Evaluating the Utah Energy Balance (UEB) snow model in the Noah land-surface model

摘要

Noah (version 2.7.1), the community land-surface model (LSM) of NationalCenters for Environmental Predictions-National Center for AtmosphericResearch (NCEP-NCAR), which is widely used to describe the land-surfaceprocesses either in stand-alone or in coupled land-atmospheric modelsystems, is recognized to underestimate snow–water equivalent (SWE). Noah'sSWE bias can be attributed to its simple snow sub-model, which does noteffectively describe the physical processes during snow accumulation andmelt period. To improve SWE simulation in the Noah LSM, the Utah EnergyBalance (UEB) snow model is implemented in Noah to test alternatesnow surface temperature and snowmelt outflow schemes. Snow surfacetemperature was estimated using the force-restore method and snowmelt event isregulated by accounting for the internal energy of the snowpack. Themodified Noah's SWE simulations are compared with the SWE observed atCalifornia's NRCS SNOTEL stations for 7 water years: 2002–2008, whilethe model's snow surface temperature is verified with observed surface-temperaturedata at an observation site in Utah. The experiments show thatmodification in Noah's snow process substantially reduced SWE estimationbias while keeping the simplicity of the Noah LSM. The results suggest thatthe model did not benefit from the alternate temperature representation butprimary improvement can be attributed to the substituted snowmelt process.