Sensitivity of horizontal resolution in the AGCM simulations of Warm season diurnal cycle of precipitation over the United States and Northern Mexico

Myong In Lee, Siegfried D. Schubert, Max J. Suarez, Isaac M. Held, Arun kumar, Thomas L. Bell, Jae Kyung E. Schemm, Ngar Cheung Lau, Jeffrey J. Ploshay, Hyun Kyung Kim, Soo Hyun Yoo

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Abstract

This study examines the sensitivity of the North American warm season diurnal cycle of precipitation to changes in horizontal resolution in three atmospheric general circulation models, with a primary focus on how the parameterized moist processes respond to improved resolution of topography and associated local/regional circulations on the diurnal time scale. It is found that increasing resolution (from approximately 2° to 1/2° in latitude-longitude) has a mixed impact on the simulated diurnal cycle of precipitation. Higher resolution generally improves the initiation and downslope propagation of moist convection over the Rockies and the adjacent Great Plains. The propagating signals, however, do not extend beyond the slope region, thereby likely contributing to a dry bias in the Great Plains. Similar improvements in the propagating signals are also found in the diurnal cycle over the North American monsoon region as the models begin to resolve the Gulf of California and the surrounding steep terrain. In general, the phase of the diurnal cycle of precipitation improves with increasing resolution, though not always monotonically. Nevertheless, large errors in both the phase and amplitude of the diurnal cycle in precipitation remain even at the highest resolution considered here. These errors tend to be associated with unrealistically strong coupling of the convection to the surface heating and suggest that improved simulations of the diurnal cycle of precipitation require further improvements in the parameterizations of moist convection processes.

Original languageEnglish (US)
Pages (from-to)1862-1881
Number of pages20
JournalJournal of Climate
Volume20
Issue number9
DOIs
StatePublished - May 1 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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    Lee, M. I., Schubert, S. D., Suarez, M. J., Held, I. M., kumar, A., Bell, T. L., Schemm, J. K. E., Lau, N. C., Ploshay, J. J., Kim, H. K., & Yoo, S. H. (2007). Sensitivity of horizontal resolution in the AGCM simulations of Warm season diurnal cycle of precipitation over the United States and Northern Mexico. Journal of Climate, 20(9), 1862-1881. https://doi.org/10.1175/JCLI4090.1