This dataset contains ice motion observations made under the Australian Antarctic Program, Projects 4593 and 4506. Data was obtained using two Spotter wave buoys (Sofar Ocean Technologies), hereafter wave buoys, and two open-source ice motion loggers, hereafter ice buoys. Instruments were deployed on (land)fast ice on the eastern rim of the Amery Ice Shelf, Antarctica (69.2 degr. S, 76.3 degr. E), on 7 December 2019. After the break-up of the ice occurring at the start of January 2020, instrumentation started to drift with the ice. Last transmission recorded was on 10 March 2020. The wave buoys measure their 3-axis motion at 2.5 Hz through GPS and have an accuracy of approximately 2 cm for the recorded significant wave height. The ice buoys measure motion in 9-degrees-of-freedom at 10Hz using a VectorNAV VN-100 IMU, with an accuracy of O(mm) for short waves and O(cm) for long waves. Both instruments also record their geographical location through GPS. Full time series of their motion is processed on board and summaries are send through Iridium. For the ice buoy wave spectra were transmitted roughly every 3 hours. The transmission interval for the wave boys was variable, ranging from every half an hour to every 3 hours. Data transmitted by the wave buoys was either integral wave properties or the complete wave spectrum. In the dataset, WB and IB are abbreviations for wave buoy and ice buoy, respectively. This dataset includes all observations transmitted during the measurement campaign (WB1, WB2, IB1, IB2). E = wave energy spectrum (m2/s); f = wave frequency (Hz); a1, a2, b1, b2 = Fourier coefficients; Hs = significant wave height (m); Tp = peak period (s); Tm01 = mean period (s); Dir_peak/mean = peak and mean wave direction and 'spr' refers to spreading; volt = battery voltage (V). Time is in UTC, and in Matlab’s datenum format (i.e. the number of days since year 0000). The geographical coordinates ‘lat’ and ‘lon’ (latitude and longitude, respectively) are in degrees. Note, as the ice buoys transmit the GPS coordinates and wave data in separate data messages, for the ice buoys ‘time’ refers to the reference time of the wave properties Hs and Tp, whereas ‘GPStime’ refers to the reference time of the geographical coordinates (lat and lon). For the wave buoy, all data is transmitted at the same time.

A Langrangian free drift model is developed, including a term for geostrophic currents that reproduces the 13 h period signature in the ice motion observed in the data (CLSC_WIIOS_2017; parent data). The calibrated model is shown to provide accurate predictions of the ice drift for up to 2 days, and the calibrated parameters provide estimates of wind and ocean drag for pancake floes under storm conditions. Model setup is described in "Drift of pancake ice floes in the winter Antarctic marginal ice zone during polar cyclones", Alberello et. al [https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019JC015418; pre-print https://arxiv.org/pdf/1906.10839.pdf]. The dataset includes model data. Six model outputs are included. (i) "full_t00" includes the full 10 days simulation, with all the forcing switched on (ii) "noge_t00" includes the full 10 days simulation, but the geostrophic current is suppressed (iii) "full_t25_noup" includes the simulation with start at 2.5 days, all the forcing switched on, no update of the drag coefficients (iv) "full_t25_newn" includes the simulation with start at 2.5 days, all the forcing switched on, the drag coefficients are recalibrated (v) "full_t50_noup" includes the simulation with start at 5 days, all the forcing switched on, no update of the drag coefficients (vi) "full_t50_newn" includes the simulation with start at 5 days, all the forcing switched on, the drag coefficients are recalibrated In each file: - rho_a the air density (1.3 kg/m3) - rho_w the water density (1028 kg/m3) - rho_i the ice density (910kg/m3) - C_w the water drag coefficient (calibrated) - C_a the air drag coefficient (calibrated) - turn the turning angle (25 degrees) - Nansen the Nansen number evaluated using C_a and C_w - aalpha a model parameter (proportional to air and ice parameters) - abeta a model parameter (proportional to water and ice parameters) - ag amplitude of the geostrophic current (U_g=0.125m/s) - tg initial phase of the geostrophic current (in radians) - to start time (in matlab format, use "datestr(to)" ), after which model resolution is 60 seconds - wo components of wind in the East and North direction (m/s) - wi components of wind in the East and North direction (m/s) - uo components of modelled ice drift speed in the East and North direction (m/s) - lo longitude and latitude of modelled ice position (degrees) - xo position of modelled ice in the East and North direction (m), given with respect to the initial position (0,0) - wco components in the East and North direction of geostrophic current (m/s)