Ground-based network observation of Asian dust events of April 1998 in east Asia

We coordinated a ground-based network that has been in use since 1997 to ob serve Asian dust during springtime. Huge Asian dust events that occurred in the middle of April 1998 were captured by this network. In this paper we p resent the organization of the network; a description of the instruments, i ncluding the lidar, sky radiometer, and optical particle counter; and the r esults of the observation, and offer discussions regarding the transport me chanism of Asian dust in east Asia using an on-line tracer model. We discus sed the time series of the surface concentration and the height distributio n of the dust. A cutoff cyclone generated during the dust episode was respo nsible for trapping and sedimentation during the transportation of the Asia n dust, particularly in the southern parts of China and Japan. Horizontal d ust images derived from NOAA/AVHRR clearly revealed the structure of the vo rtex. The lidar network observation confirmed the general pattern of dust h eight distribution in this event; the height of the major dust layer was ab out 3 km over Japan but was higher (4 to 5 km) in Seoul and Hefei. A thin d ust layer in the upper troposphere was also commonly observed in Hefei and Japan. Evidence of the coexistence of dust and cirrus was shown by the pola rization lidar. The lidar network observation of Asian dust and satellite r emote sensing provide key information for the study of the transport mechan ism of Asian dust. Further extension of the lidar network toward the interi or of the continent and the Pacific Rim would reveal the greater global mec hanism of the transportation.