ICOADS 2 Degree

Due to a format switch from ASCII to BUFR on November 1, 2016 for drifting buoys, many reports were not processed for November. NCEP was able to recover many of the BUFR data, but NCEI was unable to fulfill gaps with its stream. This left the November files short of their normal number of drifting buoy reports, affecting downstream ICOADS users. Some reports will be recovered at a later date and a reprocess will be needed. This could take place in January or February and coordination between NCEP, NCEI, NCAR will be needed. December 2016 data is back to normal numbers and no issues are expected from that data month.

Brief Description:

  • The International Comprehensive Ocean-Atmosphere Data Set (ICOADS) is the most extensive collection of surface marine data spanning the past three centuries, together with simple gridded monthly summary products extending from 1800 forward.

Temporal Coverage:

  • Monthly values for 1800/01 - 2014/12.
  • Preliminary monthly values for 2015/01 - 2018/10 .
    IMPORTANT: The time period of these products is defined in two segments.
    1. Release 3.0 1800 through 2014
    2. Following the Release 3.0 end date data are based exclusively on blended NCEP-NCEI near-real-time GTS data with minimal quality control. These data should be considered preliminary and will be subject to change in new releases.

Spatial Coverage:

  • 2.0 degree latitude x 2.0 degree longitude global grid (90x180).
  • 89.0N - 89.0S, 1.0E - 359.0E.
Latest available data: Click to Enlarge


  • Sea Surface

Update Schedule:

  • Irregular (dependent on project resources and data availability considerations)
  • Monthly (preliminary segment)

Download/Plot Data:

Variable Statistic Level Download File Create Plot/Subset
Sea Surface Temperature (S) Multiple Surface sst.*.nc plot
Air Temperature (A) Multiple Surface air.*.nc plot
Scalar Wind (W) Multiple Surface wspd.*.nc plot
U-wind (U) Multiple Surface uwnd.*.nc plot
V-wind (V) Multiple Surface vwnd.*.nc plot
Sea Level Pressure (P) Multiple Surface slp.*.nc plot
Cloudiness (C) Multiple Surface cldc.*.nc plot
Specific Humidity (Q) Multiple Surface shum.*.nc plot
Relative Humidity (R) Multiple Surface rhum.*.nc plot
Sea-air Temperature difference (S-A) Multiple Surface smina.*.nc plot
Sensible Heat Parameter ([S-A]*W) Multiple Surface sflx.*.nc plot
Sat Sp Hum at SST minus Sp Hum (Qs-Q) Multiple Surface qsminq.*.nc plot
Latent Heat Parameter ([Qs-Q]*W) Multiple Surface lflx.*.nc plot
U-wind Stress (U*W) Multiple Surface upstr.*.nc plot
V-wind Stress (V*W) Multiple Surface vpstr.*.nc plot
Sensible Heat Trans Eastward Param (U*A) Multiple Surface uairt.*.nc plot
Sensible Heat Trans Northward Param (V*A) Multiple Surface vairt.*.nc plot
Latent Heat Trans Eastward Param (U*Q) Multiple Surface uspeh.*.nc plot
Latent Heat Trans Northward Param (V*Q) Multiple Surface vspeh.*.nc plot
Zonal Latent Heat Parameter (U*[Qs-Q]) Multiple Surface ulflx.*.nc plot
Meridional Latent Heat Parameter (V*[Qs-Q]) Multiple Surface vlflx.*.nc plot
Scalar Wind cubed (W*W*W) Multiple Surface wspd3.*.nc plot

Variable Statistic Level Download File Create Plot/Subset
Multiple First Sextile Surface *.sextile1.nc plot
Multiple Third Sextile (Median) Surface *.sextile3.nc plot
Multiple Fifth Sextile Surface *.sextile5.nc plot
Multiple Mean Surface *.mean.nc plot
Multiple Number of Observations Surface *.nobs.nc plot
Multiple Standard Deviation Surface *.stddev.nc plot
Multiple Mean Day of Month of Observations Surface *.mean_day.nc plot
Multiple Fraction of Observations in Daylight Surface *.day_fraction.nc plot
Multiple Mean Longitude (Off SW Corner of Box) of Observations Surface *.mean_lon.nc plot
Multiple Mean Latitude (Off SW Corner of Box) of Observations Surface *.mean_lat.nc plot

Usage Restrictions:

  • None

Detailed Description:

  • The netCDF files are subdivided into "standard" and "enhanced" products, which reflect the "trimming" (quality control) procedure used and the data mixture. In the standard products, the data have been edited using climatological 3.5 standard-deviation (sigma) limits, with the observations limited (as nearly as practical) to those from ships. In the "enhanced" products, in contrast, the data have been edited using broader 4.5 sigma limits to better represent extreme climate events, with observations from ships plus from other in situ marine platform types (e.g., drifting and moored buoys).

    Please refer to the ICOADS Website for more information about the ICOADS project, observational and summary products, and associated metadata.


  • Small numerical biases in previous netCDF files are described here.

Related File Naming & Structure Information:

File Names:

  • var.stat.nc   (In directory: /Datasets/icoads/2degree/)

Dataset Format and Size:

  • PSD standard NetCDF >80 Mbyte file for each global file (packed).
  • PSD standard NetCDF >161 Mbyte file for each global wspd3 file.

Missing Data:

  • Missing data is flagged with a value of 32766s.
  • Missing data is flagged with a value of -9.96921e+36f.


  • Please note: If you acquire ICOADS data products from PSD, we ask that you acknowledge us in your use of the data. This may be done by including text such as ICOADS data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd/ in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSD to justify keeping the ICOADS data set freely available online in the future. Thank you!


Original Source:

  • Multinational. The US contribution is the result of a cooperative project between the National Oceanic and Atmospheric Administration (NOAA)--specifically its Earth System Research Laboratory (ESRL), its National Centers for Environmental Information (NCEI), and the Cooperative Institute for Research in Environmental Sciences (CIRES), conducted jointly with the University of Colorado--and the National Science Foundation's National Center for Atmospheric Research (NCAR).


  • NetCDF questions:

    Physical Sciences Division: Data Management
    325 Broadway
    Boulder, CO 80305-3328
  • Data questions:

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