AGU: Geophysical Research Letters

 

Editors' Highlight

New model better represents the effect of global climate patterns on the Amazon basin

El Niño–Southern Oscillation (ENSO) cycles strongly influence the interannual variability of climate, weather patterns, and streamflow in South America's Amazon basin. However, current global climate models (GCMs) are unable to exactly capture this variability, in part because the grids used in GCMs (roughly 2°–4° of latitude and longitude) are too large to properly resolve topographical features such as the Andes, which have a narrow width (only 200–300 km). Seeking to correct for this, Medvigy et al. (2008) used the Ocean-Land-Atmosphere Model (OLAM), a new Earth System Model (ESM), which is capable of simulating regions like mountain ranges at selectively high resolution while the remainder of the world continues to be simulated at coarser resolution. They found that when the Andes are resolved more coarsely than 100 km, the model incorrectly simulates ENSO effects such as the dry anomalies that are observed in the Amazon during ENSO events. In contrast, the model correctly simulates the observed dry conditions provided that the Andes are simulated at resolutions finer than 100 km.

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