Colab notebooks for the Rutgers University Topics in Marine Science course. You'll learn Python by exploring real data from Redwing, a Slocum glider flying the Sentinel mission. Sentinel is a Rutgers / Teledyne Webb Research effort to fly the first autonomous underwater vehicle around the globe.
Everything here runs in Google Colab in your web browser. You don't need to install anything on your computer, and you don't need any coding experience to start.
- Sign in to a Google account (your Rutgers Google account works).
- Click an Open in Colab badge below.
- In Colab, go to File → Save a copy in Drive. That gives you your own copy to edit; changes to the original aren't saved.
- Run the cells from top to bottom: click ▶ next to a cell or press Shift + Enter.
| # | Notebook | What you'll do |
|---|---|---|
| 1 | Intro to Python and gliders |
Python crash course (math, variables, strings, lists, NumPy arrays), then download three days of Redwing data from ERDDAP with load_glider_data(), look at it with pandas, and make your first plots |
| 2 | Redwing engineering data |
How the glider flies: buoyancy engine, pitch, heading and fin (measured vs. commanded), vertical speed over the mission. Glider health: vacuum and battery. The ocean currents it fought. Ends with group exercises |
| 3 | Redwing science data |
What the CTD measured: whole-mission temperature/salinity/density sections, the Gulf Stream front, T–S diagrams and water masses, and dive vs. climb (sensor thermal lag). Ends with group exercises |
Do Activity 1 first. Activities 2 and 3 can be done in either order (or by different groups at the same time). All three use exactly the same load_glider_data() function.
A Slocum glider is a torpedo-shaped robot about 2 m long that flies through the ocean without a propeller. It pumps oil in and out of an external bladder to become heavier or lighter than seawater, and its wings turn that sinking and rising into forward motion. It flies a sawtooth ("yo") pattern, here down to ~1000 m and back. At the surface it gets a GPS fix and sends data home by satellite. A single glider can stay at sea for months.
Gliders record two kinds of data:
- Engineering (flight) data describe the vehicle: depth, pitch, roll, heading, buoyancy pump volume, battery position, battery charge, internal vacuum.
- Science data describe the ocean, mostly from the CTD (Conductivity–Temperature–Depth sensor). From conductivity, temperature, and pressure we calculate salinity and density.
Slocum variable names start with a prefix that tells you where they come from:
| Prefix | Meaning | Examples |
|---|---|---|
m_ |
measured by the flight computer | m_depth, m_pitch, m_battery, m_de_oil_vol |
c_ |
commanded: what the glider was told to do | c_heading, c_de_oil_vol |
sci_ |
measured by the science computer / sensors | sci_water_temp, sci_water_cond, sci_water_pressure |
x_ |
derived onboard | x_de_oil_flux |
Watch the units. Angles (m_pitch, m_heading) are in radians, sci_water_pressure is in bar (×10 for decibars ≈ metres), and sci_water_cond is in S/m (×10 for mS/cm, which is what gsw expects).
All three notebooks pull data live from the Rutgers glider ERDDAP server, so there are no files to download.
During a mission a glider only sends a small sample of its data home by satellite (real-time data). We use the delayed-mode data: the complete files stored on the glider, with every measurement (about one per second), processed after they were retrieved. Redwing has two delayed-mode datasets:
| Name in the code | Dataset ID | What's in it | Used in |
|---|---|---|---|
ENGINEERING_ID |
redwing-20251011T1511-trajectory-raw-delayed |
everything the glider logged: flight data plus raw CTD, Oct 2025 – May 2026 | Activities 1 and 2 |
SCIENCE_ID |
redwing-20251011T1511-profile-sci-delayed |
processed CTD profiles with salinity and density, Oct 2025 – Jan 2026 | Activity 3 |
The delayed-mode engineering files don't include the battery variables, so Activity 2 gets those from the real-time dataset, redwing-20251011T1511-trajectory-raw-rt.
Because the full-resolution data are millions of rows, the notebooks use ERDDAP server-side filters through load_glider_data(..., filters=[...]). For example, 'm_depth!=NaN' keeps only rows with a depth, and 'orderByMean("profile_id,pressure/5")' averages each profile into 5 dbar bins before sending it.
load_glider_data() works for any glider on that server. Give it a different dataset ID to try another one.
Colab already includes numpy, pandas, and matplotlib. The first code cell of each notebook installs the rest (this takes a few seconds):
| Package | What it's for |
|---|---|
erddapy |
Requesting data from ERDDAP servers |
cmocean |
Colormaps made for oceanography (thermal, haline, dense, ...) (Activities 2 and 3) |
gsw |
Seawater properties (density, conservative temperature) using TEOS-10 (Activity 3) |
| Problem | Fix |
|---|---|
NameError: name 'df' is not defined (or any variable) |
You skipped a cell. Run the cells above it, or use Runtime → Run before. |
ModuleNotFoundError: No module named 'erddapy' (or gsw, cmocean) |
Run the pip install cell at the top of the notebook. |
| Things are acting strangely | Runtime → Restart session and run all. |
HTTPError 502 / 503 from a data server |
The server is busy. Wait a minute and run the cell again. |
SSL CERTIFICATE_VERIFY_FAILED from the Rutgers ERDDAP server |
The notebooks handle this automatically. If you write your own code, copy the read_csv_from_url() function. |
| My edits disappeared | You were editing the original from GitHub. Use File → Save a copy in Drive first. |
- Pick any glider on the Rutgers ERDDAP server and run Activities 2 and 3 on it.
- Use Redwing's battery data to estimate how long a full-depth mission can last.
- Map where Redwing met the strongest currents and compare with the Gulf Stream's position.
- Measure CTD thermal lag by comparing dive and climb profiles. When does it matter most?
- Track the mixed layer deepening from fall into winter.
- Map how thick the Eighteen Degree Water layer was along the track.
- Compare real-time and delayed-mode data for the same day. What did the glider leave out?
- Compare Redwing's near-surface temperature with satellite sea surface temperature, for example NOAA's Blended SST, which is also on ERDDAP.
Activity_1_Intro_to_Python_and_Gliders.ipynb Python basics + first Redwing data
Activity_2_Redwing_Engineering.ipynb How Redwing flew, its health, and the currents it met
Activity_3_Redwing_Science.ipynb What Redwing's CTD measured in the ocean
README.md This guide
Older notebooks from the 2025 course (Sentinel test flights in Cape Cod Bay and off San Diego) are still in the git history.
Course materials by Joe Gradone, Rutgers University. Questions? Open an issue on this repository or ask in class.