Dynamical and Thermodynamic Elements of Modeled Climate Change at the East African Margin of Convection. Issue 2 (23rd January 2018)

• Record Type: Journal Article
• Authors: Giannini, Alessandra; Lyon, Bradfield; Seager, Richard; Vigaud, Nicolas
• Is Part Of: Geophysical research letters. Volume 45:Issue 2(2018)
• Page Start: 992
• Page End: 1000
• Publication Date: 2018-01-23
• Subjects: moisture budget -- climate change -- equatorial East Africa; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2017GL075486
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: We propose a dynamical interpretation of model projections for an end‐of‐century wetting in equatorial East Africa. In the current generation of global climate models, increased atmospheric moisture content associated with warming is not the dominant process explaining the increase in rainfall, as the regional circulation is only weakly convergent even during the rainy seasons. Instead, projected wetter future conditions are generally consistent with the El Niño‐like trend in tropical Pacific sea surface temperatures in climate models. In addition, a weakening in moisture convergence over the adjacent Congo Basin and Maritime Continent cores of convection results in the weakening of near‐surface winds, which increases moisture advection from the Congo Basin core toward the East African margin. Overall confidence in the projections is limited by the significant biases in simulation of the regional climatology and disagreement between observed and modeled tropical Pacific sea surface temperature trends to date. Key Points: Moisture budget decomposition indicates that CMIP5 end of 21st century projections for wetter conditions in equatorial East Africa are primarily due to a weakening of the zonal overturning circulation Uncertainties are associated with our limited understanding of the response of sea surface temperatures, El Niño, and monsoons to warming, as well as the realism of East African orography in the models