المؤلفون: Freitas, S. R., Longo, K. M., Chatfield, R., Dias, M. A. F. Silva, Andreae, M. O., Prins, E., Santos, J. C., Gielow, R., Carvalho Jr., J. A., Latham, D.

المصدر: Atmospheric Chemistry & Physics; 2007, Vol. 7 Issue 13, p3385-3398, 14p, 1 Chart, 13 Graphs

مصطلحات موضوعية: TRANSPORT theory, ATMOSPHERIC models, BIOMASS gasification, ATMOSPHERIC chemistry, SMOKE plumes, FIRES, CARBON dioxide, TROPOSPHERE

مستخلص: We describe and begin to evaluate a parameterization to include the vertical transport of hot gases and particles emitted from biomass burning in low resolution atmospheric-chemistry transport models. This sub-grid transport mechanism is simulated by embedding a 1-D cloud-resolving model with appropriate lower boundary conditions in each column of the 3-D host model. Through assimilation of remote sensing fire products, we recognize which columns have fires. Using a land use dataset appropriate fire properties are selected. The host model provides the environmental conditions, allowing the plume rise to be simulated explicitly. The derived height of the plume is then used in the source emission field of the host model to determine the effective injection height, releasing the material emitted during the flaming phase at this height. Model results are compared with CO aircraft profiles from an Amazon basin field campaign and with satellite data, showing the huge impact that this mechanism has on model performance. We also show the relative role of each main vertical transport mechanisms, shallow and deep moist convection and the pyro-convection (dry or moist) induced by vegetation fires, on the distribution of biomass burning CO emissions in the troposphere. [ABSTRACT FROM AUTHOR]

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المؤلفون: Santos, J. C.¹ santos@mps.mpg.de, Büchner, J.¹

المصدر: Astrophysics & Space Sciences Transactions (ASTRA). May2007, Vol. 3 Issue 1, p29-33. 5p.

مصطلحات موضوعية: *ELECTRIC currents, *PLASMA gases, *SOLAR atmosphere, *MAGNETOHYDRODYNAMICS, *ULTRAVIOLET radiation, *MAGNETIC fields

مستخلص: Photospheric plasma motion may cause the buildup of electric currents in the solar atmosphere. These electric currents may then dissipate and heat the corona, cause EUV and X-ray Bright Points (BPs) and trigger flares. In this work we use a 'data driven' 3D MHD model to study the generation of electric currents in the solar atmosphere by photospheric plasma motion. The model was applied to photospheric measurements below an observed EUV-BP. The observed photospheric magnetic field and the derived horizontal plasma motion were used as initial and boundary conditions of a simulation. The horizontal motion gave rise to electric currents in the chromosphere, transition region and lower corona. The currents formed in the area where the motion was applied and above the main concentrations of the photospheric magnetic field. [ABSTRACT FROM AUTHOR]