Evaluation of ERA5-Land and HARv2 Reanalysis Data at High Elevation in the Upper Dudh Koshi Basin (Everest Region, Nepal)

• DOI: 10.1175/jamc-d-21-0091.1
• Publication Date: 2022-06-02T16:23:40Z
• Authors: Arbindra Khadka; Patrick Wagnon; Fanny Brun; Dibas Shrestha; Yves Lejeune; Yves Arnaud
• Keywords: Shortwave; Longwave; Shortwave radiation; Outgoing longwave radiation; Elevation (ballistics)

Abstract We present a multisite evaluation of meteorological variables in the Everest region (Nepal) from ERA5-Land and High Asian Refined Analysis, version 2 (HARv2), reanalyses comparison with situ observations, using classical statistical metrics. Observation data have been collected since 2010 by seven stations located on or off glacier between 4260 6352 m MSL upper Dudh Koshi basin; 2-m air temperature, specific relative humidities, wind speed, incoming shortwave longwave radiations, precipitation are considered successively. Overall, both gridded datasets able to resolve mesoscale atmospheric processes, slightly better performance for HARv2 than that ERA5-Land, especially speed. Because complex topography, they fail reproduce local- microscale processes captured at individual stations, large spatial variability such as Air temperature is variable best reanalyses, long an appropriate elevational gradient above ground, spatiotemporally preferentially assessed local used extrapolate it vertically. A cold bias still observed but attenuated over clean-ice glaciers. The water content well represented even though we observe small humid bias, more important HARv2, spectacular overestimation during monsoon. agreement reanalyzed radiations depends elevation difference station site reanalysis grid cell. seasonality speed only HARv2. two applicable mass energy balance studies, either dynamical downscaling techniques scale mismatch coarse grids fine-scale sites.