Climate Processes in CMIP5 models: Tropical cyclones and environmental variables

Tropical cyclone-like storms were detected and tracked in 14 CMIP5 models using the Camargo-Zebiak algorithm (Camargo and Zebiak, 2002) for historical and future scenarios (Camargo, 2013). We also analyzed in these models various large-scale environmental variables associated with tropical cyclones, such as potential intensity, vertical wind shear, sea surface temperature, and a genesis index. Here we look in more detail in the relationship of TC activity with these and other large-scale variables. Using scatter plots and Taylor diagrams, we analyze the relationship of the number of tropical cyclones with various environmental variables globally and per basin. We also consider the role of model resolution in these relationships. In the case of the CMIP3 models (Walsh et al., 2013), there is a clear relationship between model resolution and tropical cyclone formation rate, even after using resolution-dependent thresholds. We will determine if that is also true for the CMIP5 models. There is little correlation between model genesis index and model storm frequency for low-resolution models, which improves with model resolution (Camargo et al. 2007; Walsh et al. 2013). We will examine if this stronger relationship of genesis index and model TC frequency with resolution also occurs in the CMIP5 model and if it is dependent on which genesis index is used.

References:

Camargo, S.J., 2013. Global and regional aspects of tropical cyclone activity in the CMIP5 models. J. Climate, in review. Camargo, S. J., and S. E. Zebiak, 2002: Improving the detection and tracking of tropical cyclones in atmospheric general circulation models. Wea. Forecasting, 17, 1152-1162. Camargo, S. J., A. H. Sobel, A. G. Barnston, and K. A. Emanuel, 2007: Tropical cyclone genesis potential index in climate models. Tellus, 59A, 428-443. Walsh, K., S. Lavender, E. Scoccimarro, and H. Murakami, 2013: Resolution dependence of tropical cyclone formation in CMIP3 and finer resolution models. Clim. Dyn., 40, 585-599.