Zhu, Jiangshan, Center for Analysis and Prediction of
Storms, University of Oklahoma, Institute of Atmospheric Physics, Chinese Academy of
Sciences, Beijing, China, Fanyou Kong, Xuguang Wang, CAPS and University of
Oklahoma, Jeff Duda, University of Oklahoma, Judith Berner, NCAR, Ming Xue,
CAPS and University of Oklahoma
The newly available
stochastic kinetic-energy backscatter (SKEB) perturbation in the Weather
Research and Forecasting Model version 3.3.1 has been applied through a
5-member, storm-scale ensemble forecasting (SSEF) system that covers the full
continental United States with 4-km grid spacing during the 2012 NOAA HWT
Spring Experiment, to investigate the impact of the SKEB perturbation on SSEF
system. The SKEB members are evaluated against a group of same 5-member
non-SKEB members through the HWT Spring Experiment period. Different SKEB
perturbation amplitudes and different vertical structures are examined through
a severe storm case of April 27, 2011 to reveal the SKEB perturbation growth at
the convection-permitting model resolution and to look for possible optimal
SKEB configuration for the SSEF system. The case study shows that the
SKEB-induced perturbation growths are more prominent in active convection area,
suggesting moist convective instability intensifies the perturbations from
SKEB. Doubling the SKEB perturbation amplitudes leads to much larger overall
perturbation intensity and more broader spatial extent and has more intensive
impact than halving the perturbation amplitudes. In general, adding SKEB
perturbations does not change the overall precipitation distribution, but can
cause displacement of the local maxima. The overall impact of SKEB on the
storm-scale ensemble forecasting system through the HWT experiment period has
been evaluated and will be presented at the workshop.