Regional Response of the NCAR CCM1 to Anomalous Surface Properties

Abstract

Sensitivity tests of the National Center for Atmospheric Research (NCAR) Community Climate Model ¡V 1 (CCM1) response to surface forcing from sea surface temperature (SST) and soil moisture on precipitation are presented. Four experiments were performed, including a control experiment using climatological SSTs, an experiment with 1988 SSTs, which are generally though to have contributed significantly to the 1988 Drought in the United States, and experiments using an artificial soil moisture anomaly. For each experiment, three model simulations were performed, and were initialized form arbitrary conditions.

The results show that in CCMl, the 1988 SST experiment produced more precipitation in the United States compared to the control case. While precipitation increased in the U.S., the differences were found to be small compared to the variability. Control simulations with larger amounts of precipitation showed the strongest response to soil moisture anomalies; however, the seasonal reduction of soil moisture reduced the overall sensitivity to the imposed anomaly. Furthermore, soil moisture differences in regions other than the anomaly region developed with comparable magnitudes.

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