Evaluating Model Physics in the Unified Forecast System (UFS) Medium-Range Weather Application Journal Article uri icon

Overview

abstract

  • To support the development of the Global Forecast System (GFS) physics; suite and identify opportunities for improving the model physics in the; UFS, the Developmental Testbed Center (DTC) conducted an array of; analyses for evaluating the operational GFSv15 forecasts and the; experimental forecasts using the GFSv16beta physics suite distributed; with the UFS Medium-Range Weather Application v1.0 public release.; Five-day GFSv16beta forecasts for one boreal winter season were; generated using the operational GFS analyses as initial conditions. The; evaluation metrics included tools from Model Evaluation Tools (MET) and; in-house process-oriented diagnostics. The evaluations focused on the; perpetuating GFS forecast errors pertaining to the planetary boundary; layer (PBL), land-surface, cumulus, radiation, and cloud processes. The; runs using GFSv16beta outperformed the operational GFSv15 with respect; to the root-mean-square errors of large-scale environmental variables; and the anomaly correlation coefficient for 500 hPa geopotential height.; Nevertheless, larger biases associated with key physical processes were; identified in the GFSv16beta forecasts. For example, the global; precipitation forecast skill degrades and a dry bias remains in the; tropics, suggesting a persistent problem in the cumulus scheme. The; near-surface and boundary-layer cold biases are larger over most; continents and polar regions, which is partly related to the systematic; negative temperature errors in the GFS analysis. The overestimated; near-surface wind speed particularly at night in the northeastern U.S.; implies that the surface drag may be underrepresented. Excessive; short-wave radiation reaching the ground in the high-latitudes of the; summer hemisphere appears to be related to low cloud liquid and ice; water path. These and other results will be described in this; presentation.

publication date

  • November 25, 2020

has restriction

  • hybrid

Date in CU Experts

  • July 26, 2021 2:16 AM

Full Author List

  • BERNARDET L; Li W; Harrold M; Sun X; Henderson J; Xue L; D'Amico D; Dudhia J; Ek M

author count

  • 9

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