Description: The data set basically contains airborne and dropsonde measurements of the AWI-campaign “SpringTime Atmospheric Boundary Layer Experiment (STABLE) that were performed using the POLAR 5 research aircraft to observe the vertical structure of the lower troposphere and boundary layer modifications during marine cold-air outbreaks (MCAOs). Such MCAOs are typically characterized by advection of very cold air masses originating from the sea ice covered ocean over a relatively warm water surface and are thus often associated with strong atmospheric convection. In this data set, meteorological measurements from four days (4, 6, 7, and 26 March 2013) are included, all performed over the marginal sea ice zone and over the open ocean in the Fram Strait region north and west of Svalbard. All research flights of 5-6 hours duration started and ended at Longyearbyen airport, and the measurements provided here were conducted during aircraft vertical profiles and by dropsondes. The observations covered an area between about 78-85° N latitude and -5°-20° E longitude. Both airborne and dropsonde data sets consist of highly-resolved measurements of pressure, temperature, humidity, and wind (for the airborne data only the horizontal wind). The airborne measurements were obtained by instruments installed in and at a turbulence nose-boom with a sampling rate of 100 Hz (pressure, temperature, wind) or 1 Hz (humidity). Pressure and wind components were measured with a five hole probe, temperature with a Pt100 resistance thermometer, and relative humidity with a dew point mirror. Global Position System (GPS) and Inertial Navigation System (INS) were used to derive height and position of the aircraft, where besides the GPS altitude also the more reliable pressure-based altitude is provided. The airborne data were adjusted to the time measured at the nose-boom and quality-controlled. All airborne measurements are provided with 100 Hz. Dropsonde measurements were performed with Vaisala RD93 sondes (Vaisala, 2003; Ikonen 2010) equipped with temperature, pressure and humidity sensors, which operated at 2 Hz recording frequency. Wind, position, altitude, and the sonde's fall rate were derived via the GPS module with a recording frequency of 4 Hz. All dropsonde data were quality-processed using the Atmospheric Sounding Processing ENvironment software (ASPEN, version 3.4.6, see Martin & Suhr, 2021). The data set is a supplement to Michaelis et al. (in review), who provide a much more detailed description on measurement accurracies, the individual quality-processing mechanisms, and on the quality of the data. They also give a brief overview on the characteristics of the MCAOs based on the quality-processed data. In addition, Tetzlaff et al. (2014) and Tetzlaff (2016) performed several analyses of the observed MCAOs based on this data, but without using ASPEN for the quality-processing of the dropsonde data. Differences are also explained in Michaelis et al. (in prep.). Finally, Hartmann et al. (2018) provide more details on the quality of the airborne measurements including the determination of related measurement accurracies.

Description: This data set consists of the airborne measurements obtained in the framework of the AWI-campaign "SpringTime Atmospheric Boundary Layer Experiment" (STABLE) that are used as supplement for the study by Michaelis et al. (2020). The measurements were performed in the atmospheric boundary layer near three different leads in the Arctic Marginal Sea Ice Zone north and northwest of Svalbard on 10, 25 and 26 March 2013. All cases represent conditions of a nearly lead-perpendicular convective flow over the leads. For each of the three cases, different flight legs are provided (see filenames): (a) 'upwind': a vertical profile performed upwind of the lead (b) 'cross-lead': a low-level horizontal flight leg performed across the lead along the mean wind direction (c) 'lead-parallel': lead-parallel flight legs performed at different distances to the upwind lead edge at different altitudes, either above the lead or further downwind (d) 'saw-tooth': a saw-tooth flight pattern performed across the lead along the mean wind direction (only for 25 March) (e) 'lead-parallel_avg-val_fluxes': flight-leg-averaged values of mean atmospheric quantities and turbulent fluxes for the lead-parallel legs The measurements of wind, temperature, pressure and humidity were performed with instruments mounted on a 3m long nose-boom of the research aircraft Polar 5 (see also Tetzlaff et al., 2015). For the three wind components, temperature, and pressure, the sampling rate is 100Hz so that with the observed ground speed of the aircraft of 40 to 75 ms-1 a spatial resolution of approximately 0.4 to 0.75m was obtained (Tetzlaff et al., 2015, Michaelis et al., 2020). The three wind components and air pressure were measured using a five hole probe. Air temperature was measured with a PT-100 resistance thermometer. Relative air humidity was measured with a dew point mirror. Global Position System (GPS) and Inertial Navigation System (INS) were used to derive height and position of the aircraft. In addition, a KT-19 radiation thermometer and an infrared (IR) scanner were used to measure surface temperatures. All data is adjusted to the time measured at the nose-boom. The turbulent fluxes were calculated using the eddy covariance method for all lead-parallel flight legs (see Tetzlaff et al., 2015, Michaelis et al., 2020). Mean values averaged over an entire flight leg and the corresponding statistical error are provided for air temperature, air density, horizontal wind speed, the sensible heat flux, the absolute value of the total vertical flux of horizontal momentum, and for the x- and y-components of the latter quantity. A more detailed description on the measurement techniques and flight patterns is provided by Tetzlaff et al. (2015). For more details on the post-processing of the raw data and on measurement accuracy, see Hartmann et al. (2018).

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water. On all three days, the corresponding flight patterns mainly consisted of vertical aircraft profiles between 30m and 1000-1500m height during saw-tooth patterns and of low- and high-level horizontal flight legs from the marginal ice zone towards the fjord and vice versa. Each file consists of measurements from one flight leg, where in each file name we include start and end time (in UTC) and the following abbreviations: • h: low-level horizontal flight leg (below 1000m flight altitude) • H: high-level horizontal flight leg (above 1000m flight altitude) • t: ascent or descent with an altitude difference 〈1500m • T: ascent or descent with an altitude difference 〉1500m (or ascent/descent at high altitudes) The airborne measurements were obtained by instruments installed in and at a turbulence nose-boom. The following variables are included in the data set (see Table 1): air pressure (static & dynamic) and wind obtained from a Rosemount 858 five-hole probe as well as temperature (Pt100 resistance thermometer), all with 100 Hz sampling rate, relative humidity (Vaisala HUMICAP in a Rosemount housing, 1Hz), radar altimeter (1Hz), and surface temperature (KT-19 radiation thermometer, 10Hz). Global Position System (GPS) and Inertial Navigation System (INS) were used to derive the aircraft's height, velocity, and position, and also for the calculation of the three wind components. Besides the GPS-based height, we provide also the more reliable pressure-based altitude. All variables are provided with 100Hz in each file. Air pressure and air temperature data were corrected as described in detail by Michaelis et al. (2022). Relative humidity data were corrected for adiabatic heating, which occurs due to compression of the air entering the Vaisala HUMICAP sensor situated in the Rosemount housing (see Smit et al., 2013). More detailed description on the measurements including the instruments' accuracies and the quality-processing of the measurements is provided by Suomi et al. (2023), for which this data set is a supplement, as well as by Michaelis et al. (2021, 2022) and Tetzlaff et al. (2014, 2015). In the latter four publications, data from the STABLE campaign is used as well but mainly from flight days other than in this data set. The corresponding data are available at Lüpkes et al. (2021a, b). Master tracks for all STABLE research flights can be found at Steinhage (2015). Finally, Hartmann et al. (2018) provide more details on the quality of such airborne measurements in general including instrument calibrations and the determination of related measurement accuracies. Note that for the wind measurements the full accuracy is only achieved and the estimates on uncertainty are only valid for straight level flight sections (Hartmann et al., 2018).

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.

Description: The data set consists of high resolution airborne measurements that were obtained mainly over Svalbard and near the sea ice edge north of Svalbard on three days in March 2013 during the campaign "SpringTime Atmospheric Boundary Layer Experiment (STABLE). STABLE was led by the Alfred Wegener Institue (AWI) and by the Finnish Meteorological Institute (FMI). The measurements were performed using the POLAR 5 research aircraft, where all research flights of 5-6 hours duration started and ended at Longyearbyen airport. During STABLE, observations focused on the vertical structure of the lower troposphere as well as boundary layer modifications, e.g. during marine cold-air outbreaks and by convection over leads in sea ice. The data set presented here predominantly consists of measurements that were obtained over the Wijdefjorden, which is a North-South oriented fjord with a length of more than 100km in the northern part of Spitsbergen. The measurements were carried out to study the boundary layer structure in the fjord as well as for analyses of the role of the topography on the atmospheric conditions. In its southern part, the fjord was covered by land-fast sea ice until about 72.5km north of the fjord's head. In its northern part, there was open water.