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Platforms of the National Data Buoy Center provide vital meteorological and oceanographic observations from data-sparse marine areas worldwide. The data are essential for real-time weather forecasting and research programs. This paper provides information on the data-acquisition systems, networks, monitoring capabilities, data processing and dissemination, data quality and availability, and related technology development for these platforms.

This paper presents a case study on the wave-current interaction near the local curvature of a Gulf Stream meander. The wave data were obtained from in situ measurements by a pitch-roll discus buoy during the Surface Wave Dynamics Experiment (SWA-DE) conducted off Wallops Island, Virginia, from October 1990 to March 1991. Owing to the advection of the Gulf Stream by the semidiurnal tide, the discus buoy was alternately located outside and inside the Gulf Stream. The directional wave measurements from the buoy show the changes in wave direction, wave energy, and directional spreading when waves encountered the current in the Gulf Stream meanders. A wave refraction model, using the ray-tracing method with an estimated Gulf Stream velocity field and meandering condition, was used to simulate wave refraction patterns and to estimate wave parameters at relative locations corresponding to buoy measurements. The numerical simulation shows that a focusing zone of wave rays was formed near the boundary and behind the crest of a simulated Gulf Stream meander. The focusing of wave rays causes changes in wave direction, increases in wave energy, and decreases in wave directional spreading, which are in good agreement with the results from the buoy measurements. 1. Introduction When a surface wave train encounters a variable current, an interchange of momentum and energy occurs which can be quite strong. The wave refraction by the shear current at an oceanic from can significantly change wave direction, wavelength, and wave energy [Johnson, 1947; Kenyon, 1971]. Recently, Irvine [1987] showed that the effect of the current meandering, or the local curvature of the current, can further complicate the wave refraction pattern. Mapp et al. [1985], Irvine [1987], and Irvine and Tilley [1988] suggested that unexpected giant waves [Draper, 1964; Schumann, 1976] are caused by local focusing of swell refraction in a meandering oceanic from. Liu et al. [1989] presented a case study of wave-current interaction near an oceanic front, which examined the effects of meandering on waves propagating across the frontal current using directional wave data obtained by NASA airborne radar and numerical model simulations. Most previous studies on wave-current interaction in an oceanic from relied on numerical model simulations with limited field measurements that were obtained mainly by means of remote sensing [Hayes, 1980; McClain et al.McLeish and Ross, 1985; Mathiesen, 1987; Holthuijsen and Tolman, 1991]. Sheres et al. [1985, 1987] inferred the strength of a linear shear feature in a coastal current system on the basis of wave refraction observed in aerial photo-Weller, R.A., M. A. Donelan, M. G. Briseoe, and N. E. Huang, Riding the crest: A tale of two wave experiments, Bull.

The National Oceanic and Atmospheric Administration (NOAA) operates a network of automated moored buoys in the oceans whose installation began in the early 1970s. What began as a research and development program consolidating independent U.S. buoy projects, by the mid-1980s evolved into an operational activity when the National Data Buoy Center (NDBC) was moved into NOAA's National Weather Service (NWS). Except for a few reimbursable projects requiring ocean data, little effort was placed on sustained ocean monitoring, as NDBC focused upon satisfying NWS' mission requirements. NOAA's recent direction to become a “matrix” organization is leading to greater utilization of assets across its line offices. NDBC and its Marine Observing Network (MON) of moored buoys and fixed stations have become recognized as NOAA assets that can help meet NOAA-wide strategic goals. This paper describes some of NDBC's history and the future role it can play as part of a federal “backbone” system to support scientific needs of the community that works in the oceans.