Projects/Activities

The aim of the project is to perform solar and lunar absorption measurements of atmospheric trace gases for the valdation of the SCIAMACHY satellite. Besides the routine observations within the NDSC it is planned to perform more intense measurements, especially during the satellite overpasses.

By launching several hundred ozonesondes and by ozone lidar measurements at many Arctic and sub-Arctic stations, one of them Ny-Ålesund, the stratospheric chemical ozone loss will be determined. The launches of all stations will be coordinated by analysis of trajectory calculations based on analysis and forecast wind fields. The aim is to get as many ozone sounding pairs as possible, each of them linked by trajectories in space and time. A statistical description of the ozone differencies given by the first and the second measurement of individual sonde pairs will yield the chemical ozone loss with spatial and time resolution. Four similar campaigns took place in the Arctic and in the mid-latitudes covering the time period of Januar to March in each of the last four winters. In the first three winters high ozone depletion rates (20 - 50 ppbv per day) were determined in some height levels within the polar vortex. In the height level of the ozone maximum an integrated ozone loss (during the winter) in the order of 60 % have been found. These are record ozone losses for the Arctic polar region. In the last winter the ozone depletion rates had been much lower due to moderate temperatures in the stratosphere.

The FTIR (Fourier Transform Infrared Spectroscopy) has been established as a powerful tool for measurements of atmospheric trace gases. Using the sun or moon as light source, between 20-30 trace gases of the tropo- and stratosphere can be detected by their absorption features. The analysis of the spectra allow to retrieve the total zenith columns of the trace gases. The aim of the SAMMOA project is to study the stratospheric ozon depletion during the summer time period. While the processes during winter/spring are investigated in detail the summertime ozone loss has not been studied so far. Therefore FTIR solar absorption measurements of ozone and related species are to be done on much more observation days beside the routine observations within the NDSC

Quasi-continuous observation of several atmospheric species are performed by measuring the absorption of visible and near ultraviolet sunlight scattered from the sky or in direct moonlight. Column abundance of molecules such as ozone, NO2, OClO, NO3, BrO, HCHO and IO are derived by means of a Differential Optical Absorption (DOAS) algorithm and a radiative transfer model. These activities are part of calibration and validation studies of different satellite experiments (GOME, SAGE III, SCIAMACHY). Since 1999 the instrument is part of the Network of the Detection of Stratospheric Change (NDSC). The instrument has been installed in 1995 as the second UV/vis instrument from the Institute of Environmental Physics. One similar setup in Bremen is continuously running with the exception of short maintenance breaks since 1993.

Photoinhibition of photosynthesis by UV radiation, the formation of UV-screening pigments, DNA damage by UV radiation as well as DNA repair mechanisms will be determined in marine macroalgae of the Kongsfjord. Moreover, algae from different water depths will be transplanted by divers into areas with opposite light climate or covered by UV-screening filters and their physiological reactions tested. Additionally, the susceptability of the unicellular algal spores to UV-radiation will be tested. The results will allow insights into the effect of UV and photosynthetically active radiation on the zonation of macrocalgae and on the structure of phytobenthic communities. The data will be used to model the effects of increased of UV-radiation due to stratospheric ozone depletion on the Kongsfjord phytobenthic communities.

The changes in the stratospheric ozone layer due to anthropogen emissions lead to an increasing insolation of sunlight in the UV-B range (280nm - 320nm) on ground. One of the major objects of UV-B measurements is to detect long-term trends. The most interesting areas corresponding to ozone depletion are Antarctica and more recently the region around the northern pole. In interdisciplinary cooperation the data are also basis for research in the effects of increasing UV-B doses on plankton, algae, and other organisms. Since 1998 additional measurements of UV-A radiation (320-400nm) are done.

The FTIR (Fourier Transform Infrared Spectroscopy) has been established as a powerful tool for measurements of atmospheric trace gases. Using the sun or moon as light source, between 20-30 trace gases of the tropo- and stratosphere can be detected by their absorption features. The analysis of the spectra allows to retrieve the total zenith columns of the trace gases. For a few trace gases the pressure broadening of the lines allows to get additionally some information on the vertical concentration profiles. Some important trace gases cannot be detected in the IR but in the UV/VIS. This makes it useful to record the whole spectral region from the IR from about 700/cm (14 µm) to the UV at 33000/cm (300 nm).

Microwave radiometers are part of the standard instrumentation at primary NDSC stations and are due to their long-term stability and self calibrating technique especially useful for monitoring purposes. Altitude profiles are retrieved from the shape of the pressure broadened thermally induced emission line of the observed species. The instruments for the observation of stratospheric ozone, chlorine monoxide and water vapour at the Koldewey Station in Ny-Ålesund were developed at the University of Bremen and upgrades and improvements are regularly carried out. The instruments have been automated during recent years and ozone and water vapour observation on Spitsbergen are carried out all year round. Chlorine monoxide is only observed in late winter and early spring, when enhanced concentrations in the lower stratosphere are to be expected. Routine operation and maintenance are done by the station engineer. Data analysis is carried out at the University of Bremen.

The Baseline Surface Radiation Network (BSRN) is a cooperative network of surface radiation budget. Measurement stations operated by various national agencies and universities under the guiding principle set out by the World Climate Research Programme (WCRP). Presently about 15 stations have been established, one of them is Ny-Ålesund. The concept for a Baseline Surface Radiation Network has developed from the needs of both the climate change and satellite validation communities. The aims of the programme are the monitoring of long-term trends in radiation fluxes at the surface and the providing validation data for satellite determinations of the surface radiation budget. The BSRN station Ny-Aalesund was installed in summer 1992 and is regularly operating since August 1992.

Stratospheric aerosols like Polar Stratospheric Clouds (PSCs) or volcanic aerosols are investigated by different types of balloon borne sensors in co-operation with the University of Nagoya, Japan, and the University of Wisconsin, Laramie, Wisconsin. The sensors flown are dedicated optilca particle counters (OPC) or backscatter sondes (BKS), respectively.

SAGE III was successfully launched on 10. Dec. 2001 on a Russian M3 rocket. It provides accurate data of aerosols, water vapour, ozone, and other key parameters of the earth's atmosphere. The science team of the SAGE III experiment at NASA has nominated the Koldewey-Station as an anchor site to contribute within the Data Validation Plan as part of the Operational Surface Networks. Data directly relevant to the SAGE III validation are aerosol measurements by photometers and lidar, as well as temperature measurements and ozone profiling by balloon borne sondes, lidar and microwave radiometer. Data will be provided quasi online for immediate validation tasks.

In preparation to the launch of the SAGE III experiment in March 2001, NASA and the European Union performed the SOLVE/THESEO-2000 campaign, which had three components: (i) an aircraft campaign using the NASA DC-8 and ER-2 airplanes out of Kiruna/Sweden, (ii) launches of large stratospheric research balloons from Kiruna, (iii) validation exercises for the commissioning phase of SAGE III. The German Arctic research station Koldewey in Ny-Ålesund/Spitsbergen contributed to (i), (ii), and (iii) by performing measurements of stratospheric components like ozone, trace gases, aerosols (PSCs), temperature and winds. The main observation periods were from December 1999 to March 2000.

The stratospheric multi wavelength LIDAR instrument, which is part of the NDSC contribution of the Koldewey-Station, consists of two lasers, a XeCl-Excimer laser for UV-wavelengths and a Nd:YAG-laser for near IR- and visible wavelengths, two telescopes (of 60 cm and 150 cm diameter) and a detection system with eight channels. Ozone profiles are obtained by the DIAL method using the wavelengths at 308 and 353 nm. Aerosol data is recorded at three wavelengths (353 nm, 532 nm, 1064 nm) with depolarization measurements at 532 nm. In addition the vibrational N2-Raman scattered light at 608 nm is recorded. As lidar measurements require clear skies and a low background light level, the observations are concentrated on the winter months from November through March. The most prominent feature is the regular observation of Polar Stratospheric Clouds (PSCs). PSCs are known to be a necessary prerequisite for the strong polar ozone loss, which is observed in the Arctic (and above Spitsbergen). The PSC data set accumulated during the last years allows the characterization of the various types of PSCs and how they form and develop. The 353 and 532 nm channels are also used for temperature retrievals in the altitude range above the aerosol layer up to 50 km.