ex2602_pace_avw

Dates of Images: Pre-Event: 04/20/2024 (pre-flood) Post-Event: 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: This product is the apparent visible wavelength (AVW) of each pixel in a scene, approximating the overall color of the surface. It is calculated by taking the harmonic mean of surface reflectances from 350 nm to 895 nm, and can provide a sense of what has changed in the landscape by comparing several days against each other, as the change in apparent color of a surface often occurs under drastic circumstances. Dates covered include one pre-flood day (04/20/2024) and 5 flood days ending on 05/21/2024 at ~1:00 local time. AVW for each day is delivered, as is a % change from the pre-flood day to each of the 5 flood days afterward, showing the magnitude of color change in the area. Depending on the direction of change, one can infer the type of surface change from AVW. Typically, this metric is calculated from Rrs used for ocean color analyses (see https://doi.org/10.1016/j.rse.2020.111900), but can be made from surface reflectances and used over land as well. Suggested Use: Given that AVW is the apparent color of pixel, it can be used to track changes in land and water surfaces. The AVW value indicates average color reflected from a surface, e.g., healthy vegetation will have AVW in the NIR, water in the blues and greens, and turbid water in the reds. During flood days, the area around the Jacui River gets significantly redder (from previous NIR values), which can indicate turbid water supressing the typical vegetated signal in that area. Also, the Lagoa dos Patos gets significantly redder (from the greens), which indicates different conditions in the water (i.e., injection of sediment, which has average colors in the red). Images are typically displayed using the "Spectral" color map, with bounds from 400 - 700 (see attachment). For the percent change images, negative changes signify shorter average wavelengths (can be thought of as blue-shifting) and positive % changes are elongated average wavelengths (i.e., red-shifts). In other words, these shifting wavelengths tell us that some enviornmental change has caused the average color of a pixel to change. Satellite/Sensor/Resolution: Satellite: PACE, sensor: OCI, temporal resolution: daily, spatial resolution: gridded to 0.015 degrees from a Level 2 product in instrument swath (varying pixel size, 1.2 km at nadir). Credits: Credit: 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

Dates of Images: Pre-Event: 04/20/2024 (pre-flood) Post-Event: 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: This product is the apparent visible wavelength (AVW) of each pixel in a scene, approximating the overall color of the surface. It is calculated by taking the harmonic mean of surface reflectances from 350 nm to 895 nm, and can provide a sense of what has changed in the landscape by comparing several days against each other, as the change in apparent color of a surface often occurs under drastic circumstances. Dates covered include one pre-flood day (04/20/2024) and 5 flood days ending on 05/21/2024 at ~1:00 local time. AVW for each day is delivered, as is a % change from the pre-flood day to each of the 5 flood days afterward, showing the magnitude of color change in the area. Depending on the direction of change, one can infer the type of surface change from AVW. Typically, this metric is calculated from Rrs used for ocean color analyses (see https://doi.org/10.1016/j.rse.2020.111900), but can be made from surface reflectances and used over land as well. Suggested Use: Given that AVW is the apparent color of pixel, it can be used to track changes in land and water surfaces. The AVW value indicates average color reflected from a surface, e.g., healthy vegetation will have AVW in the NIR, water in the blues and greens, and turbid water in the reds. During flood days, the area around the Jacui River gets significantly redder (from previous NIR values), which can indicate turbid water supressing the typical vegetated signal in that area. Also, the Lagoa dos Patos gets significantly redder (from the greens), which indicates different conditions in the water (i.e., injection of sediment, which has average colors in the red). Images are typically displayed using the "Spectral" color map, with bounds from 400 - 700 (see attachment). For the percent change images, negative changes signify shorter average wavelengths (can be thought of as blue-shifting) and positive % changes are elongated average wavelengths (i.e., red-shifts). In other words, these shifting wavelengths tell us that some environmental change has caused the average color of a pixel to change. Users should note that pixels on the edges of masked clouds may see an elevated magnitude of percent change relative to neighboring non-cloud-edge pixels due to the adjacency effect”. Satellite/Sensor/Resolution: Satellite: PACE, sensor: OCI, temporal resolution: daily, spatial resolution: gridded to 0.015 degrees from a Level 2 product in instrument swath (varying pixel size, 1.2 km at nadir). Credits: Credit: 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 Esri REST Endpoint: See URL to the right. WMS Endpoint: https://gis.earthdata.nasa.gov/portal/services/DISASTERS_EX2602_202405_FLOOD_BRAZIL/ex2602_pace_avw/ImageServer/WMSServer

Dates of Images: Pre-Event: 04/20/2024 (pre-flood) Post-Event: 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: This product is the apparent visible wavelength (AVW) of each pixel in a scene, approximating the overall color of the surface. It is calculated by taking the harmonic mean of surface reflectances from 350 nm to 895 nm, and can provide a sense of what has changed in the landscape by comparing several days against each other, as the change in apparent color of a surface often occurs under drastic circumstances. Dates covered include one pre-flood day (04/20/2024) and 5 flood days ending on 05/21/2024 at ~1:00 local time. AVW for each day is delivered, as is a % change from the pre-flood day to each of the 5 flood days afterward, showing the magnitude of color change in the area. Depending on the direction of change, one can infer the type of surface change from AVW. Typically, this metric is calculated from Rrs used for ocean color analyses (see https://doi.org/10.1016/j.rse.2020.111900), but can be made from surface reflectances and used over land as well. Suggested Use: Given that AVW is the apparent color of pixel, it can be used to track changes in land and water surfaces. The AVW value indicates average color reflected from a surface, e.g., healthy vegetation will have AVW in the NIR, water in the blues and greens, and turbid water in the reds. During flood days, the area around the Jacui River gets significantly redder (from previous NIR values), which can indicate turbid water supressing the typical vegetated signal in that area. Also, the Lagoa dos Patos gets significantly redder (from the greens), which indicates different conditions in the water (i.e., injection of sediment, which has average colors in the red). Images are typically displayed using the "Spectral" color map, with bounds from 400 - 700 (see attachment). For the percent change images, negative changes signify shorter average wavelengths (can be thought of as blue-shifting) and positive % changes are elongated average wavelengths (i.e., red-shifts). In other words, these shifting wavelengths tell us that some environmental change has caused the average color of a pixel to change. Users should note that pixels on the edges of masked clouds may see an elevated magnitude of percent change relative to neighboring non-cloud-edge pixels due to the adjacency effect. Satellite/Sensor/Resolution: Satellite: PACE, sensor: OCI, temporal resolution: daily, spatial resolution: gridded to 0.015 degrees from a Level 2 product in instrument swath (varying pixel size, 1.2 km at nadir). Credits: Credit: 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 Esri REST Endpoint: See URL to the right. WMS Endpoint: https://gis.earthdata.nasa.gov/portal/services/DISASTERS_EX2602_202405_FLOOD_BRAZIL/ex2602_pace_percchange/ImageServer/WMSServer

Dates of Images: Pre-Event: 04/20/2024 (pre-flood) Post-Event: 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: OCI Temporal resolution: daily Spatial 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 Esri REST Endpoint: See URL to the right. WMS Endpoint: https://gis.earthdata.nasa.gov/portal/services/DISASTERS_EX2602_202405_FLOOD_BRAZIL/ex2602_pace_ndwi/ImageServer/WMSServer

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: OCI Temporal resolution: daily Spatial 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

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 NDVI images from PACE OCI of the 2024 flooding in Brazil using data from the OCI LANDVI suite, where NDVI is one of the products delivered daily by the mission. The images show how the landscape changes from a pre-flood day (04/20/2024) through flood days ending at 05/21/2024 at ~1:00 pm local time. NDVI is a measure of approximate greenness and health in vegetation but can also be useful in distinguishing water extent and unhealthy vegetated areas, which can be see in these images throughout the flood. Suggested Use: NDVI is a normalized band ratio measuring approximate greenness and vegetation health. Higher positive values mean greener and abundant vegetation, values around 0 mean bare soil or rock, and lower negative values mean non-vegetated areas like water or clouds. These images show the transition of the area around the Jacui River from non-flooded conditions (high NDVI values) to flooded (NDVI values in the negative, indicating water presence). Clouds have been screened from these products, so low NDVI values can around the river can be identified as water. Satellite/Sensor/Resolution: Satellite: PACE, sensor: OCI, temporal resolution: daily, spatial resolution: gridded to 0.015 degrees from a Level 2 product in instrument swath (varying pixel size, 1.2 km at nadir).