Design, function, and applicability of a new multiple axis-differential optical absorption spectrometer for observing halogen chemistry in the Arctic

Abstract

"Every springtime reactive halogen species (e.g. bromine atoms and bromine monoxide radicals, BrO) are photochemically released into the Arctic atmosphere by heterogeneous reactions on snow/ice surfaces. These halogens subsequently alter the chemical pathways of the atmosphere by depleting ozone levels to near zero, taking over as the primary oxidizer. An autocatalytic chemical mechanism for the release of reactive halogens from ice surfaces has been described; however, the environmental conditions that lead to halogen production are still unclear, limiting our ability to understand and predict these halogen chemical events. This thesis describes the design and operation of a new autonomous multiple axis-differential optical absorption spectrometer (MAX-DOAS) instrument, which is capable of long term data collection at remote unmanned locations. Novel design features include frost detection and removal, instrumental tilt correction, an enclosed optical scan head, robust data acquisition software, satellite communications compatibility, and low power consumption (~3 Watts). Laboratory and field tests demonstrate that this new instrument is capable of producing high quality BrO measurements. This instrument holds great promise for furthering our understanding of reactive halogens in the polar regions, in particular through investigations of environmental conditions leading to halogen release as well as by validating and improving satellite methods"--Leaf iii