[세미나] 이윤곤 교수님

Potential impacts of regional and large-scale climate variability on Asian aerosols activity: an observational investigation using ground and satellite measurements

Potential impacts of regional and large-scale climate variability on Asian aerosols activity: an observational investigation using ground and satellite measurements

Anthropogenic and natural aerosols emitted from the East Asia have received a great attention partly due to their potential impacts on environment and climate over the past decades. In today’s talk, I will introduce potential impacts of regional and large-scale climate variability on Asian aerosols activity (i.e., emissions and transports) based on an observational investigation using ground and satellite measurements. First topic: Potential impacts of northeastern Eurasian snow cover on generation of dust storms in northwestern China during spring. The effects of the northeastern Eurasian snow cover on the frequency of spring dust storms in north- western China have been examined for the period 1979–2007. Averaged over all 43 stations in northwestern China, a statistically significant relationship has been found between dust-storm frequency (DSF) and Eurasian snow water equivalent (SWE) during spring: mean DSF of 7.4 and 3.3 days for years of high and low SWE, respectively. Further analyses reveal that positive SWE anomalies enhance the meridional gradients of the lower tropospheric temperatures and geopotential heights, thereby strengthening westerly jets and zonal wind shear over northwestern China and western Inner Mongolia of China, the regions of major dust sources. The anomalous atmospheric circulation corresponding to the Eurasian SWE anomalies either reinforces or weakens atmospheric baroclinicity and cyclogenesis, according to the sign of the anomaly, to affect the spring DSF. Second topic: Springtime trans-Pacific transport of Asian pollutants characterized by the Western Pacific (WP) pattern. Springtime trans-Pacific transport of Asian air pollutants has been investigated in many ways to figure out its mechanism. Based on the Western Pacific (WP) pattern, one of climate variabilities in the Northern Hemisphere known to be associated with the pattern of atmospheric circulation over the North Pacific Ocean, in this study, we characterize the pattern of springtime trans-Pacific transport using long-term satellite measurements and reanalysis datasets. A positive WP pattern is characterized by intensification of the dipole structure between the northern Aleutian Low and the southern Pacific High over the North Pacific. To evaluate the influence of the WP pattern, we examine several cases of trans-Pacific transport reported in previous research. Interestingly, most trans-Pacific transport cases are associated with the positive WP pattern. This study reveals that the WP pattern can be utilized to diagnose the strength of air pollutant transport from East Asia to North America.