Roux, Gregory, Yubao Liu, Luca Delle Monache, Tom
Hopson, William Y.Y. Cheng and Yuewei Liu, National Center for Atmospheric
Research/RAL
In support of Xcel
Energy wind power prediction, NCAR has implemented an operational E-RTFDDA system
(Ensemble Real-Time Four Dimensional Data Assimilation and forecasting system)
over the western-central states. The ensemble system runs with two nested
domains at 30 and 10 km grid intervals, and its fine-mesh 10-km domain covers
the Rocky Mountains from New Mexico to Montana, and also the western Midwestern
States, and most parts of the Central/South Plains. E-RTFDDA is a WRF and MM5
based multi-model, multi-perturbation approach ensemble system. E-RTFDDA is
able to produces ensemble 4D continuous data assimilation and forecasts. This
system has been running operationally since May 2010, with 6-hour forecast
cycles, providing forecasts at up to 48 hours in each cycle. In this study, the
operational E-RTFDDA forecast outputs during the year 2011 are verified against
the surface and upper-air weather observations, and the wind observations at
selected wind farms located in Minnesota, Colorado and Texas, which features
dramatically different weather regimes.
The research in this paper is focused on the ensemble forecast
performances in terms of the Òwind-rampÓ probabilistic forecast using the raw
ensemble model output, and the ÒclimatologicalÓ characteristics of several WRF
physics settings. The additional skills from an ensemble calibration process based
on an analog-based bias-correction and a quantile-regression algorithm will
also be discussed.