International Arctic Buoy Programme D Dataset [2013-2016]: gridded sea ice velocity fields from buoys

This data set contains 12-hourly interpolated surface velocity data from buoys.
Point grid: Latitude 74N to 90N - 4 degree increment Longitude 0E to 320E - 20 and 40 degree increment. Note about derivative directions:
The velocities and their derivatives are expressed with respect to a cartesian coordinate system.
With the origin at the North Pole, the x axis coincides with the Greenwich Meridian, and the y-axis with the 90E Meridian.
The cartesion grid is a Polar Stereo projection of lat, lon onto an x,y grid in kilometers