scholarly journals Ionospheric Absorption Studies Based on Cosmic Noise Data at 28·6 MHz at Bangalore

1967 ◽  
Vol 20 (4) ◽  
pp. 455 ◽  
Author(s):  
M Krishnamurthi ◽  
SBS Subrahmanya Sarma
Keyword(s):  
Local Time ◽  
Seasonal Variations ◽  
Noise Intensity ◽  
Cosmic Radio ◽  
Narrow Beam ◽  
Radio Noise ◽  
Ionospheric Absorption ◽  
Absorption Studies ◽  
Noise Data ◽  
Cosmic Noise

Using a. fa.irly narrow beam antenna (10��5 by 16��5), cosmic radio noise at 28�6 MHz has been continuously recorded during the years 1962-64. The data between midnight and 06 hr local time were used to determine the "unabsorbed cosmic noise intensity" for different sidereal times. Based on this, the total ionospheric absorption at this frequency was computed for the rest of the day. Diurnal and seasonal variations are discussed.

scholarly journals Multi beam observations of cosmic radio noise using a VHF radar with beam forming by a Butler matrix

2011 ◽  
Vol 9 ◽  
pp. 349-357 ◽  
Author(s):  
T. Renkwitz ◽  
W. Singer ◽  
R. Latteck ◽  
M. Rapp
Keyword(s):  
Middle Atmosphere ◽  
Beam Forming ◽  
Cosmic Radio ◽  
Radio Noise ◽  
Spatiotemporal Resolution ◽  
Vhf Radar ◽  
Butler Matrix ◽  
The North ◽  
Noise Absorption ◽  
Cosmic Noise

Abstract. The Leibniz-Institute of Atmospheric Physics (IAP) in Kühlungsborn started to install a new MST radar on the North-Norwegian island Andøya (69.30° N, 16.04° E) in 2009. The new Middle Atmosphere Alomar Radar System (MAARSY) replaces the previous ALWIN radar which has been successfully operated for more than 10 years. The MAARSY radar provides increased temporal and spatial resolution combined with a flexible sequential point-to-point steering of the radar beam. To increase the spatiotemporal resolution of the observations a 16-port Butler matrix has been built and implemented to the radar. In conjunction with 64 Yagi antennas of the former ALWIN antenna array the Butler matrix simultaneously provides 16 individual beams. The beam forming capability of the Butler matrix arrangement has been verified observing the galactic cosmic radio noise of the supernova remnant Cassiopeia A. Furthermore, this multi beam configuration has been used in passive experiments to estimate the cosmic noise absorption at 53.5 MHz during events of enhanced solar and geomagnetic activity as indicators for enhanced ionization at altitudes below 90 km. These observations are well correlated with simultaneous observations of corresponding beams of the co-located imaging riometer AIRIS (69.14° N, 16.02° E) at 38.2 MHz. In addition, enhanced cosmic noise absorption goes along with enhanced electron densities at altitudes below about 90 km as observed with the co-located Saura MF radar using differential absorption and differential phase measurements.

scholarly journals Impulsive, quasi-periodic variations in ionospheric absorption of cosmic radio noise.

1979 ◽  
Vol 31 (6) ◽  
pp. 585-597 ◽  
Author(s):  
T. J. ROSENBERG ◽  
L. J. LANZEROTTI ◽  
C. G. MACLENNAN ◽  
C. EVANS
Keyword(s):  
Cosmic Radio ◽  
Radio Noise ◽  
Ionospheric Absorption

scholarly journals Short Communications: A Method of Obtaining the Mean Electron Collision Frequencies in the F2 Layer from Cosmic Noise Absorption Studies

1967 ◽  
Vol 20 (4) ◽  
pp. 463 ◽  
Author(s):  
M Krishnamurthi ◽  
SBS Subrahmanya Sarma
Keyword(s):  
Electron Collision ◽  
Topside Ionosphere ◽  
Present Issue ◽  
Noise Absorption ◽  
Ionospheric Absorption ◽  
Absorption Studies ◽  
Spread F ◽  
The Mean ◽  
Cosmic Noise

In the previous paper (pp. 455-62 of the present issue) the authors have shown that the total ionospheric absorption of cosmic noise at 28�6 MHz can be expressed as a sum of three contributions: from the F2 layer (including topside ionosphere), from the D and E layers, and from abnormal phenomena such as spread-F; and can be given by the expression

scholarly journals The first discovery of point sources

1959 ◽  
Vol 9 ◽  
pp. 295-296
Author(s):  
J. S. Hey
Keyword(s):  
Low Noise ◽  
Point Sources ◽  
Noise Factor ◽  
Expected Improvement ◽  
Cosmic Radio ◽  
Radio Noise ◽  
Theoretical Physicist ◽  
Cosmic Noise

The investigations into cosmic radio noise that I made with J. W. Phillips and S. J. Parsons arose from operational studies of the performance of radar equipment at about 5-m wavelength in 1944–45. To obtain greater detection ranges, preamplifier stages of low-noise factor were being tested, but they did not result in the expected improvement in radar performance. J. M. C. Scott, a theoretical physicist now at Cambridge, suggested to me that the limitation in effective noise factor might be attributable to cosmic noise, about which something was already known from the work of Jansky and Reber.

scholarly journals Sudden Cosmic Noise Absorption at 29 Mc/s

1962 ◽  
Vol 15 (1) ◽  
pp. 20 ◽  
Author(s):  
M Krishnamurthi ◽  
G Sivarama Sastry ◽  
T Seshagiri Rao
Keyword(s):  
Solar Flare ◽  
Radio Emission ◽  
Solar Flares ◽  
Initial Conditions ◽  
Cosmic Radio ◽  
Radio Noise ◽  
Terrestrial Atmosphere ◽  
Noise Absorption ◽  
Cosmic Noise

Cosmic radio noise observations at 29 Mc/s made at Hyderabad, India (17� 26' N., 78� 27' E.), have been compared with solar flare data for the year 1958. For flares of importance 3 or 3�, there is a correlation of 84% with regard to related effects observed in the cosmic noise records. These effects are either enhanced radio emission or SCNA's. Particular study of the 9 SCNA's observed during the year and comparison with results of Bhonsle working at Ahmedabad, India (23� 02' N., 72� 38' E.), reveal that (a) even in the case of intense flares initial conditions in the terrestrial atmosphere govern the production and maintenance of an SCNA, and (b) therefore, at least at frequencies above 25 Mc/s, SCNA's cannot be used for patrolling even intense solar flares.

scholarly journals Cosmic Radio Noise Absorption and Hydrogen Emission in the Auroral Substorm

1973 ◽  
Vol 26 (2) ◽  
pp. 225 ◽  
Author(s):  
BP Kilfoyle ◽  
F Jacka
Keyword(s):  
Cosmic Radio ◽  
Radio Noise ◽  
Hydrogen Emission ◽  
Noise Absorption ◽  
Ionospheric Absorption ◽  
Auroral Substorm

From a study of records from Mawson, Kiruna, and Murmansk it is shown that slowly varying ionospheric absorption (SVIA) and HP emission are characteristic of the region behind the midnight poleward bulge of the auroral substorm, in accord with the model of Akasofu (1968).

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