65th IHC Booklet/Program (pdf - 4.9MB) - Office of the Federal ...

Ensemble-based prediction and diagnostics during the PREDICT field experiement
Sharanya J. Majumdar 1 , Ryan D. Torn 2 , Fuqing Zhang 3
(smajumdar@rsmas.miami.edu)
1 Rosenstiel School of Marine and Atmospheric Science, University of Miami;
2 University at Albany, State University of New York;
3 Department of Meteorology, Penn State University
During the NSF-sponsored PRE-Depression Investigation of Cloud-systems in the
Tropics (PREDICT) field experiment, which took place during August-September 2010, a
variety of synoptic-scale, mesoscale and convective-scale products based on ensemble forecasts
were disseminated. In addition to operational global ensemble forecasts provided by ECMWF
and NCEP, new higher-resolution, data-assimilative Weather Research and Forecasting
ensembles initialized using the Ensemble Kalman Filter (WRF/EnKF) were also run in real-time.
With the primary focus of PREDICT being to test the 'marsupial' theory on how clusters of
thunderstorms organize into tropical depressions, ensemble mean and probabilistic measures of
low-level circulation and thickness anomaly were provided to yield quantitative estimates of
fields relevant to genesis. Other products included probability distributions of vertical wind
shear, relative humidity, and upper-level divergence, and spaghetti contours of the curvature of
the flow via the Okubo-Weiss parameter. The utility of all these ensemble products will be
presented for the disturbance that eventually became Hurricane Karl, together with preliminary
evaluations of the ensembles' abilities to quantitatively predict metrics relevant to genesis.
Session 6 – Page 7