Snowmelt and
Elevation
menu / contact information / cv / publications / presentations / diurnal cycles in streamflow /
streamflow timing / Yosemite field work / snowmelt and elevation / teaching / coastal fog
Lundquist, J., D. Cayan, and M. Dettinger, 2004. Spring onset in the Sierra Nevada: When is snowmelt independent of elevation? J. Hydromet., 5, 325-340.
Recent studies have shown that
USGS-monitored rivers draining the Sierra Nevada and Rocky Mountains all rise
together each spring, suggesting an organized signal of snowmelt initiation across
the region. These are all large basins
(over 100 km2), spanning similar ranges of aspect and
elevation. However, within a given
basin, should we expect the spring pulse of snowmelt to occur at the same time
in a 470 km2 basin gauged at 1200 m as in a 2 km2 glacial
cirque gauged at 3200 m? Should streamflow from a north-facing cirque rise and peak at the
same time as that from a south-facing cirque?
Data from sub-basins of the
Elevation and aspect exert strong influences on air temperature and solar radiation, but often the influence of synoptic weather systems is stronger. Synchronous snowmelt initiation, so named when 90% of CDWR snow pillows recorded maximum snow accumulation and melt initiation within five days of each other, occurred in four out of eleven springs between 1992 and 2002. These springs are characterized by strong, cold winter storms that persist into March or April. When the storms clear, a rapid temperature rise of over 10°C, combined with dry, easterly winds, marks a clear transition between winter and spring. Other years have a period of little or no storm activity preceding the onset of spring melt, allowing elevation and aspect to play a more dominant role as spring arrives gradually.