The impact of stratospheric aerosol heating on the frozen hydrometeor transport pathways in the tropical tropopause layer

• Published in: Environmental research letters Vol. 19; no. 4; pp. 44039 - 44046
• Main Authors: Kroll, C A, Fueglistaler, S, Schmidt, H, Dauhut, T, Timmreck, C
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01-04-2024
• Subjects: Atmospheric and Oceanic Physics; Convection; deep convection; geoengineering; Gravity waves; heating perturbation; Hydrometeors; Low temperature; Moisture content; Physics; Stratosphere; stratospheric moisture budget; tropical tropopause layer; Tropopause; Upwelling; Velocity; Velocity distribution; volcano; Water content; Water vapor
• ISSN: 1748-9326; 1748-9326
• DOI: 10.1088/1748-9326/ad33d0

Abstract
The exceptionally low temperature in the tropical tropopause layer (TTL) restricts the amount of water vapor entering the stratosphere. However, moisture may also enter the stratosphere in its frozen state, and the amount thereof depends on hydrometeor sedimentation and air vertical velocity. We investigate the sensitivity of frozen hydrometeor transport pathways to substantial perturbations of the TTL temperature structure in global storm-resolving model simulations. A special focus is laid on the question which process—convection, slow upwelling within the background velocity field, in-cloud radiative processes, gravity waves or turbulence—is responsible for most of the transport. The study shows that the main contribution to the frozen hydrometeor flux is cold-point overshooting convection in both the control and perturbed scenario. The average convective event transports an increased amount of frozen hydrometeors at the cold-point tropopause, when the later is warmed. This finding can be explained by scaling of frozen moisture content with Clausius Clapeyron in a saturated environment.