A COTS Radar Profiler for Cruise Ships

Recently, a Commercial-Off-The-Shelf (COTS) radar wind profiler system has been adapted by URS Meteorological Systems and the University of Miami for operation on the upper-deck structure of a commercial cruise ship. The first test of this concept was aboard the Royal Caribbean Cruise Lines (RCCL) Explorer of the Seas.

The COTS profiler is part of a suite of atmospheric and oceanographic remote sensing and in-situ instruments that the University of Miami (UM) Rosenstiel School has developed in collaboration with RCCL and NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) with additional funding from the National Science Foundation. The state-of-the-art shipboard laboratories and instrumentation that have been developed for the Explorer provide a unique platform for atmospheric and oceanographic observations on weekly cruises though the Caribbean.

The best physical placement for a radar profiler antenna on a ship is on one of the upper decks, clear of as much of the superstructure as possible. A major concern for these installations is direct and reflected radio frequency energy that results in sea clutter echoes from ocean waves. For this installation, the agreement between UM and RCCL allowed a modified opening to be constructed in the Explorer’s Deck 13 to partially house the radar antenna. We made the assumption that for initial testing and data requirements we would utilize a simple two-beam antenna that steered oblique beams toward the ship’s bow, away from the superstructure, and at a 90 degree angle relative to the bow and the ships motion. We also assumed that for a large stabilized cruise ship, the pitch, role and yaw components of motion could be largely ignored, and the only compensation required would be the ship’s motion relative to the horizontal wind components. The Explorer’s inertial navigation system provides heading and speed information for the simple motion compensation. These assumptions allowed a COTS profiler to be used in this operational data collection system.

The profiler selected for this application was a commercial LAP-3000 boundary layer profiler. The LAP-3000 utilizes modular software called LAP-XM that allows the user to select and interact with a variety of data products. Because of the concern with sea clutter, we used an experimental version of LAP-XM using wavelet processing to resolve the clear-air spectral peaks in the presence of large sea-clutter peaks. We also used an off-line processor to implement ship’s motion compensation.

This paper describes the installation and testing of the COTS profiler on the Explorer of the Seas, and shows results of the initial data collection campaigns. We also describe expansions of this program that may occur in the future.

References:

1. Jordan, J.R. et. Al. 1997: Removing ground cluttere and intermittent clutter contamination form wind profiler signals using wavelet transforms. J. Atmos. Oceanic Tech., 14, 1280-1297.

2. Jordan, J.R. et. Al. 1998: Motion compensation for buoy mounted wind profiling radars, Fourth International Symposium on Tropospheric Profiling, Snowmass, CO. Sept. 21-25, 1998, 155-157.