Paper Reviewed

Martin, E.R. and Thorncroft, C. 2015. Representation of African easterly waves in CMIP5 models. Journal of Climate 28: 7702-7715.

Introducing their study of an important aspect of their foray into the intriguing realm of climate modeling, Martin and Thorncroft (2015) begin by noting that "African easterly waves (AEWs) are the dominant synoptic weather systems to impact rainfall across the Sahel during the West African monsoon (WAM)," citing the earlier study of Kiladis et al.(2006), while further noting that they also play "an important role in Atlantic tropical cyclone (TC) development," as demonstrated some time ago by Landsea (1993) and Pasch et al. (1998). So how well do present-day climate models represent climatic features associated with AEWs?

The two U.S. researchers begin by noting that "large biases exist in the simulation of [1] low (850 hPa) and [2] midlevel (700 hPa) eddy kinetic energy in the AMIP [atmospheric model intercomparison project] and historical simulations," as well as (3) "excessive eddy kinetic energy" and (4) "deficient rainfall south of 17°N." They also report that (5) "CMIP5 models are unable to propagate AEWs across the coast and into the Atlantic," and that (6) "large differences exist in future projections between high- and low-resolution models." And they thus conclude that "the simulation of AEWs is challenging for CMIP5 models and must be further diagnosed in order to accurately predict future [7] tropical cyclone activity and [8] rainfall in the Sahel."

References
Kiladis, G.N., Thorncroft, C.D. and Hall, N.M.J. 2006. Three-dimensional structure and dynamics of African easterly waves. Part I: Observations. Journal of the Atmospheric Sciences 63: 2212-2230.

Landsea, C.W. 1993. A climatology of intense (or major) Atlantic hurricanes. Monthly Weather Review 121: 1703-1713.

Pasch, R.J., Avila, L.A. and Jiing, J.-G. 1998. Atlantic tropical systems of 1994 and 1995: A comparison of a quiet season to a near-record-breaking one. Monthly Weather Review 126: 1106-1123.