Development and Deployment of the Surface Current Imaging Nowcast System

Abstract

This paper describes the development and installation of an ocean surface current monitoring device called SCINS: Surface Current Imaging Nowcast System. We describe the process of designing and building the prototype system, installation on an offshore platform, implementation of real-time reporting, and results from one year of operations. SCINS utilizes passive long-wave infrared imaging of the ocean to derive surface currents. This is done using a time-series of images to observe the phase-speed of the ocean waves. Then, the Doppler shift of the observed waves due to the surface current is determined using a non-linear least squares fit. The primary components of SCINS are a long-wave infrared camera and a data acquisition computer. The camera is mounted several 10s of m above the water surface. The system collects imagery at 2 Hz for 5 minutes every 15 minutes, day and night, and calculates surface currents in real-time. In this paper, we describe the results from deploying SCINS on an offshore platform, Chevron's Big Foot TLP, in the Gulf of Mexico for one year of continuous data collections, including several tropical storm and hurricane events. Results are compared to environmental data to describe system performance as a function of wind, wave, and sea conditions. We describe the engineering challenges and lessons learned from designing and installing this new type of passive imaging system for offshore use. We conclude that SCINS is an effective method for measuring surface currents in the vicinity of offshore platforms, requiring very little maintenance and without the need to put any instrumentation in the water.