AWIPEV Arctic Research Base - Stratospheric Observations at Koldewey-Station

A rather important tool for frequent ozone observations is the balloon-borne ozonesonde. At the Koldewey-Station, ozone soundings are performed at least once per week, and during winter times normally three times per week. An electrochemical ozone sonde of type ECC 6A is used together with radiosondes Vaisala RS-90 (GPS windfinding system). Usually they are launched with rubber balloons TX1500. These sondes yield ozone profiles from the surface up to 35 km. The ozone soundings are part of the NDACC measurement program. Data of several ozone sonde stations are combined by the Match technique.

A high-resolution fourier transformation infrared (FTIR) spectrometer is used for determining columns of stratospheric trace gases such as ozone, HCl, HF, NO₂, HNO₃, ClONO₂, CFCs, etc. 
Absorption spectroscopy utilises the effect that trace gases absorb light at specific wavelengths. From the spectra obtained it is possible to establish the type and concentration of trace gaes in the troposphere and stratosphere. Infrared absorption spectroscopy is a well-proven method. The presence and concentration of many different gases can be determined simultaneously using this technique. It requires the sun as the source of infrared radiation. In order to measure the concentration of important trace compounds throughout the year, scientists at AWI have further developed the technique and now the moon can be used as source of infrared radiation during the polar night. Due to the low intensity of light from the moon compared to that from the sun (a ratio of about 1 to 100000), this technique is only applicable during two weeks around full moon and measurements have to be taken over a period of three hours in order to obtain spectra comparable to those obtained within 10 minutes using solar radiation. At polar latitudes, however, the moon is above the horizon for up to 24 hours a day during the full moon phase. The FTIR spectrometer was installed at the Koldewey-Station in March 1992. 
More about the FTIR technique 

Quasi-continuous observations of several atmospheric species are performed by measuring the absorption of visible and near ultraviolet sunlight scattered from the zenith sky or that from direct moonlight. Vertical column abundances of molecules such as ozone, NO₂, OClO, BrO and IO are derived by means of a Differential Optical Absorption (DOAS) algorithm and a radiative transfer model. These activities contribute to the calibration and validation studies of data from the GOME instrument on the ERS-II satellite and from future ENVISAT instruments.