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  • 1
    Electronic Resource
    Electronic Resource
    Monitoring air pollution related meteorology using SODAR (1993)
    Springer
    Applied physics 57 (1993), S. 65-82 
    Details
    ISSN: 1432-0649
    Keywords: 92.60.Ek ; 43.85.+f ; 92.60.Sz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hazardous situations in air pollution can many a times be avoided in case short term local weather forecasting of the boundary layer meteorology becomes available. Amongst the various remote sensing techniques, it has been seen that acoustic remote sensing (SODAR) of the lower atmosphere can be employed to determine and predict the atmospheric boundary layer meteorological parameters. In specific, information can be obtained about thermal stratification, mixing height, low level disturbances, depth of the planetary boundary layer, stability classification, wind velocity, wind variances, turbulence parameters, and diffusion characteristics etc. when SODAR is used in conjunction with surface level measurements of the usual meteorological parameters. In the paper a brief description of the acoustic remote sensing technique and a review of the work done during the last two decades to determine the various air quality related meteorological parameters has been given. The methodology to determine mixing height, stability classification and diffusion and dispersion characteristics using mostly the information from the SODAR echograms has also been described. The SODAR echograms obtained at Delhi for the period May 1977 to April 1982 have been processed and analyzed using pattern recognition to determine these parameters. Doppler SODAR information of wind speed and direction have not been treated for the above purpose. Using the Gaussian dispersion model, pollution concentration downwind of a emission source (in the present case it is a cement factory at Nimbahera, Chittorgarh, India) has also been computed with the help of SODAR determined data. It has been found that measured values with the help of high volume sampler conform to the estimated pollution concentration. A peak in the value of the estimated pollution concentration during the fumigation period has also been seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324102
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Tropospheric disturbance of 17–21 December 1974 and its effect on microwave propagation (1977)
    Springer
    Boundary layer meteorology 11 (1977), S. 103-116 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A number of troposphere-monitoring experiments were pressed into service during a large tropospheric disturbance which lasted for several days in December 1974. The experiments operated intensively included a monostatic Sodar system, a satellite radio beacon receiver at very low elevation angles, Meteorological Radiosondes, a 250-kW weather radar, a microwave LOS link and a microbarograph. This multi-pronged campaign yielded very useful results and the correspondences between various observations were striking. The Sodar and microwave link observations were visibly affected only when δN reached a value of about −70 units; however, the satellite beacon observations showed anomalous behaviour even for lower δN values. Rather spectacular coincidences occurred on one night: the large fading (up to 10 db) in the LOS link; highly disturbed conditions displayed in the entire Sodar range; the largest tropospheric effect on the satellite beacon system; and the most active superrefraction of the radar echoes. It was also noticed that these effects are obvious only during nights, while they remain masked or dampened in the sun-lit hours.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221827
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A study of atmospheric structures using sodar in relation to land and sea breezes (1980)
    Springer
    Boundary layer meteorology 18 (1980), S. 361-371 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Simultaneous observations were made by an acoustic sounder and on a meteorological tower during the month of May 1978 at the Atomic Power Station Tarapur. The probing range of the acoustic sounder was 700 m. The meteorological tower could sense wind and temperature at various levels up to a height of 120 m. The site being close to the sea shore, the thermal environment of the lower atmosphere is controlled mostly by land and sea breeze circulations. Thermal convective structures were seen during the daytime and also at night. The frequency of plume formation and the height of the plumes were, however, low during the night. The convective boundary layer in the daytime ranged from 400–500 m while at night it was mostly under 200 m. The observation of thermals at night is explained by the presence of a naturally stable marine layer above 30 m at this site. In the morning hours, winds suddenly change their direction allowing advection of a land breeze which is responsible for the formation of surface-based shear echoes to a height of 200 m during the transition period and for the subsequent development of an elevated layer due to mixing of two different air masses. A marine layer was also seen over Tarapur for a few days during the early evening and night hours. Its height was mostly around 400 m. It may indicate the presence of a subsidence inversion at Tarapur. The need for collection of supporting meteorological data to a height of 500 m by tethered balloon or some other suitable in-situ technique is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119494
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Studies of the Marine Boundary Layer at Tarapur (1986)
    Springer
    Boundary layer meteorology 37 (1986), S. 371-384 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Simultaneous observations were made of the Marine Boundary Layer at Tarapur, a site near Bombay on the sea coast, by acoustic sounder and instrumented tower. The meteorological tower was used to sense wind and temperature at various levels up to a height of 120 m while the acoustic sounder was used to examine the thermal structure of the boundary layer up to a height of 700 m. Data recorded for the year 1982 have been analysed. Analysis of the data shows that while the normal structures of thermal echoes and shear echoes represent the mixing depth of the atmospheric boundary layer, the often observed elevated layers are due to sea breeze reversals with their base giving a measure of the depth of the sea-breeze circulation during the day. A sea breeze has been detected during both spring (March to May) and autumn (October to December) months. The onset times are around 1000 hr during spring months and around noon during the autumn period, the height of development being respectively up to 500 and 350 m. The capability of the sodar to detect the base and thickness of the sea breeze, is clearly revealed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117484
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of structure parameters using sodar (1982)
    Springer
    Boundary layer meteorology 23 (1982), S. 105-114 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The temperature structure parameter at Delhi has been determined from intensity information of sodar observations for a period of one year at a height of 200 m in the planetary boundary layer applying the moisture correction due to Wesely. It is found that mean monthly values of the temperature structure parameter for stable and unstable conditions are quite different during the monsoon months (July to October) but are rather similar during the other months. The refractive index structure parameter values have been calculated for the dry atmosphere (optical) as well as by applying the moisture correction (radio) due to the Sirkis and Ottersten et al. models. It is found that the dry atmospheric values of the parameter are generally lower than the humidity-corrected values. The sodar-measured values of the parameter under dry atmospheric conditions have been examined in relation to the Hufnagel and Tsvang models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00116114
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Studies of the atmospheric stability characteristics during the solar eclipse of February 16, 1980 (1982)
    Springer
    Boundary layer meteorology 24 (1982), S. 415-419 
    Details
    ISSN: 1573-1472
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Observations made with a monostatic sodar and from a 120 m instrumented tower have been used to study the variations in the atmospheric boundary layer at Tarapur (19° 50′ N, 72° 41′ E) during the solar eclipse of February 16, 1980. Atmospheric instability was reduced below normal values during the eclipse but the atmosphere at no time became stable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00120730
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    Paper (German National Licenses)
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