PACE OCI Level-3 Global Mapped Ocean Color Inherent Optical Properties (OC_IOP) Data, version 3.2

The Inherent Optical Properties (IOP) suite provides per-pixel inherent optical properties - quantities that describe how seawater and its constituents absorb and scatter light, independent of illumination or viewing geometry. IOPs are retrieved from spectral Remote Sensing Reflectance (Rrs) using the default configuration of the Generalized Inherent Optical Properties (GIOP) model framework. These products support water-type classification, water-clarity assessment, biogeochemical studies, and forward/adjoint radiative-transfer applications, and they enable more robust cross-sensor comparisons than purely apparent (AOP) products.

The hyperspctral band list is found in the science data file metadata.

Geophysical variables in this suite include:
- Kd - Diffuse attenuation coefficient of downwelling irradiance (m^-1)
- a - Total absorption coefficient (sum of pure water + phytoplankton + CDOM/detritus, m^-1)
- bb - Total backscattering coefficient (m^-1)
- aph - Phytoplankton absorption coefficient (m^-1)
- aph_unc_442 - Uncertainty in absorption due to phytoplankton at 442 nm (m^-1)
- adg_442 - Combined CDOM + non-algal detritus absorption coefficient at 442nm (m^-1)
- adg_unc_442 - Uncertainty in absorption due to gelbstoff and detrital material at 442 nm (m^-1)
- bbp_442 - Particulate backscattering coefficient at 442nm (m^-1)
- bbp_unc_442 - Uncertainty in particulate backscattering at 442 nm (m^-1)
- rrsdiff - Fractional mean Rrs difference (reconstructed from inverted IOPs - input) (unitless)

固有光学特性（Inherent Optical Properties, IOP）数据集套件提供逐像素固有光学特性——一类用于描述海水及其组分如何吸收、散射光线，且与光照条件或观测几何无关的物理量。固有光学特性通过广义固有光学特性（Generalized Inherent Optical Properties, GIOP）模型框架的默认配置，从光谱遥感反射率（Remote Sensing Reflectance, Rrs）中反演得到。此类产品可支持水体类型分类、水体透明度评估、生物地球化学研究以及正演/伴随辐射传输应用，相较于纯表观光学特性（Apparent Optical Properties, AOP）产品，能够实现更可靠的跨传感器比对。
高光谱波段列表可在科学数据文件的元数据中获取。

本数据集包含以下地球物理变量：
- Kd：下行辐照度漫衰减系数（单位：m⁻¹）
- a：总吸收系数（纯水+浮游植物+有色溶解有机物（Colored Dissolved Organic Matter, CDOM）/碎屑的总和，单位：m⁻¹）
- bb：总后向散射系数（单位：m⁻¹）
- aph：浮游植物吸收系数（单位：m⁻¹）
- aph_unc_442：442 nm处浮游植物吸收的不确定性（单位：m⁻¹）
- adg_442：442 nm处有色溶解有机物与非藻类碎屑的综合吸收系数（单位：m⁻¹）
- adg_unc_442：442 nm处黄质与碎屑物质导致的吸收不确定性（单位：m⁻¹）
- bbp_442：442 nm处颗粒物后向散射系数（单位：m⁻¹）
- bbp_unc_442：442 nm处颗粒物后向散射的不确定性（单位：m⁻¹）
- rrsdiff：归一化平均遥感反射率差（由反演固有光学特性重构得到，与输入值对比，无单位）