Parameterizing wet removal of aerosol-forming oxygenated gases and its regional and global impacts

Particles suspended in the atmosphere (“aerosols”) are responsible for a large fraction of global deaths and have a substantial impact on the Earth’s energy balance, but their impacts remain uncertain and difficult to model. Much of this particle mass is formed when gases emitted by natural and man-made sources undergo sunlight-driven chemistry that produces soluble and condensable compounds, forming particles. While these “aerosol-forming gases” are being chemically transformed, they are also being removed from the atmosphere by precipitation and settling to the Earth’s surface, which can have a significant effect on the formation, growth, and removal of aerosols.

aerosols

Small particles or droplets, such as wildfire smoke, volcanic gases, or salty sea spray, that float in the air. They are emitted by both natural events and human activities.

Source: NASA Global Climate Change Source

Unfortunately, the parameters that control removal of gases from the atmosphere are highly uncertain, and almost no real-world observations exist on the role of precipitation in this process. The goal of the proposed research is to use existing and new data to quantify the rates at which atmospheric gases and particles are removed by precipitation and to understand the role of precipitation in the formation of aerosols across several sites. Characteristics of precipitation and atmospheric gases and particles will be used to estimate removal of gases by precipitation at 12 globally distributed facilities in the DOE Atmospheric Radiation Measurement (ARM) network. These existing data will be combined with unique measurements collected in 2014 at the Manacapuru, Brazil ARM facility as part of the ARM GoAmazon campaign, and new measurements of precipitation and removal of gases in Blacksburg, Virginia. The major outcome of this research will be an improved understanding of the regional and global impacts of precipitation on the formation of aerosol that is informed by real-world measurements and representative of diverse geographical regions. Additional scientific advances expected from this research include new methods to calculate the removal of gases from widely available measurements, increased availability of these data, and advances in atmospheric chemistry models.