The 8-day composite product is generated from daily red band difference (RBD) products by selecting the maximum RBD value for each non-land pixel over the past 4 days. If no valid RBD value is identified from the past 4 days, the last valid RBD value from the past 8 days is used. Before compositing the daily RBD products a high glint mask is applied and followed by a median filter using a 5x5 pixel window. The RBD product is a measure of chlorophyll fluorescence (dimensionless). Details on the algorithm may be found in the NOAA Technical Memorandum available at https://repository.library.noaa.gov/view/noaa/30906. The RBD values are scaled between 0-250. They may unscaled by applying the following equation: 10**(DN / 150. - 4) where DN is the scaled pixel value. Pixel values key: val colors description 0 Black non-detection 1-250 purple to red valid data (cooler colors indicate low levels and warmer colors indicate high levels) 252 off-white land 253-254 grey cloud or invalid 255 dark grey no data RBD_v2_cbar_vert.png contains a legend for the RBD product. ------------------------------------------ The file naming conventions are herein described. For information on interpreting the satellite imagery, visit https://coastalscience.noaa.gov/research/stressor-impacts-mitigation/hab-monitoring-system/more-information/. For additional information about the Gulf of Mexico HAB Operational Forecast System, visit https://coastalscience.noaa.gov/research/stressor-impacts-mitigation/hab-forecasts/gulf-of-mexico/faqs/. ------------------------------------------ Sentinel-3 OLCI RBD 8-day composite files ------------------------------------------ comp_YYYY.MMDD_MMDD.L4..rbd_rhos..tif e.g. comp_2022.0719_0726.L4.FL.rbd_rhos.max4.8day.tif comp = denotes a composite product YYYY = start year of composite MMDD_MMDD = composite start and end date range where MM is month and DD is day of month L4 = denotes product level = geographic region code ("FL" - Florida or "TX" - Texas) rbd_rhos = name of daily product composite generated from = "max4.8day" (8-day composite with max from last 4 days) tif = denotes file type (in this case GeoTIFF)