DOI: 10.5281/zenodo.18630080
title: A Synthetic Bio-Optical Dataset for Danjiangkou Reservoir: Hyperspectral Reflectance and Inherent Optical Properties

description: Summary

This dataset contains 10,000 samples of synthetic bio-optical data generated specifically for the optical characteristics of Danjiangkou Reservoir (China). It was created using the Danjiangkou Bio-Optical Model (DBOM) forward simulation framework.

The dataset links biogeochemical concentrations (Chlorophyll-a, Inorganic Suspended Matter, CDOM) and phytoplankton community structure (Cyanobacteria, Green algae, Brown algae) to Inherent Optical Properties (IOPs) and hyperspectral Remote Sensing Reflectance ($R_{rs}$). The dataset contains the stochastic perturbation of bio-optical parametrization coefficients (e.g., spectral slopes, specific absorption coefficients), which were randomized by $\pm 30\%$ around their local default values to simulate natural variability and support algorithm uncertainty analysis.

Data Generation Methodology





Concentration Generation: Input concentrations were generated using a multivariate log-normal distribution to mimic natural covariance. Phytoplankton community fractions were generated using a Dirichlet distribution.




Forward Modeling:





IOP Model: Localized bio-optical models for Danjiangkou Reservoir were used to compute absorption ($a$) and backscattering ($b_b$) coefficients.




Parameter Perturbation: Key bio-optical parameters (including $S_{cdom}$, $S_{nap}$, $a^*_{ph}$, etc.) were independently perturbed using a uniform distribution $U(0.7, 1.3)$ for each sample to introduce realistic optical complexity.




Radiative Transfer: Remote sensing reflectance ($R_{rs}$) was derived from IOPs using the semi-analytical model by Lee et al. (2011).






Spectral Resolution: Hyperspectral data covering 350 nm to 900 nm with a 2 nm interval.



File Structure

The data is stored in a single NetCDF file (.nc) compatible with Xarray and other multidimensional array libraries.





Dimensions:





sample_id: 10,000 (Number of samples)




wavelen: 276 (Spectral bands from 350 to 900 nm)






Data Variables (Outputs):





Rrs: Remote Sensing Reflectance [$sr^{-1}$]




aph: Absorption coefficient of phytoplankton [$m^{-1}$]




ad: Absorption coefficient of detritus/non-algal particles [$m^{-1}$]




acdom: Absorption coefficient of CDOM [$m^{-1}$]




bbp: Particulate backscattering coefficient [$m^{-1}$]




bp: Particulate total scattering coefficient [$m^{-1}$]






Coordinates (Inputs & Truth Data):





Chla: Chlorophyll-a concentration [$mg/m^3$]




ISM: Inorganic Suspended Matter concentration [$g/m^3$]




ag440: CDOM absorption at 440 nm [$m^{-1}$]




frac_cyano, frac_green, frac_brown: Fractional composition of phytoplankton groups (0-1).




Perturbed Parameters: The file also records the specific randomized parameters used for each sample (e.g., S_cdom, A_ph, gamma_nap) to allow for sensitivity analysis.





Potential Applications





Development and validation of semi-analytical algorithms for inland waters.




Training machine learning models for water quality retrieval.




Phytoplankton functional type (PFT) discrimination studies.




Sensitivity analysis of bio-optical inversion algorithms.



Technical Info





Format: NetCDF4




Compression: zlib (level 9)




Code Author: Shun Bi (bishun@niglas.ac.cn)