Using the climate feedback response analysis method to quantify climate feedbacks in the middle atmosphere

Over recent decades it has become clear that the middle atmosphere has a significant impact on surface and tropospheric climate. A better understanding of the middle atmosphere and how it reacts to the current increase in the concentration of carbon dioxide (CO.sub.2) is therefore necessary. In this study, we investigate the response of the middle atmosphere to a doubling of the CO.sub.2 concentration, and the associated changes in sea surface temperatures (SSTs), using the Whole Atmosphere Community Climate Model (WACCM). We use the climate feedback response analysis method (CFRAM) to calculate the partial temperature changes due to an external forcing and climate feedbacks in the atmosphere. As this method has the unique feature of additivity, these partial temperature changes are linearly addable. In this study, we discuss the direct forcing of CO.sub.2 and the effects of the ozone, water vapour, cloud, albedo and dynamical feedbacks.