SUN-STIMULATED CHLOROPHYLL FLUORESCENCE .2. IMPACT OF ATMOSPHERIC PROPERTIES

The Sun-stimulated chlorophyll fluorescence is a small but significant property of phytoplankton which can be detected using remote-sensing techniques. Besides the influence of oceanic properties, chlorophyll fluorescence is masked by atmospheric extinction. While an increase in chlorophyll concentration of 1 mg/m3 causes an increase in the upwelling radiances of about 003Wm-2sr-lpm-l just above the water surface and due to the chlorophyll fluorescence, the upward radiances measured at AF = 685nm and at the top of the atmosphere ranges from 8 to 20Wm-2 sr-1 μm-1 for realistic atmospheric turbidity variations and a solar zenith distance of Bs=50-7°. Additionally, the fluorescence, peaking at λF = 685nm with a half-width of about 10 nm, is reduced by the absorption of 02 and H20. However, the fluorescence signal is nearly unaffected, when wavelengths λ≥686nm are exluded and a spectral interval of ∆λF = 5nm is used for the radiance measurements. © 1990 Taylor & Francis Group, LLC.