Open AccessSimultaneous radar observations of meter‐scale F region irregularities at and off the magnetic equator over India
Author(s) -
Patra A. K.,
Tiwari D.,
Sripathi S.,
Rao P. B.,
Sridharan R.,
Devasia C. V.,
Viswanathan K. S.,
Subbarao K. S. V.,
Sekar R.,
Kherani E. A.
Publication year - 2005
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2004ja010565
Subject(s) - equator , longitude , radar , earth's magnetic field , geology , latitude , doppler effect , magnetic dip , geodesy , range (aeronautics) , geophysics , physics , magnetic field , materials science , astronomy , quantum mechanics , telecommunications , computer science , composite material
Simultaneous observations of equatorial spread F irregularities made with an 18 MHz radar from Trivandrum, located at the geomagnetic equator, and a 53 MHz radar from Gadanki, located at a magnetic latitude of 6.5°N, corresponding to nearly the same longitude zone, are presented. The observations correspond to 8.3 and 2.8 m irregularities, respectively. The spread F irregularities at both the locations are found to occur nearly at the same time but are observed for longer duration at Gadanki than at Trivandrum. The spread F structures as observed in the intensity maps corresponding to Gadanki are characterized by multiple periodic plumes in contrast to a limited number of plumes observed over Trivandrum. The Doppler velocities associated with these irregularities corresponding to Trivandrum are in the range of −100–150 m s −1 , whereas they are in the range of −100–250 m s −1 at Gadanki. Further, the fluctuating velocity fields are much stronger in the Gadanki observations than in the Trivandrum observations. Remarkably, the spectral widths are <100 m s −1 in Trivandrum observations in contrast to those observed at Gadanki with values as high as 300 m s −1 . The observations are compared with those made elsewhere and are discussed in the light of current understanding of the meter‐scale irregularities responsible for the radar backscatter.