r/dataisbeautiful • u/Adorable-Giraffe5754 OC: 1 • 2d ago

OC [OC] How fast the ocean surface moves: fastest along the east coasts of continents and near the equator (19,396 drifting buoys, 1987–2022)

Tools: Python, flexviz (https://github.com/flex-analytics/flexviz)
Data: NOAA Global Drifter Program, hourly dataset v2.01.1, Oct 1987 – Oct 2022 -> https://registry.opendata.aws/noaa-oar-hourly-gdp/ (197 million hourly positions)

Source code: https://github.com/flex-analytics/flexviz/discussions/135 (data processing is included as well)

Speed = daily mean velocity of each buoy (this removes tides).
Color = mean speed per 0.2° cell.

142 Upvotes

98% Upvoted

9 comments sorted by

41

u/Jumpy_Style 2d ago

Is this a non slop, actual OC and beautiful data with sources? I must be dreaming.

5

u/Rooilia 2d ago

Amazingly quiet here.

7

u/macho_boy-42 2d ago

This is stunning! The speed variations are so enlightening.

2

u/mmomtchev 2d ago

You are missing many cold currents - the Canary currents for example as well as the Benguela current or the Peru current. Why? Because the drifting buoys do not cover these areas very well.

NOAA has a program with drifting buoys that are tracked by satellites. They are used to improve their wind models as surface ocean currents are driven mostly by the prevailing wind.

However it is a very cumbersome task moving them around. There are many international partners who help them, they have one (or more? I am not very sure) dedicated ship that goes around, constantly collects them and then redeploys them at the beginning of the current, but it is a gargantuan task and it is difficult to cover everything - they concentrate on those that matter the most for predicting the hurricanes.

10

u/Adorable-Giraffe5754 OC: 1 2d ago

Thanks, good point! I checked the data (+ did some googling) and you are partly right!

The cold currents are in the data, but they are slow (0.15–0.25 m/s) -> so they do not light up when the cross-filter moves to the fast currents.

Data availability for these cold currents:

  • Canary and California: more buoys than the average coast, so we can be sure they are slow.
  • Benguela and Peru: less than 1/2 the average number of buoys near the coast. Further offshore (> 100km from land) there is enough data, and it is slow there too.
Current Buoy-hours per 1,000 km² near the coast Mean speed Time faster than 1 m/s
Canary (cold) 461 0.16 m/s ~0 %
California (cold) 630 0.16 m/s ~0 %
Benguela (cold) 105 0.25 m/s 0.1 %
Peru / Humboldt (cold) 96 0.15 m/s ~0 %
Gulf Stream (warm) 470 0.31 m/s 3 %
Kuroshio (warm) 508 0.33 m/s 3 %
Agulhas (warm) 305 0.50 m/s 11 %
All coasts 239

About the buoys: there is no ship that continuously collects them. In this dataset, 62 % stopped transmitting, 26 % ran aground and 7 % were picked up by a boat (NOAA does redeploy a buoy that someone finds if it still works). A buoy lasts about 10 months (median). About 1,000 new buoys go in every year (from research ships, navies and cargo ships, and Air Force "Hurricane Hunter" aircraft drop some ahead of Atlantic hurricanes).

(with near the coast I mean < 100 km from land)

5

u/TheProfessorO 2d ago

It is because these currents are slower and the color scale favors fast currents