Short-period planetary waves in the Antarctic middle atmosphere |
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| Institution: | 1. Department of Physics and Astronomy, University of Canterbury, Christchurch 8020, New Zealand;2. Physical Sciences Division, British Antarctic Survey, Cambridge CB3 0ET, UK;3. NorthWest Research Associates/Colorado Research Associates Division, CO, USA;4. Australian Antarctic Division, 203 Channel Highway, Kingston, Tasmania 7050, Australia;5. The University of Adelaide, Adelaide, SA 5005, Australia;1. Department Física, PPGCTA, Universidade Estadual da Paraíba, UEPB, 58.109-790, Campina Grande-PB, Brazil;2. Institute for Meteorology, Leipzig University, Germany;3. Instituto Nacional de Pesquisas Espaciais, INPE, Brazil;1. Faculty of Education, Mus Alparslan University, 49250 Mus, Turkey;2. Technical Science Vocational School, Mus Alparslan University, 49100 Mus, Turkey;1. Department of Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL 61801, USA;2. Department of Engineering Physics, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA;1. National Atmospheric Research Laboratory (NARL), Gadanki, India;2. Department of Physics, Sri Venkateswara University, Tirupati, India;3. B1, CEEBROS, 47/20, IIIrd Main Road, Chennai, India;1. Department of Astronomy and Space Science, Chungnam National University, Daejeon 305-764, South Korea;2. Department of Physics, Govt. Degree College, Anantapur 515001, India;3. Atmosphere and Ocean Research Institute (AORI), The University of Tokyo, Chiba 277-8568, Japan;4. National Atmospheric Research Laboratory (NARL), Gadanki, Tirupati 517501, India;5. Department of Physics, Sree Vidyanikethan Engineering College, Tirupati 517102, India;6. Department of Physics, Sri Venkateswara University, Tirupati 517501, India |
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| Abstract: | Planetary waves with periods between two and four days in the middle atmosphere over Antarctica are characterized using one year of data from the medium-frequency spaced antenna (MFSA) radars at Scott Base, Rothera, and Davis. In order to investigate the origin of the observed waves, the ground-based data are complemented by temperature measurements from the Earth Observing System Microwave Limb Sounder (EOS MLS) instrument on the Aura satellite as well as wind velocity data from the United Kingdom Met. Office (UKMO) stratospheric assimilation. Observed characteristics of waves with a period of approximately two days in summer are consistent with the quasi-two-day wave (QTDW) generally found after the summer solstice at low- and mid-latitudes. The Scott Base observations of the QTDW presented here are the highest-latitude ground-based observations of this wave to date. Waves with preferred periods of two and four days occur in bursts throughout the winter with maximum activity in June, July, and August. The mean of the two- and four-day wave amplitudes is relatively constant, suggesting constant wave forcing. When several waves with different periods occur at the same time, they often have similar phase velocities, supporting suggestions that they are quasi-non-dispersive. In 2005, a “warmpool” lasts from late July to late August. An alternative interpretation of this phenomenon is the presence of a structure propagating with the background wind. Consideration of the role of vertical shear (baroclinic instabilities) and horizontal shear (barotropic instabilities) of the zonal wind suggests that instabilities are likely to play a role in the forcing of the two- and four-day waves, which are near-resonant modes and thus supported by the atmosphere. |
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