Latitude-dependent nature and physical characteristics of transverse aeolian ridges on Mars

[1] Narrow-angle images from the Mars Orbiter Camera (MOC) have revealed the common occurrence of small-scale (<100 m wavelength) bright transverse aeolian ridges (TARs) on the surface of Mars. MOC images were used to assess the broad distribution of TARs from 90 N to 90 S between 180 E and 240 E to investigate their relationship to latitude, elevation, thermal inertia, geologic units, local slopes, and surface roughness. Out of 5112 examined images from the primary mission, 520 (10%) contain evidence of TARs, 92% of the images with TARs are located between ±50 latitude, and very few occur in the middle to upper latitudes or polar regions of either hemisphere. TARs are observed at elevations from 5 km to 3 km, with the highest frequency (26%) between 1 and 0 km. There is no systematic relationship between the distribution of TARs and global thermal inertia measurements. Most TARs occur in geologic units associated with the Channel System Materials (39%) and the Olympus Mons Aureole (33%). At a length scale of 1.85 km/pixel, the average local slopes for images with and without TARs are 1.92 and 1.36 , respectively. Of the parameters investigated, the latitudinal trend of TARs in both hemispheres appears to be predominantly related to surface roughness, with a positive linear correlation between the surface roughness of geologic units and frequency of TARs (R = 0.87). Factors affecting the semiglobal distribution of TARs are likely related to the climate and wind regimes in which they formed but do not provide definitive evidence for either saltation or reptation formation mechanisms.