Airborne Remote Sensing for the ONR Sea State DRI Experiment

As part of the Office of Naval Research Sea State Departmental Research Initiative, researchers aboard the R/V Sikuliaq will be conducting a broad series of measurements to investigate the processes governing the interaction of the ocean waves with the formation and evolution of the floating sea ice and ocean/ice boundary layers of the Arctic ice pack during the seasonal southward advance of the ice in October 2015. The DRI will also support a series of research flights by the Naval Research Laboratory to measure and characterize the ocean waves and sea ice distribution in a larger region surrounding the ship. A Twin Otter aircraft will be equipped with Multi-Band SAR, scanning lidar, digital photogrammetric system, atmospheric pressure sensor, and KT-19 radiometer. The SAR is a software programmable radar transmitter/receiver with fully polarimetric bandwidth of 215-915 MHz (P-band) and 1000-1500 MHz (L-band). One of the strengths of the airborne SAR compared to satellite systems is the ability to fly an arbitrary trajectory, e.g. linear tracks or boxes/circles around a region. Low frequencies and large bandwidth of the system result in high resolution images of the ice in a part of the spectrum complementary to satellite SARs. The fully polarimetric SAR is also sensitive to different features in HH, VV and the cross polarizations, including the variation of such returns for a given ice area as a function of illumination direction. The SAR, lidar, camera and radiometer maps will allow the discrimination between open water, thinly frozen-over leads, and substantial ice floes. Maps will be analyzed for floe size distributions and a regional estimate of the radiative heat transfer. The lidar will map the ocean wave heights and be used to produce wave height spectra and wave train directional information. After initial reduction, the airborne data will be integrated with the in-situ shipboard and satellite data.