Turbulence Measurements Aboard Waveglider during CASPER-West

During the Coupled Air Sea Processes and Electromagnetic ducting Research east coast field campaign (CASPER-East), the NPS-owned Liquid Robotics WaveGlider SV2 (previously Mako, now named Thresher) was instrumented with turbulence and mean meteorological sensors. While Thresher demonstrated its capability as a robust, autonomous sensor housing platform, data collected from Thresher in CASPER-East were limited due to water ingress and salt corrosion inside the meteorological sensors and data acquisition system. The sensor payload configuration for Thresher was redesigned for the CASPER west coast field campaign to ensure continuous data collection during its deployment, while maintaining minimal flow distortions. CASPER-West took place in the Southern California Bight region from 27 September to 26 October, 2017. Thresher was deployed on 4 October from the R/V Sally Ride, repeating a 10-km east-west oval track approximately 42-km south of Pt. Mugu, CA for 15 days of continued measurements. During this period, Thresher experienced light to moderate wind (3 m/s and 9.5 m/s for mean and maximum wind speeds) and calm sea (0.916 m and 1.5 m mean and maximum significant wave height) conditions.

The major sensor improvement for Thresher in CASPER-West was utilizing a more rugged, stainless-steel bodied 3-D sonic anemometer (Gill WindMaster Pro). The anemometer sensing head extended nominally 0.9 meters above the waterline and was mounted midsection of the float. A separate 1-meter mast was deployed aft and instrumented with a profile of three temperature and relative humidity sensors (Rotronic HC2-S3) and one multi-parameter weather sensor (Vaisala WXT520) above. This is the first time concurrent turbulence and multiple level mean wind and thermodynamic quantities were sampled at such a low level near the sea surface in minimally disturbed environment for an extended period of time. This dataset will be explored extensively to evaluate the marine atmospheric surface layer flux-profile relationship. R/P FLIP was concurrently moored 7-km east of the Thresher track and conducted similar turbulence measurements at a fixed location. Τhe Thresher mean and flux quantities can be used to compare the lowest mast levels from R/P FLIP, which will be examined in this study.