Realism of rainfall in a very high-resolution regional climate model

Kendon, E. J., Roberts, N. M., Senior, C. A. and Roberts, M. J. (2012) Realism of rainfall in a very high-resolution regional climate model. Journal of Climate, 25 (17). pp. 5791-5806. ISSN 1520-0442 doi: 10.1175/JCLI-D-11-00562.1

Abstract/Summary

The realistic representation of rainfall on the local scale in climate models remains a key challenge. Realism encompasses the full spatial and temporal structure of rainfall, and is a key indicator of model skill in representing the underlying processes. In particular, if rainfall is more realistic in a climate model, there is greater confidence in its projections of future change. In this study, the realism of rainfall in a very high-resolution (1.5 km) regional climate model (RCM) is compared to a coarser-resolution 12-km RCM. This is the first time a convection-permitting model has been run for an extended period (1989–2008) over a region of the United Kingdom, allowing the characteristics of rainfall to be evaluated in a climatological sense. In particular, the duration and spatial extent of hourly rainfall across the southern United Kingdom is examined, with a key focus on heavy rainfall. Rainfall in the 1.5-km RCM is found to be much more realistic than in the 12-km RCM. In the 12-km RCM, heavy rain events are not heavy enough, and tend to be too persistent and widespread. While the 1.5-km model does have a tendency for heavy rain to be too intense, it still gives a much better representation of its duration and spatial extent. Long-standing problems in climate models, such as the tendency for too much persistent light rain and errors in the diurnal cycle, are also considerably reduced in the 1.5-km RCM. Biases in the 12-km RCM appear to be linked to deficiencies in the representation of convection.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/31222
Identification Number/DOI	10.1175/JCLI-D-11-00562.1
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Publisher	American Meteorological Society
Publisher Statement	© Copyright 2012 of the American Meteorological Society. The AMS Copyright Policy is available on the AMS web site at http://www.ametsoc.org
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