Article Type:
Research Article

Removal of Distortion Error from an Ensemble Forecast

Jun Du Institute of Atmospheric Physics, The University of Arizona, Tucson, Arizona

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Steven L. Mullen Institute of Atmospheric Physics, The University of Arizona, Tucson, Arizona

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Frederick Sanders Marblehead, Massachusetts

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Print Publication:
01 Sep 2000
DOI:
https://doi.org/10.1175/1520-0493(2000)128<3347:RODEFA>2.0.CO;2
Page(s):
3347–3351
Restricted access

Abstract

Large errors developed by 24 h during a 25-member ensemble forecast of quantity of precipitation. The errors could be attributed to an insufficient northeastward motion of the area of precipitation and excessive amounts. This was determined by partitioning of the root-mean-square error into a distortion error, the sum of contributions from incorrect position and magnitude, and a residual error. The distortion error accounted for more than half of the total error. The distortion error occurs on the synoptic scale and can likely be somewhat ameliorated by future improvements in analysis–forecast systems. The residual error occurs at smaller, less predictable scales, and prospects for its deterministic improvement are not so sanguine.

* Current affiliation: National Centers for Environmental Prediction, Washington, D.C.

Corresponding author address: Dr. Steven L. Mullen, Department of Atmospheric Sciences, The University of Arizona, 1118 E. 4th Street, Tucson, AZ 85721.

Email: atmosci@atmo.arizona.edu

Abstract

Large errors developed by 24 h during a 25-member ensemble forecast of quantity of precipitation. The errors could be attributed to an insufficient northeastward motion of the area of precipitation and excessive amounts. This was determined by partitioning of the root-mean-square error into a distortion error, the sum of contributions from incorrect position and magnitude, and a residual error. The distortion error accounted for more than half of the total error. The distortion error occurs on the synoptic scale and can likely be somewhat ameliorated by future improvements in analysis–forecast systems. The residual error occurs at smaller, less predictable scales, and prospects for its deterministic improvement are not so sanguine.

* Current affiliation: National Centers for Environmental Prediction, Washington, D.C.

Corresponding author address: Dr. Steven L. Mullen, Department of Atmospheric Sciences, The University of Arizona, 1118 E. 4th Street, Tucson, AZ 85721.

Email: atmosci@atmo.arizona.edu

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