Persistent Features of Drought Strength in North China and Its Prediction

Based on the analysis of persistent features of drought strength in North China, a new technique to predict the drought strength with an integration of both the droughty trend and the dynamic strong signal is proposed. Considering the prominent interdecadal and interannual variations of drought strength, which can be separated by means of a nonlinear dynamic reconstruction, the two models with different time scale to predict droughty trend are established respectively and integrated at last. In the course of model building,a concept of dynamic strong signal is introduced, and the strong signal of observable difference between previous fields of atmosphere and ocean and multi-year average values is introduced into the prediction model. It is indicated that the abnormal variations of atmosphere and ocean in the near future may influence the drought. The extraseasonal hindcasts from 1996 to 2002 show that the prediction model represents the droughty trend preferably and exhibits higher prediction skill.