摘要
The hydrographic and bio-optical properties of the Bering Sea shelf were analyzed based on in-situ measurements obtained during four cruises from 2007 to 2009.According to the temperature and salinity of the seawater,the spring water masses on the Bering Sea shelf were classified as the Alaskan Coast Water,Bering Sea Shelf Water,Anadyr Water,Spring Mixed Layer Water,Remnant Winter Water,and Winter Water,each of which had varying chlorophyll a concentrations.Among them,the highest chlorophyll a concentration occurred in the nutrient-rich Anadyr Water((7.57±6.16)mg/m^(3) in spring).The spectrum-dependent diffuse attenuation coefficient(Kd(λ))of the water column for downwelling irradiance was also calculated,exhibiting a decrease at 412-555 nm and then an increase within the range of 0.17-0.48 m-1in spring.Furthermore,a strong correlation between the chlorophyll a concentration and the attenuation coefficient was found at visible wavelengths on the Bering Sea shelf.Spatially,the chlorophyll a concentration was higher on the northern shelf((5.18±3.78)mg/m^(3))than on the southern shelf((3.64±2.51)mg/m^(3)),which was consistent with the distribution of the attenuation coefficient.Seasonally,the consumption of nutrients by blooms resulted in minimum chlorophyll a concentration((0.78±0.51)mg/m^(3))and attenuation coefficient values in summer.In terms of the vertical structure,both the attenuation coefficient and the chlorophyll a concentration tended to reach maximum values at the same depth,and the depth of the maximum values increased as the surface temperature increased in summer.Moreover,an empirical model was fitted with a power function based on the correlation between the chlorophyll a concentration and the attenuation coefficient at 412-555 nm.In addition,a spectral model was constructed according to the relationship between the attenuation coefficients at 490 nm and at other wavelengths,which provides a method for estimating the bio-optical properties of the Bering Sea shelf.
基金
The State Key Program of National Natural Science Foundation of China under contract No.41941012
the National Key R&D Program of China under contract No.2018YFA0605903
the National Natural Science Foundation of China under contract Nos 41776192 and 41976218。
