A comparison of the regional Arctic System Reanalysis and the global ERA- Interim Reanalysis for the Arctic

• Main Authors: David H. Bromwich, Aaron B. Wilson, Le-sheng Bai, George W. K. Moore, Peter
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2015
• Subjects: Arctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.670.8669; http://polarmet.osu.edu/PMG_publications/bromwich_wilson_qjrms_2015.pdf

The Arctic System Reanalysis version 1 (ASRv1), a high-resolution regional assimilation of model output, observations, and satellite data across the mid- and high latitudes of the Northern Hemisphere, and the global European Centre for Medium Range Forecasting Interim Reanalysis (ERAI) are compared to atmospheric observations for the period December 2006 – November 2007. Results throughout the troposphere show observations to be well assimilated in ASRv1, as monthly and annual near-surface (upper-level) temperature, dew point (relative humidity), pressure (geopotential height), and wind speed biases compared to surface stations and radiosondes are very small. These results are similar to ERAI, though wind speed biases are significantly smaller in ASRv1. Despite ASRv1’s use of a 3D-variational (Var) assimilation compared to ERAI’s 4D-Var, similar results suggest that a regional approach with higher-resolution terrain and a detailed land surface description forced by a global reanalysis may improve the assimilation of observations and help offset temporal information lost by 3D-Var compared to 4D-Var. However, ASRv1 forecast field results compared to ERAI are mixed. ASRv1 and ERAI show negative precipitation biases during cool months compared to gauge