Results from NOAA's test and evaluation of microwave radar water level sensors and plans for a transition to operational applications

The United States National Oceanic and Atmospheric Administration (NOAA) Center for Operational Oceanographic Products and Services (CO-OPS) is responsible for developing and maintaining the National Water Level Observation Network (NWLON), which consists of over 200 long-term observatories located across U.S. coasts, including the Great Lakes and U. S. island territories. CO-OPS continues to analyze state-of-the-art and emerging technologies to identify potential improvements in data quality and operating efficiency and to maintain core expertise for authorized missions. The international ocean observing community has recognized that microwave radar range sensors offer many potential benefits for long-term sea level monitoring. The most notable advantage of such sensors is the ability to measure water level remotely and from above the sea surface. Over the past 3.5 years, CO-OPS has conducted a series of extensive laboratory and long-term field tests with several different microwave radar range sensors to determine their suitability for use as water level sensors in NWLON and other CO-OPS measurements systems. Intermediate results from CO-OPS' extensive test efforts have been previously reported at various conferences and through several reports over the last three years. This paper provides a summary update on field test analysis conducted to date and reports a significant milestone to which most recent results have led: CO-OPS has recommended limited acceptance of radar water level sensors for use in its network of coastal observatories, and a transition of the new technology to operational applications is currently underway. In addition to a summary of most recent field test results, highlights from CO-OPS' plan to transition the microwave radar water level sensors to its network of operational coastal observatories will be presented, along with progress on initial operational installations. A summary of continued field testing to better understand microwave radar sensor performance capability and limitations in open ocean, large wave environments will also be presented.