Further Evaluation of Probabilistic Convective Precipitation Forecasts Using the QPF–PoP Neighborhood Relationship

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2017-08-01
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Kochasic, Michael
Schaffer, Christopher
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Gallus, William
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Geological and Atmospheric Sciences

The Department of Geological and Atmospheric Sciences offers majors in three areas: Geology (traditional, environmental, or hydrogeology, for work as a surveyor or in mineral exploration), Meteorology (studies in global atmosphere, weather technology, and modeling for work as a meteorologist), and Earth Sciences (interdisciplinary mixture of geology, meteorology, and other natural sciences, with option of teacher-licensure).

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The Department of Geology and Mining was founded in 1898. In 1902 its name changed to the Department of Geology. In 1965 its name changed to the Department of Earth Science. In 1977 its name changed to the Department of Earth Sciences. In 1989 its name changed to the Department of Geological and Atmospheric Sciences.

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1898-present

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  • Department of Geology and Mining (1898-1902)
  • Department of Geology (1902-1965)
  • Department of Earth Science (1965-1977)
  • Department of Earth Sciences (1977-1989)

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A neighborhood postprocessing approach that relates quantitative precipitation forecasts (QPF) to probability of precipitation (PoP) forecasts applied to a single model run was found by Schaffer et al. to be as good as traditional ensemble-based approaches using 10 members in 30-h forecasts of convective precipitation. The present study evaluates if PoP forecasts derived from additional variations of the approach can improve PoP forecasts further compared with previous methods. Ensemble forecasts from the Center for Analysis and Prediction of Storms (CAPS) are used for neighborhood tests comparing a single model run and a traditional ensemble. In the first test, PoP forecasts for different combinations of training and testing datasets using a single model member with 4-km grid spacing are compared against those obtained with a 10-member traditional ensemble. Overall, forecasts for the neighborhood approach with just one member are only slightly less accurate to those using a more traditional neighborhood approach with the ensemble. PoP forecasts improve when using older data for training and newer data for testing. Assessments of the sensitivity of the neighborhood PoPs suggest that thinning of the horizontal grid at fine grid spacing is an effective way of maintaining the accuracy of PoP forecasts while reducing computational expenses. In an additional test, the diurnal variation of the forecast is examined on a day-by-day basis, showing good agreement between the two approaches for all but a few cases during 2008.

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This article is published as Kochasic, Michael C., William A. Gallus Jr, and Christopher J. Schaffer. "Further Evaluation of Probabilistic Convective Precipitation Forecasts Using the QPF-PoP Neighborhood Relationship." Weather and Forecasting 32, no. 4 (2017): 1423-1440. DOI: 10.1175/WAF-D-16-0227.1. Posted with permission.

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Sun Jan 01 00:00:00 UTC 2017
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