Variation in Dune Lee-Side Airflow and Its Significance

Expand
  • 1. Key Laboratory of Environmental Change and Natural Disaster, the Ministry of Education of China, Institute of Resources Science, Beijing Normal University, Beijing 100875;
    2. Shapotou Experimental Station of Desert Research, CAS Lanzhou, Gansu 730000

Received date: 2000-04-20

  Revised date: 2000-10-25

  Online published: 2000-11-20

Abstract

Data from different types of dunes suggest that the near surface air-flow over dune lee side varied with dune morphology and primary wind direction relative to dune crest-line. It is found that three types of secondary air-flow exist according to their directions and magnitudes, they are: return flow, attached and not deflected flow, and attached and deflected flow. Return flow, characterized by lower velocity, occurred on stepper lee slops in transverse flow conditions; attached flow with higher wind velocity occurred on gentle lee slops. The attached flow could be deflected in the oblique primary wind environment but not deflected in transverse flow conditions, and its magnitude is the cosine function of primary wind direction relative to dunes . According to the nature of three types of secondary flow, the authors expound the corresponding sedimentary processes and possible stratification types, and also discuss the aeolian cross-strata as an indicator of paleowind environment.

Cite this article

HA Si, WANG Gui-yong . Variation in Dune Lee-Side Airflow and Its Significance[J]. SCIENTIA GEOGRAPHICA SINICA, 2000 , (6) : 573 -576 . DOI: 10.13249/j.cnki.sgs.2000.06.573

References

[1] Hunter R E. Basic types of stratification in small aeolian sand dunes[J]. Sedimentology, 1977 24: 361-388.
[2] Kocurek G, Dott Jr R H. Distinction and uses of stratification types in the interpretation of eolian sand[J]. J. Setiment. Petro
[3] Phy K, Tsoar H. Aeolian sand and Sand Dunes[M]. London: Unwin Hyman,1990. 392.
[4] Lancaster N. Geomorphology of Desert Dunes[M]. London: Routaledge, 1995.345.
[5] Hoyt J H. Air and sand movement in the lee of eolian sand dunes[J].Sedimentology 1966,7:137-144.
[6] Franck a, Kocurek G.Lee side airflow model of aeolian sand dunes[J]. Sedimentology 1996,451-458.
[7] Hunter R A. Kinematic model for the structure of lee-side deposition[J]. Sedimentarology,1985,32:409-422.
[8] Anderson R S. The pattern of grainfall deposition in the lee of eolian dunes[J]. Sedimentology, 1988, 35:175-185.
[9] McDonald R R, Anderson R S. Experimental verification of aeolian saltation and lee side deposition models[J]. Sedimentology, 1995, 42:39-56.
[10] Howard A D. Effect of slope on the threshold of motion and its application to orientation of wind ripples[J]. Geol. Soc. Am. Bull, 1977, 88:853-856.
[11] Havholm K, Kocurek G. A preliminary study of the dynamics of the modern draa, Algodonis, southeastern California,USA[J]. Sedimentology,1988, 35: 649-669.
[12] Lancaster N. The dynamics of star dunes: an example from the Gran Desieerto, Mexico[J]. Sedimentology, 1989,36:273-289.
[13] Jackson P S and Hunt J C R. Turbulent winds flow over a low hill[J].Q.J.R.Metro.Soc.1975, 101: 939-955.
[14] Tsoar H. Dynamic processes acting on a longitudinal (seif) dune[J]. Sedimentology,1983, 30: 567-578 .
[15] Sweet M L , Kocurek G. An empirical model of aeolian dune lee-face airflow[J]. Sedimentary Geology, 1990,37:1023-1038.
[16] Rubin D, Hunter R.Reconstractig bedforms from compound cross-bedding. In:Brookfield M E,Ahlbrandt T S. Eolian Sediment and Processes. Amsterdam: Elsever, 1983.407-427.
[17] Tsoer H,Yaalon D H. deflection of sand movement a long-itudinal (seif)dune:Use of fluorescent dye as a tracer [J]. Sedimentology, 1983,36:25-39.
[18] Handisty J, Whitehouse R J S. Evidence for a new sand tran-sport process from experiments on Saharan dunes[J]. Nature, 1988, 332:532-534 .
[19] Fryberger S G. Dune forms and wind regime. In: McKee E D. A Study of Global Sand Seas. Washington: Prof. Pap. US Geol. Surv. 1052,1979.137-169.
Outlines

/