|Towards high-temporal resolution observation of euphotic zone depth in the North Sea|
Lee, Z.; Ruddick, K.; Shang, S.; Nechad, B. (2012). Towards high-temporal resolution observation of euphotic zone depth in the North Sea, in: 44th international Liège colloquium on ocean dynamics "Remote sensing of colour, temperature and salinity – new challenges and opportunities" - May 7-11, 2012. pp. 1
In: (2012). 44th international Liège colloquium on ocean dynamics "Remote sensing of colour, temperature and salinity – new challenges and opportunities" - May 7-11, 2012. GHER, Université de Liège: Liège. 126 pp., more
|Authors|| || Top |
- Lee, Z.
- Ruddick, K., more
- Shang, S.
- Nechad, B., more
Euphotic zone depth (Zeu), practically measured as the depth where photosynthetic available radiation becomes 1% of its surface value, is not only a measure of water clarity, but also an important parameter for modeling of photosynthesis of aquatic environments. Based on radiative transfer and bio-optical models, algorithms have been developed to estimate Zeu from ocean color satellite measurements, such as MODIS/MERIS. These satellites, however, have a repeating cycle greater than a day to take measurements, thus inadequate to address the diurnal variability of water clarity or photosynthesis even if there are no clouds to block the observations. It requires high temporal resolution measurements to resolve such dynamics. For areas in the North Sea, the available high frequency (every 15 min) measurements are from the Spinning Enhanced Visible and InfreRed Imager (SEVIRI), which has measurements around 600 nm that can be related to suspended particulate matter (SPM). This SPM further provides a measure of the scattering coefficient of the water. To estimate Zeu of an aquatic environment, it requires information of both scattering and absorption. To remedy the shortage of absorption measurements from SEVIRI, a scheme to use the low-frequency measurements provided by MODIS/MERIS is developed. The effectiveness and the uncertainties resulted from the mismatch of the temporal frequencies for various regions in the North Sea are also addressed.