This product was developed for the Oregon coast based on the observed change between running 8-day composite chlorophyll-a (CHL) data obtained by the VIIRS aboard the Suomi-NPP spacecraft. This product was optimized to detect bloom onset via satellite in the coastal waters of Oregon, a region typified by high frequency biological variance yet pervasive cloud cover (see McKibben et al. 2012, JGR-Oceans). The product is based on running relative differences between successive 8-day products. A current composite (an average of the previous 8 days) and a reference composite (an average of the 8-day period immediately preceding the current composite). The reference is differenced from the current, then the result is normalized to the reference. Resulting daily imagery highlights the geographic locations of greatest relative change observed between weekly average CHL, providing a way to track onset and advection of active blooms over time. Note the product is optimized to work best in the coastal waters of Oregon, although it is operational further offshore and to the north or south as satellite coverage permits (coverage is increasingly better to the south and worst further offshore and to the north of Oregon). The bloom product accessible from this page is based on the VIIRS CHL product and shows the percent relative change in CHL over time. THIS IS AN EXPERIMENTAL PRODUCT: intended strictly for scientific evaluation by professional marine scientists.