Approximately half of the dust particles in the atmosphere of North America, which affect both climate and air quality, has transatlantic origin, according to an article published by a group of American scientists in the journal Science.
Hongbin Yu (Hongbin Yu) from the Center of NASA Goddard and his colleagues for the first time using satellite measurements evaluated the number and composition of the dust, which each year into the atmosphere over the American continent.
They used data obtained with spectroradiometers MODIS, from satellites "Terra" and "Aqua" and CALIOP lidar on board the "Calypso". Satellite information has allowed them to build a three-dimensional picture of the migration of dust particles, aerosols, and other types of air pollution, including its data on the distribution of their height.
The results showed that each year in North America gets about 64 million tons of "overseas" dust and aerosols coming mainly (88%) from Asia across the Pacific. This is almost the same as the "home" of dust — about 69 million tons of aerosols of natural and anthropogenic origin.
Previous estimates made using different computer models, gave values of "import" of dust on 18-46% less than the satellite measurements. Scientists have estimated the contribution of "import" of dust on regional climate, and found, in particular, that it accounts for about 35% of the absorption of solar radiation in the atmosphere.
However, transatlantic dust and aerosols in composition was much less harmful to the quality of air — about 80% of the mineral dust particles, while in the "home" a significant proportion of the products of combustion and industrial processes — the particles of soot, nitrogen compounds and sulfur. In addition, most of the transatlantic dust is at a high altitude and has little effect on the near-surface air.
Scientists point out that attempts to regulate emissions of pollutants should be considered transboundary transport and new data on the extent of such transfer may be important for policy makers.
"To mitigate the impact of aerosols on climate processes in the region's efforts of one country is not enough. Entire world must work together to meet these challenges," — the scientists say.
The authors emphasize that the scope of the import of dust in America depend not so much on the development of the industry in Asia, but on the process of desertification.
"So even reducing industrial emissions in the developing countries of Asia can be easily offset by the increase in dust emissions due to changes in weather conditions and the spread of deserts," — says the article.