A study published June 1 in Nature Geoscience has used data from NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) to significantly improve the accuracy of computer models that estimate the effect of airborne mineral dust on Earth’s radiation balance.
The research found that EMIT data reduces the uncertainty in key variables by more than a factor of six, particularly regarding the role of iron oxides.
Key Findings
- A research team led by Cornell University analyzed data from NASA’s EMIT instrument, which is mounted on the International Space Station. EMIT uses high-resolution imaging spectroscopy to produce global maps of mineral composition in dry regions.
- The study focused on iron oxides (hematite and goethite), which strongly absorb solar radiation. Previously, the abundance of these minerals in dust was considered the largest source of uncertainty in dust’s radiative effects.
- By incorporating EMIT data into four independent Earth system models, the team reduced the uncertainty in radiative forcing from iron oxides from 0.62 watts per square meter (W/m²) to 0.10 W/m²—a more than sixfold improvement.
- With this reduction, other factors such as dust emission, transport, and particle size distribution now represent the primary sources of uncertainty in dust’s climate impact.
Regional Improvements
- Over the Sahara Desert, the world’s largest dust source, models using EMIT data reduced errors in simulated radiative effects by up to 80%. Those simulations aligned more closely with satellite observations.
- Across all major global dust source regions, including North Africa and the Middle East, uncertainty in dust’s radiative effects was cut by more than half.
- Regional differences in dust composition became clearer: dust originating from North Africa tends to contain more iron, enhancing solar absorption. Dust from some Asian regions has more reflective properties, potentially producing a cooling effect.
Broader Implications
- Globally, the overall effect of dust on solar radiation remains within previously estimated ranges, but confidence in those estimates has increased.
- The improved data on mineral composition allows researchers to shift focus to other factors, including how dust moves, transforms in the atmosphere, and how climate change may alter dust sources.
- More accurate dust data also supports research in areas such as ocean fertilization, the darkening of snow and ice surfaces, and cloud formation.
Next Steps
The study’s authors identified further improvements in measuring dust particle size and expanding observations in poorly studied regions as logical next steps.
Authors and Funding
The study involved researchers from Cornell University, the NASA Goddard Institute for Space Studies, the Barcelona Supercomputing Center, the Catalan Institution for Research and Advanced Studies, the Universitat Politècnica de Catalunya, the NOAA Geophysical Fluid Dynamics Laboratory, the University of Maryland Baltimore County, the NASA Jet Propulsion Laboratory, the Planetary Science Institute, the University of California, Los Angeles, and the California Institute of Technology.