The World Ocean Circulation Experiment

The oceans are a key element in the climate system because they transport heat and fresh water and exchange these with the atmosphere. The World Ocean Circulation Experiment (WOCE) was a part of the World Climate Research Programme (WCRP) which used resources from nearly 30 countries to make unprecedented in-situ and satellite observations of the global ocean between 1990 and 1998 and to observe poorly-understood but important physical processes. The Scientific Steering Group (SSG) of WOCE oversaw the scientific development and the International Project Office (IPO) the implementation of the Experiment. See the Design and Implementation of WOCE and the WOCE Data System for further details.

The resulting diverse WOCE data sets contained on these disks will serve as a unique resource for climate researchers and marine scientists for decades to come.

Standardization of file format and structure using netCDF and a COARDS/WOCE convention for the variables is a significant step in the integration of the WOCE dataset as is the availability of an inventory and a search tool which can locate files according to chosen parameter ranges.

The table summarises the data content of the DVDs.

Following the production of the DVDs, Updates and Amendments  to the contents will be posted on-line. You may order copies of the DVD WOCE Global Dataset Version 3.0 from the US National Oceanographic Data Center (NODC). The content of the DVDs will also be available on-line at http://www.nodc.noaa.gov/woce_v3/ .

The present widely varying granularity (resolution) of the inventories of each DAC reflects the traditional methods of presentation of each data set. An optimum inventory for space, time, parameter searches across the whole WOCE resource will possibly look rather different.

Each WOCE Data Assemby Centre (DAC) adopted and has fully described the quality control procedures appropriate to their specific observations.The satellite datasets were assembled by JPL/USA and CNES/France. A brief summary of the quality control procedures at the DACs follows:

Hydrography
The one time surveys were examined intensively by PIs , DACs and by Data Quality Evaluators (DQEs) cross-comparing to other WOCE and historical data. The repeat surveys were largely checked by the WOCE Hydrographic Programme Office against historical data and for internal consistency.

Current Meters
Current meter data was examined by the DAC for spikiness and instrument performance. If necessary interpolated and replacement data are suggested over small segments.

XBTs (Upper Ocean Thermal Data)
XBT data was examined firstly for position consistency and quality of record and then by science groups for climatological consistency. Note: XBT high density lines were treated essentially as repeat hydrography lines without the salinity.

Sea level
The in-situ tide gauge data (part of the Global Sea Level Observing System (GLOSS) network with an emphasis towards island stations) were originally processed through two separate streams which have generally converged towards similar results.

The fast stream, intended for rapid use in conjunction with altimetry, generated data sets with typically a month's delay, but initially without all the ground controls for a long term set, though these were incorporated later.

The delayed mode set retained the original raw data and assembled the reference information necessary to bring the data to a common stable baseline at a later date.

Floats
The relatively small community of ‘floaters’ largely quality controlled their own data and generated datasets which were assembled into common format by the DAC.

Drifters
Surface drifters, the majority drogued at 10m, made use of the operational ARGOS satellite system for initial data collection, but thereafter were put through quality control and interpolation to standard intervals as well as cross checking against other nearby drifters.

Shipboard ADCP
This technique came of age during WOCE and quality control procedures developed in association with the DAC were adopted and adapted widely. The DAC scrutinises the datasets carefully but does not amend or flag the datasets, relying on the submitting PIs to subscribe to guidelines issued by the DAC.

Surface Meteorology
The majority of WOCE ships submitted surface observations. These were carefully quality controlled and range in type from high resolution automatic systems (~1minute) to standard bridge observations (once a watch).

Profiling Floats
These data, from profiling ALACE floats have been quality controlled only by the PIs. They yield vertical TS profiles, at typically 10m resolution, over periods of years at intervals of ~10 days. The floats were just coming into wide use at the end of WOCE.

Sea Surface Salinity
These data, which included both underway temperature and salinity observations from thermosalinographs on ~120 cruises were only checked by the originators. The data centre checked positional and time consistency.

The data of most WOCE data streams have been compiled in integrated, global or basin-wide datasets for easy access and analysis with the Ocean Data View (ODV) visualization software. This "Electronic Atlas of WOCE Data" (eWOCE) can be found on DVD 2.