Dual-site lidar observations and satellite data analysis for regional cloud characterization

Lidar data observed by two continuously operated portable automated lidar (PAL) systems and images from the visible and thermal infrared channels of the advanced very high resolution radiometer (AVHRR) sensor on board the NOAA 16 satellite are employed for the characterization of cloud heights and cloud types. The PAL systems are located in Chiba and Ichihara city areas, separated by approximately 10km. Measurements from October 2003 to March 2005 reveal that monthly averages of cloud base height and cloud cover ratio show good agreement between the two sites. The characteristics of the vertical (Chiba) and slant (Ichihara) measurements are also discussed. The PAL data are used to adjust threshold values of a cloud-type classification method in split-window data of NOAA 16-AVHRR. Comparisons between the lidar signals and the cloud classification results from the concurrent AVHRR images show that the classification method can reasonably be applied to this mid-latitude case, although the split-window technique was originally developed for tropical clouds. (c) 2007 The Optical Society of Japan.