Estimation of the Heat and Water Budgets of the Persian (Arabian) Gulf Using a Regional Climate Model*,+

Abstract

Because of the scarcity of observational data, existing estimates of the heat and water budgets of the Persian Gulf are rather uncertain. This uncertainty leaves open the fundamental question of whether this water body is a net heat source or a net heat sink to the atmosphere. Previous regional modeling studies either used specified surface fluxes to simulate the hydrodynamics of the Gulf or prescribed SST in simulating the regional atmospheric climate; neither of these two approaches is suitable for addressing the above question or for projecting the future climate in this region. For the first time, a high-resolution, two-way, coupled Gulf-atmosphere regional model (GARM) is developed, forced by solar radiation and constrained by observed lateral boundary conditions, suited for the study of current and future climates of the Persian Gulf. Here, this study demonstrates the unique capability of this model in consistently predicting surface heat and water fluxes and lateral heat and water exchanges with the Arabian Sea, as well as the variability of water temperature and water mass. Although these variables are strongly coupled, only SST has been directly and sufficiently observed. The coupled model succeeds in simulating the water and heat budgets of the Persian Gulf without any artificial flux adjustment, as demonstrated in the close agreement of model simulation with satellite and in situ observations.The coupled regional climate model simulates a net surface heat flux of 13 W m 22 , suggesting a small net heat flux from the atmosphere into the Persian Gulf. The annual evaporation from the Persian Gulf is 1.84 m yr 21 , and the annual influx and outflux of water through the Strait of Hormuz between the Persian Gulf and Arabian Sea are equivalent to Persian Gulf-averaged precipitation and evaporation rates of 33.7 and 32.1 m yr 21 , with a net influx of water equivalent to a Persian Gulf-averaged precipitation rate of 1.6 m yr 21. The average depth of the Persian Gulf water is ;38 m. Hence, it suggests that the mean residency time scale for the entire Persian Gulf is ;14 months.

Modulation of Winter Precipitation Dynamics Over the Arabian Gulf by ENSO

“…Identifying the sources of moisture and the mechanism of the development of atmospheric instability is vital in understanding the dynamics of the precipitating weather systems. The model‐based estimates of the Arabian Gulf water budget suggest that the Gulf receives more precipitation than the local evaporation, indicating the importance of moisture transport from elsewhere (Xue & Eltahir, ). The lagged composites of moisture transport vectors in Figure illustrates that the moisture transport is from the Arabian and Red Seas during heavy precipitation events.…”

“…The few winter precipitation events received over this region are important for the society and ecology of the region. Also, the Gulf is a shallow sea with an average depth of about 37 m (Xue & Eltahir, ) and the precipitation received is important to maintain the heat and salinity budgets and thereby the ecology of the Gulf itself. Despite its importance, there were not many studies that focus on the dynamics of the Arabian Gulf rainfall.…”

“…The region is already water stressed, and the desalinated water from the Arabian Gulf is extensively used to support the population in the surrounding cities that causes further environmental stress on the water body (Sheppard et al, ). Despite its importance, the mechanisms of precipitation over the Arabian Gulf are not explored in detail, primarily due to scarcity of observations (Xue & Eltahir, ). It is essential to understand the mechanisms of precipitation and its variability over this region to make robust assessments of water stress that the Gulf undergoes in a warming climate, especially in the wake of projections of a decreased storm track activity and changes in spatial pattern of simulated precipitation over the region (Evans, , ).…”

Host adaptation and unexpected symbiont partners enable reef‐building corals to tolerate extreme temperatures

“…Summers in the southern Gulf are ~1°C warmer than eastern and northwestern sites where D1a associations have been documented, and while cold winters and high salinity also characterize the southern Gulf, these are only more extreme that the northwestern sites (http://www.seatemperature.org, Yao & Johns, ; see also Hume et al ., for discussion). Alternatively, restricted dispersal of D1a may overlay environmental factors and reduce the opportunities for southern Gulf hosts to uptake D1a genotypes during symbiosis establishment (Xue & Eltahir, ). Instead, P. daedalea corals from the southern Gulf host symbionts belonging to Symbiodinium C3 which are known elsewhere for their heat sensitivity (e.g., Jones et al ., ).…”

An investigation of the thermal response to meteorological forcing in a hydrodynamic model of Lake Superior

“…Furthermore, the temporal and spatial variability of surface heat flux that is calculated dynamically reflects the real-time lakeair feedback processes. Previous studies have shown that models can suffer systematic bias in SST simulation in regional seas (even though the mean state of surface heat flux was correctly specified) if the highfrequency variability of the surface heat flux does not match the response time scale of local air-sea feedbacks [Xue and Eltahir, 2015]. Although our model configuration is not able to fully resolve the lake-air interactions (e.g., the lake-air interactions in response to the perturbation of surface water temperature also affect the low-level cloud coverage and wind fields, which consequently affect the incoming solar radiation, and latent and sensible heat fluxes), the analyses help to explain the dynamical reasons why the model produces a better simulation when driven with dynamically computed surface heat fluxes than when driven by the precomputed surface heat flux.…”