MODIS MOD09GA/GQ daily surface reflectance (250-500 m)

NASA LP DAAC

Specification

Code: AL16
Reliability: B Usable
Variables delivered: FAI, NDVI-on-water, floating-bloom detection over LARGE water bodies only
Resolution: 250 m (b1,b2) / 500 m
Cadence: DAILY
Coverage: 2000-02-24 → present
Cost: FREE
Login required: No (GEE)
Latency: ~1-3 days
CSV direct?: Via GEE → .csv
Sensor: MODIS Terra — 250 m, 1 day revisit

Chakaria HDSS PARTIAL Rural COASTAL

MEDIUM — can see the Matamuhuri estuary mouth and nearshore plume

Matlab HDSS YES Rural riverine

USEFUL — the Meghna is wide enough for 250 m, giving you a DAILY 2000-2026 bloom record

Dhaka City NOT APPLICABLE Urban inland

NOT APPLICABLE — every Dhaka water body is sub-250 m

Route: GEE
Endpoint / asset ID: MODIS/061/MOD09GA · MOD09GQ
Pipeline step: 3 Extract
Documentation: https://developers.google.com/earth-engine/datasets/catalog/MODIS_061_MOD09GA

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

VALIDATION STATUS

Well validated for land · water use is non-standard

KNOWN LIMITATION

Land-optimised atmospheric correction. Mixed land/water pixels dominate at the banks — erode the water mask by 2 pixels before extracting.