Argo

Argo. Argo is a global, international ocean observation system that uses a fleet of autonomous profiling floats to collect data on the temperature and salinity of the upper ocean. The program, named after the mythical ship Argo and the Jason ocean satellite series, represents a cornerstone of modern physical oceanography. Its data are essential for understanding ocean climate, improving weather forecasting, and monitoring long-term changes in the Earth's climate system.

Overview

The program operates a network of nearly 4,000 robotic instruments, known as Argo floats, which drift with ocean currents at a depth of approximately 1,000 meters. On a pre-programmed cycle, typically every ten days, these floats ascend to the surface, measuring the water's properties throughout the water column. Upon surfacing, each float transmits its collected data, including its position via the GPS, via satellite to data centers for immediate public dissemination. This real-time data system is integrated into major operational centers like the European Centre for Medium-Range Weather Forecasts and the National Oceanic and Atmospheric Administration. The overarching goal is to maintain a sustained, systematic observation of the global ocean's interior, filling a critical gap left by traditional ship-based measurements.

History and Development

The concept for Argo was developed in the late 1990s by an international team of oceanographers, notably including scientists from the Scripps Institution of Oceanography and the Woods Hole Oceanographic Institution. It was designed to complement the emerging satellite altimetry missions, such as TOPEX/Poseidon, by providing the subsurface data needed to interpret sea surface height measurements. A major pilot project, supported by agencies like the National Science Foundation and NASA, demonstrated the feasibility of the float technology and data system. The full global array was declared complete in 2007, achieving its initial target of 3,000 floats. Since then, the network has been sustained and enhanced through continuous international contributions, with leadership from bodies like the Intergovernmental Oceanographic Commission.

Scientific Objectives and Design

The primary scientific objectives are to quantify the ocean's role in climate variability and change, including the storage and transport of ocean heat content, and to provide data for initializing and validating climate models. The standard Argo float is designed to operate autonomously for four to five years, powered by lithium batteries, and measures fundamental variables: temperature, conductivity (for salinity), and pressure. The core "Core Argo" mission focuses on these physical parameters down to 2,000 meters depth. A key innovation in the program's design is its completely open data policy, with all measurements made publicly available within 24 hours of collection, adhering to principles set by the Global Climate Observing System.

Data and Discoveries

The dataset, archived at designated centers like the Coriolis data center in France and the Global Drifter Program office, has revolutionized understanding of the oceans. Key discoveries include detailed mapping of global ocean warming patterns, providing unequivocal evidence that over 90% of the excess heat trapped in the Earth system is stored in the ocean. The data have precisely quantified changes in the global hydrological cycle through salinity variations and have revealed critical details about phenomena like the Atlantic meridional overturning circulation and El Niño. The observations are also fundamental for operational oceanography, directly improving the accuracy of seasonal forecasts produced by institutions like the Met Office.

International Collaboration

Argo is a model of international scientific cooperation, involving over 30 nations that contribute floats, ship time, and funding. Coordination is managed by the Argo Steering Team and the Argo Data Management Team, under the auspices of the Intergovernmental Oceanographic Commission and the World Meteorological Organization. Participating countries include the United States, France, Japan, Australia, India, and the United Kingdom, with major contributions from agencies such as NOAA, the European Space Agency, and the Japan Agency for Marine-Earth Science and Technology. This collaborative framework ensures the network's maintenance and evolution, including new missions like Deep Argo for sampling abyssal depths and Biogeochemical Argo to monitor chemical and biological parameters.

Category:Oceanography Category:Climate change assessment and attribution Category:International scientific organizations