Distribution of phytoplankton content in the Kara Sea according to aircraft laser sounding data
Yu.S. Balin, G.P. Kokhanenko, M.G. Klemasheva, S.V. Nasonov, M.M. Novoselov, I.E. Penner
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: lidar, laser-induced fluorescence, Raman scattering, chlorophyll a concentration
Abstract
The article presents the results of aircraft lidar measurements of the spatial distribution of the relative concentration of chlorophyll- a in the surface waters of the Kara Sea. The chlorophyll concentration was determined by the laser-induced fluorescence method. For normalization, the intensity of the Raman scattering signal of water radiation was simultaneously recorded. The results of the spatial distribution of the normalized fluorescence intensity were obtained at three sites in the southwestern region of the Kara Sea. For two sites in the shelf zone near the western coast of the Yamal Peninsula, the spatial distribution of the fluorescence intensity is quite uniform with variation coefficients of 9 and 15%. The third site in the northern tip of the Yamal Peninsula is characterized by a strong influence of continental river runoff, which is manifested in the presence of sharp frontal zones with scales of 5-10 km, where the variation coefficient of the normalized fluorescence intensity Cl reaches 40%. The variation in Cl values in this section is mainly due to the strong variability of the Raman normalization signals and, to a much lesser extent, to the change in fluorescence intensity. Factors influencing the variability of Raman signals are considered. Synchronous in-situ measurements from a ship and remote measurements from an aircraft allowed us to estimate the dimensional calibration coefficient kCl = 1.03 ± 0.09 μg/l for the first two sections of the Kara Sea surface water sounding.
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