Airborne Remote Sensing of Surface and Internal Wave Processes
On the Inner Shelf
To understand the role of surface and internal waves on inner shelf kinematics (mixing) and dynamics.
OBJECTIVES The primary objectives of this proposal are to investigate the role of surface and internal wave processes on the dynamics, transport and mixing in the water column on the inner shelf and their measurement using airborne and autonomous surface platforms.
April 20 2015 - Kick-off meeting powerpoint presentation, Naval Postgraduate School (NPS), Monterey, CA Download PDF file. (4.6MB)
APPROACH The approach has been to fly the Modular Aerial Sensing System (MASS, Melville et al. 2015) on a light twin aircraft (Partenavian P68) and a helicopter (Bell 206 L-III) (Figure 1) over the inner shelf using the components of the MASS system, including a waveform scanning lidar, visible and infrared (IR) and hyperspectral imagers, and a high precision GPS/IMU unit to measure surface waves, surface wave breaking,currents, surface-flow divergence and vorticity, SST, and SST signatures of internal waves (IWs). These data can be used to track the evolution of surface waves and the surface signatures of internal waves from offshore sources across the shelf until they are reflected or dissipated in the inner shelf. The data can also be used to measure along-shore currents and near-shopre vorticity associated with surface and internal wave shoaling.
Figure 1. The MASS system on the bench at the Air-Sea Interaction Laboratory, SIO. It is flown on the Partenavia P68 light twin-engined aircraft and the Bell 206 L-III helicopter.
Key individuals are: Luc Lenain (Principal Development Engineer) and Nicholas Statom (Associate Development Engineer) who designed and built the MASS and serve as observer and operator for the system in flight.
Figure 2. Aerial views of Pt Sal. Note the foamy front extending from Pt Sal in the top left image. This was a common flow feature emanating from Pt Sal and other headlands (see bottom right image).
WORKCOMPLETED From June 24-July 2, 20215, seven fixed-wing (Partenavia) flights of the MASS were made during the Inner-Shelf Pilot Experiment in the area of Pt Sal, California. Figure 2 shows photos of the Pt Sal area. The flights lasted from 1.5 – 5 hours at approximately 100 kts and their positions on time series of winds, significant wave height, Hs, and tides from NDBC buoy 46011 are shown in Figure 3 .
Figure 3. Timing of seven fixed-wind flights relative to tides, wind speed and significant wave height at NDBC buoy 460011 located SSW of Pt Sal.
Note that in addition to timing flights for high and low tide, they were also timed for maximum ebb and flow of the tide, corresponding to maximum tidal currents in the area.
Figure 4. IR and visible imagery of the foam and colder surface waters assocxiated with the flow around Pt Sal.