Publications
107 results found
Müller-Wodarg D, 2002, Johann Heinrich!von Thunen and Carl!Pogge, Conference on Thuenen Ideas in Theory and Practice, Publisher: LANDWIRTSCHAFTSVERLAG GMBH, Pages: 152-156, ISSN: 0005-9080
Muller-Wodarg ICF, 2002, The application of general circulation models to the atmospheres of terrestrial-type moons of the giant planets, Atmospheres in the solar system: comparative aeronomy, Editors: Mendillo, Nagy, Waite, Washington D.C., Publisher: American Geophysical Union, Pages: 307-318, ISBN: 9780875909899
Müller-Wodarg ICF, 2002, The application of general circulation models to the atmospheres of terrestrial-type moons of the giant planets, Yosemite Conference on Comparative Aeronomy in the Solar System, Publisher: AMER GEOPHYSICAL UNION, Pages: 307-318, ISSN: 0065-8448
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- Citations: 2
Millward GH, Muller-Wodarg ICF, Aylward AD, et al., 2001, An investigation into the influence of tidal forcing on F region equatorial vertical ion drift using a global ionosphere-thermosphere model with coupled electrodynamics (Article no. 2000JA000342), Journal of Geophysical Research, Vol: 106, Pages: 24733-24744, ISSN: 0148-0227
Muller-Wodarg IC, Aylward AD, Fuller-Rowell TJ, 2001, Tidal oscillations in the thermosphere: a theoretical investigation of their sources, Journal of Atmospheric and Solar Terrestrial Physics, Vol: 63, Pages: 899-914, ISSN: 1364-6826
Müller-Wodarg ICF, Yelle RV, Mendillo M, et al., 2000, The thermosphere of Titan simulated by a global three-dimensional time-dependent model, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 105, Pages: 20833-20856, ISSN: 2169-9380
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- Citations: 58
Rishbeth H, Müller-Wodarg ICF, Zou L, et al., 2000, Annual and semiannual variations in the ionospheric F2-layer: II. Physical discussion, Annales Geophysicae, Vol: 18, Pages: 945-956
<jats:p>Abstract. The companion paper by Zou et al. shows that the annual and semiannual variations in the peak F2-layer electron density (NmF2) at midlatitudes can be reproduced by a coupled thermosphere-ionosphere computational model (CTIP), without recourse to external influences such as the solar wind, or waves and tides originating in the lower atmosphere. The present work discusses the physics in greater detail. It shows that noon NmF2 is closely related to the ambient atomic/molecular concentration ratio, and suggests that the variations of NmF2 with geographic and magnetic longitude are largely due to the geometry of the auroral ovals. It also concludes that electric fields play no important part in the dynamics of the midlatitude thermosphere. Our modelling leads to the following picture of the global three-dimensional thermospheric circulation which, as envisaged by Duncan, is the key to explaining the F2-layer variations. At solstice, the almost continuous solar input at high summer latitudes drives a prevailing summer-to-winter wind, with upwelling at low latitudes and throughout most of the summer hemisphere, and a zone of downwelling in the winter hemisphere, just equatorward of the auroral oval. These motions affect thermospheric composition more than do the alternating day/night (up-and-down) motions at equinox. As a result, the thermosphere as a whole is more molecular at solstice than at equinox. Taken in conjunction with the well-known relation of F2-layer electron density to the atomic/molecular ratio in the neutral air, this explains the F2-layer semiannual effect in NmF2 that prevails at low and middle latitudes. At higher midlatitudes, the seasonal behaviour depends on the geographic latitude of the winter downwelling zone, though the effect of the composition changes is modified by the large solar zenith angle at midwinter. The zenith angle effect is especially important in longitudes far from the magnetic poles. Here, the downwelling o
Zou L, Rishbeth H, Müller-Wodarg ICF, et al., 2000, Annual and semiannual variations in the ionospheric F2-layer. I. Modelling, Annales Geophysicae, Vol: 18, Pages: 927-944
<jats:p>Abstract. Annual, seasonal and semiannual variations of F2-layer electron density (NmF2) and height (hmF2) have been compared with the coupled thermosphere-ionosphere-plasmasphere computational model (CTIP), for geomagnetically quiet conditions. Compared with results from ionosonde data from midlatitudes, CTIP reproduces quite well many observed features of NmF2, such as the dominant winter maxima at high midlatitudes in longitude sectors near the magnetic poles, the equinox maxima in sectors remote from the magnetic poles and at lower latitudes generally, and the form of the month-to-month variations at latitudes between about 60°N and 50°S. CTIP also reproduces the seasonal behaviour of NmF2 at midnight and the summer-winter changes of hmF2. Some features of the F2-layer, not reproduced by the present version of CTIP, are attributed to processes not included in the modelling. Examples are the increased prevalence of the winter maxima of noon NmF2 at higher solar activity, which may be a consequence of the increase of F2-layer loss rate in summer by vibrationally excited molecular nitrogen, and the semiannual variation in hmF2, which may be due to tidal effects. An unexpected feature of the computed distributions of NmF2 is an east-west hemisphere difference, which seems to be linked to the geomagnetic field configuration. Physical discussion is reserved to the companion paper by Rishbeth et al.Key words: Atmospheric composition and structure (thermosphere-composition and chemistry) - Ionosphere (mid-latitude ionosphere; modelling and forecasting) </jats:p>
Rishbeth H, Müller-Wodarg ICF, Zou L, et al., 2000, Annual and semiannual variations in the ionospheric F2-layer:: II.: Physical discussion, ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, Vol: 18, Pages: 945-956, ISSN: 0992-7689
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- Citations: 218
Zou L, Rishbeth H, Müller-Wodarg ICF, et al., 2000, Annual and semiannual variations in the ionospheric F2-layer.: I.: Modelling, ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, Vol: 18, Pages: 927-944, ISSN: 0992-7689
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- Citations: 125
Aruliah AL, Müller-Wodarg ICF, Schoendorf J, 1999, Consequences of geomagnetic history on the high-latitude thermosphere and ionosphere:: Averages, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 104, Pages: 28073-28088, ISSN: 2169-9380
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- Citations: 15
Rishbeth H, Müller-Wodarg ICF, 1999, Vertical circulation and thermospheric composition: a modelling study, Annales Geophysicae, Vol: 17, Pages: 794-805
<jats:p>Abstract. The coupled thermosphere-ionosphere-plasmasphere model CTIP is used to study the global three-dimensional circulation and its effect on neutral composition in the midlatitude F-layer. At equinox, the vertical air motion is basically up by day, down by night, and the atomic oxygen/molecular nitrogen [O/N2] concentration ratio is symmetrical about the equator. At solstice there is a summer-to-winter flow of air, with downwelling at subauroral latitudes in winter that produces regions of large [O/N2] ratio. Because the thermospheric circulation is influenced by the high-latitude energy inputs, which are related to the geometry of the Earth's magnetic field, the latitude of the downwelling regions varies with longitude. The downwelling regions give rise to large F2-layer electron densities when they are sunlit, but not when they are in darkness, with implications for the distribution of seasonal and semiannual variations of the F2-layer. It is also found that the vertical distributions of O and N2 may depart appreciably from diffusive equilibrium at heights up to about 160 km, especially in the summer hemisphere where there is strong upwelling. Atmospheric composition and structure (thermosphere · composition and chemistry) · Ionosphere (ionosphere · atmosphere interactions) </jats:p>
Rishbeth H, Müller-Wodarg ICF, 1999, Vertical circulation and thermospheric composition:: a modelling study, ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES, Vol: 17, Pages: 794-805, ISSN: 0992-7689
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- Citations: 83
Muller-Wodarg ICF, Aylward AD, Lockwood M, 1998, Effects of a mid-latitude solar eclipse on the thermosphere and ionosphere - A modelling study, GEOPHYSICAL RESEARCH LETTERS, Vol: 25, Pages: 3787-3790, ISSN: 0094-8276
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- Citations: 88
Achilleos N, Miller S, Tennyson J, et al., 1998, JIM: A time-dependent, three-dimensional model of Jupiter's thermosphere and ionosphere, Conference on Magnetospheres of the Outer Planets, Publisher: AMER GEOPHYSICAL UNION, Pages: 20089-20112, ISSN: 2169-9097
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- Citations: 109
Muller-Wodarg I, Aylward AD, 1998, The influence of tides on composition of the thermosphere, CO 1 and C4 1 Symposia of COSPAR Scientific Commission C - Atmospheric Tidal Dynamics and E-Region and D-Region Physics, at the 31st COSPAR Scientific Assembly, Publisher: PERGAMON PRESS LTD, Pages: 807-810, ISSN: 0273-1177
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- Citations: 11
Muller-Wodarg ICF, 1997, Modelling perturbations propagating through the mesopause into the earth's upper atmosphere, OBSERVATORY, Vol: 117, Pages: 388-388, ISSN: 0029-7704
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