1. QA/QC Methods for 13 MHz Brant Beach (BRNT) Test Case
Colin Evans, Ethan Handel, Hugh Roarty, Scott Glenn
Introduction
A test case was conducted for a Rutgers 13 MHz system located in Brant Beach, NJ (BRNT). Unusual large variations in the radial magnitudes during the first week of May, 2012 indicated a potential problem with the antenna and/or an issue in the First Order processing. Reprocessing with a higher noise factor of 6.3 (8dB) and a maximum radial velocity of 60 cm/s instead of 180 cm/s was conducted and compared to the real time radials from the neighboring 13 MHz sites in Seaside Park, NJ (SPRK) and Brigantine, NJ (BRMR).
Anomalies in the Radial Field
FIGURE 3. Standard deviation plots for SPRK, BRNT, and BRMR. The averaging method included a minimum requirement of 12 vectors for each range and bearing. The color indicates the current direction relative to the radar location and the size of the dot represents the magnitude of the standard deviation. a) b)
FIGURE 2. BRNT radial field during test case study for (a) ideals and (b) measured.
In order to retain a better understanding of what the radial field was showing overtime, the standard deviation for each range and bearing was applied to a 24-hour radial velocity average.
After examining the quality of the data at the radial level, the next logical step is to analyze the spectra and First Order Line settings.
First Order Line Settings
During real time processing, a portion of the Second Order Bragg was being processed as First Order. After reprocessing with the FOL changes, the Bragg peaks were more defined.
FOL Setting
Real Time
Reprocessed
Factor down peak nulls
501.19
10.00
Noise Factor
4 (~6dB)
6.3 (~8dB)
Maximum Radial Velocity
180 cm-s
60 cm-s a) b)
FIGURE 4. First Order Bragg Processing with real time FOL settings (a) compared to reprocessed settings (b). The table to the right displays the different settings.
FIGURE 1. (a) Location of the Rutgers 13 MHz CODAR sites. Blue represents Seaside Park, NJ (SPRK), red represents Brant Beach, NJ (BRNT), and green represents Brigantine, NJ (BRMR). (b) SPRK site location. (c) BRNT site location. (d) BRMR site location. b) a)
A significant change in the radial field was the result of the new FOL settings. The radial velocities were compared to NOAA tide station water levels and neighboring 13 MHz radars. a) b) c) c) d) d)
FIGURE 5. Subplots comparing the BRNT hourly averaged real time and reprocessed radials to the NOAA Atlantic City tide gauge water level measurements (a) and to the real time hourly average radial velocities from the neighboring 13 MHz sites. The reprocessed standard deviation plots are shown to the right for the ideal (c) and measured radials (d).
The data used from each 13 MHz site was collected from a combined transmit/receive dome-style antenna.
ACKNOWLEDGEMENTS: This work was funded by NOAA Award Number NA11NOS “Towards a Comprehensive Mid-Atlantic Regional Association Coastal Ocean Observing System (MARACOOS)”. Sponsor: National Ocean Service (NOS), National Oceanic and Atmospheric Administration (NOAA) NOAA-NOS-IOOS / CFDA: , Integrated Ocean Observing System Topic Area 1: Continued Development of Regional Coastal Ocean Observing Systems.
The radars were purchased under a grant from the New Jersey Board of Public Utilities entitled “An Advanced Atmospheric/Ocean Assessment Program Designed to Reduce the Risks Associated with Offshore Wind Energy
Development Defined by the NJ Energy Master Plan and the NJ Offshore Wind Energy Economic Development Act”