OPERA_L3_DIST-ALERT-HLS_PROVISIONAL_V0 v000

OPERA Land Surface Disturbance Alert from Harmonized Landsat Sentinel-2 provisional product (Version 0)


PI: Observational Products for End-Users from Remote Sensing Analysis (OPERA), Development Organization: University of Maryland (UMD) – Dr. Matt Hansen

Description

The 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 for a more detailed description of the individual layers provided in the DIST-ALERT product.

read more

Characteristics

Product Maturity

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.

Collection and Granule

Collection

Characteristic Description
CollectionSNWG OPERA Disturbance
DOI10.5067/SNWG/OPERA_L3_DIST-ALERT-HLS_PROVISIONAL_V0.000
File Size~7 MB
Temporal ResolutionMulti-Day
Temporal Extent2022-01-01 to Present
Spatial ExtentGlobal (Non-Antarctic)
Coordinate SystemUniversal Transverse Mercator (UTM)
DatumWorld Geodetic System (WGS84)
File FormatGeoTIFF
Geographic Dimensions109.8 km x 109.8 km

Granule

Characteristic Description
Number of Science Dataset (SDS) Layers19
Columns/Rows3660 x 3660
Pixel Size30 m

Layers / Variables

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

Indication of Vegetation Disturbance / Generic Spectral Difference

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 Product Specification.

Known Issues

Additional usage constraints are provided under Section 5 of the Algorithm Theoretical Basis Document (ATBD).


About the image

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 image

Documentation

Product Specification Document (PSD)
Algorithm Theoretical Basis Document (ATBD)

Using the Data

Access Data

Citation

DOI: 10.5067/SNWG/OPERA_L3_DIST-ALERT-HLS_PROVISIONAL_V0.000