The Response of Stratospheric Water Vapor to Climate Change Driven by Different Forcing Agents
Abstract
We investigate the response of stratospheric water vapor (SWV) to forcing agents with different physical properties within the Precipitation Driver and Response Model Intercomparison Project (PDRMIP) framework. For each model and forcing agent, we break the SWV response into a slow response, which is coupled to surface temperature changes, and a fast response, which is the direct response to external forcing, but without any mediation from the surface temperature. Our results show that, for most climate perturbations, the slow SWV response dominates the long-term change of SWV in both the tropical lower stratosphere (TLS) and the lowermost stratosphere (LMS). The slow SWV component responds to different forcing agents with a similar efficacy. The slow SWV response is largely controlled by the surface temperature, and it exhibits a similar sensitivity across all climate perturbations, which is 0.35 ppmv/K in the TLS, 2.1 ppmv/K in the Northern Hemispheric LMS, and 0.97 ppmv/K in the Southern Hemispheric LMS. Most climate perturbations produce close to zero fast SWV response. The fast SWV response only dominates the slow SWV response when the forcing agent radiatively heats the cold point region – for example, black carbon, which directly heats the atmosphere by absorbing solar radiation. The fast SWV response in the TLS is primarily controlled by the fast adjustment of cold point temperatures across all climate perturbations, with a sensitivity of 0.52 ppmv per degree of cold point warming. This control becomes weaker at higher altitudes and at higher latitudes below 150 hPa.
Citation
Wang, Xun (2020). The Response of Stratospheric Water Vapor to Climate Change Driven by Different Forcing Agents. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /192707.