The spatial extent and organization of extreme storm events has important practical
implications for flood forecasting. Recently, conflicting evidence has been found on the observed changes
of storm spatial extent with increasing temperatures. To further investigate this question, a regional climate
model assessment is presented for the Greater Sydney region, in Australia. Two regional climate models were
considered: the first a convection-resolving simulation at 2-km resolution, the second a resolution of 10 km
with three different convection parameterizations. Both the 2- and the 10-km resolutions that used the
Betts-Miller-Janjic convective scheme simulate decreasing storm spatial extent with increasing temperatures
for 1-hr duration precipitation events, consistent with the observation-based study in Australia. However,
other observed relationships of extreme rainfall with increasing temperature were not well represented by
the models. Improved methods for considering storm organization are required to better understand
potential future changes.
Figure 3. Scaling of the effective radius with temperature for 1-hr storms.
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Last updated 23 January 2018