{"id":5071,"date":"2026-10-28T10:27:13","date_gmt":"2026-10-28T10:27:13","guid":{"rendered":"https:\/\/hygeos.com\/?p=5071"},"modified":"2026-10-28T10:30:55","modified_gmt":"2026-10-28T10:30:55","slug":"new-cifre-phd-at-hygeos-ocean-color-retrieval-from-metop-sg","status":"publish","type":"post","link":"https:\/\/hygeos.com\/en\/new-cifre-phd-at-hygeos-ocean-color-retrieval-from-metop-sg\/","title":{"rendered":"New PhD: ocean color retrieval from MetOP-SG"},"content":{"rendered":"
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New PhD: ocean color retrieval from MetOP-SG<\/h1><\/div>

HYGEOS and the Laboratoire d\u2019Optique Atmosph\u00e9rique (LOA, University of Lille<\/a>) have launched a new CIFRE PhD, supported by the French Association Nationale de la Recherche et de la Technologie<\/a> (ANRT), to improve the observation of ocean color with Europe\u2019s new MetOp-SG satellites.<\/p>\n

The thesis is carried out by Pierre Posson, an ESTACA<\/a> engineer who completed his final-year internship at HYGEOS. It is supervised by J\u00e9r\u00f4me Riedi (LOA)<\/a> and Fran\u00e7ois Steinmetz<\/a> (HYGEOS), under the title: “Synergistic Atmospheric Corrections for Ocean Color Observation Using Multi-Angular Polarimetry from 3MI and the Spatial Resolution of METimage on Board MetOp-SG”<\/em>.<\/p>\n<\/div>

Why ocean color matters<\/strong><\/h3><\/div>

Seen from space, the color of the ocean reveals what the water contains: phytoplankton, sediments and dissolved organic matter. Phytoplankton feeds marine life and helps the ocean absorb CO\u2082. Monitoring it on a global scale is therefore essential to understand the carbon cycle and how the ocean responds to climate change.<\/p>\n

Near the coast, these observations also help monitor water quality: river discharge, eutrophication, and algal blooms that can be harmful or toxic.<\/p>\n

Satellites do not see the water directly. Between 80% and 95% of the light they measure comes from the atmosphere (molecules and aerosols) and from the sea surface, and the ocean signal is only a few percent of the total. Removing everything else is known as atmospheric correction. HYGEOS is a recognized expert in this field, with its Polymer<\/a> algorithm used to process data from many ocean color sensors.<\/p>\n<\/div>

State of the art<\/strong><\/h3><\/div>

The traditional approach estimates aerosols in the near-infrared, where the ocean is assumed to be black, and then extrapolates them to the visible. This assumption breaks down in turbid waters.<\/p>\n

More generally, current methods rely only on color, observed from a single viewing angle. Measuring polarization from multiple angles provides independent information: it characterizes aerosols far more precisely and better separates the atmosphere from the ocean. The POLDER and PARASOL missions<\/a>, followed by NASA\u2019s PACE mission<\/a> in 2024, have demonstrated this.<\/p>\n<\/div>

A unique opportunity with MetOp-SG<\/strong><\/h3><\/div>

The European MetOp-SG platform<\/a>, whose first satellite was launched in August 2025, brings together on a single satellite:<\/p>\n