Satellite based remote sensing of halogens in the Arctic troposphere, under the impact of Arctic Amplification

• Main Author: Bougoudis, Ilias
• Other Authors: Wagner, Thomas, Burrows, John Philip, Vrekoussis, Mihalis
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2021
• Subjects: Halogens; Tropospheric Chemistry; Arctic; neural networks; Satellite Remote sensing; 530; 530 Physics; ddc:530; Hudson; Hudson Bay; Sea ice
• Online Access: https://media.suub.uni-bremen.de/handle/elib/5345; https://doi.org/10.26092/elib/1115; https://nbn-resolving.org/urn:nbn:de:gbv:46-elib53455

Bromine plays a crucial role in polar atmospheric composition. During springtime, photochemistry converts bromine compounds originating from ice and snow into gaseous reactive bromine radicals (Br), which deplete ozone in the boundary layer, forming bromine oxides (BrO). Due to the autocatalytic nature of the reaction mechanism, it has been called bromine explosion. The strong relationship of bromine photochemistry and release from its sources to ozone depletion events (ODEs) was discovered in the late 1980s. Since then, and because of the importance of tropospheric ozone (the primary source of hydroxyl radical (OH), the major oxidizing agent of the atmosphere), many studies focused on the mechanisms which release bromine into the troposphere and the driving parameters which enhance BrO production and therefore ozone depletion. Arctic Amplification (AA) is the phenomenon that surface temperature in high latitudes increases more rapidly than at lower latitudes. One of the most profound consequences of AA is the significant changes in sea ice conditions. Sea ice extent, age and thickness are drastically changing. Inevitably, all aspects of the Arctic ecosystem are expected to be affected by Arctic Amplification. Remote sensing from satellites can be extremely useful for studying the Arctic region. By the end of the 1970s, sea ice concentration was successfully monitored by satellite sensors. Since 1995, we also have the ability to study atmospheric composition worldwide with data retrieved from nadir radiance spectra from a series of European satellite sensors: GOME on ERS-2 (1995 - 2003), SCIAMACHY on ENVISAT (2002 - 2012), GOME-2A on MetOpA (2007 - today) and GOME-2B on MetOpB (2012 - today). The focus of this thesis is twofold: firstly, to create the first consolidated and consistent long-term (1996 to 2017) tropospheric BrO dataset for the Arctic region and the Hudson Bay (a well-known hotspot for bromine explosion events), retrieved from the four ultraviolet-visible (UV-VIS) sensors mentioned above, in order ...