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Article
An Evaluation of QPF from the WRF, NAM, and GFS Models Using Multiple Verification Methods over a Small Domain
Weather and Forecasting
  • Haifan Yan, Iowa State University
  • William A. Gallus, Jr., Iowa State University
Document Type
Article
Publication Version
Published Version
Publication Date
8-1-2016
DOI
10.1175/WAF-D-16-0020.1
Abstract

The ARW model was run over a small domain centered on Iowa for 9 months with 4-km grid spacing to better understand the limits of predictability of short-term (12 h) quantitative precipitation forecasts (QPFs) that might be used in hydrology models. Radar data assimilation was performed to reduce spinup problems. Three grid-to-grid verification methods, as well as two spatial techniques, neighborhood and object based, were used to compare the QPFs from the high-resolution runs with coarser operational GFS and NAM QPFs to verify QPFs for various precipitation accumulation intervals and on two grid configurations with different resolutions. In general, NAM had the worst performance not only for model skill but also for spatial feature attributes as a result of the existence of large dry bias and location errors. The finer resolution of NAM did not offer any advantage in predicting small-scale storms compared to the coarser GFS. WRF had a large advantage for high precipitation thresholds. A greater improvement in skill was noted when the accumulation time interval was increased, compared to an increase in the spatial neighborhood size. At the same neighborhood scale, the high-resolution WRF Model was less influenced by the grid on which the verification was done than the other two models. All models had the highest skill from midnight to early morning, because the least wet bias, location, and coverage errors were present then. The lowest skill was shown from late morning through afternoon. The main cause of poor skill during this period was large displacement errors.

Comments

This article is published as Yan, Haifan, and William A. Gallus Jr. "An evaluation of QPF from the WRF, NAM, and GFS models using multiple verification methods over a small domain." Weather and Forecasting 31, no. 4 (2016): 1363-1379. DOI: 10.1175/WAF-D-16-0020.1. Posted with permission.

Copyright Owner
American Meteorological Society
Language
en
File Format
application/pdf
Citation Information
Haifan Yan and William A. Gallus. "An Evaluation of QPF from the WRF, NAM, and GFS Models Using Multiple Verification Methods over a Small Domain" Weather and Forecasting Vol. 31 Iss. 4 (2016) p. 1363 - 1379
Available at: http://works.bepress.com/william_gallus/68/