The Effects of Solar Variability on Earth's Climate A Workshop Report (2012) / Chapter Skim
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Appendix C: Abstracts Prepared by Workshop Speakers
Appendix C: Abstracts Prepared by Workshop Speakers
Pages 38-50
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From page 38... ...
I will give an overview of solar irradiance measurements and recent progress to improve this record's accuracy. Using estimates of solar variability over long-term timescales relevant for climate studies, I will derive the record's accuracy and stability requirements and assess the current status for achieving these requirements, comparing to recent solar minima as examples.
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From page 39... ...
The GCR intensity is known to anti-correlate with the number of sunspots on the Sun -- having a higher intensity when there are few sunspots. This anticorrelation is the basis for using cosmogenic nuclei deposited in tree rings and ice cores as a proxy measure of solar activity dating back thousands of years.
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From page 40... ...
Such partial disappearance would agree better with radioisotope evidence that a weakened 11-year cycle persisted throughout the Maunder Minimum. Improved observations are under way to accurately measure the uncertain TSI contribution of the quiet Sun flux tubes down to sizes barely resolvable with the largest solar telescopes.3 Also, it remains to be seen whether 17th century photospheric magnetism weakened below the level observed during normal 11-year activity minima.4 During the extended activity minimum of 20082009, the main indices such as F10.7 and Mg II dipped several percent below their preceding 11-year minima.
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From page 41... ...
Improvement in geomagnetic field reconstructions, new knowledge about the intergalactic cosmic-ray spectrum, additional radionuclide records, and improved knowledge about the geochemical behavior of 14C and 10Be can reduce the 5 R Muscheler, F
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From page 42... ...
:189-219, 1998. SOURCE: Raimund Muscheler, Lund University, "The Record of Solar Forcing in Cosmogenic Isotope Data," presentation to the Committee on the Effects of Solar Variability on Earth's Climate, September 8, 2011.
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From page 43... ...
that is a simple consequence of CO2 radiative forcing estimates, and the classic experiments at the dawn of research on climate change with global climate models that showed very similar tropospheric responses to changes in the total solar irradiance and to changes in CO2. The importance of the frequency-dependence of climate responses in relating greenhouse gas, volcanic, and solar cycle responses will be mentioned.
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From page 44... ...
Climate Response to the Solar Cycle as Observed in the Stratosphere Lon L Hood, Lunar and Planetary Laboratory, University of Arizona Multiple linear regression analyses of satellite-derived stratospheric ozone and temperature records indicate the existence of significant responses to 11-year solar forcing primarily at tropical and subtropical latitudes.
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From page 45... ...
Specifically, we are investigating whether a statistically significant solar cycle response of the troposphere-ocean system exists that has characteristics consistent with producing the observed lower stratospheric response through a modification of planetary wave amplitudes. To characterize the troposphere-ocean response, a multiple linear regression statistical model is applied to Hadley Centre sea level pressure (SLP)
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From page 46... ...
These observations include, for peaks in the 11-year sunspot cycle, below-normal sea surface temperatures in the equatorial eastern Pacific, enhanced precipitation in the Pacific intertropical convergence zone and South Pacific convergence zone, and above-normal sea level pressure in the midlatitude North and South Pacific. To investigate what could be producing these signals in observations, two mechanisms, the top-down stratospheric response of ozone to fluctuations of shortwave solar forcing, and the bottom-up coupled ocean-atmosphere surface response, are included in versions of three global climate models with either mechanism acting alone or both together.
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From page 47... ...
Climate Response at Earth's Surface to Cyclic and Secular Solar Forcing Ka-Kit Tung, University of Washington I will review recent results on responses at the surface to the 11-year solar cycle and to the longer-term secular trend in the longest global temperature dataset. Finally I will discuss some new results on analyzing the 350-year Central England temperature record back to the Maunder Minimum, to see if there is a larger solar signature.
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From page 48... ...
HOx enhancements due to SPEs were confirmed by observations in the past solar cycle. A number of modeling studies have been undertaken over this time period that show predictions of enhanced HOx accompanied by decreased ozone due to energetic particles.
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From page 49... ...
family in the lower stratosphere by up to about 20 percent, with small associated ozone decreases of <2 percent. However, the variation in the GCR-driven change in NOy from solar maximum to solar minimum is less than about 5 percent, which results in annually averaged total ozone variations of <0.06 percent.
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From page 50... ...
flux as an indicator of chromospheric activity, or by photometric observations of solar cycles on decadal timescales. Early estimates of grand minimum frequency in solartype stars ranged from 10 to 30 percent.
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