Status of the Tropical Atmosphere Ocean (TAO) Array Refresh Effort

The Tropical Atmosphere Ocean (TAO) array in the equatorial Pacific Ocean has provided high quality data in support of El Nino prediction and climate research since the mid-1980's. The National Data Buoy Center (NDBC) and the Pacific Marine Environmental Laboratory (PMEL) are currently transitioning the last part of the TAO array from research to operations. The software that supports the database, webpage and real-time processing has been transitioned, as well as the maintenance of the array at-sea. The Pacific Marine Environmental Laboratory (PMEL) continues to provide the instrumentation for TAO. That instrumentation is obsolescent and NDBC is implementing a plan to replace that instrumentation.

Some of the original TAO sensors were commercial sensors and others were fabricated by PMEL. NDBC plans to replace all “Legacy” TAO sensors with commercial “Refresh” sensors to extend the lifetime of the array. The wind, temperature, and relative humidity sensors are similar, although there are some differences in their enclosures. The surface salinity and temperature sensor and the subsurface inductive modem temperature sensors were PMEL designs. Commercial SeaBird sensors are being tested to determine their applicability as replacements.

Laboratory tests show the sensors agree very well. In-situ testing is now occurring and should be completed in 2011. Recently, to begin comparisons between the “Legacy” and “Refresh” buoys, NDBC deployed the new sensor suite with new payload and communications equipment on a number of TAO Refresh buoys. Two Refresh buoys were deployed within 5 to 7 kilometers of two “Legacy” buoys in September 2007 and have been recovered for evaluation. There are currently eleven additional buoys with the refresh sensors deployed.

The ten climate principles govern this transition. Network change is being managed, the software and sensors have been or are being parallel tested, and metadata are being provided. Data quality and continuity of data are being emphasized. The historical significance and continuity of purpose of the TAO array are certainly important components of the transition and access to all of the data is guaranteed.

Comparison of real-time daily averaged data indicates that the entire “Refresh” TAO system is operating at the same level as the “Legacy” TAO system. These data support the El Nino/La Nina prediction system within NOAA. Comparison of the delayed mode data is important because these data are used to determine heat content, which is one of the basic tenets of monitoring climate. If the new sensors do not report the exact same temperatures, a transform function will be developed to maintain the integrity of the climate data record.