Autonomous Wave Glider – New Type of Measurement Platform for Air-Sea Interaction Research

In support of the Coupled Air Sea Processes and Electromagnetic ducting Research East (CASPER-EAST) field campaign, a Liquid Robotics Inc. (LRI) Wave Glider (model SV2), also known as the Sensor Hosting Autonomous Remote Craft (SHARC), was deployed off the coast of Duck, NC in October/November 2015 to measure meteorological and oceanographic parameters near the air-sea interface. The LRI SHARC is an autonomous ocean-surface vehicle propelled only by wave motion. The standard LRI METOC-version SHARC hosts only a 1-meter meteorological mast instrumented with an all-in-one sensor package, the AirMar PB200. The system outputs 10-minute averaged air pressure, temperature, and wind speed and direction. In a previous effort to evaluate the AirMar PB200, an independent mast was developed to mimic the AirMar PB200 with trusted, research-quality instruments, as well as to add relative humidity, solar radiation, water temperature, and surface wave measurements.  Due to its small footprint, compared to a ship or vessel, the SHARC could potentially sample in relatively undisturbed air and provide quality turbulence measurements, enhancing its capability for air-sea interaction studies. In this effort, a fast-response 3-D sonic anemometer at 1-meter and an inertial measurement unit were added to sample turbulence and virtual temperature perturbations so momentum and sensible heat fluxes can be calculated using the eddy-correlation method. During CASPER-EAST, NPS SHARC Mako was deployed several times and followed a 9 km long oval track traveling at an average speed of approximately 0.8 m s^-1. During favorable sea conditions, the NPS Marine Air-Sea Flux (MASFlux) 3-meter spar buoy was tethered to a nearby moored float, providing comparison and validation data for the SHARC turbulence suite. Initial analyses and comparisons of mean and flux data will be presented, primarily focusing when both platforms were collocated and measuring continuously.  Although the SHARC turbulence suite was close to the water line, temporal variations of the mean and fluxes and power spectra of turbulence from both MASFlux and SHARC sensor package agree well in moderate wind conditions. From this validation, the LRI SHARC demonstrated it is a viable, robust, autonomous platform for measuring mean and flux parameters.