Argo is a major  international ocean observing program that uses profiling floats to observe temperature, salinity, currents and biogeochemical parameters in the first 2,000 meters of the earth’s oceans. Since the early 2000s, the Argo profiling floats dcollect real-time data that is used in climate and oceanographic research. Today, more than 4,000 floats are active in the world’s oceans,  gathering measurements down to 2,000 meters below the sea surface.

CLS services for the Argo program

CLS provides Argos and Iridium satellite telemetry services for most of these oceanographic instruments and special data hosting services for floats using Iridium RUDICS communication.

Once a year, the data managers of the international Argo program come together to discuss technical matters pertaining to the Argo data stream. This year was the 19th Argo Data Management Team meeting, hosted by Scripps Institution of Oceanography from December 2-7, 2018.

CLS attended this meeting to present the results of validation of profiling floats with satellite data from AVISO.

Validate Argo float data through comparison with altimeter observations

In order to quality control Argo float data, CLS, global expert in altimetry data, developed an algorithm to intercompare dynamic height anomalies (DHA) measured by Argo floats and altimeters. Argo floats time series are from the Coriolis GDAC and sea level anomalies (SLAs) are from AVISO multi-missions combined maps that are co-located in time and space to each Argo measurements.

Results show very good consistency between collocated SLA and DHA for the majority of profiling floats with quite stable agreement this year relative to the last years.

Every three months, this intercomparison allows CLS to identify anomalies in the dataset.

When this occurs, CLS notifies the Primary Investigator so that the faulty instruments can be corrected, and the erroneous data removed from operational weather and climate applications.

SLA Argo data
The figure on the left shows the trajectory of Argo float 1901713. CLS estimates a sea level anomaly from the Argo float measurements at each position and compares it with sea level anomaly measurements from satellite altimeters. In the graph on the right, there is good correlation between satellite and in-situ measurements. If there is too much variation, CLS notifies the PI and data is corrected or, if correction is not possible, removed from operational weather and climate applications.