Regional Climatic Effects of Large-Scale Thermal Pollution: Simulation Studies with the NCAR General Circulation Model

Abstract

January and July experiments were performed with the NCAR general circulation model (GCM) to assess the potential climatic impact of the thermal energy released from a projected United States cast coast megalopolis circa 2000 A.D. The model has six layers in the vertical and a 5° latitude-longitude horizontal resolution. The ocean surface temperatures were held fixed with respect to time in both experiments at the appropriate observed climatological values for each month. To determine the statistical significance of the model response, sets of random perturbation experiments were performed for each month to obtain a measure of the model noise level (i.e., the estimated standard deviation of monthly means). Larger surface temperature changes are found in the January thermal pollution experiment. with a maximum of 12°C in the vicinity of the beat input. Smaller but still significant changes with a maximum of 3°C are found in the July experiment. Significant changes in precipitation and soil moisture also result in the prescribed change region. However, neither experiment produces any evidence of a coherent statistically significant downstream response or ?teleconnection? over the Atlantic Ocean or Europe. Although these experiments are not complete climate change experiments, in that the ocean surface temperatures and sea ice distributions are not permitted to respond to the inputed waste heat, they do demonstrate the sensitivity of a current ?state of the art? GCM to such surface forcing. Furthermore, the necessity of considering different seasons in performing climatic impact studies is made apparent by the vastly different model response in the January and July experiments with the identical prescribed change in surface forcing.