Constraining the Vertical Abundances of Haze and Methane on Titan

Saturn’s largest moon, Titan, hosts a substantial atmosphere rich with complex chemistry. While its constituents are predominantly nitrogen and methane, Titan’s upper atmosphere receives abundant UV radiation. This results in the photolysis of methane into higher order hydrocarbons that are subsequently processed to form a complex aerosol distribution on Titan. In order to better constrain the vertical abundances and compositions of these hazes, we conducted a series of disk-integrated observations of Titan with the Lowell Discovery Telescope (LDT). Observations with the EXtreme PREcision Spectrometer (EXPRES) captured not only broadband spectral slopes set by absorption of UV and visible light by aerosols in Titan’s upper and middle atmosphere, but also very high spectral resolution absorption features. One example is the ability to measure the slope, shape, and strength of the 620nm methane absorption feature, which will allow for sensitive constraints on the vertical distribution of methane in Titan’s atmosphere. To complement these observations, we also used the Near-Infrared High-Throughput Spectrograph (NIHTS) on LDT to study four methane windows (0.938, 1.1, 1.3, and 1.6-μm) that can see all the way down to Titan’s surface. This alloweds us to obtain and analyze vertical abundances of methane and hazes through Titan’s entire atmosphere. By studying both broadband and narrow features from EXPRES in conjunction with precise methane windows from NIHTS, we will be able to address ongoing science questions regarding Titan’s atmospheric chemistry. In particular, we will present our observations of longitudinal variations in Titan’s haze distribution and abundances by comparing observed spectra centered on various longitudes across Titan.