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A Method to Account for QPF Spatial Displacement Errors in Short-Term Ensemble Streamflow Forecasting
Water
  • Bradley Carlberg, Iowa State University
  • Kristie J. Franz, Iowa State University
  • William A. Gallus, Jr., Iowa State University
Document Type
Article
Publication Version
Published Version
Publication Date
12-13-2020
DOI
10.3390/w12123505
Abstract

To account for spatial displacement errors common in quantitative precipitation forecasts (QPFs), a method using systematic shifting of QPF fields was tested to create ensemble streamflow forecasts. While previous studies addressed spatial displacement using neighborhood approaches, shifting of QPF accounts for those errors while maintaining the structure of predicted systems, a feature important in hydrologic forecasts. QPFs from the nine-member High-Resolution Rapid Refresh Ensemble were analyzed for 46 forecasts from 6 cases covering 17 basins within the National Weather Service North Central River Forecast Center forecasting region. Shifts of 55.5 and 111 km were made in the four cardinal and intermediate directions, increasing the ensemble size to 81 members. These members were input into a distributed hydrologic model to create an ensemble streamflow prediction. Overall, the ensemble using the shifted QPFs had an improved frequency of non-exceedance and probability of detection, and thus better predicted flood occurrence. However, false alarm ratio did not improve, likely because shifting multiple QPF ensembles increases the potential to place heavy precipitation in a basin where none actually occurred. A weighting scheme based on a climatology of displacements was tested, improving overall performance slightly compared to the approach using non-weighted members.

Comments

This article is published as Carlberg, Bradley, Kristie Franz, and William Gallus. "A Method to Account for QPF Spatial Displacement Errors in Short-Term Ensemble Streamflow Forecasting." Water 12, no. 12 (2020): 3505. DOI: 10.3390/w12123505. Posted with permission.

Creative Commons License
Creative Commons Attribution 4.0 International
Copyright Owner
The Author(s)
Language
en
File Format
application/pdf
Citation Information
Bradley Carlberg, Kristie J. Franz and William A. Gallus. "A Method to Account for QPF Spatial Displacement Errors in Short-Term Ensemble Streamflow Forecasting" Water Vol. 12 Iss. 12 (2020) p. 3505
Available at: http://works.bepress.com/william_gallus/83/