Global Predictability of Daily Rainfall

Abstract:

Currently the factors leading to strong and unpredictable rainfall are not very well understood. We have analyzed the predictability of precipitation simulated with the super-parameterized version of the Community Atmosphere Model (SP-CAM) with ten Cloud-Resolving Models (CRMs) running in parallel in each CAM grid column. We used daily rainfall. The coefficient of variation (the ratio of the standard deviation to the ensemble mean) of the daily rainfall was compared to various parameters including the vertical shear of the horizontal wind, the convective available potential energy (CAPE) and the Richardson Number. We found a high correlation between the CAPE and the coefficient of variation. Hourly time series for each grid point were analyzed to determine whether the rainfall behaves chaotically. The results are inconclusive.