| dc.description.abstract | Particulate matter (PM), which causes severe problems in human health, has become an important global issue in recent years. However, the climatology of annual variations and the interannual variations in PM concentrations have still not been fully evaluated.
In our research, we found that the vertical motion of the East Asian monsoon system can affect the development of the boundary layer height and subsequently regulate the annual variation in PM over Taiwan. By climatologically understanding the annual variation in PM, the PM pollution season in Taiwan, from October to the following April, can be delineated. Then, we further defined five phases of the PM pollution lifecycle that are similar to the well-defined East Asian summer monsoon lifecycle: onset (PM10 onset date, PMOD), active (November to January, NDJ), break (between the end of January and early February), revival (February to April, FMA) and retreat (PM10 retreat date, PMRD).
After the PM pollution lifecycle was precisely defined, the interannual variation in the PM concentration became clearer. The starting (PMODs) and ending (PMRDs) dates of the PM pollution seasons are earlier during El Niño episodes than during La Niña episodes; in particular, there is a significant 20-day difference between their starting dates. For the active phase (NDJ), climatological PM pollution development does not show distinct features under the two different El Niño-Southern Oscillation (ENSO) episodes. On the other hand, the influence of the El Niño and La Niña forcings on PM pollution during the revival phase (FMA) is significant. In summary, the climatology of PM pollution in winter is dominated by the annual seasonal cycle, but during the seasonal transition periods, October and March are significantly modulated by ENSO. In addition, our study examined the relationship between PMOD/PMRD and quasi-biennial oscillation (QBO). The results show that the QBO has no significant influence on either the PMOD or the PMRD. | en_US |