An Estimation of Light Attenuation in Shallow Estuary using In-situ Observations and Multispectral Satellite Imagery
A methodology is used to predict the underwater light field using data from the WorldView-3 (WV-3) multispectral satellite sensor. WV-3 multispectral imagery is analyzed to estimate reflectance above the water surface, followed by application of empirical algorithms at different water depth locations to estimate light attenuation and penetration depths in shallow water. This approach uses (a) full bit resolution WV-3 imagery, (b) top of atmosphere spectral radiance to estimate reflectance at the sensor and (c) atmospheric corrections to estimate water surface reflectance just above the water. After the water reflectance is obtained, it is used to correct for water surface wave glint effects. Glint is caused by wave facets and is visible in high spatial resolution multispectral images. Glint corrected images are then used to estimate light attenuation depths, a measure of underwater light penetration depths and visibility in water. In-situ data from a hyperspectral sensor is also used to determine light attenuation coefficients and depths in the Indian River Lagoon. The in-situ measurements are compared to satellite based estimates of light penetration depths from WV-3 imagery.