Quality Control of Sea Level Data

From Ocean Teacher Library

Background

In January, 2008, the IOC and JCOMM convened a workshop entitled the IODE/JCOMM Forum on Oceanographic Data Management and Exchange Standards (IOC Workshop Rept. 206), to consider selected principal issues on establishing marine data standards, with the goal of furthering marine data interoperability. In particular the aim of the workshop was to get broad agreement and commitment to adopt a number of standards related to ocean data management and exchange, thereby assembling not only the agreed conditions by which we operate, but in fact enact these agreements in the participants' respective organizations.

Standards Recommendation

Dr. Lesley Rickards (UK BODC and Permanent Service for Mean Sea Level [PSMSL]) introduced this item and moderated discussions. She reviewed the various quality control procedures that exist for verifying sea level observations. She identified the following data values of sea level would be considered:

Digitised from paper chart records or obtained electronically at higher frequencies
From bottom pressure recorder data and water level recorders

Quality Control requirements may be different depending on sampling interval, latency and use to which data are put. The scope of quality control includes: (i) information (metadata) to accompany the data; (ii) automatic checks (iii) “scientific” quality control; and (iv) quality flags.

She noted that the following resources are available:

Decisions

The meeting did not identify a recommended standard;
It was agreed that Dr L. Rickards will lead the revision of the ESEAS QC document in close collaboration with the GE-GLOSS
It was agreed that Dr L. Rickards will prepare the submission document
It was agreed that Mr. R. Keeley (Canada MEDS) will write QC manual guidance material (i.e. evaluation material for standards review)

Additional Resources

PSMSL Training Information, Reports, Manuals etc.
POL/PSMSL Tidal Analysis Software Kit (TASK)
University of Hawaii Sea Level Processing Software
FFTWaveForm - The FFT program available here provides a useful teaching aid to understand the Fourier Transform of time series data a fundamental task in science and engineering.
BODC's EDSERPLO - EDSERPLO is basically a data visualisation system (i.e. for all time series and profiles, including ADCP and wave spectra), but it does not have automatic QC tests built in, as these will either already have been carried out as BODC transfers data into its internal format or they are planned but not yet implemented. EDSERPLO does perform tidal analyses, predict tides, and calculate residuals, filter to hourly values, and perform some gap filling (but only for a couple points, as opposed to more aggressive filling in other systems), and flag data values. All of these operations are supported by appropriate plotting. It also generates statistics (monthly mean sea level, extremes, surges). EDSERPLO forms part of the BODC QC process, but is not a standard in itself.

Subsections of this Article

No subsections available

Information about this article

Short title: Sea Level

Description: none

Expertise level: beginner

Author: Murray.Brown

Approval status: approved

Approved by: Murray.Brown

Last change: 2008-9-9

Subsection of: Marine Data Quality Control

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