Preliminary results of comparisons between Tropical Atmosphere Ocean (TAO) oceanographic refresh and Legacy sensors

As part of the transition of the Tropical Atmosphere Ocean (TAO) program, NOAA´s National Data Buoy Center (NDBC) is testing commercial off-the-shelf (COTS) components to replace obsolescent sensors. The ldquorefreshrdquo of TAO will also include changing to a transmission system that allows hourly receipt of high-resolution data, and incorporating a new payload. Six refresh buoys will be deployed within 10 kilometers of existing TAO buoys. Meteorological and ocean sensors will be compared in order to verify that the refresh system replicates the data provided by the ldquolegacyrdquo TAO system. Two refresh buoys have already been deployed along the TAO 140degW line at 9degN and 2degS. . An analysis of the first three months of oceanographic data from these two buoys is presented and discussed. The temperature sensors were compared in a laboratory setting and the results were very good. While the ocean temperatures from the refresh buoys are reported at ten minutes intervals every hour via the Iridium satellite constellation, the legacy buoys report ten minute data over Service ARGOS as the polar satellites pass the buoys. At the 2degS,140degW site, eight of the ten ocean temperature sensors reported data that is statistically equivalent to the legacy buoy temperatures. The other two refresh temperature sensors at 20 and 80 meter depths failed to report. Five of the ten ocean temperature sensors at the 9degN, 140degW site reported statistically equivalent data. Data from two of the legacy TAO sensors were failed by TAO analysts prior to deployment of the TAO program. Comparison of the other three temperature sensors yielded results that were not statistically equivalent. The region between 40 and 120 meters depth is characterized by a sharp temperature gradient. The environment may be responsible for the variability between the sensors in this region. Following recovery of the legacy and refresh buoys during fall 2008, the 10 minute data from the temperature sensor- s will be downloaded and NDBC and the NOAA´s Pacific Marine Environmental Laboratory will perform an in-depth analysis.