Synoptic Situation of 28-31 October 2017 Severe Dust Storm over Iraq

The phenomenon of dust storms occurs in areas that are characterized by drought, and lack of rainfalls. There are many such areas around the world, including the Middle East in general and large parts of Iraq in particular. In the last week of October 2017, a severe dust storm occurred over Iraq and lasted for four days, the aim of this work was to investigate the synoptic situation of this severe storm using remote sensing data. Data include daily true-color images, Aerosols Index (AI), surface weather maps, and 850 Mb weather maps. These data were analyzed for the four days of the storm (28-31 Oct 2017). The results showed that the storm was triggered on the 28th of October over the northwestern part of Iraq. The weather maps revealed that the cause, development, and transport of this storm were caused by a low-pressure system. This system was developed just over the source area of dust on the first day of the storm, and two ridges in which one has existed over the north of Iran and the second advanced from Egypt during the second day of the storm. The pattern of the trough and two ridges on the second and third day caused the storm to halt over central and southwestern areas of Iraq and the northern border of Saudi Arabia with Iraq. On the fourth day, the storm was moved by the northwesterly wind towards the south of Iraq and Kuwait.

Dust Heterogeneous Reactions during Long-Range Transport of a Severe Dust Storm in May 2017 over East Asia

Dust aerosol has important climate and environmental effects, which could be changed by internally mixing with anthropogenic aerosol as a result of heterogeneous reactions; however, the importance of these reactions is not fully understood yet. In this study, synergetic observations and an air quality model were used to analyze the transport of a severe dust storm and its impacts on nitrate and sulfate levels over East Asia between 3 and 11 May 2017. The model successfully reproduced the occurrence and transport of the dust storm compared to dust RGB imageries of the Himawari-8 satellite and dust extinction coefficients observed by LIDAR. The model also reasonably simulated the variations of observed nitrate and sulfate concentrations, and the results indicated that the dust heterogeneous reactions were dominant pathways for nitrate formation, but they had limited contribution for sulfate in both fine and coarse mode in Fukuoka, Japan. Dust nitrate formed rapidly after leaving China, and the highest period-averaged concentration of dust nitrate (>5 μg m−3) was shown over the Yellow Sea. Based on model results; we found that the mass ratio of dust nitrate to dust aerosol could reach 10% over the Pacific Ocean. Our results confirmed the importance of heterogeneous reactions on compositions of dust particles.