Temperature Measurements from Surface Drifters

G. Reverdin L’OCEAN/IPSL, CNRS/UPMC, Paris, France

Search for other papers by G. Reverdin in
Current site
Google Scholar
PubMed
Close
,
J. Boutin L’OCEAN/IPSL, CNRS/UPMC, Paris, France

Search for other papers by J. Boutin in
Current site
Google Scholar
PubMed
Close
,
N. Martin L’OCEAN/IPSL, CNRS/UPMC, Paris, France

Search for other papers by N. Martin in
Current site
Google Scholar
PubMed
Close
,
A. Lourenco L’OCEAN/IPSL, CNRS/UPMC, Paris, France

Search for other papers by A. Lourenco in
Current site
Google Scholar
PubMed
Close
,
P. Bouruet-Aubertot L’OCEAN/IPSL, CNRS/UPMC, Paris, France

Search for other papers by P. Bouruet-Aubertot in
Current site
Google Scholar
PubMed
Close
,
A. Lavin IEO, Santander, Spain

Search for other papers by A. Lavin in
Current site
Google Scholar
PubMed
Close
,
J. Mader AZTI, Brest, France

Search for other papers by J. Mader in
Current site
Google Scholar
PubMed
Close
,
P. Blouch CMM, CNRM, Brest, France

Search for other papers by P. Blouch in
Current site
Google Scholar
PubMed
Close
,
J. Rolland CMM, CNRM, Brest, France

Search for other papers by J. Rolland in
Current site
Google Scholar
PubMed
Close
,
F. Gaillard LPO/IFREMER, Brest, France

Search for other papers by F. Gaillard in
Current site
Google Scholar
PubMed
Close
, and
P. Lazure * DYNECO/IFREMER, Brest, France

Search for other papers by P. Lazure in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The accuracy of temperature measurements from drifters is first examined for 16 drifters (manufactured either by Metocean Data Systems or by Pacific Gyre) deployed with two temperature sensors in the tropical or North Atlantic Ocean. One of these sensors is the SST thermistor commonly used on Surface Velocity Program (SVP) drifters since the late 1980s; whereas the other sensor is a platinum temperature probe associated with a Seabird conductivity cell. The authors find (for 19 separate deployments) an average positive offset of the SST thermistor measurements in 17 out of 19 cases, exceeding 0.1°C in five instances. Among the five drifters that were at sea for a year or more, two present a large trend in this offset (0.10° and −0.10°C yr−1); and in two other cases, there is a clear annual cycle of the offset, suggesting a dependency on temperature. Offsets in 9 out of 12 drifters with sea time longer than 4 months present a negative trend, but the average trend is not significantly different from zero. The study also examined 29 drifters from four manufacturers equipped only with the usual SST thermistor, but for which either a precise initial temperature measurement was available or a float was attached to provide accurate temperature measurements (for a duration on the order of a month). These comparisons often identify SST biases at or soon after deployment. This initial bias is null (or slightly negative) for the set of Clearwater Instrumentation’s drifters, it is very small for two out of three sets of Technocean drifters, and positive for the third one, as well as for the set of Pacific Gyre drifters (on the order of 0.05°C).

Corresponding author address: G. Reverdin, L’OCEAN/IPSL, CNRS/UPMC, Case 100, 4 Pl. Jussieu, 75252 Paris CEDEX 05, France. Email: gilles.reverdin@locean-ipsl.upmc.fr

Abstract

The accuracy of temperature measurements from drifters is first examined for 16 drifters (manufactured either by Metocean Data Systems or by Pacific Gyre) deployed with two temperature sensors in the tropical or North Atlantic Ocean. One of these sensors is the SST thermistor commonly used on Surface Velocity Program (SVP) drifters since the late 1980s; whereas the other sensor is a platinum temperature probe associated with a Seabird conductivity cell. The authors find (for 19 separate deployments) an average positive offset of the SST thermistor measurements in 17 out of 19 cases, exceeding 0.1°C in five instances. Among the five drifters that were at sea for a year or more, two present a large trend in this offset (0.10° and −0.10°C yr−1); and in two other cases, there is a clear annual cycle of the offset, suggesting a dependency on temperature. Offsets in 9 out of 12 drifters with sea time longer than 4 months present a negative trend, but the average trend is not significantly different from zero. The study also examined 29 drifters from four manufacturers equipped only with the usual SST thermistor, but for which either a precise initial temperature measurement was available or a float was attached to provide accurate temperature measurements (for a duration on the order of a month). These comparisons often identify SST biases at or soon after deployment. This initial bias is null (or slightly negative) for the set of Clearwater Instrumentation’s drifters, it is very small for two out of three sets of Technocean drifters, and positive for the third one, as well as for the set of Pacific Gyre drifters (on the order of 0.05°C).

Corresponding author address: G. Reverdin, L’OCEAN/IPSL, CNRS/UPMC, Case 100, 4 Pl. Jussieu, 75252 Paris CEDEX 05, France. Email: gilles.reverdin@locean-ipsl.upmc.fr

Save
  • Kent, E. C., and Taylor P. K. , 2006: Toward estimating climatic trends in SST. Part I: Methods of measurement. J. Atmos. Oceanic Technol., 23 , 464475.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • O’Carroll, A., Eyre J. R. , and Saunders R. W. , 2008: Three-way error analysis between AATSR, AMSR-E, and in situ sea surface temperature observations. J. Atmos. Oceanic Technol., 25 , 11971207.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rayner, N. A., Parker D. E. , Horton E. B. , Folland C. K. , Alexander L. V. , Rowell D. P. , and Kaplan A. , 2003: Globally complete analyses of SST, sea ice, and night marine air temperature, 1871–2000. J. Geophys. Res., 108 , 4407. doi:10.1029/2002JD002670.

    • Search Google Scholar
    • Export Citation
  • Rayner, N. A., Brohan P. , Parker D. E. , Folland C. K. , Kennedy J. J. , Vanicek M. , Ansell T. J. , and Tett S. F. B. , 2006: Improved analyses of changes and uncertainties in sea surface temperature measured in situ since the mid-nineteenth century: The HadSST2 dataset. J. Climate, 19 , 446469.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Rayner, N. A., and Coauthors, 2009: Community white paper: Evaluating climate variability and change from modern and historical SST observations. Proc. OceanObs’09: Sustained Ocean Observations and Information for Society, ESA Publ. WPP-306, Venice, Italy, ESA.

    • Search Google Scholar
    • Export Citation
  • Reverdin, G., Blouch P. , Boutin J. , Niiler P. , Rolland J. , Scuba W. , Lourenco A. , and Rios A. , 2007: Surface salinity measurements - COSMOS 2005 experiment in the Bay of Biscay. J. Atmos. Oceanic Technol., 24 , 16431654.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Reynolds, R. W., Smith T. M. , Liu C. , Chelton D. B. , Casey K. C. , and Schlax M. G. , 2007: Daily high-resolution-blended analyses for sea surface temperature. J. Climate, 20 , 54735496.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • Sybrandy, A. L., and Niiler P. P. , 1991: The WOCE/TOGA Lagrangian drifter construction manual. Scripps Institution of Oceanography, SIO Ref. 91/6, WOCE Rep. 63, 58 pp.

    • Search Google Scholar
    • Export Citation
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 505 188 3
PDF Downloads 109 37 5