Abstract

Collections of straight, RADAR-bright, linear features, or BLFs, on Saturn's moon Titan are revealed in Cassini SAR (Synthetic Aperture RADAR) images. Most are widely distributed across the northern midlatitudes SAR on SAR swaths T18, T23, T30, T64, and T83 and in swath T56 in the southern midlatitudes. To understand the origin of these features, we compare them with terrestrial yardangs in Dunhuang, China, the Altiplano/Puna of Argentina, and the Lut Desert of Iran and with a similar morphological landform, linear dunes in the Namib Sand Sea, Namibia and on Titan. We apply a statistical classification model developed through random forests, a type of decision tree classification system, grown with terrestrial and titanian training data to the BLFs. To develop the classification, we measured sinuosity, width, spacing, and length for all of the BLFs and their possible terrestrial analogs. We interpret the features in T18, T64-1, and T83 as yardangs based upon morphological similarities between them and features in Iran and Argentina, such as overall SAR brightness, straightness, and lack of branching. Similarities exist between the BLFs and terrestrial yardangs in sinuosity and spacing—sinuosity values range from 1.00 to 1.04 for all the BLFs, and terrestrial yardangs in Iran range from 1.00 to 1.001. A generated statistical model classified a large number of yardangs in T18 and T64-1. In contrast, we interpret the BLFs in T23 and T30 as stabilized linear dunes due to similarities in sinuosity, spacing, and scale with linear dunes in the Namib Sand Sea and Titan swath T3. Stabilized linear dunes may be slightly brighter than the SAR-dark dunes due a change in dielectric constant from introduction of liquids and subsequent stabilization or from the formation of a crust over the top the feature. Sinuosities range from 1.00 to 1.37 in T23 and T30 whereas dunes in the Namib and in T3 range from 1.01 to 1.05. Branching behavior similar to dunes are also observed in BLFs in swaths T23 and T30. The BLF features in T56 in the southern hemisphere we interpret to be dune-related, likely SAR-bright (rough) inter-dune areas. We base this interpretation on the presence of SAR-dark lineations between the BLFs that may be linear dunes. The statistical model classifies few yardangs in T23, T30, and T56. We conclude that statistical classification of these features can be performed. We also show that yardang orientations may aid in the development of global climate and wind models as both current and paleo wind direction indicators.

Degree

MS

College and Department

Physical and Mathematical Sciences; Geological Sciences

Rights

http://lib.byu.edu/about/copyright/

Date Submitted

2018-04-01

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd9942

Keywords

Titan, Yardangs, Linear Dunes, Cassini, RADAR

Language

english

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