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TRANSCRIPT
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Andrés Muñoz-Jaramillo
Harvard-Smithsonian Center for Astrophysics University Corporation for Atmospheric Research
Department of Physics and Astronomy, University of Utah
Implications of Changes to the SSN for Solar Dynamo Studies & Climate Change
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Disclaimer
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
• For the sake of explanation I have made many simplifications and left out a fair amount of details on the work of others.
• This talk is not a critique of said works, but an attempt to assess the impact that changes in the SSN has on some of their results.
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THE MAGNETIC NATURE OF SUNSPOTS
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Created by large concentrations of magnetic flux which change the properties of convective heat transport
Rempel 2012
Cooler and darker than the surrounding area
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Image from Hinode
Typically appear in groups of mixed magnetic polarity
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Image from Hinode
Typically appear in groups of mixed magnetic polarity
• Sunspot groups have systematic tilt, which increases with latitude. • Their associated magnetic signature is typically called Active region.
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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They are believed to be a consequence of the buoyant emergence of twisted flux-tubes
See review by Fan (2009)
• Originating from toroidal bands of magnetic field located at the bottom of the convection zone.
• Tilted by the Coriolis force and helical convective turbulence.
• With starting magnetic field strengths of the order of 104-5 G. (Weber et al. 2011).
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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They are believed to be a consequence of the buoyant emergence of twisted flux-tubes
Image by A. van Ballegooijen
See review by Fan (2009)
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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SUNSPOTS, THE SOLAR CYCLE AND THE HELIOSPHERE
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Poloidal r - q
Toroidal f
Differential Rotation
Emergence and Decay of
Active Regions (Sunspots)
Crucial link in for the solar dynamo
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
Since we can only observe surface magnetism, sunspots are a window into the dynamo both in terms of the interior and the future.
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Highly energetic events are modulated by the solar cycle
Both Flares…
Aschwanden & Freeland 2012 Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Owens & Lockwood 2012
… and CMEs
Highly energetic events are modulated by the solar cycle
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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In terms of climate models the cycle also modulates two particularly
important quantities:
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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The radiative output of the Sun
• Particularly evident in UV and X-rays
Credit: SOHO/NASA/ESA
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Image taken from PMOD-WRC
• Can also be observed in total solar irradiance
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
The radiative output of the Sun
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Cosmic ray flux
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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The link to Climate and the Dynamo
• Solar irradiance represents the main source of energy input into the climate system. – UV variability greatly affects the upper
atmosphere.
• Cosmic rays have been proposed as seeds for the formation of clouds. – They can be used as a proxy for solar magnetism
that goes back farther than the 1600s
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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ESTIMATIONS OF TOTAL SOLAR IRRADIANCE AND THE SUNSPOT NUMBER
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
Credit: NASA/Goddard/SORCE
Cycle modulation of solar irradiance is a close fight between brightening (faculae)
and darkening (sunspots) features
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In order to calculate irradiance we need to estimate the fractions of the disk covered by sunspots and faculae and their contribution
qs qstI I sp spt I fc fct I
Quiet Sun Sunspots Faculae
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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• Based on the induction equation and limited to the surface of the Sun (not self excited).
• Driven by synthetic AR data in order to generate the weak fields associated with faculae consistently (SSN is used to generate it).
Surface Flux Transport Simulations Wang et al. 2005
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
Yeates & Mackay 2012
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• Number of ARs (or AR flux) for each cycle has been adjusted to sunspot number.
• Meridional flow is used as a free parameter to ensure agreement with open flux.
Surface Flux Transport Simulations Wang et al. 2005
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Surface Flux Transport Simulations Wang et al. 2005
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
• The working hypothesis is that the average unsigned magnetic field is a proxy for facular brightness.
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Surface Flux Transport Simulations Wang et al. 2005
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
• A linear relationship is found between cycle amplitude and cycle averaged TSI
• This suggest a linear sensitivity of these results to changes in the SSN
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• Simplified model for the evolution of different types of magnetic flux (F): (AR, open flux)
• AR fluxes and rate of emergence are taken from magnetic data (or from sunspot number).
• Open flux is taken from in-situ measurements
• The decay timescales are free parameters that obtained through an optimization process.
Models of the open flux Vieira et al. 2011 (MPS)
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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• Simplified model for the evolution of different types of magnetic flux (F): (AR, open flux)
Models of the open flux Vieira et al. 2011 (MPS)
AR
A
R
R
A AREt
F F
O
F
OF
O
F
t
F
F
R F
AR
A O
F
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
R F
AR
A O
F
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• Simplified model for the evolution of different types of magnetic flux (F): (AR, ephemeral, open flux)C
Models of the open flux Vieira et al. 2011 (MPS)
AR
A
R
R
A AREt
F F
O
F
OF
O
F
t
F
F
R F
AR
A O
F
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
R F
AR
A O
F
EPH
EP
EPH EP
H
HEt
F F
H F
EPH
EP O
F
H F
EPH
EP O
F
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Models of the open flux Vieira et al. 2011 (MPS)
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
• Simplified model for the evolution of different types of magnetic flux (F): (AR, ephemeral, open flux)
• Once you have an idea of the evolution of AR flux, you can use the Sunspot number to estimate which percentage of this flux belongs to spots and which to faculae.
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Differences introduced by using SSN vs. SSI have been studied directly
Krivova et al. J of A&STP (2011)
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
• Results suggest a proportional change of similar magnitude as the proposed corrections to the SSN
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MODULATION OF COSMIC RAYS (CR) AND THE USE OF THE SUNSPOT NUMBER TO INTERPRET COSMOGENIC PROXIES
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Solar wind drags magnetic field lines past the source surface generating a spiral
which gives structure to the heliosphere
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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The path of low energy CRs is affected by the solar wind and the
heliospheric magnetic field
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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CR modulation and solar activity
Cosmic rays
Earth FModulation
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
Isotopes
Open Magnetic
Flux
Solar Magnetic
field
Sunspot Number
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CR modulation and solar activity
Cosmic rays
Earth FModulation
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
Isotopes
Open Magnetic
Flux
Solar Magnetic
field
Sunspot Number
Known Energy
Spectrum
Atmospheric Model
Power Relationship
Open Flux Model
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CR modulation and solar activity
Cosmic rays
Earth FModulation
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
Isotopes
Open Magnetic
Flux
Solar Magnetic
field
Sunspot Number
Open Flux Model
Sunspot number input to
tune model
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As a first approximation of the impact of changes to the SSN on CR proxies
will be similar than to solar irradiance
Usoskin et al. 2003
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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As a first approximation of the impact of changes to the SSN on CR proxies
will be similar than to solar irradiance
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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As a first approximation of the impact of changes to the SSN on CR proxies
will be similar than to solar irradiance
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Solanki et al. 2004
As a first approximation of the impact of changes to the SSN on CR proxies
will be similar than to solar irradiance
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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IMPLICATIONS FOR DYNAMO, SOLAR CYCLE, AND CLIMATE STUDIES
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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• Theoretical models are not yet on a point where they can be used to make detailed and meaningful reconstruction of past solar activity.
• However, SSN and the CR proxies can and are used to make conclusions about dynamo operating regimes so is very important to have them right.
• Looking at solar irradiance and cosmic ray as the principal products of interest for the climate community I find data products to have variations of the same order as changes to the reference SSN
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013
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Acknowledgements
• Organizers for inviting me and help me come here.
• All participants for an amazingly fun, interesting and enlightening week.
Andrés Muñoz-Jaramillo – 3rd SSN Workshop, 22-25 January, 2013