Met Office Hadley Centre observations datasets

ENSEMBLES (EN3) quality controlled ocean data - version 1d with Wijffels et al. (2008) XBT depth corrections: Download

Dataset changes

The data on this page have a number of differences to version 1c of the dataset. These are:

Corrections to the SCIENTIFIC_CALIB_COEFFICENT and INST_REFERENCE metadata identified as being incorrect in version 1c;
Tapering of XBT corrections in colder water has been removed;
The XBT depth corrections given in Table 1 of Wijffels et al. (2008) have been applied.

XBT depth corrections

The time varying XBT depth corrections developed by Wijffels et al. (2008) and defined in Table 1 of that paper have been applied to the data. The corrections were interpolated to the date of each XBT profile, corrected depths were calculated and the depths in the EN3 files were overwritten with the new values. A new variable, WIJFFELS_DEPTH_CORRECTION, has been added to the EN3 files. This records the correction that was applied to each profile.

Exceptions to this method were:

Where the date is in error for a profile (see data section below) the correction for the centre of the month in which the profile was recorded was applied;
For profiles recorded before 1968 (i.e. before the first date for which corrections are defined), the correction calculated for 1968 was applied. Similarly the correction for 2005 was applied to all data for 2005 onwards. These XBT profiles should only be used with caution.

Particular attention should be given to the second point above. The XBT data outside the time range of the corrections may not be suitable for some applications.

It should be noted that the corrections implemented in the data accessible from this page do not match exactly those calculated by Wijffels et al. (2008). This is because the details of the implementation, e.g. the removal of the cold water tapering, are slightly different and were hampered previously by the incorrect metadata in the EN3 files. Effort has been made to confirm that the Wijffels et al. (2008) data and these data do not differ significantly. A comparison was made by Catia Domingues (CSIRO), who found that the differences were small and within error bars.

References

Wijffels, S., J. Willis, C. M. Domingues, P. Barker, N. J. White, A. Gronell, K. Ridgway and J. A. Church, 2008, Changing expendable bathythermograph fall rates and their impact on estimates of thermosteric sea level rise, Journal of Climate, 21, 21, 5657-5672, DOI:10.1175/2008JCLI2290.1

Data

Each tar file contains all the gzipped monthly NetCDF data for one year.

Please Note: A number of profiles have an incorrect value for the Julian Day (JULD), which are easily indentified as a large negative number. It is advised that these profiles be removed from any analysis using EN3 data. This problem only affects the profiles taken prior to 1970.

Downloading using wget

To download the data using wget, first use the link below to save the file 'Wijffels_XBT_corrections_download_list.txt' to your local computer.

Wijffels_XBT_corrections_download_list.txt

Assuming that you are in the directory into which the data are to be copied and that the Wijffels_XBT_corrections_download_list.txt file is also in that directory, the download can then be initiated by typing:

wget -i Wijffels_XBT_corrections_download_list.txt

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