New Martian climate constraints from radar reflectivity within the north polar layered deposits. Issue 2 (21st January 2017)

• Record Type: Journal Article
• Authors: Lalich, D. E.; Holt, J. W.
• Is Part Of: Geophysical research letters. Volume 44:Issue 2(2017)
• Page Start: 657
• Page End: 664
• Publication Date: 2017-01-21
• Subjects: Mars -- polar -- radar -- cryosphere -- climate; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL071323
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The north polar layered deposits (NPLD) of Mars represent a global climate record reaching back millions of years, potentially recorded in visible layers and radar reflectors. However, little is known of the specific link between those layers, reflectors, and the global climate. To test the hypothesis that reflectors are caused by thick and indurated layers known as "marker beds, " the reflectivity of three reflectors was measured, mapped, and compared to a reflectivity model. The measured reflectivities match the model and show a strong sensitivity to layer thickness, implying that radar reflectivity may be used as a proxy for short‐term accumulation patterns and that regional climate plays a strong role in layer thickness variations. Comparisons to an orbitally forced NPLD accumulation model show a strong correlation with predicted marker bed formation, but dust content is higher than expected, implying a stronger role for dust in Mars polar climate than previously thought. Key Points: Modeling and observations show that "marker beds" are a plausible source for radar reflections Geographic reflectivity patterns correlate with long‐term accumulation patterns, so reflectivity may be a proxy for accumulation rate Comparison to an NPLD accumulation model shows that higher dust deposition rates are necessary to match observations