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

2015 ◽  
Vol 28 (13) ◽  
pp. 5041-5062 ◽  
Author(s):  
Pengfei Xue ◽  
Elfatih A. B. Eltahir
Keyword(s):  
Heat Flux ◽  
Regional Climate Model ◽  
Persian Gulf ◽  
Arabian Sea ◽  
Climate Model ◽  
Regional Climate ◽  
Surface Heat ◽  
Surface Fluxes ◽  
Water Budgets ◽  
The Persian Gulf

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 +3 W m−2, 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−1, 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−1, with a net influx of water equivalent to a Persian Gulf–averaged precipitation rate of 1.6 m yr−1. 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.

scholarly journals Introducing an Irrigation Scheme to a Regional Climate Model: A Case Study over West Africa

2014 ◽  
Vol 27 (15) ◽  
pp. 5708-5723 ◽  
Author(s):  
Marc P. Marcella ◽  
Elfatih A. B. Eltahir
Keyword(s):  
Heat Flux ◽  
Land Cover ◽  
West Africa ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Vegetation Model ◽  
Irrigation Scheme ◽  
Dynamic Vegetation Model ◽  
Niger River

Abstract This article presents a new irrigation scheme and biome to the dynamic vegetation model, Integrated Biosphere Simulator (IBIS), coupled to version 3 of the Regional Climate Model (RegCM3-IBIS). The new land cover allows for only the plant functional type (crop) to exist in an irrigated grid cell. Irrigation water (i.e., negative runoff) is applied until the soil root zone reaches relative field capacity. The new scheme allows for irrigation scheduling (i.e., when to apply water) and for the user to determine the crop to be grown. Initial simulations show a large sensitivity of the scheme to soil texture types, how the water is applied, and the climatic conditions over the region. Application of the new scheme is tested over West Africa, specifically Mali and Niger, to simulate the potential irrigation of the Niger River. A realistic representation of irrigation of the Niger River is performed by constraining the land irrigated by the annual flow of the Niger River and the amount of arable land in the region as reported by the Food and Agriculture Organization of the United Nations (FAO). A 30-yr simulation including irrigated cropland is compared to a 30-yr simulation that is identical but with no irrigation of the Niger. Results indicate a significant greening of the irrigated land as evapotranspiration over the crop fields largely increases—mostly via increases in transpiration from plant growth. The increase in the evapotranspiration, or latent heat flux (by 65–150 W m−2), causes a significant decrease in the sensible heat flux while surface temperatures cool on average by nearly 5°C. This cooling is felt downwind, where average daily temperatures outside the irrigation are reduced by 0.5°–1.0°C. Likewise, large increases in 2-m specific humidity are experienced across the irrigated cropland (on the order of 5 g kg−1) but also extend farther north and east, reflecting the prevailing surface southwesterlies. Changes (decreases) in rainfall are found only over the irrigated lands of west Mali. The decrease in rainfall can be explained by the large surface cooling and collapse of the boundary layer (by approximately 500 m). Both lead to a reduction in the triggering of convection as the convective inhibition, or negative buoyant energy, is never breached. Nevertheless, the new scheme and land cover allows for a novel line of research that can accurately reflect the effects of irrigation on climate and the surrounding environment using a dynamic vegetation model coupled to a regional climate model.

scholarly journals Coupling of Integrated Biosphere Simulator to Regional Climate Model Version 3

2009 ◽  
Vol 22 (10) ◽  
pp. 2743-2757 ◽  
Author(s):  
Jonathan M. Winter ◽  
Jeremy S. Pal ◽  
Elfatih A. B. Eltahir
Keyword(s):  
Heat Flux ◽  
Regional Climate Model ◽  
Latent Heat Flux ◽  
Land Surface ◽  
Climate Model ◽  
Regional Climate ◽  
Sensible Heat Flux ◽  
Longwave Radiation ◽  
Sensible Heat ◽  
Integrated Biosphere Simulator

Abstract A description of the coupling of Integrated Biosphere Simulator (IBIS) to Regional Climate Model version 3 (RegCM3) is presented. IBIS introduces several key advantages to RegCM3, most notably vegetation dynamics, the coexistence of multiple plant functional types in the same grid cell, more sophisticated plant phenology, plant competition, explicit modeling of soil/plant biogeochemistry, and additional soil and snow layers. A single subroutine was created that allows RegCM3 to use IBIS for surface physics calculations. A revised initialization scheme was implemented for RegCM3–IBIS, including an IBIS-specific prescription of vegetation and soil properties. To illustrate the relative strengths and weaknesses of RegCM3–IBIS, one 4-yr numerical experiment was completed to assess ability of both RegCM3–IBIS (with static vegetation) and RegCM3 with its native land surface model, Biosphere–Atmosphere Transfer Scheme 1e (RegCM3–BATS1e), to simulate the energy and water budgets. Each model was evaluated using the NASA Surface Radiation Budget, FLUXNET micrometeorological tower observations, and Climate Research Unit Time Series 2.0. RegCM3–IBIS and RegCM3–BATS1e simulate excess shortwave radiation incident and absorbed at the surface, especially during the summer months. RegCM3–IBIS limits evapotranspiration, which allows for the correct estimation of latent heat flux, but increases surface temperature, sensible heat flux, and net longwave radiation. RegCM3–BATS1e better simulates temperature, net longwave radiation, and sensible heat flux, but systematically overestimates latent heat flux. This objective comparison of two different land surface models will help guide future adjustments to surface physics schemes within RegCM3.

Qinghai-Xizang (Tibetan) Plateau climate simulation using the regional climate model RegCM3

2013 ◽  
Vol 57 (3) ◽  
pp. 173-186 ◽  
Author(s):  
X Wang ◽  
M Yang ◽  
G Wan ◽  
X Chen ◽  
G Pang
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Climate Simulation

Evaluation of net shortwave radiation over China with a regional climate model

2020 ◽  
Vol 80 (2) ◽  
pp. 147-163
Author(s):  
X Liu ◽  
Y Kang ◽  
Q Liu ◽  
Z Guo ◽  
Y Chen ◽  
...  
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Radiant Energy ◽  
Energy System ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Monsoon Region ◽  
Clear Sky ◽  
Sky Conditions

The regional climate model RegCM version 4.6, developed by the European Centre for Medium-Range Weather Forecasts Reanalysis, was used to simulate the radiation budget over China. Clouds and the Earth’s Radiant Energy System (CERES) satellite data were utilized to evaluate the simulation results based on 4 radiative components: net shortwave (NSW) radiation at the surface of the earth and top of the atmosphere (TOA) under all-sky and clear-sky conditions. The performance of the model for low-value areas of NSW was superior to that for high-value areas. NSW at the surface and TOA under all-sky conditions was significantly underestimated; the spatial distribution of the bias was negative in the north and positive in the south, bounded by 25°N for the annual and seasonal averaged difference maps. Compared with the all-sky condition, the simulation effect under clear-sky conditions was significantly better, which indicates that the cloud fraction is the key factor affecting the accuracy of the simulation. In particular, the bias of the TOA NSW under the clear-sky condition was <±10 W m-2 in the eastern areas. The performance of the model was better over the eastern monsoon region in winter and autumn for surface NSW under clear-sky conditions, which may be related to different levels of air pollution during each season. Among the 3 areas, the regional average biases overall were largest (negative) over the Qinghai-Tibet alpine region and smallest over the eastern monsoon region.

Sign in / Sign up

Export Citation Format

Share Document