I have been trying to find either HH+HV data as EW or IW scans of Denmark in GRD or SLC products,
I am able to download multiple instances for 2016, but nothing seems to be present for 2017, request it from https://scihub.copernicus.eu/dhus.
I am using the SentinelAPI from sentinelsat in python, so I am unsure if this is the expected response or if there is some other way to get HH+HV data for 2017?
I also checked online via https://scihub.copernicus.eu/dhus directly and was not able to find any scan covering major parts of Denmark. Is this also what we could expect normally, so one will only get VV+VH data ?
You can check the observation scenario here:
https://sentinel.esa.int/web/sentinel/missions/sentinel-1/observation-scenario
The polarisation-coverage is depicted in the lower figure, as you can see HH is reserved for polar areas only:
https://sentinel.esa.int/documents/247904/2797009/Sentinel-1-mode-polarisation-pass-map-full
…I think there were HH+HV data available in 2016 due to calibration activities over nearby Flevoland in Holland, but such data will not normally be available I’m afraid.
Sorry to dig this old topic out, but the question is related.
As we know, Sentinel-1 HH data is only regularly available for selected parts of this Earth.
Now I just found 7 Sentinel-1 IW acquisitons with HH + HV polarizations acquired over Southern Germany between January and March 2021, for example: S1B_IW_GRDH_1SDH_20210313T053409_20210313T053433_025992_0319CF_D39C
I had a look at the S1 Observation Scenarios and plans, but I could not find any reason why this was done. Is there some reference where this short phase of HH+HV data is explained or at least mentioned?
Maybe @peter.meadows or @mengdahl have an idea.
From ASF’s website - its a calibration site.
https://asf.alaska.edu/data-sets/sar-data-sets/sentinel-1/sentinel-1-observation-plans/
Calibration and validation activities:
Aiming at the best achievable data quality of Sentinel-1 products, calibration and validation activities are routinely performed during the routine operations phase. These priority activities may locally and temporarily interfere with the delivery of coverage in consistent mode-polarization combination. Major regions affected by these activities are Northern Alpine Lowlands (Germany, Austria and Switzerland) and the narrow surroundings of Sao Paulo (Brazil), Houston and Chicago (USA). Limiting the consistency of static mode–polarization coverage and causing small observation gaps due to instrument switches, these activities bring the opportunity to explore the variety of the Sentinel-1 image modes to data users of the affected areas.
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As mentioned by @piyushrpt this HH/HV data is most likely acquired as part of the S1 routine calibration activity over the DLR calibration sites in southern Germany (location of their corner reflectors and transponders).
thank you both. If I wanted to refer to this calibration activities in a scientific publication, which document would you suggest?
For a recent summary of calibration activities I would suggest the ‘Sentinel-1 Annual Performance Report’ that is available from Sentinel 1 SAR Document Library - User Guides - Sentinel Online - Sentinel Online (copernicus.eu). The latest of these is from 2020. There are more regular Cyclic Reports but I think the annual report might be a better summary. Anyway talk a look and see what you think.
There might be recent conference papers but I’ve not been working on S1 for a couple of years now and so am not aware of the latest papers.
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To answer my own question - I case anyone is interested:
Here is an announcement: Copernicus Sentinel-1 calibration campaign on-going in Europe - Copernicus Sentinel-1 calibration campaign on-going in Europe - Sentinel Online