Interannual variability of dust height and the dynamics of its formation over East Asia.

The vertical structure of dust layers is rarely investigated, despite its critical role in exploring the radiative and microphysical effects of dust aerosols. In this study, we primarily investigate the temporal variability of most probable dust height (MPDH) over dust source regions in East Asia and its interactions with climate parameters using CALIPSO lidar measurements under cloud-free conditions in spring from 2007 to 2018. The vertical profile of dust aerosols exhibits significant interannual variability over this time; dust is mainly concentrated below 7 km and associated with a dust occurrence frequency (DOF) of 0.6, and the DOF is much higher than that over the Sahara and West Asia. We also found that high Indian Ocean sea surface temperature (SST) significantly contributes to the transport of dust aerosols to downstream areas by changing the circulation field near the equator and in the mid-low latitudes of the Northern Hemisphere, which results in low MPDH over northern China. MPDH is significantly negatively correlated with 500-hPa westerly wind and precipitation, and is positively correlated with surface air temperature (SAT) and normalized difference vegetation index (NDVI). Furthermore, MPDH is positively correlated with the Arctic Oscillation (AO) and the Atlantic Multidecadal Oscillation (AMO), but negatively correlated with the El Niño-Southern Oscillation (ENSO). The correlation coefficient between AMO and MPDH is 0.71 after detrending, which indicates that the AMO also plays an important role in the interannual variability of MPDH over East Asia. Furthermore, the Indian Ocean SST is the main influencing factor of the interannual variability of MPDH over northern China, but zonal wind is probably only the intermediate mechanism.