东亚地区沙尘循环的卫星定量遥感评估

Trans-Pacific transportation of East Asian dust aerosols is the largest scale of the dust transmission process on Earth. It produces very important effect on global environment, ecosystem, weather systems, and climate. Therefore, deep understanding of dust cycle associated with them over East Asian area has essential scientific significance in global climate change study with the core of coupling ocean-land-atmosphere process. In this project, A-Train satellite products, meteorological station records, ground-based observation, reanalysis data, and HYSPLIT trajectory model will be integrated into the composite analysis of dust transportation pathways over East Asia. The main pathways will be extracted under different atmospheric circulation backgrounds. The advantage of lidar-based active remote sensing will be used to effectively distinguish dust and background aerosols and furtherly derive the dust optical property parameters which are required in satellite-based estimation of the dust flux. A new satellite-based retrieval algorithm will be built and applied to derive the dust fluxes of emission, transportation and deposition over East Asia. We will come to a better understanding of East Asia dust cycle by comparing and analyzing the difference of dust emission, transportation and deposition fluxes on different transportation pathways. The implementation of this project will entirely obtain the satellite-based East Asian dust fluxes of emission, transportation and deposition process, which can provide important observation basis for improving the prediction accuracy of the model.

东亚地区沙尘气溶胶的跨太平洋输送是地球上最大尺度的沙尘传播过程，对地球环境、生态、天气和气候产生了深远影响。深刻理解与之关联的沙尘循环过程，对于目前以海-陆-气耦合为核心的全球气候变化研究具有重要意义。本项目拟利用A-Train卫星集群主动探测和被动遥感相补充的探测优势，辅以地基遥感探测、气象台站和再分析资料，结合HYSPLIT轨迹模拟分析，厘清不同环流背景下东亚沙尘的主要传输路径；有效区分沙尘与背景气溶胶，反演沙尘通量遥感评估所需的东亚沙尘气溶胶光学特性参数；构建适用于东亚地区沙尘排放、输送及沉降通量评估的卫星遥感反演算法，进而量化东亚沙尘的排放、输送和沉降通量；通过对比分析不同传输路径上沙尘排放、输送和沉降通量的差异，加深对东亚地区沙尘循环的理解。本项目的实施，将在厘清东亚沙尘主要传输路径的基础上，全面获取东亚沙尘排放、输送和沉降的卫星遥感资料，为提高模式预测精度提供重要的观测依据。

全面理解亚洲沙尘循环过程，有助于评估其对大气环境、人类健康、生态系统、陆地和海洋生物地球化学循环、区域及全球气候变化的深远影响。本项目结合多源观测及再分析数据，发展了亚洲沙尘质量浓度及传输通量的星载激光雷达反演算法，建成了亚洲沙尘循环卫星遥感资料集，进而从传输路径、传输通量、沙尘收支、气候影响等多个维度全面定量剖析了亚洲沙尘循环过程。主要代表性成果包括：（1）发现吸光性气溶胶（沙尘、污染沙尘、烟尘）是亚洲地区的主导气溶胶类型，这与北半球沙尘传输带及人类活动息息相关；（2）西风急流的中断以及高空槽的维持和发展，能将南亚沙尘及污染物传输至青藏高原，进而影响高原的水文循环及天气气候；（3）青藏高原及周边地区沙尘气溶胶强迫的辐射加热，能够显著影响大气热力结构，进而对高原冰雪消融产生重要影响；（4）因青藏高原及周边地形的影响，亚洲沙尘被分裂为南北两条自西向东的远距离传输路径，导致不同沙漠源向下游的最强传输高度、传输路径、以及沙尘传输贡献均存在显著差异；（5）从卫星遥感角度，第一次用观测资料证实了戈壁沙漠沙尘气溶胶对我国下游的传输贡献，显著高于塔克拉玛干沙漠；（6）远距离输送的亚洲沙尘在我国华北地区的沉积显著大于华南地区，在黄海等毗邻海域的沉积显著大于日本海和西北太平洋。项目共发表论文10篇，其中SCI期刊论文6篇，CSCD论文4篇。其中沙尘循环激光雷达反演算法发表在工程遥感类顶级期刊Remote Sensing of Environment上；南亚沙尘向青藏高原传输机理的工作发表在环境类顶级期刊Science of the Total Environment上，并被作为研究亮点推介。