Changing winds and more vegetation are probably contributing to the trend.
Among the most useful and longest-lived dust-monitoring sensors in space today is the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites. Terra MODIS has collected more than 20 years of dust data; Aqua MODIS has observed for 18 years.
“Two decades is long enough to look for meaningful trends in atmospheric dust,” said NASA atmospheric scientist Hongbin Yu. In a new study in Atmospheric Chemistry and Physics, Yu and colleagues detailed their efforts to do just that. “We looked at the world’s six major dust outflow regions. We found lots of year-to-year variability, but in most areas we did not see obvious increases or decreases in dust. The one exception was the area we defined as the northwestern Pacific. In other words, the dust that blows east from deserts in western China and Mongolia, such as the Taklamakan and Gobi deserts.”
In this area, dust activity has declined since the early 2000s. Over the course of the MODIS record, the researchers found a 1.5 percent decrease in the atmospheric dust detected by the sensor each year. “More detailed analysis showed that the trend was due to changes in the spring—March, April, and May,” said Yu. “Trends were negligible in other seasons.”
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Image via NASA Earth Observatory