Atmospheric Scale Height as a Modifying Influence on Linear Trend of F-Region Electron Density with Sunspot Number
Abstract
IN the prediction of maximum usable frequencies a linear increase in foF2 with sunspot number is generally assumed for practical purposes1. However, an analysis of maximum usable frequencies, estimated for a sunspot cycle interval from Christchurch ionospheric vertical sounding data obtained during 1947-58, indicated that the trend of twelve-month running average values of foF2 monthly medians with twelve-month running average sunspot number showed significant departures from linearity especially in the daylight hours and above running average sunspot number 170 at the 1957-58 sunspot maximum. Chun-Ming Huang2 has observed a similar marked departure from linear trend at the 1957-58 maximum in an analysis of vertical sounding stations in the Western Pacific area, the time of onset relative to sunspot number varying with time of day and station latitude.
- Publication:
-
Nature
- Pub Date:
- November 1961
- DOI:
- 10.1038/192542a0
- Bibcode:
- 1961Natur.192..542B