English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Swept-frequency (1-10 MHz) ionosonde\udmeasurements were made at Helston, Cornwall (50°06'N, 5°18'W)\udduring the total solar eclipse on August 11, 1999. Soundings were made every\udthree minutes. We present a method for estimating the percentage of the ionising\udsolar radiation which remains unobscured at any time during the eclipse by\udcomparing the variation of the ionospheric E-layer with the behaviour of the\udlayer during a control day. Application to the ionosonde date for 11 August,\ud1999, shows that the flux of solar ionising radiation fell to a minimum of\ud25±2% of the value before and after the eclipse. For comparison, the same\udtechnique was also applied to measurements made during the total solar eclipse\udof 9 July, 1945, at Sörmjöle (63°68'N, 20°20'E)\udand yielded a corresponding minimum of 16±2%. Therefore the method can detect\udvariations in the fraction of solar emissions that originate from the unobscured\udcorona and chromosphere. We discuss the differences between these two eclipses\udin terms of the nature of the eclipse, short-term fluctuations, the sunspot\udcycle and the recently-discovered long-term change in the coronal magnetic\udfield.  <b>Key words: </b>Ionosphere (solar radiation and cosmic ray\udeffects) - Radio science (ionospheric physics) - Solar physics, astrophysics,\udand astronomy (corona and transition region

Ionospheric measurements of relative coronal brightness during the total solar eclipses of 11 August, 1999 and 9 July, 1945