Ocean Ledger’s Post

𝟱𝟬 𝘀𝗵𝗮𝗱𝗲𝘀 𝗼𝗳 𝘁𝗿𝗼𝗽𝗶𝗰𝗮𝗹 𝗰𝗼𝗮𝘀𝘁𝗮𝗹 𝗲𝗻𝘃𝗶𝗿𝗼𝗻𝗺𝗲𝗻𝘁𝘀: 5-m NICFI - Norway's International Climate and Forest Initiative Planet mosaic of the broader Bombetoka Bay (NW Madagascar) - a global hot spot of coastal #bluecarbon and #biodiversity, but also wide-ranging #waterquality and #turbidity. This 113x49.6-km mosaic showcases the variability but also the arising challenges of coastal aquatic #remotesensing, especially in tropical waters and environments. Tropical coastal systems typically exhibit up to 90% of cloud coverage annually, which impedes traditional single image-based approaches. On top of cloud and, thus, cloud shadow impedances, persistent seasonal and yearlong turbidity - as the case of the depicted Bombetoka Bay - additionally blocks light penetration, further challenging high-confidence detection of any seabed property (e.g. seagrasses, corals, bathymetry). Bombetoka Bay has experienced a dramatic increase in sediment transport via the Betsiboka river during the past 30 years, which is being deposited in the estuary and the offshore delta lobes, among predominantly mangrove stands and coral reefs and seagrass meadows, onshore and nearshore, respectively. Broadly, along the west Madagascar coastline, the main composition of suspended sediments that shape water quality originates from laterites - iron and aluminum-rich rocks that are severely transformed by tropical weathering on the Madagascar highlands - turning the waters red. Other coastal environments of the world feature different hues (e.g. brown, yellow, green) depending on the nature of the #sedimentation and upstream source e.g. marine mud, fluvial sediments, nutrients and by-products of human activities. In addition to yearlong cloud and turbidity intensity, there are also other natural usual suspects that impede #EarthObservation-guided assessments of coastal waters, e.g. sunglint, waves, that are more pronounced in different wavelengths. The described natural complexities and challenges highlight the importance of the availability of near-daily high-resolution satellite imagery, like Planet's deep temporal archive, paired with suitable satellite tech analytics with suitable pre-processing and #analysisreadydata algorithms. But they also highlight the need to integrate #ecological and #geomorphological knowledge in large-scale spaceborne assessments to better characterize the trajectory, condition & ecology of coastal environments. Through the Planet's Startup Program, Ocean Ledger has access to near-daily high-resolution archive from 2014 to today, allowing us to flexibly toggle our analytics to resolve the aforementioned challenges in a purely automated and highly scalable fashion. This enables high-confidence granular historical, baseline and scenario analyses of coastal indicators, insights and risks through a unique fusion of remote sensing, cloud computing, biophysical modelling and field data. Image Credit: Planet Labs PBC