The Meteorological Buoy and Coastal Marine Automated Network for the United States (1998)

The meteorological buoy and Coastal Marine Automated Network (C-MAN) systems along U.S. coasts are designed to detect hazardous weather before it strikes the shore. Although the suite of observations from individual platforms may vary, these systems generally report information on air and water temperature, air pressure, and wind and wave conditions. Weather forecasters and researchers interested in coastal weather and ocean processes rely extensively on the data provided by the National Oceanic and Atmospheric Administration (NOAA) operated buoy/C-MAN network. Real-time observations from these stations are used by public and private weather forecasters to provide information on possible hazardous wind, sea-state, and water-level conditions to public safety officials, public and private marine interests, shipping companies, fishing and recreational interests, and the general public. These systems collect information under conditions of weather too severe for human observers, and thus provide vital information, not only for public warnings and forecasts but for research that will lead to better understanding of storm characteristics and improved forecasts.

This study responds to a request from the Administrator of NOAA to examine the meteorological buoy/C-MAN system for, primarily, its value in analyzing current weather conditions and in providing weather forecasts and warnings, and to recommend a distribution of observing platforms that would maintain essential weather forecast capabilities. Prompting this request was a shortfall in funding that places 33 of the 118 buoy/C-MAN stations in jeopardy. In further discussion with the Administrator and NOAA's chief scientist and staff, it was recognized that identification of specific platform placements would have to be done taking factors into account that were beyond the scope of this study, such as identification of populations most at risk to coastal weather-related hazards. The study nonetheless identifies such factors and defines a strategy, based on scientific principles, for ultimately determining these platform locations.

It is important to note that quantitative studies of the value of specific components of the surface (land and marine) observational network (in-

cluding the buoy/C-MAN system) do not exist. There is no rigorous study that has evaluated the impact of forecast quality for a specific surface station. Ongoing studies in conjunction with the North American Observing Strategy (NAOS) are trying to evaluate this issue quantitatively, but no definitive results have yet been established. While some experimental results do demonstrate that marine observations have a positive impact on numerical initialized analyses and forecasts, the research necessary to prove their value remains to be done. Without more extensive numerical analyses, recommendations to expand the network of observing sites are admittedly, largely judgmental, but are based on many years of forecaster experience. Therefore, the recommendations that follow are based on the value of the buoy/C-MAN system to the preparation of storm watches and warnings, the demonstrated value to public safety and recreational and commercial uses, the needs of the research community, and the importance of surface observations to calibrate (or “ground truth”) observations made remotely from space-based instruments.

The rapidly increasing U.S. coastal population is particularly vulnerable to the disruptive effects of coastal flooding, storm surges, intense extratropical storms, and tropical cyclones (TCs); therefore, it depends on accurate and timely warnings of severe weather. Coastal weather forecasters at the National Weather Service (NWS) rely extensively on the data provided by the NOAA operated buoy/C-MAN network. Researchers also depend on the buoy/C-MAN network for data that will lead to better understanding of storm characteristics and improved forecasts.

Such a core network could be based on NOAA's 1995 Marine Observation (MAROB) plan. The MAROB plan is founded on the concept that the observational data density coverage from buoy/C-MAN locations has to be increased in recognition of the growing marine (coastal and offshore) responsibilities of the modernized and restructured NWS. The MAROB plan calls for the present number of observing platforms to be increased by approximately 200 stations (above the current base-funded total of 69 C-MAN and moored buoy stations) to provide adequate support for weather forecasting operations. In essence, the study herein agrees with that assessment. However, while the MAROB plan appears reasonable, the exact

number and placement of observing platforms should be determined through more objective assessment and numerical analyses.

The fine tuning required to update the MAROB plan should consider the increased warning responsibilities of the NWS, the inextricable linkage between the operational and research communities, and the strategy outlined below. The proposed modifications to the core MAROB plan include:

• addition of moored buoys around Hawaii, the eastern Pacific, Gulf of California, Gulf of Mexico, the Atlantic coast, and the Caribbean with locations to be determined based upon operational and research requirements;
• increased use of adaptive data gathering strategies to allow deployment of additional drifting buoys in the central tropical Atlantic during the hurricane season and over the open ocean waters when the potential exists for severe extratropical cyclones (ETCs) to threaten coastal regions; and
• replacement of some C-MAN systems by moored and drifting buoys in areas where the C-MAN sites are situated near land-based coastal surface observation sites.

Implementation of this recommendation will require a long-term commitment from federal agencies to support the buoy/C-MAN network. Management and funding responsibility for the existing buoy/C-MAN network is spread across multiple federal agencies that often have different interests, funding commitments, and data requirements. Recent funding cuts that threaten the continued operation of 33 of the 118 existing buoy/C-MAN stations are an indication that the existing management approach is a barrier to the long-term stability of the system. Stability of operations requires that a single federal agency, NOAA, be given the responsibility and means to install, operate, and maintain the core, base-funded network. Firm agreements among collaborating agencies are needed, as is a continuing mechanism to oversee and review the implementation and operation of the system. A biennial report on the status of the network by a team of experts drawn from the NOAA operations community, other agency and private sector user groups, and the academic research community could serve as that continuous mechanism.

A comprehensive plan for integrating disparate observational systems that are crucial to weather forecasting and climate monitoring does not exist. If the data obtained from the core buoy/C-MAN network are to be

used most effectively in forecasting and research applications, they need to be integrated with data from land-based and remote-sensing observational platforms to create a comprehensive global data set.

Both review and study are essential if the United States is to meet its international commitments in the weather and climate arena and provide its citizens with more timely and accurate warnings of hazardous weather, particularly in the increasingly populated coastal regions. Throughout this report there are many reminders that operational responsibilities and research are inextricably linked. Although this study concentrates on the weather and climate applications of the buoy/C-MAN network, there are many other applications for ocean, ecosystem, and environmental sciences.

The decision as to where and how fast changes should be made in the existing network is difficult and beyond the scope of this study. For example, although costs were considered in order to demonstrate that the network is realistically attainable, what the U.S. government can actually afford at this time is left to the agencies responsible for deployment of the system.

However, this report does outline a strategy for assessing costs and expected benefits. The analysis will further help identify priorities for platform and instrument installation and strengthen community support for the program. Such an analysis is part of a recommended strategy for guiding decisions on buoy/C-MAN placement. The strategy should consider the following points.

• It is necessary to identify those coastal areas most prone to storms and assess the magnitude of danger from them, including assessment of where populations are most dense and where those at risk are without the means of either protecting themselves or retreating from an advancing storm.

• It is important to consider which coastal regions are most prone to locally hazardous conditions, such as fog related and coastal upwelling.
• The strategy should consider the coastal population density and the magnitude of the seasonally varying coastal storm threat in any buoy/C-MAN deployment, repair, replacement, and abandonment decisions.
• It is necessary to consider the scale of storms, so that the network is not so thin as to miss important characteristics of storm intensity and direction of movement.
• The strategy should consider that new and important ways to apply buoy and C-MAN data will continue to emerge as more people learn that they can obtain and use the data.

An overall approach for making decisions about how, where, and when to implement the recommended buoy/C-MAN system should be based on the above five criteria, as well as the two technical recommendations discussed above.

Observations in and of themselves are of limited value unless they are coupled with an operational data assimilation system and forecast model. Consideration of observation priorities also must take into account the maintenance and upgrades of the forecast and warning system that uses the observations.