Dust Storms are an Indication of an Unhealthy Environment in East Asia

Dust storms frequently occur in Mongolia and in northern China. Each year there are 30 to 120 dusty days in source regions of Mongolia and 14–20 dusty days on the Korean Peninsula. Intense sand storms and associated dust falls produce environmental impacts in East Asia. This paper discusses the environmental degradation in Mongolia and the social, economic and atmospheric impacts of dust storms in the sink area. The impact of dust storms on environmental compartments as well as their direct and indirect consequences to basic resources like water and energy demand and supply is explained. Governments are encouraged to take appropriate action in specified regions. For monitoring dust storms there is a need for international cooperation to combat growing environmental and human security concerns.     

Discriminate Analysis for Dust Storm Prediction in the Gobi and Steppe Regions in Mongolia

A discriminate analysis method for probability forecast of dust storms in Mongolia has been developed. The prediction method uses data recorded at 23 meteorological stations in the Gobi and steppe regions of Mongolia, including surface air pressure and geo-potential height at the 500-hPa level on grid points, and weather maps from 1975 to 1990. Weather elements such as air temperature, pressure, geo-potential height etc, which influence the formation of dust storms, are prepared as predictors. To select the most informative/important predictors (variables), we used a mean correlation matrix of variables together with the Mahalonobis distance, and correlation coefficients between dust storms and predictors with an orthogonalization for removing correlated predictors. The most informative predictors for dust storm prediction are intensities of surface cyclones and migratory anticyclones, passage of cold fronts, the horizontal gradients of the surface air pressure in the cold frontal zone, cyclonic circulations from the ground surface up to the 500-hPa level, the geo-potential height at 500-hPa level and its temporal changes. Selected predictors are used in discriminate analysis for formulating dust storm prediction equations. Sandstorm data have been classified into three classes, viz., strong, moderate and weak dust storms, depending on their intensities, durations and areas covered. Predictions of the probabilities of dust storm occurrence use the prediction equations for each class. The prediction is made from 12 hours to 36 hours. Verification of the probability forecasts of dust storms is also shown. The accuracy of forecasts is 72.2–79.9% with the data used for developing equations (dependent variables), in contrast to 67.1–72.0% with unrelated data for deriving equations (independent variables).     

2005年-2008年亚洲东部沙尘暴的定期数字记录监测

地处亚洲东部的中国长春,蒙古乌兰巴托和日本鹿儿岛,作为亚洲沙尘暴的地面监测站点,用数码相机全自动定时拍摄记录天空的数字照片,通过分析数字照片数据上像素点的信息和建筑的能见度,来判断沙尘暴事件的发生及强度。对比分析了2005年-2008年冬春季节数字监测数据与NOAA,MT-SAT和Terra,Aqua/MOD IS的卫星遥感图片以及其他相关沙尘天气的报道。在监测的图片数据上,持续1-2天的强沙尘暴天气能够被清楚的识别,轻度的沙尘天气与云量较多的天气较难区别。     

On East Asian Sand and Duststorms and Associated Significant Dustfall Observed from January to May 2001

Monitoring of dust pollution at the western shore of Tae-ahn Peninsula (TAP) and in the Chongju area of central Korea was carried out from January to May 2001. It was found that in Koreathere were 9 cases of sand and duststorms (DS) and 16 associatedsignificant dustfall (SD) days. Observed maximum concentrations of DS and SD coming from NW China and Mongolia were in the rangeof 300–920 for TSP, 200–690 for PM₁₀ and 100–170 g m^-3 for PM_2.5.Satellite measurements clearly showed the formation and subsequent movement of DS to the Korean Peninsula and onward to the Korea East Sea, Japan and the Gulf of Alaska. According to satellite image analysis of dust clouds there were abundant coarse particles, measuring in size of 11.0 m. Medium-sizedparticles measuring in the range of 3.5–7.0 were also prevalent,while fine particles of less than 2.0 m were less distinctive in reflectivity. Measured values of PM_2.5 were alsorelatively low with SD events.The measured average pH values of dusty precipitation associatedwith DS were 7.24. Alkaline precipitation can play a `temporary'role in the neutralization of acidified soil until the subsequentevent of acidic rain. The new selection criteria of SD days from PM_2.5 at 85 g m^-3, PM₁₀ 190 g m^-3 and TSP 250 g m^-3 are recommended on dust pollution occurring from the invasion of a DS elsewhere.     

Observations of Dust-Storms in China, Mongolia and Associated Dust Falls in Korea in Spring 2003

A joint monitoring of dust-storms that occurred in East Asia from March until May 2003 has been carried. Our discussions include dust-storm observations in the source areas of China and Mongolia, and measurements with satellites and ground monitors in central Korea. Differences were found in the definition and measurement of dust-storms. Over the source area of Mongolia there were 6 dusty days in March, 18 days in April, and 10 dusty days in May. In Inner Mongolia of northern China there were 4 dust-storms with 14 dusty days observed over the three months. In central Korea, a sink area, there were 4 cases of weak dust-storm and 17 dusty days in the spring of 2003. The highest PM10 value was 607 μgm⁻³ and PM 2.3 was 149 μgm⁻³, respectively. These observations identify the growing need for further universal observation practices and dust-storm reporting in future. Observations indicated that snow covered the central part of the Gobi Desert, near the boundary of China and Mongolia, from December until mid-March. This is in contrast to other years when the Gobi was relatively wet, producing unfavourable conditions for the formation of intense dust-storms. In addition, the very strong winds associated with intense cyclones and anticyclones were not apparent and the systems shifted northward during the spring. As a result, the frequency and intensity of observed dust-storms in 2003 in this region were very low. This confirms that there is variability in the frequency of dust-storm formation due to the current process of desertification and climate change.     

On Sand and Duststorms and Associated Significant Dustfall Observed in Chongju-Chongwon,Korea during 1997–2000

Monitoring of the occurrence of sandstorms and dustfallphenomena from 1997 to 2000 was carried out. We refer tosandstorms, duststorms and blowing sand as the phenomenaoccurring in the source region, while significant dustfall is thephenomenon that occur in the sink area. It was noted that while the sandstorms in deserts and loess in NW-N China and Mongolia occurred any time during the year while severe sandstorms occurred frequently from March to May after the springthaw. The wind erosion in the source region usually occurred withwind speeds greater than 8 ms^-1. However, severe sandstorm phenomenon occurred with wind greater than 15 ms^-1 for at least 3 hr or more. In the source regions, sandstorms occurred over60–120 days per year. In Mongolia, the observation of thenumber of sandstorm days decreased due to the increase in rainy days.When a dust cloud from a desert reached the sink region,significant dustfall in the Korean Peninsula occurred due tothe lack of strong winds. We defined the episode ofsignificant dustfall (SD) with the following values: TSP250, PM₁₀ 190 g m^-3 and visibility 6.5 km or less. In Korea, 8–12 episodes of SD occurred per yearwith 12 to 22 SD days. The maximum concentrations of TSP recorded were 989–1396 g m^-3 with PM₁₀ values of 861–996 g m^-3 and with the lowestvisibility of 1.4–1.6 km.