Intercomparison of hydrologic processes in AMIP GCMs
- NASA/Goddard Space Flight Center, Greenbelt, MD (United States)
Results of an intercomparison study under the Atmospheric Model Intercomparison Project (AMIP) to assess the abilities of 29 global climate models (GCMs) in simulating various aspects of regional and hydrologic processes in response to observed sea surface temperature and sea ice boundary forcings are presented. The authors find that the models generally portray an earthlike climate to approximately 10%-20% of the global land surface temperature (= 14.8{degrees}C) and global precipitation (= 2.3 mm day{sup -1}). While a majority of the models have a reasonable global water budget, about a quarter of the models show significant errors in the total global water balance. While the model frequency distributions of heavy precipitation associated with deep convection are in reasonable agreement with observations, a systematic underestimate of the frequency of occurrence of light precipitation events is present in almost all the AMIP models, especially over continental desert regions and over tropical and subtropical oceanic regions contiguous to the west coasts of continents where low-level stratocumulus clouds tend to occur. Another common problem in the global rainfall distribution is the presence of spectral rain or spurious gridpoint-scale heavy rain. On the interannual timescale, the models show reasonable skills in simulating the fluctuations of the Southern Oscillation and the eastward migration of the major equatorial precipitation zone during ENSO. Overall, the models depict a reasonably realistic annual cycle of water balance over regions where long-term local moisture balance is maintained. These results suggest that while some GCMs may have moderate capability in capturing some aspects of the climatological variation of runoff, it is premature to use them for climate studies related to continental-scale water balance. A ranking of the AMIP models and some possibilities implications based on the above performance are also presented. 23 refs., 13 figs., 3 tabs.
- OSTI ID:
- 513347
- Journal Information:
- Bulletin of the American Meteorological Society, Journal Name: Bulletin of the American Meteorological Society Journal Issue: 10 Vol. 77; ISSN 0003-0007; ISSN BAMIAT
- Country of Publication:
- United States
- Language:
- English
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