A 100-yr CCM1 simulation of North China's hydrologic cycle

The year to year variability in North China's summertime hydrologic cycle is analyzed in a 100-yr CCMl simulation. Eastern North America is included for comparative purposes with earlier work. On the basis of the simulated inherent variability of the regionally averaged soil moisture, each year's climate pattern over these two regions is classified into one of three regimes: normal, dry, and wet. Features of the hydrologic cycle, the related large-scale atmospheric circulation, and the water budget are examined for each of the three defined climate regimes for each region. The relative importance of mechanisms leading to soil moisture anomalies over North China is found to be different from that over eastern North America. For North China, precipitation anomalies, which are related to large-scale circulation, appear to be relatively more important in determining soil moisture, and the preceding springtime soil moisture is of less importance. For eastern North America, the preceding springtime soil moisture anomalies, which help to induce subsequent changes in precipitation and the large-scale circulation, appear to be relatively more important. Overall, the processes yielding summertime hydrologic anomalies over North China are more complicated and less straightforward than for eastern North America.