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赤潮爆发时水体叶绿素a质量浓度升高,引起浮游植物吸收系数、光束总吸收系数等水体固有光学性质(IOP)的变化,并导致水体表观光学性质(AOP)的改变。海洋光学浮标可实现水体表观光学性质的定点连续时间序列观测,基于此发展相应的模型方法有望实现赤潮生消全过程的监测。利用一次赤潮生消过程的海洋光学浮标数据,发展了一种赤潮半分析监测方法。该方法首先由光学浮标数据得到的水体光谱漫衰减系数Kd(λ)和遥感反射率rrs(λ),结合经验确定的水下光场平均余弦进行水体光束总吸收系数a(λ)的半分析估算,然后再半分析反演浮游植物吸收系数aph(λ)和叶绿素a质量浓度。经检验,该方法估算a(675),aph(675)和叶绿素a质量浓度的中值相对误差分别为8.6%,34.9%和38.9%。将本方法与半分析方法(QAA)和统计回归方法进行了对比分析,本方法的优势在于反演精度较高,所采用的经验参数大都源自辐射传输理论计算、不依赖于浮标数据且对反演结果的影响有限。
When the red tide burst, the mass concentration of chlorophyll a increased, causing changes of IOP, such as phytoplankton absorption coefficient and total beam absorption coefficient, and resulted in the change of apparent optics (AOP). The ocean optical buoy can realize the fixed-point continuous time series observation of the apparent optical properties of water bodies. Based on this, the corresponding model method is expected to monitor the whole process of red tide generation. Using a marine optical buoy data from a red tide depletion process, a method of semi-analytical monitoring of red tide development has been developed. The method first analyzes the diffuse attenuation coefficient Kd (λ) and the remote sensing reflectance rrs (λ) of the water body obtained from the optical buoy data, and then semi-analyzes the total absorption coefficient a (λ) of the water body with the average cosine of underwater light field determined empirically. Estimated, and then semi-analytical inversion phytoplankton absorption coefficient aph (λ) and chlorophyll a mass concentration. The test estimated that the median relative error of a (675), aph (675) and chlorophyll a concentration were 8.6%, 34.9% and 38.9%, respectively. This method is compared with the semi-analytical method (QAA) and statistical regression method. The advantage of this method is that the inversion accuracy is high. Most of the empirical parameters used are derived from the theory of radiative transfer and are independent of the buoy data. The effect of inversion is limited.