Organic, inorganic and total bromine in the extratropical tropopause and lowermost stratosphere in fall 2017: Origins, transport pathways and consequences for ozone
HALO Research Aircraft
Meike Rotermund
Online Zoom

In this talk I will present inferred total bromine measurements in the upper troposphere and lower stratosphere from a research aircraft over the North Atlantic and north western Europe in fall 2017 during the WISE (Wave-driven ISentropic Exchange) campaign. When taking a closer look into organic and inorganic bromine, as well as simultaneously measured transport and air mass lag-time tracers, the observations suggest that bromine-rich air masses persistently protruded into the lower stratosphere in the fall creating a high bromine region (HBrR) at mid-latitudes. The most probable source region is former tropical upper tropospheric air masses where elevated bromine was also observed. A secondary smaller source is transport across the extratropical tropopause. Lagrangian transport modelling is used to quantify these multi-pathway contributions to the lower stratosphere and specifically to the HBrR. Further, the influences of the Asian monsoon and its tropical adjacent regions as well as tropical cyclones from Central America on bromine are discussed. And lastly, I will talk about the consequences on ozone due to additional bromine transported into the lower stratosphere simulated with a global chemistry transport model.