Organic carbon remote sensing monitoring—providing important data for marine climate research

Today, the marine carbon cycle plays a crucial role in regulating global climate change under the influence of CO2 and has been a hot topic of international research. Studies show that about half of the CO2 emitted into the atmosphere by humans each year is absorbed by the ocean and converted into particulate organic carbon (POC) through phytoplankton photosynthesis, which is then fixed by sedimentation. POC is organic particulate matter produced by marine organism metabolism, sediment resuspension, and terrestrial inputs, including phytoplankton cells, bacteria, and organic debris, and is the main form of carbon sequestration and migration out of seawater. Marine particulate organic carbon (POC) is of great significance to the marine carbon cycle and the regulation of global climate change under the influence of CO2.

Marine organic carbon remote sensing monitoring

In marine carbon cycle research, remote sensing technology is a crucial method for acquiring seawater particulate organic carbon (POC) information. POC remote sensing monitoring and spatial modeling have become hot scientific issues in the marine field. Ocean color satellites can monitor global marine phytoplankton biomass and primary productivity. Chlorophyll concentration and sea surface particulate organic carbon (POC) concentrations, which are spectrally responsive water body concentrations, are routine products of ocean color analysis. With the continuous improvement of imaging spectrometer specifications, the spatial, temporal, and spectral resolutions of ocean color satellites have significantly increased, providing better technical support for remote sensing inversion.

Marine organic carbon remote sensing inversion algorithm

Currently, the main water quality parameters that can be obtained through water color remote sensing include chlorophyll, suspended sediment, and colored soluble organic matter. Among these, some biogeochemical processes of POC link it to chlorophyll, suspended matter, and other substances, as well as inherent optical quantities such as the light attenuation coefficient and backscattering coefficient of particulate matter. This information serves as the basis for optical remote sensing, enabling remote sensing inversion of POC.There are two types of POC remote sensing inversion algorithms: one is an empirical algorithm based on apparent optical quantities, and the other is a semi-analysis algorithm based on inherent optical quantities.  

CAS Xi'an Optics & Aerospace - Marine Organic Carbon Inversion

Based on the POC dataset retrieved from remote sensing data, the spatiotemporal variation patterns of POC concentration in the South my country Sea can be analyzed.As can be seen from the inversion chart, the POC values ​​are relatively high along the coast of the South China Sea, especially near the Taiwan Strait and Qionghai Sea.  

The results of a comprehensive remote sensing assessment of marine carbon parameters indicate that as the partial pressure of atmospheric CO2 rises rapidly, the pCO2 of seawater also increases, but at a lower rate than that of atmospheric CO2.Therefore, the global ocean carbon sink has shown an increasing trend year by year, but different sea areas also have significant regional characteristics.Against the backdrop of global change, the response of marine biological pumps is highly complex. Despite the significant decline in chlorophyll concentration and primary productivity in most sea areas over the past 20 years, the downward output of particulate organic carbon has not shown a significant trend, indicating a decoupled change between primary production and vertical output.

Currently, remote sensing of particulate organic carbon (POC) has become an important tool for studying POC in the ocean. Establishing a remote sensing monitoring model is crucial for achieving accurate POC remote sensing monitoring. In-depth research into the optical remote sensing mechanism of POC can improve our understanding of the optical characteristics of POC in different sea areas. Establishing a three-dimensional marine observation system that combines surface and vertical distribution of POC represents the future trend of remote sensing monitoring of particulate organic carbon.