[Origine physique du contraste entre activité électrique au dessus des terres et des océans]
L'origine du contraste prononcé entre activité électrique au dessus des terres et des océans est explorée à l'aide de concepts classiques et de nouvelles méthodes d'analyse. Le comportement des ı̂les, considérées comme similaires à des continents miniatures, est en faveur d'un contrôle de l'activité électrique par un mécanisme thermodynamique plutôt que par la présence d'aérosols. L'activité électrique au-dessus des ı̂les, considérées comme similaires à des continents miniatures, est pilotée par un mécanisme thermodynamique plutôt que par la présence d'aérosols. Les mesures de réflectivité radar dans le cadre de la mission TRMM (Tropical Rainfall Measuring Mission) soulignent le contraste important entre l'intensité des ascendances mesurées au dessus des terres et des océans. Cependant, ce contraste en termes d'ascendance ne peut pas être attribué à une différence d'instabilité convective potentielle (CAPE) déterminée en référence à la flottabilité des masses d'air. Ce problème est résolu en dimensionnant celles-ci selon l'altitude de la base du nuage, comme cela avait été suggéré lors d'études précédentes. Une convection continentale associée à une forte activité électrique est donc favorisée par un rapport de Bowen surfacique plus important et par une plus grande instabilité convective en couche limite. Ceci conduit à une transformation plus efficace de l'instabilité convective potentielle en énergie cinétique des courants ascendants nuageux.
New tests and older ideas are explored to understand the origin of the pronounced contrast in lightning between land and sea. The behavior of islands as miniature continents with variable area supports the traditional thermal hypothesis over the aerosol hypothesis for lightning control. The substantial land–ocean contrast in updraft strength is supported globally by TRMM (Tropical Rainfall Measuring Mission) radar comparisons of mixed phase radar reflectivity. The land–ocean updraft contrast is grossly inconsistent with the land–ocean contrast in CAPE (Convective Available Potential Energy), from the standpoint of parcel theory. This inconsistency is resolved by the scaling of buoyant parcel size with cloud base height, as suggested by earlier investigators. Strongly electrified continental convection is then favored by a larger surface Bowen ratio, and by larger, more strongly buoyant boundary layer parcels which more efficiently transform CAPE to kinetic energy of the updraft in the moist stage of conditional instability.
Mot clés : aérosols, convection, foudre, thermique, orages, ascendances
Earle Williams 1 ; Sharon Stanfill 2
@article{CRPHYS_2002__3_10_1277_0, author = {Earle Williams and Sharon Stanfill}, title = {The physical origin of the land{\textendash}ocean contrast in lightning activity}, journal = {Comptes Rendus. Physique}, pages = {1277--1292}, publisher = {Elsevier}, volume = {3}, number = {10}, year = {2002}, doi = {10.1016/S1631-0705(02)01407-X}, language = {en}, }
Earle Williams; Sharon Stanfill. The physical origin of the land–ocean contrast in lightning activity. Comptes Rendus. Physique, Volume 3 (2002) no. 10, pp. 1277-1292. doi : 10.1016/S1631-0705(02)01407-X. https://comptes-rendus.academie-sciences.fr/physique/articles/10.1016/S1631-0705(02)01407-X/
[1] The distribution of thunderstorms over the globe, Geophys. Mem. London, Volume 24 (1925), pp. 147-164
[2] On the association of the diurnal variation of electric potential gradient in fine weather with the distribution of thunderstorms over the globe, Quart. J. Roy. Met. Soc, Volume 55 (1929), pp. 1-17
[3] Some topics in atmospheric electricity (L.G. Smith, ed.), Recent Advances in Atmospheric Electricity, Pergamon Press, 1958, pp. 5-16
[4] The global distribution of midnight lightning: December 1977 to August 1978, Mon. Wea. Rev, Volume 114 (1986), pp. 2640-2653
[5] et al. The lightning imaging sensor, Proceedings 11th Int. Conf. on Atmospheric Electricity, Guntersville, AL, NASA/CP-1999-209261, 1999, pp. 746-749
[6] The local diurnal variation of cloud electrification and the global diurnal variation of negative charge on the earth, J. Geophys. Res, Volume 98 (1993), pp. 5221-5234
[7] An analysis of the conditional instability of the tropical atmosphere, 121 (1993), pp. 21-36
[8] The Schumann resonance: a global tropical thermometer, Science, Volume 256 (1992), pp. 1184-1187
[9] Global circuit response to seasonal variations in global surface air temperature, Mon. Wea. Rev, Volume 122 (1994), pp. 1917-1929
[10] Global circuit response to temperature on distinct time scales: A status report (M. Hayakawa, ed.), Atmospheric and Ionospheric Phenomena Associated with Earthquakes, Terra Scientific, Tokyo, 1999
[11] Global surface temperatures and the atmospheric electric circuit, Geophys. Res. Lett, Volume 20 (1993), p. 1363
[12] Global lightning and climate variability inferred from ELF field variations, Geophys. Res. Lett, Volume 24 (1998), pp. 2411-2414
[13] Lightning activity as an indicator of climate change, Quart. J. Roy. Met. Soc, Volume 125 (1999), pp. 893-903
[14] Ionospheric potential as a proxy index for global temperature, Atmos. Res, Volume 51 (1999), pp. 309-314
[15] A. Gettelman, D.J. Seidel, M.C. Wheeler, R.J. Ross, Multi-decadal trends in tropical convective available potential energy, J. Geophys. Res., 2002, in press
[16] Reply to Michaud, L.M., Comment on “Convective available potential energy in the environment of oceanic and continental clouds”, J. Atmos. Sci, Volume 53 (1996), pp. 1212-1214
[17] Environmental characteristics of convective systems during TRMM-LBA, Mon. Wea. Rev, Volume 130 (2002), pp. 1493-1509
[18] Aerosol effect on cloud droplet size monitored by satellite, Science, Volume 295 (2002), pp. 834-838
[19] E.R. Williams, et al., Contrasting convective regimes over the Amazon: Implications for cloud electrification, J. Geophys. Res., 2002, in press
[20] Enhancement of cloud-to-ground lightning over Houston, Texas, Geophys. Res. Lett, Volume 28 (2001), pp. 2597-2600
[21] Clouds and Storms: The Behavior and Effect of Water in the Atmosphere, Pennsylvania State University Press, 1980
[22] Storm and Cloud Dynamics, Academic Press, 1989
[23] H.R. Byers, R.R. Braham, The thunderstorm project, U.S. Weather Bureau, U.S. Dept. of Commerce, Washington, DC, 1949
[24] Cumulonimbus vertical velocity events in GATE. Part I: Diameter, intensity and mass flux, J. Atmos. Sci, Volume 37 (1980), pp. 2444-2457
[25] WMO, World distribution of thunderstorm days, WMO/OMM, No. 21.TP. 21, Parts I and II, 1956
[26] The electrification of severe storms (C.A. Doswell, ed.), Severe Convective Storms, American Meteorological Society, 2001, pp. 527-561
[27] A radar and electrical study of tropical ‘hot towers’, J. Atmos. Sci, Volume 49 (1992), pp. 1386-1395
[28] A computational study of the relationships linking lightning frequency and other thundercloud parameters, Quart. J. Roy. Met. Soc, Volume 121 (1995), pp. 1525-1548
[29] Relationships between lightning activity and various thundercloud parameters: Satellite and modeling studies, Atmos. Res, Volume 51 (1999), pp. 221-236
[30] Meteorological variation of maritime aerosols (A.F. Roddy; P.C. O'Connor, eds.), Atmospheric Aerosols and Nuclei, Galway University Press, Galway, Ireland, 1977, pp. 503-507
[31] Vertical velocity characteristics of oceanic convection, J. Atmos. Sci, Volume 46 (1989), pp. 621-640
[32] Vertical velocity in oceanic convection off tropical Australia, J. Atmos. Sci, Volume 51 (1994), pp. 3183-3193
[33] Severe local storms in the tropics (C.A. Doswell, ed.), Severe Convective Storms, Meteorological Monographs, American Meteorological Society, 2001, pp. 359-432
[34] E.J. Zipser, Some views on ‘hot towers’ after 50 years of tropical field programs and two years of TRMM data, in: Meteorological Monographs, American Meteorological Society, 2002, in press
[35] Cumulus cloud properties derived using Landsat satellite data, J. Clim. Appl. Met, Volume 25 (1986), pp. 261-276
[36] The Down Under Doppler and Electricity Experiment (DUNDEE): Overview and preliminary results, Bull. Am. Met. Soc, Volume 73 (1992), pp. 3-16
[37] Soaring over the open sea, Scientific Monthly, Volume 55 (1942), pp. 1-7
[38] Global Ocean Surface Temperature Atlas, UK Met. Office and Massachusetts Institute of Technology, 1990
[39] The parameterization of deep convection (R.K. Smith, ed.), The Physics and Parameterization of Moist Atmospheric Convection, NATO ASI Series C, 505, Kluwer Academic, Dordrecht, 1997, pp. 255-279
[40] Turbulent gravitational convection for maintained and instantaneous sources, Proc. Roy. Soc. London A, Volume 234 (1956), pp. 1-23
[41] The composite shape and structure of coherent eddies in the convective boundary layer, Boundary-Layer Meteor, Volume 61 (1992), pp. 213-245
[42] Mixing in thermals with and without buoyancy reversal, J. Atmos. Sci, Volume 49 (1992), pp. 1412-1426
[43] Fitting measurements of thunderstorm updraft profiles to model profiles, Mon. Wea. Rev, Volume 104 (1976), pp. 611-617
[44] Severe Convective Storms, Meteorological Monographs, 28, American Meteorological Society, November 2001
[45] On the heat balance in the equatorial trough zone, Geophysica, Volume 6 (1958), pp. 503-538
[46] Atlas of the Surface Heat Balance of the Continents, Gebrider Bortraeger, Berlin, 1989
[47] The Evolution of the Biosphere, Reidel, 1986
[48] The impact of simulated storm structure and intensity on variations in the mixed layer and moist layer depths, Mon. Wea. Rev, Volume 130 (2002), pp. 1722-1748
[49] Radar, passive microwave and lightning characteristics of precipitating systems in the tropics, Mon. Wea. Rev, Volume 130 (2002), pp. 802-824
[50] Conditional instability and lightning activity in Gabarone, Botswana, Meteorol. Atmos. Phys, Volume 62 (1993), pp. 169-175
[51] Global lightning variations caused by changes in thunderstorm flash rate and by changes in the number of thunderstorms, J. Appl. Met, Volume 39 (2000), pp. 2223-2230
[52] Structure and characteristics of precipitation systems observed by TRMM, Preprints, 11th Conf. On Satellite Meteorology and Oceanography, 15–18 October, Madison, WI, American Meteorological Society, Boston (2001), pp. 464-467
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