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  • The field experiment ARKTIS 1993 was the third one in a series of experiments in the Arctic region performed by a group of climate researchers from Hamburg. The campaign took place in the Greenland Sea west of Spitsbergen from 1 to 25 March 1993. The preceding experiments were ARKTIS 1988 (5 - 25 May 1988) in the same geographic region and ARKTIS 1991 (20 February - 13 March 1991) located between North Norway and Bear Island. The main objective of ARKTIS 1993 was the investigation of cold air outbreaks from the Arctic sea ice onto the open water, in this case the West Spitsbergen current. To get a concise picture of all stages of boundary layer modification in cold air outbreaks a wide variety of measurement platforms was employed. Three reseach vessels (Polarstern, Valdivia, Prof. Multanovsky) operated in the experimental area providing surface observations and radiosonde data. Aerological data was also collected at three land stations (Bear Island, Danmarkshavn, Ny Alesund) which intensified their operational radiosonde program. Most essential measurement were taken by the research aircraft Falcon and DO-128 which took profiles and cross sections within the air flow. Eleven flight missions were performed.

  • The FRAMZY 2008 experiment aimed at the measurement of the sea ice drift in the Fram Strait and its relation to the atmospheric forcing, primarily to that by cyclones. FRAMZY 2008 was the fourth experiment with this objective and followed the FRAMZY experiments in 1999, 2002 and 2007. On 20 January 2008, seven CALIB (Compact Air-Launch Ice Buoys) buoys were deployed from a transport aircraft in a regular array of 200 km by 100 km size centered at 82.6¿N, 1.0¿E in the northern part of Fram Strait. Buoys measured autonomously air pressure, temperature and position at approximately one-hourly intervals and transmitted the data via the Argos satellite system. The lifetime of the buoys before they were lost at the ice edge or due to the breaking of ice was between 7 and 39 days (final date 28 February 2008). The southernmost position reached by a buoy after 39 days was 76.2¿N, -12.0¿E, corresponding to an average drift speed of 16.9 km per day or 0.20 ms-1. During the FRAMZY 2008 period eight cyclones passed through Fram Strait. The paper presents details of the ice motion and the atmospheric conditions. In the appendix 12-hourly maps of sea-level pressure and surface air temperature as analysed by the ECMWF, daily maps of ice concentration and daily NOAA satellite images are presented.

  • The field experiment DAMOCLES 2007 (Hamburg Arctic Ocean Buoy Drift Experiment DAMOCLES 2007-2008) consisted of the deployment and tracking of an array of 16 drifting autonomous buoys in the Central Arctic Ocean. The buoys were deployed in a quadratic array with 400 kilometres side length in the Siberian sector of the Central Arctic Ocean in April 2007. While drifting towards Fram Strait the buoys delivered at approximately 1-hourly time intervalls position, sea level pressure and temperature for several months with the last buoy transmitting until January 2008. The aim of the experiment was to study the Atmosphere-Ice-Ocean interaction, especially the impact of cyclones on the formation and transport of sea ice. DAMOCLES 2007 and DAMOCLES 2008 are a contribution to European integrated project DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies) which is funded by the European Union. DAMOCLES is a contribution to IPY 2007-2008 (International Polar Year).

  • The field experiment ARKTIS 1991 was an expedition planned by meteorologists of the Collaborative Research Centre 318 entitled "Climatically relevant processes in the system ocean-atmosphere-ice" which is funded by the German Research Foundation and established at the University of Hamburg. The expedition took place in the Norwegian Sea between Northern Norway, Bear Island and Jan Mayen during the period 17 February until 15 March 1991. The main aim of the experiment was the investigation of cold air outbreaks from the surrounding Arctic ice sheets. During such weather episodes the air mass coming from the ice is rapidly modified over the water due to the contrasts in temperature, heat conduction, humidity and roughness between ice and water. This leads to the formation of a "new" boundary layer. Its depth, mean temperature and moisture increases with increasing distance from the ice edge mainly due to sensible and latent heat supply from the ocean. The investigations of cold air outbreaks and Arctic stratus by scientists of the Collaborative Research Centre 318 began already three years before with the field experiment ARKTIS 1988 which took place in the area west of Spitsbergen in May 1988. ARKTIS 1991 is a continuation of this work under winterly weather conditions. ARKTIS 1991 was followed by the experiment ARKTIS 1993. As in ARKTIS 1988 the research vessel Valdivia and the two research aircraft FALCON-20 of the DLR at Oberpfaffenhofen and DO-128 of the TU Braunschweig were at our disposal. Radiosonde measurements were performed on board of RV Valdivia and on Bear Island.

  • The expedition ARKTIS 1988 was initiated and directed by the Collaborative Research Centre 318 of the German Research Foundation entitled "Climatically relevant proceses in the system ocean-atmosphere-ice" and established at the University of Hamburg. The field experiment took place in the Fram Strait in the area straddling the ice margin west of Spitsbergen during the period from 4 to 26 May 1988. The experimental concept for the investigation of boundary layer modification and certain cloud structures in cases of off-ice and on-ice air flows was to maneuver one ship, the research icebreaker POLARSTERN, about 100 km into the ice and to operate with a second ship, the research vessel VALDIVIA, in the open water near the ice edge. Several aircraft operating from the airport at Longyearbyen on Spitsbergen were intended to measure the mean structures, variances and covariances at different distances from the ice edge. ARKTIS 1988 was followed by the two experiments ARKTIS 1991 and ARKTIS 1993.

  • The field drift buoys experiment FRAMZY 2009 consisted of the deployment and tracking of an array of 7 drifting autonomous buoys, of which one did not transmit values. The experiment aimed at the measurement of the sea ice drift in the Fram Strait and its relation to the atmospheric forcing, primarily to that by cyclones. The buoys were deployed in October 2009 in the Fram Strait region and sampled data until February 2010. FRAMZY 2009 was the last one in a series of five field experiments (1999,2002,2007,2008) carried out in the frame of the Collaborative Research Centre 512 (Cyclones and the North Atlantic Climate System) funded by the German Science Foundation.

  • The field experiment DAMOCLES 2008 (Hamburg Arctic Ocean Buoy Drift Experiment DAMOCLES 2008-2009) consisted of the deployment and tracking of 9 drifting autonomous ice buoys in the Arctic Ocean. Seven buoys were deployed in the Canadian sector of the Arctic Ocean in late April 2008. Two more buoys were deployed in the Beaufort Sea and in the Laptev Sea in September and October 2008. The platforms report position, atmospheric pressure, temperature and humidity, wind speed and ice temperature at 3-hourly time steps. The last two buoys additionally report wind direction. The aim of the experiment was to study the Atmosphere-Ice-Ocean interaction, especially the impact of cyclones on the formation and transport of sea ice. DAMOCLES 2008 and its predecessor DAMOCLES 2007 are a contribution to European integrated project DAMOCLES (Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies) which is funded by the European Union. DAMOCLES is a contribution to IPY 2007-2008 (International Polar Year).

  • The drift buoys experiment FRAMZY 2007 consisted of the deployment and tracking of an array of 29 drifting autonomous buoys (16 ice, 13 water) in the Fram Strait region. The buoys were deployed in March 2007 and sampled data until end of April 2007. The aim of the experiment was to study the Atmosphere-Ocean interaction and the Atmosphere-Ice-Ocean interaction, especially the impact of cyclones on the energy budget of sea ice and ocean surface. FRAMZY 2007 was the third one in a series of five field experiments (1999,2002,2008,2009) carried out in the frame of the Collaborative Research Centre 512 (Cyclones and the North Atlantic Climate System) funded by the German Science Foundation.

  • The field experiment BASIS 2001 took place in the Gulf of Bothnia of the Baltic Sea. The Finnish Research Vessel Aranda kept a fixed position in the pack ice and was a base for standard meteorological measurements and radiosonde ascents. Surface measurements were also taken at four land stations (Marjaniemi, Oulu, Kuivaniemi, Haparanda). The research aircraft DO-128 of the University Braunschweig performed 10 flight missions. The BASIS experiments as well as ALKOR 2000 and 2001 are part of the research compound BALTIMOS (BALTic sea Integrated MOdel System). BALTIMOS in turn is part of the Baltic Sea Experiment (BALTEX). The overall objective of all eight field experiments (BASIS and ALKOR) was to collect a comprehensive data set suited to validate the coupled model system BALTIMOS for the Baltic Sea region. The observations mainly focus on: - the atmospheric boundary layer structure and processes and the air-sea-ice interaction over areas with inhomogeneous sea ice cover - the atmospheric boundary layer structure over open water under different synoptic conditions such as cold-air advection, warm-air advection or frontal passages. In addition to the published datasets several other measurements were performed during the experiment. Corresonding datasets will be published in the near future and are available on request. Details about all used platforms and sensors and all performed measurements are listed in the fieldreport. The following datasets are available on request: meteorological station Marjaniemi and Oulu airport, ground data at RV Aranda, 10 flights of research aircraft DO-128

  • The field campaign LOFZY 2005 (LOFoten ZYklonen, engl.: Cyclones) was carried out in the frame of Collaborative Research Centre 512, which deals with low-pressure systems (cyclones) and the climate system of the North Atlantic. Cyclones are of special interest due to their influence on the interaction between atmosphere and ocean. Cyclone activity in the northern part of the Atlantic Ocean is notably high and is of particular importance for the entire Atlantic Ocean. An area of maximum precipitation exists in front of the Norwegian Lofoten islands. One aim of the LOFZY field campaign was to clarify the role cyclones play in the interaction of ocean and atmosphere. In order to obtain a comprehensive dataset of cyclone activity and ocean-atmosphere interaction a field experiment was carried out in the Lofoten region during March and April 2005. Employed platforms were the Irish research vessel RV Celtic Explorer which conducted a meteorological (radiosondes, standard parameters, observations) and an oceanographic (CTD) program. The German research aircraft Falcon accomplished eight flight missions (between 4-21 March) to observe synoptic conditions with high spatial and temporal resolution. In addition 23 autonomous marine buoys were deployed in advance of the campaign in the observed area to measure drift, air-temperature and -pressure and water-temperature. In addition to the published datasets several other measurements were performed during the experiment. Corresonding datasets will be published in the near future and are available on request. Details about all used platforms and sensors and all performed measurements are listed in the fieldreport. The following datasets are available on request: ground data at RV Celtic Explorer