The Solar Radius at 37 GHz Through Cycles 22 to 24

To better understand the influence of the activity cycle on the solar atmosphere, we report the time variation of the radius observed at 37 GHz ( λ = 8.1  mm ) obtained by the Metsähovi Radio Observatory (MRO) through Solar Cycles 22 to 24 (1989 – 2015). Almost 5800 maps were analyzed, however, due...

Full description

Saved in:
Bibliographic Details
Published in:Solar physics 2019-12, Vol.294 (12), Article 175
Main Authors: Selhorst, Caius L., Kallunki, Juha, Giménez de Castro, C. Guillermo, Valio, Adriana, Costa, Joaquim E. R.
Format: Article
Language:English
Subjects:
Astrophysics and Astroparticles
Atmospheric Sciences
Correlation
Physics
Physics and Astronomy
Solar atmosphere
Solar cycle
Solar flux
Solar physics
Space Exploration and Astronautics
Space Sciences (including Extraterrestrial Physics
Wavelengths
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:To better understand the influence of the activity cycle on the solar atmosphere, we report the time variation of the radius observed at 37 GHz ( λ = 8.1  mm ) obtained by the Metsähovi Radio Observatory (MRO) through Solar Cycles 22 to 24 (1989 – 2015). Almost 5800 maps were analyzed, however, due to instrumental setup changes the dataset showed four distinct behaviors, which required a normalization process to allow for the whole interval analysis. When the whole period was considered, the results showed a positive correlation index of 0.17 between the monthly means of the solar radius at 37 GHz and solar flux obtained at 10.7 cm (F10.7). This correlation index increased to 0.44, when only the data obtained during the last period without instrumental changes were considered (1999 – 2015). The solar radius correlation with the solar cycle agrees with the previous results obtained at mm/cm wavelengths (17 and 48 GHz), nevertheless, this result is the opposite of that reported at submillimeter wavelengths (212 and 405 GHz).
ISSN:0038-0938
1573-093X
DOI:10.1007/s11207-019-1568-6