The impact of channel effect on Asian dust transport dynamics: a case in southeastern Asia

Abstract

A super heavy dust event was identified with unprecedented PM₁₀ in terms of speed and concentration in the southeastern Asia. The average concentration was observed exceeding the value of 1000 μg m⁻³ for the duration lasting more than 10 h, with the highest value reached 1724 μg m⁻³ in northern Taiwan on 21 March 2010. We found that this case exhibited an uneven and intriguing spatial distribution of PM₁₀ concentration and transport speed between eastern and western Taiwan. Higher values were observed in the western and northern areas. The peak concentrations can vary up to 5-fold between western and eastern Taiwan, and ten-fold between the northern tip and southern tip of Taiwan, only about 400 km apart. A high resolution, 10 km, numerical study by Weather Research Forecast (WRF) and WRF-chem models revealed that this intriguing spatial distribution of the Asian dust transport was resulting from a strong coupling effect of the geographic channel effect and blocking of the easterly from the Pacific Ocean. We are confident that this coupling effect can be revealed only by applying a high resolution numerical study in other similar regions.