SAR

easysnowdata.sar

Synthetic aperture radar (active microwave) products.

Pairs with easysnowdata.optical (passive optical). Backscatter processing — dB conversion, border noise, terrain geometry, and the local incidence angle — lives in easysnowdata.processing.sar.

easysnowdata.sar.sentinel1

Sentinel-1 radiometrically terrain-corrected (RTC) backscatter.

Sources (companion file §B.1):

planetary-computer (default)

sentinel-1-rtc: 10 m gamma0 from 2014-10, credential-free, scene based. No incidence-angle layer.

opera-rtc-s1

OPERA RTC-S1 on ASF via CMR-STAC cloudstac/ASF: 30 m, burst based, 2016-04 onward, one single-band COG per polarization plus a layover and shadow mask. Earthdata Login. Its companion static product carries the local incidence angle.

gee

OPERA/RTC/L2_V1/S1 re-served by Earth Engine, without the static layers.

Local incidence angle has its own three routes, and the credential-free one is a computation rather than a download. The angle belongs to one acquisition geometry, so the routes never fuse tracks: without relative_orbit= the result carries a relative_orbit dimension with one raster per track that crosses the AOI:

import easysnowdata as esd
s1_ds = esd.sar.sentinel1.load(aoi, "2023-10/2024-06", units="dB")
lia_ds = esd.sar.sentinel1.local_incidence_angle(aoi)  # every track
lia_ds = esd.sar.sentinel1.local_incidence_angle(aoi, relative_orbit=137)  # one
lia_ds = esd.sar.sentinel1.local_incidence_angle(aoi, source="dem")  # no account

search	Search a Sentinel-1 RTC catalog and return the items as a GeoDataFrame.
load	Load Sentinel-1 RTC backscatter as a lazy xarray.Dataset.
local_incidence_angle	Local incidence angle (and, where available, the layover/shadow mask).
scene_geometry	The geometry of one track over aoi: track_geometries() reduced to the requested relative_orbit, or else the track with the most scenes.
track_geometries	The acquisition geometry of every Sentinel-1 track over aoi, by track.
incidence_angle_field	Ellipsoidal incidence angle across the swath, on the DEM's grid.