Ionogram signatures of large‐scale wave structure and their relation to equatorial spread F

[1] Observations of signatures of the large-scale wave structure (LSWS) and subsequent development of equatorial spread F (ESF) by using data from a newly installed digital ionosonde at Trivandrum (8.5°N; 77°E; 0.5°N magnetic dip latitude) are presented. The LSWS signatures are observed using the ionograms with echo directions. The ‘satellite’ traces are shown as echoes from oblique directions, when an upwelling (associated with LSWS) is not directly over the ionosonde location. When an upwelling is centered overhead, and the radius of curvature of the isodensity contours matches the height of reflection, signals from various directions can add in phase to enhance the ionospheric reflection coefficient, and produce another ionogram signature, referred to as multireflected echoes (MREs). It is also shown that the generation of ESF is related to the presence of LSWS. The skymaps also show the presence of small-scale wave structures in the bottomsideFregion. The investigation also indicates that the range spread F (RSF) occurs because of the reflections from the embedded smaller-scale structures within the large-scale upwelling.

[1]  Bodo W. Reinisch,et al.  Relationship between strong range spread F and ionospheric scintillations observed in Hainan from 2003 to 2007 , 2011 .

[2]  Mamoru Yamamoto,et al.  On large‐scale wave structure and equatorial spread F without a post‐sunset rise of the F layer , 2010 .

[3]  M. Yamamoto,et al.  First observations of large‐scale wave structure and equatorial spread F using CERTO radio beacon on the C/NOFS satellite , 2009 .

[4]  R. Tsunoda.  Multi‐reflected echoes: Another ionogram signature of large‐scale wave structure , 2009 .

[5]  A. Patra,et al.  Equatorial Spread F structures and associated airglow intensity variations observed over Gadanki , 2008 .

[6]  R. Tsunoda.  Satellite traces: An ionogram signature for large‐scale wave structure and a precursor for equatorial spread F , 2008 .

[7]  R. Tsunoda.  On the enigma of day‐to‐day variability in equatorial spread F , 2005 .

[8]  Bodo W. Reinisch,et al.  Multistation digisonde observations of equatorial spread F in South America , 2004 .

[9]  E. Kherani,et al.  Equatorial rising structure in nighttime upper E-region: a manifestation of electrodynamical coupling of spread F , 2002 .

[10]  A. Patra,et al.  Interaction of two long‐wavelength modes in the nonlinear numerical simulation model of equatorial spread F , 2001 .

[11]  Bodo W. Reinisch,et al.  Vertical electron content from ionograms in real time , 2001 .

[12]  Bodo W. Reinisch,et al.  Ionospheric drift measurements with ionosondes , 1998 .

[13]  F. S. Johnson,et al.  Gravity wave seeding of equatorial plasma bubbles , 1997 .

[14]  R. Sekar,et al.  A case study on the evolution of equatorial spread-F by a nonlinear numerical model using the results from a set of coordinated measurements , 1997 .

[15]  J. Sastri.  Patchy occurrence of equatorial spread-F , 1985 .

[16]  M. Larsen,et al.  Gravity wave initiation of equatorial spread F: A case study , 1981 .

[17]  R. Tsunoda,et al.  On the generation and growth of equatorial backscatter plumes 1. Wave structure in the bottomside F layer , 1981 .

[18]  I. Batista,et al.  Some characteristics of spread F at the magnetic equatorial station Fortaleza , 1980 .

[19]  R. Tsunoda,et al.  On the spatial relationship of 1-meter equatorial spread-F irregularities and depletions in total electron content , 1979 .

[20]  J. Owen,et al.  ALTAIR: an incoherent scatter radar for equatorial spread-F studies. Topical report 1 June 1977-1 January 1978 , 1979 .

[21]  R. Rastogi.  Equatorial range spreadF and high multiple echoes from theF region , 1977 .

[22]  Ronald F. Woodman,et al.  Radar observations of F region equatorial irregularities , 1976 .

[23]  J. Röttger.  Wave-like structures of large-scale equatorial spread-F irregularities , 1973 .

[24]  A. Lyon,et al.  Equatorial spread-F at Ibadan, Nigeria , 1961 .

[25]  A. Patra,et al.  On the importance of wave‐like structures in the occurrence of equatorial plasma bubbles: A case study , 2012 .

[26]  Bodo W. Reinisch,et al.  Deducing topside profiles and total electron content from bottomside ionograms , 2001 .

[27]  R. Tsunoda.  Time evolution and dynamics of equatorial backscatter plumes 1. Growth phase , 1981 .