The distribution of barchan morphologies in aeolian environments
Topics:
Keywords: Barchans, Martian dunes, Wind variability, Sand source, Dune morphology
Abstract Type: Paper Abstract
Authors:
Pei Zhang, Texas A&M University
Douglas J. Sherman, The University of Alabama
,
,
,
,
,
,
,
,
Abstract
Barchan dunes are widely distributed in both terrestrial and extraterrestrial aeolian environments. The features of barchan shapes are the result of the interactions between drifting sand processes and landforms, especislly associated with dune migration driven by quasii-unidirectional winds across stable surfaces. In this research, eight shape characteristics of barchans on Earth and Mars were measured. These included samples from 30 dune fields on Earth (3686 samples) and 10 on Mars (720 samples). Three dimensionless shape metrics, i.e., width, length, and symmetry ratios, were derived from the measurements and these were used to classify barchan shapes into eight types based on the degree of elongation or compaction, symmetry of the horns, and whether the horns diverge, converge, or are relatively parallel. In general, the results show that the distributions of barchan morphologies on Earth are significantly different from those on Mars. The abundance or scarcity of barchan types in different dune fields is evaluated. One of the dune types (compact, symmetrical, divergent) is rare on Earth and Mars. Four Earth dune fields and six Mars dune fields are notable for having a dominant (>50%) barchan type. Twelve terrestrial dune fields and eight Martian dune fields have less than 5% of four or more barchan types. Two environmental control factors, wind variability and locations relative to sand seas, will be discussed in this paper. The results suggest the potential to derive driving forces from barchan morphologies and will point to the future directions for aeolian processes-landforms studies on Earth and extraterrestrial surfaces.
The distribution of barchan morphologies in aeolian environments
Category
Paper Abstract