A 100-YR CCM1 SIMULATION OF NORTH CHINA HYDROLOGIC-CYCLE

The year to year variability in North China's summertime hydrologic cy cle is analyzed in a 100-yr CCMl simulation. Eastern North America is included for comparative purposes with earlier work. On the basis of t he simulated inherent variability of the regionally averaged soil mois ture, each year's climate pattern over these two regions is classified into one of three regimes: normal, dry, and wet. Features of the hydr ologic cycle, the related large-scale atmospheric circulation, and the water budget are examined for each of the three defined climate regim es for each region. The relative importance of mechanisms leading to s oil moisture anomalies over North China is found to be different from that over eastern North America. For North China, precipitation anomal ies, which are related to large-scale circulation, appear to be relati vely more important in determining soil moisture, and the preceding sp ringtime soil moisture is of less importance. For eastern North Americ a, the preceding springtime soil moisture anomalies, which help to ind uce subsequent changes in precipitation and the large-scale circulatio n, appear to be relatively more important. Overall, the processes yiel ding summertime hydrologic anomalies over North China are more complic ated and less straightforward than for eastern North America.