These data, collected from the Global Drifters Program, where used in the following publication:

State aggregations in Markov chains and block models of networks,
Faccin, Schaub and Delvenne, Phys. Rev. Lett., 127(7) p.078301 (2021)
ArXiv 2005.00337

The data reported here aggregate all drifters trajectiories up to June 2017 and are not kept updated.

The subdivision of the ocean is in square cells, each corresponding to a node. The Earth is divided into a grid of $100 \times 50$ cells with constant area.

Nodes or cells are reported in data/net-nmap.json.gz. The file contains a dictionary of nodes as follows:

{
    ...,
    "4999": [       // ID as string
        4999,       // ID as integer in [0: 5000)
        [
            49,     // x location in [0: 50)
            99      // y location in [0: 100)
        ],
        "ARCTIC OCEAN",  // a tag; do not trust it too much
        [
            78.52165904546642,   // latitude
            178.2                // longitude
        ]
    ],
    ...
}

Links between nodes are saved in:

data/net-t087.json.gz

It contains the drifter count that went from node 1 to node 2 in exactly 87 days. The list in coords holds node ID pairs while the list in data keeps the count of drifters that went from node 1 to node 2.

{
    "coords": [
        ...,
        [23, 77],
        ...,
    ],
    "data": [
        ...,
        13,
        ...
    ]
}