Aqua MODIS Level-2 Regional Ocean Color (OC) - Near Real-time (NRT) Data, version 2022.0

The Ocean Biology DAAC produces near real-time (NRT) products using the best-available combination of ancillary data from meteorological and ozone data. As such, the inputs and the calibration used are less than optimal. Near real-time products provide a snapshot of the data during a short time period within a single orbit. The Ocean Color (OC) data suite provides calibrated, atmospherically corrected ocean-optics measurements and derived biogeophysical products. This data suite includes the Apparent Optical Properties (AOP) and provides satellite-derived measures of the interaction between solar radiation and the upper ocean. AOPs are “apparent” because they depend not only on the inherent optical properties (IOPs) of seawater and its constituents but also on the ambient light field. These variables are critical for studying light penetration, primary productivity, and biogeochemical cycling. Geophysical variables in this suite include: - Kd_490 - Diffuse attenuation coefficient at 490 nm, KD2 algorithm (m⁻¹) - Rrs - Remote sensing reflectance (sr⁻¹) - angstrom - Aerosol Angstrom exponent, 443 to 865 nm - chlor_a - Chlorophyll Concentration, OCI Algorithm (mg m⁻³) - l2_flags - Level-2 Processing Flags - aot_869 - Aerosol optical thickness at 869 nm - ipar - Instantaneous Photosynthetically Available Radiation (einstein m⁻² s⁻¹) - nflh - Normalized Fluorescence Line Height (W m⁻² um⁻¹ sr⁻¹) - par - Photosynthetically Available Radiation, R. Frouin (einstein m⁻² day⁻¹) - pic - Calcite Concentration, Balch and Gordon (mol m⁻³) - poc - Particulate Organic Carbon, D. Stramski, 2007 (443/555 version) (mg m⁻³)海洋颜色（Ocean Color, OC）数据集套件提供经过校准与大气校正的海洋光学测量数据，以及衍生的生物地球物理产品。本数据集套件包含表观光学特性（Apparent Optical Properties, AOP），并提供卫星反演得到的太阳辐射与上层海洋相互作用的相关测量结果。表观光学特性之所以称为“表观”，是因为其不仅取决于海水及其组分的固有光学特性（Inherent Optical Properties, IOPs），同时还受环境光场的影响。上述变量对于研究光穿透深度、初级生产力以及生物地球化学循环具有关键意义。 本套件涵盖的地球物理变量如下： • Kd_490：490 nm处的漫衰减系数，采用KD2算法计算，单位为m⁻¹ • Rrs：遥感反射率（sr⁻¹） • angstrom：气溶胶安斯特朗指数，波段范围443~865 nm • chlor_a：叶绿素浓度，采用OCI算法计算，单位为mg m⁻³ • l2_flags：二级处理标志位（Level-2 Processing Flags） • aot_869：869 nm处的气溶胶光学厚度 • ipar：瞬时光合有效辐射（Instantaneous Photosynthetically Available Radiation），单位为einstein m⁻² s⁻¹ • nflh：归一化荧光线高度，单位为W m⁻² μm⁻¹ sr⁻¹ • par：光合有效辐射，采用R. Frouin算法，单位为einstein m⁻² day⁻¹ • pic：方解石浓度，采用Balch与Gordon算法，单位为mol m⁻³ • poc：颗粒有机碳，源自D. Stramski 2007年提出的443/555波段版本算法，单位为mg m⁻³