Characterizing the transport pathways of Asian dust

Abstract

Backward trajectories, synoptic analyses, and regional dust models are applied to analyze the aerosol particles obtained from aircraft measurements during major dust events in the Asian Pacific Regional Aerosol Characterization Experiment (ACE‐Asia) to understand the controlling mechanism of Asian dust transport. The selected high concentrations of aerosol measurements are traced back to their source areas, and the summarized eleven representative trajectories of dust particles are categorized into three types, including the upper‐level (U type), lower‐level (L type), and descending (D type) transport. The characteristics of the dust transport during different stages for each of the three types are inspected. It is found that the transport distance of a dust event strongly depended on the source areas relative to the synoptic conditions. For source areas ahead of a trough, the dust particles can be uplifted into the free troposphere. If the uplifted dust particles move to the ascending areas of a trough or ascend due to other processes in the later stage, then the dust particles likely travel longer distances. When dust particles ascend in an area too close to the trough, their subsidence may be expected as sinking motion could occur after trough passage, and thus the transport distance is limited. Uplifted dust particles are typically found at a height of 400–700 hPa (2–4.5 km above ground level) over source regions. For dust particles that are generated behind a trough, the vertical motion is limited to a layer around 700 hPa, and the transport distance is also shorter.

Dust storms come to Central and Southwestern China, too: implications from a major dust event in Chongqing

“…In general, the persistent low-level transport of air by the frontal systems here showed the same pattern as one of the dominant Asian dust pathways classified by a recent synoptic study (Tsai et al, 2008). Dust was generated by the surface front between a low and an intense high over the western Gobi desert, and since its location was behind a trough at 700 hPa (not shown), the rising motion was inhibited, and the dust was transported downwind to the near-surface layer under descending or neutral flow conditions (Tsai et al, 2008).…”

“…For instance, lidar measurements from 2006-2007 showed high dust aerosol during spring , while for the ADEs of 13-14 April 2001 and 16 April 2006, modeled dust plumes also covered much of this region (McKendry et al, 2008;Tsai et al, 2008). However, no ADEs were reported in Chongqing during those periods.…”

“…Transport pathways of Asian dust are regulated by meteorology and terrain (Tsai et al, 2008). For most deserts in East Asia, frontal incursions from the northwest accompanied by upper-tropospheric troughs are the dominant mechanism for mobilizing the dust, which can then be carried above or below 3 km to downwind regions of different distance, depending on the particular synoptic systems present (Sun et al, 2001;Tsai et al, 2008).…”

“…Dust was generated by the surface front between a low and an intense high over the western Gobi desert, and since its location was behind a trough at 700 hPa (not shown), the rising motion was inhibited, and the dust was transported downwind to the near-surface layer under descending or neutral flow conditions (Tsai et al, 2008).…”

The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

“…Additionally, the longrange transport of African dust occurs primarily in the lowaltitude Saharan Air Layer (SAL) described by Karyampudi et al (1999), while the long-range transport of Asian dust can be both low-and high-altitude (<3 km and >5 km, respectively), depending critically on the relative location of dust emitting regions and synoptic scale weather systems, as shown by Tsai et al (2008). Asian dust sources are preconditioned to reach higher regions of the troposphere by virtue of their higher elevation, which makes their surface potential temperature (∼310-320 K) comparable to that of the much hotter, but nearly sea-level-based African dust emitting regions.…”