The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices We also discuss the physics of wind-blown sand and dune formation on Venus and Titan

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The physics of wind-blown sand and dust

The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.

/pdf/the-physics-of-wind-blown-sand-and-dust-4ggy9vm6xy.pdf

TERRESTRIAL ecosystems are thought to play an important role in determining regional and global climate1–6; one example of this is in Amazonia, where destruction of the tropical rainforest leads to warmer and drier conditions4–6. Boreal forest ecosystems may also affect climate. As temperatures rise, the amount of continental and oceanic snow and ice is reduced, so the land and ocean surfaces absorb greater amounts of solar radiation, reinforcing the warming in a 'snow/ice/albedo' feedback which results in large climate sensitivity to radiative forcings7–9. This sensitivity is moderated, however, by the presence of trees in northern latitudes, which mask the high reflectance of snow10,11, leading to warmer winter temperatures than if trees were not present12–14. Here we present results from a global climate model which show that the boreal forest warms both winter and summer air temperatures, relative to simulations in which the forest is replaced with bare ground or tundra vegetation. Our results suggest that future redistributions of boreal forest and tundra vegetation (due, for example, to extensive logging, or the influence of global warming) could initiate important climate feedbacks, which could also extend to lower latitudes.

Effects of boreal forest vegetation on global climate

All year long, massive airborne plumes of desert dust from the Sahara and surrounding regions are exported to the North Atlantic Ocean1 and the Mediterranean Sea2. The mass of African dust transported in the atmosphere is large—about one billion tonnes per year (ref. 3)—and it has been suggested that the wind-blown dusts have a substantial influence on the regional radiative budget4,5,6. Here we use daily satellite observations of airborne dusts7 to obtain an 11-year regional-scale analysis of dust transport out of Africa. The substantial seasonal variability over the Atlantic Ocean and Mediterranean Sea can be explained by the synoptic meteorology. Interannual variations in dust transport are similar over both regions, and are well correlated with the climatic variability defined by the North Atlantic Oscillation8. This large-scale climatic control on the dust export is effected through changes in precipitation and atmospheric circulation over the regions of dust mobilization and transport. Such natural variability is so large that it is difficult to resolve any anthropogenic influences on atmospheric dust loads, such as those due to desertification or land-use changes. It seems likely that the North Atlantic Oscillation will also affect the distribution—and radiative influence—of other aerosols.

Control of atmospheric export of dust from North Africa by the North Atlantic Oscillation

North African dust emissions and transport

A thoroughly objective method for the definition, selection and tracing of Mediterranean region cyclones is presented. The method is applied to the ECMWF 1982-1987 analyzed datasets to show monthly cyclone frequencies, cyclonic tracks and vertical variation of average relative vorticity. Day-to-night changes and vertical variation of cyclonic frequencies/vorticities indicate the importance of the sea thermal effect in the eastern Mediterranean. In the western Mediterranean and to a lesser extent in the Cyprus region, the lee cyclogenetic effect is very pronounced. Monthly cyclone tracks are presented and they clearly indicate the preferred routes of cyclonic movements. DOI: 10.1034/j.1600-0870.1990.00007.x

https://onlinelibrary.wiley.com/doi/pdf/10.1034/j.1600-0870.1990.00007.x

Climatological analysis of Mediterranean cyclones using ECMWF data

Objective calculated monthly cyclonic tracks in the Mediterranean are presented. The intermonthly variations within each season are shown to be quite significant and an particularly notable for December-January, April-May and June-July. We suggest that composite seasonal pictures are not faithful representations of the cyclonic routes over a complex terrain region like the Mediterranean.

Intermonthly Variability of Cyclone Tracks in the Mediterranean

The prevailing summer synoptic system in Israel―Subtropical high, not Persian Trough

The lows in the eastern Mediterranean (EM) based on the 1982–86 ECMWF data were classified according to some indicative variables of the low center's surroundings including horizontal scale, temperature, static instability, humidity, surface latent heat flux, baroclinicity and the jetstream location. A quite distinct group of cold meso-α scale (1300 km) cyclones was identified and named the CS (cold small-scale) cyclones. These Mediterranean CS cyclones were found to be characterized by higher-than-average vorticity for cyclones with a similar scale, stronger sea latent heat fluxes but also slightly enhanced baroclinicity and near average low-tropospheric static instability. DOI: 10.1034/j.1600-0870.1992.t01-1-00006.x

B. U. Neeman

Papers

Climatological analysis of Mediterranean cyclones using ECMWF data

Intermonthly Variability of Cyclone Tracks in the Mediterranean

The prevailing summer synoptic system in Israel―Subtropical high, not Persian Trough

Cold small-scale cyclones over the eastern Mediterranean