| Cloud is an important part of the earth-atmosphere system.Cloud plays an important role in the development and evolution of climate change and weather system through latent heat transport,precipitation and cloud radiative forcing.The microphysical structure of the cloud reflects the thermal and dynamic processes within the cloud,which is the main factor that determines the formation,development and demise of the cloud.Accurate measurement of cloud microphysical parameters and in-depth study of cloud microphysical processes are of great significance to cloud physics,climate change,numerical weather prediction,artificial weather and many other fields.In order to satisfy the needs of high precision measurement of cloud particle microphysical characteristics in the field of atmospheric science,a cloud particle measurement method based on forward scattered light imaging of particles is proposed in this paper.To apply this method to the measurement of cloud microphysical parameters,a circular light source which can be used for dark field imaging is designed.On this basis,a prototype of Cloud Particle Imaging Sensor(CPIS)which can obtain cloud particle images without touching particles is developed.The embedded software which can realize exposure control,image acquisition and processing and data transmission is programmed and debugs with prototype.A cloud particle image processing algorithm based on mathematical morphology is established to measure the particle size and shape of cloud particles.An image restoration algorithm suitable for defocus cloud particle image restoration is designed,which effectively improves the data utilization and increases the sample size.A calibration method for measuring the single pixel size and imaging depth of field of the prototype is proposed and the calibration experiments are carried out.The prototype is used to carry out observation experiments in the diffusion cloud chamber and high mountain to verify the performance of the instrument.The experimental results show that the cloud particle imaging sensor has high measurement accuracy and good environmental adaptability,and it is a kind of cloud particle in-situ detection equipment with great development potential. |
