September 2025 | Oceanography
“since its publication, the JHTDB had become a gold standard and
an hypothesis testing tool in the turbulence community” (Shnapp
et al., 2023). This opening up of cutting-edge benchmark simula-
tions has been termed “democratizing the data.” In addition, such
databases significantly reduce carbon emissions by reusing extant
data rather than recomputing them (Yang et al., 2024).
Inspired by the JHTDB, an initiative called the Poseidon Project
has been democratizing the LLC4320 (and similar) OGCM data.
Figure 3 illustrates some key features of the Poseidon Project and
the modular workflows it supports. The left panel of Figure 3 is
a screenshot from the public Poseidon Viewer showing surface
relative vorticity in the LLC4320 North Atlantic Ocean. The first
Poseidon Project design goal is for users to access the data with
very low latency (time delay). The Poseidon Viewer achieves this
goal by visualizing the LLC4320 simulation data interactively,
including on mobile devices in a few seconds (try the Poseidon
Viewer interactive LLC4320 visualization tool).
The second Poseidon Project design goal is to provide a simple
software interface for accessing the data. The Poseidon Project (like
the JHTDB) is hosted on SciServer, which is a collaborative cloud
environment for analysis of extremely large datasets (Medvedev
et al., 2016). The SciServer supports Jupyter notebooks for data
analysis. The middle panel of Figure 3 shows a screenshot of a
SciServer Jupyter notebook using the OceanSpy Python software
to analyze LLC4320 data (Almansi et al., 2019). In this example,
a synthetic hydrographic section is being plotted. The OceanSpy
software is an interface to scalable, open-source tools from the
Pangeo community (which can be used directly in SciServer, for
example, by using xarray without the OceanSpy interface). The
right panel of Figure 3 shows trajectories of drifting particles in
the LLC4320 surface currents. The trajectories were computed in
a SciServer Jupyter notebook using the Seaduck Python software
(Jiang et al., 2023).
The third Poseidon Project design goal is to focus on final com-
putation and rendering of high-quality figures. SciServer achieves
these goals by performing data-proximate, lazy calculations (no
data downloads are necessary, although they are possible) and pro-
viding a robust, stable, fully functional programming environment
in the cloud. Thus, anyone with internet access can interact with
the LLC4320 data, make calculations, and produce publication-
ready figures. This is another sense in which the simulation data
are being “democratized” (made open to everyone).
INTERACTIVE
VISUALIZATION
SYNTHETIC OCEAN
OBSERVATION
LAGRANGIAN
TRAJECTORIES
FIGURE 3. The Poseidon Project makes high-resolution OGCM solutions publicly available, such as the global LLC4320 simulation. Users can interact with
the data using a mobile-friendly, interactive visualization tool and Python application programming interface software such as OceanSpy (Almansi et al.,
2019), which samples the OGCM data using synthetic oceanographic instruments, along with Seaduck (Jiang et al., 2023), which computes Lagrangian tra-
jectories. The data can also be accessed using Pangeo tools such as xarray. Run the Poseidon Viewer interactive LLC4320 visualization tool.
FIGURE 2. Growth over time of the number of papers per
year citing the LLC4320 global OGCM and the Johns Hopkins
Turbulence Database (JHTDB). Note that the y-axis is logarith-
mic (the τ2× doubling time for the annual JHTDB citations is
3.0 yr). The data are taken from the LLC4320 and JHTDB web-
sites as of March 2025.