Coriolis effect recorded in Late Pleistocene Marine Isotope Stage 5e Bahamian aeolianites

Abstract

Abstract The windward islands of the Lucayan Archipelago (Bahamas) form an Atlantic Ocean–facing transect spanning >950 km in length and 6° of latitude. The islands' topography is largely constructed from carbonate wind-blown dunes (i.e., aeolianites) deposited during the interglacial phases of the Late Pleistocene and Holocene. New digital elevation data from satellite radar interferometry (TanDEM-X German Earth observation satellite) enables a step change in the ability to map and quantify Bahamian aeolian landforms across the archipelago. A semi-automated mapping approach that leverages object-based image analysis yields a total aeolianite area of ~1674 km2 across Great Abaco, Eleuthera, Cat, San Salvador, Long, Crooked, Acklins, and Mayaguana islands (Bahamas) and the Turks and Caicos Islands. Longitudinal axis measurements from 747 Pleistocene parabolic dunes record increasing consistency of east-west orientation with decreasing latitude. Three U.S. National Data Buoy Center data buoys provided modern wind direction and velocity measurements (n = 730,933 of each) along this transect. Analysis of wind vectors (>P90 [90th percentile], n = 70,095) demonstrates increasing organization of easterlies at southern latitudes and an offset in directionality compared to formational winds of Pleistocene Marine Isotope Stage (MIS) 5e deposits. Southward trends of increasing wind strength and consistency reflect geostrophic flow driven by atmospheric circulation within the Hadley cell and right-hand deflection of the Coriolis effect in the Northern Hemisphere. We propose that the offset in directionality between dune axes and modern wind vectors is related to changes in latitudinal width of the Hadley cell from the Late Pleistocene (MIS 5e) to today. This data set is robust enough to serve as a benchmark against which future atmospheric circulation models can be compared.