Koldewey Station, Ny-Ålesund/Spitsbergen: projects/activities

The project aims at producing an ENVISAT-1 mission-long monitoring of the inorganic chlorine (Cly) and fluorine (Fy) loading in the Earth’s middle atmosphere, based on FTIR vertical column abundance measurements of the key related species HCl, ClONO2, HF and COF2 at 10 ground-based NDSC sites distributed worldwide. These Cly and Fy inventories will be completed with ClO and OClO measurements expected as Level-2 products from ENVISAT-1. The column abundances of the source gases CFC-12 and HCFC-22 will be used to place the stratospheric Cly and Fy evolution in perspective with the more complete sets of organic chlorinated and fluorinated compounds measured at the ground by the in situ networks NOAA-CMDL and AGAGE. The assimilation of the retrieved geophysical data bases will be performed through 3-D model calculations incorporating physical, chemical and transport characteristics of the global atmosphere.

The present project aims at the geophysical validation, from pole to pole and on the long term, of key ozone-related level-2 products (O3, NO2, BrO, OClO, and ClO) from GOMOS, MIPAS and SCIAMACHY onboard ENVISAT-1, and at a contribution to the maturation of the related level-1b-to-2 data processors. Application data processing will be used to convert level-2 data into a more suitable format for validation and scientific end-users. The respective performances of the ENVISAT data products, and their sensitivity to various relevant parameters, will be investigated from the Arctic to the Antarctic, over a variety of geophysical conditions. The impact of these performances on specific atmospheric chemistry studies will be emphasised. The pseudo-global investigations will rely on correlative studies of ENVISAT data with high-quality ground-based, in situ and balloon observations associated with the Network for the Detection of Stratospheric Change (NDSC).

The project will provide a long-term, pseudo-global validation support to the ENVISAT-1 atmospheric measurements, based on mutually consistent high-quality solar and lunar observations from FTIR spectrometers operated at primary and a number of complementary NDSC stations. The validation is limited to a number of target species, most of which are primary NRT or OL level-2 products of the mission, with focus on NOy components: O3, NO2, NO, N2O, HNO3, HNO4, H2CO, CO and CH4. Synergistic use will be made of column and profile data from MIPAS, GOMOS and SCIAMACHY. The ground network will deliver mean vertical column abundances for all target species with NDSC-type quality, and height profile information for some target gases as secondary products to the PI's home institute, where the correlative analyses with the ENVISAT-1 products will be done. Asynoptic mapping tools will support the validation efforts.

SOGE is an integrated system for observation of halogenated greenhouse gases in Europe. There are two objectives: (1) To develop a new cost-effective long-term European observation system for halocarbons. The results will be in support of the Kyoto and the Montreal protocols,in assessing the compliance of European regions with the protocol requirements. In particular the observation system will be set up to: - detect trends in the concentrations of greenhouse active and ozone-destroying halocarbons; - verify reported emissions and validate emission inventories; - develop observational capacity for all halocarbons included in the Kyoto protocol (PFC, SF6) for which this is presently not yet existing; - develop a strategy for a cost-effective long-term observation system for halocarbons in Europe. (2) To predict and assess impacts of the halocarbons on the climate and on the ozone layer. This implies extensive exploitation of existing data. The impact assessment will be aimed at providing guidance for development of the Kyoto protocol and to the further development of the Montreal protocol mendments, by: - modelling impacts of halocarbons on radiative forcing and their relative importance for climate change; - modelling impacts of emissions of CFCs and HCFCs on the ozone layer.

The main specific objectives of UFTIR are: (1) To revise and homogenise the analyses of available experimental data for providing consistent time series of distinct tropospheric and stratospheric abundances of the target gases using new inversion algorithms. A common strategy for retrieval and characterisation of the vertical distributions of the target gases from FTIR ground-based measurements will be established. (2) To provide quantitative trends and associated uncertainties for the target gases over about the last decade, as a function of latitude throughout Western Europe, focusing on the troposphere. (3) To integrate the data in model assessments of the evolutions of tropospheric abundances. The measured burden and changes of the tropospheric gases will be compared with 3D model simulations, in order to help developing the latter, assist in explaining potential causes for the observed changes and to assess the consistencies between the trends at the surface to the free troposphere and lowermost stratosphere, and the agreement with known evolutions of emissions. UFTIR will make the community prepared to deliver tropospheric data for validation and synergistic exploitation of new satellite experiments like ENVISAT.

By launching several hundred ozonesondes 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 differences given by the first and the second measurement of individual sonde pairs will yield the chemical ozone loss with spatial and time resolution.

In december 2001 the SAGE III experiment was successfully launched. The NASA science team of the SAGE III experiment has announced the Koldewey-Station in Ny-Aalesund as "anchor site" for validation, especially for such parameters as optical depth, aerosol extinction profiles and ozone profiles. Because of time coincidence NASA apprechiates support for the prospected validation activities for ENVISAT. This should be also considered as contribution to the NASA accepted project "Ground based Validation of SAGE III by the NDSC Primary Station at Ny-Ålesund, Spitsbergen" for SOLVE-2.

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 excercises for the commissioning phase of SAGE III. The German Arctic research station Koldewey in Ny-Ålesund/Spitsbergen contributes to (i), (ii), and (iii) by performing measurements of stratospheric components like ozone, trace gases, aerosols (PSCs), temperature and winds. The measurement results were transmitted quasi online to the flight planning center in Kiruna, in order to allow a better directing of the air plane flights. In addition the Koldewey-Station has been designated a validation anchor site for the SAGE III validation. The activities are organized within a NASA accepted proposal of ground-based validation support by the NDSC Primary Station at Ny-Ålesund, Spitsbergen and by a SAGE III validation working group for Ny-Ålesund. The main observation periods are from December 1999 to March 2000.

In order to get detailed vertical ozone profiles above the range of standard electrochemical ozonesondes (typically 35 km), a radiosonde together with an optical ozonesensor is launchend with a special plastic foliage balloon. The balloon payload consists of a digital radiosonde (DFM 90) using GPS for altitude measurements and a two channel filter spectrometer (optical sensor) to measure the vertical ozone distribution up to more than 40 km altitude. The ozone profiles obtained by the optical sensors will be compared with ground-based microwave and lidar ozone observations as well as with the standard balloon-borne ozone measurements with electrochemical ozone sensors.

Aim of the project is to develop a cost-effective long-term European observation system for halocarbons and to predict and assess impacts of the halocarbons on the climate and on the ozone layer. Beside the routine observations within the NDSC it is planned to perform with FTIR (Fourier Transform Infrared Spectroscopy) absorption measurements of CFCs (e.g. SF6, CCl2F2, CHF2Cl) and related species on much more observation days.

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.