New Ifremer STAC backend for ArgoIndex

[gmaze]

STAC stands for SpatioTemporal Asset Catalogs

The STAC specification is a common language to describe geospatial information, so it can more easily be worked with, indexed, and discovered.

Ifremer is implementing a STAC catalog for Argo floats and profiles: https://stac-browser.ifremer.fr/

It would be "very" FAIR to provide such a STAC backend for the argopy ArgoIndex class.

In practice, this would means that the ArgoIndex will rely on STAC http requests, rather than index file.

The strong added value of this feature would be an ArgoIndex that would not need to load an index file in memory.

But it remains to be determined how this could fit with the current design of ArgoIndex, which has already 2 backends to handle index csv content, as Pandas Dataframe or Pyarrow Tables.

It could go like this:

from argopy import ArgoIndex
idx = ArgoIndex(host='stac')

Also I don't know yet:

• how to search the catalog of floats or profiles (from the api called by the stac-browser),
• if this would necessarily need the pystac library (see also xpystac).

poke @tcarval

[erwanbodere]

Two STAC collections :

• https://stac-pg-api.ifremer.fr/collections/argo_platforms/
• https://stac-pg-api.ifremer.fr/collections/argo_profiles/

Query example : https://stac-pg-api.ifremer.fr/collections/argo_profiles/items?datetime=2025-11-13T00:00:00.000Z/2025-12-17T00:00:00.000Z&bbox=-14.23828125,34.88593094075317,2.9882812500000004,56.75272287205736&limit=1

You can use request or https://pypi.org/project/httpx/ if you want to skip pystac client and avoid to add new libraries (not tested)

Some example generated by LLM :

import requests

url = "https://stac-pg-api.ifremer.fr/collections/argo_profiles/items"
params = {
    "datetime": "2025-11-13T00:00:00.000Z/2025-12-17T00:00:00.000Z",
    "bbox": "-14.23828125,34.88593094075317,2.9882812500000004,56.75272287205736",
    "limit": 1,
}

response = requests.get(url, params=params)
response.raise_for_status()  # lève une erreur si HTTP != 200

data = response.json()

print("Nombre d'items retournés :", len(data.get("features", [])))

# Exemple : afficher l’ID du premier item
if data.get("features"):
    item = data["features"][0]
    print("ID de l'item :", item["id"])
    print("Date :", item["properties"].get("datetime"))

or with HTTPX

import httpx
import asyncio

async def fetch_stac():
    url = "https://stac-pg-api.ifremer.fr/collections/argo_profiles/items"
    params = {
        "datetime": "2025-11-13T00:00:00.000Z/2025-12-17T00:00:00.000Z",
        "bbox": "-14.23828125,34.88593094075317,2.9882812500000004,56.75272287205736",
        "limit": 1,
    }

    async with httpx.AsyncClient() as client:
        response = await client.get(url, params=params)
        response.raise_for_status()

    data = response.json()
    return data

data = asyncio.run(fetch_stac())
print(data)