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Modeling Caribbean Precipitation: How Well Is It Being Done?

Paper Reviewed
Ryu, J.-H. and Hayhoe, K. 2014. Understanding the sources of Caribbean precipitation biases in CMIP3 and CMIP5 simulations. Climate Dynamics 42: 3233-3252.

Ryu and Hayhoe (2014) assessed "the ability of Global Climate Models participating in phases 3 and 5 of the Coupled Model Intercomparison Project (CMIP3 and CMIP5) to simulate observed annual precipitation cycles over the Caribbean," comparing their predictions "to weather station records and gridded observations." In doing so the two U.S. researchers found that "both CMIP3 and CMIP5 models can be grouped into three categories: (1) models that correctly simulate a bimodal distribution with two rainfall maxima in May-June and September-October, punctuated by a mid-summer drought (MSD) in July-August; (2) models that reproduce the MSD and the second precipitation maxima only; and (3) models that simulate only one precipitation maxima, beginning in early summer." And they report that "more models are now able to reproduce the bimodal structure of the annual cycle of Caribbean precipitation in the CMIP5 simulations as compared to CMIP 3." However, they also found that "many of the 'Bimodal' and 'Single with MSD' models from both the CMIP3 and CMIP5 simulations continue to [1] underestimate the magnitude of the early wet season, while [2] over-estimating the second wet season in fall."

In light of these latter findings, Ryu and Hayoe conclude that various hypotheses regarding the origin of the observed biases in the model simulations "remain to be explored in future research," which fact reminds us that we're still not where we need to be when it comes to adequately simulating the annual pattern of Caribbean precipitation.

References
Enfield, D.B. and Alfaro, E.J. 1999. The dependence of Caribbean rainfall on the interaction of the tropical Atlantic and Pacific Oceans. Journal of Climate 12: 2093-2103.

Jury, M.R. 2009. A quasi-decadal cycle in Caribbean climate. Journal of Geophysical Research 114: 10.1029/2009JD011741.

Small, R.J.O., de Szoeke, S.P. and Xie, S.P. 2007. The central American midsummer drought: regional aspects and large-scale forcing. Journal of Climate 20: 4853-4873.

Wang, C. 2007. Variability of the Caribbean low-level jet and its relations to climate. Climate Dynamics 29: 411-422.

Whyte, F., Taylor, M., Stephenson, T. and Campbell, J. 2008. Features of the Caribbean low level jet. International Journal of Climatology 28: 119-128.

Reviewed 24 September 2014