Prioritize...
Upon finishing this page, you should be familiar with major buoy deployment programs (such as the Global Drifter Program and TAO Buoys), and recognize why close encounters between stationary ocean buoys and tropical cyclones are "lucky" encounters, especially over open ocean waters (away from coastal areas). You should also be able to interpret data summary plots from the TAO / TRITON Buoy Array.
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You're already familiar with the in-situ weather observations on land that forecasters have available to them. While land-based surface observational networks have gaps, those gaps are nothing like the gaps that exist in observational networks over the oceans, and the oceans constitute a large part of the tropics! For forecasters tracking tropical cyclones, that means that considerable time may pass between any in-situ observations in or around a particular storm, and some storms may never be sampled directly by an in-situ observation. Sometimes tropical cyclones "find" tiny islands scattered about the oceans, providing in-situ observations like the pressure trace below, from when the eye of Category 5 Hurricane Irma passed directly over a National Ocean Service observation platform on the coast of Barbuda in 2017.
The pressure trace is striking, with pressure plummeting down to 27.2 inches of Mercury (921 millibars) as the eye passed, before rapidly recovering. But, a direct encounter of a hurricane's eye with a stationary, in-situ observation site are rather infrequent in the tropics. Out over the oceans, if a tropical cyclone doesn't pass over an island with an observation site, forecasters are limited to the available buoy and ship observations. Many storms miss these observations, however. To see what I mean, check out the image below from the website for the National Data Buoy Center, which shows the locations of buoys (and oil-drilling platforms that collect observations) across much of the North Atlantic. While the East Coast and Gulf Coast of the U.S. seem fairly well sampled by observation sites (though if we zoomed in more, we would see some gaps), farther out over remote ocean waters, a tropical cyclone finding a buoy is akin to finding a needle in a haystack. The buoys over the Atlantic and other oceans around the world are widely spaced, leaving huge gaps of hundreds or thousands of miles between buoy observations.
Every now and then, a tropical cyclone will have a "lucky" direct encounter with a buoy, much like Hurricane Irma's encounter with the observation site on the Island of Barbuda, but it's somewhat rare, especially away from the coasts. The relative wealth of buoy observations along the coasts of the United States is augmented by the Coastal-Marine Automated Network (C-MAN), which was developed by the National Data Buoy Center in the early 1980s to better maintain weather observations near the coasts. C-MAN buoys provide crucial observations in coastal areas, particularly when tropical storms and hurricanes approach the East Coast and Gulf Coast states.
Another special buoy program that you should be aware of is the Tropical Atmosphere Ocean (TAO) project, which covers the equatorial Pacific (see image below). TAO buoys have since been combined with buoys from the Japanese TRITON (Triangle Trans Ocean Buoy Network) project to create the TAO / TRITON array, which contains several dozen buoys. As an aside, the TAO / TRITON array has a pretty interesting history, which you can read about in the Explore Further section below, if you would like. Data from the TAO / TRITON array are instrumental in detecting El Niño (opens in a new window) and La Niña (opens in a new window) conditions, which as you'll learn later, can have major impacts on global weather patterns. You can see the locations of the TAO buoys in the image below.
On the TAO / TRITON Web site (opens in a new window), you can access summary plots from individual buoys like this sample summary plot (opens in a new window) from the TAO buoy located at 5 degrees North latitude and 170 degrees West longitude. This summary, which spans from January through May 2026, represents a running five-day mean of wind vectors, elevation of sea level (not counting ocean waves) and temperatures from the sea surface to a depth of 300 meters. When you looked at the plot, you may have noticed that sea level in the vicinity of this buoy is not flat (it varied by almost 25 centimeters, or 10 inches, during this time), nor does it correspond to an elevation of zero. We'll talk more about variations in sea-surface height in a later lesson.
Keep in mind that the data in the top part of the graph shows wind vectors (even though there are no arrowheads like we would usually see on a vector). While standard meteorological convention is to plot and express wind direction as the direction from which the wind blows, since the red slashes are vectors, they extend outward and point in the direction that the wind is blowing toward (exactly the opposite of the standard convention). So, for example, during April and May on this graph, winds predominantly blew from the northeast (toward the southwest) at this buoy. By the way, the length of the red slash indicates the wind speed (in meters per second).
We'll return to data from the TAO / TRITON array later on when we cover El Niño and La Niña, but I wanted you to be aware of the TAO / TRITON project since it's an important component of the system of buoys that monitors tropical weather. Even with special buoy programs, however, the overall picture should be crystal clear to you by now -- stationary ocean buoys simply can't cover the entirety of tropics, and they leave lots of gaping holes in our observing system. Fortunately, data from other buoy programs that aren't stationary can act as a supplement.
One such program is the Global Drifter Program (opens in a new window) (GDP), under the auspice of the Atlantic Oceanographic and Meteorological Laboratory (AOML), which sometimes deploys drifting buoys in the paths of hurricanes, giving forecasters access to crucial surface weather data. NOAA is also increasingly partnering with private companies to deploy buoys ahead of tropical cyclones. In the image on the right, you can see locations of buoys that were deployed ahead of Hurricane Helene in 2024 from a combination of public and private sources.
Another useful program for monitoring tropical ocean conditions is the Argo Program (opens in a new window). Argo deployments began in 2000 and at any given time, the fleet consists of roughly 4,000 robotic "floats" which drift around with the ocean currents, monitoring upper ocean conditions (temperature and salinity) from the surface down to a depth of 2,000 meters. Argo floats can dive and rise to different depths to gather a complete vertical profile, but keep in mind that they do not collect any atmospheric observations (they only measure water conditions). Still, the data they collect, which get assimilated into computer models, can help monitor changes to temperatures in the top layer of the ocean, helping to improve tropical cyclone forecasts. Because they drift around with the ocean currents, their sampling of the ocean can be somewhat "uneven," meaning that some areas may end up with a lot of floats at any given time, while other areas end up with too few.
NOAA also maintains a number of hurricane gliders (opens in a new window), which are remote-controlled underwater vehicles which measure temperature, salinity, and pressure (among other variables) from the surface all the way down to a depth of 1,000 meters. These gliders move slowly (horizontally), so they can't really follow hurricanes around, but they can sample well-known ocean features (like warm currents) that are known to impact hurricane intensity. Data from these gliders gets incorporated into model forecasts, so they provide critical data about the changing thermal profiles in the ocean.
Finally, NOAA also partners with private companies to deploy "uncrewed surface vehicles (opens in a new window)" (USVs) into tropical cyclones the Atlantic. USVs aren't actually buoys, but instead are essentially remote-controlled sailboats capable of measuring winds, air and water temperatures, pressure, and wave heights, among other variables. Since 2021, these USVs, which have been constructed to withstand the fierce conditions inside a hurricane, have sailed missions into select hurricanes, collecting critical data that is transmitted to the National Hurricane Center in real-time, as well as assimilated into computer model forecasts. Unfortunately, public availability of real-time data from private buoy or USV deployment can be somewhat limited, but I have some links below in the Explore Further section below that you can use to track the available data from various public programs.
Even with special buoy and USV programs to observe tropical cyclones, however, our in-situ observing networks for surface observations over the oceans just aren't enough to get a full picture of what's going on in the tropics (or within tropical cyclones) at all times. Therefore, forecasters must rely on other data sources to get a more complete picture of the state of the tropics. We'll start our investigation of those other sources by looking into the role that aircraft observations play in observing weather in the tropics (particularly when tropical cyclones are present). Read on.
Explore Further...
Data Resources on the Web
Looking for real-time data from buoys and ships? You may be interested in the following resources:
- Decoded Offshore Weather Data (opens in a new window) is perhaps the most straightforward for accessing observations from ships and moored buoys in the vicinity of tropical cyclones. If you check-out "Tropical Cyclone/Hurricane Maps," you'll see the worldwide list of current or recent tropical cyclones. Simply click on the name of the tropical cyclone to access buoy and ship observations in the vicinity of the cyclone (though you'll often find that these observations are sparse). The labels (two digits and a letter) used for unnamed storms follow the standards you learned about previously.
- National Data Buoy Center (opens in a new window) has an interface with a wealth of stationary buoy observations, as well as ship observations (opens in a new window). The page often highlights the nearest available observations when tropical cyclones are present.
- The CIMSS tropical cyclones (opens in a new window) site also allows you to view buoy and ship observations in the vicinity of tropical cyclones. Just click on any particular active storm, and in the interface that pops up, select "buoy" and / or "ship" to view any nearby observations (though these will often be sparse). We'll learn about many of the other available fields later in the course.
- Current positions of drifting buoys in the Global Drifter Program (opens in a new window) along with recent data they've collected. They also have an archive of deployments by year (opens in a new window).
- Argo Float data and recent trajectories (opens in a new window)
- AOML Ocean Observations Viewer (opens in a new window)has a wide variety of data from gliders, floats, buoys, and USVs in a single interface.
- Information on USV missions into hurricanes (opens in a new window), including blogs from missions in recent years and links to publicly available data (usually after the event).
For History Buffs
As you just learned, the TAO / TRITON array provides critical monitoring that helps forecasters measure El Niño and La Niña, and predict their onset. The development of the program was motivated by the historic 1982-83 El Niño, which was the strongest on record at the time. And, at the time, forecasters didn't even know about the El Niño until it was near its peak! The impacts of El Niño that rippled through the atmosphere were far-reaching -- droughts and fires in Australia, Southern Africa, Central America, Indonesia, the Philippines, South America and India, as well as serious floods in the United States, Peru, Ecuador, Bolivia and Cuba. Globally, roughly 2,000 deaths were credited to weather events that were influenced by El Niño. We'll explore the connections between El Niño, La Niña, and global weather patterns in a later lesson.
The great devastation caused by the weather during the 1982-83 El Niño underscored the need for a real-time monitoring system for the tropical Pacific, to better detect and eventually predict the onset of El Niño and La Niña events. Thus, the foundation of what would become the TAO / TRITON array was laid in 1984 when a series of buoys was field tested along 110 degrees West longitude in the equatorial Pacific, and the rest is history. In the 2010s, the project fell on hard times due to a lack of funding, but it was reinvigorated with an upgrade in the mid-2020s (opens in a new window).