Method for inversing depth of subsurface chlorophyll-a maxima of oceanic water body based on remote sensing reflectance

A method for inversing a depth of a subsurface chlorophyll-a maxima (SCM) of an oceanic water body based on remote sensing reflectance, the method comprising:

• step 1, band selection, comprising:
• obtaining a remote sensing reflectance data from a moderate-resolution imaging spectroradiometer (MODIS) remote sensing data, and selecting target remote sensing reflectance data corresponding to three bands of 412 nanometers (nm), 555 nm and 678 nm from the remote sensing reflectance data;
• step 2, R value calculation, comprising:
• calculating a difference between a remote sensing reflectance corresponding to the band 412 nm from the target remote sensing reflectance data and a remote sensing reflectance corresponding to the band 678 nm from the target remote sensing reflectance data, and calculating a ratio of the difference to a remote sensing reflectance corresponding to the band 555 nm from the target remote sensing reflectance data as a R value;
• step 3, data collection, comprising:
• obtaining groups of global measured biogeochemical-automatic reporting oceanographic observers (BGC-Argo) chlorophyll-a concentration profile data, fitting a BGC-Argo chlorophyll-a profile by using a Gaussian function according to the groups of global measured BGC-Argo chlorophyll-a concentration profile data, calculating a depth of an SCM of each group of the groups of global measured BGC-Argo chlorophyll-a concentration profile data according to the BGC-Argo chlorophyll-a profile, as ZSCM, and recording BGC-Argo latitude and longitude data;
• step 4, model construction, comprising:
• matching the BGC-Argo latitude and longitude data with MODIS remote sensing reflectance corresponding to latitudes and longitudes, obtaining a grid point through BGC-Argo latitude and longitude positioning, obtaining remote sensing reflectance data of two grid points around the grid point, calculating groups of R values according to the remote sensing reflectance data of the two grid points, averaging the obtained the groups of R values to obtain a group of data, and matching the groups of global measured BGC-Argo chlorophyll-a concentration profile data with the group of data to obtain a group of depths of SCM, taking the group of data as an input feature and the group of depths of SCM as an output feature to thereby obtain a matching data set, and drawing a scatter plot for ZSCM and R value by using the matching data set to thereby obtain a nonlinear model;
• and
• step 5, ZSCM calculation, comprising:
• obtaining, according to the nonlinear model obtained in the step 4, a function expression of the nonlinear model, and performing regression processing based on the function expression of the nonlinear model and the group of depths of SCM to obtain the depth of the SCM of the oceanic water body.