Trends and projections of storm formation in coupled climate models

Abstract

Changes in the characteristics of southern hemisphere storms, in all seasons, during the second half of the twentieth century, were related to changes in the annual cycle of Southern Hemisphere baroclinic instability. In particular, significant negative trends in baroclinic instability were found in a mid-latitude zonal band in all months; a similar band of significant positive trends occurs further poleward. Corresponding to this decrease\ increase in baroclinic instability there was a decrease\increase in storm formation at these latitudes, and in some cases a preference for storm formation further poleward than normal. These changes in the weather systems are consistent with the observed negative trends in southern Australian rainfall. Future projections of trends in baroclinicity, under the RCP8.5 scenario, show a similar pattern of negative and positive trends during the second half of the twenty first century. The impact of these trends is continuing decreased and negative trends in southern Australian rainfall. References

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