Mapping Kolkata's AQI from Orbit — Finding the Hotspots Ground Monitors Miss
Kolkata's official Kolkata AQI rests on a handful of CPCB ground stations clustered around Victoria, Rabindra Sarobar, and Ballygunge. AURA fuses Sentinel-5P TROPOMI columnar NO₂ and HCHO with INSAT-3D AOD and a CNN-LSTM surface-AQI model to deliver a 1 km2 Kolkata air quality grid every six hours — including the unmonitored neighborhoods responsible for most of the city's PM2.5 spikes.
The 100 km Blindspot
CPCB operates roughly seven continuous ambient air quality monitoring stations across the Kolkata Metropolitan Area — a city of more than 14 million people stretched across 1,886 km2. That leaves vast tracts of Howrah, Bidhannagar, Rajarhat, Maheshtala, and the industrial belt along the Hooghly with no real-time Kolkata AQI reading at all. Residents searching "Kolkata AQI today" for their own neighborhood see a citywide average that smooths over the very PM2.5 plumes they breathe.
AURA closes that gap. By regridding TROPOMI's 5.5 × 3.5 km tropospheric NO₂ and HCHO retrievals onto a 1 km2 mesh and conditioning on INSAT-3D aerosol optical depth, surface meteorology, and historical CPCB anchors, the platform produces a Kolkata air quality map that resolves street-grid pollution gradients an order of magnitude finer than the official network.
Back-Test: AURA vs CPCB, Jan–Jun 2025
We held out six months of hourly CPCB readings from the Victoria, Ballygunge, Jadavpur, and Rabindra Bharati stations and asked the AURA CNN-LSTM to predict surface PM2.5 from satellite inputs alone. Mean absolute error landed at ±12 AQI points across the validation window — comfortably within the ±20 envelope CPCB itself reports across stations on high-pollution winter days.
- Winter peak (Nov–Feb): AURA matched CPCB Severe-category days with 91% recall, including the Nov 14 stubble-burning plume.
- HCHO hotspots: DBSCAN clustering on TROPOMI HCHO flagged three previously uncharacterized industrial signatures along the Hooghly between Budge Budge and Garden Reach.
- Unmonitored wards: 38% of city wards received their first-ever sub-daily AQI estimate from AURA during the test window.
Why this matters for Kolkata
The same architecture that resolves Kolkata's air quality at neighborhood granularity scales across every Indian city — Delhi NCR, Mumbai, Chennai, Hyderabad, Bengaluru. But Kolkata is the proof point: a megacity where the gap between official Kolkata AQI numbers and lived experience is widest, and where satellite fusion delivers the most measurable public-health upside today.
For municipal authorities, that means actionable Kolkata pollution intelligence — ward-level dispatch, source attribution down to specific industrial sites, and multilingual alerts (Bengali, Hindi, English) that reach residents before exposure, not after.
See the full architecture
The 50-slide AURA pitch deck walks through the satellite ingestion pipeline, CNN-LSTM model, DBSCAN HCHO clustering, and the 4-tier authority dispatch system end-to-end.
Open the AURA Deck →