Modeling and Analysis of Snowpack over the Western United States

Jiming Jin

Departments of Watershed Sciences and Plants, Soils, and Climate

Trends of Snow Depth over the Western U.S. (1951-1997)

Mount Hood, Oregon

Barnett et al., 2008

Computerized projections of western United States snowfall levels in 2050 compared to present day

Cannon et al., 2006

Computerized snow-water amounts between now (top) and the century's end (bottom)

The Pacific/North America Pattern (Positive)

PNA = 0.25[Z (20 oN, 160 oW) -Z(45 oN, 165 oW) + Z(55 oN, 115 oW) –Z(30 oN, 85 oW)]

The Pacific/North America Pattern (negative)

PNA = 0.25[Z (20 oN, 160 oW) -Z(45 oN, 165 oW) + Z(55 oN, 115 oW) –Z(30 oN, 85 oW)]

Snow Anomalies Over the western U.S.

EOF = Empirical Orthogonal Functions

Precipitation and Temperature Anomalies Over the western U.S.

500 mb Geopotential Height Anomalies

Precipitation and Temperature Anomalies Over the western U.S.

500 mb Geopotential Height Anomalies

Snotel Stations Over the Sierra Nevada

Snow Simulations from a Regional Climate Model

The Fifth Generation Mesoscale Model (MM5)/ Noah Land Surface Model

Temperature Simulations from a Regional Climate Model

Precipitation Simulations from a Regional Climate Model

Snow Depth simulations from the Weather Research Forecasting (WRF) Model for the Columbia River Basin

Summary

1) The snowpack in the western U.S. is significantly affected by global warming.

2) The interanuual variability of the atmosphere is closely correlated with the snow depth in the western U.S.

3) Our improved version of a regional climate model can realistically simulate the snow depth, and this model can be further used to predict the amount of snow mass.