Dates of Images:

Pre-Event: 9/14, 9/16, 9/19, 9/21

Post-Event: 9/26, 9/28

Date of Next Image:

Varies by region, typically 12 days since previous pass. Set time slider to most recent interval and click on area of interest to identify date of last pass.

Summary:

The Alaska Satellite Facility has developed false color Red, Green, Blue (RGB) and Radiometrically Terrain-Correct (RTC) composites and surface water extent products of the Sentinel-1A/B Synthetic Aperture Radar (SAR) instrument which assigns the co- and cross-polarization information to a channel in the composite. When used to support a flooding event, areas in blue denotes water present at the time of the satellite overpass before or after the start of the flooding event.

Sentinel-1 RGB Decomposition of RTC VV and VH imagery over United States coastlines. Blue areas have low returns in VV and VH (smooth surfaces such as calm water, but also frozen/crusted soil or dry sand), Green areas have high returns in VH (volume scatterers such as vegetation or some types of snow/ice), and Red areas have relatively high VV returns and relatively low VH returns (such as urban or sparsely vegetated areas).

Suggested Use:

In this image, water appears in blue, vegetated areas in shades of green and urban areas in bright orange. It is recommended to use this product with ancillary information to derive flooded areas.

Post-event data is classified from the above imagery shows water that is detected by the sensor with different colors indicating different land cover/land use classifications from CDL that appear to have water and are potentially flooded.

Blue (1): Known Water

Red (2): Flooded Developed

Green (3): Flooded Vegetation

Orange (4): Flooded Cropland/Grassland

Gray (5): Clouds/Cloud Shadow

(0): No Data

Satellite/Sensor:

Synthetic Aperture Radar on European Space Agency's (ESA) Copernicus Sentinel-1A/B satellite

NOTE: Sentinel-1B is no longer acquiring data and is only available into December 2021

Resolution:

20 meters

Esri REST Endpoint:

See URL on the right.

RGB Product:

https://gis.asf.alaska.edu/arcgis/rest/services/ASF_S1/ASF_S1_RGB/ImageServer

RTC Product:

VV - https://gis.asf.alaska.edu/arcgis/rest/services/ASF_S1/ASF_S1_RTC_VV/ImageServer

VH - https://gis.asf.alaska.edu/arcgis/rest/services/ASF_S1/ASF_S1_RTC_VH/ImageServer

Surface Water Extent Product:

https://gis.asf.alaska.edu/arcgis/rest/services/ASF_S1/ASF_S1_WM/ImageServer

WMS:

https://maps.disasters.nasa.gov/ags04/services/hurricane_helene_2024/sentinel1/MapServer/WMSServer

Data Download:

https://maps.disasters.nasa.gov/download/gis_products/event_specific/2024/hurricane_helene_202409/sentinel1/

Groups