Summary: | In the first part of this work it was determined that general circulation model
(GCM) ECHAM4.5 shows more ability than CCM3.6 to simulate key climate features
of Central America. For such reason, output from ECHAM4.5 was used to perform a
dynamical downscaling experiment using the regional model MM5v3, in which a set
of high-resolution simulations (of up to 30-km horizontal resolution) was generated for
January 2000.
The results of the dynamical downscaling allow to conclude that MM5v3 is able to
suitably reproduce aspects of the Central American climate that GCMs cannot capture
because of their coarse horizontal resolution, their limitations in representing both the
regional topography and the mesoscale dynamical interactions. Comparison with data
derived from observations indicates that the MM5v3 simulates the region of maximum
low-level wind that is related to the Intra-Americas Seas Low Level Jet, although the
regional model underestimates its intensity. Regarding the precipitation patterns, they
agree with those derived from the observations (drier areas in the Pacific, wetter areas
in the Caribbean). Nevertheless, there is a generalized overestimation in the amount
of simulated rain. The analysis of the standard deviation for a twelve-member sample
shows areas in which MM5v3 has greater dispersion or uncertainty (mainly to the
south of Panama).
Keywords: numerical models, seasonal climate prediction, dynamical downscaling, climate,
climate variability.
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