No abstract

Continuous sea level measurements have been made and recorded for more than 100 years, but their importance has increased dramatically in the past few years due to the great international interest for monitoring global levels in anticipation of climate warming. Since the National Ocean Service (NOS) is the primary agency for measuring and recording water levels in the United States, it is being encouraged to increase the number of permanent sea level measuring stations especially in the polar regions where the data are extremely sparse. Personnel from the Physical Oceanography Division (POD) and the Ocean Systems Division (OSD) of the Office of Oceanography and Marine Assessment (OOMA) have been researching the status of the technology and the requirements for water level measurements in the polar regions with special emphasis on the needs of NOAA's Climate and Global Change Program and The Global Sea Level Observing System, known as GLOSS. It is called GLOSS because it measures the global level of the sea surface, a smooth level after averaging out waves, tides and meteorological events. GLOSS, coordinated by the Intergovernmental Oceanographic Commission (IOC), provides high quality standarized data from which valuable sea level products are prepared for international and regional research programs as well as for practical national applications. This report includes a survey of the work that NOS and others are or have been doing in this area and also assesses the state-of-the-art of the technology involved, the potential for future development, and provides recommendations for near and long-term projects. The report concludes that the technology and techniques exist for making sea level measurements in polar regions but that they must be site-specific; also, that stable bench mark connections and atmospheric pressure measurements are mandatory; that the field measurement system should be as automated as possible; and that near real-time transmission of data is highly desirable to ensure proper system operation and early availability of information to users. The report recommends the use of thermal bench marks in certain polar areas and the further development of acoustic and electromagnetic means of transmitting data from underwater sensors through the ice or land to nearby shore stations. It also recommends that Prudhoe Bay, AK be established as a pilot station for further investigations into the measurement requirements of other Arctic stations and that a cooperative program be initiated with the National Science Foundation for establishing stations in Antarctica.

The National Ocean Service (NOS), w i t h i n t h e National Oceanic and Atmospheric Administrat i o n (NOAA), operates and maintains a National Water Level Observation Network (NWLON) t o a c c o m p l i s h i t s s t a t u t o r y r e s p o n s i b i l i t y f o r measuring, collecting, analyzing, and dissemin a t i n g w a t e r l e v e l d a t a . Because the equipment used t o s u p p o r t t h e NWLON i s aging and