珠江口真光层颗粒有机碳的遥感研究

Seawater particulate organic carbon (POC) is thought to be an important component controlling the ocean carbon sequestration process, through transporting carbon to deeper waters. The latest release of the standard surface POC product has great uncertainty in estuaries and coastal waters. And using satellite remote sensing to estimate surface POC in the Pearl River Estuary (PRE) has not been reported previously. Retrieval of POC from space has long been restricted to the surface layer. However, the origins of POC, including the phytoplankton, detrital particles and heterotrophic bacteria, etc., occur not only in the surface layer but also in the water column. Therefore, the objective of this study is to estimate the POC over the euphotic layer in the PRE using satellite remote sensing data. The remote sensing model of surface POC concentration will be developed for the Pearl River Estuary based on the in situ data. Meanwhile, the vertical POC distribution over the euphotic layer will be identified in dry and wet seasons using profile data. By integrating the surface POC remote sensing model and vertical POC distribution, the remote sensing model will be developed to derive the POC over the euphotic layer. The high spatial resolution of the euphotic layer POC products will be obtained using Moderate Resolution Imaging Spectroradiometer (MODIS), MEdium Resolution Imaging Spectrometer (MERIS), Visible Infrared Imaging Radiometer Suite (VIIRS), and the upcoming launch of the Ocean and Land Colour Instrument (OLCI). The development of the model will extend the remote sensed POC coverage from the surface layer to the entire euphotic layer and from the open ocean to the estuarine and inshore waters. The euphotic layer POC products will provide more reliable satellite observations for improvement and evaluation of the biogeochemical and ecosystem models in the Pearl River Estuary, and improve understanding of the carbon transport, deposition and storage processes of Pearl River Estuary.

海水的颗粒有机碳（POC）能将碳向深层输运，是海洋固碳过程一个重要组成。目前发布的大洋表层POC产品在近岸河口存在很大不确定性，适用于珠江口表层POC遥感算法尚未见报道。卫星对海洋POC的遥感通常限制在水体表层，由于POC的来源和组成（浮游植物、碎屑颗粒等）不只发生在表层而是在整个水柱中，因此有必要对整个真光层POC进行估算。本项目拟采用光学卫星数据估算珠江口真光层POC。我们将基于珠江口实测数据，对比三种方法建立的珠江口表层POC遥感模型，并分别研究旱季和雨季真光层POC垂向分布模型，以获得真光层内POC的遥感估算方法。项目将采用多源遥感数据获取高空间分辨率的珠江口真光层POC分布，将POC的遥感覆盖从表层延伸到整个真光层；从大洋延伸到近岸河口。项目将为海洋生物地球化学模型的改进提供更可靠的卫星观测，有利于增进对珠江口碳输运、沉降和储存过程的认识。

海水的颗粒有机碳（POC）是海洋固碳过程一个重要组成。目前适用于珠江口表层POC遥感算法尚未见报道，由于POC的来源和组成（浮游植物、碎屑颗粒等）不只发生在表层而是在整个水柱中，因此有必要对整个真光层POC进行估算。本项目基于四个航次的珠江口实测数据，分别研究旱季和雨季真光层POC垂向分布模型，发现雨季POC垂向分布遵循二次多项式关系，而旱季POC垂向分布遵循指数关系。同时基于POC与水色参数和遥感反射比关系建立了真光层内POC的遥感估算模型，发现雨季真光层POC与叶绿素存在显著相关，旱季遥感反射比估算的真光层POC精度更高。同时采用MODIS，VIIRS等遥感数据，获取了高空间分辨率的珠江口真光层POC分布，发现雨季，高浓度的真光层POC主要出现在入海口，而旱季，高浓度的真光层POC主要出现在珠江口口门附近。本项目实现了将POC的遥感覆盖从表层延伸到整个真光层；从大洋延伸到近岸河口。研究结果为海洋生物地球化学模型的改进提供更可靠的卫星观测，有利于增进对珠江口碳输运、沉降和储存过程的认识。