Sentinel-2 MSI Level-2A (harmonised)

ESA Copernicus

Specification

Code: AL03
Reliability: A+ Gold
Variables delivered: NDCI, MCI, FAI, phycocyanin proxy, turbidity, MNDWI water mask, bloom area
Resolution: 10 m (B2,3,4,8) / 20 m (B5 red-edge 705 nm)
Cadence: 5 days (2-3 d with S2C from 2025)
Coverage: 2015-06 (L1C) / 2017-03 (L2A) → present
Cost: FREE
Login required: No (GEE) / free registration (CDSE)
Latency: ~1-3 days
CSV direct?: Via GEE reduceRegion → .csv export
Sensor: Sentinel-2 MSI — 20 m, 5 day revisit

Applicability by site

Chakaria HDSS YES Rural COASTAL

HIGHEST VALUE — resolves individual shrimp ponds in the Chakaria Sundarbans

Matlab HDSS YES Rural riverine

HIGHEST VALUE — resolves individual village ponds and the Dhonagoda

Dhaka City YES Urban inland

HIGHEST VALUE — the ONLY sensor that sees Hatirjheel, Gulshan Lake and the Buriganga

Access

Route: GEE · CDSE OData API · AWS/CDSE S3
Endpoint / asset ID: COPERNICUS/S2_SR_HARMONIZED | catalogue.dataspace.copernicus.eu/odata/v1/Products
Pipeline step: 3 Extract
Documentation: https://developers.google.com/earth-engine/datasets/catalog/COPERNICUS_S2_SR_HARMONIZED

Command

cd 01_Scripts
python 10_algae_daily_3sites.py --sensors s2

What to watch for

VALIDATION STATUS

Red-edge NDCI validated worldwide · Sen2Cor L2A over water is NOT validated

KNOWN 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.

Other datasets from the same sensor

AL18 · Sentinel-2 Level-1C + ACOLITE Dark Spectrum … AL19 · GEE Sen2Cor L2A NDCI → chlorophyll polynomial