COLLABORATIVE RESEARCH: Complexity and Paleodynamics of Natural Sand Dune Fields

自然沙丘场的复杂性和古动力学沙丘场呈现出一些在地球和其他行星（如火星）上看到的最有趣的模式。沙丘是由风吹来的沙粒形成的，它们堆积成小土丘，最终演变成装饰日历和邮票的优雅形状。风的特征，如风向和沙的供应，以这样一种方式烙印在沙丘的模式上，因此，只要仔细研究沙丘的模式，就有可能说明导致其形成的气候条件。随着时间的推移，风和沙的供应发生了变化，沙丘的模式也在以一种尚未完全描述的方式缓慢变化。储存在非洲、中东、亚洲、澳大利亚和北美的大沙丘地区的过去数千年至数万年的气候信息，可能为预测区域气候和景观对人类引起的全球气候变化的反应提供关键的理解。PIs的目标是发展一种从沙丘模式推断过去气候的方法，并将其应用于三个天然沙丘场。为了实现这一目标，他们开发了跨越沙丘和沙丘场对气候变化作出反应的时间段的数值模型：(1)沙丘场的总体特征模型，包括沙丘之间的间距及其方向（数千年）；(2)沙丘顶线（数百年）的运动轨迹模型；(3)沙丘形态变化模型（几十年）。这些模型将用于研究加利福尼亚东南部的阿尔戈多内斯沙丘场、纳米比亚西部纳米比亚沙漠的沙丘和毛里塔尼亚西部沙漠的沙丘的发展。pi对过去气候的解释将通过在充满沙子的风洞中利用它们的气候推断来尝试重建这三个沙丘场的模式来进行测试。

BSTRACTCOMPLEXITY AND PALEODYNAMICS OF NATURAL SAND DUNE FIELDSGary KocurekEAR-0106603Fields of sand dunes present some of the most intriguing patterns seen on Earth and other planets, such as Mars. The dunes form when wind transports sand grains, causing them to pile up into small mounds that eventually evolve into the graceful shapes that adorn calendars and postage stamps. The characteristics of the wind, such as its direction and the supply of sand, are imprinted on the pattern of dunes in such a way that it is possible, just by carefully examining the dune pattern, to say something about the climatic conditions that lead to its creation. As winds and sand supply change through time, the pattern of dunes slowly changes as well in ways that are not yet fully delineated. The information about climate over the past thousands to tens of thousands of years stored in the great sand dune fields of Africa, the Middle East, Asia, Australia and North America might provide critical understanding in predicting the reaction of regional climates and landscapes to human-induced global climate change. PIs aim is to develop a methodology for inferring past climate from dune patterns and to apply it to three natural dune fields. To achieve this goal, they have developed numerical models that span the range of time periods over which dunes and dune fields can react to changes in climate: (1) a model for the overall characteristics of dune fields, including spacing between dunes and their orientation (thousands of years); (2) a model for the motion of the trace of the tops of dunes, their crestlines (hundreds of years); and (3) a model for the changes in shapes of dunes (tens of years). These models will be used to investigate the development of the Algodones dune field in southeastern California, the dunes of the Namibian desert in western Namibia, and the dunes of the deserts of western Mauritania. The interpretations PIs derive regarding past climate will be tested by attempting to recreate the patterns of these three dune fields using their climatic inferences in a wind tunnel filled with sand.