Argo world 

Why is Argo data novel?

As a worldwide array of 3200 floats, Argo data is unique for several reasons:

  • The distribution of data throughout the oceans is uniform rather than dependent on shipping lines.
  • There is a of lack of seasonal bias since the floats operate year round.
  • The efficient data management network that provides free automatic quality controlled data within 24 hours and scientifically quality controlled, delayed mode data within a year.
  • Multi-national collaboration to deploy, monitor and analyze floats and their data.
The following table summarizes some novel parts of Argo's data set:

Observation type
Number per year
Max Depth
Geographical restriction
Ship-based temperature and salinity
T + S
5000 (to 1000m)
Full water depth
• Limited by ship endurance
(100 per month)
• Few at high latitude in winter
• Typically along lines
Expendable XBT from merchant ships
• Along shipping routes
• Avoid high latitude in winter
• Many areas unsampled
T + S
42,000 (May 2004)
120,000+ (2015)
• Ice free areas deeper than 2000m

Argo Floats

density map
Argo achieved global coverage in the open ocean at the target of 3° x 3° density near the end of 2007. In 2016, Argo has extended its area of coverage to include marginal seas and seasonal ice zones, pushing the target number of floats to 3800.

World Ocean Database 2009

The World Ocean Database contains 500,000+ profiles deeper than 1000m from the 20th century onwards.
Argo has 100,000+ profiles per year since 2012.

Ship Based CTDs during WOCE and GO-SHIP

ctd-oceanus-s WOCE-O-T

WOCE 1990 - 1998


GO-SHIP 2007 - current

In 8 years, the WOCE Hydrographic survey collected data from about 30,000 CTD stations mostly along the sections shown here.
GO-SHIP maintains 61 lines with most lines repeated each decade.

Ship based XBTs

XBT ship XBT auto launcher XBT countries
XBT lines are completed on ships of opportunity. Lines are repeated 4 times a year for high density lines and 18 times per year for frequently repeated lines. Note poor coverage in southern hemisphere.