Vegetation disturbance status data from the OPERA Land Surface Disturbance Alert from Harmonized Landsat Sentinel-2 provisional product over Argentina, July 28, 2022.
View full-size imageThe Observational Products for End-Users from Remote Sensing Analysis (OPERA) Land Surface Disturbance Alert from Harmonized Landsat Sentinel-2 (HLS) provisional data product Version 0 maps vegetation disturbance alerts from data collected by Landsat 8 and Landsat 9 Operational Land Imager (OLI) and Sentinel-2A and Sentinel-2B Multi-Spectral Instrument (MSI). Vegetation disturbance alert is detected at 30 meter (m) spatial resolution when there is an indicated decrease in vegetation cover within an HLS pixel. The product also provides auxiliary generic disturbance information as determined from the variations of the reflectance through the HLS scenes to provide information about more general disturbance trends. HLS data represent the highest temporal frequency data available at medium spatial resolution. The combined observations will provide greater sensitivity to land changes, whether of large magnitude/short duration, or small magnitude/long duration.
The OPERA_L3_DIST-ALERT-HLS (or DIST-ALERT) data product is provided in Cloud Optimized GeoTIFF (COG) format, and each layer is distributed as a separate file. There are 19 layers contained within in the DIST-ALERT product: vegetation disturbance status, current vegetation cover indicator, current vegetation anomaly value, historical vegetation cover indicator, max vegetation anomaly value, vegetation disturbance confidence layer, date of initial vegetation disturbance, number of detected vegetation loss anomalies, and vegetation disturbance duration. See the Product Specification Document (PSD) for a more detailed description of the individual layers provided in the DIST-ALERT product.
Provisional DIST-ALERT data have not been validated for their science quality and should not be used in science research or applications. If you are interested in exploring these provisional datasets, please download the data from NASA's Earthdata Search. If you have any feedback or questions, please contact LP DAAC.
| Characteristic | Description |
|---|---|
| Collection | SNWG OPERA Disturbance |
| DOI | 10.5067/SNWG/OPERA_L3_DIST-ALERT-HLS_PROVISIONAL_V0.000 |
| File Size | ~7 MB |
| Temporal Resolution | Multi-Day |
| Temporal Extent | 2022-01-01 to Present |
| Spatial Extent | Global (Non-Antarctic) |
| Coordinate System | Universal Transverse Mercator (UTM) |
| Datum | World Geodetic System (WGS84) |
| File Format | GeoTIFF |
| Geographic Dimensions | 109.8 km x 109.8 km |
| Characteristic | Description |
|---|---|
| Number of Science Dataset (SDS) Layers | 19 |
| Columns/Rows | 3660 x 3660 |
| Pixel Size | 30 m |
| SDS Name | Description | Units | Data Type | Fill Value | No Data Value | Valid Range | Scale Factor |
|---|---|---|---|---|---|---|---|
| VEG-DIST-STATUS¹ | Vegetation disturbance status | Class Flag | 8-bit unsigned integer | N/A | 255 | 0 to 4 | N/A |
| VEG-IND | Vegetation percent | Percent | 8-bit unsigned integer | N/A | 255 | 0 to 100 | N/A |
| VEG-ANOM | Vegetation loss | Percent | 8-bit unsigned integer | N/A | 255 | 0 to 100 | N/A |
| VEG-HIST | Vegetation percent of baseline at the time of max anomaly | Percent | 8-bit unsigned integer | N/A | 255 | 0 to 100; 200=no disturbance | N/A |
| VEG-ANOM-MAX | Maximum vegetation loss anomaly | Percent | 8-bit unsigned integer | N/A | 255 | 0 to 100 | N/A |
| VEG-DIST-CONF² | Confidence of vegetation disturbance | N/A | 16-bit signed integer | N/A | -1 | 0=No disturbance; >0=disturbance confidence | N/A |
| VEG-DIST-DATE² | Day of vegetation disturbance | Day | 16-bit signed integer | N/A | -1 | 0=No vegetation anomalies in the last year; >0=Day of initial anomaly detection in the last year | N/A |
| VEG-DIST-COUNT² | Count of observations with vegetation loss | N/A | 8-bit unsigned integer | N/A | 255 | 0=No disturbance; 1 to 254=Count of loss anomalies | N/A |
| VEG-DIST-DUR² | Number of days of ongoing loss anomalies since initial detection | Day | 16-bit signed integer | N/A | -1 | 0=No disturbance; 1 to 366=Number of days from first anomaly to most recent anomaly detection | N/A |
| VEG-LAST-DATE² | Day of last land observation for vegetation disturbance detection | Day | 16-bit signed integer | N/A | -1 | ≥1=Last day assessed | N/A |
| GEN-DIST-STATUS¹ | Generic disturbance status | Class Flag | 8-bit unsigned integer | N/A | 255 | 0 to 4 | N/A |
| GEN-ANOM² | Spectral anomaly | N/A | 16-bit signed integer | N/A | -1 | 0=No disturbance; >0= Spectral distance | N/A |
| GEN-ANOM-MAX² | Maximum spectral anomaly | N/A | 16-bit signed integer | N/A | -1 | 0=No disturbance; >0= Spectral distance | N/A |
| GEN-DIST-CONF² | Confidence of generic disturbance | N/A | 16-bit signed integer | N/A | -1 | 0=No disturbance; >0=Disturbance confidence | N/A |
| GEN-DIST-DATE² | Day of generic disturbance | Day | 16-bit signed integer | N/A | -1 | 0=No spectral anomalies in the last year; >0=Day of initial anomaly detection in the last year | N/A |
| GEN-DIST-COUNT² | Count of observations with spectral anomaly | N/A | 8-bit unsigned integer | N/A | 255 | 0=No disturbance; 1 to 254=Count of loss anomalies | N/A |
| GEN-DIST-DUR² | Number of days of ongoing spectral anomalies since initial detection | Day | 16-bit signed integer | N/A | -1 | 0=No disturbance; 1 to 366=Number of days from first anomaly to most recent anomaly detection | N/A |
| GEN-LAST-DATE² | Day of last land observation for generic disturbance detection | Day | 16-bit signed integer | N/A | -1 | ≥1=Last day assessed | N/A |
| LAND-MASK | LAND MASK | N/A | 8-bit unsigned integer | N/A | N/A | 0=Not land; 1=Land | N/A |
| Value | Description |
|---|---|
| 0 | No disturbance |
| 1 | Provisional <50% |
| 2 | Confirmed <50% |
| 3 | Provisional ≥50% |
| 4 | Confirmed ≥50% |
| 255 | No data |
¹ “Provisional” is used from the first detection until vegetation disturbance/generic spectral differences are detected for a consecutive number of HLS scenes, when it is then labeled “confirmed”. If a “provisional” disturbance does not have repeated detections, it is removed. These labels are reported for both above and below the 50% disturbance threshold.
² For more information about raster layers see Table 4-1 in the PSD.
Additional usage constraints are provided under Section 5 of the Algorithm Theoretical Basis Document (ATBD).