When geology and climate collide: evolving landscapes and the wind-albedo wind feedback
Abstract
Low-level air movement across arid regions sends dust into the atmosphere and has the potential to modify surface and atmospheric conditions, and ocean chemistry. As such, it is necessary to accurately model these winds on various timescales and spatial resolutions. Modern stony deserts constitute a sizeable fraction of the Asian continental interior, and are currently low dust-emitting surfaces. If these areas were once covered by mud, silt, or sand dominated strata, they may have acted as major dust source regions in the past. Modeling winds in these areas with high fidelity, while taking into account changing landscapes and surface conditions, is important to understanding past and future climate systems. Here we use the Weather Research and Forecasting (WRF) model over part of the western Gobi Desert in China to show for the first time a previously undocumented paradox between landscape evolution and wind speeds. Near-surface winds have modified the radiative properties of the surface via winnowing of finer-grained particles, producing low albedo gravel mantled surfaces on 104-106-year timescales. The results show that the development of these low albedo surfaces results in higher sensible heating, and in turn increased horizontal and vertical wind speeds and turbulent kinetic energy (TKE). We found that a surface albedo reflecting initial conditions during aridification produces mean surface wind velocities and TKE that are up to 25% lower than what are observed today, while the basin-wide monthly average wind speeds fall by 8-10%. In addition, winds exiting the Hami Basin that move toward the Taklimakan Desert increase by up to 15%. Since these stony deserts are found globally, the climatically driven wind-albedo process we document in Asia has considerable implications for accurately simulating past and future climates beyond a regional scale.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP23B..05A
- Keywords:
-
- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 1625 Geomorphology and weathering;
- GLOBAL CHANGE;
- 5210 Planetary atmospheres;
- clouds;
- and hazes;
- PLANETARY SCIENCES: ASTROBIOLOGY;
- 5415 Erosion and weathering;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS