Ocean Observing and Climate
Joint Grant Scheme VOS Metadata Project - WP1 - Metadata

Introduction

Since 1955 the World Meteorological Organization (WMO) has collected metadata for the ships taking part in the Voluntary Observing Ships (VOS) Program. This metadata has been published in WMO Publication 47 (Pub. 47), the "International List of Selected, Supplementary and Auxiliary Ships" and contains information on the observing methods and practices for each ship together with information about the ship itself. Information on the evolving content of Pub. 47 metadata can be found in:

  • Kent, E. C., S. D. Woodruff and D. I. Berry, 2007: WMO Publication No. 47 Metadata and an Assessment of Voluntary Observing Ship Observations. Journal of Atmospheric and Oceanic Technology, 24(2), 214-234, DOI: 10.1175/JTECH1949.1.

Whilst this metadata has been collected for operational purposes it is also important for climate research. For example, measurements of both the air temperature and wind speed over the ocean depend on the measurement height and to create a homogeneous time series need to be adjusted to a common reference height. If the changing platform height is not accounted for it has been shown to causes artificial trends in the data, e.g.

  • Rayner, N. A., D. E. Parker, E. B. Horton, C. K. Folland, L. V. Alexander, D. P. Rowell, E. C. Kent and A. Kaplan, 2003: Global Analyses of SST, Sea Ice and Night Marine Air Temperature Since the Late 19th Century. Journal of Geophysical Research , 108(D14), 4407, DOI: 10.1029/2002JD002670.
  • Thomas, B., E. C. Kent, V. Swail and D. I. Berry, 2007: Trends in Ship Wind Speeds Adjusted for Observation Method and Height. International Journal of Climatology, submitted, pdf icon PDF Preprint.

Availability, accessibility and reliability issues have meant that in the past the metadata have not been widely used. This work package aimed to take all the available metadata from Pub. 47 and to create a single database of metadata checked for consitency and accuracy. This would then be used, together with the metadata available in ICOADS, to summarize and characterize the observing instruments and methods used by the VOS Fleet over the past 50 years.

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