[A-CG41] Satellite Earth Environment Observation

[ACG41-P23] Hyperspectral Ocean Color Measurements at the Okhotsk Tower, Hokkaido, Japan.

*Takafumi Hirata¹, Natsuhiko Otsuka², Katsushi Iwamoto³, Seiji Katakura³ (1.Arctic Research Center, Hokkaido University, 2.Okhotsk Sea Ice Museum, 3.City of Mombetsu)

Keywords:Hyperspectral, Ocean Color

A hyperspectral radiometer system was installed at the Okhotsk Tower (Hokkaido, Japan) to collect in-situ ocean color data. Temporal variations of the observed radiometric quantities showed both non-periodic and periodic (i.e. diurnal) variations, the latter of which was associated with a variation of the solar altitude. The acyclic variations of the observed radiance reflected at the sea surface also showed spectral variations, implying changes in bio-geochemical properties of seawater over the observation period. Principal Component Analysis (PCA) of the normalized hyperspectral ocean reflectance showed four major modes, very consistent with the previous studies in the Atlantic. However, a further analysis indicated that these modes were associated with composite properties of biogeochemical factors, rather than individual factors suggested by the previous studies. Notably, our PCA spectra could be reproduced by a combination of correlation spectra obtained between the ocean reflectance and the individual biogeochemical factors as well as by a correlation spectrum obtained between the reflectance and an marine environment property that reflects the multiple biogeochemical properties. Thus, our study showed the statistical results very similar to the previous studies but provided a different interpretation for the results.