Distribution characteristics and air-quality effect of intercontinental transport dust: An unexpected dust storm case study in China

An unexpected dust storm swept throughout China from April 9 to 16, 2023. Many studies have explored the characteristics of the weather system process during this case. However, the distribution characteristics and air-quality effect of this dust storm have been less discussed, especially for the sources of dust. Here, the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) model along with MODIS satellite observations, ERA5 reanalysis data and the HYSPLIT backward trajectory model was used to analyze the transport characteristics and the contributions of dust from different sources during the period of this dust storm. The results showed that dust emissions from North Africa (NA) and the Middle East (ME), aided by atmospheric circulation patterns that facilitate long-range dust transport, collectively led to an increase in dust influx into East Asia (EA). A low-pressure system's eastward journey, starting from NA, passing through ME, and eventually reaching EA, along with the prevailing westerly winds, played a crucial role in this process.

During long-range transport, dust originating from NA and ME was typically split into northern and southern branches by the Tibetan Plateau (TP), with the northern branch being predominant. The dust primarily entered EA through the upper troposphere, where the contribution of local dust from EA tended to diminish. Evenly, ME dust was increasingly becoming the dominant source in South China. Despite this, the air quality below 500 hPa in North and 700 hPa in South China was primarily influenced by EA dust. In contrast, dust transported over long distances from ME and NA tended to rise to higher altitudes, thereby impacting PM₁₀ concentrations and air quality in upper layers. This research offered novel insights into the significant role of long-range transported dust during a single dust event in EA.