Tuesday, February 12, 2013

New paper predicts a global decrease in cyclones over 21st century

A paper published today in the Journal of Climate predicts "global reduction of tropical cyclones between about 6—20%" over the 21st century. The paper adds to many other peer-reviewed papers demonstrating that global cyclone activity has decreased and is expected to further decline over the 21st century. Thus, the claims of climate alarmists that Sandy or other cyclones have any link to alleged man-made global warming is not supported by the scientific literature.


An assessment of a model-, grid- and basin-independent tropical cyclone detection scheme in selected CMIP3 global climate models

K. J. Tory,1 S. S. ChandR. A. Dare, and J. L. McBride
Centre for Australian Weather and Climate Research, Bureau of Meteorology, Melbourne, Victoria, Australia


Abstract
A novel TC detection technique designed for coarse resolution models is tested and evaluated. The detector, based on the Okubo-Weiss-Zeta parameter (OWZP) is applied to a selection of CMIP3 models (CSIRO-Mk3.5, MPI-ECHAM5, GFDL2.0 and GFDL2.1) and the combined performance of the model and detector is assessed by comparison with observed TC climatology for the period 1970—2000. Preliminary TC frequency projections are made using the three better performing models by comparing the detected TC climatologies between the late 20th and the late 21st centuries. Very reasonable TC formation climatologies were detected in CSIRO-Mk3.5, MPI-ECHAM5 and GFDL2.1 for most basins, with the exception being the North Atlantic where a large under-detection was present in all models. The GFDL2.0 model was excluded from the projection study due to a systematic under-detection in all basins. The above detection problems have been reported in other published studies, which suggests model rather than detector limitations are mostly responsible. This study demonstrates that coarse resolution climate models do in general produce TC-like circulations with realistic geographical and seasonal distributions detectable by the OWZP TC detector. The preliminary projection results are consistent with the published literature, based on higher resolution studies, of a global reduction of TCs [Tropical Cyclones] between about 6—20%, with a much larger spread of results (about +20 to -50%) in individual basins.

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