SatHDSS
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Algae Dataset

Every data hub, dataset, sensor, variable, paper and limitation in one tree — and for each: where it comes from, how far back it goes, how often it captures, why it belongs in a cholera study, and why it does not work everywhere.

Highlight site All three Chakaria HDSS Matlab HDSS Dhaka City Choosing a site greys out everything that does not apply there.

2. Inland/coastal high-res

AL03 · Sentinel-2 MSI Level-2A (harmonised)
ESA Copernicus
A+ Gold FREE NO ACCOUNT

Source · duration · capture cadence

Data source
ESA Copernicus
Access route
GEE · CDSE OData API · AWS/CDSE S3
Endpoint / asset
COPERNICUS/S2_SR_HARMONIZED | catalogue.dataspace.copernicus.eu/odata/v1/Products
Duration
2015-06 (L1C) / 2017-03 (L2A) → present
Capture cadence
5 days (2-3 d with S2C from 2025)
Resolution
10 m (B2,3,4,8) / 20 m (B5 red-edge 705 nm)
Delivers
NDCI, MCI, FAI, phycocyanin proxy, turbidity, MNDWI water mask, bloom area
Command
10_algae_daily_3sites.py --sensors s2
Why it is used for cholera. Red-edge NDCI validated worldwide · Sen2Cor L2A over water is NOT validated
Why not — catalogue limitation. DOES NOT COVER 2000-2015. ~60-70% of Jun-Sep scenes lost to monsoon cloud. Sen2Cor is land-optimised and returns negative reflectance over dark turbid water — use ACOLITE on L1C for publication-grade values.

Site applicability

SiteVerdictWhy
Chakaria HDSS YES HIGHEST VALUE — resolves individual shrimp ponds in the Chakaria Sundarbans
Matlab HDSS YES HIGHEST VALUE — resolves individual village ponds and the Dhonagoda
Dhaka City YES HIGHEST VALUE — the ONLY sensor that sees Hatirjheel, Gulshan Lake and the Buriganga

Reliable · accessible · authentic

A+ Gold
Reliability tier
OPEN
Accessible
ESA Copernicus
Authentic — operator
Documentation: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR_HARMONIZED

Typed limitations (2)

CRITICAL Record starts mid-2015 - two-thirds of the study window is uncovered temporal

Sentinel-2 L1C begins June 2015 and L2A March 2017. The study period starts in 2000, so the single most capable inland sensor is absent for 15 of 26 years.

What to do: Landsat 30 m is the only backfill. Accept a 16-day cadence before 2015, bias-correct across the boundary, and consider modelling the pre-2015 era monthly.

HIGH No 620 nm band, so phycocyanin is a proxy only spectral

Sentinel-2 cannot measure the cyanobacteria-specific phycocyanin absorption feature. The B3/B5 ratio used as a stand-in responds to chlorophyll as well, so it cannot cleanly separate a harmful cyanobacterial bloom from a benign green-algal one.

What to do: At Chakaria and Matlab use Sentinel-3 OLCI band Oa07 for the true retrieval. At Dhaka - where cyanobacteria dominate - only the proxy exists. That is the main methodological risk in the study and it must be stated in the limitations section.
Full dataset page →