Journal Club: 11-06-2019

This paper studied a case of extreme ramping that occurred in central USA in July 2011. The passage of a cold front, along with large instability triggered the formation of a mesoscale convective system. This resulted in strong gusts from downdrafts which caused extensive damage to the Buffalo Ridge wind farm.

Wind farm damage

This paper performance of different WRF PBL and microphysics schemes at representing this event. ERA-Interim renalysis data was downscaled for this event using WRF with 3 domains at 9km, 3km and 1km. 3 PBL schemes (YSU, MYJ and Shin-Hong) and 2 microphysics schemes (Ferrier-Aligo and WDM6) were tested. The Ferrier-Aligo is a more simplistic scheme with less classes of hydrometeor types compared to WDM6. The WRF data was analysed for the two innermost domains (3km and 1km).

Max wind speed from observation stations in “analysis region” (top) and the corresponding maximum WRF wind speed in the “analysis region”.

It was found that the highest resolution domain and most complex microphysics scheme (WDM6) produced the strongest wind speeds. Although the observed wind speeds did not pick up these strong wind speeds (top plot), apart from the black dots which lies outside the “analysis region” to the east. It was found that the high resolution (d03) with Ferrier-Aligo (FA) microphysics performed similarly to the coaser resolution (d02) and WDM6 (W6) for 10m winds. But when looking at the extremes of the profile, W6-d02 produces stronger winds aloft within the turbine layer than fa-d03.

Provides some possible methods for analysing high-res case studies.