Trees

Canopy health, from orbit.

The same Sentinel-2 satellite that watches the lakes reads the greenness of HRM's big tree canopies. Each park's NDVI over the last 45 days is compared with the same weeks in the two previous summers. A canopy that is much less green than its own past is a stress signal worth a site visit.

Parks watched

Flagged below usual

Latest clear look

Fetched

How it is computed

NDVI now against the park's own past

Sentinel-2 L2A at 20 m, bands B04 and B08, NDVI = (B08 − B04) / (B08 + B04), averaged over pixels the scene classifier marks as vegetation, so water, roads and buildings inside each rectangle drop out. One value per clear day.

What it cannot do: see individual trees, tell drought from disease from early leaf-off, or replace an arborist. A drop is a reason to look, not a diagnosis. Clouds hide the ground; the card shows how many clear looks the number rests on. Contains modified Copernicus Sentinel data 2024 to 2026.