Official Journal of the Asia Oceania Geosciences Society (AOGS)
Table 4 Three algorithms for differentiation of \(P.donghaiense\) and diatom blooms
From: Use of GOCI-II images for detection of harmful algal blooms in the East China Sea
Algorithm | MODIS | GOCI-II | Threshold value | References |
|---|---|---|---|---|
\({\text{BI}}=\frac{({R}_{rs}({\lambda }_{1})-{R}_{rs}({\lambda }_{2}))/({\lambda }_{1}-{\lambda }_{2})}{({R}_{rs}({\lambda }_{3})-{R}_{rs}({\lambda }_{4}))/({\lambda }_{3}-{\lambda }_{4})}\) | \({\lambda }_{1}=488\), \({\lambda }_{2}=443\) \({\lambda }_{3}=555\), \({\lambda }_{4}=531\) | \({\lambda }_{1}=490\), \({\lambda }_{2}=443\) \({\lambda }_{3}=555\), \({\lambda }_{4}=510\) | If \(0<{\text{BI}}\le 0.3\), \(P.donghaiense\); If \(0.3<{\text{BI}}\le 1.0\), diatom | Shang et al. (2014) |
\({\text{PDI}}=\frac{{R}_{rs\_slope}(\lambda , { \lambda }^{+})-{R}_{rs\_slope}({\lambda }^{+},{ \lambda }^{-})}{{R}_{rs}(\lambda )-{R}_{rs}\left({\lambda }^{-}\right)}\) *2 \({\text{DI}}=\frac{{R}_{rs}({\lambda }_{1})-[{R}_{rs}(\lambda )+\frac{(\lambda -{\lambda }_{1})}{(\lambda -{\lambda }_{2})}\times ({R}_{rs}({\lambda }_{2})-{R}_{rs}(\lambda ))]}{{R}_{rs}({\lambda }_{1})}\) | \({\lambda }^{+}=531\), \({\lambda }^{-}= 488\) \(\lambda= 555\), \({\lambda }_{1}=645\), \({\lambda }_{2}=667\) | \({\lambda }^{+}=510\), \({\lambda }^{-}= 490\) \(\lambda= 555\), \({\lambda }_{1}=620\) \({\lambda }_{2}=660\) | If \({\text{DI}}<25\times {\text{PDI}}-0.125\), \(P.donghaiense\); If \({\text{DI}}\ge 25\times {\text{PDI}}-0.125\), diatom | Tao et al. (2015) |
\({R}_{\_slope}={{\text{tan}}}^{-1}(100\times (1-({R}_{rs}({\lambda }_{2})-{R}_{rs}({\lambda }_{1}))/({\lambda }_{2}-{\lambda }_{1})\) | \({\lambda }_{1}=667\), \({\lambda }_{2}=555\) | \({\lambda }_{1}=660\), \({\lambda }_{2}=555\) | \(\mathrm{if }{R}_{\_slope}>0.4,\) \(P.donghaiense\); if \({R}_{\_slope}<0.4,\) \(diatom\) | Shen et al. (2019b) |