Download SWOT from AVISO

This notebook demonstrates how to browse and download SWOT LR data available on AVISO using the Altimetry Downloader Aviso tool.

Note

Required environment to run this notebook:

altimetry_downloader_aviso: see documentation.

Tutorial Objectives

Explore products from AVISO using the altimetry_downloader_aviso
Download a product using the altimetry_downloader_aviso
Load a dataset through Opendap

Import + code

import logging
logging.basicConfig(level=logging.INFO)

from pathlib import Path
import altimetry_downloader_aviso as dl_aviso

Parameters

Define an output folder to save results

output_dir= Path.home() / "TMP_DATA"

Using the Altimetry Downloader Aviso

Discover Aviso’s products

Use the summary and details commands to discover Aviso’s catalog products.

cat = dl_aviso.summary()

INFO:altimetry_downloader_aviso.catalog_client.client:Fetching products from Aviso's catalog...

for product in cat.products:
    print(f"{product.short_name} -> {product.title}")

SWOT_L3_LR_WIND_WAVE_Extended -> Wind & Wave product SWOT Level-3 WindWave - Extended
L4_exp_with_SWOT -> Experimental Products: Multimission Gridded (with SWOT) Level-4 Sea Surface Heights and Velocities
SWOT_L3_LR_WIND_WAVE_Light -> Wind & Wave product SWOT Level-3 WindWave - Light
SWOT_L3_LR_SSH_Unsmoothed -> Altimetry product SWOT Level-3 Low Rate SSH - Unsmoothed
SWOT_L3_LR_SSH_Technical -> Altimetry product SWOT Level-3 Low Rate SSH - Technical
SWOT_L2_LR_SSH_Expert -> Altimetry product SWOT Level-2 KaRIn Low Rate SSH - Expert
SWOT_L3_LR_SSH_Expert -> Altimetry product SWOT Level-3 Low Rate SSH - Expert
SWOT_L2_LR_SSH_Basic -> Altimetry product SWOT Level-2 KaRIn Low Rate SSH - Basic
SWOT_L2_LR_SSH_WindWave -> Altimetry product SWOT Level-2 KaRIn Low Rate SSH - WindWave
SWOT_L2_LR_SSH_Unsmoothed -> Altimetry product SWOT Level-2 KaRIn Low Rate SSH - Unsmoothed
SWOT_L3_LR_SSH_Basic -> Altimetry product SWOT Level-3 Low Rate SSH - Basic

product = dl_aviso.details('SWOT_L3_LR_SSH_Basic')

INFO:altimetry_downloader_aviso.catalog_client.client:Fetching products from Aviso's catalog...
INFO:altimetry_downloader_aviso.catalog_client.client:Requesting 'SWOT_L3_LR_SSH_Basic' product from Aviso's catalog...

product.last_version

'v3.0'

Tip

In order to explore data on AVISO’s catalog (see half-orbits available…), you can explore the catalog url with the product’s tds_catalog_url attribute

product.tds_catalog_url

'https://tds-odatis.aviso.altimetry.fr/thredds/catalog/L3/SWOT_KARIN-L3_LR_SSH.html'

Download a product

Use the get command to download a product from Aviso.

The first time you download a product using the Altimetry Downloader Aviso, credentials will be asked for Aviso authentication. They will be stored in a ~/.netrc file.

Aviso authentication screenshot

dl_aviso.get?

Signature:
dl_aviso.get(
    product_short_name: str,
    output_dir: str | pathlib.Path,
    cycle_number: int | list[int] | None = None,
    pass_number: int | list[int] | None = None,
    time: tuple[numpy.datetime64, numpy.datetime64] | None = None,
    version: str | None = None,
    overwrite: bool = False,
) -> list[str]
Docstring:
Downloads a product from Aviso's Thredds Data Server.

Parameters
----------
product_short_name
    the short name of the product
output_dir
    directory to store downloaded product files
cycle_number
    the cycle number for files/folders selection
pass_number
    the pass number for files/folders selection
time
    the period for files/folders selection
version
    the version for files/folders selection
overwrite: bool
    whether to overwrite files if they already exist

Returns
-------
    The list of downloaded local file paths
File:      ~/workspace/GITHUB_robin-cls/aviso_robin-cls/altimetry_downloader_aviso/core.py
Type:      function

dl_aviso.get(
    'SWOT_L2_LR_SSH_Basic', 
    output_dir=output_dir, 
    cycle_number=37, 
    pass_number=2,
    version='PID0'
)

INFO:altimetry_downloader_aviso.catalog_client.client:Fetching products from Aviso's catalog...
INFO:altimetry_downloader_aviso.catalog_client.granule_discoverer:Filtering SWOT_L2_LR_SSH_Basic product with filters {'cycle_number': 37, 'pass_number': 2, 'version': 'PID0'}...
INFO:altimetry_downloader_aviso.core:1 files to download. 0 files already exist.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L2_LR_SSH_Basic_037_002_20250810T092805_20250810T101933_PID0_01.nc downloaded.

['/home/atonneau/TMP_DATA/SWOT_L2_LR_SSH_Basic_037_002_20250810T092805_20250810T101933_PID0_01.nc']

To download several cycles and/or half-orbits:

dl_aviso.get(
    'SWOT_L3_LR_SSH_Basic', 
    output_dir=output_dir, 
    cycle_number=[40, 41], 
    pass_number=list(range(10, 16)),
    overwrite=True
)

INFO:altimetry_downloader_aviso.catalog_client.client:Fetching products from Aviso's catalog...
INFO:altimetry_downloader_aviso.catalog_client.granule_discoverer:Filtering SWOT_L3_LR_SSH_Basic product with filters {'cycle_number': [40, 41], 'pass_number': [10, 11, 12, 13, 14, 15]}...
INFO:altimetry_downloader_aviso.core:12 files to download.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_010_20251012T063453_20251012T072620_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_011_20251012T072620_20251012T081747_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_012_20251012T081747_20251012T090913_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_013_20251012T090914_20251012T100040_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_014_20251012T100041_20251012T105207_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_015_20251012T105207_20251012T114334_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_010_20251102T031959_20251102T041126_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_011_20251102T041126_20251102T050253_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_012_20251102T050253_20251102T055419_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_013_20251102T055420_20251102T064546_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_014_20251102T064547_20251102T073713_v3.0.nc downloaded.
INFO:altimetry_downloader_aviso.tds_client:File /home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_015_20251102T073714_20251102T082840_v3.0.nc downloaded.

['/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_010_20251012T063453_20251012T072620_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_011_20251012T072620_20251012T081747_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_012_20251012T081747_20251012T090913_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_013_20251012T090914_20251012T100040_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_014_20251012T100041_20251012T105207_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_040_015_20251012T105207_20251012T114334_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_010_20251102T031959_20251102T041126_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_011_20251102T041126_20251102T050253_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_012_20251102T050253_20251102T055419_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_013_20251102T055420_20251102T064546_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_014_20251102T064547_20251102T073713_v3.0.nc',
 '/home/atonneau/TMP_DATA/SWOT_L3_LR_SSH_Basic_041_015_20251102T073714_20251102T082840_v3.0.nc']

Load a dataset via OPeNDAP

To find the data you want to load, you can explore the Swot LR L2 or Swot LR L3 catalogues.

Copy the OPeNDAP URL to load the dataset through OPeNDAP:

OPeNDAP screenshot

Note

Environment needed to run the following:

xarray
requests
altimetry_downloader_aviso

import warnings
warnings.filterwarnings('ignore')

import requests as rq
import xarray as xr
from xarray.backends import PydapDataStore

NETRC_PATH = Path.home() / '.netrc'

def open_dataset(dataset_url):
    """ Open the dataset at dataset_url.
    Args:
        dataset_url

    Returns:
        xr.Dataset
    """            
    session = rq.Session()
    try:
        store = PydapDataStore.open(dataset_url, session=session, timeout=300, user_charset='UTF-8')
        return xr.open_dataset(store)
    except Exception as e:
        print(f"Something wrong with opendap url {dataset_url}: {e}")

swot_lr_dataset_url = "https://tds-odatis.aviso.altimetry.fr/thredds/dodsC/dataset-l3-swot-karin-nadir-validated/l3_lr_ssh/v3_0/Basic/forward/cycle_037/SWOT_L3_LR_SSH_Basic_037_014_20250810T194528_20250810T203655_v3.0.nc"

Store the dataset to a NetCDF file

nc_file= output_dir / "my_swot_data.nc"

# Set encoding for each variable
for var in list(ds.keys()):
    ds[var].encoding = {'zlib':True, 'complevel':5}

ds.to_netcdf(nc_file, mode='w')

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