GTS Data Distribution
Mooring data from TAO, TRITON, PIRATA and RAMA arrays are distributed on the Global Telecommunications System (GTS). Observations include winds, air temperature, relative humidity, sea surface temperature, sea surface salinity, barometric pressure, ocean temperature, salinity and current velocity. Data submission pathways and frequency of reporting are dependent on the type of mooring system deployed.
Historically, most data were produced by ATLAS systems, the data from which were distributed on the GTS by CLS America (nee Service Argos). As part of our data quality monitoring, PMEL identifies and informs CLS America of data that should not be submitted to the GTS. In turn, Service Argos makes available to PMEL data submitted to the GTS, which PMEL compares with locally processed data for consistency. Hourly surface messages are available in World Meteorological Organization (WMO) code form FM 18-X BUOY with bulletin header SSVX08 KARS. In February 2007 NDBC assumed responsibility for quality control of TAO ATLAS data on the GTS. PMEL continues to quality control PIRATA and RAMA ATLAS data.
Prior to February 2005, ATLAS moorings transmitted data 8 hours per day (0600-1000 and 1200-1600 local times). Moorings deployed since the beginning of 2005 transmit 16 hours per day from 0000-0400, 0600-1000, 1200-1600, and 1800-2200 local times. (Click here for equivalent GMT transmit windows). Hourly surface messages are generated whenever Argos receives a satellite pass, typically 8-14 times per day for ATLAS moorings. The shift from 8 hour to 16 hour per day transmissions, combined with the use of all available NOAA satellites for data transmission, has resulted in a quadrupling of real-time surface TAO data reaching operational centers since 2005. ATLAS subsurface temperature and salinity data are available in real time only as daily averages with a time stamp of 1200z at the end of the average period. Only one subsurface message per day per buoy is available.
Typically, about 80% to 90% of ATLAS data received at PMEL are available on the GTS. A time lag between observation and availability on the GTS is due to a combination of the ATLAS sampling and transmission schedule, telemetry paths of the NOAA satellite system, and CLS America processing time. Over half of the TAO data placed on the GTS are available within 3 hours or less and over 90% are available within 7 hours.
TAO Refresh systems, NDBC’s replacement for ATLAS systems deployed in TAO, telemeter data via Iridium. Quality controlled TAO Refresh data are distributed on the GTS by NDBC (data details). WMO numbers for the TAO Refresh buoys are those used for the previous ATLAS moorings at the same sites.
T-Flex systems, PMEL’s replacement for ATLAS systems deployed in PIRATA and RAMA, telemeter data via Iridium, with calls made at 6-hour intervals. Quality controlled T-Flex data bulletins originating at PMEL have Bulletin Header IOBX08 KPML and are encoded in FM 94 BUFR format according to WMO code template 3 15 008: ‘Sequence for the representation of data from moored buoys’. WMO ID numbers for T-Flex moorings take the 7-digit analog of the 5-digit code for the previous ATLAS system at the same site. For example, WMO number 23010 for an ATLAS system is 2300010 for a T-Flex system deployed at the same location. For fully-instrumented T-Flex moorings, bulletins can include:
- Atmospheric Pressure
- Air Temperature
- Relative Humidity
- Wind Direction
- Wind Speed
- Wind Gust Speed
- Sea Surface Temperature
- Long Wave Radiation
- Short Wave Radiation
- Sea Water Temperature
- Current Direction
- Current Speed
Each submission to the GTS is comprised of hourly bulletins, containing all hourly observations communicated in the latest Iridium call, with a maximum of 6 bulletins. Thus, observations are available on the GTS with a typical time lag of 0.5-7 hours.