20260408 10133500 1.0 TRUE 150000000 5000 ItemDescription (EXERCISE - DaNCE March 2026) Normalized Difference Water Index (NDWI) from PACE OCI for the Brazil Flood May 2024. <div style='text-align:Left;'><div><div>Dates of Images:Dates: 04/20/2024 (pre-flood), 05/06/2024, 05/07/2024, 05/09/2024, 05/15/2024, 05/21/2024 Time Zone: GMT (local crossing time of ~1:00 pm)Summary:These are NDWI measurements from PACE OCI using surface reflectances from OCI's SFREFL suite of the 2024 flooding in Brazil. NDWI is a normalized band ratio using the green (555 nm) and NIR (860 nm) for water content detection (green - nir / green + nir). The images show how the flood developed from a pre-flood day (04/20/2024) to the proceeding flooded days (through 05/21/2024) at ~1:00 local time (the overpass of the instrument). The changing extent of the floodwaters, along with what looks to be the amount of suspended sediment, is especially clear against the background of vegetation. Users should take into account that these floodwaters were sediment-laden, and thus some of that signal may depress the water signal. However, the change in NDWI from the pre-flood day can be used to identify flood extent.Suggested Use:NDWI is a normalized band ratio measuring the presence of water. Higher positive values water surfaces, low positive values to ~0 indicates flooding or high humidity, and negative values mean non-aqueous or drought conditions. In these images, it is clear that the presence of water increases greatly around the Jacui River during flood days compared to the pre-flood day (04/20/2024), showing the transition of the area around the Jacui River from non-flooded conditions (low NDWI values) to flooded (higher NDWI). Clouds have been screened from these products.Satellite/Sensor/Resolution:Satellite: PACE, sensor: OCITemporal resolution: dailySpatial resolution: gridded to 0.015 degrees from a Level 2 product in instrument swath (varying pixel size, 1.2 km at nadir).Credits:NASA PACE Team, POC: Skye Caplan, Link to data: https://search.earthdata.nasa.gov/search/granules?p=C3620139902-OB_CLOUD&pg[0][v]=f&pg[0][gsk]=-start_date&q=oci%20sfrefl </div></div></div> NASA PACE Team, POC: Skye Caplan. ex2602_pace_ndwi NDWI Normalized Difference Water Index NDWI PACE Plankton Aerosol Cloud ocean Ecosystem PACE OCI Brazil NASA NASA Disasters <div style='text-align:Left;'>NASA data and products are freely available to federal, state, public, non-profit and commercial users. This information can be experimental- or research-grade data products and may not be appropriate for operational use. These NASA data products, services, and the Disasters Mapping Portal are intended to aid decision makers and enhance situational awareness, but these data are not guaranteed to be consistently available or routinely updated.</div> 20260408