A Day in the Life of the Ocean Currents

By Mara Freilich, Postdoctoral Fellow at the Scripps Institution of Oceanography. // ABOARD THE SALLY RIDE //

A whiteboard lists the day's schedule.
Schedule for the day. Credit: Mara Freilich

While doing oceanographic fieldwork, we live and work on the ship. This is the second week that we have been at sea. While there is a rhythm to life at sea, every day is different. Since we are studying ocean dynamics that change quickly, we sample adaptively, meaning that we adjust when and where we sample to follow quickly moving ocean features. I am a postdoctoral fellow at University of California, San Diego’s Scripps Institution of Oceanography. I am working on sampling biological communities to understand how ocean currents, particularly a type of current called submesoscale that spans up to 6.2 miles, or 10 kilometers, across, affect plankton, which form the base of the food web in the ocean. We work as a team on the ship, and I work most closely with the biological sampling team: Kelly Luis (NASA’s Jet Propulsion Laboratory), Sarah Lang and Pat Kelly (University of Rhode Island), Dante Capone (UC San Diego), and Élise Beaudin (Brown University).

There is no typical day, but here’s a look at one “day in the life” of the S-MODE field campaign.

Early morning: I woke up at 2:45 am this morning to plan biological sampling. We aimed to do a Conductivity, Temperature, and Depth (CTD) cast at 5 am. A CTD cast involves lowering a scientific instrument through the water that measures a range of physical and biological variables and that can close bottles to bring water from depth onto the ship. When I woke up, I learned that overnight, Sarah had spotted a submesoscale eddy  in the observations. I looked at the new data and agreed that this was exactly the type of ocean current we had been looking for and charted a course to cross through it again. Once I had the plan, I sent waypoints to the captain and mates who drive the ship. Elise, Kelly, Dante and I started sampling surface water to study the biological communities there. When we got the location that we had planned for a CTD cast, we sampled water from the cast and started a 24-hour experiment to measure growth and grazing rates. This allows us to investigate the role of ocean physics and community composition on ocean food webs. We finished processing the samples just in time for a breakfast of croissant and eggs.

Woman in teal shirt conducts Conductivity, Temperature, and Depth, or CTD, cast to preserve marine samples.
Mara Freilich preserving samples from the CTD cast. Credit: Kelly Luis

Late morning: After a quick nap, I did some data analysis. We are constantly collecting and analyzing data to figure out next steps. Right after lunch (vegetable soup and cheese bread), there was a fire drill. There is a drill every week to keep the scientists and crew in practice in case of a real emergency.

Two researchers sit in front of 12 computer screens, reading a display of data. The computer monitors are aboard a research vessel, with a port hole window in the background.
Pat Kelly and Mara Freilich operating the CTD and choosing where to collect water. Credit: Kelly Luis

Afternoon: This afternoon we deployed nine autonomous vehicles from the ship. Autonomous vehicles are ocean robots that sample alongside us to give more information. While outside doing this, we saw a whale and took a moment to watch as it swam near the ship!

A group of researchers, equipped with hard hats and life vests, pull at ropes to assist the S-MODE waveglider lower into the ocean.
Members of the S-MODE mission deploying a waveglider, a type of autonomous ocean vehicle. Credit: Kelly Luis

We also had a Zoom meeting with the whole project team, including the pilots for the autonomous vehicles who work from land, scientists working with instruments on planes that fly over the experiment area every day, and scientists involved in the project in other ways, including numerical modeling. We all discussed our interpretations of what we were seeing and the plan for the next 24 hours.

Evening: After dinner, I helped Sarah calibrate one of the instruments that measures the way that light passes through water, called an AC-S (Spectral Absorption and Attenuation Sensor). This instrument tells us about the biological communities in the water, which absorb and scatter light. (Think about a pond with lots of algae that turns green). While the instruments collect data continuously, we have to maintain them to get good quality data. I took a shower and went to sleep after a productive day. Our cabins are on the deck above the spaces where we work and eat. I share my cabin with Kelly. We have bunk beds. Before going to sleep, I made a plan for tomorrow, but of course it might change depending on how the ocean currents change overnight!

In Dust and Clouds Over Africa, Scientists Find Clues to How Hurricanes Form

By Kathryn Cawdrey, Science writer for NASA’s Earth Science News Team //OVER THE ATLANTIC OCEAN NEAR CABO VERDE//

A layer of dust, which appears brown, layered atop a cloud, as seen from the window of the DC-8 aircraft.
A layer of dust layered atop a cloud, as seen from the window of the DC-8 Airborne Laboratory. Credit: NASA/Kris Bedka

When the dust that wafts off the Sahel and Sahara regions of Africa mixes with tropical clouds, it creates what’s known as a rainy “disturbance” in the eastern Atlantic. These disturbances are hurricanes in their youngest form, and as they travel across the ocean, they can either dissipate or grow into powerful storms.

To study these infant storms, a group of NASA scientists in September 2022 spent a month flying off the northwestern coast of Africa aboard NASA’s DC-8 research plane.  Each day, the team took off from Cabo Verde, an island nation off the west coast of Africa, logging roughly 100 hours altogether. The mission, known as the Convective Processes Experiment – Cabo Verde (CPEX-CV) released its data publicly on April 1.

The CPEX-CV team operated from September 1-30, 2022. Using state-of-the-art remote-sensing lidars, radars, radiometers, and dropsondes—11-inch, lightweight tubes equipped with a parachute that is dropped from the plane to measure wind, temperature, and humidity—scientists captured and logged data for each flight. This month, the instrument teams have submitted data to their respective NASA data archive centers, the NASA Atmospheric Science Data Center and the Global Hydrometeorology Resource Center.

Satellite image of dust over the Atlantic Ocean off the northern coast of Africa. Borders are outlined in black. The dust is mostly between the mainland coast and Cabo Verde.
On September 22, 2022, the CPEX campaign encountered and measured one of the largest dust events that NASA has ever sampled. While the DC-8 Airborne Laboratory captured data with its instruments, the Visible Infrared Imaging Radiometer Suite (VIIRS) affixed to the Suomi NPP spacecraft captured the event from space as pictured above. Credit: NASA

“Combined with the global picture that satellites provide, this data offers finer details that only an airplane outfitted with instrumentation can measure,” said Will McCarty, CPEX program scientist based at NASA Headquarters in Washington, DC.

Photo taken out of a plane window. Part of the engine is seen on the right side. The sky is blue, but the lower part is clouded with puffy clouds and brown dust.
The DC-8 aircraft engines are visible through the passenger window. Each day, the team took off from Cabo Verde, an island nation in the east tropical North Atlantic Ocean, logging roughly 100 hours altogether. Credit: NASA/Amin Nehrir

These observations provide a window into how dust, moisture, clouds, and the ocean interact to either build or prevent intensification of the rainy disturbances that have the potential to become hurricanes. This data, which is open and available to the public, will benefit researchers and weather forecasters, especially those in the atmospheric science community, according to Amin Nehrir, a research scientist based at NASA’s Langley Research Center, in Virginia.

“This can be considered discovery data,” Nehrir said. “It will inevitably help answer questions in years to come that haven’t been asked yet.”

As the plane flew, sensors on the wingtips of the aircraft measured properties of the dust and clouds. Once the plane was above the clouds, onboard remote sensing instruments captured detailed profiles of Saharan dust, wind speed and direction, temperature, moisture, and the structure of convection and rain within clouds. Together these measurements provide an overall, multidimensional view of what’s in the air over the northeast Atlantic, shedding light onto how those variables influence weather systems in their infancy stage.

Photo of NASA's DC-8 airplane flying in the sky near a puffy white cloud.
NASA’s DC-8 Airborne Laboratory—a highly modified McDonnell Douglas DC-8 jetliner—collects data for experiments in support of scientific projects serving the world’s scientific community. The CPEX team outfitted the flying lab with various remote-sensing lidars, radars, radiometers, and dropsondes to study interactions between Saharan dust and tropical clouds. Credit: NASA/Tony Landis

Multiple times in the campaign the DC-8 soared through the Intertropical Convergence Zone (ITCZ), the region where the northeast and southeast trade winds come together. The ITCZ is known by sailors as the calms because of its windless weather. Some of the most remote oceans of the world make up the ITCZ, Nehrir said.

What was most striking to me was being able to look out the window and see how the clouds changed as far as the eye could see from the faint, puffy clouds to cloud streets to convective systems,” he said. You get to see the progression of convective systems all in one shot.

On September 22, 2022, the CPEX campaign encountered and measured one of the largest dust events that NASA has ever sampled.

“We called it the epic dust day,” Nehrir said. “You could see the strength of these atmospheric waves that propagate off the African shore and pick up air and dust.”

These “waves” then interact with clouds and convection to influence the early stages of tropical cyclone genesis, which may or may not turn into a hurricane.

Photo taken out of a plane window. Part of the engine is seen in the lower left corner. The sky is blue, but the lower part is clouded with puffy clouds and brown dust.
The CPEX-CV observations offer a window into how dust, moisture, clouds, and the ocean interact to either build or prevent intensification of the rainy disturbances that have the potential to become hurricanes. This data, which is open and available to the public, will benefit researchers and weather forecasters, especially those in the atmospheric science community. Credit: NASA/Amin Nehrir

The 2022 CPEX-CV campaign was preceded by CPEX in 2017 and CPEXAerosols & Winds in 2021. Data from the previous campaigns is also available to the public.

Nine science projects and 10 instrument and support teams were funded under this campaign, so those investigators helped plan the mission, and now they will take that data back to their home institutions to learn what they can,” McCarty said. “Now it’s off to the races.”

Elation Through Filtration: An Oceanographer’s Sensations at Sea

By Dante Capone, Ph.D. student at the Scripps Institution of Oceanography // ABOARD THE SALLY RIDE //

Being a biological oceanographer on a physical oceanographic voyage has highlighted a key distinction between the two disciplines.

Physical oceanographers rely on sensing – deploying instrumentation that measures properties of the water: temperature, velocity, oxygen, etc. Those data are sent back to laptops allowing for near instantaneous analysis. The day-to-day work of biological oceanography, on the other hand, may be a science best described by filtering – a task that is intertwined with most measurements in our field. We collect water and remove the particles or organisms we want to study. The finest filter might have holes that let only the tiniest particles through, while the largest filter could be something like a large net, where even fish can slip through its mesh.

On the surface, this seems to have drawbacks: the science requires elaborate (but often aesthetic) filtration racks and intensive labor both on the ship and back on shore. It may be months before samples are fully analyzed and in a nicely formatted data table on your computer. However, for me these additional steps have resulted in a greater appreciation for the science and a deeper natural intuition for the water we study.

Different interpretations of the filtration rack aboard the R/V Sally Ride
Different interpretations of the filtration rack aboard the R/V Sally Ride. Credit: Dante Capone

Filtering concentrates the colors and shapes of the particles and plankton in the water, painting them on the canvas of a small, white 25mm lens into the water below us. When passing through a phytoplankton bloom the filter may stain vibrant shades of green, yellow, or red, and with material thick enough to form plankton layer cake. Occasionally, a stray zooplankton – a jellyfish or small crustacean – may unintentionally wind up on your filter, causing the true marine biology nerds to gather around in excitement in an attempt to identify it. We note everything, pack the filters into neatly labeled vials and archive the evolution of our oceanographic journey for analysis back on land.

Tools for filtration and biological oceanographic activities.
Essential tools for filtration and biological oceanographic activities. Upper left) 200uL and 1000uL pipettes and 0.1um filter pack. Upper right) 25mm diameter Supor and glass-fiber filters. Lower left) Filter with phytoplankton and larger gelatinous salp zooplankton. Lower middle) Filters loaded onto rack. Lower right) View of filter with filter funnel from above. Credit: Dante Capone

Part of the reason I enjoy biological oceanography is the variation provided by alternating between typical work on the computer and in the lab punctuated by intense bouts of fieldwork at sea. Compared to the data analysis or paper reading we do back on land, the “sea brain” switches gears, acclimating to more hands-on work. After a handful of experiments, we’ve dialed in our tasks, placing filters, measuring and pipetting water becoming ingrained into our muscle-memory. This frees up the mind and facilitates conversations and a special kind of bonding that can only happen due to the lengthy nature of our sampling.

On the S-MODE campaign, I have been doing a lot of filtering. In my case, I’m interested in measuring grazing in the ocean. Analogous to cattle grazing grass on land, zooplankton graze phytoplankton in the ocean and convert this into energy for larger organisms, or export it to the seafloor as fecal pellets. To make my measurements, I join the party of scientists to gather around the CTD (a suite of sampling instruments) where I collect and filter water into countless labeled bottles to remove any microorganisms. Whether there are waves crashing onto the deck or sun shining on a calm sea, the excitement of science spikes our energy, allowing us to share laughter and meaningful conversation. Back in the ship’s lab we’ll carefully pour our water onto dozens of filters, often powered by lively music.

Scenes from CTD water collection party
Scenes from CTD water collection party. Courtesy of Jessica Caggiano and Jacob Wenegrat.

There may come a day soon when biological oceanography advances to the point of instantaneous measurements. Already, high-tech cameras, acoustics, optics, and even early in-situ DNA measurements pave the way to phase out filtration. However, for now we will continue to enjoy the opportunity to slow down and enjoy letting each parcel of water we collect pass through our hands.

A Nervous Flier’s Guide to Riding the Snowy Skies

By Erica McNamee, Science Writer at NASA’s Goddard Space Flight Center //OVER NEW YORK STATE//

I grew up flying in planes. I’m comfortable in them. But there’s one part of flying I’ve never gotten used to: turbulence. It’s common on commercial flights, so over the years I’ve learned a few tips and tricks on how to stay calm when my mind seems to take off at a sprint.

First, keep an eye on the professionals. On commercial flights, if the flight attendants are up and moving, I relax.

Second, look out the window! It not only helps to see what you’re headed into, but the views? Spectacular.

Finally, breathe deep and ignore the bumps.

But a recent flight, my tried and true tricks didn’t work. This blog comes to you from NASA’s P-3 plane for the Investigation of Microphysics and Precipitation for Atlantic Coast Threatening Snowstorms (IMPACTS) field campaign.

We’re flying through snowstorm clouds… seeking out turbulence … for 8 hours … on purpose. The scientists onboard want to find out how clouds form to ultimately improve the prediction of winter weather.

View out a plane window over the wing. The sky is entirely gray as the plane flies through a storm cloud.
Take a look out the window of the P-3 plane over the left wing as it through a winter weather cloud. Credit: Erica McNamee

The scientists were focused on the data they were gathering, and not often walking around, so it wasn’t as easy to gauge the severity of the turbulence by them. Unfortunately, there were also very few windows, and even looking outside of them didn’t prove helpful, because I could almost always only see into the gray clouds we were flying through. And finally, it was verydifficult to ignore the bumps as we chased down the storm clouds.

“It is important to get measurements of cloud properties directly,” said Greg McFarquhar, director of the Cooperative Institute of Severe and High Impact Weather Research and Operations (CIWRO) and professor at the school of meteorology at the the University of Oklahoma. “The detailed measurements of size distributions, high resolution particle imagery, humidity, total water content, and vertical velocities are not available by any other means.”

The P-3 is an impressive plane, and it has to be for the level of science occurring on board. Instead of rows upon rows of seats, the body of the plane is almost filled with monitors and computers, showing real time data collection from the instruments attached to the underside of the plane – in-situ probes.

“We’re basically looking at every possible aspect of a cloud,” said Christian Nairy.

Nairy and his colleague, Jennifer Moore, are both Microphysical Probe Operators for the University of North Dakota. They were two of the scientists aboard the P-3 during this flight, watching and gathering data from 10 instruments.

Microscope image of a snowflake that appears star-shaped.
tellar-like dendrite (snowflake). These snowflakes grow in the dendritic growth region (DGZ) typically between -12 and -18 degrees Celsius. Image courtesy of Christian Nairy.

These probes measured several forms of precipitation, from detecting icing and supercooled water to looking at the shape of the actual liquid and ice particles.

The P-3 is designed differently than most other commercial aircraft to allow for the data to be collected. It can fly long distances which allows it to transit winter storms to sample multiple parts of the storm as it evolves. It also can fly through supercooled water, which is common between 0°C and -20°C and is important when studying the processes of winter storms.

The plane is also increasingly louder than anything you’d experience on the everyday flight. It’s important for the scientists to keep in communication though, so each person on the flight is hooked up to headsets, constantly switching in and out of talking, frequently asking questions like “what habits are we seeing?” and “what does the cloud look like?” and “what are we seeing on the probes?” The scientists respond to the probed questions with descriptions of the data while the instruments measure in real time.

Four scientists strapped into their seats, focusing on the scientific data on the monitors and laptops in front of them. The photo is taken from behind them. the scientists are sitting in what appears to be the inside of a passenger plane that has been gutted and filled with scientific instruments.
Four scientists strapped into their seats are frequently checking and noting information from the monitors which are linked to the probes attached to the plane. Credit: Erica McNamee

Throughout this flight, I figured out another calming trick knowing what exactly is causing the turbulence is as logical an explanation as you can get. How can I petition for these probes to be on all commercial flights?

“Once you understand what turbulence is, how it’s normal, what is causing it, and how aircraft are built to withstand so much more than it actually takes on, you feel better about it,” Nairy said.

“You just kind of get used to it, and now I find it relatively funny,” Moore said, imitating bobbing up and down on the bumpy flight.

Though turbulence may be an inherently frightening or uncomfortable experience, there are real explanations as to why it is happening. So next time you experience turbulence – or for that matter, next time you experience a snowstorm from the ground – thank the scientists completing research from above.

If not from me, take it from the experts:

“Relax, enjoy the flight, and ask lots of questions,” McFarquhar said.

Photo into the cockpit of a plane, flying over storm clouds around sunset. There are two pilots in the cockpit, each with their own steering devices and monitors and gauges.
The pilots navigate the plane along the flight path as the sun begins to set for the day. Credit: Erica McNamee

The Adventures of NASA Scientists through the Florida Marshes

By Erica McNamee, science writer for NASA’s Goddard Space Flight Center // GREENBELT, MARYLAND //

Look up to the blue skies, look right to the boats floating out at sea, look left to the deep green marshes of the Everglades and Big Cypress National Parks in Florida. This mangrove ecosystem contributes to the larger cycle of greenhouse gases, by both releasing and taking in carbon-containing compounds. How much, you might ask? Let’s find out!

View over the left wing as we flew over mangrove forests in the western portion of the park north of Whitewater Bay. Credit: Pilot Lawrence Grippo

This fall, scientists from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, took to the skies (and sea and land) to take measurements of carbon dioxide and methane as part of the Blueflux field campaign.

Blueflux, funded by the NASA’s Carbon Monitoring System project, aims to create a database of carbon dioxide and methane fluxes – or intakes and emissions – of mangrove ecosystems, which exist in coastal areas.

“The mangroves are of interest for Blueflux because they’re really good at taking up and storing the carbon dioxide,” said Erin Delaria, post-doctoral associate at Goddard.  

The mangroves’ ecosystem plays a role in the movement of climate-changing greenhouse gases: taking in carbon dioxide and emitting methane. Naturally, the Blueflux team was out to measure all that and more.

To make the measurements, Delaria flew aboard a plane, flying around 300 ft (91.44 m) above the marshy environments of the Florida coast below. The scenery was beautiful, she said, flying over the crystal turquoise water and even spotting dolphins from above. In addition to measuring carbon dioxide and methane, the onboard instruments also tracked wind speed and water vapor.

Even before analyzing the data, Delaria said she could see trends in the intakes and emissions of the compounds. In comparison to a previous field campaign taken during the dry season in April of 2022, there were significant increases in methane emissions during the wet season. Classifying the data by the vegetation below the plane, the mangroves had the highest carbon dioxide uptake, while sawgrass marshes indicated less.

The field crews measured gas fluxes in the mangrove ecosystems, towing their equipment as the made their way through ghost forests and regenerating forests. Credit: Jonathan Gewirtzman, Yale

On the ground below the plane, you could find Ben Poulter, research scientist with Goddard’s biospheric sciences lab.

“One of the exciting components of Blueflux is the diversity of partners, which is necessary because we’re taking quite a multidisciplinary approach to how we make the measurements,” Poulter said.

There were different teams working simultaneously, he said, with the plane flying over the scientists on boats, while others hiked through the mangrove swamps. All shared the common mission of measuring the compound fluxes in a bottom-up-top-down approach. Teams from NASA, the National Park Service, and universities all contributed in the campaign to tie together the various forms of measurements around the ecosystem.

“We hope to reduce the uncertainties in the flux estimates and start a discussion about how to balance the fact that these ecosystems are removing carbon dioxide, but at the same time they are releasing some methane,” Poulter said.

The final product of the project is set to be a collection of several maps that will give a timescale history of carbon dioxide and methane fluxes in mangrove ecosystems. The maps will hold valuable information for both scientists and stakeholders that are actively working to restore or protect mangrove ecosystems, for better understanding of their net benefit on the climate.

“Understanding what the natural world is doing when it comes to greenhouse gases is really important to contextualize the human impact on these systems,” Delaria said.

The team has four additional field campaigns scheduled to round out the collected data, with the next trips set to take place in February and April.

View flying out over Florida Bay south of the Everglades and north of the Florida Keys. Credit: Pilot Lawrence Grippo

NASA’s S-MODE Mission: “Sea-ing” through Rainbow-Colored Glasses

By Sarah Lang, Ph.D. student at the Graduate School of Oceanography, University of Rhode Island. // Aboard the Bold Horizon //

If you asked a random person about the color of the ocean, they would probably tell you that it’s some shade of blue or green. But perhaps that shade of blue looks slightly different to you than it does to the random stranger you’re bothering about the color of the ocean.

The way you see color depends on many things: the way an object interacts with incoming light, the color of that incoming light, and even the way your eyes perceive that light. The stranger likely has cone cells in their eyes that perceive light differently than yours.

When light from the sun enters the ocean, it is scattered or absorbed by phytoplankton (microscopic organisms in the ocean that produce oxygen, take up carbon dioxide, and serve as the base of the marine food web), organic matter, minerals, and other constituents in the water, as well as the water itself.

These interactions affect different wavelengths of light differently. Remember the electromagnetic spectrum? Let’s think of colors as different wavelengths of light.

Graphic of visible light portion of the electromagnetic spectrum, with red (longer) on left and white (shorter) at right.
The visible region of the electromagnetic spectrum. Credit: NASA

If we can quantify how light scatters and absorbs after entering the water, we can gain a better understanding of what is in the water. This includes not only how much phytoplankton, but what species there are! This is important for better understanding the ocean’s carbon cycle. Different species of phytoplankton contribute to the ocean’s carbon cycle in different ways (eg., phytoplankton size influences how much carbon they fix), so it is important to understand their distributions.

I am a Ph.D. student at the University of Rhode Island’s Graduate School of Oceanography. I’m interested in how the physics of small-scale features in the ocean affect phytoplankton ecosystems, and I work with ocean color to better understand the biogeochemistry and ecology of the ocean.

Photo of me filtering seawater samples for particulate organic carbon (POC). Courtesy of Kelly Luis.

During the S-MODE campaign, we are using ocean color to capture small-scale variability in phytoplankton species and physiology (how happy are the phytoplankton?).

Here’s how we do it: we take many, MANY seawater samples (we took over 300!) and we analyze these samples for chlorophyll (tells us about how much phytoplankton are in the water), particulate organic carbon, pigments (what types of phytoplankton might be there?), and nutrients.

Mackenzie Blanusa and I tag-lining a CTD-Rosette as it is lowered into the water to collect seawater samples at depth. Photo courtesy of Pat Kelly.
Pat Kelly and I holding our URI-GSO flag in front of the CTD-Rosette. Photo courtesy of Pat Kelly.

We use these samples to “calibrate” ocean color (aka bio-optical) measurements. One way we take these bio-optical measurements is from a flow-through system. We send water through a series of optical instruments that measure different optical properties of the water. Basically, we want to turn continuous optical measurements taken on the ship into biological parameters we understand (like phytoplankton!).

Photos of optical flow-through system. Water flows through the system and is measured by each instrument in succession. The switch will automatically switch between filtered water and total seawater so we have measurements of the dissolved constituents of the seawater and the particulate constituents of the seawater. Beam attenuation describes how much light from a beam is lost when it travels through the water. Backscattering describes how much light is scattered in the backwards direction. All these “optical measurements” are useful in describing the biogeochemistry of the water. For example, beam attenuation can vary with the amount of particulate organic carbon in the ocean. Backscatter can be used as a proxy of particle size. Most instruments are borrowed from Emmanuel Boss’s lab at the University of Maine. Advanced Laser Fluorometer from SIO. IFCB from URI.

Then, we can use these bio-optical measurements to validate measurements from AIRPLANES! These planes (NASA PRISM: Portable Remote Imaging Spectrometer and SIO MASS: Modular Aerial Sensing System) have hyperspectral sensors on them measuring how much light is leaving the water at different wavelengths.

Hyperspectral sensors are really cool because instead of knowing how much light is leaving the water at a few wavelengths across the visible spectrum, we can capture continuous information (almost the whole spectra!). Hyperspectral measurements give us the information we need to estimate phytoplankton species.

Soon, we’ll have global hyperspectral ocean color data for the first time. We’ll be able to see the ocean in a way we’ve never seen before with NASA’s upcoming satellite mission PACE (Phytoplankton, Aerosol, Cloud, and ocean Ecosystem). New discoveries about our amazing planet will follow!

Following the Ocean Fronts

A pink and purple sunrise over the ocean.
Picture of the sky cloud coverage from the Bold Horizon on the morning of October, 17th. Credit: Audrey Delpech.

By Audrey Delpech, postdoc in the Atmospheric and Oceanic Sciences department at UCLA

Being part of the NASA S-MODE oceanographic mission was a great experience for me. It was only my second oceanographic mission and my first one on a US research vessel. I learned a lot about how to use the different instruments, interpret their data and about the complexity of the ocean.

This mission is designed to study submesoscale fronts – which correspond to abrupt changes of water temperature or salinity over scales of about 6 miles or 10 kilometers in the ocean. They act in a similar way as we have fronts in the atmosphere that bring us cold or warm weather, rain or dry air masses. S-MODE is making the first observations that show such fronts do play a role in stabilizing our climate by acting as a connector between the deep ocean and the atmosphere, and controlling the exchanges of quantities such as heat or carbon.

Figure of the sea surface temperature measured along the ship course and the position at which radiosonde were released across a front. Credit: Audrey Delpech.
Figure of the sea surface temperature measured along the ship course and the position at which radiosonde were released across a front.
Credit: Audrey Delpech.

Because these fronts move and change throughout the day, we didn’t have a set sampling plan. Instead, we would look at the real-time conditions so we could figure out where to go and how to get the best measurements from the ship and three aircrafts. This is called “adaptative sampling.”

My research has lately evolved towards understanding how the ocean interacts with the atmosphere above. I have been working with models to simulate and study how submesoscale ocean motions interact and exchange energy with the winds. Onboard the ship I worked with an instrument called a radiosonde. Radiosondes are sensors which are attached to a balloon and  measure temperature, humidity, wind speed and direction as they rise up in the air. I’m interested in seeing how the temperature of the ocean across these fronts influences the wind speed of the air above. We released radiosondes at regular time intervals as the ship was moving across fronts. These measurements will hopefully confirm the findings from the numerical models, and I am really looking forward to analyze them.

A woman stands at the rail of a boat, ocean in the background. Her hands are up as they have just let go of a balloon with a white instrument the size of a cup dangling from it.
Radiosonde launch. Credit: Audrey Delpech.

Another important part of my work onboard was to provide real-time weather conditions from the ship. The onshore team used my reports every day to make the decision of whether to fly the aircraft or not, or if they needed to adapt their survey region. Some airborne instruments required clear-sky conditions or high enough clouds so they could fly in the clear underneath. The radiosondes measurements helped me figure out how high and how thick the clouds were, two important parameters to characterize the cloud coverage.

A graph that shows the altitude on the y-axis and a line showing relative humidity lowering as it goes higher and a second line showing temperature decreasing as it goes higher. A bar indicates the cloud layer from 1 kilometer to 1.5 kilometers above the ocean surface.
Temperature and humidity profile measured by the radiosonde. The saturation (100%) relative humidity layer indicates the cloud layer. Credit: Audrey Delpech

I also collected radiosondes’ atmospheric temperature and humidity profiles from the sea surface to about 8 km height at the same time the airplanes were flying overhead. These data will help calibrate the airborne infrared remote sensors.

Besides the weather reports, I also took part in many other operations. One was helping to deploy an instrument called a CTD (for Conductivity, Temperature and Depth). This instrument measures the temperature and salinity of the sweater as a function of depth as the ship is moving across the ocean. This helped us understand the vertical extension of the front in the subsurface ocean (from 0 to about 200m deep). I also helped filter water samples for future onshore DNA analyses, which will give a sense of the diversity of microscopic phytoplankton across submesoscale fronts, deployed and recovered Lagrangian floats, which are designed to drift with currents, helped navigate the ship to chase fronts, and helped with the real-time processing of data.

Two people stand to either side of a about five-foot tall cylindrical instrument they are prepareing to put in the water.
Audrey Delpech, Dipanjan Chaudhuri and Avery Snyder preparing a Lagrangian float deployment operation. (photo credit: Gwendal Marechal)

This experience has taught me a lot about the challenges of “adaptative sampling” and made me think differently about the value of the data collected. I now know the amount of coordination and labor that are behind them.

It was also a wonderful human experience. The community of people we were forming on this cruise was very diverse, with everyone coming from a different horizon. Several nationalities were represented and each person I met has brightened up my experience at sea. I have made some really good friends and met wonderful scientists I am looking forward to collaborate with in the future.


Life at Sea: Books of the Bold Horizon

By Kelly Luis, NASA Postdoctoral Program Fellow at the Jet Propulsion Laboratory, California Institute of Technology // Aboard the Bold Horizon //

ʻAʻohe o kahi nana o luna o ka pali; iho mai a lalo nei; ʻike ke au nui ke au iki, hea lo a he alo. The top of the cliff isn’t the place to look at us; come down here and learn of the big and little currents, face to face (Pukui, 1983, 24).

I brought Sweat and Salt Water: Selected Works by Dr. Teresia Kieuea Teaiwa onboard the R/V Bold Horizon. The book was the last addition to my bag before heading to the airport. I’m not sure why I threw the book in my bag; but I was even more puzzled when I realized late into the cruise, I read Chapter 5: Lo(o)sing the Edge every time I opened the book. Maybe it was the relevance of Dr. Teaiwa’s inclusion of the ʻōlelo noʻeau (Hawaiian proverb) to S-MODE or maybe the navigation of her professional and personal life resonated with my experience navigating aquatic remote sensing as a kānaka maoli (Native Hawaiian) woman. Still in question as the vessel began its final transit to San Diego, I went on a quest to learn about the books brought aboard.

Kelly Luis reading Sweat and Salt Water in the lab. Credit: Kelly Luis

Tucked between the laptops, bungee cords, and camera bags, I first noticed Sarah Lang’s autographed copy of This is How You Lose the Time War by Amal El-Mohtar & Max Gladstone. Between late night CTD transects and long days of filtering during plane overpasses, Sarah Lang quickly finished up The Seven Husbands of Evelyn Hugo by Taylor Jenkins Reid and just started her second book.

Sarah Lang’s autographed copy of This is How You Lose the Time War. Credit: Kelly Luis

When Andy Jessup returns to his bunk after radiosonde launches and saildrone chasing, he immerses himself in fiction, which he later donates to the ship’s library. Jessica Kozik’s exuberance for the sea carries over into her reading. She is three chapters into Blue Mind: The Surprising Science That Shows How Being Near, In, On, or Under Water Can Make You Happier, Healthier, More Connected, and Better at What You Do by Wallace J. Nichols on her Kindle. Balancing graduate coursework in between ecoCTD shifts, Mackenzie Blanusa can be found in the galley with books for her classes.  Audrey Delpech started L’art de perdre by Alice Zeniter on land and tries to sneak in reading time between radiosondes, ecoCTD watches, and assisting with biological sampling. When Pat Kelly isn’t reading fluorescence samples and macgyvering sensors on the CTD, he’s resting up with classics like Sweet Thursday by John Steinbeck and horror thrillers like Pet Sematary by Stephen King.

Andy Jessup’s donation to the ship’s library. Credit: Kelly Luis.

Not everyone brought a book and/ or knew not to bring a book because of our workload. Our chief scientist is a prime example. Up at every hour he can be, Andrey oversees all science operations, determines boat headings in relation to changing fronts and eddies, and still makes it on deck for all Lagrangian float, waveglider, and seaglider recoveries. He did share that on a previous cruise he brought Gödel, Escher, Bach: an Eternal Golden Braid by Douglas Hofstader, a mathematics book he enjoys reading with the shifting sea state. Ben Hodges did not bring a book because he knew he would be busy leading ecoCTD and waveglider operations, but he wished he brought The Ashley Book of Knots by Clifford Ashley to assist with his night watch knot tying course.

Pat Kelly reading in the library. Credit: Kelly Luis.

From my informal survey, it seemed almost everyone wanted to get more into their books, but were worn-out after watches. From keeping up with operations and learning new instruments, we were naturally tired and the comforts of an easy to get lost in piece of work beat out starting something new. My reading of the same chapter may have simply been a deep desire for familiarity. However, I think it may also relate to our chief scientists’ sentiment toward his mathematics book. The shifting sea state provided new glimpses of the relations between the text and my journey, but also the biological and physical relations we observed on the R/V Bold Horizon. Much more can be said about the edges of existing models’ ability to capture sub-mesoscale processes and the importance of meeting these features face to face. However, this chapter of S-MODE 2022 cruise is coming to end, but another chapter awaits the science party in 2023.

Until we meet the big and little currents again.


Mary Kawena Pukui; illustrated by Dietrich Varez. ʻŌlelo Noʻeau: Hawaiian Proverbs & Poetical Sayings. Honolulu, Hawaiʻi: Bishop Museum Press, 1983.

List of Books/Magazines Aboard the Bold Horizon

  • Sweat and Salt Water: Selected Works by Teresia Kieuea Teaiwa
  • Science on a Mission: How Military Funding Shaped What We Know and Don’t Know About the Ocean by Naomi Oreskes
  • Pet Semetary by Stephen King
  • Sweet Thursday by John Steinbeck
  • Three body problem by Liu Cixin
  • L’art de perdre by Alice Zeniter
  • Mermoz by Joseph Kessel
  • Le serpent majuscule by Pierre Lemaitre
  • This is How You Lose the Time War by Amal El-Mohtar & Max Gladstone
  • The Seven Husbands of Evelyn Hugo by Taylor Jenkins Reid
  • Hunter-Gathers Guide to the 21st Century: Evolution and Challenges of Modern Life by Heather Heying and Brett Weinstein
  • The Sentence by Louise Elhrich
  • Blue Mind: The Surprising Science That Shows How Being Near, In, On, or Under Water Can Make You Happier, Healthier, More Connected, and Better at What You Do by Wallace J. Nichols
  • Birds of Southern California: Status and Distribution by Jon L. Dunn and Kimball Garrett
  • The Book: On the Taboo of Knowing Who You Are by Alan Watts
  • The Outermost House by Henry Beston
  • The Flame Throwers by Rachel Kushner
  • Shame of a Nation: The Restoration of Apartheid Schooling in America by Jonathan Kozol
  • Why are all the black kids sitting together in the cafeteria? And Other Conversations About Race by Beverly D. Tatum
  • Essentials of Atmosphere and Ocean Dynamics by Geoffrey K. Vallis
  • Le voyage d’Emma
  • Hermann Hesse by Siddhartha
  • The Orion Magazine
  • High Country News

Surface Waves from the Bold Horizon’s Deck During NASA’s S-MODE Experiments

By Gwendal Marechal, postdoctoral researcher at the Colorado School of Mines // Aboard the Bold Horizon //

Upon leaving the Breton coastlines after my Ph.D., I started a postdoc at the Colorado School of Mines. After one month in the Colorado mountains, I traveled to Newport, Oregon, to board the Bold Horizon for one month of measurements offshore of San-Francisco for the NASA S-MODE (Sub-Mesoscale Ocean Dynamics Experiment) field campaign. This experiment focuses on sub-mesoscale currents (spatial scales smaller than about 30 km, or 18 miles, at these latitudes), and tries to assess how important these structures are for the vertical exchange in the ocean and fluxes between the lower atmosphere and the upper ocean.

We set sail for the experiment area after six days of mobilization in Newport. This is my first cruise that focuses on a different topic than surface gravity waves (waves hereafter). Actually, during this cruise, the (steep) waves were mostly a drawback for the CTD, Eco-CTD casts, and floating/underwater platform (sea-gliders, wave gliders, Saildrones) deployments. These waves were, however, one of the main focuses of the Twin Otter airplane flying above us during the S-MODE experiment. This aircraft and its instrument MASS were flying almost every day throughout the cruise collecting the sea-state properties at very high resolution. In other words, it measured the wave height, direction and wavelength. Also, with its optical sensor, MASS is able to capture the breakers resulting from waves, the famous “sheep” at the ocean surface.

The Twin-Otter aircraft during the S- MODE campaign. Credit: Alex Kinsella

Even if we are not measuring waves directly from the Bold Horizon, some of our floating platforms, such as the Saildrones and the wave gliders, do measure waves. Because the waves play the role of a liquid boundary between the ocean and the atmosphere, they strongly interact with the two systems. Therefore, in the context of measuring the sub-mesoscale currents and their associated air-sea fluxes and mixing in the upper ocean, measuring waves is mandatory.

For instance, currents can enhance the breaking probability of the waves and thus the associated air-sea fluxes. One can notice the effect of the current on waves at front locations captured from the Twin-Otter aircraft.

Waves across current front from Twin-Otter aircraft. One can see more whitecaps on the left side of the front. Credit: Nick Statom.

During the cruise we have experienced a large number of sea states, from calm ripples to almost 4 meter (13 feet) wave height during one night (October 23rd). The wave height is not actually a drawback for instruments deployments and the life onboard; indeed, waves can be high, yet very long, allowing the ship to travel on them like on smooth hills. On the other hand, the steep waves, those that are short and high, definitely cause a strong pitch and roll of the ship and therefore an uncomfortable sleep or the end of CTD casts. However, those waves were always welcomed with joy by the night watch (from 4 p.m. to 4 a.m.). Seeing the dry lab, the dining room, and the bridge tilting by more than 10 degrees has nothing to envy from a traditional roller coaster. Make sure that your belongings are firmly attached!

A collection of photos of the ocean and the sky, showing varying heights of the waves.
Caption: Daily pictures of the sea-state from October 9th to the 29th from the Bold Horizon Credit: Gwendal Marechal

I spent most of my free time observing waves from the deck or the bridge of the ship. Well, my free time during daylight was no longer than 2 hours daily, and this was my chance to discuss with the whole scientific team, because this was the only time when everyone was awake. I took the opportunity to be with expert in air-sea interactions to learn about the atmospheric boundary layer from simple cloud observations or radiosonde deployments. Certainly, I have learned a lot about cloud formation, cloud dynamics, and how the clouds are strongly linked to the sea surface temperature. On my side, I tried to share my “nerdy” wave-knowledge about wave breaking, sea-spray emissions, wave modulation, and what I understand in general about this moving superficial layer of the ocean.

Measuring waves or not, this cruise was definitely a new crazy adventure at sea with the night watch team (Mackenzie, Jessica, Igor, Ben, and Alex) and the crew in general. I’m looking forward to the next cruise for a new journey!

Wave steepness and Significant Wave Height from the Point Reyes buoy offshore San-Francisco. The steepness has been computed from the mean wave period (T) and the significant wave height

Cloudy with a Chance for Whirlpools: Ocean Models Guide NASA’s S-MODE Mission

By Joseph D’Addezio, oceanographer with the U.S. Naval Research Laboratory // NASA’s Stennis Space Center in southern Mississippi //

NASA’s S-MODE mission faces quite the challenge: robustly observe, for the first time, ocean features spanning up to about 6.2 miles (10 kilometers) across. Currently, the oceanographic community routinely observes and studies very large ocean features, primarily through space-based instrumentation. These include strong currents such as the Gulf Stream that runs from Florida along the East Coast of the United States all the way to western Europe. Large vortexes are also observed – these being the cyclones and anticyclones you may have seen on your evening weather forecasts.

(Top) A photo of Joseph. (Bottom) GIF of ocean currents and whirlpools off the coast of San Francisco, California. Credit: Courtesy of Joseph D’Addezio

On the other end of the size spectrum, we also understand quite a bit about much smaller ocean features such as surface waves you’ve seen every time you visit the beach. The features S-MODE is targeting are unique specifically because they are too small to be seen from space and too large and sparse to be sampled without having to commission a ship and an array of many other instruments.

So, S-MODE is on the hunt for these elusive features. Ocean models are one of the tools that S-MODE is utilizing. You may be aware that meteorologists are often aided by predictions provided by weather models. Fortunately for oceanographers, the same mathematical equations used by weather models can be used to predict the ocean. The Navy runs daily ocean models to estimate the current state of the global ocean and predict what the ocean may look like in several days. This ocean prediction capability is where the Navy and S-MODE intersect: ocean models provide another tool S-MODE can use to make targeted observations in its quest to find and understand kilometer-scale ocean features.

Running an ocean model is not easy. Firstly, the mathematical equations must be solved on a large three-dimensional grid using supercomputers. This requires many times more computation than what is available to the smart phone you may be reading this on. Secondly, the equations are extremely sensitive to the accuracy of the initial ocean state. Small errors in the initial estimate of the ocean increase exponentially with time. This problem is combated by routinely incorporating recent observations into the model to correct the errors the model is accumulating with time. This process is called data assimilation (yes, like the Borg aliens in Star Trek). This process is mostly science with a touch of art. I mean that decades of research have been poured into the subtleties of how to optimally blend the model prediction and the incomplete, but invaluable, observations we have of the ocean.

Ultimately, the ocean model is a useful but imperfect tool for the S-MODE mission. The model can’t tell S-MODE exactly where the kilometer-scale features of interest are, but it can give hints. A useful analogy might be tornado chasers. Operational weather models do not accurately predict exactly where a tornado will spawn. They do however tell astute users where favorable conditions exist for a tornado to form. The tornado chasers can then travel to an area of interest based on the model and use tools like radar (and at some point their eyeballs) to track a tornado. S-MODE employs a similar methodology. The ocean model will update using recent

observations and make a new prediction every day. The S-MODE team can monitor how the model expects the larger scale features of the region to evolve and move their ship to a region where features of interest might be expected to form. 

About Joseph D’Addezio:

I work on research and development for the Navy’s ocean models, with a specific focus on data assimilation: the process by which the ocean model is updated to include information from recently taken observations. My group and I are stationed at NASA’s Stennis Space Center in southern Mississippi. Stennis is known primarily as a test site for NASA rocket engines. Sometimes the walls of the office shake. Most importantly, nothing beats New Orleans food. We could do without the hurricanes though.