On seeding equatorial spread F during solstices

• Published in: Geophysical research letters Vol. 37; no. 5
• Main Author: Tsunoda, Roland T.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01-03-2010; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: Alignment; Atmospheric sciences; Convergence; Dipping; Earth sciences; Earth, ocean, space; Equator; equatorial spread F; Exact sciences and technology; Geomagnetic field; Maxima; Migration; Nucleation; Solstices; Spread F; Field line; growth rates; morphology; strength; dip; geomagnetic field; Seeding; Sunset; Alignment; interpretation; Solar terminator; Rayleigh Taylor instability; migration; Spread F; Intertropical convergence zone
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2010GL042576

Interpretation of the morphology of equatorial spread F (ESF) is usually given in terms of factors that modulate the growth rate of the Rayleigh‐Taylor instability. That interpretation is, however, incomplete because only one means for growth‐rate enhancement has been included; that is, the strength of the post‐sunset rise of the F layer could become enhanced, when the solar terminator aligns with geomagnetic field lines. Maxima in ESF occurrence observed near equinoxes seem accountable by this means, but maxima observed near solstices require another source of enhancement. Seasonal migration and latitudinal alignment of the inter‐tropical convergence zone (ITCZ) with the magnetic dip equator is suggested as the missing source, and shown able to fill that void.