Influence of Dynamic and Thermal Forcing on the Meridional Transport of Taklimakan Desert Dust in Spring and Summer

Abstract

The Weather Research and Forecasting Model coupled with chemistry (WRF-Chem) associated with in situ measurements and satellite retrievals was used to investigate the meridional transport of Taklimakan Desert (TD) dust, especially in summer. Both satellite observations and simulations reveal that TD dust particles accumulate over the Tibetan Plateau (TP) and the Tianshan Mountains in summer, resulting in higher dust concentration up to 85 ?g m?3 here. The proportions of meridional transport of TD dust in summer increase up to 30% of the total output dust over the TD. Further, the impacts of thermal and dynamic forcing on the meridional transport of TD dust to the TP and Tianshan Mountains are investigated based on composite analysis and numerical modeling. It is found that the weakness of the westerly jet over East Asia significantly decreases the eastward transport of TD dust. More TD dust particles lifted to higher altitude reach up to 8 km induced by the enhanced sensible heating in summer. Under the influence of the northerly airflow over the TD regions, the TD dust particles are strengthened southward and transported to the northern slope of the TP through topographic forcing. Moreover, the cyclonic circulation raises dust particles to higher altitude over the TP. It can further intensify the TP heat source by direct radiative forcing of dust aerosols, which may have a positive feedback to the southward transport of TD dust. This research provides confidence for the investigation of the role of TP dust with regard to the radiation balance and hydrological cycle over East Asia.