Evaluation of gridded snow products using CloudSat snowfall estimates

Abstract:

Arctic snow is a critical contributor to the global water and energy budget with impacts to cold region flooding and water resource management practices. Snow water equivalent (SWE) is the amount of liquid water contained within a snowpack. Measuring Arctic SWE through traditional ground-based techniques is challenging due to the large size and remote nature of the region. Remote sensing applications offer new perspectives towards SWE accumulation estimates across the Arctic through their remote orbit and high repeat cycle. The cloud profiling radar (CPR) installed on the NASA CloudSat satellite observes snapshots of falling snow in clouds and can be used for estimating surface SWE accumulation across high latitudes at monthly timescales. Comparing outliers between two month average SWE accumulation estimates from CloudSat and accumulated SWE on ground estimates over the same two month period in gridded SWE products provides new insights into areas and periods of anomalous accumulation estimates. Applying this technique to terrestrial SWE from the Blended-4 (B4) gridded SWE product from 60 degrees to 90 degrees N at 1 degree resolution, allows us to generate a quality flag grid to further analyze the B4 dataset. This technique identifies 7963 flagged locations and periods from January 2007 to December 2015 as having potentially anomalous accumulation estimates. CPR snowfall estimates provide a new observational constraint towards accumulated SWE measurements in a region which is both difficult and expensive to traditionally observe. The outlier detection method described in this work can be used to further analyze and enhance the accuracy and robustness of future gridded SWE products.