulations, and discuss the impact of the artificial mountains on the circulation and precipitation formation.