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ENSEMBLES (EN3): quality controlled in situ ocean temperature and salinity profiles

The EN3 data set contains global, sub-surface ocean profiles of temperature and salinity for 1950-2006 inclusive. They were quality controlled using a comprehensive set of objective checks developed at the Met Office Hadley Centre - drawing on documented procedures from other centres where appropriate. The quality control was applied consistently over the whole period, and the checked profiles were output in a uniform format (NetCDF).

Brief description of the data

The profiles were obtained primarily from the WORLD OCEAN DATABASE 2005, but this was supplemented using data from other sources: GTSPP for 1990 onwards and the USGODAE Argo Global Data Assembly Center (GDAC) for Argo data from 1999 onwards. The processing was performed for the EU supported project ENSEMBLES. Earlier quality control development and processing was performed for the EU ENACT project. A useful by-product of the system is a "model-free" monthly objective analysis, see Ingleby and Huddleston (2007, section 4.6) for details.

The processing and quality control applied is aimed primarily at data assimilation - this is particularly reflected in the data thinning used (1 hour in time, +/- 0.2 degrees latitude/longitude) and the "superobbing", to form daily averages, of some buoy data. As with any quality control system there are some errors of both types (flagging of some "good" values, omitting to flag some "bad" values) and there are some grey areas where the reported values may sample real oceanic features that are too small to be resolved by current global ocean models.

For a detailed description of the dataset and its production process, see the cited paper (in references section). We recommended you read this and the further information (below) before using the data.

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References

When using the data set in a paper, the following is the correct citation to use (pdf file):

Ingleby, B., and M. Huddleston, 2007: Quality control of ocean temperature and salinity profiles - historical and real-time data. Journal of Marine Systems, 65, 158-175 10.1016/j.jmarsys.2005.11.019

Figures

The plots to the left show data coverage for January 2005 - note that earlier years were much more data sparse - and a timseries of the numbers of reports per month. The introduction of deep-sea moored buoys (shown in green) and profiling floats (shown in purple) - mostly Argo floats - has significantly improved data coverage (rejected floats are shown in light blue). EN3 contains significantly more data of these two types than the previous version EN2. Bathythermographs are shown in red and research profiles, mainly CTDs, in blue.

Other information

Ingleby and Huddleston (2007) documents the EN2 release. The quality control for the EN3 release is largely unchanged, but the following changes were made:

updated input data sources
a revised climatology is used for initial conditions and relaxation
more effort on "reject-lists"

See EN3_changes and EN3c_changes for more details and argo_notes for issues relating specifically to Argo data.

For each year there is a tar file containing two files per month. The monthly files contain: 1) the reports for that month - in NetCDF format and 2) some statistics for that month. The NetCDF format is a slightly extended version of that used for Argo data, it contains up to 150 levels for each report (the report is thinned vertically if necessary). Duplicate reports are not included. The quality control flags should be checked before use - for more details of this and other aspects see EN3_files.

Updates: v1b excluded some poor profiling float data in the years 1994-2005. v1c corrected an error in the TEMP variable and added 2006. See EN3c_changes for details (4 May 2007).