Network panel

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.

6. Derived / uncalibrated

AL19 · GEE Sen2Cor L2A NDCI → chlorophyll polynomial

(your own pipeline)

C Caution FREE NO ACCOUNT

Source · duration · capture cadence

Data source: (your own pipeline)
Access route: GEE
Endpoint / asset: computed in 06_algae_gee_3sites.py
Duration: 2017-03 → present
Capture cadence: 5 days
Resolution: 10-20 m
Delivers: Uncalibrated chlorophyll-a estimate in mg/m3
Command: 10_algae_daily_3sites.py --sensors s2

Why it is used for cholera. NOT VALIDATED for Bangladesh

Why not — catalogue limitation. The Mishra & Mishra polynomial was fitted on CHESAPEAKE BAY. Treat the output as an ORDINAL INDEX, not mg/m3, until you calibrate locally. Two ways to fix: (1) get Sarker et al. 2019 coefficients, (2) collect in-situ chlorophyll.

Site applicability

Site	Verdict	Why
Chakaria HDSS	YES	SCREENING ONLY
Matlab HDSS	YES	SCREENING ONLY
Dhaka City	YES	SCREENING ONLY

Reliable · accessible · authentic

C Caution

Reliability tier

OPEN

Accessible

(your own pipeline)

Authentic — operator

Documentation: https://doi.org/10.1016/j.rse.2011.10.016

Typed limitations (1)

CRITICAL Sen2Cor is land-optimised and fails over dark turbid water algorithmic

GEE's Sentinel-2 L2A uses Sen2Cor, which was designed for land surfaces. Over dark eutrophic water it frequently returns NEGATIVE reflectance, which propagates into any index built from it.

What to do: For anything you intend to publish as a concentration, download L1C from the Copernicus Data Space and run ACOLITE Dark Spectrum Fitting - dataset AL18. Alternatively calibrate locally against in-situ chlorophyll, or use the Bangladeshi coefficients in Sarker et al. 2019.