___Argo Mixed Layers
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Introduction:

We have compiled a mixed layer depth (MLD) climatology using Argo profiles and a hybrid method (Holte and Talley 2009) for finding the MLD. The climatology incorporates over 1,250,000 Argo profiles (through May 2016). The new hybrid algorithm models the general shape of each profile, searches for physical features in the profile, and calculates threshold and gradient MLDs to assemble a suite of possible MLD values. It then analyzes the patterns in the suite to select a final MLD estimate. Results are also presented for MLDs calculated using de Boyer Montégut et al.'s (2004) threshold values.

Two forms of Argo MLDs are provided:
  • Mixed layer depths and properties (density, temperature, and salinity) for every profile in the Argo data set.

  • Climatology of monthly mixed layer depths (mean, median, maximum, and standard deviation) and properties (density, temperature, and salinity) averaged into 1 degree bins.
These files contain the mixed layer depths and properties as calculated by the density algorithm and the density threshold. Each also includes the mixed layer depths calculated by the temperature algorithm and the temperature threshold. A MATLAB version of the algorithm is also available here.
Data:
The output includes more than 1,250,000 delayed-mode and real-time Argo profiles, collected between January 2000 and May 2016. The profiles were screened with some simple quality controls.
Mixed layer depths and properties for all Argo profiles:

Both versions contain the following fields calculated for each individual Argo profile:

  • profile date
  • profile latitude
  • profile longitude
  • float number (WMO number)
  • profile number
  • status (delayed mode corresponds to 1)

  • mixed layer depth from density algorithm
  • mixed layer average temperature using density algorithm MLD
  • mixed layer average salinity using density algorithm MLD
  • mixed layer average potential density using density algorithm MLD

  • mixed layer depth from density threshold method
  • mixed layer average temperature using density threshold MLD
  • mixed layer average salinity using density threshold MLD
  • mixed layer average potential density using density threshold MLD

  • mixed layer depth from temperature algorithm
  • mixed layer depth from temperature threshold method
Monthly mixed layer climatology:

The climatology is determined by grouping the profiles into 1 degree bins and then calculating the mean, median, maximum, and standard deviation of the MLDs for each month, as well as the monthly mean mixed layer temperatures, salinities, and potential densities. These variables are calculated separately using the density algorithm and the density threshold. The maximum MLD is calculated as the mean of the three deepest MLDs. The monthly mean MLDs calculated by the temperature algorithm and the temperature threshold are also included. The climatology contains the following monthly fields averaged into 1 degree bins:

  • density algorithm mean MLD
  • density algorithm median MLD
  • density algorithm maximum MLD
  • density algorithm MLD standard deviation

  • density threshold mean MLD
  • density threshold median MLD
  • density threshold maximum MLD
  • density threshold MLD standard deviation

  • mean mixed layer temperature, salinity, and potential density calculated with the density algorithm mean MLD
  • mean mixed layer temperature, salinity, and potential density calculated with the density threhsold mean MLD

  • temperature algorithm mean MLD
  • temperature threshold mean MLD
If you use this data, please cite it as:
Holte, J., J. Gilson, L. Talley and D. Roemmich, 2016: Argo Mixed Layers, Scripps Institution of Oceanography/UCSD http://mixedlayer.ucsd.edu, (accessed [date]).
Links:
  • Argo data browser
  • Ocean Sciences presentation on the Argo MLD climatology
  • Algorithm MATLAB code and demo
  • Holte and Talley, 2009 (JTECH paper on the algorithm)
  • de Boyer Montégut et al., (2004) MLD climatology
  • Send James Holte an email if you need more information or have questions or comments.

    Funding from the National Science Foundation (OCE-0327544 to L. Talley and T. Chereskin), and U.S. Argo through NOAA (Grant NA17RJ1231 to SIO-JIMO, D. Roemmich) © 2016 Scripps Institution of Oceanography, UC San Diego. All Rights Reserved.