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

Space Weather Challenge & Forecasting Implications Of Rossby Waves

Graph depicting solar magnetic weather
Tuesday, March 31, 2020

Rossby waves arise in thin layers within fluid regions of stars and planets. These global wave-like patterns occur due to the variation in Coriolis forces with latitude. In the past several years observational evidence has indicated that there are also Rossby waves in the Sun.

Sun-Like Stars Shed Light on Solar Climate Forcing

Seasonally averaged data for the CaII“S-index” and for the average magnitudes of the Strömgrenbplusy filters
Tuesday, January 7, 2020

Recently published, precise stellar photometry of 72 Sun-like stars obtained at the Fairborn Observatory between 1993 and 2017 is used to set limits on the solar forcing of Earth’s atmosphere of ±4.5 W m−2 since 1750.

Temperature in a long-lived cavity

Graphic depicting Angstrom images of the cavity
Wednesday, December 11, 2019

Gibson et al. have analyzed a long-lived cavity observed from 17 March 2012 to 21 March 2012. For this cavity we applied a differential emission measure method to obtain both a temperature distribution and a value of the average temperature during all five observational days.

Waldmeier Effect in Stellar Cycles

Graph depicting the second Waldmeier effect-WE2
Tuesday, October 8, 2019

One of the most robust features of the solar magnetic cycle is that the stronger cycles rise faster than the weaker ones. This is popularly known as the Waldmeier Effect, which is known for more than 100 years.

Simulating the solar corona in the forbidden and permitted lines with forward modeling I: Saturated and unsaturated Hanle regimes

Graphic depicting Linear polarization azimuth
Thursday, October 3, 2019

The magnetic field in the corona is important for understanding solar activity. Linear polarization measurements inforbidden lines in the visible/IR provide information about coronal magnetic direction and topology.

The eruption of a prominence carrying coronal flux rope forward synthesis of the magnetic field strength measurement by COSMOS

(a) The inferred line-of-sight (LOS) magnetic field B_LOS obtained from the forward synthesis of the circular polarization signal from the MHD model data at a time during the quasi-static phase of the flux rope; (b) The same as (a) but only show the pixels of the measured B_LOS with sufficient signal to noise ratio; (c) The axial field strength in the mid cross-section of the flux rope; (d) The 3D field lines of the coronal magnetic field as view
Tuesday, November 13, 2018

From a magnetohydrodynamic (MHD) simulation of the eruption of a prominence hosting coronal flux rope, Yuhong Fan and others carry out forward synthesis of the circular polarization signal (Stokes V signal) of the FeXIII emission line at 1074.7 nm produced by the MHD model.

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.

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.

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.