Overview of the UOT DAC System

The data flow within the UOT DAC system is sufficiently complicated and woven into operations of the GTSPP (Global Temperature Salinity Profile Project) that it is useful to draw a diagram that illustrates it. The convention used here is to refer to low and high resolution data. Low resolution data normally are those which are in sent in real-time (J-COMM, Joint Technical Commission on Oceanography and Marine Meteorology, defines real-time to be any data exchanged within 30 days of collection) formats of BATHY or TESAC. Typically these report observations at inflection points in a profile. BATHY permits reporting temperatures to 0.1 degrees C and is most often used for XBT data, TESACs permit reporting both temperature and salinity profiles, both to two decimal places. High resolution data are those that reflect the sampling capabilities of instrumentation. For example, CTD data typically are handled at 1 m resolution and are considered to be high resolution data.

The diagram below makes no distinction between data of primary interest to GTSPP and those of interest to WOCE. Generally, the low resolution data are of less interest to the UOT. However, there is always a considerable delay in some high resolution data reaching the archives, and it is considered advantageous to have at least the low resolution data if the high resolution data have not yet arrived. Also, by monitoring the data received in real-time, it is possible to know where platforms are operating and collecting the high resolution data. One can look at the sampling along WOCE lines, and the distribution over the world's oceans and so influence the sampling strategy. For these reasons, the UOT DAC system is an assembly of partners each undertaking specific aspects of the work.

The top part of the diagram deals largely with low resolution data flow. The bottom shows the data flows into and out of the Continuously Managed Database, CMD, established at the U.S. NODC. Arrows indicate the direction of data flow.

The Atlantic Oceanographic and Meteorological Laboratory offices in Washington (here designated OAR) act as the conduit through the Internet for low resolution data from the National Meteorological offices each day. The Marine Environmental Data Service, MEDS, receives data from its own link to the GTS (Global Telecommunications System). Also on a daily basis, the Japan Meteorological Agency sends BATHY and TESAC data that they have extracted from the GTS.

MEDS processes BATHY and TESAC data taken from the GTS by the Bundesamt für Seeschiffahrt und Hydrographie, BSH, and forwarded after the end of each month by Internet ftp. These data and the daily files are used in the production of the GTSPP monthly reports to the SOOP (Ship of Opportunity Programme) Co-ordinator. Data in these files, which are missing from the daily files are added to the GTSPP data flow.

Data exchange is shown from the Japanese Oceanographic Data Center, JODC. These data are transferred electronically to MEDS at the end of each month. These are data collected from Japanese fisheries and defense ships. Temperatures are sampled at 0, 100, 200 and 400 m only and time of day is not available for the stations.

The box labeled NAVOCEANO represents the US Navy oceanographic centre in Bay St. Louis. Data files are transferred to them on the same schedule as to NODC.

There is a box labeled Users. Data are forwarded each month to oceanographic institutes on each coast of Canada. As well, MEDS sends files three times a week to international users including agencies in the U.S., in French Polynesia and the NEAR-GOOS programme operating in Japan.

On the left-hand side of the figure is represented the three centres, Miami, Scripps and CSIRO that carry out scientific quality control of data. (Note that CSIRO and the Australian BMRC cooperate to run the Joint Australian Facility for Ocean Observing Systems, JAFOOS, under whose responsibiity this work falls).The data are relayed electronically from NODC each year. Each centre has the responsibility to return the data with the updated quality control indicators to the NODC. Additionally, AOML gets the real-time Atlantic Ocean data from MEDS and QC's them on a bimonthly basis.

The low resolution data are forwarded to the Australian SOC (a J-COMM Specialized Oceanographic Centre) and contribute to the holdings of this agency. In a letter to the IOC, the Australians stated that the volume and quality of the GTSPP data exceeded what they were able to acquire through their own resources and hence they would use GTSPP data as the basis of their data holdings. Work also is underway to provide data and information to the SOC for the Southern Ocean in Argentina.

The low resolution data relayed to NODC are passed along to researchers in the U.S. running global atmospheric models for use in a coupled ocean-atmosphere model. They receive the files three times each week and the data are included in weekly model runs. Likewise, the Bureau of Meteorology Research Centre, BMRC, in Melbourne, Australia, copies the files for use in their modeling. The European Centre for Mid-Range Weather Forecasting, ECMWF, also acquires files from NODC.

NODC relays temperature profile data to the World Ocean Circulation Experiment Subsurface Data Center for the Upper Ocean Thermal programme situated in Brest, France. The data are sent each month via Internet.

On the right of the NODC box is the Global Ocean Data Archaeology project, GODAR. This has been lead by the World Data Centre A, WDCA.

Another box represents the other World Data Centres. As data reach the NODC, they become available to other data centres around the world.

There are at least two routine users of the low resolution data forwarded by NODC. One is a researcher at the University of Delaware, and a second is at the Jet Propulsion Laboratory.

If you have data that you would like to contribute either in real-time or delayed mode please talk to Bob Keeley (keeley@meds-sdmm.dfo-mpo.gc.ca) or Charles Sun (csun@nodc.noaa.gov).