Noah Land Surface Model modifications to improve snowpack prediction in the Colorado Rocky Mountains

To mitigate these deficiencies, five model modifications are tested to improve snowpack performance: (1) time-varying snow albedo, (2) solar radiation adjustment for terrain slope and orientation, (3) reducing the surface exchange coefficient for stable boundary layers, (4) increase of fresh snow albedo, and (5) adjusting surface roughness length when snow is present.

The Noah LSM is executed from 1 November 2007 to 1 August 2008 for the headwater region in the Colorado Rocky Mountains with complex terrain, and its results are evaluated against 1 km Snow Data Assimilation System (SNODAS) output and individual Natural Resources Conservation Service Snowpack Telemetry (SNOTEL) sites. The most effective way to improve magnitude and timing of seasonal maximum snow water equivalent (SWE) is the introduction of the time-varying albedo formulation and the increase in fresh snow albedo.