P-1

Numerical prediction experiment of cumulus convection by upstream lower-level humidification

Y. Wakazuki (University of Tsukuba)

A short-term precipitation prediction (nowcast) method was developed by using upstream low-level humidification (ULH) in a cloud-resolving atmospheric model simulation. The ULH plays a role in the approximated adjoint calculation for time-integration of four-dimensional variational data assimilation. This method was applied to a heavy rainfall event observed in the Kanto Plain on September 2, 2013. The heavy rainfall caused by a few cumulonimbus clouds was predicted by the ULH well before 30 minutes or more. The upstream advection period of 20 or 30 minutes was appropriate for more accurate prediction. The predicted cumulonimbus cloud included the large vertical vorticity which is seems to be associated with the observed tornado.