Impact of Dynamic Downscaling on the Simulation of Tropical Easterly Waves in the Intra‐Americas Seas

We analyze two 16‐year dynamically downscaled simulations for their Tropical Easterly Waves (TEWs) from global reanalysis of the atmosphere and ocean over the Intra‐Americas Seas (IAS) region, centered over Central America. We implemented two versions of a coupled ocean‐atmosphere Regional Climate Model (RCM), each run at 15 km grid resolution and differing solely in their cumulus parameterization schemes. Our analysis reveals that the RCMs were able to generate TEWs in the domain even though the global atmospheric reanalysis forcing the regional models generated a few TEWs. This seems to suggest an in situ generation of these TEWs in the domain, which is consistent with earlier studies that examined TEW over the IAS region. There were also crucial differences between the two versions of the RCMs, suggesting that the cumulus parameterization scheme has an important bearing on the generation of TEWs in the simulation over this region. In one instance of the RCM simulation, the response of the TEW was much stronger, where the convective activity was enhanced with both convective and stratiform precipitation associated with TEW higher than the other cumulus scheme used in the other RCM simulation. However, the limitations and advantages of the impacts of the two cumulus parameterization schemes on the overall simulation of TEWs refrain us from claiming one scheme is superior to the other. Nonetheless, the study highlights the importance of the cumulus scheme and the benefit of dynamic downscaling on the simulation of TEWs.