Estimating the diffuse attenuation coefficient from moderatespatial resolution, multi-spectral satellite data in a seagrass environment

Currently, spatial light attenuation and water clarity can be estimated from diffuse attenuation coefficient at wavelength 490 nm (Kd
₄₉₀
) available from satellite data. In the present study, we investigated the performance of existing satellite Kd
₄₉₀
algorithms in near-shore seagrass environment using available in situ data. We also examined the use of moderate-spatial resolution, multispectral imagery data of Landsat and ALOS AVNIR-2 to estimate both measured and calculated Kd
₄₉₀
. Finally, we demonstrated conceptually on how Kd
₄₉₀
can be related to Kd of photosynthetically available radiation (K
_dPAR
). The results showed that existing Kd
₄₉₀
algorithms can be used to estimate in situ Kd
₄₉₀
for sites with Kd
₄₉₀
<; 1 m
^-1
. Systematic and strong relationships were observed between blue-green ratio of Landsat and AVNIR 2 bands, and either in situ Kd
₄₉₀
or calculated Kd
₄₉₀
from MERIS/MODIS algorithms. For some selected sites K
_dPAR
can be well reconstructed from Kd
₄₉₀
using empirical model from which correlation between Kd
₄₉₀
and K
_dPAR
can then be developed.