Polar regions are data sparse regions. Research ships operating in polar regions often record sea-ice conditions during their transects through ice infested waters. Such observations of the sea-ice conditions are often the only information that can be provided in addition to satellite-based estimates of the sea-ice conditions, such as sea-ice concentration or sea-ice thickness. Such observations have been carried out and gathered using two protocols. For the Antarctic, this is the so-called ASPeCt protocol [Worby and Allison, 1999; Worby and Dirita, 1999; Worby et al., 2008]. For the Arctic, this is the so-called ASSIST/IceWatch protocol [Hutchings et al., 2018]. The latter builds on the ASPeCt protocol, incorporating surface melt conditions being more ubiquitous in the Arctic during summer. Ship-based observations of the sea-ice conditions are conducted manually, visually, i.e. by eye, regularly every hour taking into account an area around the ship of about one kilometer radius. Note that this area distorts to an elliptically shaped area as a function of observers' experience, ships' cruising speed and ice and visibility conditions. Each observation comprises the total sea-ice concentration, and the concentration, level ice thickness, level ice snow depth, fraction and height of ridges, ice type, snow type, and floe size for the up to three thickest ice types. For the Arctic, melt-pond fraction and stage-of-melt are also part of the observables. In addition to the ships' position often auxiliary parameters such as visibility, wind speed and direction, or air and water temperature are recorded. For development and evaluation of satellite-based sea-ice products, such ship-based observations are of great value. Because of this, within the ESA-CCI sea-ice ECV project (ESA-SICCI), phase 2, a standardized data set of such ship-based observations was generated for both polar regions. It comprised data from June 2002 through December 2015. This time period was motivated by the purpose to evaluate sea-ice concentration data retrieved from AMSR-E and AMSR2 brightness temperature measurements which, at the time the project was initiated, were planned to be retrieved until the end of 2015. In this version 2 of this data set the temporal coverage has been extended until the end of 2019. The data set incorporates observational data from various collections, e.g. a part of the original ASPeCt collection [Worby et al., 2008], which ended in May 2005. More information about all data sources is given in the global attributes of the netCDF files and in two separate reference lists. All data have been manually standardized to the same format (i.e., number of decimals, unit), using the same value to describe missing data, using the same temporal ordering, and filling gaps with the respective missing-data value. Double data entries have been removed. Dubious / obviously wrong entries have been set to missing values. The data set is available as two separate netCDF files, one for the Arctic, one for the Antarctic. It is additionally available as two separate ascii-text files under https://icdc.cen.uni-hamburg.de/en/seaiceparameter-shipobs.html , where the netCDF files are available as well. The data set has been successfully used to evaluate sea-ice concentration and thickness products of the ESA-SICCI phase 2 project.

Polar regions are data sparse regions. Research ships operating in polar regions often record sea-ice conditions during their transects through ice infested waters. Such observations of the sea-ice conditions are often the only information that can be provided in addition to satellite-based estimates of the sea-ice conditions, such as sea-ice concentration or sea-ice thickness. Such observations have been carried out and gathered using two protocols. For the Antarctic, this is the so-called ASPeCt protocol [Worby and Allison, 1999; Worby and Dirita, 1999; Worby et al., 2008]. For the Arctic, this is the so-called ASSIST/IceWatch protocol [Hutchings et al., 2018]. The latter builds on the ASPeCt protocol, incorporating surface melt conditions being more ubiquitous in the Arctic. Ship-based observations of the sea-ice conditions are conducted manually, visually, i.e. by eye, regularly every hour taking into account an area around the ship of about one kilometer radius. Note that this area distorts to an elliptically shaped area as a function of observers' experience, ships' cruising speed and ice and visibility conditions. Each observation comprises the total sea-ice concentration, and the concentration, level ice thickness, level ice snow depth, fraction and height of ridges, ice type, snow type, and floe size for the up to three thickest ice types. For the Arctic, melt-pond fraction and stage-of-melt are also part of the observables. In addition to the ships' position often auxiliary parameters such as visibility, wind speed and direction, or air and water temperature are recorded. For development and evaluation of satellite-based sea-ice products, such ship-based observations are of great value. Because of this, within the ESA-CCI sea-ice ECV project (ESA-SICCI), phase 2, a standardized data set of such ship-based observations was generated for both polar regions. It comprises data from June 2002 through December 2015. This time period is motivated by the purpose to evaluate sea-ice concentration data retrieved from AMSR-E and AMSR2 brightness temperature measurements which, at the time the project was initiated, were planned to be retrieved until the end of 2015. The data set incorporates observational data from various collections, e.g. a part of the original ASPeCt collection [Worby et al., 2008], which ended in May 2005. More information about all data sources is given below. All data have been manually standardized to the same format (i.e., number of decimals, unit), using the same value to describe missing data, using the same temporal ordering, and filling gaps with the respective missing-data value. Double data entries have been removed. The data set is split into two ascii text files, one for the Arctic, one for the Antarctic. It has been successfully used to evaluate sea-ice concentration and thickness products of the ESA-SICCI phase 2 project.

Polar regions are data sparse regions. Research ships operating in polar regions often record sea-ice conditions during their transects through ice infested waters. Such observations of the sea-ice conditions are often the only information that can be provided in addition to satellite-based estimates of the sea-ice conditions, such as sea-ice concentration or sea-ice thickness. Such observations have been carried out and gathered using two protocols. For the Antarctic, this is the so-called ASPeCt protocol [Worby and Allison, 1999; Worby and Dirita, 1999; Worby et al., 2008]. For the Arctic, this is the so-called ASSIST/IceWatch protocol [Hutchings et al., 2018]. The latter builds on the ASPeCt protocol, incorporating surface melt conditions being more ubiquitous in the Arctic during summer. Ship-based observations of the sea-ice conditions are conducted manually, visually, i.e. by eye, regularly every hour taking into account an area around the ship of about one kilometer radius. Note that this area distorts to an elliptically shaped area as a function of observers' experience, ships' cruising speed and ice and visibility conditions. Each observation comprises the total sea-ice concentration, and the concentration, level ice thickness, level ice snow depth, fraction and height of ridges, ice type, snow type, and floe size for the up to three thickest ice types. For the Arctic, melt-pond fraction and stage-of-melt are also part of the observables. In addition to the ships' position often auxiliary parameters such as visibility, wind speed and direction, or air and water temperature are recorded. For development and evaluation of satellite-based sea-ice products, such ship-based observations are of great value. Because of this, within the ESA-CCI sea-ice ECV project (ESA-SICCI), phase 2, a standardized data set of such ship-based observations was generated for both polar regions. It comprised data from June 2002 through December 2015. This time period was motivated by the purpose to evaluate sea-ice concentration data retrieved from AMSR-E and AMSR2 brightness temperature measurements which, at the time the project was initiated, were planned to be retrieved until the end of 2015. In this version 2 of this data set the temporal coverage has been extended until the end of 2019. The data set incorporates observational data from various collections, e.g. a part of the original ASPeCt collection [Worby et al., 2008], which ended in May 2005. More information about all data sources is given in the global attributes of the netCDF files and in two separate reference lists. All data have been manually standardized to the same format (i.e., number of decimals, unit), using the same value to describe missing data, using the same temporal ordering, and filling gaps with the respective missing-data value. Double data entries have been removed. Dubious / obviously wrong entries have been set to missing values. The data set is available as two separate netCDF files, one for the Arctic, one for the Antarctic. It is additionally available as two separate ascii-text files under https://icdc.cen.uni-hamburg.de/en/seaiceparameter-shipobs.html , where the netCDF files are available as well. The data set has been successfully used to evaluate sea-ice concentration and thickness products of the ESA-SICCI phase 2 project.

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 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 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.

From 26 March to 22 April 2003, Germany and Finland carried out a joint expedition (ABSIS - Arctic Atmospheric Boundary Layer and Sea Ice Interaction Study) to test and improve the description of the ocean-ice-atmosphere interaction processes. ABSIS was part of the German ACSYS (Arctic Climate System Study) contribution supported by the Ministry of Education and Research and was connected with the RV Polarstern Winter Arctic Polynia Study expedition. The main objectives of ABSIS were to collect data sets to quantify and study: (a) the thermodynamic and dynamic interaction processes at the ice-atmosphere interface and (b) the vertical structure of the atmospheric boundary layer, particularly the Arctic inversion. The latter is a nearly permanent feature over the sea ice. The Arctic inversion is particularly low and strong in winter and effects the exchange between the boundary layer and the free atmosphere as well as the interaction processes at the ice surface. To achieve the above-mentioned objectives various platforms were applied and placed within a 200 km2 area north of Spitsbergen during the expedition period 26 March to 22 April 2003: RV Polarstern and RV Aranda, a research aircraft (Falcon-20 of the German Aerospace Center), 11 automatic ice buoys, and one ice camp station close to RV Polarstern (8-18 April 2003 only). 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 Aranda, ground data at RV Polarstern, ice station near RV Polarstern

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 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 FRAMZY (in German: Framstraßen-Zyklonen; in English: Fram Strait Cyclones) 2002 took place in the Fram Strait region between Greenland and Spitsbergen and between 76-83¿N during the period 25 February to 25 March 2002. It was the second field experiment (following FRAMZY 1999) on cyclones in the Fram Strait and their impact on sea ice. The objectives of FRAMZY 2002 were to sample a data set in order to understand the processes of cyclone generation and sea ice forcing by the cyclones and to estimate the quality of atmospheric models in analysing and forecasting the cyclones and the quality of sea ice models in simulating the cyclone impacts on the sea ice. FRAMZY 2002 also aims to clarify the role of Fram Strait cyclones in the large interannual variations of the North-to-South sea ice transport through the Fram Strait. To reach the objectives measurements were taken simultaneously in the atmosphere and of the sea ice and covered a wide range of scales from the synoptic (cyclone) to the turbulent scale (turbulent fluxes at the air-ice interface). Measurements were taken in-situ by 14 autonomous ARGOS ice buoys, the Finnish Research Vessel Aranda and the German Research Aircraft Falcon and were supplemented by satellite data from NOAA-AVHRR, RADARSAT and DMSP-SSM/I. FRAMZY 2002 was the second 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. 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 Aranda