Things to consider:
-- could be based on TKE or turbulence intensity from the CFD solver
-- will need something different for the conservation of mass solver
-- could also initialize with the forecast gust field or max wind speed (which is at least in the HRRR)
The gust is a diagnostic variable (calculated in HRRR/RAP as shown below) max wind speed is directly simulated. In recent work we found that the HRRR max wind speed compared better to observations than the mean wind or gust from HRRR and NDFD across CONUS.
On the algorithm to calculate the wind gust potential diagnostic: Within the PBL depth at a given (i,j) grid point at a given time (instantaneous wind profile), calculate the excess of wind speed in the profile over 10m surface speed at each level. Multiply this excess by a coefficient (f(z)) that decreases with height from 1.0 to 0.5 at 1 km height, and is 0.5 for any height > 1 km. Find and then add the maximum weighted wind excess within the PBL back to the surface wind. [gust = vsfc + max (f(z)*(v(k)-vsfc) ]
Things to consider:
-- could be based on TKE or turbulence intensity from the CFD solver
-- will need something different for the conservation of mass solver
-- could also initialize with the forecast gust field or max wind speed (which is at least in the HRRR)
The gust is a diagnostic variable (calculated in HRRR/RAP as shown below) max wind speed is directly simulated. In recent work we found that the HRRR max wind speed compared better to observations than the mean wind or gust from HRRR and NDFD across CONUS.
On the algorithm to calculate the wind gust potential diagnostic: Within the PBL depth at a given (i,j) grid point at a given time (instantaneous wind profile), calculate the excess of wind speed in the profile over 10m surface speed at each level. Multiply this excess by a coefficient (f(z)) that decreases with height from 1.0 to 0.5 at 1 km height, and is 0.5 for any height > 1 km. Find and then add the maximum weighted wind excess within the PBL back to the surface wind. [gust = vsfc + max (f(z)*(v(k)-vsfc) ]