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Ensemble of subsurface databases

Ensemble of subsurface databases

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Ensemble of subsurface databases

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  1. Ensemble of subsurface databases Simon Good, presented by Nick Rayner , ERA-CLIM workshop on observation errors, Vienna, April 19-20th 2012.

  2. Construction of a subsurface dataset involves many choices • Different choices are made for each dataset (EN3/WOD/CORA etc.), so each is different to the other • How much does this uncertainty impact applications? Duplicate profile detection? Thinning/ interpolation to standard levels? Choice of data sources? Quality control procedures? How to adjust for biases? Etc…

  3. Assessing the impact of dataset construction uncertainty • To understand the impact, we can apply each dataset to an application • The range of outcomes indicates the uncertainty • This is the ‘ensemble of opportunity’ approach • This is currently not straightforward to do since: • Different datasets use different file formats • In the case of bias adjustments for XBT and MBT data, it is often necessary to apply methods described in papers to the datasets • It is inefficient for each user to do this individually • The aim of deliverable 4.7 is to overcome these issues by compiling the ensemble of opportunity and providing it to users

  4. Current status • XBT and MBT bias adjustments have been applied to the EN3/EN4 dataset resulting in multiple versions of the data, each in the same file format • Plot shows the result of applying the ensemble to calculate global upper ocean temperature anomaly • Other datasets e.g. WOD are being converted to the EN3/EN4 file format

  5. What is the best way to provide the ensemble to users? • Simplest option is to provide each dataset separately in the same format (e.g. the EN3/EN4 file format) • Inefficient as there is much repeated information in each realisation of the data • It is not easy to compare the realisations • Would another option be more useful? • E.g. holding all the datasets in a single database • How do users wish to obtain the data? • E.g. download all the data at once, separate set of files for each dataset?