Halogen radicals play an important role in the chemistry of the polar atmosphere. Ozone depletion in the stratosphere by man-made halocarbons is a well-known phenomenon. However, the destruction of ozone also occurs close to the ground. Tropospheric ozone depletion events are caused by bromine radicals emitted from the sea ice and occurs every spring both in the Arctic and Antarctic. In recent years, evidence has emerged that iodine radicals also play an important role in the chemistry of the Antarctic troposphere.

The phenomena halogen radicals are involved in were investigated at Neumayer for more than 10 years by the IUP-Heidelberg (PI: Udo Frieß) using a permanently operating Multi-Axis DOAS instrument installed on the roof of the trace gas observatory. It observes scattered sunlight from different viewing directions and detects atmospheric trace gases using their absorption structures as individual fingerprints. Using these measurements, it was possible to investigate the dynamics and vertical structure of bromine enhancements in polar spring in detail.

Mesopause temperatures

The infrared spectrometer GRIPS 15 (Ground-based Infrared P-branch Spectrometer) was set up at the Air Chemistry Observatory at the German Antarctic Research Station Neumayer III during the Antarctic summer campaign in February 2013 for monitoring the OH(3,1) rotational temperature in the mesopause region at about 87 km height.

The main objective is the long-term monitoring of climate change signals. The instrument is also well suited for the study of short-period atmospheric waves, i.e. gravity and infrasonic waves because of its high temporal resolution of 15 seconds per spectrum which is significantly below the atmospheric Brunt-Väisälä period.

GRIPS 15 is equipped with an InGaAs photodiode detector array. The instrument records atmospheric spectra with a rate of approximately 4 spectra per minute. The spectra cover the wavelength range between 1500 nm and 1600 nm. Since Neumayer is located at 70°S measurements are taken 24 hours 7 days a week during winter time, while in summer time the instrument is shut down because of polar day conditions.

The operation of GRIPS 15 and the scientific research is based on cooperation between the German Remote Sensing Data Center (DFD) at DLR and the Alfred-Wegener-Institute for Polar and Marine Research (AWI). With the installation of GRIPS 15 at the Air Chemistry Observatory, Neumayer III gets a member of the international Network for the Detection of Mesopause Change (NDMC).

The data products are archived at the World Data Center for Remote Sensing of the Atmosphere (WDC-RSAT). Quicklooks are available at the NDMC website.