OS Research

A Record-Breaking Indian Ocean Dipole: What Happened in 2021–2022?

Ankur Srivastava February 5, 2026

Left panel: The monthly Dipole Mode index (DMI), the Niño 3.4 index, and the relative Niño 3.4 index (RONI) from observational SST datasets: ERSST (bars), and the three-month running mean for ERSST, OISST and HadlSST (lines) for the period 2020–2022; Right Panel: A schematic illustrating the La Niña-induced anomalous Walker circulation over Indian longitudes, and the associated modulation of surface winds, Wyrtki jets and the anomalous heat content in the eastern tropical Indian Ocean.

The Indian Ocean Dipole (IOD) is generally considered a seasonal mode of variability, developing and decaying within a single year. During 2021–2022, however, negative IOD conditions persisted for approximately 19 months (Figure 1, top left), making this event the longest—and among the strongest—observed since reliable records began. This unusual persistence highlights important aspects of ocean–a ...[Read More]

How do mesoscale eddies modulate CO2 fluxes in the Southern Ocean?

Mariana Salinas Matus January 23, 2026

Mesoscale eddies and Southern Ocean carbon sink The Southern Ocean takes up more than a quarter of the anthropogenic CO₂. Its powerful westerly winds, deep overturning circulation, and intense mixing make it a major player in Earth’s climate system. But beneath this large-scale picture lies a world of swirling, dynamic structures that constantly reshape the ocean’s physical and biogeochemical prop ...[Read More]

Monitoring the Ocean’s Green Pulse: A New Global Dataset for Phytoplankton Phenology

Sandy Thomalla June 10, 2025

Summer phytoplankton bloom in the Baltic Sea (Credit: NASA Earth Observatory images by Joshua Stevens and Lauren Dauphin, using Landsat data from the U.S. Geological Survey and MODIS data from LANCE/EOSDIS Rapid Response).

Phytoplankton are tiny, single-celled organisms mainly found in the ocean’s sunlit surface, where they grow through photosynthesis, forming the marine food web’s base and regulating Earth’s climate by absorbing carbon dioxide. Their seasonal growth cycles—known as “blooms”—drive marine productivity and influence everything from carbon uptake to food security. But how can we track ...[Read More]

Sailing for Science: How Data from Sailing Races Advances Ocean Research

Jacqueline Behncke November 12, 2024

The tracks of the 33 competitors from the last Vendée Globe sailing race edition in 2020-21. (Credit: Erwan Rivault)

The Vendée Globe began on November 10th, with 44 participants embarking on the world’s toughest sailing race. This non-stop, single-handed round-the-world yacht race challenges skippers to circumnavigate the Southern Ocean. The race starts in France, traverses the North Atlantic, and heads directly into the Southern Ocean. Despite taking place during the austral summer, the conditions remain ...[Read More]