How are Phytoplankton Involved in Cloud Formation?

This is Jim Fiorendino, your host for On the Ocean

Earth’s ocean and atmosphere form a complex interconnected system. With over 71% of Earth’s surface covered by water, the dynamics of the world’s oceans can have considerable impacts on atmospheric processes such as cloud formation. Studying cloud formation is important because clouds influence Earth’s heat budget and, consequently, Earth’s climate and weather. Clouds form when water condenses or ice crystals grow on aerosol particles in the atmosphere. The breaking of waves on the ocean entrains bubbles in the water, which rise and burst. Bubbles bursting and waves breaking launch water droplets containing organic material into the atmosphere, which dry out and form cloud condensation nuclei or ice nucleating particles. A diagram of this process is shown in Figure 1 below.

Dr. Daniel Thornton of the Texas A&M University Department of Oceanography is currently working with a team of scientists to understand the role of oceanic processes in cloud formation. Specifically, Dr. Thornton is studying the production of organic material in the oceans by phytoplankton.

Phytoplankton are microscopic photosynthetic organisms that form the base of oceanic food webs. They are known to form compounds that promote cloud formation, such as exopolymers. Exopolymers are large, irregularly-shaped molecules comprising roughly 10% of the organic matter in the ocean. This material leaks out of cells, particularly when they are eaten or die (Figure 2). Once in the ocean, this material may be carried to the surface by bubbles, where it is concentrated in a thin layer known as the sea surface microlayer. Wave activity can transfer this material to the atmosphere. Dr. Thornton hopes to link the biology of marine phytoplankton to the composition of organic matter in the ocean and the properties of marine organic aerosols in the atmosphere.

This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.

Thornton_Aerosols_Diagram

Figure 1. Ecosystem processes affecting the formation of marine aerosol (a) Phytoplankton fix inorganic carbon into organic matter. Phytoplankton productivity is affected by environmental factors such as the availability of energy (sunlight) and nutrients. A web of interactions (green arrows) between organisms affects the formation and transformation of organic matter. Heavy green arrows emphasize processes that produce large amounts dissolved organic matter (DOM) and particulate organic matter (POM). The metagenome represents the genetic potential of the community, including metabolic pathways that affect the fate of organic matter. Labile organic matter is utilized by heterotrophic bacteria, most of which is ultimately remineralized back to inorganic carbon (CO2). A small proportion of the organic matter fixed by photosynthesis may join the large pool of refractory organic matter in the ocean. Organic matter from the ecosystem fluxes to the atmosphere as volatile organic carbon (VOC) compounds and organic-rich primary marine aerosol (red arrows). (b) Volatile organic compounds (such as dimthyl sulfide (DMS)) flux from ocean to atmosphere, where they undergo oxidation reactions leading to the formation of secondary organic aerosol that may act as cloud condensation nuclei. Breaking waves entrain bubbles that scavenge organic matter from the water and burst through the sea surface microlayer (SML), throwing organic-rich primary aerosol into the atmosphere. A proportion of the primary aerosol may act as cloud condensation nuclei (CCN) or ice nucleating particles (INP).                                                                                                                                                                                                                                                                                                                                Brooks SD & Thornton DCO (accepted) Marine aerosols and clouds. Annual Reviews of Marine Science

Thornton_LeakyCells

Figure 2: Cell permeability in the diatom Thalassiosira weissflogii (CCMP 1051) visualized by epifluorescence microscopy. Cells were stained with SYTOX Green (Invitrogen, Life Technologies, Grand Island, U.S.A.), a membrane-imperme- able nucleic acid stain. Chlorophyll autofluorescence is shown in red and SYTOX Green stained nucleic acids are shown in green. A. Intact cell containing chlorophyll but no SYTOX Green staining and therefore intact cell membranes. B. Intact cell containing chlorophyll with compromised cell membranes revealed by the staining of an intact nucleus with SYTOX Green. C. Dying cell with low chlorophyll autofluorescence, a disrupted nucleus and compromised cell membranes. Image courtesy of Jie Chen. Scale bar = 10 μm.                          Thornton (2014) European Journal of Phycology 49: 20-46

Contributing Professor – Dr. Daniel Thornton

The Role of Ocean Biology in Cloud Formation

This is Jim Fiorendino, your host for On the Ocean.

Clouds are composed of water and ice that has adhered to suspended particles in the atmosphere. These particles, and the clouds they help form, are capable of scattering or blocking incoming radiation from the sun and absorbing and emitting heat energy. Studying the processes that control the formation of clouds is therefore essential to our understanding of Earth’s heat budget, weather, and climate.

Cloud formation is a complex process that requires the presence of fine particles suspended in the atmosphere, known as aerosols, which serve as a surface to which water can adhere or freeze. Ice clouds appear wispy, and form high in the atmosphere, while clouds composed of water particles are fluffier and form lower in the atmosphere. Particles conducive to cloud formation are known as either cloud condensation nuclei or ice nucleation particles; the ability of these particles to promote cloud formation depends upon particle size and chemical composition. Pure water in the atmosphere will not form clouds.

The ocean and atmosphere are closely linked; understanding atmospheric processes such as cloud formation requires studying related processes occurring in the ocean. Roughly 71% of Earth’s surface is covered by water, providing a large area over which the ocean and atmosphere interact. At the interface of the atmosphere and ocean, heat, gasses, and other material are exchanged.

Waves break across the entire surface of the ocean; when waves break, droplets of water are thrown into the air. In addition to salt water, these droplets may contain microorganisms, as well as solid and dissolved organic matter. If the particles are small and light enough, they may be carried high into the atmosphere where they become cloud condensation nuclei or ice nucleating particles. Scientists in Texas A&M University’s Department of Oceanography and Department of Atmospheric Sciences are currently working to understand what role oceanic processes, particularly ocean microbiology, play in cloud formation.

This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.

 

Contributing Professor – Dr. Daniel Thornton

Gliders -4 Glider Data

Gliders -4 Glider Data

I’m McKensie Daugherty, your host for On the Ocean. Gliders are instrument systems capable of covering incredible distances of ocean, taking measurements throughout. But what kind of things do they measure? Scientists have many questions about the composition of the ocean, and how that relates to oceanic and biological phenomena. As such, the gliders are formatted with a suite of instruments to take different kinds of measurements for the scientists needs. These measurements include data about temperature, salinity, dissolved oxygen concentration, chlorophyll, and dissolved organic carbon. The gliders can also be outfitted to gather data about nutrients (like nitrate), hydrocarbons (like oil and gas products), carbon dioxide, and sound. This information helps scientists make connections between what the ocean is made up of, how it reacts to change, and conclude whether it was caused by human impacts or natural variability. With this information, they can begin to assess ways in which to reduce this pollution. Deploying gliders each year can create a time series of this data, so researchers can monitor improvements recognize recovery systems that work best. Scientists at Texas A&M University use this data to understand oceanic phenomena such as hurricane intensification, oil spill movement, harmful algal blooms, hypoxia (which is little to no oxygen in the water), and other processes that can affect people’s lives. By studying these events, and the correlated factors that are unique to them, oceanographers can begin to use this information to make predictions and conclusions to help coastal and oceanic efforts. Overall Gliders provide incredible, multivariate data that can help answer many questions researchers have about the ocean. If you encounter a glider, remember not to approach it, it’s on a very important mission. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.

 

More Information and Links:

Contributing Professor Dr. Steve DiMarco:

http://ocean.tamu.edu/people/faculty/dimarcosteve.html

Page for Gliders that gather Hypoxia data:

https://www.facebook.com/TamuGergGliders

Gliders -3 Open Ocean Gliders

Gliders -3 Open ocean Gliders

I’m McKensie Daugherty, your host for On the Ocean. As we’ve discussed in previous weeks, gliders are incredible powerful instrument systems that allow oceanographers to probe the ocean remotely for long periods of time and covering long distances. But sometimes, as with many scientific instruments, there are some problems scientists have to solve. Gliders move across the open ocean, meaning they are subject to a harsh environment, one with many potential dangers to their mission. Gliders use passive motion, meaning they do not usually use any motorized power to move through the ocean. So, when the direction the ocean is flowing changes, the glider has to move along with it, and large changes can potentially throw it far off course. In fact, this can lead to a glider washing ashore in incorrect places. In an effort to keep this from happening, gliders can be formatted with a propeller that uses battery power to help escape from a strong current. Since the battery life determines the length of the mission, using the propeller is a last resort option. Correct ballasting of the glider is critically important to its ability to function. Ballast measurements before deployment are set to the salinity that is expected at the mission sites. However, if that salinity somehow changes, perhaps due to freshwater runoff from a river, the glider may have difficulty coming to the surface. Another problem scientists had to get creative to solve is the animals living in the open ocean. Remoras are fishes that follow large cruising animals in the ocean by attaching to them. When they sucker on to gliders they affect the weight of glider, making them heavy and unable to move correctly. A nylon mesh stocking was created to fit over the glider, discouraging remoras from attaching. Although there are many potential problems from working in the open ocean, the scientists responsible for those instruments do their best to accommodate and get the most accurate and relevant data possible. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click On the Ocean.

 

More Information and Links:

Contributing Professor Dr. Steve DiMarco:

http://ocean.tamu.edu/people/faculty/dimarcosteve.html

Page for Gliders that gather Hypoxia data:

https://www.facebook.com/TamuGergGliders