Sentinel-1¶

Overview¶

Sentinel-1 is a C-band synthetic aperture radar (SAR) mission supporting Copernicus land and marine monitoring services. It provides all-weather, day-and-night radar imagery with a spatial resolution ranging from 5m to 40m and a revisit time of 6 to 12 days, depending on the location and acquisition mode.

In GeeFetch, Sentinel-1 data is accessed via the Google Earth Engine collection COPERNICUS/S1_GRD (Ground Range Detected).

Processing¶

Filtering by date range and area of interest
Filtering by orbit availability (see configuration options)
Mosaicking of overlapping acquisitions
Resampling to target resolution
Scaling to maximize precision within the requested data type. Pixels outside of the range \((-30, 0)\) saturate. For instance, if the requested datatype is uint8, the image is scaled by \(x \mapsto (x + 30) \cdot 255/30\).

Available Bands for download¶

Band	Description	Native resolution	Download by default
VV	Vertical transmit, vertical receive	10m	yes
VH	Vertical transmit, horizontal receive	10m	yes
HH	Horizontal transmit, horizontal receive	10m	no
HV	Horizontal transmit, vertical receive	10m	no

Refer to COPERNICUS/S1_GRD for more details.

Configuration Options¶

See common configuration options for non Sentinel-1-specific configuration. Additionnally, you may provide the following options.

Attributes:

Name	Type	Description
`orbit`	`S1Orbit`	Orbit direction to filter Sentinel-1 acquisitions. Can be ASCENDING, DESCENDING, BOTH, or AS_BANDS to download ascending and descending composites as separate bands. Defaults to BOTH.

Example Usage¶

Command Line¶

Write the following config.yaml

data_dir: ~/satellite_data
satellite_default:
  aoi:
    spatial:
      left: 2.2
      bottom: 48.7
      right: 2.5
      top: 49
      epsg: 4326
    temporal:
      start_date: "2023-06-01"
      end_date: "2023-06-30"
  gee:
    ee_project_id: "your-gee-id"
  tile_size: 2000
  resolution: 10
s1:
  orbit: ASCENDING

then download with

geefetch s1 -c config.yaml

Python API¶

Though this is not geefetch main intended use, you can bypass the configuration and directly download Sentinel-1 data with the geefetch.data.get.download_s1 function. For instance, the CLI command above is roughly equivalent to

import logging
from pathlib import Path

from geobbox import GeoBoundingBox

from geefetch.data.get import download_s1
from geefetch.utils.enums import S1Orbit
from geefetch.utils.gee import auth
from geefetch.utils.log import setup

setup(level=logging.INFO)

data_dir = Path("geefetch_data/")
data_dir.mkdir(exist_ok=True)

auth("your-gee-id")

download_s1(
    data_dir,
    bbox=GeoBoundingBox(2.2, 48.7, 2.5, 49),
    start_date="2023-06-01",
    end_date="2023-06-30",
    tile_shape=2000,
    orbit=S1Orbit.ASCENDING
)

See the API reference of geefetch.data.get.download_s1 for more details.

Relevant library code¶

S1
geefetch.data.get.download_s1