Oct. 13 Atmospheric Sciences seminar will focus on higher resolution weather forecasts

Jamie Wolff, associate scientist at National Center for Atmospheric Research/Research Applications Laboratory in Boulder, will present a seminar, “Verification methods for assessing NWP models: Pertinent information for the transition to high-resolution forecasts” on Thursday, Oct. 13, at 3 p.m. in 106 Streibel Hall.

Abstract
As computational resources increase, numerical weather prediction  models continue to move toward higher resolution, which, in turn, provide both a finer level of detail and a more realistic structure in the resulting forecast. It is widely acknowledged, however, that using traditional verification metrics for evaluation may unfairly penalize these high resolution forecasts.

Traditional verification requires near-perfect spatial and temporal placement for a forecast to be considered good; this approach favors smoother forecast fields of coarser resolution models and offers no meaningful insight regarding why a forecast is considered good or bad. In contrast, more advanced spatial verification techniques, such as object-based methods, can provide information on differences between forecast and observed objects in terms of displacement, orientation, intensity and coverage areas; neighborhood methods can provide information on the spatial scale at which a forecast becomes skillful.

The Developmental Testbed Center performed an extensive evaluation of the Global Forecast System and the North American Mesoscale operational models to quantify the differences in the performance of Quantitative Precipitation Forecasts produced by two modeling systems that vary significantly in horizontal resolution. Widely used traditional statistics and new, state-of-the art techniques will be described and applied to 3- and 24-h accumulated QPF fields initialized at 00 UTC daily from 18 December 2008 – 15 December 2009. Traditional verification metrics computed for this test included frequency bias and Gilbert Skill Score. Two advanced spatial techniques were also examined – the Method for Object-based Diagnostic Evaluation and the Fraction Skill Score – in an attempt to better associate precipitation forecast performance differences with different model horizontal scales.

Faculty and students are encouraged to attend.