A Shipboard Atmospheric Surface Layer Profiling System for Air-Sea Interaction and Fog Studies

Ship-based measurements for data collection to address fundamental questions in air-sea interaction and/or maritime fog formation suffer from two major obstacles, one is the flow distortion over the deck of the ship, the other is the limitation of the sampling altitude above the ship deck, which is normally a few to tens of meters above the waterline. We have designed a ship-crane based sampling package, the Crane-mounted Cloud and Aerosol Measurement System (C-CAMS), to mitigate both shortcomings of ship-based measurements. The ship crane allows the profiling measurements to extend away from the ship’s hull to minimize potential flow distortion and the thermal impact of the ship deck. Meanwhile, the crane supports the vertical variation of the sampling package to provide the profiling capability from close to the surface to above 10 m depending on the arm length of the crane.

The major design requirement of the C-CAMS is to provide a platform to safely mount research-grade sensor payloads with larger size, weight, and power (SWaP) on a crane wire. C-CAMS platform is a fiberglass pallet container rated to be lifted by a crane and is reinforced to mount a horizontal 10-ft tower section to extend meteorological instrumentation from the body. The sensor suite on the C-CAMS obtains quantities of 3-dimensional perturbations of the wind components, temperature, and humidity (atmospheric turbulent fluxes of momentum, sensible and latent heat), SST, radiative fluxes, and surface height. The instruments are further coupled with fog and aerosol sensors, a water droplet size spectrometer, aerosol size spectrometer, nephelometer, and condensation particle counter that were installed inside with an external intake to draw in ambient air.

In support of Fog and Turbulence in the Marine Atmosphere (FATIMA) field campaigns, the C-CAMS was first deployed on the R/V Atlantic Condor during the FATIMA Grand Banks field campaign in 2022. It was further deployed on the R/V Onnuri during the FATIMA Yellow Sea field campaign in the summer of 2023. In this presentation, we will give an overview of the C-CAMS, including its platform and measurement capabilities. Results from the FATIMA Grand Banks will be shown to demonstrate its performance and a comparison with results from the bow masts systems will be made.