Airborne and dropsonde measurements in MCAOs during STABLE in March 2013

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.