Diagnosing Climate Change from Above Using the Middle Atmosphere Climate Feedback Response Analysis Method

Abstract:

We present a new method to diagnose climate forcing and responses by focusing on the very sensitive middle atmosphere. We extend the recently developed climate feedback-response analysis method (CFRAM) to the middle atmosphere (MCFRAM) to quantify the temperature changes contributed from the external forcing and different feedback processes in the middle atmosphere climate system. The MCFRAM is applied to two sets of data to diagnose the middle atmosphere climate sensitivity. One is the temperature and ozone fields measured by the Sounding of the Atmosphere using Broadband Emission Radiometer and the other is the model output fields derived from the Goddard Earth Observing System chemistry-climate model (GEOSCCM). It is found that the globally averaged partial temperature change due to all radiative processes is approximately equal to the observed temperature change, ranging from −0.5 K near 20 km to −1.5 K near 70 km from the solar maximum to the solar minimum, with the largest partial temperature change being due to the variation of the input solar flux. The temperature responses to variations of CO₂, O₃ and solar flux have distinctly different spatial structures. The seasonality of the middle atmosphere climate sensitivity is also presented using MCFRAM diagnosis based on the output fields by various ensemble runs of the GEOSCCM.