The distribution of
mineral dust around topographical obstacles is examined, employing the
dimensionless Froude number that describes different flow regimes in a fluid.
Flow around a peak with a near-circular shape in a dusty environment like the
Sahara and the Sahel was examined in order to investigate the distribution of
the dust around the obstacle. The Total Ozone Mapping Spectrometer Aerosol
Index (TOMS-AI) daily Aerosol Index, the u and v wind components and the
temperature, were used for the period 1979-1992,i.e. 14 years. It is found by
the AI data that the shape of the dust distribution around the circular peak is
in good agreement with the shape of the peak itself. Additionally good
correlation exists between the vertical distribution of the dust above the peak
and the Froude Number in its vicinity. This method allows for the first time
the investigation of the flow above and around topographical obstacles in
different flow conditions in the open space employing dust as the flow tracer.
References
[1]
Chomaz, J.M., Bonneton, P., Butet, A. and Perrier, M. (1992) Froude Number Dependence of the Flow Separation Line on a Sphere Towed in a Stratified Fluid. Physics of Fluids A, 4, 254-258. http://dx.doi.org/10.1063/1.858353
[2]
Smolarkiewitz, P.K. and Rotunno, R. (1989) Low Froude Number Flow past Three Dimensional Obstacles Part I: Baroclinically Generated Lee Vortices. Journal of the Atmospheric Sciences, 46, 1154-1164.
http://dx.doi.org/10.1175/1520-0469(1989)046<1154:LFNFPT>2.0.CO;2
[3]
Smolarkiewitz, P.K. and Rotunno, R. (1990) Low Froude Number Flow past Three Dimensional Obstacles Part II: Flow Reversal Zone. Journal of the Atmospheric Sciences, 47, 1498-1511.
http://dx.doi.org/10.1175/1520-0469(1990)047<1498:LFNFPT>2.0.CO;2
[4]
Reisner, J.M. and Smolarkiewitz, P.K. (1994) Thermally Forced Low Froude Number Flow past Three Dimensional Obstacles. Journal of the Atmospheric Sciences, 51, 117-133.
[5]
Hughes, R.L. and Ofosu, K.N. (1987) Froude Number Effects on Flow over Topography. Geophysical & Astrophysical Fluid Dynamics, 38, 177-191. http://dx.doi.org/10.1080/03091928708219203
[6]
Dubovik, O., Lapyonok, T., Kaufman, Y.J., Chin, M., Ginoux, P., Kahn, R.A. and Sinyuk, A. (2008) Retrieving Global Aerosol Sources from Satellites Using Inverse Modeling. Atmospheric Chemistry and Physics, 8, 209-250.
http://dx.doi.org/10.5194/acp-8-209-2008
[7]
Chin, M., Chu, A., Levy, R., Remer, L., Kaufman, Y., Holben, B., Eck, T., Ginoux, P. and Gao, Q.X. (2004) Aerosol Distribution in the Northern Hemisphere during ACE-Asia: Results from Global Model, Satellite Observations, and Sun Photometer Measurements. Journal of Geophysical Research-Atmospheres, 109, D23S90.
http://dx.doi.org/10.1029/2004JD004829
[8]
Jaenicke, R. (1990) Problems of the Distribution of the Global Aerosol. Russian Chemical Reviews, 59, 959-972.
http://dx.doi.org/10.1070/RC1990v059n10ABEH003569
[9]
Stull, R. (1988) An Introduction to Boundary Layer Meteorology. Kluwer Academic Publication, 666 p.
http://dx.doi.org/10.1007/978-94-009-3027-8
[10]
Herman, J.R. and Celarier, E. (1997) Earth Surface Reflectivity Climatology at 340-380 nm from TOMS Data. Journal of Geophysical Research, 102, 28003-28011. http://dx.doi.org/10.1029/97JD02074
[11]
Alpert, P., Krichak, S.O., Tsidulko, M., Shapir, H. and Joseph, H. (2002) A Dust Prediction System with TOMS Initialization. Monthly Weather Review, 130, 2335-2345.
http://dx.doi.org/10.1175/1520-0493(2002)130<2335:ADPSWT>2.0.CO;2
[12]
Torres, O., Bhartia, P.K., Herman, J.R., Sinyuk, A., Ginoux, P. and Holben, B. (2002) A Long-Term Record of Aerosol Optical Depth from TOMS Observations and Comparison to Aeronet Measurements. Journal of the Atmospheric Sciences, 59, 398-413. http://dx.doi.org/10.1175/1520-0469(2002)059<0398:ALTROA>2.0.CO;2
[13]
Prospero, J.M., Ginoux, P.O., Torres, S., Nicholson, E. and Gill, T.E. (2002) Environmental Characterization of Global Sources of Atmospheric Soil Dust Identified with the NIMBUS 7 Total Ozone Mapping Spectrometer (TOMS) Absorbing Aerosol Product. Reviews of Geophysics, 40, 1002. http://dx.doi.org/10.1029/2000RG000095
[14]
Israelevitch, P.L., Levin, Z., Joseph, J.H. and Ganor, E. (2002) Desert Aerosol Transport in the Mediterranean Regionas Inferred from the TOMS Aerosol Index. Journal of Geophysical Research, 107, 4572.
http://dx.doi.org/10.1029/2001JD002011
