Evidence of internal gravity waves in the lower thermosphere at midlatitudes
Tóm tắt
Wind measurements were made by the CNR Meteor Radar Station at Budrio (45°N, 12°E) in the April–September 1978 period in order to emphasize the role of internal gravity (IG) waves in the lower thermosphere ((80÷110) km). After briefly describing the basic properties of these waves, we determine some of their characteristics using both the conventional spectral-analysis methods and alternatively, for short-time data series, the maximum-entropy method (MEM). The Fourier analysis of these data indicates that the gravity waves with periods of 2<8 h have amplitudes increasing with height (up to (30÷40) ms−1 at 100 km, in June), vertical wave-lengths of (8÷40) km and horizontal wave-lengths exceeding the corresponding ones by a factor of 50 or more. In May and September, by using the MEM method with a sampling of (10°20) min, gravity waves with periods of about 100 min and 2 h, respectively, have been tentatively identified. In August, the rates of energy loss per unit mass for internal gravity waves range from 0.015 to 0.045 W kg−1 in the (80°100) km region and the momentum deposition by these waves is 2.4 m s−1 h−1 at 90 km. Under some specific conditions, the observed accelerations of the prevailing wind ((3÷4) m s−1 d−1) due to momentum deposition over a period of 4 consecutive days (24–27 August) may approach the above-calculated maximum value.
Tài liệu tham khảo
citation_journal_title=Riv. Ital. Geofis.; citation_author=G. Cevolani; citation_volume=3; citation_publication_date=1976; citation_pages=8-8; citation_id=CR1
citation_journal_title=Riv. Meteorol. Aeronaut.; citation_author=G. Bortolotti, G. Cevolani, S. Gottardi, G. Grassi, F. Pedrini, P. Vangelista, F. Verniani; citation_volume=38; citation_publication_date=1978; citation_pages=1-1; citation_id=CR2
citation_journal_title=Bull. Astron. Inst. Czech.; citation_author=G. Cevolani, A. Hajduk; citation_volume=30; citation_publication_date=1979; citation_pages=297-297; citation_id=CR3
citation_journal_title=J. Atmos. Terr. Phys.; citation_author=F. Verniani, G. Cevolani, G. Grassi, F. Pedrini; citation_volume=42; citation_publication_date=1980; citation_pages=83-83; citation_doi=10.1016/0021-9169(80)90128-2; citation_id=CR4
G. Cevolani andA. Dardi:Atti Convegno AGI, Dicembre 6–7, 1979 (Roma, 1980), p. 230.
citation_journal_title=G. Fis.; citation_author=G. Cevolani, F. Pedrini; citation_volume=11; citation_publication_date=1980; citation_pages=83-83; citation_id=CR6
citation_journal_title=Can. J. Phys.; citation_author=C. O. Hines; citation_volume=38; citation_publication_date=1960; citation_pages=1441-1441; citation_id=CR7
citation_journal_title=Q. J. R. Meterol. Soc.; citation_author=C. O. Hines; citation_volume=89; citation_publication_date=1963; citation_pages=1-1; citation_id=CR8
citation_journal_title=Riv. Ital. Geofis.; citation_author=F. Verniani, M. Schaffner, G. Sinigaglia, G. Bortolotti, A. Dardi, C. Formiggini, C. Franceschi, S. Gottardi, G. Trivellone; citation_volume=23; citation_publication_date=1974; citation_pages=243-243; citation_id=CR9
G. M. Jenkins andD. W. Watts:Spectral Analysis and Its Applications (San Francisco, Cal., 1968), p. 525.
citation_journal_title=Rev. Geophys. Space Phys.; citation_author=T. J. Ulrich, T. N. Bishop; citation_volume=13; citation_publication_date=1975; citation_pages=183-183; citation_id=CR11
citation_journal_title=IEEE Trans. Syst. Sci. Cybern.; citation_author=E. T. Jaynes; citation_volume=4; citation_publication_date=1968; citation_pages=227-227; citation_id=CR12
citation_journal_title=Methods Comput. Phys.; citation_author=D. E. Smylie, G. K. C. Klarke, T. J. Ulrich; citation_volume=13; citation_publication_date=1973; citation_pages=391-391; citation_id=CR13
citation_journal_title=Ann. Inst. Statis. Math.; citation_author=H. Akaike; citation_volume=23; citation_publication_date=1971; citation_pages=163-163; citation_doi=10.1007/BF02479221; citation_id=CR14
citation_journal_title=J. Atmos. Terr. Phys.; citation_author=A. H. Manson, C. E. Meek, R. J. Stening; citation_volume=41; citation_publication_date=1979; citation_pages=325-325; citation_doi=10.1016/0021-9169(79)90114-4; citation_id=CR15
citation_journal_title=J. Geophys. Res.; citation_author=J. Weinstock; citation_volume=81; citation_publication_date=1976; citation_pages=633-633; citation_doi=10.1029/JA081i004p00633; citation_id=CR16
citation_journal_title=J. Atmos. Sci.; citation_author=M. A. Geller, H. Tanaka, D. C. Fritz; citation_volume=32; citation_publication_date=1975; citation_pages=2125-2125; citation_doi=10.1175/1520-0469(1975)032<2125:POTITV>2.0.CO;2; citation_id=CR17
C. O. Hines:The Upper Atmosphere in Motion (Washington, D. C., 1974), p. 741.
A. Spizzichino:Meteor trail radar winds over Europe, inThermospherie Circulation (Cambridge, 1972), p. 174.
C. O. Hines:Momentum deposition by atmospheric waves, and its effects on thermospheric circulation, inSpace Research XII (Berlin, 1972), p. 1157.
citation_journal_title=J. Atmos. Sci.; citation_author=A. H. Manson, J. B. Gregory, D. G. Stephenson; citation_volume=32; citation_publication_date=1973; citation_pages=1682-1682; citation_doi=10.1175/1520-0469(1975)032<1682:WAWMTK>2.0.CO;2; citation_id=CR21
citation_journal_title=Planet. Space Sci.; citation_author=R. A. Vincent, T. J. Stubb; citation_volume=25; citation_publication_date=1977; citation_pages=441-441; citation_doi=10.1016/0032-0633(77)90076-9; citation_id=CR22
citation_journal_title=J. Geophys. Res.; citation_author=C. O. Hines; citation_volume=70; citation_publication_date=1965; citation_pages=177-177; citation_id=CR23
S. P. Zimmermann, A. C. Faire andE. A. Murphy:Wind energy deposition in the upper atmosphere, inSpace Research XII (Berlin, 1972), p. 623.
citation_journal_title=Philos. Trans. R. Soc. London Ser. A; citation_author=J. S. A. Green; citation_volume=271; citation_publication_date=1972; citation_pages=577-577; citation_id=CR25
citation_journal_title=J. Atmos. Terr. Phys.; citation_author=A. H. Manson, J. B. Gregory, D. G. Stephenson; citation_volume=38; citation_publication_date=1976; citation_pages=143-143; citation_doi=10.1016/0021-9169(76)90121-5; citation_id=CR26
citation_journal_title=J. Atmos. Terr. Phys.; citation_author=A. H. Manson, C. E. Meek; citation_volume=42; citation_publication_date=1980; citation_pages=103-103; citation_doi=10.1016/0021-9169(80)90070-7; citation_id=CR27