A software "tool kit" in C for the application of spherical geodesic gridsin paleoclimatology

A popular technique in paleoclimatology is the definition of occurrences of climate-sensitive lithofacies, such as evaporite deposits, using a global grid system. The simplest and most widely used grid systems in paleoclimato logy are orthogonal grids that use lines of latitude and longitude as grid- cell boundaries. Occurrences defined using orthogonal grids, however, can d iffer greatly in size and shape because lines of longitude converge at the poles, distorting the shape of the grid system. As a result of this distort ion, the latitude at which the occurrences were defined can affect the numb er and distribution of occurrences. As an alternative, spherical geodesic s ystems can be used. Spherical geode sic systems have near-equal area and ne ar-equal shape grid-cells for the entire sphere, which significantly reduce biases introduced by the grid system. Spherical geodesic systems can make paleoclimatic studies using occurrences of climate-sensitive lithofacies mo re reliable. To make spherical geodesic systems practical for paleoclimate applications, a "tool kit" of programs written in C has been assembled. Fou r programs are included in the tool kit: DESIGNER, which designs spherical geodesic grids, PLOTTER, which generates import files for Terra Mobilis(TM) and PGIS/Mac(TM) to display the grids, MAPPER, which defines occurrences u sing the grids, and ROTATOR, which rotates data about Euler poles. Middle D evonian evaporite data for North America were compiled to demonstrate each of the functions. (C) 1998 Elsevier Science Ltd. All rights reserved.