Long-Term Solar Variability

Overview and Research Goal

The long-term variability of solar magnetism describes changes at the Sun that take place over the course of weeks, months, years, decades, and even centuries or longer. Such changes have profound consequences for the Earth's space environment, and, to a lesser extent, for its climate system. The origins and impacts of these changes have deep relevance to related variability in stars and stellar systems.

The research goal of LSV is to promote understanding of long-term solar variability from the Sun's interior out to the heliosphere. We will work with the community to achieve this using a combination of observations, theory, and numerical models to probe outstanding questions of magnetic dynamos, of convection and flows, of magnetic flux emergence and sunspots, of the evolution of the Sun's corona and the heliosphere, and of solar cycle variation.

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Research Highlights

Solar Prominences: Theory and models (Fleshing out the magnetic skeleton)

Painting the dips of a magnetic skeleton results in sheet-like prominences
Friday, August 24, 2018

Magnetic fields suspend the relatively cool material of solar prominences in an otherwise hot corona. A comprehensive understanding of solar prominences ultimately requires complex and dynamic models, constrained and validated by observations spanning the solar atmosphere.

Long-lasting response of the global thermosphere and ionosphere to the 21 August 2017 solar eclipse

Long-lasting response of the global thermosphere and ionosphere
Sunday, August 5, 2018

Explains Wenbin Wang and others, previous studies have been devoted to examining the ionosphere and thermosphere response during the solar eclipse, but the post-eclipse response of the global ionosphere and thermosphere has not previously been well quantified.

Evolution of the Global Solar Magnetic Field over 4 Solar Cycles: Use of the McIntosh Archive

Butterfly-type plots of all of the McA data
Thursday, July 26, 2018

The McIntosh Archive consists of a set of hand-drawn solar Carrington maps created by Patrick McIntosh from 1964 to 2009. McIntosh used mainly H, He-I 10830Å and photospheric magnetic measurements from both ground-based and NASA satellite observations.

Solar physics from unconventional viewpoints

An overview of interesting vantage points, highlighting previous extra-Sun-Earth-line (extra-SEL) missions
Thursday, July 26, 2018

We explore new opportunities for solar physics that could be realized by future missions providing sustained observations from vantage points away from the Sun-Earth line.

Magnetic Buoyancy and Rotational Instabilities in the Tachocline

Instability domains in low and middle latitudes
Wednesday, January 17, 2018

Peter Gilman presents results from an analytical model for magnetic buoyancy and ro­tational instabilities in a full spherical shell tachocline that includes rotation. differential rotation close to that observed helioseismicly, and toroidal field.

Origins of the Ambient Solar Wind: Implication for Space Weather

Carrington rotation stack plots
Thursday, September 7, 2017

The Sun’s outer atmosphere is heated to temperatures of millions of degrees, and solar plasma flows out into interplanetary space at supersonic speeds. This paper reviews our current understanding of these interrelated problems: coronal heating and the acceleration of the ambient solar wind.

MHD Simulations of the Eruption of Coronal Flux Ropes under Coronal Streamers

MHD simulations
Thursday, July 20, 2017

Using three-dimensional magnetohydrodynamic (MHD) simulations, we investigate the eruption of coronal flux ropes underlying coronal streamers and the development of a prominence eruption.

Solar Cycle Variability Induced by Title Angle Scatter in a Babcockl-Leighton Solar Dynamo Model

Variability in sunspot number (SSN) in STABLE dynamo simulations of the solar cycle using the observed random scatter in sunspot pair tilt angle of 15 degrees. (a) 19 magnetic cycles are highlighted with red and blue representing the northern and southern hemispheres respectively. Red shaded areas indicate periods when the SSN in the north exceeds that in the south and blue shaded areas indicate the opposite. (b) Long-term SSN variability in the same simulation, exhibiting extended periods of low and high a
Saturday, April 15, 2017

We present results from a three-dimensional Babcock–Leighton dynamo model that is sustained by the explicit emergence and dispersal of bipolar magnetic regions (BMRs). On average, each BMR has a systematic tilt given by Joy’s law.

A Theoretical Study of the Build-up of the Sun's Polar Magnetic Field by Using a 3D Kinematic Dynamo Model

Time evolution of two bipolar magnetic regions (BMRs)
Monday, January 9, 2017

We develop a three-dimensional kinematic self-sustaining model of the solar dynamo in which the poloidal field generation is from tilted bipolar sunspot pairs placed on the solar surface above regions of strong toroidal field by using the SpotMaker algorithm and then the transport of this poloida

Beyond sunspots: Studies using the McIntosh Archive of global solar magnetic

Thursday, December 15, 2016

In 1964 (Solar Cycle 20; SC 20), Patrick McIntosh began creating hand-drawn synoptic maps of solar magnetic features, based on H-alpha images.