Funding for this TPOS-2026 mission is provided by NOAA OMAO UxSOC in support of the project "Uncrewed Surface Vehicles (USV) Integrated within the Tropical Pacific Observing System (TPOS) - TPOS Equatorial Pacific Experiment (TEPEX) Process Studies Embedded Within Backbone Monitoring".

Mission Overview

Mission Dates: Mission Underway

TPOS-2026 (Mission 8)

Mission Blog

This Blog is our Logbook

September 15, 2026

My first research cruise was an 18 day cruise in 1984 on the R/V Endeavor for the Gulf Stream Dynamics Experiment. Prof. Randy Watts (URI/GSO) was the chief scientist and I was an undergraduate summer intern. I held the 12-4 AM and PM watch along with a senior engineer and the lab’s data manager. We had a log book and Randy insisted that every watch had to log whatever happened, even if it was a seemingly non-related fact like that there was a rowdy game of deck hockey using XBT caps as hockey pucks. His reasoning was that you can remember details of events better by wrapping them around the fun and interesting things that stick in your mind.

This Blog is our Logbook. We will log the decisions going into our mission routing and adaptive sampling. After the mission is done, I hope this log book will help us better curate the data, all of which is or will be publicly available.

With this Historic El Niño affecting people’s lives and plans, people are turning their attention to the tropical Pacific and we are getting some media attention. Here’s a link to an interview I gave on the Fox Weather Show last Friday (September 11, 2026): https://www.foxweather.com/watch/fmc-vq0dfltnxxhtjp9n.

 

I hope this blog reaches a broad audience, including learners of all ages, who might find our Blog interesting and follow us as we have these uncrewed surface vehicles sail their way to the source of all that weird weather. The saildrones have a long journey – it’s over 1000 nautical miles from Hawaii to the equator and they are moving at about 1.7 knots (1 knot = 1 nm/hour. You can walk this fast!). Even the most seasoned tourist might not have visited the Intertropical Convergence Zone (ITCZ) or the equatorial cold tongue. We are almost at our next Way Point. So stay tuned.

Blog post by Meghan Cronin

Sailing between Hurricanes to Dodge Damaging Winds and Waves

September 4, 2026

The TPOS Saildrone USVs are underway to Ground Zero of the current El Niño that is now predicted by NOAA to have a 90% chance of becoming a very strong event and a 69% chance of becoming an historic event exceeding the strength of previous El Niños dating back to 1950. However, the first pair of TPOS USVs launched from Honolulu were forced to divert from their equatorward course by 180 nautical miles to avoid Category 4 Hurricane Lowell. Unlike the USVs used for NOAA’s hurricane observations, the TPOS USVs are built for speed and endurance and are not designed to sustain hurricane force winds and sea states. With an averaged speed of 1.8 kt and maximum speed of up to 5.5 kt during the diversion, TPOS USV SD1033 and SD1077 braved 36 kt winds and 14.8 ft waves. They are now back on course, together with SD1088 and SD1090, navigating through the hurricanes shown in the figure below. It is highly unusual to see three hurricanes in the eastern Pacific at the same time. More Pacific hurricanes are just one of the major impacts El Niño has on weather around the globe.

 

TPOS USVs SD1077 and SD1033 (shown under SD1077), were forced to divert from their equatorward course to avoid Hurricane Lowell, which is now accompanied by Hurricanes Karina and Marie. Hurricane Lowell is forecast by NOAA’s National Hurricane Center to turn northward, maintaining major hurricane strength, as shown by the red track with arrows. Our thoughts are with Hawaii residents, wishing them safety through the more active hurricane season during this El Niño.

Figure background: Saildrone, Inc. Mission Management portal with predicted winds from NOAA’s Global Forecast System on September 2. Yellow diamonds mark the locations of NOAA National Data Buoy Center fixed moorings. TPOS USV tracks, shown in blue and green, and the operating area east of the 140°W TAO moorings are for illustration purposes only. Exact tracks will be adjusted in real time to adaptively observe the developing El Niño once the USVs reach the equatorial Pacific.

Blog post by Dongxiao Zhang

Heading to Ground Zero!

August 31, 2026

We now have two pairs of Saildrone, Inc. Uncrewed Surface Vehicles (USV) heading to the Nino 3.4 region of the central equatorial Pacific – Ground Zero of the large El Niño that is in the news. The first pair of USV left Honolulu over a week ago on August 21, 2026, and the second pair is leaving today (August 31, 2026). Each pair of saildrones has an ASVCO₂^® for monitoring air-sea flux of CO₂ and ocean acidification; and all four saildrones have an ADCP to measure upper ocean currents and a full suite of Meteorological and Ocean (METOC) sensors to measure wind stress and air-sea heat flux, and sea surface temperature at multiple depths from the skin of the ocean down to the bottom of the hull at 2 m depth. That 2-meter sensor also measures salinity and dissolved oxygen. In addition, the METOC suite for all but one drone (#1080) has a fluorometer to measure chlorophyll, which is an indicator for phytoplankton in the water.

An El Niño is declared when surface water in the Niño 3.4 box is 0.5°C warmer than the background temperatures for an extended period. These anomalously warm surface waters cause cloud and wind patterns to shift, changing weather around the world. Our 4 drones will head down to the equator to map out exactly where this warm water is located, how sharp the fronts are, how the fronts and warm water affect ocean heating of the atmosphere, how the clouds feedback by affecting how much sunshine enters the ocean, and their impacts on and relation to winds and currents. Our hope is that these measurements will help improve forecasts of this El Niño – by constraining the numerical models with direct measurements, and by cluing us into whether our numerical models are capturing processes that cause the El Niño to grow, evolve, and eventually transition to either a normal or La Niña state. We also will use these observations to help quantify the impact of this El Niño on the ocean’s uptake of carbon dioxide. Normally, the central and eastern equatorial Pacific is a region of carbon dioxide outgassing. But during an El Niño, this is disrupted. By how much? We will see.

Please join us as we journey to the equator for an up close look at this historic El Niño. We are looking forward to observing some really interesting ocean and atmosphere interactions during the next four months. For more information on El Niño and Niño 3.4 see: https://www.noaa.gov/understanding-el-nino and https://www.ncei.noaa.gov/access/monitoring/enso/sst.

TPOS-2026 planned mission route overlaid on satellite image of anomalously warm sea surface temperatures in the Nino 3.4 box. Satellite image from https://www.noaa.gov/understanding-el-nino (Courtesy NOAA).

Blog post by Meghan Cronin