How the Hunga Tonga—Hunga Ha'apai Water Vapor Cloud Impacts Its Transport Through the Stratosphere: Dynamical and Radiative Effects
Ulrike Niemeier, Sandra Wallis, Claudia Timmreck, Trang Van Pham, Christian von Savigny
Abstract
Abstract The eruption of the Hunga Tonga—Hunga Ha'apai (HTHH) volcano on 15 January 2022 injected about 150 Tg of water vapor (H 2 O), roughly 10% of the background stratospheric H 2 O content, to altitudes above 50 km. Simulations of the spatial evolution of the H 2 O cloud with the ICON‐Seamless model are very close to observations from the Aura Microwave Limb Sounder. The vertical transport of the H 2 O cloud had three phases: an initial subsidence phase, a stable phase, and a rising phase. Radiative cooling of H 2 O clearly affects the transport of the H 2 O cloud, as demonstrated with passive tracers, and is the main driver within the subsidence phase. It also counteracts the large‐scale rising motion in the tropics, leading to the stable phase, and modulates the large‐scale transport of the H 2 O cloud for about 9 months. This holds for different QBO phases, where the H 2 O cloud differs mainly in its vertical extent.