Life on Earth is supported by a thin layer of gases held to the planet’s surface by gravity. Our atmosphere provides the breath of life and regulates global temperature in the face of a constant onslaught of solar radiation. Aerosol particles—including smoke, ash, soot, mineral dust, and sea salt—play a key role in regulating atmospheric energy exchanges. The particles can directly drive effects in the energy budget by raising the Earth’s albedo, scattering and reflecting solar radiation back into space and ultimately cooling the planet. Indirect effects of aerosols are more complex, like the uncertainties of particle interaction with clouds. A better scientific understanding of the role of aerosols in the atmosphere could give communities a vital tool to adapt to the Earth’s changing climate.
Here Lacagnina et al. evaluate the single-scattering albedo of the atmosphere with measurements from the Polarization and Anisotropy of Reflectances for Atmospheric Sciences Coupled with Observations from a Lidar (PARASOL) satellite and compare their measures with observations from the Ozone Monitoring Instrument and the ground-based Aerosol Robotic Network. This study is the first time PARASOL data have been compared alongside other observations, and the data cover almost the entire globe, offering valuable insight into aerosol influence.
The scientists found that the data sets usually reflect real-world observations quite nicely but that the models slightly overestimate aerosol scattering, as opposed to absorption. In other words, the models predicted an outsize role for aerosol, scattering solar radiation and cooling the upper atmosphere. The researchers suggest this bias implies that the direct and indirect effects of aerosols within the atmosphere may be bigger than previously simulated.
The researchers hope their work highlights the potential and the importance of aerosols and the single-scattering albedo effect in evaluating the Earth’s energy exchange. The success of this comparison between PARASOL data, observations, and model simulations may help open the door to more cohesive analyses of the atmosphere. (Journal of Geophysical Research: Atmospheres, doi:10.1002/2015JD023501, 2015)
—Lily Strelich, Freelance Writer
Citation: Strelich, L. (2015), Aerosols may play a big part in atmospheric absorption, Eos, 96, doi:10.1029/2015EO040423. Published on 2 December 2015.