Remote Impact on Tropical Atlantic Climate Variability: Statistical Assessment and Dynamic Assessment*

Abstract

The remote impact of tropical Pacific and North Atlantic climate forcing on the tropical Atlantic sea surface temperature variability is assessed using both a traditional statistical correlation method and a model-aided dynamic method. Consistently, both assessment methods suggest that the remote impact contributes to nearly half of the variance of the tropical Atlantic sea surface temperature variability at interannual and decadal time scales. In the meantime, the other half of the sea surface temperature variability is generated predominantly in the tropical Atlantic climate system, with local ocean-atmosphere coupling playing a critical role. Furthermore, the leading sea surface temperature variability modes seem also to originate predominantly internally in the tropical Atlantic climate system. The main effect of the remote impact is therefore an enhancement of the variance of these variability modes. This model study also shows some differences between the statistical and dynamic assessment methods, which may have implications on the methodology of the assessment as well as the dynamics of the system.