[VIEWPOINT]Wrestling with a dust cloudYellow sand is a cloud of dust that blows out of the Chinese desert area due to the area’s low atmospheric pressure. We call it yellow sand, but its official international name is actually “Asian dust.” Yellow sand originates from various vast places, including the Taklimakan Desert of the Tarim Basin in the north of Tibet, the Gobi desert in the northern region of the Chinese city of Xian, the wide yellow-earth plateau of Inner Mongolia and the desert in northern Manchuria. The frequency and intensity of yellow sand depends on the terrestrial, climatic and atmospheric conditions of the source regions.
When the sun blazes down on the desert every spring, a strong low atmosphere pressure is created on the land, forming a whirlwind. This huge storm of dust blows for thousands of kilometers, riding a strong west wind, and creates the phenomenon we call yellow sand.
The particles of yellow sand that blow to Korea have a radius between 0.2 microns and 10 microns, but the particles with radii between 1 to 3 microns are most common in Korea. Most of the particles with a radius over 3 microns drop close to the source area. Yellow sand reduces visibility and reduces the temperature because it reflects the sun. It also provokes bronchial trouble and asthma, and is the cause of eye infections. It disrupts photosynthesis in plants, and particles with a radius of less than 1 micron interfere with the function of precision instruments and communication tools such as cell phones. There is a positive aspect of the yellow sand, in that it makes soil fertile, but the negative effects stand out more at the moment.
Recently, the frequency and intensity of yellow sand have become greater. There are three major reasons why: First, with the rapid expansion of the deserts, the source region of yellow sand is expanding to northern Manchuria. Second, climate change due to global warming accelerates the production and movement of yellow sand. Third, the effects of even light clouds of yellow sand are becoming greater because of urbanization and economic concentration.
Since the intensity of the yellow sand changes depending on the surface condition and climate of the source, as well as atmospheric movements, it is very important to observe in detail the movements of the yellow dust and predict its future courses to prevent damage. Because Korea is equipped with dust-measuring equipment, satellites and optical observation instruments and has a movement-prediction model, we have comparatively easy access to information on the source and movement route of yellow sand. However, we still lack information on its characteristics and effects.
In 1999, China, South Korea and Japan discussed ways for the three countries to cooperate to study the source of yellow sand and predict its movements. In the spring of 2001, representatives of 13 countries in the Pacific region met at an international conference held in Jeju and agreed to launch a project to monitor and track the yellow sand.
However, it is up to governments to prevent damage from yellow sand. Each branch of the government has to have a clear role and function in this process. The Korea Meteorological Administration should forecast the appearance of yellow-sand clouds, the Ministry of Environment should announce the results of analyses on the components and characteristics of yellow sand in real time, and the Ministry of Health and Welfare should be responsible for the effects it has on welfare and health. That is, it is necessary to establish a pan-governmental infrastructure for preventing a disaster caused by the yellow sand. Viewing yellow sand as an unwelcome guest that always visits in the spring or as a natural phenomenon will only result in the sand causing greater harm.
* The writer is the head of the Earth Environment Research Laboratory at the National Institute of Environmental Research.
by Oh Sung-nam