Sentinel NDVI Data

[noamross]

• [ ] Identify sources, based on frequency/resolution/coverage tradeoffs and ease of download
• [ ] Create cached historical data download
• [ ] Integrate into training set
• [ ] Create live data download pipeline

[emmamendelsohn]

some initial notes, will continue to update

Sentinel-3 satellite User guide: https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-3-synergy Technical guide: https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-3-synergy

Sentinel-3 represents April 2014 to present. SOURCE FOR HISTORICAL NDVI NEEDED. Coverage for all of Africa.

There are two separate NDVI data products. Only the first (SY_2_VG1__ and SY_2_V10___) are available. The VGK product is used as an input for these products. Leaving these notes below because it took a while to understand the differences.

Sentinel-3 -> Synergy -> VGT-S -> NDVI (S1/S10)

• Packaging = Global

• Sampling = Spatial 1 km

• Frequency = Daily (S1), 10-day (S10)

• Latency = not specified

• Product type description = SY_2_VG1___ and SY_2_V10___ = 1 km VEGETATION-Like product 1 or 10 day synthesis surface reflectance and NDVI.

• Processing level description = A dedicated VGT-S software deals with the VGK product to compute daily and decade synthesis of surface reflectance, based on the maximum value of NDVI (to be consistent with the PROBA-V composite approach). It produces VG1 and V10 products.

• More description here.

  Sentinel-3 -> Synergy -> Level 2 -> VGK -> NDVI

• Packaging = Half orbit

• Sampling = 300 m

• Frequency = 1 dataset per half-orbit

• Latency = NTC (non-time critical)

• Product type description = SY_2_VGK___ = Surface reflectance over Land– used as input for VG-S product.

all Sentinel-3 data products (source)

Data Access There are two options for access: Copernicus Data Space Ecosystem and Copernicus Data Hub. The latter is being discontinued in June 2023. Copernicus Data Space has a browser and API. General documentation here; naming convention here.

Initial File Exploration For a single date, there are two files (can be explored manually via the browser interface). S3A = SENTINEL3A. S3B = SENTINEL3B. SENTINEL-3B's orbit is identical to SENTINEL-3A's orbit but flies +/-140° out of phase with SENTINEL-3A. Should we choose one or average both? S3A_SY_2_V10____20230301T000000_20230310T235959_20230312T231426_AFRICA____________PS1_O_NT_002.SEN3 S3B_SY_2_V10____20230301T000000_20230310T235959_20230313T143230_AFRICA____________PS2_O_NT_002.SEN3

To Discuss File storage for rasters

[emmamendelsohn]

Based on API guidance (https://documentation.dataspace.copernicus.eu/#/APIs/OData) and parameter guide (https://catalogue.dataspace.copernicus.eu/resto/api/collections/Sentinel3/describe.xml)

• [x] Acquire API token (note this is a refreshing token)
• [x] Query for filenames (based on hierarchies and naming conventions documented above). This should be a target.
• [x] Functionalize download

[emmamendelsohn]

We have the NDVI pipeline complete from the Sentinel satellite. We still need to get MODIS data.

[noamross]

Remind me why we're doing both?

[emmamendelsohn]

Sentinel goes back to 2018 only. MODIS I believe is expected to be discontinued soon.

[emmamendelsohn]

https://modis.gsfc.nasa.gov/data/

[emmamendelsohn]

closing this to reopen separate issue for MODIS data