Wright, David M., Posselt, Derek J., Steiner, Allison
L., University of Michigan
In this study,
high-resolution WRF model simulations are used to explore the sensitivity of
Great Lakes lake-effect snowfall (LES) to changes in lake ice and temperature.
A control simulation with observed ice cover is compared with three sensitivity
tests: complete ice cover, no lake ice, and warmer lake surface temperature.
Complete ice cover is found to eliminate lake effect snowfall, while LES
placement in cases with at least partially unfrozen lake surface is determined
by the location of lake ice. Removal of ice cover results in expansion of the
area affected by LES, while an increase in lake temperature primarily increases
snowfall amount. There is no change in LES morphology for differing lake
surface properties. With increases in lake temperature and removal of lake ice,
water vapor content increases in the boundary layer. The increased water vapor
source leads to higher snowfall intensities, while the topographic features
over land lead to placement of the bands. The results imply that realistic
simulation of the position and occurrence of lake ice cover is essential for
long term simulations of Great Lakes winter precipitation and climate, and that
warmer lakes with reduced ice can increase the spatial extent and magnitude of
LES.