Precipitation Forecast Improved with a New Convective Triggering Mechanism
Xie, S., Lawrence Livermore National Laboratory
General Circulation and Single Column Models/Parameterizations
Xie, S, and M Zhang. 2000. "Impact of the convective triggering function on single-column model simulations." Journal of Geophysical Research 105: 14983-14996.
Six-hour accumulated precipitation valid at 12 UTC 18 July 2005. (a) Radar Observation, (b) DCAPE, (c) GSM without the DCAPE trigger, and (d) GSM with the DCAPE trigger. Considerable improvement of precipitation forecast is obtained by the GSM with the new trigger compared to the radar observation. (Courtesy of Dr. Masayuki Nakagawa/Japan Meteorological Agency.)
An improved convective triggering mechanism developed by ARM scientists ba
With the new triggering mechanism, the revised JMA’s GSM (T959L60DCP) substantially reduced the precipitation bias in the original T959L60 global model, which tends to overestimate weak precipitation area especially from local noon to late afternoon over Japan (See Figure 1). The predicted geographic distribution of precipitation and the intensity of strong precipitation events by T959L60DCP are much closer to observations than the original model.
Since November 2007, the new convective triggering mechanism has been used in the JMA’s global model for operational weather forecasts.