News

AVISO is releasing a suite of open-source Python libraries for exploring, accessing, and handling satellite altimetry datasets.

These tools make it easier to explore, download (including spatio-temporal subsets, so you only download the data you need), and work with SWOT altimetry products. They are available with documentation on GitHub repositories, and can be installed via conda-forge.

Swot tracks over an area and a given day (during Typhoon Bavi - dots represent its strength and path). The tracks & cycle were found using Altimetry Search, downloaded using Altimetry Downloader Aviso.

1. Altimetry Downloader Aviso

Search and download SWOT altimetry products (CLI or Python) from the AVISO catalog, via HTTPS or OpenDAP subsetting.
CNES GitHub repository: https://cnes.github.io/altimetry-downloader-aviso/

from altimetry_downloader_aviso import get

local_files = get(
   "SWOT_L3_LR_SSH_Basic",
   output_dir="aviso_dir",
   cycle_number=7,
   pass_number=[12, 13],
)

2. Altimetry Search

Find SWOT mission passes by date and area (Python API or Binder GUI).
CNES GitHub repository: https://github.com/CNES/altimetry-search

import numpy
from altimetry.search import Mission, get_selected_passes

selected_passes = get_selected_passes(
   Mission.SWOT_SWATH_SCIENCE,
   date=numpy.datetime64("2024-01-01"),
)

3. Altimetry-io

Unified reading of NetCDF altimetry collections (SWOT L2/L3, Nadir L2/L3), independent of underlying file layout.
CNES GitHub repository: https://github.com/CNES/altimetry-io

from altimetry.io import AltimetryData, FileCollectionSource

alti_data = AltimetryData(
   source=FileCollectionSource(path="data_dir", ftype="SWOT_L3_LR_SSH", subset="Unsmoothed")
)
ds = alti_data.query_orbit(cycle_number=13, pass_number=[153, 155],
                          variables=["time", "latitude", "longitude", "ssha_unedited"])

4. FCollections

Core library for querying a file or dataset collections by filename and folder metadata. Used as a dependency by Altimetry-io.
CNES GitHub repository: https://cnes.github.io/fcollections/

from fcollections.implementations import NetcdfFilesDatabaseSwotLRL3

fc = NetcdfFilesDatabaseSwotLRL3("data")
fc.query(cycle_number=1, pass_number=1)

All four packages are open-source (BSD-3-Clause / Apache 2.0) and available on the SWOT-community GitHub repository: swot-community.github.io/SWOT-galleries/tools.html.