Comparison of the NDBC 2.1-Meter SCOOP Buoy to the Operational 3-Meter Buoy

Abstract

NOAA's National Data Buoy Center(NDBC) is undergoing a technical refresh of the coastal weather buoys around the United States. This refresh is threefold: one, a change in the computer system (payload) installed on the buoy: two, a change in the hull size of the buoy; and three, a change in the sensors installed on the buoy. Side-by-side testing is being conducted at two locations, with a third location to be evaluated during 2018. The two comparison sites are at 44014, Virginia Beach, VA in the Atlantic Ocean and at 46029, Columbia River Bar, OR in the Pacific Ocean. The third location for 2018 will be 45001, mid Lake Superior in the Great Lakes. Both 2.1-meter hulls were deployed for approximately one year. The data collection system installed on the 2.1-meter buoy is a new system called the Self Contained Ocean Observing Payload (SCOOP). This system has undergone much testing prior to being deployed in the field. The field test is the final phase of testing prior to declaring this system fully operational. The 3meter hulls have two different data collection systems. The 3meter buoy at 44014 has the Acquisition and Reporting Environmental System (ARES) payload, while the 3-meter buoy at 46029 has the Advanced Modular Payload System (AMPS) payload. The sensors being compared include meteorological sensors such as anemometers, air temperature and relative humidity sensors, and barometers. The comparison will take into account the physical differences between the 3-meter diameter hull and the 2.1-meter diameter hull as well as the changes in the sensors themselves. The anemometer data on both hulls will be adjusted to a standard height of 10 meters to account for the height difference of the sensors between the hulls. Barometer data is adjusted to sea level, again due to the difference in height. Wave measurements (height, period, and direction) will also be analyzed and compared in a separate report. High resolution 10-minute data are the basis for comparison in most cases. In some cases, hourly data are compared due to the lack of high resolution data from the 3-meter hulls. The means and standard deviations for the 3-meter and 2.1-meter wind speed and direction, air temperature, relative humidity, dew point temperature, and barometric pressure are compared. The mean and standard deviation of the difference between the sensors, the difference root mean square value, and the maximum and minimum differences are also presented. Finally, the slope and intercept values for the regression between the two sensor time series are presented. The same statistical testing is applied to the height corrected wind speeds. Preliminary results for the first six months of data indicate that the meteorological sensors from the 2.1-meter hull are within NDBC accuracy values, with the exception of relative humidity at Virginia Beach and wind direction at Columbia River Bar. These particular measurements will require the full year of data to determine their validity. Data return for all sensors is in excess of 98%. Any discrepancies discovered in the data will be noted and investigated. Information on the condition of the buoy and instruments upon recovery will be incorporated into the evaluation. Additionally, any activity noted during the daily quality control of the data will be utilized and applied, as necessary.