On December 12, 2022, waves of sand and dust streamed over northern China, degrading air quality in several cities.
Airborne particulate matter from the storm created hazardous air conditions in Beijing and surrounding areas. At the U.S. Embassy in Beijing, the air quality index for fine particulate matter (PM2.5) exceeded 300, which is considered hazardous to human health. Air quality measurements by the Beijing Environmental Protection Monitoring Center for PM10 (larger particles) reached 999—the maximum threshold for the indicator. Beijing residents were warned to stay inside, according to news reports.
These images were acquired on December 12, 2022, with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. The false-color image on the left incorporates infrared wavelengths to help distinguish between clouds (shown in white), snow (blue), and sand and dust (brown). The natural-color image on the right shows plumes of sand and dust from the Gobi Desert spanning parts of Hebei, Shanxi, Liáoníng, and Jílín provinces.
Spring sandstorms are common in northern China. But winter sandstorms are relatively rare, according to Zhibo Zhang, who grew up in Jílín province and now leads the Aerosol, Cloud, Radiation-Observation, and Simulation (ACROS) group at the University of Maryland, Baltimore County. “The months of March and April are really dry in this part of China, and winds due to cyclones contribute to more frequent dust storms in the spring,” Zhang said. “Although, it’s not unheard of to have sandstorms in December.”
According to the China Weather Network, the most recent December dust warning issued for Beijing was in 2015.
In 2021, Zhang co-authored an analysis of 15 years of data collected with MODIS, and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on CALIPSO, to produce a global dataset of monthly dust activity. The study found a significant reduction of dust in northern China. Zhang thinks the reduction is likely due to increases in vegetated area and more abundant precipitation in the region.
Over the last few decades, China has been restoring vegetation cover in Inner Mongolia to reduce air pollution and desertification in the region, noted Zhang. These findings align with a 2019 study that used MODIS data to show that China has substantially increased vegetation cover since 2000, in large part as a result of programs to conserve and expand forests.
NASA Earth Observatory images by Lauren Dauphin, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Emily Cassidy.