HF Doppler observations associated with spread F

This paper discusses HF Doppler spectrum observations at mid-latitudes when spread F was observed on local ionograms. The data indicate that Doppler broadening is related to spread F (they both commence simultaneously). The results can be simulated by using different ionospheric models. Calculations show that a rippled contour can cause HF Doppler broadening and range spreading on ionograms if the structure is traveling horizontally. Although this mechanism can lead to HF Doppler broadening, scattering at 4.5 and 7.5 MHz in an anisotropic medium from near overhead can also explain the experimental results. The observation of aspect-sensitive scatter does, however, depend critically on the statistical description of the irregularity spectrum. It is suggested that an experiment designed to measure the Doppler shift as a function of zenith angle may enable some of the current ambiguities associated with spread F to be eliminated.

[1]  E. Essex,et al.  Observations of mid-latitude sporadic E using the HF Doppler technique , 1979 .

[2]  K. Joyner,et al.  Scattering from F.region irregularities at 4.5 and 7.5 MHz , 1975 .

[3]  P. Rao,et al.  HF phased array observations of heater-induced spread-F , 1974 .

[4]  R. S. Germain,et al.  The angular distribution of spread F returns from an artificially modified ionosphere , 1974 .

[5]  P. L. Dyson,et al.  In situ measurements of the spectral characteristics of F region ionospheric irregularities , 1974 .

[6]  K. Yeh,et al.  A theory of scattering from irregularities in a magneto-ionic medium. , 1972 .

[7]  H. Bates.  The aspect sensitivity of spread-F irregularities , 1971 .

[8]  G. King.  Spread-F on ionograms , 1970 .

[9]  D. M. Baker.  A review of some ionospheric studies : based on a high-frequncy doppeler technique , 1968 .

[10]  J. R. Herman,et al.  Spread F and ionospheric F‐region irregularities , 1966 .

[11]  B. Clemesha.  An investigation of the irregularities in the F-region associated with equatorial type spread-F , 1964 .

[12]  K. Bowles.  Radio Wave Scattering in the Ionosphere , 1964 .

[13]  E. M. Swenson.  Preliminary Results of Observations of Aspect-sensitive Reflections from Irregularities in the F Region , 1964 .

[14]  M. Pitteway,et al.  A waveguide interpretation of “Temperate‐latitude spread F” on equatorial ionograms , 1961 .

[15]  R. Cohen,et al.  The interpretation and synthesis of certain spread‐F configurations appearing on equatorial ionograms , 1961 .

[16]  H. Booker,et al.  A local reduction of F‐region ionization due to missile transit , 1961 .

[17]  R. Cohen,et al.  On the nature of equatorial spread F , 1961 .

[18]  G. G. Bowman.  Further studies of “Spread-F” at Brisbane-II interpretation , 1960 .

[19]  G. G. Bowman.  Further studies of “Spread-F” at Brisbane-I experimental , 1960 .

[20]  O. Villard,et al.  Regularly‐observable aspect‐sensitive radio reflections from ionization aligned with the Earth's magnetic field and located within the ionospheric layers at middle latitudes , 1955 .