Hu Shuzhen, Ma Shuqing, Tao Fa, et al. Ground-based dual-band cloud observing system and its comparative experiments. J Appl Meteor Sci, 2012, 23(4): 441-450.
Citation: Hu Shuzhen, Ma Shuqing, Tao Fa, et al. Ground-based dual-band cloud observing system and its comparative experiments. J Appl Meteor Sci, 2012, 23(4): 441-450.

Ground-based Dual-band Cloud Observing System and Its Comparative Experiments

  • Received Date: 2011-10-25
  • Rev Recd Date: 2012-04-13
  • Publish Date: 2012-08-31
  • Clouds affect the energy balance of the earth by means of absorbing and scattering radiation, and they have influences on global climate. Precipitation of clouds is the most familiar way for the earth water circulation. In the macroscopic parameters of clouds, cloud cover and cloud base height are the primary elements in the observation of clouds, where the cloud base height condition determines cloud classification and precipitation probability. However, artificial visual observation is the main method used in China at present, which are not objective and waste a mass of work force. Therefore, the research and development of an automatic measuring cloud device is extremely necessary.A ground-based cloud observing system consists of an infrared temperature measuring sensor and a double location digital ceilometer. The double location digital ceilometer calculates the cloud height of zenith by geometry method at regular time, and the infrared temperature measuring sensor acquires brightness temperature of atmospheric radiation in real time. Based on the different characteristics of visible and infrared cloud images, the height of clouds is derived and tested by the double location digital ceilometer, combined with real-time observation of zenith single-point infrared brightness temperature and ground environmental parameters. The influence of sub cloud air from ground to clouds bottom on infrared brightness temperature is analyzed, showing the feasibility of cloud base height remote sensing by ground-based sky infrared brightness temperature. The result shows that for low and middle clouds, the sky radiation brightness temperature of ground-based observation is relatively sensitive to the variation of cloud base height, therefore it can be used to estimate cloud base height. On the basis of decreasing principle of tropospheric vertical temperature, the temperature decreasing gradient parameter K from cloud base to the ground is defined and according to the decreasing gradient parameter inverse the cloud height of zenith direction. The algorithm does not depend on the air sounding data, and the formula of cloud base height is derived in practice. Double location digital ceilometer can measure a cloud height only when the bottom of the cloud has texture, and then K can be calculated, therefore the double location digital ceilometer is a calibration device in the ground-based measuring cloud system.Experimental observation has been performed using dual-band cloud observation system in the synthesize experiment base of CMA Meteorological Observation Center since July 2010, and cloud height data of the zenith is acquired each minute. Through the comparative data analysis with Vaisala CL31, ground-based dual-band cloud observation systems can provide results with high accuracy.
  • Fig. 1  Dual-band measurements of the cloud system

    Fig. 2  Zenith point infrared brightness temperature change with time

    Fig. 3  Relations between Tb in zenith direction and surface environmental parameters in clear sky condition

    Fig. 4  Relations between Tb in zenith direction and surface humidity in different surface temperature (a), relations between surface temperature and fitting coefficient slope (b) with intercept (c)

    Fig. 5  Relations between the range of surface visibility and modified temperature

    Fig. 6  Balloons measured temperature and altitude profile of Beijing Weather Observatory in Mar 2011

    Fig. 7  Balloons measured temperature and altitude profile (a), humidity and altitude profile (b) on 0700 BT 19 Mar 2011 and time series of Beijing Weather Observatory zenith point infrared brightness temperature (c)

    Fig. 8  The histogram of K

    Fig. 9  Comparison of cloud base height derived from Tb and observed by CL31

    Fig. 10  The percentage relative error of cloud base height derived from Tb and observed by CL31

    Fig. 11  Scattered plot of cloud base height from December 2010 to April 2011

    Table  1  The sky infrared brightness temperature calculated in clear sky conditions with constant ground temperature and different humidity

    DownLoad: Download CSV
  • [1]
    刘健, 张里阳.气象卫星高空间分辨率数据的云量计算与检验.应用气象学报, 2011, 22(1):35-45. doi:  10.11898/1001-7313.20110104
    高太长, 刘磊, 赵世军.等.全天空测云技术现状及进展.应用气象学报, 2010, 21(1):101-109. doi:  10.11898/1001-7313.20100114
    Shields J E, Karr M E, Tooman T P, et al. The Whole Sky imager-A Year of Progress. Eighth Atmospheric Radiation Measurement Science Team Meeting, 1998.
    Long C N, Slater D W, Tooman T. Total Sky Imager Model 880 Status and Testing Results. ARM Technical Report ARM TR-006, US Department of Energy, Washington DC, 2001.
    王青梅, 张以谟, 刘铁根, 等.一种便携式激光测云仪的云底高度反演算法.强激光与粒子束, 2005, 17(9):1312-1316.
    Genkova I, Long C N, Besnard T, et al. Assessing Cloud Spatial and Vertical Distribution with Infrared Cloud Analyzer. Fourteenth ARM Science Team Meeting Proceedings, Albuquerque, New Mex, co, Mar 22-26, 2004.
    霍娟, 吕达仁.全天空数字相机观测云量的初步研究.南京气象学院学报, 2002, 25(2):242-246.
    章文星, 吕达仁, 常有礼.地基热红外亮温遥感云底高度可行性的模拟研究.地球物理学报, 2007, 50(2):354-363.
    郄秀书, 吕达仁, 陈洪滨, 等.大气探测高技术及应用研究进展.大气科学, 2008, 32(4):867-881.
    孙学金.云的地基全天空红外遥感研究.北京:北京大学物理学院大气科学系, 2009.
    孙学金, 刘磊, 高太长, 等.基于模糊纹理光谱的全天空红外图像云分类.应用气象学报, 2009, 20(2):157-163. doi:  10.11898/1001-7313.20090204
    谭涌波, 陶善昌, 吕伟涛, 等.双站数字摄像测量云高.应用气象学报, 2005, 16(5):629-637. doi:  10.11898/1001-7313.20050509
    Liou K N. 大气辐射导论. 郭彩丽, 周诗健, 译. 北京: 气象出版社, 2004: 122-127.
    盛裴轩, 毛节泰, 李建国.大气物理学.北京:北京大学出版社, 2003:11-15;48-49.
    张玲, 张小平, 葛凡.借用探空数据校对云高的分析.科技资讯, 2009, 1:42-44. doi:  10.3969/j.issn.1672-3791.2009.01.033
  • 加载中
  • -->


    Figures(11)  / Tables(1)

    Article views (3221) PDF downloads(1452) Cited by()
    • Received : 2011-10-25
    • Accepted : 2012-04-13
    • Published : 2012-08-31


    DownLoad:  Full-Size Img  PowerPoint