Evaluating the meaning of “layer” in the martian north polar layered deposits and the impact on the climate connection

Compact Reconnaissance Imaging Spectrometer for Mars observations of northern Martian latitudes in summer

“…The lowest layers with sections just above the what has been called the “ Basal Unit” (BU), identified as ABrt, ABbc [ Tanaka et al , 2008] are all more water ice–rich than intermediate sections (ABb1–ABb3) as described in the next section. Future work will concentrate on determining layer sequences defined by infrared ice absorption feature strength, if these correlate with layers identified based on albedo and morphology, and if there is consistency between these spectral parameterizations and previously noted “marker” beds [ Malin and Edgett , 2001; Milkovich and Head , 2006; Fishbaugh et al , 2009].…”

“…This is demonstrated by highlighting a coherent set of points in red (Figure 11c) and then showing those same points in red on an IR false color composite (Figure 11d). This suggests that water ice content of low‐albedo “dirty” layers can be traced to intrinsic layer properties, rather than surface veneers or small patches of frost on eroded surfaces as seen in HiRISE imagery [ Herkenhoff et al , 2007; Fishbaugh et al , 2009]. Continuous horizontal banding in 1.5 μ m band depth is also seen to extend over tens of kilometers in the MSP mosaic (Figure 1).…”

Reading the climate record of the martian polar layered deposits

“…Elevations of these layer boundaries were measured on the DEM. Layer boundaries are marked by major slope breaks in topographic profiles (Fishbaugh et al, 2010b), and the elevation of each boundary were obtained from an average of measurements over $100 m along the layer boundary (Fishbaugh et al, 2010a). The thickness of marker beds could be resolved on the DEM, but only the elevation of thin layers was measured due to resolution limits.…”

“…A later analysis of visual brightness profiles found no significant cycles at similar wavelengths, but identified quasi-periodic cycles of $1.6 m within thinner layers (Perron and Huybers, 2009). Analyses of High Resolution Imaging Experiment (HiRISE) images have revealed that the visual appearance of layers is partially masked by a younger coating of dust and ice, suggesting that the relation between the visual brightness of layers and their internal composition is not simple (Herkenhoff et al, 2007;Fishbaugh et al, 2010b). Internal radar reflection layers are related to variations in dielectric properties within the NPLD, and thought to be dust rich (Phillips et al, 2008).…”

Ephemeral liquid water at the surface of the martian North Polar Residual Cap: Results of numerical modelling

“…Composition of the ice-silicate mixture. The dusty layers within the NPRC are composed of water ice and martian dust (Kieffer et al, 1976;Fishbaugh et al, 2010). Phillips et al (2008) estimated the dust component in the dusty radar-reflective layers of the Mars North Polar Deposits to be between 2% and 30%.…”