Preliminary Design And Data Analysis Of Active And Passive Combined Cloud Lidar System

In the measurement of daily meteorological service, cloud height, cloud amountand cloud form are the most basic elements of observation. With the development ofLidar technology, signal processing technology, the whole sky imaging and imageprocessing technology, the detection of meteorological elements with instruments isdeveloped rapidly. The equipments of cloud height and cloud amount detection havebeen used in meteorological measurement. However, cloud height and cloud amountare respectively recorded by the cloud Lidar and the whole sky imager independently.If you want to get the data more universal, two different devices for cloud detectionshould be emplaced in the same meteorological station generally.In this paper, we design a cloud Lidar system combined with a whole sky imager,to obtain cloud height and cloud amount at the same time measurement. First, wesimulate the light path and optical efficiency of cloud Lidar by ZEMAX and thesignal-to-noise of Lidar also be analyzed. In addition, we add the fisheye lens for adigital camera as the whole sky imager and then studied the B/R ratio thresholdsegmentation algorithm of cloud amount. Combined with profile data of cloud heightand cloud two-dimensional distribution in the sky, we make a preliminary analysis ofdata fusion for cloud amount, cloud height and cloud classification. For measuringcloud height, it’s difficult to distinguish the cloud height in haze weather. So skyimages of the whole sky imager can be used to identify the fog haze and improve thecloud base recognition accuracy. A special case is given to verify the method isfeasible. Moreover, the analysis of the whole sky image can obtain total cloud amount.With the data of cloud height, we can estimate the spatial distribution of the cloud inthe sky and achieve more accurate classification of cloud through the data fusion.