Overview

In brief, much of the data handled by the GTSPP/UOT programme come from XBTs dropped from ships.  Some low vertical resolution data are received in real-time (less than 30 days) by ISDM each day.  After quality control and duplicates checking, the data are uploaded to the U.S. NODC three times a week.  The NODC manages the high resolution data received in delayed mode as well, passing these data through quality control and duplicates resolution processing and, replacing the low resolution records with the high resolution ones as they arrive.  Once a year, the data are forwarded to science centres (AOML, CSIRO and Scripps) for quality control and then returned to NODC for archival.  As well, NODC cooperates with the WOCE Subsurface Data Centre in Brest to ensure completeness of their holdings.

The data in the Continuously Managed Database (CMD) are the highest resolution, highest quality available at the time of production.  Because of delays in receiving and processing high resolution data, there is a mixture of low resolution and high resolution data present.  As well, some data will have undergone quality control at data centres only, while others will have passed through scientific quality assessment at science centres.  As a general rule, the low resolution (real-time) data pass through QC at data centres only, not the science centers.  Also, generally, all of the high resolution data from the 1990-1995 have passed through scientific quality control.  However, as data appear in the CMD sometimes years after they were collected, the only way to be certain that you are dealing with data that have passed scientific QC is to examine each profile.

As data pass through scientific QC at the science centres, the profiles receive data quality flags.  In addition, information is placed in the file that describes the reason why the quality of certain data are considered to be less than good.  This information is stored in the HISTORY section of the data format.

To assist a reader in getting a feel for the volume and distribution of data available, a number of summaries have been compiled.  These are meant to illustrate characteristics of the data rather than as exhaustive use of the data

In the last few years, new fall rate equations for XBTs have been brought to light (see for example, Ruel, et. al. in WOCE Newsletter, October, 1996).  In both low resolution (real-time) and high resolution data, information about the probe type, recorder and fall rate equations used accompany the data.  If this information is absent, you should assume the older fall rate equations were used.

Please note that the data in the CMD have been reviewed using techniques and standards consistent with good scientific and data management practices.  It is, however, not possible to guarantee that all errors have been detected and either corrected or flagged.  It is the responsibility of the user to review the data and information to determine the acceptability for their application.