The Influence Of Interannual Soil Moisture Anomaly On Climate Potential Predictability

By using the NCAR global atmospheric general circulation model CAM3.1, the possible impacts of soil moisture on short-term climate potential predictability is investigated in the present study via numerical experiments. One control experiment named A, runs with interactive soil moisture boundary conditions, and the other sensitivity experiment named AWA is performed with the mean climatology state of the soil moisture. By using signal to noise ratio method contrasts control and sensitive experiment to discuss the effects of soil moisture anomaly on climate predictability. The main conclusions are summarized as follows:The CAM3.1model generally has good performances in simulating the climate potential predictability. The great value of potential predictability during spring and summer distributes in tropical regions with bands, and mainly concentrated in south hemisphere in spring and in north hemisphere in summer. The potential predictability of global land surface is higher in summer than in spring, and the potential predictability of500hPa height field is higher than that of temperature and precipitation. The model can simulate the potential predictability during spring over North America and in summer over Eurasia. Potential predictability of temperature is better than that of precipitation. In addition, the model simulations of potential predictability in ENSO years are higher than that in non-ENSO years, and are obvious in spring over North America and in summer over Eurasia.Climate variability and potential predictability are sensitive to soil moisture anomaly. The anomaly of the soil moisture increases the variability of temperature over Eurasia and North America and the variability of precipitation is varied with areas. It’s found that the climate variability over Eurasia and North America in ENSO yeas is greater than that in non-ENSO years. In addition, considering soil moisture interannual variability will increase potential predictability during summer over Mongolian plateau and in spring over North America, it occurrences significantly in ENSO years and apparently over North America, but decrease in non-ENSO years.The surface energy flux (surface net radiation flux, surface thermal flux, surface latent heat flux) and atmospheric circulation field (500hPa height field) over Mongolian plateau area and the United States is very sensitive to the soil moisture change. When soil moisture increases (decreases), surface net radiation flux and thermal flux and500hPa height field over Eurasia and North America decreases (increases), surface latent heat flux increases (decreases), that leads to the falling (rising) of temperature and diminishing (enhancement) of precipitation, finally influences the potential predictability significantly. ENSO events alter the changes in soil moisture over Eurasia and North America, then results in the changes in the variability of the temperature and precipitation. As a result, soil moisture interannual variability amplifies the impact of ENSO events on climate potential predictability over the central areas of Eurasia in summer and central America in spring.