you're reading...

Book Review

Small scale, big effect

Su, Zhan, et al. “Ocean submesoscales as a key component of the global heat budget.” Nature Communications 9.1 (2018): 775. doi:10.1038/s41467-018-02983-w

We hear a lot about resolution in our increasingly digital lives. Most consumers worry about it in terms of imaging ­– think 4K Ultra High Definition televisions or 12-megapixel camera sensors in iPhones. But the concept of resolution applies in all digital domains, including the climate models scientists use to make predictions about our planet.

For decades, climate scientists have used computational models to study the Earth system as a whole. They create digital approximations of the world by dividing it into a 3-dimensional grid and writing mathematical rules that govern the physical relationship between the parameters they are studying. When climate modelers discuss resolution, they are referring to the size of the boxes in the grid.

Most global climate models have resolutions of 10s of kilometers, setting a lower limit to what types of physical phenomena can be described. This is akin to taking a picture with a low-resolution camera – you might be able to see a person’s face, but cannot quite make out their eye color. In their new paper, Dr. Zhan Su and his colleagues at CalTech and the Jet Propulsion Laboratory argue that climate models have been missing the effects of submesoscale processes due to limited resolution.

Figure 1 – A satellite image of submesoscale structures in the Baltic Sea. Notice how the feature swirl together and the 20 km scale bar (Adapted from Su et al., 2018).

The term submesoscale describes physical features in the ocean that occur at spatial scales of 10s of meters to several kilometers. Scientist often describe eddies as submesoscale phenomena (fig. 1). These structures are often observable from satellites and vessels. Recent work by other groups has suggested that they account for about half of the variability in vertical velocity in the ocean. The implication is that relatively small, local features play an outsize role in how water moves between the ocean’s surface and interior.

The water circulated between the surface and inner ocean governs the magnitude and direction of air-sea heat exchange. The heat flux between the ocean and the atmosphere is a critical component of the Earth’s climate system. In fact, scientists estimate that the ocean has taken up a substantial amount of the heat associated with anthropogenic climate change. Su recognized that incorporating the effects of submesoscale features might dramatically change the output of climate models. The point is not purely academic – climate models are used to inform policy decisions on the international stage.

Figure 2 – Output from the high resolution model corresponding to March, 2012. The insets are details from the Northern and Southern hemispheres (adapted from Su et al., 2018).

Su and his team leveraged powerful computers at the NASA Advanced Supercomputing facility to run a global model with about 2 km resolution. Each cell in the model represented 1/48 of a degree of latitude. The researchers forced the model with atmospheric and tidal information. The team then had it output predictions for a 14-month period corresponding to September of 2011 to November of 2012 (fig. 2). A separate, coarser model was run with the same inputs for comparison.

Su’s high-resolution model demonstrated that submesoscale features enhanced the amount of vertical heat transport across the entire global ocean. The mixing caused by the small-scale features generally resulted in a warmer surface and cooler inner ocean. The effect was more substantial in the winter when storm activity caused the ocean to be more energetic. At most grid points, the higher resolution model exhibited greater upward heat flux than the coarser simulation.

The group argues that their results demonstrate that submesoscale dynamics exert an important influence on the global the ocean. The effect of these relatively small processes could also have an impact on atmospheric dynamics. Su points out that the only way to assess the interplay is to develop models that more tightly couple the ocean and atmosphere at these resolutions.

Fleshing out the details of the interaction between small processes in the ocean and the climate is critically important. If the submesoscale is as influential as Su and others suggest, then the models used to predict the future of our planet might be in need of a big adjustment.


No comments yet.

Post a Comment


  • by oceanbites 2 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 3 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 4 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 5 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 5 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 7 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 8 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 8 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 9 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 9 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 10 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 11 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 11 months ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com