- Dataset Availability
- 2012-01-01T00:00:00Z–2019-05-18T00:00:00Z
- Dataset Provider
- World Resources Institute / Global Forest Watch
- Earth Engine Snippet
-
ee.Image("WRI/GFW/FORMA/alerts") - Tags
Description
NOTE from WRI: WRI decided to stop updating FORMA alerts. The goal was to simplify the Global Forest Watch user experience and reduce redundancy. We found that Terra-i and GLAD were more frequently used. Moreover, using GLAD as a standard, found that Terra-i outperformed FORMA globally.
FORMA alerts are detected using a combination of two MODIS products: NDVI (Normalized Difference Vegetation Index) and FIRMS (Fires Information for Resource Management System). NDVI updates are processed every 16 days, while fire updates are processed daily. Models are developed individually for each ecogroup to relate the two inputs to the area of clearing, using the Hansen annual tree cover loss data to train the model. The minimum threshold to qualify as an alert is 25% of the pixel cleared, though thresholds vary by ecogroup to minimize false positives. Here is an example script for a quick introduction to the FORMA datasets.
The percentage of clearing takes a value of 0, no clearing detected, or in the range [ecogroup_bound:100), where ecogroup_bound is given by WRI/GFW/FORMA/thresholds . The time periods over which data is collected varies by N-days, where N is the number of days between the alert_date and the last MODIS NDVI update.
Bands
Resolution
250 meters
Bands
| Name | Units | Min | Max | Description |
|---|---|---|---|---|
alert_delta |
% | 0 | 100 | Percentage of clearing which during the 6 MODIS periods (96 + N days) preceding the corresponding alert_date value for the pixel |
alert_date |
ms | Timestamp in milliseconds since 1970/01/01 |
Terms of Use
Terms of Use
The FORMA datasets are available without restriction on use or distribution. WRI does request that the user give proper attribution and identify WRI and GFW, where applicable, as the source of the data.
Explore with Earth Engine
Code Editor (JavaScript)
var dataset = ee.Image('WRI/GFW/FORMA/alerts'); var formaAlerts = dataset.select('alert_delta'); var formaAlertsVis = { min: 25, max: 75, palette: ['d65898', 'da68a2'], }; Map.setCenter(6.746, 46.529, 6); Map.addLayer(formaAlerts, formaAlertsVis, 'FORMA Alerts');