Ocean-atmosphere interactions over sub-tropical pacific have important implications with regards to flooding and precipitation patterns in the Western U.S. This research project documents the importance of these ocean-atmosphere processes with regards to snow accumulation and water supply.
CWEST Participants: Noah Molotch, Bin Guan of JPL
Atmospheric RiversAtmospheric Rivers (AR) are narrow regions within the atmosphere that are responsible for most horizontal transport of water vapor outside of the tropics. While AR can create extreme rainfall and floods, they importantly contribute about 40% of total season snow accumulations in the Sierra Nevada Mountains. Small changes in surface air temperature can shift these large, snowpack-generated storms to rain-dominated, flood-producing storms. Additionally, it has been shown that specific phases of the Madden-Julian Oscillation (i.e. atmospheric waves which traverse the Pacific Ocean) favor intense snowfall in the Sierra Nevada . While these works identified the importance of persistent atmospheric circulation patterns with respect to snow accumulations, it did not link atmospheric processes to the intensity of specific storm event. To address this storm-specific gap in knowledge, Molotch 2013 in Water Resources Research, directly linked large-scale modes of atmospheric circulation to the intensity of individual storm events during the record-setting snowfall season of 2011. While this area of research is relatively new, much progress will be made in the context of intense precipitation in the Rocky Mountains.
For more information, please visit NOAA’s Atmospheric River webpage.