Gap flows and the stable boundary layer were studied in northwest Greenland during the aircraft-based experiment IKAPOS (Investigation of Katabatic winds and Polynyas during Summer) in June 2010. The measurements were performed using the research aircraft POLAR 5 of Alfred Wegener Institute (AWI, Bremerhaven, Wesche et al. 2016). Besides navigational and basic meteorological instrumentation, the aircraft was equipped with radiation and surface temperature sensors and with a turbulence measurement system. The calibration procedure is described in Drüe and Heinemann (2013). A detailed description of the experimental setup, the flight missions and the aircraft sensors are given in the field phase report (Heinemann et al. 2011) and in Heinemann (2018). The vertical profiles were flown as slantwise aircraft profiles (ascents or descents). The data were measured at a sampling rate of 100 Hz. For the profiles, a more convenient 1 Hz subset was extracted from the 100 Hz data set and turbulent fluctuations are filtered out using a low-pass filter of 0.05 Hz. Four flight missions were flown over the Nares Strait and the North Water (NOW) polynya: 15, 18, 22, and 23 June 2010. The data are consecutive vertical profiles flown along the Nares Strait and across Nares Strait at different positions (see Heinemann et al. 2011) for plots and coordinates of starting points (also included in the data). Data of temperature, potential temperature, specific humidity, wind speed and direction are included in the data set.

Data description:hradh = radar height above ground in m (should be used in general)hgps = gps height in m (should be used when hrad is not available)xkor = horizontal coordinate (distance from start point in km)T = temperature in °CTh = potential temperature in °Cq = specific humidity in g/kgu= wind u-component in m/sv = wind v-component in m/sff = wind speed in m/sdd = wind direction in ° (range -60° to 300°, because winds were generally northerly)dudz = vertical gradient of the u-component in 1/sdvdz = vertical gradient of the v-component in 1/sdthdz = vertical gradient of the potential temperature in K/mRi10m = Gradient Richardson numberRB = Bulk Richardson number with respect to the lowest levelGradients were computed for 10m height differences (5m below 60m)-----The data are consecutive vertical profiles flown between the waypoints. Each profile has a separate header:Number of values of the profile (n)Mean latitude and longitude of the profile (lat, lon)Distance from start point in km for the begin and end of the profile (xa, xe)DateInversion height (ht in m)Height of the wind maximum (hv in m)Maximum wind of the profile (vmax in m/s)Index for ascent (+1) and descent (-1)