Editing IPCC:AR6/WGI/Chapter-Atlas (section)

=== Atlas.10.3 Assessment of Model Performance ===

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An assessment of model performance for the Caribbean region is contained in [[#Atlas.7.1|Atlas.7.1]] on Central America. In summary, the ability of climate models to simulate the climate over the region has improved in many key respects with the application of increased model resolution and a better representation of the land surface processes of particular importance in these advances ( ''high confidence'' ) ''.'' Regional climate models (RCMs) simulate realistically seasonal surface temperature and precipitation patterns including the bimodal rainfall in the precipitation annual cycle although with some timing biases in some regions ( ''high confidence'' ). The important regional circulation and precipitation features, the Caribbean low-level jet and the midsummer drought (MSD), are well represented over a variety of RCM domains covering the region ( ''high confidence'' ).

Over the tropical Pacific, surface temperature biases in CMIP6 models remain similar to those in CMIP5, although are reduced in the higher-resolution models in the HiResMIP ensemble. CMIP6 models generally represent trends in sea surface temperatures better than CMIP5 (see [[IPCC:Wg1:Chapter:Chapter-9#9.2|Section 9.2.1]] for more details). For precipitation, the persistent tropical Pacific bias of the double ITCZ (erroneous bands of excessive rainfall both sides of the equatorial Pacific) is still present in CMIP6 models although is slightly improved compared to those in CMIP3 and CMIP5 models ( [[IPCC:Wg1:Chapter:Chapter-3#3.3.2.3|Section 3.3.2.3]] ). Application of downscaling techniques (RCMs and stretched-grid GCMs) using resolutions finer than 10 km over the Pacific can capture topographic influences on wind and rainfall to generate realistic simulations of island climates – for example over Fiji and New Caledonia ( [[#Chattopadhyay--2015|Chattopadhyay and Katzfey, 2015]] ; [[#Dutheil--2019|Dutheil et al., 2019]] ). In both cases applying bias adjustment to the sea surface temperatures used as a lower boundary condition for the downscaling models was important to generate realistic simulations.

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