[AAS08-15] UTLS aerosol measurements over Japan within eastward shedding vortices coming from the Asian summer monsoon anticyclone
Keywords:Asian summer monsoon anticyclone, aerosols , eastward shedding vortices
We found several events of enhanced particle signals at Tsukuba at 16~17.5 km (at or above the tropopause) during August-September 2018, with averaged backscattering ratio of ~1.10 and particle depolarization of ~5%. Each event had a time scale of a few days. During the same period, we observed similar enhanced particle signals at Fukuoka as well.
Backward trajectory calculations from these two sites, starting on the days with enhanced particle signals observed and on the days without separately, showed tendency that the former airmass came more from the region within the anticyclone while the latter came more from the edge regions.
The particle characteristics obtained from the lidar measurements are consistent with the solid ammonium nitrate (NH4NO3) particles from the ASM anticyclone as suggested by Hoepfner et al. (2019). But, there still is a possibility that particles originated from Ambae/Aoba Island in Vanuatu (15.389S, 167.835E) which erupted during 11-17 July 2018 are mixed in the airmass.