NOPR Collection:

A Comparative Study of Nighttime Electron Density Profiles & Observed Absorption Data

Sat, 01 Feb 1986 00:00:00 GMT

Title: A Comparative Study of Nighttime Electron Density Profiles & Observed Absorption Data Authors: Acharya, B L; Rai, R K Abstract: A comparative study of nighttime electron density profiles and observed absorption data over Udaipur (24 35' N) has been made for low and high solar activity periods. Some of the profiles are found to be in good agreement with the observed absorption data in low solar' activity period. However, during high solar activity, the computed absorption is found to differ from the observed one. Page(s): 32-34

Differential Absorption Measurements of Atmospheric Minor Constituents with a Laser - Water Vapour

Sat, 01 Feb 1986 00:00:00 GMT

Title: Differential Absorption Measurements of Atmospheric Minor Constituents with a Laser - Water Vapour Authors: Jain, S L; Arya, B C; Nakra, D R; Saha, A K Abstract: An experimental system using a CO₂ laser, for estimation of atmospheric minor constituents by the differential absorption technique (DIAL), is described. A pair of CO₂ laser lines in the 9 to 11 micron band are chosen one on the absorption line of a molecule under investigation and the other off this line where no absorption is expected. The laser beam is reflected back from a 7.5cm retroreflector and is received at the transmitter site. The differential absorption over the path length is used to estimate the integrated gas concentration. Water vapour measurements over a 150-m path under various conditions are described Page(s): 29-31

Acoustic Sounding of Coastal Boundary Layer

Sat, 01 Feb 1986 00:00:00 GMT

Title: Acoustic Sounding of Coastal Boundary Layer Authors: Rao, M Purnachandra; Kumar, A Raghu; Murthy, J S R; Rao, A S Mohana; Rao, C Poornachandra Abstract: The acoustic sounder data obtained during the period June 1980-May 1981 have been analyzed with special reference to sea breeze. Simultaneous measurements of sea breeze using pilot balloon ascents and acoustic sounder were made on eight days in May 1981. A reasonably good agreement has been obtained between the acoustic sounder estimation of the depth of the sea breeze and the height of the onshore flow as deduced from hourly balloon ascents. The height variations of the elevated layer on the sounder record were also reflected in the flow patterns. The development of the elevated layer associated with the sea breeze circulation was delayed due to the limited vertical extent of sea breeze in the first few hours after the onset. The alternation or land and sea breeze more than once during a day in the observational period was partly due to the oscillatory behaviour of a trough of low pressure inland. The monthly charts prepared for the 12 months showed a definite seasonal variation in the diurnal behaviour of the coastal boundary layer at Visakhapatnam. Page(s): 21-28

Diurnal Variations of Annual & Semi-annual Periodicities in-IEC at Lunping

Sat, 01 Feb 1986 00:00:00 GMT

Title: Diurnal Variations of Annual & Semi-annual Periodicities in-IEC at Lunping Authors: Bhuyan, P K; Tyagi, Tuhi Ram Abstract: The diurnal variations of the annual and semi-annual periodicities in the F-region of the ionosphere over Lunping are investigated by analyzing the monthly mean values of ionospheric electron content (IEC) for a period of three consecutive years representing low, medium and high sunspot activity. Significant solar cycle variations in both amplitude and phase have been observed. The diurnal maximum in IEC occurs progressively later with increase in solar activity. The phase of the annual component shifts from winter in solar minimum to late autumn in solar maximum, whereas the phase of the semi-annual maxima is only in equinox conforming to the global behaviour. The variations are mostly explained in terms of the E × 8 drifts and changes in the atmospheric composition. Page(s): 17-20