An Analysis of Climate Variability and Snowmelt Mechanisms inMountainous Regions
The impacts of snowpack on climate variability and themechanisms of snowmelt over the Sierra Nevada, California-Nevadamountainous region was studied using the Penn State-National Center forAtmospheric Research fifth-generation Mesoscale Model (MM5) driven by6-hour reanalysis data from the National Centers for EnvironmentalPrediction. The analyses of a one-way nested 48 km to 12 km model runduring the 1998 snowmelt season (April - June) shows that snowpack isunderestimated when there is stronger precipitation and highertemperature. Model resolution and simulated snowpack are found to affectthe temperature and precipitation. Coarser resolution underestimates thetopographic elevation in the Sierra Nevada, increasing the surface airtemperature and precipitation in light of the lapse rate and the rainshadow effect. An observed daily snowpack dataset, assimilated to MM5,reduces the warm bias, because the energy used to increase temperature ina model run without assimilated snow is consumed by snowmelt. The cooledsurface leads to a more stable simulated atmosphere, leading to areduction in the exaggerated precipitation. An underestimated surfacealbedo weakly contributes to the stronger snowmelt. A more realisticphysically-based land-surface model with sophisticated snow andvegetation physics driven by the MM5 output is shown to significantlyimprove the snowpack simulation.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Science; National Aeronautics andSpace Administration
- DOE Contract Number:
- DE-AC02-05CH11231; NASA:#NS-2791
- OSTI ID:
- 918114
- Report Number(s):
- LBNL-53845; R&D Project: G20501; BnR: KP1202020; TRN: US200817%%1129
- Journal Information:
- Journal of Hydrometeorology, Vol. 8, Issue 2; Related Information: Journal Publication Date: 04/2007
- Country of Publication:
- United States
- Language:
- English
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