Global Mapping of terrestrial wind streaks and their interpretation with climatic models

Aviv Lee Cohen-Zada, Shimrit Maman, Dan G. Blumberg
Ben-Gurion University of the Negev, Beer-Sheva, Israel

A wind streak is a collective term for a variety of aeolian features that when viewed from above appears as distinctive albedo surface patterns aligned or marking the primary near surface wind direction. They are discernable as bright and dark patterns due to alterations in surface characteristics or to presence of bedforms deposition of erosion of particles on the surface and along the drift direction. Wind streaks, thus, indicate the prevailing wind direction at the time of their formation and have been used to map near-surface winds and to estimate atmospheric circulation patterns on Mars and Venus. However, because wind streaks were studied mostly on Mars and Venus, much of the knowledge regarding their formation mechanism and time-scales for their formation are barely known nor studied. The aim of this research is to study Earth wind streaks. Wind streak orientations from the new Earth wind streaks database, were statistically correlated to Resultant Drift Direction (RDD) values calculated from reanalysis and 621 ground stations wind data. Results show good agreement between the wind streak orientations and the reanalysis RDD-0.78. In contrast, a rather low correlation was found between the wind streaks and the ground stations - 0.47. Higher correlations in favor of the reanalysis were demonstrated when segmented by continent, ranging from 0.641 in North America to 0.922 in Antarctica. Further investigations are being conducted for sites where wind streak orientations did not correspond to the RDDs (difference >45). For most sites where an incompatibility was found, seasonal and diurnal variations in the wind flow are responsible for deviation from the global pattern. The rest may be explained by either the influence of local topography on the regional wind flow or that these wind streaks were not formed under the current wind regime. The results indicate that most Earth wind streaks were formed under the modern wind regime. They are indeed indicative of long-term prevailing wind direction on global and regional scales.