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A New Regional Model for Simulating African Hydroclimate

Paper Reviewed
Moufouma-Okia, W. and Jones, R. 2015. Resolution dependence in simulating the African hydroclimate with the HadGEM3-RA regional climate model. Climate Dynamics 44: 609-632.

Moufouma-Okia and Jones (2015) introduce their work by writing their study documents "the effect of horizontal resolution on the ability of the Met Office third-generation Global Atmosphere Regional Climate Model (HadGEM3-RA)" -- a regional atmospheric configuration of the HadGEM3 model -- "to simulate rainfall variability over Africa," based on "six 20-year-long RCM simulations driven by ERA-Interim reanalysis and performed at 12, 25, 50, 70, 90 and 150 km over the CORDEX-Africa domain."

With respect to the relevant findings derived from this exercise, the two researchers report that (1) "in Central Equatorial Africa, HadGEM3-RA indicates excessive wet biases," as well as (2) "large root-mean square errors." The model also (3) "exaggerates rainfall maxima around the Darfur highlands," (4) "underestimates the maximum of precipitation over the West African monsoon region," produces (5) "a weaker simulated meridional transport of moisture inland during the West Africa Monsoon," and that (6) "this situation worsens with increasing the model horizontal resolution," which ultimately (7) "leads to reduction of seasonal rainfall total in West Africa."

On the bright side of things -- if one can call it that -- Moufouma-Okia and Jones write in the concluding paragraph of their paper that their study "provides insights on the challenges surrounding modelling of the climate variations across Africa and exemplifies the potential of HadGEM3-RA for investigating the local scale drivers of climate model errors in this region," as well as "the need for high resolution datasets for model validation and improved understanding of the physical processes that govern climate variability in Africa." Such remarks sound like yet another example of a worthy enterprise that is ever learning ... but never quite getting to where it needs to go.

Posted 2 June 2015