Exploring Argo Data Before You Write Code

OceanGraph helps you explore Argo float data before you start writing code.

When you begin oceanographic research, you are often told to “look at the data,” but it is not always clear what to look for or how to interpret what you see.

OceanGraph is a web-based visualization platform for searching Argo float profiles, inspecting trajectories and selected profile graphs, and viewing time-series vertical sections and θ–S diagrams. It helps you build intuition and develop research questions without dealing with NetCDF files or complex scripts.

Open OceanGraph to explore real Argo profiles while reading this guide.

With OceanGraph, you can:

• View a selected profile graph and compare downloaded JSON profiles in Analysis Lab
• Examine water mass characteristics using θ–S diagrams
• Trace float trajectories to understand spatial context
• Identify patterns and anomalies that may lead to research questions

OceanGraph is not a replacement for numerical analysis or scripting. It is designed to support early-stage exploration and interpretation, not to produce final results for publication.

Start Exploring

Browse the App Guide

Read the Articles

Features

For everyone

• Search Argo floats worldwide by region and time (up to a 30-day date range)
• Search only profiles that include at least one BGC parameter
• Search by WMO ID for direct access to specific floats
• Track individual float trajectories
• Visualize time-series vertical sections of Argo float data

Note: Requests are rate-limited. Signing in does not increase an endpoint’s request limit.

For signed-in users

All free features, plus:

• Search Argo floats with an extended date range (up to 90 days)
• Visualize vertical profiles of temperature, salinity, oxygen, and supported BGC parameters
• View mixed layer depth from profile data
• View SOM (subsurface oxygen maximum) depth and its corresponding oxygen values
• Generate θ–S diagrams from up to 500 search-result profiles or up to 500 cycles in one trajectory
• Explore temperature, salinity, and six BGC variables down to 1000 dbar in a 3D view using up to 500 profiles in a selected region
• Download observation profile data for custom analysis
• Save screenshots of search results and visualizations
• Store up to 10 search bookmarks for repeated use
• Store up to 10 profile bookmarks for later reference or comparison
• Cluster up to 500 search-result profiles or up to 500 cycles in one trajectory
• Browse Ocean Basins and Mode Waters views in Visual Lab
• Upload and compare up to 30 custom JSON profiles in Vertical Profiles (desktop browsers only)

App Guide

This guide helps you start using OceanGraph, find the workflow that matches your goal, and understand the data behind the displays.

OceanGraph is a web application for searching and analyzing ocean observation data collected by the International Argo Program. You can search for temperature, salinity, dissolved oxygen, and other measurements from Argo floats based on geographic and temporal criteria, and explore the ocean state through various visualization and analysis features.

Open OceanGraph to follow this guide using the live application.

Start Here

Quick Start: Your First 10 Minutes

Follow one guided session from a map search to profile context, a float trajectory, a time-series vertical section, and an optional signed-in analysis.

Choose a Workflow

Usage Guide

Use the feature guides for one of OceanGraph’s three main workflows:

• Search and analyze profiles with Basic Features
• Browse precomputed regional views in Visual Lab
• Compare your own Argo-format JSON profiles in Analysis Lab

See Features for the current sign-in requirements and usage limits.

Understand the Data

Data Guide

Check the Argo data source, OceanGraph’s filtering policy, and limitations that affect how profiles, derived metrics, and missing areas should be interpreted.

Quick Start: Your First 10 Minutes

Follow this path from a map search to one float’s trajectory and an optional signed-in analysis.

Open OceanGraph and follow along.

Before You Start

You can complete steps 1–3 without an account. Profile graphs, analyses, and derived data layers require signing in.

See Features for the complete access and usage-limit reference.

Step 1: Search the map

1. Set a Date Range (anonymous: up to 30 days; signed in: up to 90 days).
2. Set the Geographic Bounds by interacting with the map.
3. Optionally check Only profiles with BGC to keep profiles with biogeochemical measurements.
4. Run the search.

If you already know a float, enter its WMO ID in the Profile Details panel to load all of its profiles.

See Search and Bookmark for details.

Step 2: Select a marker

Signed-in users can also inspect the selected profile graph. Start with the overall shape of temperature or salinity and note the surface layer, the main gradient, and the deeper structure before moving to a multi-profile view.

Step 3: Follow One Float (Trajectory and Section)

1. In the map command bar, turn on Trajectory to load every cycle along the selected float’s trajectory.
2. Open Analysis and select View section to see the time-series vertical section.

The dashed line marks the selected profile. Gray or blank areas indicate missing or insufficient data, not zero values.

See Trajectory and Time-Series Vertical Section.

Step 4: Choose an Analysis — Signed In

Open Analysis and select Generate θ–S to compare temperature-salinity structure, or Run clustering to group profiles by vertical structure. On narrower layouts, open Tools first.

With Trajectory off, these analyses use the current search results; with it on, they use all loaded cycles for the selected float. The limit is 500 profiles or cycles, so a WMO with more than 500 cycles cannot be analyzed. Analysis shows why an action is disabled.

See θ–S Diagram and Clustering.

Continue With Derived Data Layers

Signed-in users can choose one Data layer to color map markers:

• MLD: mixed layer depth; works with core Argo profiles.
• SOM: subsurface oxygen maximum; requires dissolved oxygen data from BGC profiles.
• Mode Water: detected layer thickness for a selected type, such as NPSTMW.

Gray or no-data markers indicate that a valid result is unavailable. MLD and SOM can also appear on the matching section chart. See Limitations for missing charts or blank areas.

Where to go next

• Review the full Usage Guide and choose the workflow that matches your goal.
• Compare your own Argo-format JSON files in Vertical Profiles (signed-in, desktop only).
• Browse precomputed views in Visual Lab.
• Read the Articles for background on Argo floats, T-S diagrams, BGC parameters, and more.

Usage Guide

This section guides you through OceanGraph’s core functionality, from searching for Argo float data to visualizing and analyzing oceanographic observations.

Open OceanGraph to follow these workflows with real Argo data.

If this is your first session, begin with Quick Start: Your First 10 Minutes. For sign-in requirements and current limits, see Features.

OceanGraph provides three main workflows:

Basic Features

Search for profiles, inspect individual floats and trajectories, and open analysis views based on the current search results.

Visual Lab

Browse precomputed views of large-scale ocean patterns, including Ocean Basins and Mode Waters.

Analysis Lab

Work with your own Argo-format profile data. The current Vertical Profiles tool compares uploaded JSON profiles on desktop browsers.

Basic Features

These guides cover the search-based OceanGraph workflow, from finding profiles to opening visualizations and derived data layers.

Open OceanGraph to try these features in the live app.

For a guided first session, use Quick Start: Your First 10 Minutes. See Features for sign-in requirements and current limits.

• Search and Bookmark: find profiles by place, time, WMO ID, and BGC availability, then bookmark searches or profiles when signed in.
• Trajectory and Time-Series Vertical Section: follow one float and examine changes across its sequence of profiles.
• θ–S Diagram: compare potential temperature and absolute salinity relationships in search results or one trajectory.
• 3D View: select a region and compare horizontal temperature, salinity, and BGC distributions across pressure levels.
• Clustering: group search-result profiles or trajectory cycles by vertical structure for exploratory comparison.
• Mixed Layer Depth (MLD): color profiles by the automatically derived mixed layer depth.
• Subsurface Oxygen Maximum (SOM): inspect automatically detected subsurface oxygen maxima in BGC profiles.
• Mode Water Data Layer: compare profile-level mode water detections and layer thickness.

Search and Bookmark

Search Methods

Control Panel

With the control panel hidden, Search this area searches the visible map area using the current filters. On narrower layouts, signed-in commands are grouped under Tools.

Filter Data Panel

Search dates run from October 1999 to the present, in UTC. The maximum date range is 30 days anonymously or 90 days when signed in. The map sets the geographic bounds.

Only profiles with BGC includes profiles with at least one supported BGC parameter: dissolved oxygen, chlorophyll, nitrate, backscattering, pH, downwelling irradiance at 490 nm, or PAR. Irradiance at 490 nm is searchable and downloadable but has no in-app chart.

Profile Details Panel

A WMO ID search loads all profiles for that float. Signed-in users can download the selected profile’s data from this panel.

Using Bookmarks

Signed-in users can save up to 10 searches and 10 profiles with Bookmark search and Bookmark profile. Search bookmarks store filters; profile bookmarks store a float and cycle.

Reopen saved items from Menu > Bookmarks.

Titles allow up to 64 characters and notes up to 200.

Results and Analysis Limits

θ–S Diagram and Clustering accept up to 500 profiles. For a larger search, the corresponding Analysis item shows the current count and remains disabled; OceanGraph does not sample or split oversized inputs. Requests are also rate-limited; signing in does not increase an endpoint’s request limit.

For 3D View, the 500-profile limit applies to the selected rectangle, so a larger loaded set can still be narrowed on the map.

Related Reading

For guidance on choosing between regional, date-based, WMO ID, and BGC searches, read Finding Argo Float Profiles by Location, Time, and WMO ID in OceanGraph Articles.

Trajectory and Time-Series Vertical Section

Use a time-series vertical section to compare oceanographic parameters by pressure and profile cycle along one float’s trajectory.

Accessing Time-Series Vertical Sections

Select a profile, turn on Trajectory, then open Analysis → View section (under Tools on narrower layouts). The section’s parameter selection is independent of the Profile chart.

The Date Range continues to show the filter used for the original search. Trajectory then loads all published cycles for the selected WMO ID, so Profile Details can show a cycle outside that range.

Turning Trajectory off restores the profile that was selected when it started, even if you moved to another cycle. A new search clears that saved selection. Toggling Trajectory closes the previous θ–S display and cancels an active θ–S or Clustering job.

Comparing Profiles

With Trajectory on, ← / → moves in cycle-number order, skipping missing cycles. You can also click or drag across the section to select a profile directly.

Signed-in users can also open θ–S from Analysis while Trajectory is on. θ–S uses every cycle in the selected WMO trajectory and can stay open alongside the section, highlighting the selected cycle.

You can also generate a 3D view from loaded trajectory profiles within a rectangle. Toggling Trajectory cancels an unfinished 3D selection, but preserves generation already in progress and the latest successful result.

Interpret the Section

• The vertical section is linked with the vertical profiles in Profile Details, and the position of the selected profile is shown with a dashed line.
• Every parameter uses the same 0–2000 dbar coordinate at 5 dbar intervals. The 500 and 1000 dbar views crop this coordinate, so colors and MLD/SOM data-layer points remain aligned. Values are not extrapolated above the shallowest finite observation.
• Missing areas mean unavailable, masked, or insufficiently supported values, not zero. Interpolation is limited to pressure within a profile; missing cycles remain gaps.
• A parameter with a published section displays its chart. If individual profiles contain usable values but adjacent cycles do not provide enough support to draw a section, the parameter remains selectable and the section area explains the limitation. A parameter with no usable profile data is disabled.
• Signed-in users can show MLD or SOM with Data layer. Points mark valid results, and lines connect consecutive cycles only. Gaps indicate missing cycles or unavailable results; the lines are visual guides, not interpolation through time.

Related Reading

For help interpreting patterns, gaps, and changes across repeated profiles, read Time-Series Vertical Sections in Oceanography Explained in OceanGraph Articles.

θ–S Diagram

The θ–S diagram compares potential temperature and absolute salinity for either the current search results or one float’s loaded trajectory.

Open the Diagram

Signed-in users can open Analysis → Generate θ–S (under Tools on narrower layouts). With Trajectory off, the diagram uses the current search results; with it on, it uses all cycles for the selected float. The limit is 500 profiles or cycles.

OceanGraph does not sample or split oversized inputs, so a trajectory over 500 cycles cannot be analyzed.

The latest result can be reopened without regeneration until you reset the search, leave Explore, or sign out.

With Trajectory on, θ–S can stay open alongside the time-series vertical section, and both follow the selected cycle. Only one analysis job (θ–S, Clustering, or 3D view) can run at a time.

Read the Display

• Background contours show potential density anomaly referenced to 0 dbar (σ₀). OceanGraph converts potential temperature to Conservative Temperature internally for this TEOS-10 density calculation; the plotted axes do not change.
• Each profile line uses pressure rows with a finite temperature-salinity pair. Profiles with fewer than two pairs are omitted.
• Unselected profiles use cluster colors, with excluded or unassigned profiles shown in gray. This is independent of the map’s Data layer.
• The selected profile appears in front as a thicker blue line.

Use the diagram to compare water-mass structure and mixing patterns. For a conceptual explanation, see T-S Diagrams in Oceanography Explained.

3D View

The 3D view stacks horizontal maps of potential temperature (θ), absolute salinity (S), and six BGC variables down to 1000 dbar. Use it to compare water properties across depths within a selected region.

Generate a View

Sign in and load profiles. With Trajectory on, the view uses its loaded cycles.

Open Analysis → Generate 3D view (under Tools on narrower layouts), draw a rectangle on the map, and generate the view. The selection snaps to a 0.5° grid and stops expanding at the size limit. While selecting, dragging outside the rectangle redraws it instead of panning the map.

Select 1–500 profiles within the rectangle; only currently loaded profiles are used. The limit applies to the selected region, even if more than 500 profiles are loaded.

Changing the loaded data or toggling Trajectory cancels an unfinished selection.

Only one analysis job can run at a time.

Read the View

Surface represents 10 dbar; deeper levels run from 100 to 1000 dbar at 100 dbar intervals. Variables with no valid values at any calculated pressure are disabled.

Dots show values derived from profiles at each pressure, and vertical lines connect the same profile.

With Boost contrast off, each variable uses one color scale across all layers for comparing values across depths. Palettes match vertical sections, but their value ranges may differ.

Turn Boost contrast on to explore small differences within the selected layer. The palette spans that layer’s minimum and maximum values, using the Selected layer scale for its dots, surface, and contours.

Faint background layers keep the normal shared scale, so the same color can mean different values on another layer or after changing depth. Even a small value range fills the palette; color differences do not establish scientific significance or identify anomalies. Contrast does not change values or fill missing areas.

Surface and profile values together set the contrast scale, including layers with only dots. A constant layer uses one color and no contours.

The count below the plot includes only valid profiles for the current variable and pressure. Observation period covers all selected profiles, including those missing values for the current variable. It shows the earliest and latest UTC observation dates.

Levels and variables with only dots remain selectable even when there is insufficient data for a surface.

Surfaces show estimates only near valid observations for the selected variable and pressure. Areas farther away remain blank, including gaps between observation groups. See 3D view limitations for the distance limit, interpolation method, and accuracy limitations.

Navigate and Reopen

Use ↑ / ↓ for shallower / deeper levels and ← / → for the previous / next available variable. Each newly opened or reopened view starts with Boost contrast off.

Reopen 3D view restores the latest result without recalculation. Toggling Trajectory, or a failed or cancelled generation, keeps the latest successful result. Resetting the search, leaving Explore, or signing out clears it. Image and data export are not available from this view.

Clustering

OceanGraph provides an experimental feature that groups Argo profiles by similarities in their vertical structure and location.

Accessing Clustering

Signed-in users can open Analysis → Run clustering (under Tools on narrower layouts). With Trajectory off, clustering uses the current search results; with it on, it uses all cycles for the selected float. The limit is 500 profiles or cycles.

OceanGraph does not sample or split oversized inputs, so a trajectory over 500 cycles cannot be analyzed.

Only one analysis job (θ–S, Clustering, or 3D view) can run at a time.

You can keep or change your Data layer while clustering runs. A failed, cancelled, or timed-out analysis leaves your current selection unchanged.

Interpreting Results

On success, including after Retry, Data layer switches to None to show the cluster colors. You can select another layer afterward.

• Colored markers indicate profiles assigned to clusters.
• Gray markers indicate profiles excluded from clustering because they did not satisfy the required variables or depth coverage.
• The cluster labels are exploratory groups, not confirmed water-mass names.

What the Grouping Uses

• Only pressure rows with a finite temperature-salinity pair are used.
• Profiles are compared on a shared 100 dbar grid from 200 dbar to an upper depth chosen from the input set, with 1000 dbar as the maximum. Profiles that do not cover that range are excluded.
• Temperature and salinity at each depth are standardized and combined with latitude and longitude.
• The number of clusters is selected automatically, up to six. A single eligible profile or identical inputs form one group.

Because the comparison depth and input population depend on the current selection, cluster numbers from different searches are not directly comparable.

Mixed Layer Depth (MLD)

OceanGraph derives a mixed layer depth exploration indicator from potential temperature, absolute salinity, and potential density anomaly referenced to 0 dbar (σ₀).

Use MLD

After signing in and loading profiles, choose Data layer → MLD (under Tools on narrower layouts).

Profiles without a valid MLD are gray.

The vertical profile shows MLD as a cyan dashed line when the selected observation’s curve is displayed and MLD falls within 0–Max (dbar). The line marks the same depth across displayed variables; Trajectory and a section are not required.

When Trajectory and a section are open, valid MLD values are shown as cyan points. Lines connect consecutive profile cycles only; they do not bridge missing cycles or imply interpolation through time.

Calculation

OceanGraph calculates three threshold crossings relative to the profile value at 10 dbar and uses the shallowest crossing.

Each crossing is linearly interpolated between the pressure rows that bracket its threshold and recorded to 0.01 dbar. Absolute salinity and potential temperature are derived with TEOS-10; Conservative Temperature is used only as an intermediate value for the density calculation.

The calculation requires at least three finite temperature-salinity rows, including two at 50 dbar or shallower. The shallowest paired row must be at 30 dbar or shallower and the profile must reach 10 dbar. If the first paired row is between 10 and 30 dbar, it supplies the reference values. If no threshold is crossed, MLD is undefined.

Map tooltips, vertical profiles, and section data layers use pressure in dbar. The color scale is a relative visual aid, and the result is an automatic threshold-based indicator rather than a guaranteed physical boundary. Because SOM selection begins below MLD, an MLD change can also change the reported SOM.

Subsurface Oxygen Maximum (SOM)

OceanGraph detects a supported local maximum in a profile’s dissolved oxygen measurements. SOM is an exploration indicator for upper-ocean oxygen structure, not a guarantee that every physical maximum will be detected.

Use SOM

After signing in and loading profiles, choose Data layer → SOM (under Tools on narrower layouts). SOM requires dissolved oxygen data; Only profiles with BGC helps narrow the search, but does not guarantee oxygen availability.

Profiles without oxygen or a valid SOM are shown as no-data markers. Marker tooltips show SOM pressure and oxygen.

The vertical profile shows SOM as a purple dashed line when the selected observation’s curve is displayed and SOM falls within 0–Max (dbar). The line marks the same depth across displayed variables; Trajectory and a section are not required.

On an oxygen section, valid SOM values appear as purple points connected only across consecutive profile cycles. Gaps indicate a missing cycle or a profile where SOM was not detected or could not be calculated.

Detection

• With a valid MLD, candidates must be deeper than MLD and no deeper than 300 dbar. Without MLD, the range is 30–300 dbar. Profiles with MLD at 300 dbar or deeper are not assigned SOM.
• Detection uses finite source oxygen observations after quality masking and numeric-range checks. Internal gaps are interpolated only to evaluate peak shape; downloaded Profile JSON is not filled.
• A candidate must be an observed local maximum with at least 5 µmol/kg prominence and enough observed support around the peak. Endpoints, monotonic profiles, weak or unsupported narrow peaks, and peaks created only by interpolation are not reported.
• Candidates are ranked by prominence, oxygen value, then shallower pressure. When MLD exists, a supported peak within 100 dbar below MLD is preferred when available.

The result stores pressure in dbar and dissolved oxygen in µmol/kg. If no candidate satisfies the criteria, SOM is undefined.

Mode Water Data Layer

OceanGraph can color search-result map markers by profile-level mode water detection. This helps you inspect where individual profiles match a selected mode water type, and how thick the detected layer is.

This data layer is separate from Visual Lab > Mode Waters. The data layer works on the profiles in your current search results, while Visual Lab shows precomputed three-month summaries and time series.

Accessing the Data Layer

After signing in and loading profiles, choose a mode water type such as NPSTMW from Data layer (under Tools on narrower layouts).

Marker Colors

Profiles with the selected mode water are colored by detected layer thickness; others are shown as no-data markers.

Color represents thickness and should be read as a relative visual cue, not as a separate classification variable.

Supported Mode Water Types

The region column reflects OceanGraph’s default advection processing scope, which searches broader areas that can include advected mode water signals. Density ranges use potential density anomaly referenced to 0 dbar (σ₀) in kg/m³.

All listed mode water types use a maximum potential vorticity threshold of 2 × 10⁻¹⁰ m⁻¹s⁻¹ and a minimum detected layer thickness of 10 m.

Detection Summary

OceanGraph checks quality-controlled, interpolated potential temperature and absolute salinity against the configured region, density, potential-vorticity, and minimum-thickness criteria. Where potential vorticity cannot be calculated, the density criterion is used alone. Core depth is the midpoint of the detected layer after converting its top and bottom pressures to depth; it is not the depth of minimum potential vorticity. A profile can contain more than one detected type, but the map displays only the type selected in Data layer.

Interpreting No-Data Markers

A no-data marker does not necessarily mean the profile is unusable. It means the selected mode water type was not detected for that profile under OceanGraph’s current automatic criteria. Common reasons include:

• The profile is outside the selected mode water’s geographic bounds
• The density or potential vorticity criteria were not met
• The matching layer was thinner than the 10 m minimum required thickness
• The profile did not have enough valid data after quality control and interpolation

Mode water detection is intended as an exploration aid. For research-grade classification, inspect the original profile structure and apply the criteria appropriate to your study.

Visual Lab

Visual Lab shows precomputed views of large-scale ocean patterns from Argo profiles. It is available to signed-in users from Menu > Visual Lab.

Open OceanGraph to browse Visual Lab views in the live app.

• Ocean Basins: annual mean potential temperature and absolute salinity at 10 dbar for five major ocean basins since 1998.
• Mode Waters: three-month thickness statistics and profile counts for detected mode water layers.

Ocean Basins

Ocean Basins shows annual average potential temperature and absolute salinity at 10 dbar for the North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian Ocean.

Accessing Ocean Basins

Sign in and open Menu > Visual Lab > Ocean Basins.

Read the Graphs

The series runs from 1998 to the present and uses Argo profile measurements interpolated with the Akima method.

Interpretation Notes

• Early years have fewer Argo profiles than recent years, so check profile counts before comparing long-term values.
• The annual averages support exploratory visualization and education. Use original Argo data and a reproducible analysis workflow for publication-grade results.

Mode Waters

Mode Waters summarizes detected mode water layers by three-month period, with profile counts and thickness statistics.

To inspect the same detections on individual map markers, use the Mode Water Data Layer.

Accessing Mode Waters

Sign in and open Menu > Visual Lab > Mode Waters.

Results Display

Mean Thickness is the average of the three-month median thickness values shown in the time series.

Graphs

Both graphs use three-month periods from 2001 onward.

• Time series: median thickness (solid blue line) with lower and upper quartiles (dashed gray lines)
• Profile count: number of profiles containing mode water in each period (blue bars)

Included Profiles

Detection uses the geographic bounds, density range, and potential vorticity threshold displayed on screen. Only profiles inside that region that reach at least 500 dbar and contain enough finite pressure, temperature, and salinity values are analyzed. Detected layers must be at least 10 m thick. Where potential vorticity cannot be calculated at a depth, the density criterion is used alone. These automatic criteria support exploration; they do not guarantee a research-grade water-mass classification.

Three-Month Periods

Periods are labeled by month initials (DJF, MAM, JJA, SON), not by hemisphere-specific season names. DJF uses the year of January and February: 2024 DJF covers December 2023 through February 2024.

Related Reading

For background on mode-water formation and interpretation, read What Is Mode Water? in OceanGraph Articles.

Analysis Lab

Analysis Lab is available to signed-in users from Menu > Analysis Lab in OceanGraph.

The desktop-only Vertical Profiles tool compares uploaded Argo-format JSON profiles and exports charts with an optional note.

Vertical Profiles

Compare uploaded Argo-format JSON profiles of temperature, salinity, dissolved oxygen, and supported optional BGC variables by depth.

Missing values (null) stay missing; charts connect two or more finite cells with straight lines.

Access and Limits

Open Menu > Analysis Lab > Vertical Profiles after signing in on a desktop browser. You can upload up to 30 JSON files; uploading a matching filename replaces the previous file.

Compare Profiles

• Highlight: hover over a visible row or near a chart line to highlight the profile across all charts.
• Pin: click a row name or line to keep its highlight while exploring other variables. Esc clears the pin and tooltip. Pinning does not change which profiles are visible.

Tooltip values come from a nearby real sample, without interpolation. While pinned, other lines show only their identity.

Each file keeps its color and line style, including after same-name replacement. Profiles and visibility choices are kept when you leave the page.

Notes and Download

Download ZIP saves the checked profiles as one PNG per chart type, plus the Add a note (optional) text as note.txt.

PNG files use normal line styles without highlights, tooltips, or the Profiles list. Clear All also clears the note.

Supported JSON Format

Each JSON file must contain the following keys:

{
  "pressure": [ ... ],
  "potential_temperature": [ ... ],
  "absolute_salinity": [ ... ],
  "oxygen": [ ... ],
  "wmo_id": "2902447",
  "cycle_number": 17
}

• "pressure": array of numbers (required, must not be empty)
• "potential_temperature": array of numbers or nulls (required; if non-empty, same length as pressure)
• "absolute_salinity": array of numbers or nulls (required; if non-empty, same length as pressure)
• "oxygen": array of numbers or nulls — dissolved oxygen concentration (μmol/kg) (required; if non-empty, same length as pressure)
• "wmo_id": string or number (required, up to 20 characters after conversion to text)
• "cycle_number": number (required)

Optional BGC keys can also be included:

• "chlorophyll": array of numbers or nulls — chlorophyll-a (mg/m³) (same length as pressure, if present)
• "nitrate": array of numbers or nulls — nitrate (μmol/kg) (same length as pressure, if present)
• "bbp700": array of numbers or nulls — particulate backscattering at 700 nm (m⁻¹) (same length as pressure, if present)
• "ph": array of numbers or nulls — in-situ pH (same length as pressure, if present)
• "irradiance490": array of numbers or nulls — downwelling irradiance at 490 nm (W/m²/nm) (same length as pressure, if present). This key is accepted, but it is not displayed as a chart in the current interface.
• "par": array of numbers or nulls — photosynthetically available radiation (μmol/m²/s) (same length as pressure, if present)

Any additional keys will be ignored. Files that do not follow the required structure or fail validation will be skipped during upload.

Related Reading

For a beginner-friendly explanation of profile context, variables, quality information, and vertical structure, read How to Read Argo Float Data for Beginners in OceanGraph Articles.

Data Guide

This section explains where OceanGraph data comes from, how profiles are filtered, and what limitations to keep in mind when interpreting results.

Open OceanGraph to inspect the live dataset while reading this guide.

OceanGraph aims to refresh its data weekly. Update notices and current availability are posted on X (Twitter) at @OceanGraphJP.

Data Source

OceanGraph uses Argo float data and associated metadata provided by the International Argo Program and the national programs that contribute to it. These data are made freely available through the Argo Global Data Assembly Centre (Argo GDAC) and are a core component of the Global Ocean Observing System (GOOS).

For data access, OceanGraph retrieves Argo GDAC files via the public AWS S3 distribution (Open Data on AWS), which is synchronized with the GDAC holdings and updated on a daily basis. This S3-based access method is used to improve download reliability and performance, while preserving the original GDAC directory structure and dataset contents.

References:

• International Argo Program: https://argo.ucsd.edu
• OceanOPS Argo Information Centre: https://www.ocean-ops.org/board?t=argo

Acknowledgement “These data were collected and made freely available by the International Argo Program and the national programs that contribute to it. (https://argo.ucsd.edu, https://www.ocean-ops.org). The Argo Program is part of the Global Ocean Observing System.”

DOI / Citation Argo (2000). Argo float data and metadata from Global Data Assembly Centre (Argo GDAC). SEANOE. https://doi.org/10.17882/42182

Related Reading

For an introduction to how Argo floats operate and why their repeated profiles matter, read What is Argo Float? A Complete Guide to Ocean Observation Data in OceanGraph Articles.

Data Filtering Policy

OceanGraph publishes a quality-controlled subset of Argo GDAC profiles. A profile can be absent because of its file type, conflicting WMO IDs, quality flags, required variables, pressure coverage, or a conversion failure. Missing data in a published profile are represented as missing values, not as zero.

Profile and File Selection

• Core real-time (R) and delayed-mode (D) files enumerate profile cycles; D is preferred when both exist.
• If ascending core profiles for the same WMO ID occur under multiple Data Assembly Centres (DACs), OceanGraph excludes all profiles for that WMO ID to prevent mixing observations from different floats. Once the source conflict is resolved and reflected in a subsequent data update, those profiles become eligible for publication again, subject to the usual quality checks.
• A synthetic profile is preferred when available (SD before SR) so core and BGC measurements share one pressure axis. If it fails a known data or quality check, the corresponding core profile may still be published without BGC data.
• B-files (BR / BD) and drift profiles whose cycle suffix ends in D are not used.
• If a core or synthetic file contains several profiles, OceanGraph selects the unique profile whose VERTICAL_SAMPLING_SCHEME starts with Primary sampling:. If the variable is absent or every value is empty, index 0 is used in Argo profile order. A file with non-empty sampling-scheme values but no unique Primary profile is rejected; a rejected synthetic file can still fall back to its independently checked core file. Quality, direction, data mode, resolution, observation count, and pressure span are not used to compare sampling schemes. If the selected Primary fails a later check, OceanGraph does not switch to Secondary or Near-surface sampling.

Profiles require identifiers, date, position, pressure, temperature, salinity, and the corresponding core QC fields. Synthetic profiles also require the fields that identify each parameter’s processing mode. BGC parameters are optional; a profile can therefore appear in search results while some BGC charts are unavailable.

Supported BGC parameters are dissolved oxygen, chlorophyll-a, nitrate, particulate backscattering at 700 nm, pH, downwelling irradiance at 490 nm, and photosynthetically available radiation (PAR). Irradiance at 490 nm is searchable and downloadable but does not currently have an in-app chart.

Source Data and Quality Control

For pressure, temperature, and salinity, OceanGraph uses the ADJUSTED set only when all three adjusted variables and their QC arrays contain finite data. Otherwise it uses the raw set. Each BGC parameter makes the adjusted-or-raw choice independently; masking after that choice does not trigger another fallback.

• Date and position QC must be 1, 2, or 8.
• At least 80% of pressure, temperature, and salinity QC values must be 1, 2, or 8.
• Retained pressure rows must be finite, between 0 and 2000 dbar inclusive, and have pressure QC 1, 2, or 8.
• Temperature or salinity can be missing on an otherwise retained pressure row. At least three rows must contain finite pressure, temperature, and salinity with all three QC values in 1, 2, or 8, and the shallowest such row must be at or above 50 dbar (a pressure value no greater than 50 dbar).
• For BGC parameters, selected-source QC 4 and 9 are masked. Other retained QC codes have different meanings and should still be checked in the source data before scientific use.

Longitude is normalized to [-180°, 180°] before rounding. Passing position QC does not guarantee that every reported position is suitable for a particular analysis.

Missing Cells and Numeric Limits

All parameter arrays align with the finite pressure array. A missing cell becomes JSON null; a parameter with no finite values becomes an empty array. Pressure-only profiles are not published, but a profile can remain available when only a BGC parameter survives alongside pressure.

After source and QC selection, finite values outside these inclusive ranges become null. They are not clamped, filled, or retried from another source.

At duplicate pressures, OceanGraph keeps one row deterministically, preferring joint temperature-salinity support and then salinity support. Values from discarded duplicate rows are not merged into the retained row.

Pressure Coverage and Conversion

After the minimum joint-observation count and shallow-coverage checks, profiles with excessive gaps between adjacent joint, acceptable-QC temperature-salinity observations are excluded. The allowed gap increases with pressure because deep observations are typically spaced farther apart. No minimum pressure span or required maximum pressure is imposed.

In-situ temperature is converted to potential temperature, and practical salinity to absolute salinity, with the TEOS-10 Gibbs SeaWater toolbox. A cell-level conversion failure remains null; a failure that removes required joint support can exclude the profile.

Profile JSON does not interpolate missing cells. Section generation, Akima output, and server-side analyses may interpolate finite values inside a parameter’s observed pressure range, but do not extrapolate beyond it or fill missing profile cycles.

Published values are rounded to the following precision:

Limitations

Missing Values in Vertical Section Charts

1. Masked Areas Without Original Data

   When generating time-series vertical section charts, each profile is interpolated vertically onto a common pressure grid only between finite observations. OceanGraph does not interpolate along the cycle direction. A missing cycle therefore remains a missing column instead of becoming a smooth estimate between distant observations.

   In the chart, these masked areas appear as uncolored gaps in the vertical section.

   

2. Sparse Data Due to Quality Control

   After processing, some parameters can have finite values in isolated profiles but no pair of adjacent cycles with enough shared vertical support to form a contour cell. In that case OceanGraph does not publish an SVG for that parameter. The interface distinguishes this “profile data exists, but no drawable section” state from a parameter that has no profile data at all.

3. BGC Parameter Charts May Have More Missing Areas

   Vertical section charts in the OceanGraph interface are also available for BGC parameters (dissolved oxygen, chlorophyll, nitrate, backscattering, pH, and PAR). Because only a subset of Argo floats carry BGC sensors, these variables often contain more null cells or isolated cycles than temperature and salinity. Finite BGC measurements are retained independently of missing temperature or salinity cells, but a section still requires adjacent-cycle support to be drawable.

   PAR observations are typically concentrated in the surface layer (roughly 0–200 dbar), so deeper portions of PAR section charts commonly appear as missing areas.

   Note also that of the two irradiance parameters (DOWN_IRRADIANCE490 and DOWNWELLING_PAR), only PAR is displayed as an in-app chart. Downwelling irradiance at 490 nm can make a profile match the “Only profiles with BGC” search filter and is included in downloadable profile data, but it does not have a corresponding in-app visualization.

3D View

The 3D view combines quality-filtered profile values into horizontal surfaces without additional QC. Keep these limits in mind:

• Each variable uses its own valid observations, so BGC values remain available where θ or S is missing. Interpolation stays within each profile’s observed pressure range for that variable; deeper PAR layers commonly remain missing.
• A surface needs valid values at three or more distinct locations that do not lie on one straight line. Repeated profiles at the same location do not add locations.
• Within the area enclosed by valid locations, values are interpolated linearly. Outside that area, the nearest valid value is extended as extrapolation. Both are displayed only at grid points within 250 km of a valid location for that variable and pressure. Distance uses the selected region’s central latitude to scale longitude.
• Areas beyond this limit remain blank, even inside the area enclosed by observations. Blank areas do not mean that the variable is zero or that no water is present.
• The distance limit controls display coverage; it is not a scientific correlation length or an accuracy guarantee. Distant observations can still influence an interpolated value near a valid location.
• Sparse observations and the 0.5° grid can produce coarse contours. Grid spacing and smooth-looking colors do not indicate measurement accuracy.
• Boost contrast expands even small differences across the full palette without changing values or missing areas; colors do not establish scientific significance or identify anomalies. Its scale applies only to the selected layer, so matching colors across layers or after changing depth need not mean matching values.
• Land and seafloor boundaries are ignored.
• Observations from different times are combined without time correction. This exploratory view does not reconstruct a single-time or period-average ocean field. Seasonal and other changes over time can appear as spatial differences, especially in long WMO histories. Check the displayed observation period for every view, including those from geographic searches.
• Horizontal proportions approximate geographic distances, but the pressure direction is exaggerated for readability. The axes do not share one physical distance scale.

Derived Metrics and Mode Water Detection

Derived metrics such as MLD, SOM, and mode water detections are calculated automatically from profiles that pass OceanGraph’s data processing checks. A no-data marker can mean that the source profile was insufficient for the calculation, or that the target feature was not detected under the current criteria.

Mode water detection uses fixed geographic, density, potential vorticity, and minimum-thickness criteria. The default geographic scope is configured to cover broader areas that can include advected mode water signals, but it is still an automatic bounding-box screen and may not cover every scientifically relevant signal. Treat the map data layer and Visual Lab summaries as exploration aids, and inspect the original profile structure when a research-grade classification is required.

Educational Articles

OceanGraph Articles explains the oceanographic concepts and research workflows behind the features documented in this guide. The article site maintains its own current recommendations, categories, and complete article list.

Choose a Language

• Browse articles in English
• 日本語の記事を読む

Feature and data pages in this guide also link directly to the most relevant background article when additional explanation is useful.

Legal Guide

This section contains the legal terms governing your use of OceanGraph. Please review these documents carefully before using the application.

Terms of Service

The Terms of Service cover registration where required, prohibited actions, service changes, warranties and liability, and governing law.

Available in:

• English
• 日本語 (Japanese)

Privacy Policy

The Privacy Policy explains how OceanGraph and OceanGraph Articles handle user information.

Available in:

• English
• 日本語 (Japanese)

Terms of Service

The Terms of Service are available in the following languages:

• English
• 日本語 (Japanese)

Terms of Service

Article 1 (Application and Registration)

These Terms of Service (“Terms”) set forth the conditions for the use of the service “OceanGraph” (“Service”) provided by an individual developer (“we” or “us”) and govern the relationship between us and the users of the Service (“Users”).

By using the Service, Users agree to these Terms. Some features require an account and registration of the requested information.

Article 2 (Prohibited Actions and Account Suspension)

Users must not engage in the following acts:

• Acts that violate laws or public order and morals
• Acts that infringe on the rights of third parties
• Registering false information
• Unauthorized access, excessive loads, or other interference with the operation of the Service

We may suspend a User’s account if the User violates these Terms or if suspension is necessary to maintain the security or operation of the Service.

Article 3 (Changes, Suspension, or Termination of the Service and Data)

We may change, suspend, or terminate the Service for maintenance, system failures, disasters, or other operational or technical reasons.

We do not guarantee the continued availability of the Service or the permanent preservation of user data. We may delete stored user data when the Service ends.

We may, when reasonably necessary to maintain the Service, delete accounts and associated data that have been inactive for an extended period without providing individual advance notice to Users.

Article 4 (Warranties and Liability)

We do not warrant the accuracy, completeness, or fitness for a particular purpose of the Service.

If we are liable in connection with the Service, the scope of that liability will be determined in accordance with applicable law.

Article 5 (Governing Law and Jurisdiction)

These Terms are governed by the laws of Japan. Any dispute relating to these Terms or the Service shall be submitted in the first instance to a Japanese court with jurisdiction under applicable law.

利用規約

第1条（適用および利用登録）

本規約は、個人開発者（以下「当方」といいます）が提供するサービス「OceanGraph」（以下「本サービス」）の利用に関する条件を、本サービスの利用者（以下「ユーザー」）との間で定めるものです。

ユーザーは、本サービスを利用することにより、本規約に同意したものとします。一部の機能を利用するには、アカウント登録および所定の情報の登録が必要です。

第2条（禁止事項および利用停止）

ユーザーは、次の行為をしてはなりません。

• 法令または公序良俗に違反する行為
• 第三者の権利を侵害する行為
• 虚偽の情報を登録する行為
• 不正アクセス、過度な負荷その他本サービスの運営を妨害する行為

当方は、ユーザーが本規約に違反した場合、または本サービスの安全な運営に必要な場合、アカウントの利用を停止できます。

第3条（サービスの変更・停止・終了およびデータ）

当方は、メンテナンス、システム障害、災害その他運営上または技術上必要な場合、本サービスを変更、停止または終了することがあります。

当方は、本サービスの継続的な提供やユーザーデータの永続的な保存を保証しません。本サービスを終了する場合、保存されたユーザーデータを削除することがあります。

当方は、本サービスの維持管理上合理的に必要な場合、長期間利用されていないアカウントおよび関連データを、ユーザーに個別に事前通知することなく削除することがあります。

第4条（保証および責任）

当方は、本サービスの正確性、完全性または特定目的への適合性を保証しません。

当方が本サービスに関して責任を負う場合、その範囲は適用法令に従います。

第5条（準拠法・裁判管轄）

本規約は日本法に準拠します。本規約または本サービスに関する紛争は、法令に従い管轄権を有する日本の裁判所を第一審の管轄裁判所とします。

Privacy Policy

The Privacy Policy is available in the following languages:

• English
• 日本語 (Japanese)

Privacy Policy

Last updated: August 3, 2026

This Privacy Policy explains how the individual developer who provides OceanGraph (“we,” “us,” or “our”) handles information in connection with OceanGraph and OceanGraph Articles (collectively, the “Service”).

Article 1 (Information We Collect)

We may collect the following information when providing the Service:

• Account information required for registration and authentication, such as an email address
• Content, contact details, and other information provided through feedback or inquiries
• Usage information such as IP address, usage environment, pages viewed, and interactions with the Service
• Identifiers and settings stored using cookies and similar technologies

OceanGraph does not automatically attach a user ID or email address to feedback content.

Article 2 (Purposes of Use)

We use the information we collect for the following purposes:

• To provide, operate, and maintain the Service
• To verify users and provide authentication features
• To understand usage, improve features and articles, and investigate defects
• To respond to inquiries about the Service and coordinate support
• To prevent and respond to unauthorized use, unauthorized access, and other security issues

Article 3 (Analytics on OceanGraph Articles)

OceanGraph Articles uses Google Analytics 4, provided by Google LLC, only after a user gives consent. We collect information about how articles are viewed and used to understand usage and improve content and navigation. We do not send information entered in the inquiry form to Google Analytics.

OceanGraph Articles stores the user’s analytics choice in the browser. If a user consents to analytics, Google Analytics uses cookies for analytics. Users can change or withdraw consent at any time through “Cookie settings” in the footer of any page. Declining or withdrawing consent does not prevent users from reading articles, switching languages, or following links to OceanGraph.

For details about how Google handles information, see the Google Privacy Policy.

Article 4 (Inquiries on OceanGraph Articles)

We use information submitted through the inquiry form to respond to inquiries and coordinate support. When a user consents to sharing with a partner company, we may share the inquiry and contact details with a suitable partner only to the extent needed to respond.

Article 5 (Service Providers and Disclosure to Third Parties)

We may engage service providers to process information as necessary to provide the Service.

We do not disclose personal information to third parties without the user’s consent, except as permitted by applicable law.

Article 6 (Security)

We take reasonable administrative and technical measures to protect collected information against unauthorized access, loss, alteration, and disclosure.

Article 7 (Contact)

For questions about this Privacy Policy or our handling of user information, please use our contact information.

Article 8 (Changes to This Policy)

We may update this Privacy Policy to reflect changes in law, the Service, or our information practices. If a change is material, we will provide notice through the Service or another appropriate method.

プライバシーポリシー

最終更新日：2026年8月3日

本ポリシーは、個人開発者（以下「当方」といいます）が提供するOceanGraphおよびOceanGraph Articles（以下、総称して「本サービス」といいます）における、ユーザー情報の取扱いについて定めるものです。

第1条（取得する情報）

当方は、本サービスの提供にあたり、次の情報を取得する場合があります。

• アカウント登録・認証に必要なメールアドレス等のアカウント情報
• フィードバックやお問い合わせの際に提供される内容、連絡先その他の情報
• IPアドレス、利用環境、閲覧・操作履歴等の利用情報
• Cookie等に保存される識別子および設定情報

OceanGraphのフィードバック内容に、ユーザーIDやメールアドレスを自動的に付加することはありません。

第2条（利用目的）

取得した情報は、次の目的で利用します。

• 本サービスの提供、運営および保守
• 本人確認および認証機能の提供
• 利用状況の把握、機能や記事の改善および不具合の調査
• 本サービスに関するお問い合わせへの回答および支援の調整
• 不正利用、不正アクセスその他のセキュリティ上の問題の防止および対応

第3条（OceanGraph Articlesのアクセス解析）

OceanGraph Articlesでは、ユーザーが同意した場合に限り、Google LLCが提供するGoogle Analytics 4を使用し、記事の閲覧・利用状況に関する情報を取得します。これらの情報は、記事の利用状況を把握し、内容や導線を改善するために利用します。問い合わせフォームに入力された内容をGoogle Analyticsへ送信することはありません。

OceanGraph Articlesでは、アクセス解析への選択状態をブラウザに保存します。アクセス解析に同意した場合は、Google Analyticsによる解析のためCookieが使用されます。ユーザーは、各ページのフッターにある「アクセス解析の設定」から、いつでも同意を変更または撤回できます。同意しない場合や撤回した場合でも、記事の閲覧、表示言語の切替およびOceanGraphへのリンクは利用できます。

Googleによる情報の取扱いについては、Googleのプライバシーポリシーをご確認ください。

第4条（OceanGraph Articlesのお問い合わせ）

問い合わせフォームから送信された情報は、お問い合わせへの回答および支援の調整に利用します。協力企業への情報共有に同意いただいた場合は、対応に必要な範囲で、お問い合わせ内容および連絡先を対応可能な協力企業へ共有することがあります。

第5条（外部サービスおよび第三者提供）

当方は、本サービスの提供に必要な範囲で、外部事業者へ情報の取扱いを委託することがあります。

当方は、法令上認められる場合を除き、ユーザー本人の同意なく個人情報を第三者へ提供しません。

第6条（安全管理）

当方は、取得した情報の漏えい、滅失、改ざん、不正アクセス等を防止するため、合理的な安全管理措置を講じます。

第7条（お問い合わせ）

本ポリシーまたはユーザー情報の取扱いに関するお問い合わせは、お問い合わせ窓口からご連絡ください。

第8条（プライバシーポリシーの変更）

当方は、法令、サービス内容または情報の取扱いの変更に応じて、本ポリシーを改定することがあります。重要な変更を行う場合は、本サービス上その他の適切な方法でお知らせします。

Contact information

For bug reports, feature requests, and general product feedback, signed-in users with a verified email address can use the OceanGraph feedback form.

For account, security, privacy, or other inquiries, contact us at the address below.

support@oceangraph.io