Authors
Jeremy Barroll (CIRES), Ben Livneh (CIRES)

Abstract

This study aims to investigate how the relationship between remotely-sensed sea surface temperature (SST) and snow-water equivalent depth (SWE) data varies on a kilometer-scale resolution within small watersheds in high elevation locations in select regions of the Western United States, including the Rocky Mountains in Colorado and the Sierra Nevada in California. We would like to relate this variation to elevation, location relative to prominent crests and latitude/longitude within the larger region. We will also consider long-term shifts in the locations of prediction regions, areas of the oceans where SST anomaly is highly predictive of SWE at a given land location, as well as shifts in the correlative strength of these prediction regions. We have used the study period of water years 1985 through 2021 as this is the temporal range of the satellite-derived high resolution SWE data, and have considered SST data for the North Pacific and North Atlantic Oceans. By grouping the SWE data by watershed and elevation band, we can see which prediction regions have the strongest and most temporally consistent predictive skill. We have found that generally speaking, for the Colorado Rocky Mountains the North Atlantic teleconnections vary more across prominent East-West running divides while the North Pacific teleconnections vary more across prominent North-South running divides. Additionally, the SST data tends to have the highest predictive skill for SWE at high elevations from 400-800 meters below the crest of a given range on either side. We believe this is because correlative strength increases with elevation, however areas along prominent crests receive a mixed atmospheric moisture signal from either side. For example, in the 3200-3600 meter band of the Tomichi Creek Watershed in the Colorado Rocky Mountains (just below and to the west of the Continental Divide), we found that the average of positively correlated locations minus the average of negatively correlated locations in the North Temperate Pacific Ocean correlates with April 1 SWE with an R2 of 0.26.