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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Meteorology and atmospheric physics 64 (1997), S. 107-121 
    ISSN: 1436-5065
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Summary An ozone mini-hole is a region of strongly depleted column total ozone amounts, associated with the growth of synoptic-scale wave disturbances. Their formation is illustrated here using a sequence of idealised model experiments. Simplified barotropic dynamics are used to drive an ozone tracer advection model on an f-plane representing a hemisphere. Firstly, the Contour Dynamics method is used to integrate the barotropic vorticity equation. Vorticity contours are initialised to simulate typical planetary wave structures and the developing wind field advects components of the ozone model. The vertical profiles of ozone mixing ratio are represented by simple linear functions, separated by a tropopause height field and capped by an upper model boundary. Integrating these profiles thus yields a total column ozone field which is closely dependent on tropopause height. In addition to horizontal advection, a vertical motion parametrisation is included, based on a quasi-geostrophic theory for tropopause displacement. The model is also used to simulate the formation of an actual mini-hole which occurred over northern Europe. Here, observed fields of vorticity, ozone and tropopause height are employed and the system integrated using a pseudo-spectral method. The mini-hole is successfully simulated, despite the simple model dynamics. The results demonstrate the correlation between column total ozone and the tropopause height and confirm the crucial role played by vertical air motions and by the meridional gradients of mid-stratospheric ozone mixing ratios for the formation of ozone mini-holes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract  A singular value decomposition (SVD) is used to calculate SVD-selected fields of ozone and geopotential, which exhibit maximum covariance, from the observed zonally asymmetric total ozone field and that of the three-dimensional geopotential field thus leaving almost purely dynamical induced variations in the remaining ozone field. This procedure was applied to Total Ozone Mapping Spectrometer data (TOMS) and to geopotential values from the National Centers for Environmental Prediction in the boreal mid-latitudes in the winter months of 1979–1992. Intraseasonal variability (December–February) and trend-eliminated interannual winter mean variability of total ozone and geopotential are analyzed. The first four modes of SVD analysis explain more than 70% of the covariance for the intraseasonal variability and more than 80% of that for the interannual variability. The vertical structure of geopotential regression maps reveals a clear wave-1 pattern for modes one and two and a wave-2 pattern for modes three and four. These patterns show differently but generally westward tilted phases and are more complex at heights below 70 hPa. Further a linear transport model of a conservative tracer was applied to each individual geopotential mode found by the SVD analysis in connection with an observed height and latitude dependent zonal mean ozone distribution. The model results of total ozone reproduce the spatial patterns of the SVD-selected total ozone field quite well whereas their magnitudes are variously underestimated. This method allows us to assess the vertical distribution of the contribution of single modes to the total ozone variability. Maximum contributions are found between 150 and 70 hPa. Smaller amplitude maxima are found around 10 hPa, which result from contributions of horizontal advection of ozone alone. These results reflect an expected dynamical link between the variability of the zonally asymmetric parts of geopotential and ozone.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 1997-01-01
    Print ISSN: 0177-7971
    Electronic ISSN: 1436-5065
    Topics: Geography , Physics
    Published by Springer
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  • 4
    Publication Date: 1995-09-01
    Print ISSN: 0022-4928
    Electronic ISSN: 1520-0469
    Topics: Geography , Geosciences , Physics
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  • 5
    Publication Date: 1998-10-29
    Print ISSN: 0930-7575
    Electronic ISSN: 1432-0894
    Topics: Geosciences , Physics
    Published by Springer
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  • 6
    Publication Date: 2016-06-07
    Description: Daily zonal wind data of the four pre-MAP-winters 1978/79 to 1981/82 obtained over Central Europe and Eastern Europe by the radar meteor method were studied. Available temperature and satellite radiance data of the middle and upper stratosphere were used for comparison, as well as wind data from Canada. The existence or nonexistence of coupling between the observed large scale zonal wind disturbances in the upper mesopause region (90 to 100 km) and corresponding events in the stratosphere are discussed.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions Middle Atmosphere Program. Handbook for MAP, Vol. 10; p 91-95
    Format: application/pdf
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  • 7
    Publication Date: 2013-08-31
    Description: Daily values of sunspot number and solar radio emission at 10.7 cm wavelength show a well known strong modulation with a period of 27 days, the Sun's rotation period. Recent satellite measurements revealed the same modulation of the ultraviolet irradiance at wavelength below 300 nm. These UV variations can influence the thermal heating of the ozone layer by altering the chemical composition. Therefore, one can also expect a corresponding variation in the middle atmosphere of the semi-diurnal tide, which is thermally excited essentially by absorption of UV between 200 and 370 nm in the upper ozone layer. Results of radar meteor wind measurements were used to detect a presumable very weak 27 day modulation within the natural and artificial noise of the daily values of the semi-diurnal wind amplitude. The summer period was chosen because of its relatively steady conditions and the maximum amplitudes during the year. The results of this investigation are given and discussed.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 25; p 119-120
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  • 8
    Publication Date: 2013-08-31
    Description: The solar cycle dependence of wind parameters below 100 km on the basis of long term continuous ionospheric drift measurements in the low frequency range is discussed. For the meridional prevailing wind no significant variation was found. The same comparison as for winter was done for summer where the previous investigations gave no correlation. Now the radar meteor wind measurement values, too, showed a significant negative correlation of the zonal prevailing wind with solar activity for the years 1976 to 1983. The ionospheric drift measurement results of Collm have the same tendency but a larger dispersion due to the lower accuracy of the harmonic analysis because of the shorter daily measuring interval in summer. Continuous wind observations in the upper mesopause region over more than 20 years revealed distinct long term variations, the origin of which cannot be explained with the present knowledge.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 25; p 58-61
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  • 9
    Publication Date: 2013-08-31
    Description: Temporal variations of prevailing winds at 90 to 100 km obtained from measurements carried out in winter 1983 to 1984 at three sites in the USSR and two sites in East Germany are reported. These variations are compared with those of the thermal stratospheric regime. Measurements were carried out using the drifts D2 method (meteor wind radar) and the D1 method (ionospheric drifts). Temporal variations of zonal and meridional prevailing wind components for all the sites are given. Also presented are zonal wind data obtained using the partial reflection wind radar. Wind velocity values were obtained by averaging data recorded at between 105 and 91 km altitude. Wind velocity data averaged in such a way can be related to about the same height interval to which the data obtained by the meteor radar and ionospheric methods at other sites, i.e., the mean height of the meteor zone (about 95 km). The results presented show that there are significant fluctuations about the seasonal course of both zonal and meridional prevailing winds.
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions, Middle Atmosphere Program. Handbook for MAP, Volume 25; p 66-69
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  • 10
    Publication Date: 2014-10-10
    Description: A sinusoisal least squares fit over the entire data of 1 to 6 May 1982 was computed. The results are shown. Wind results refere to an average height of 95 km (no height determination). The wind results correspond, in general, to the average behavior of early May. The zonal prevailing west wind, however, is stronger than the term mean value (-5 m/s). Also, the amplitude of the semidiurnal idal wind is larger (mean value 1977 to 1983: 8 m/s).
    Keywords: GEOPHYSICS
    Type: International Council of Scientific Unions Middle Atmosphere Program. Handbook for MAP, Vol. 17; p 46
    Format: text
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