The FLOOD viewer facilitates the use and evaluation of NASA's Land, Atmosphere Near real-time Capability for Earth observation (LANCE) flood products by allowing the user to browse globally and over time and to compare to other flood products.
LANCE provides two global daily near-real time (NRT) flood products at ~250m resolution:
- MODIS product (MCDWD) generated from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument imagery on the Terra and Aqua platforms;
- VIIRS product (VCDWD) generated from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument imagery on the NOAA-20 (JPSS-1) and NOAA-21 (JPSS-2) platforms.
MCDWD was released in 2021, succeeding the MWP predecessor product that was launched in 2011. VCDWD was released in April 2025. Apart from the different input data source (MODIS or VIIRS), the two products are otherwise the same in algorithm and product formats. With the Terra and Aqua satellites expected to be retired in 2026-27, the VIIRS product was developed to replace the MODIS product.
Additional flood products or flood-relevant layers have been made available in the viewer: the NOAA-GMU VIIRS flood product; the Copernicus GFM (Sentinel-1/SAR based); and the NASA OPERA surface water products (HLS and Sentinel-1 based).
In the viewer, the default "basic" mode provides a simplified interface with fewer flood products for new users to explore. For instance, it only includes the NASA 2-day composite products, as this is generally recommended for an initial look. The "advanced" tab adds the 1-day and 3-day products, along with other flood and water products.
If no clouds are present, the 1-day product is likely the most useful and up-to-date. However, in the presence of clouds, the 1-day product can be contaminated with cloud-shadow false-positives, so the user must compare the source imagery from MODIS or VIIRS to the flood product. This can also occasionally affect the 2-day product, so it is recommended to review the visible imagery in conjunction with any flood product to aid interpretation.
- NRT Global Flood Products and Data Access/Download
- MODIS/VIIRS NRT Global Flood Products (PDF)
- FAQ of flood products
Web Services: NASA MODIS and VIIRS flood product imagery that is viewable in the FLOOD viewer and in NASA's Worldview are also available as GIBS layers. For details, please see: