星载对地观测偏振传感器及其大气遥感应用

偏振反映电磁波的方向特性,是除强度之外电磁波的另一维度的信息。在电磁波与大气颗粒物的相互作用中,偏振由于其对颗粒物物理特征的高敏感性,可以有效提高卫星遥感探测的丰度和精度,改善对大气中特性复杂的气溶胶和云等成分的探测能力。首次综合介绍了我国研制的4种类型星载对地观测偏振传感器,包括多角度偏振相机、推扫式偏振成像仪、摆扫式偏振仪、多通道偏振辐射计,并分析了代表性的国产偏振传感器的指标参数,总结了各类载荷的探测能力。在此基础上,介绍了星载偏振传感器的主要定标方法,包括发射前实验室定标、星上定标和在轨定标。偏振载荷具有增加卫星观测维度和精度、对大气颗粒物粒径和形状特征敏感、改善弱信号探测等方面的综合优势,能够获取全球范围内高精度的大气气溶胶和云参数。星载对地观测偏振传感器具有广阔的大气遥感应用空间和潜力,可在细颗粒物PM2.5卫星遥感、关键气候因子观测及评估、极端环境事件监测、气溶胶生态效应评估、对地观测高精度大气校正等多个领域发挥作用。

Polarimetric Satellite Sensors for Earth Observation and Applications in Atmospheric Remote Sensing

Polarization that reflects the directional characteristics of electromagnetic wave, provides unique information of electromagnetic wave other than intensity. In the interactions between electromagnetic wave and atmospheric particles, polarimetry is able to effectively improve the abundance and accuracy of satellite remote sensing observation, thanks to its high sensitivities to the physical properties of particles. And polarization can significantly enhance the detection capability of the complicated atmospheric components, such as cloud and aerosol. For the first time, four types of polarimetric satellite sensor were introduced for earth observation, including directional polarimetric camera, push-broom polarimetric imager, whisk-broom polarimetric imager and multi-channel polarimetric radiometer. The related and representative Chinese polarimetric sensors are listed, with their characteristic parameters introduced and detection abilities analyzed. Then, typical calibration methods of polarimetric satellite sensors are introduced, including pre-launch laboratory calibration, onboard calibration and in-orbit calibration. Given the advantages of extra observing dimension and accuracy, high sensitivity to particulate size and shape, and enhancement on retrieving weak atmospheric signal, polarimetric satellite sensors have the abilities to obtain comprehensive and accurate aerosol and cloud parameters over the earth. These spaceborne polarimetric sensors have broad application opportunities and enormous potentials in the fields of atmospheric remote sensing, including monitoring atmospheric fine particulate matters PM2.5, observation and retrieval of essential climate variables, monitoring and assessment of extreme environmental events, evaluation of aerosol ecological effects and high-precision atmospheric correction for earth observation.