NOAA sends Saildrones to investigate the engine driving El Niño in the equatorial Pacific

    Uncrewed surface vehicles, marine drones, will help scientists monitor the development of a historically strong event, the 2026–2027 El Niño, across the Pacific.

    An orange Saildrone drone travels across a bay with a mountain in the distance. The Saildrone Explorer SD-1090 departed Honolulu on 21 August 2026 for a four-month mission to the equatorial Pacific, 2,400 kilometres to the south. Four Saildrones will collect ocean and atmospheric data for scientists at NOAA's Pacific Marine Environmental Laboratory. Photo courtesy of Saildrone.
    An orange Saildrone drone travels across a bay with a mountain in the distance. The Saildrone Explorer SD-1090 departed Honolulu on 21 August 2026 for a four-month mission to the equatorial Pacific, 2,400 kilometres to the south. Four Saildrones will collect ocean and atmospheric data for scientists at NOAA's Pacific Marine Environmental Laboratory. Photo courtesy of Saildrone.

    On 21st August 2026, two orange Saildrone Explorer uncrewed surface vehicles departed Honolulu, Hawaii, bound for a vast and remote area of the eastern Pacific Ocean where a historic El Niño event is gaining strength.

    Equipped with an array of specialised meteorological and oceanographic sensors, the two orange wind-powered vessels will join two other Saildrones launched the previous week on a 9,700-km round trip mission for NOAA's Pacific Marine Environmental Laboratory (PMEL).

    They will travel 2,400 km south to the centre of the developing El Niño event, where a huge amount of heat that was previously confined to the western Pacific has shifted eastwards and is now being released into the atmosphere, altering weather patterns around the world.

    “An El Niño of epic proportions is on the way,” said Michael McPhaden, a former senior scientist at PMEL who now works at NOAA's Cooperative Institute for Climate, Ocean, and Ecosystem Studies (CICOES). “We're going to take a closer look at it.”

    Data to deepen understanding

    Once there, the Saildrones will follow a series of routes through the Tropical Pacific Observing System, a multinational network of moored surface buoys that collect data and provide continuous, real-time monitoring of surface winds, air temperature, humidity and upper-ocean temperatures down to 1,640 feet, as well as Argo profiling floats that collect ocean profiles down to a depth of 2 kilometres every 10 days.

    Drifting buoys are distributed throughout the network, measuring sea surface temperatures and currents. From above, satellites track the buoys and capture surface observations across wide areas.

    Four uncrewed surface vehicles equipped with instruments were deployed from Hawaii to the equatorial Pacific Ocean in August to monitor the increasing intensity of El Niño. Credit: Pacific Marine Environmental Laboratory
    Four uncrewed surface vehicles equipped with instruments were deployed from Hawaii to the equatorial Pacific Ocean in August to monitor the increasing intensity of El Niño. Credit: Pacific Marine Environmental Laboratory

    During the four-month mission, the Saildrones will collect data at one-minute intervals, spaced several hundred metres apart, obtaining additional information between existing ocean sensors.

    The data they collect allow scientists to define the boundaries or fronts between warm tropical waters and the normally cooler waters to the east along the equator, as well as compare observations captured by satellites, moored buoys, floats and other autonomous platforms to ensure consistency.

    “Satellites are excellent for obtaining wide-area coverage,” said research oceanographer Meghan Cronin, leader of the Saildrone project at PMEL. “But you still need to put a thermometer in the water to ensure an accurate measurement. Saildrones carry a complete set of additional sensors that allow us to measure heat exchange between the ocean surface and the atmosphere, as well as changes resulting from ocean CO₂ outgassing and uptake, as we cross ocean fronts near the equator.”

    Previously, deploying that thermometer and the sensor package in the middle of the ocean required months of planning, the availability of large specialised research vessels and teams of scientists spending months at sea, all of which is expensive.

    This infographic shows the different platforms that make up the Tropical Pacific Observing System. The Tropical Pacific Observing System monitors ocean conditions in the equatorial Pacific using satellites and various fixed and autonomous platforms. Credit: Pacific Marine Environmental Laboratory
    This infographic shows the different platforms that make up the Tropical Pacific Observing System. The Tropical Pacific Observing System monitors ocean conditions in the equatorial Pacific using satellites and various fixed and autonomous platforms. Credit: Pacific Marine Environmental Laboratory

    Driving a new era in ocean observation

    Since 2001, NOAA has dramatically increased its use of uncrewed systems for oceanographic research, not only because they reduce or eliminate risks to human safety, but also because they can collect highly accurate data at a fraction of the cost of traditional research expeditions and fill gaps in existing networks, operating for months without rest or refuelling.

    El Niño occurs in two main “types”, which differ primarily in where anomalous ocean warming occurs and how it affects global weather patterns. During an eastern Pacific El Niño, such as the one currently developing, warming is strongest in the eastern equatorial Pacific and off the coast of South America. This fundamental redistribution of heat and storms alters the jet stream, causing weather disruptions around the world, such as severe droughts in Australia and heavy rainfall or flooding in the southern United States.

    Typical changes in weather patterns experienced around the world during the peak of El Niño. Credit: NOAA-NWS
    Typical changes in weather patterns experienced around the world during the peak of El Niño. Credit: NOAA-NWS

    Data to benefit current and future forecasts

    During this mission, in addition to standard measurements, the Saildrones will capture observations of various small-scale processes (such as equatorial upwelling and intense air-sea interactions associated with ocean fronts) that cannot be accurately detected by the buoy, glider or satellite network. These processes often lead to the explosive development of large storm systems and individual storms that can influence the movement of warm water and the development of El Niño.

    Some of the data will be transmitted via the Global Telecommunications System (GTS) to operational forecasting centres in real time, with the main goal of allowing the field campaign to help scientists better understand these air-sea interactions and systematically improve NOAA's global and US operational weather forecasts.


    Two Saildrones are equipped with an autonomous surface-vehicle carbon dioxide detection system. The sensor is a specialised instrument developed by PMEL that captures automated, high-precision measurements of carbon dioxide pressure at the boundary where the ocean meets the atmosphere. All of them are also equipped with acoustic Doppler current profilers, hydroacoustic devices that measure the speed and direction of water movement in the upper 250 feet of the water column.

    “Long-range, remotely piloted uncrewed surface vehicles are opening a new era of ocean observation by focusing on areas where data are most needed to improve our understanding and forecasts of rapidly developing, high-impact air-sea processes such as this El Niño, which will have profound effects around the world,” said Dongxiao Zhang, principal investigator of this project at CICOES.

    Source: NOAA