Introducing Lagrangian assets deployed during the I07N cruise

Authored by: Emily Smith

As the Ronald H. Brown continues to make its way around the world, it is also deploying many platforms that are used to observe the ocean. These platforms measure temperature, salinity, and ocean currents. Before we had these platforms, all of that information would only be collected by ships. This limited our ability to understand most of the ocean. Now we have instruments all around the world. Some of the instruments that are being deployed by NOAA’s Ship, the Ronald H. Brown are Argo floats and Drifters.   

An Argo float is a free-drifting instrument that moves up and down in the water column. It collects information from the sea surface to 2,000 meters below the surface every 10 days. Each time a float surfaces, it sends measurements of temperature, salinity, with the depth of those measurements to satellites.  

The other free floating platform that is being deployed is a global drifter. A drifter consists of a surface buoy attached by a long drogue (looks like a sock with holes in it). It gathers temperature and ocean current information that it can send to satellites. Drifter data helps us study surface circulation.

Scientists are very excited to be able to put more instruments in the water in the Indian Ocean. This is the first time in many years that measurements are being taken in this part of the world.

I07N 101: Intro to Oceanography

Author: Holly Westbrook

Hello! My name is Holly and I am a scientist. When you read the word “scientist” you might imagine a person in a white lab coat, goggles, and gloves, swirling a flask of strange colored liquid, or maybe frowning at a clipboard. Now, sometimes science does look like that, but other times it looks like this:

ARGO_Deployment
From left to right, Ian, Andy, and Christian deploying an ARGO float.

The scientists onboard the Ronald H. Brown are “oceanographers,” scientists who study the ocean. It can be a tricky field to study because we have to collect samples from places that can’t be easily reached (for example, the middle of the Indian Ocean).

We collect water samples from the bottom of the ocean all the way up to the top using a piece of equipment called a “rosette.” The rosette has many different things attached to it, to bring up water we use “Niskin bottles” (the gray bottles in the next picture). Once the rosette is on deck and secured we can start sampling. There are many different people who need to get water samples. We have a specific order of who goes when to make sure things stay organized and all the time-sensitive samples are collected quickly. Still, things can get a little crowded.

Close_Quarters
From left to right, Chuck, Leah, CFCs Chuck, and Ian working in close quarters to get their water samples.

There are a couple of different ways to collect water, many of us use plastic tubes and glass bottles, some use plastic bottles, some use glass syringes, and one person has a bit more of an involved method:

Christian
Christian sampling black carbon, looks like a pretty involved process.

A lot of the scientists work 12 hour shifts, we usually have another person who will take over our shift when we are done. That means that no matter the time of day there is always research being done! My shift is from 11:30 pm to 11:30 am. It was a little rough adjusting at first, but by now I’ve gotten used to it. Plus I’ve seen some pretty great sunrises.

Sunset
A beautiful sunrise I got to see while waiting for my turn at the rosette.

When we’re not working, how we use our time is up to us. We can read outside, watch movies in the lounge, play card games, go to the gym, or talk to friends online—there’s a surprising number of ways to occupy your time!

Breakfast, lunch, and dinner are prepared by the stewards and they are at the same time every day. But there is always something to eat, which is good because I sleep through dinner and wake up several hours before breakfast. There’s things like oatmeal and cereal, but also daily snacks and ice cream at any time.

The days can be repetitive and tend to blend together but the importance of the work and the company we keep makes it all worthwhile!

Water_Taxi
From left to right: Bonnie, Myself Amanda, Catherine, Carmen, Annelise, and Jenna on a water taxi to Mahé.

Using Sound to Visualize Currents

Author: Amanda Fay

Time is flying! After so many weeks at sea I’m happy to report that spirits are high and everyone is going with the flow. Speaking of flow…let’s learn about currents!

So I am here as the sole person in charge of the LADCP or Lowered Acoustic Doppler Current Profiler, although I get lots of help from Jay and Andy. These instruments are attached to the rosette frame and use the Doppler effect of sound waves to measure the speed of water throughout the water column. ADCPs are very common in oceanographic work and can also be used in an anchored setup on the seafloor as well as mounted on seawalls or bridge pilings. Ships also frequently have ADCPs attached to their hulls, which allows them to take constant current measurements as the boat moves.

In our case, we use LADCPs, which means the instruments are lowered to the ocean floor and then brought back up in order to get a complete profile of the water column. There are 2 LADCP instruments on the platform- one that looks downward (the master) and one that points upward (the slave) as well as a battery pack that provides the instruments with power during their nearly 4 hour ocean voyage (depending on depth of the cast) at each sampling station. When the instruments are on deck between stations, they and the battery are connected to the ship’s power through a train of long black cables.

So what do I do? About 15 minutes before we reach the sampling station, I go into the lab adjacent to the sampling bay and begin the process of getting these instruments up and running in preparation for their next dive into the water. I check their status, erase their current files to make room for new data, and then get them all set to go. They start “ping-ing” and a few minutes later they are in the water.

The ADCP measures water currents with sound using the principles of the Doppler effect. Sound waves have a higher frequency when they move toward you than when they move away from you. The ADCP works by transmitting “pings” at a constant frequency while in the water. As the sound waves travel, they ricochet off particles in the water such as silt or plankton. The reflected sound is then bounced back to the instrument. The waves reflected off of a particle moving away from the instrument send back a slightly lowered frequency, while reflections off particles moving toward the instrument send back slightly higher frequency waves. The difference between what gets sent out and what the instrument receives is called the Doppler shift. The instrument uses this shift to calculate how fast the particle and the water around it are moving.

When the instruments get back on deck I reconnect power to them and the battery and begin downloading the precious data they hold. Some immediate QC is done to ensure things look good (cables haven’t gone bad, the battery is providing sufficient power, etc). Later, I process the data to see what kinds of currents we are seeing in the water. Sometimes this shows that I need to swap out an instrument (no small feat as they are quite heavy and awkward). Currently we have a Master that is operating with only 3 of its 4 beams operational. This is ok- redundancy is key in these types of instruments and they are able to work with just 3 beams, but no less.

And that’s how we use sound to measure the motion of the ocean.

 

International Collaboration at Sea – Being a Japanese scientist on a US vessel

Author: Shinichiro Umeda

The ocean absorbs considerable heat and anthropogenic carbon dioxide (mostly from burning fossil fuels), slowing down the global warming. It is important for the future climate to monitor heat and carbon in the ocean regularly. Although satellite observations and autonomous instruments such as Argo floats are widely used, ship-based hydrography remains the only method for highly accurate measurements of temperature, salinity, and other chemical and biogeochemical parameters over the full water column. The ocean covers about 70% of the Earth surface and international collaboration is inevitable. The international program we are sailing for is called GO-SHIP (Global Ocean Ship-based Hydrographic Investigations Program).

Both JAMSTEC (Japan Agency for Marine-Earth Science and Technology), for which I work, and NOAA are part of GO-SHIP. R/V Ron Brown of NOAA is now observing the I07N section north of 30S. R/V Mirai (Japanese word “future”, see Image 2) of JAMSTEC will occupy the I07S section from 30S to 65S (or ice edge) in the 2019/20 season. The two sections will form a complete trans-basin section, contributing to understanding of the basin scale heat/material circulation of the Indian Ocean.

R/V Mirai has been to the Arctic, Pacific, and Indian Oceans (both subarctic and subtropical) since 1997. Her length is 128.5 m, beam is 19.0 m, depth is 10.5 m, draft is 6.9 m and gross tonnage is 8,706 tons. For hydrographic cruises, she carries 46 scientists on board, deploying CTD, collecting and analyzing water samples, all day and night.

JAMSTEC and NOAA have a long history of collaboration. To better understand and predict climate variations related to El Niño and the Southern Oscillation (ENSO), the TAO/TRITON moored buoy array is operated in the Tropical Pacific Ocean. TAO/TRITON was built over the 10-year period from 1985 to 1994 and is presently supported by JAMSTEC and NOAA.

And another episode of collaboration occurred in 2017. NOAA’s Pacific Marine Environmental Laboratory (PMEL) operates a research mooring at the Kuroshio Extension Observatory (KEO) which is located off the coast of Japan. The KEO surface mooring provides publicly available data including meteorological components such as wind velocity/direction and oceanographic components such as temperature/salinity and surface ocean acidification for international climate researchers worldwide. On October 19, 2017, it broke from its anchor and went adrift. A rescue took place on the high-seas at the end of December 2017, as technicians from JAMSTEC helped recover and redeploy the KEO mooring (See Image 3). The mooring continues to provide important data for the North Pacific research.

There are differences between JAMSTEC and NOAA, such as language, culture onboard, size of scientists onboard, duty team, etc. On the other hand, we (and probably all other sea-going research institutions) all love the sea and science we do, and willing to help each other in need. The collaboration continues.

 

 

 

CFCs: Unintentional Ocean Tracers

Author: Katey Williams

Hi! My name is Katey Williams and I’m working as a CFC analyst with Bonnie Chang and Chuck Kleinwort in the CFC lab aboard the Ronald H. Brown.

 

What are CFC’s ?

CFC stands for Chlorofluorocarbons. As the name suggests, these are chemicals that contain chlorine, fluorine, and carbon atoms. CFCs exist as a gas in both the atmosphere and dissolved in the ocean. These chemicals don’t occur naturally though. They were first manufactured in the 1930s as a non-toxic refrigerant. Older refrigerators used to use toxic gases as refrigerants. However, after a series of fatal accidents due to refrigerators leaking toxic chemicals, the need for a non-toxic refrigerant was recognized. So CFCs were invented. They worked well and were massively produced in the 1960s in refrigerators, automobiles, air conditioner and aerosols.

Unfortunately, the seemingly perfect chemical came with a catch.  Even though CFCs are non-toxic humans, they can cause some serious damage when they enter the upper atmosphere. The upper atmosphere contains the ozone layer, which protects earth by absorbing harmful ultraviolet radiation from the sun. Exposure to ultraviolet radiation can cause mutation in plants, animals, and humans, and can lead to higher rates of cancer and immune system problems. Once it was discovered that CFCs were creating holes in the ozone layer, governments started to ban the production and usage of CFCs. Since 1996, industries have phased out CFCs and the amount of CFCs in the atmosphere has started to decline.

 

What do CFCs measure in the ocean’s water column and why these measurements important?

CFCs may not have made great refrigerant chemicals, but what they do make is great ocean tracers. Even though CFCs have been phased out of industry, they still exist as a gas in the atmosphere. When the gases of the atmosphere interact with the surface of the ocean, some of the CFCs dissolve into the ocean and stay there. As these water masses travel around the ocean and throughout the water column, they take the CFCs with them. CFCs act like a dye in ocean currents that scientist can measure and track. Determining the age and the amount of CFCs in the water column can tell us about the rates and pathways ocean circulation and mixing patterns.

 

How are CFC measured?

Extracting CFCs out of the water column starts with taking water samples from the CTD. We use giant glass syringes to extract water out from the CTD bottles. Since there’s a higher concentration of CFCs in the air in comparison to the ocean, the water sample within the syringe has to be free of air bubbles. Otherwise the amount of CFCs in the water sample won’t be accurate.

After we take our water samples with the syringes, we take them to the CFC lab on the ship to analyze. The CFC lab has a system set up that extracts the CFCs out of the water sample and then runs the gases through a gas chromatogram. The gas chromatogram measures the concentration of CFCs in each of the water samples.

CFC_Lab
System in the CFC lab used to extract and analyze CFCs from the water samples. Gas chromatograms are the last three machines on the right.

 

We’re two weeks into the cruise and have already analyzed over 500 water samples! There will be many more to come as we continue to travel throughout the Indian Ocean, measuring CFCs and tracing ocean currents one sample at a time.