CMIP5 rainfall projections
Can we constrain CMIP5 rainfall projections in the tropical Pacific based on their sea surface warming patterns?
Abstract
Climate warming has large implications for rainfall patterns, and identifying the most plausible pattern of rainfall change over the next century among various model projections would be valuable for future planning. The spatial pattern of projected sea surface temperature change has a key influence on rainfall changes in the tropical Pacific. Here we show that simple indices of the size of the equatorial peak in warming and to a lesser extent the hemispheric asymmetry in warming are useful for classifying the sea surface temperature change in different CMIP5 models. The inter-model spread in enhanced equatorial warming is closely related to the rainfall change including the degree of ‘warmer get wetter’ response, and provides a useful framework for constraining projections. Models with a strong equatorial warming show fairly distinct rainfall change pattern from those with a more uniform warming. While there is not a simple emergent constraint for enhanced equatorial warming in models in terms of past trends or bias in the current climate, further understanding of the various feedbacks involved in this one feature could lead to a useful constraint of rainfall across the Pacific and the Pacific Rim.