## 2 Experiment Description
### Instrumentation
#### 2.1.3 Remote-Sensing  
For observations of the 3D-wind field over our study area, we deployed a scanning wind LIDAR (Leosphere Windcube 100s) on the shoreline (Figure 1). The Windcube 100s is a pulsed wind LIDAR system operating at a wavelength of 1.54 \(\upmu\)m and a pulse energy of about 10 \(\upmu\)J. It has a maximum range for wind measurements of 3.5 km at a range gate resolution of 50 m. The LIDAR was operated in PPI (plan position indicator) mode, i.e., performing azimuth scans over 360\({}^{\circ}\) alternating between two elevation angles of 1\({}^{\circ}\) and 75\({}^{\circ}\). Further details on the chosen settings are summarized in Table 6.  
A vertically-pointing, single-antenna version of the LATAN-3M SODAR system [90] was installed on the sea ice at a distance of about 50 m from the coastline (Figure 1) on 8 February. The SODAR has a frequency-coded sounding signal which allows several measurements per range gate, thus providing higher data availability and quality compared to single-frequency signals. The frequency-coded signal includes eight consecutive 50 ms pulses with frequencies of 3.32, 3.46, 3.58, 3.66, 3.76, 3.9, 4.02 and 4.13 kHz. The vertical measurement range is from 10 m to 340 m, even though the lowest and highest levels typically suffer from poor data availability. At the lowest 3 to 4 levels, the data availability is reduced, since measurements are only based on the first few frequencies as the sampling starts immediately after the transmission of the last frequency. On the other hand, the data availability from  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Value (Low-Elevation Scan)** & **Value (High-Elevation Scan)** \\ \hline Elevation angle & \(1^{\circ}\) & 75\({}^{\circ}\) \\ Mode & PPI & PPI \\ Minimum range & 50 m & 50 m \\ Maximum range & 3300 m & 3300 m \\ Display resolution & 25 m & 25 m \\ Number of range gates & 131 & 131 \\ Starting azimuth angle & \(0^{\circ}\) & \(0^{\circ}\) \\ Final azimuth angle & 359.9\({}^{\circ}\) & 359.9\({}^{\circ}\) \\ Scan duration & 120 s & 72 s \\ Accumulation time & 0.5 s & 0.5 s \\ \hline \hline \end{tabular}
\end{table}
Table 6: Settings for the alternating PPI (plan position indicator) modes for the operation of the Windcube 100s scanning LIDAR (Light Detection and Ranging).  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Sensor** & **Acq. Frequency** \\ \hline Temperature, _T;_ relative humidity, \(RH\) & HYT 271 & 10 Hz \\ Temperature, _T;_ relative humidity, \(RH\) & P14 Rapid & 10 Hz \\ Temperature, \(T\) & K-type thermocouple & 10 Hz \\ Pressure, \(p\) & BMP 180 & 10 Hz \\ Infra-red temperature, \(T_{IR}\) & MLY90614 & 10 Hz \\ Position, \(lat,lon,alt\) & \(\upmu\)Blox GNSS & 5 Hz \\ Attitude angle \(\theta,\phi,\psi\) & autopilot IMU & 5 Hz \\ \hline \hline \end{tabular}
\end{table}
Table 5: Specifications of the sensors mounted on the Advanced Mission and Operation Research (AMOR) UAV.  
the upper levels is often limited by atmospheric conditions because of the lack of thermal turbulence from which the acoustic echoes originate. The measured parameters are the intensity within the main spectral peak of the return signal and the adjacent band and the Doppler shift of the peak, expressed in terms of radial velocity. The parameters are estimated for each range gate with 3 s-resolution (0.33 Hz). From the data, it is possible to derive, for example, profiles of mean vertical velocity and its variance. Previously, this SODAR has been used to detect wind shear driven turbulence, convective turbulence, strong katabatic flows, and moist air advection with wave structures in the stably stratified ABL [91].