与气溶胶粒子相比,前向小角度太阳透射比值变化对卷云中的冰晶粒子更加敏感。研发了一种基于图像跟踪、自动快速变视场的太阳光度计VFOVSP,它可快速测量窄视场到宽视场太阳的透射辐射,为地基测量卷云提供了新的技术手段。介绍了仪器的系统组成与测量原理。在大气无吸收波段,将仪器VFOVSP经Langley法标定后的测量结果与POMO2的测量结果进行对比,以验证仪器测量精度的可靠性。在不同的天气条件下进行测量,结果表明:不同小角度视场下透射比值的变化与粒子的种类有关,这为区分薄卷云和气溶胶粒子提供了可能。该仪器弥补了传统太阳光度计在有云天气下实时性、单一视场探测的不足,可以较好地识别出当前大气下是否有卷云存在,能够更好地满足实际科研需求。

The forward small-angle solar transmittance ratio is more sensitive to ice crystal particles in cirrus clouds compared with aerosol particles. A photometer, named VFOVSP, is developed based on image tracking and automatic fast changing field of view, which can quickly measure transmitted radiation from narrow field of view to wide field of view of the sun. It provides a new technology for ground-based measurement of cirrus. The system composition and measurement principle of the instrument are introduced. In the atmosphere non-absorption band,after the instrument is calibrated with Langley method,the VFOVSP measurement results are compared with the measurement results of POMO2 photometer to verify the reliability of the instrument measurement accuracy. Under different weather conditions, the experimental results show that the transmission ratio at different small angle fields of view is related to the type of particles, which makes it possible to distinguish thin cirrus clouds and aerosol particles. The instrument makes up for the lack of real-time and single-field detection of traditional solar photometers in cloudy weather. It can better identify whether there is cirrus under the current atmosphere and meet actual scientific research needs.