Tracking short-term variations in titan ’ s haze distribution

We present an analysis of the hydrocarbon haze distribution on Titan using eight months of frequent observations with SINFONI VLT. The latitudinal and temporal distribution of organic haze can be used to constrain Titan’s global circulation as well as indicate potential regions of increased organic deposition on Titan’s surface which, in the presence of liquid water from impact melt or the subsurface oceans, could be favorable for life. Preliminary results show significant latitudinal and temporal variations, suggesting a not yet understood local influence on haze production. Introduction: Titan is the only satellite in the solar system with a thick atmosphere, which is predominantly comprised of nitrogen and methane along with a photolytically-produced hydrocarbon aerosol haze. The haze distribution throughout the atmosphere is the basis for many aerosol models which work to constrain the locations of organics across Titan [1,2]. Here we present a study of the haze distribution based on analysis of spectra from SINFONI VLT in both H+K bands acquired over a year during a broader cloud monitoring campaign [3]. We analyze 56 observations over eight months which each have four 15 second exposures coadded together to cover the entire disk. We use a spherically corrected plane parallel radiative transfer (RT) model PyDISORT [4,5] to simulate Titan’s atmosphere. We are interested in understanding the seasonal distribution of hazes in Titan’s atmosphere. It has been shown through observations that winds in Titan’s atmosphere can redistributue the haze [1,6,7]. To date, variations in the structure and density of Titan’s hazes have been at a limited spectral resolution and wavelength coverage. The analysis presented here is based on simultaneous observations in the H+K bands, which more than doubles the spectral coverage used in [5]. This utilization of a broader wavelength bandpass gives a greater spectral resolution and wavelength coverage, which allows for a more accurate knowledge of the location of organics. Methods: We generate synthetic spectra based upon in situ observations from the Huygen’s probe [8,9] and ground based veiwing geometries with our RT model. Our mod el is split into 20 layers, where each layer has its own characteristics such as altitude, pressure, temperature, methane opacity, and haze opacity. The model is a DISORT plane parallel solver implemented in Python that includes properties such as multiple scattering for phase functions, layers, and altitudes, to accurately simulate Titan’s atmosphere. In this work we cover regions that correspond to a μ > 0.65, where μ is the cosine of the incident or emission angle (note that these are approximately equal as the phase angles of ground based observations are small). This restriction is due to the RT model’s limitations near the limb. We calculate the incidence, emission, and phase angles (as inputs for the RT) for each pixel using the JPL ephemeris, and then implement the described cutoff to determine which pixels will be analyzed.