珠江口咸潮入侵数值模拟中多源遥感数据的同化研究

In recent years, due to global change acceleration (sea levels rise, drought, population explosion, economic development and so on ), seawater intrusion into the Pearl River Waterway has been occurring earlier, lasting longer and involving more cities. However, the capability for seawater intrusion monitoring and early warning is relatively weak in the Pearl River Estuary due to short of observation data. During seawater intrusion, field measurements and sampling are carried out in the reaches of Pearl River Estuary, and the regression models for salinity inversion are built based on field experiments data and hyperspectral HICO, MERIS remote sensing images. The tide parameters, wind direction and wind speed, upriver discharge, river topography and salinity are analyzed, and the numerical simulation models of salinity are built based on GIS in the reaches of Pearl River Estuary. Further study on assimilation of multi-source remote sensing data into the numerical simulation models of seawater intrusion are done in the Pearl River Estuary, China. The seawater intrusion simulation models of salinity assimilation are set up using satellite-derived parameters and boundary conditions. Assimilation of multi-source remote sensing data into the numerical simulation models of seawater intrusion have potential importance for understanding evolution of saltwater intrusion process and geographic distribution of salinity, and improving the capability for seawater intrusion remote sensing monitoring and early warning by numerical simulation model in the Pearl River Estuary.

近年来，由于全球变化加速（海平面上升，干旱，经济发展等），珠江三角洲咸潮入侵出现不断加强的趋势，对珠三角城市群构成整体威胁，然而，由于观测资料不足，当前对珠江口咸潮的模拟预警能力还比较薄弱。因此本课题在咸潮入侵过程的全周期内，对珠江口主要感潮河段进行定点观测、遥感观测和常规取样，基于GIS技术构建珠江口咸潮入侵数值模拟模型，加强对咸潮发生、发展的动态演变和潮位涨落、风速风向变化关系的理解。同时，开展基于低照度HICO、MERIS多源遥感数据的河口盐度信息反演、同化和标定研究，提高珠江口盐度遥感反演信息的时空分辨率和精度。然后，进一步开展遥感反演信息和数值模拟模型的耦合研究，构建珠江口咸潮入侵数值模拟的遥感同化模型，提高咸潮预警预报的精度。本研究将遥感信息的实时性、宏观性与数值模拟模型的连续性、机理性良好结合起来，对促进珠江口咸潮遥感机理、数值模拟理论和数据同化方法的进一步发展具有重要意义。

本课题在咸潮入侵过程的全周期内，对珠江口主要感潮河段进行定点观测、遥感观测和常规取样，基于潮水参数模拟珠江口感潮河段断面面积模型，构建珠江口咸潮入侵数值模拟模型。同时，进一步开展水色三要素、水质等参数的遥感反演研究，构建了宽范围悬浮物浓度（5.8–577.2 mg/l）遥感反演的通用模型，并应用于MODIS影像；构建了基于黄色物质的盐度遥感反演模型，并应用于MERIS图像（R2=0.6，RMSE=3.62 ‰）；构建了近海透明度的半分析反演模型（R2=0.66，RMSE=0.14m）。然后，进一步开展了同化方法研究，提出了一种多尺度重采样粒子滤波算法，仿真结果表明多尺度重采样粒子滤波算法算法估计值更接近与真实值，精度更高。同时，对于同化过程中涉及的水体生物光学模型参数开展了优化研究。采用模拟退火算法同时优化了后向散射模型系数和双向反射因子，并开发了生物光学正演模型(RMSE<0.0023)。验证结果说明迭代优化的后向散射模型系数和双向反射因子能够适用于广东近岸河口生物光学参数模拟。