Data sources and corrections

Overall, COADS Release 1a offers a substantial augmentation in weekly numbers of reports in comparison to the interim data (Fig. 1A). When the comparison is restricted to ship data, inclusion of delayed international logbook reports is shown to yield a large benefit with the passage of time (Fig. 1B). In addition, the logbook reports contain important information, such as the sea surface temperature (SST) measurement method indicator, not currently available in GTS reports. Besides the available international logbook data, records from the Russian Marine Meteorological Data Set have been included, as well as special fishing fleet data that helped fill important gaps in data coverage in the tropical Pacific.

Automated platform data have been similarly improved and expanded by including three important sets of delayed, quality-controlled data:

  • Global drifting buoy data prepared by Canada's Marine Environmental Data Service (MEDS). For 1992 it should be noted that the MEDS data set includes proprietary World Ocean Circulation Experiment (WOCE) buoys from which only the 2-degree monthly summaries are available to the general research community, not the quality controlled individual observations.

  • Hourly moored buoy and Coastal-Marine Automated Network (C-MAN) data from the NOAA National Data Buoy Center (NDBC).

  • Data from NOAA's Pacific Marine Environmental Laboratory (PMEL): (a) Tropical Ocean-Global Atmosphere (TOGA) Program TAO ATLAS moored buoys, and (b) daily averages from Equatorial Pacific Ocean Climate Studies (EPOCS) moored buoys and low-elevation island stations.

As part of Release 1a, a number of important corrections and archival improvements has been implemented in the basic GTS data used for the interim products and also in the delayed ship logbook reports. For example, data from NOAA's National Meteorological Center (NMC), which form the bulk of the basic GTS input for Release 1a, were reprocessed at the National Climatic Data Center (NCDC) to correct a number of errors in conversion from the original NMC format associated with code changes and insufficient documentation, e.g., doubled wind speeds from ships reporting meters per second during the approximate period February-June 1984. [NOTE: The doubled wind problem applies only to preliminary sets of interim products obtained before October 1987; see printed interim information.]

Similarly, U.K. logbook reports containing erroneous SST measurement method indicators were replaced from update tapes. Another example of a problem in the logbook data, extending through 1988, is a displacement of French reports by 10 degrees of longitude within 90E-90W across the dateline, due to a WMO code ambiguity. Replacement data have been received from France; however, because of questions about the exact duration of the problem, it was possible for Release 1a only to delete the logbook reports under the assumption that they would be replaced in many cases by properly located GTS data. Several comparatively minor archival problems were also left partially corrected or uncorrected in other data sources, awaiting future updates. Electronically available documentation for COADS products includes additional information about data problems and corrections.

Introduction | Data sources and corrections | Improvements in processing and products | Discussion | Future plans | Acknowledgements | References

U.S. National Oceanic and Atmospheric Administration hosts the icoads website privacy disclaimer
 Document maintained by icoads@noaa.gov
Updated: Nov 8, 2005 23:57:03 UTC
http://icoads.noaa.gov/coads1a_sources.html