Christa Hasenkopf

Determining and comparing the optical properties of laboratory analogs of Titan and early Earth organic hazes

An organic haze layer, similar to the thick haze currently enveloping Titan, may have formed on early Earth. This haze could have had profound effects on the early Earth climate and the life existing and evolving on it. Climate models of early Earth that include this organic haze have had to rely on optical properties of Titan's haze. However, unlike Titan haze, early Earth organic haze likely formed in an atmosphere containing CO2 in addition to CH4 and N2. The presence of CO2 causes oxygen-incorporation into the haze aerosol. We investigate the differences in the chemical and optical properties between Titan and early Earth haze laboratory analogs that this oxygen-incorporation induces via the novel technique of cavity ring-down aerosol extinction spectroscopy at λ = 532nm. This technique allows the extinction of size-selected aerosols to be measured "on the fly," which is unprecedented for Titan or early Earth haze laboratory analog studies. Using the measured extinction values and applying Mie theory, we have estimates of the total refractive index at λ = 532nm for a Titan haze analog and compare our results to other workers who have used thin-film techniques. Studies of early Earth organic haze are ongoing, and we are expanding our setup to include λ = 355nm and 1064nm CRD cells. These experiments provide essential data for modeling early Earth's climate and understanding the conditions that early life experienced.

See: http://atoc.colorado.edu/~hasenkop/research.html for more information.

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