FORMA Alert Thresholds

AI-generated Key Takeaways

• WRI has stopped updating FORMA alerts to simplify Global Forest Watch and reduce redundancy, as Terra-i and GLAD were more frequently used and Terra-i outperformed FORMA globally.

• FORMA alerts were detected using a combination of MODIS NDVI and FIRMS products, with models developed for each ecogroup.

• The thresholds for a FORMA alert are equal to the maximum of 25% cleared or 40% of the historical maximum clearing for a pixel in its ecogroup.

• The delta_bound band indicates the percentage threshold at which a FORMA alert is produced, ranging from 25% to 40%.

• The FORMA datasets are available for use without restriction, requesting attribution to WRI and GFW.

Dataset Availability

2012-01-01T00:00:00Z–2016-01-01T00:00:00Z

Dataset Provider

World Resources Institute / Global Forest Watch

Earth Engine Snippet

ee.Image("WRI/GFW/FORMA/thresholds")

Tags

daily deforestation fire forest forma gfw modis monitoring wri

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.

This image contains the thresholds at which, when crossed, a FORMA alert is produced. The values are equal to max(25,40%*RegionalMax), where RegionalMax is the historical maximum clearing for a pixel in this ecogroup.

Bands

Pixel Size
250 meters

Bands

Name	Units	Min	Max	Pixel Size	Description
delta_bound	%	25	40	meters	The thresholds at which, when crossed, a FORMA alert is produced

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.

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Code Editor (JavaScript)

var dataset = ee.Image('WRI/GFW/FORMA/thresholds');
var thresholds = dataset.select('delta_bound');
var visParams = {
  min: 0,
  max: 50,
};
Map.setCenter(26, -8, 3);
Map.addLayer(thresholds, visParams, 'Thresholds for FORMA alerts');

Open in Code Editor

FORMA Alert Thresholds

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 …

WRI/GFW/FORMA/thresholds, daily,deforestation,fire,forest,forma,gfw,modis,monitoring,wri

2012-01-01T00:00:00Z/2016-01-01T00:00:00Z

-50 -120 40 180

Google Earth Engine

https://developers.google.com/earth-engine/datasets