scholarly journals A reconstruction of radiocarbon production and total solar irradiance from the Holocene <sup>14</sup>C and CO<sub>2</sub> records: implications of data and model uncertainties

2013 ◽  
Vol 9 (4) ◽  
pp. 1879-1909 ◽  
Author(s):  
R. Roth ◽  
F. Joos
Keyword(s):  
Solar Activity ◽  
Solar Irradiance ◽  
Surface Air Temperature ◽  
Total Solar Irradiance ◽  
Production Model ◽  
High Solar Activity ◽  
Solar Modulation ◽  
Time Lags ◽  
Instrumental Data ◽  
The Holocene

Abstract. Radiocarbon production, solar activity, total solar irradiance (TSI) and solar-induced climate change are reconstructed for the Holocene (10 to 0 kyr BP), and TSI is predicted for the next centuries. The IntCal09/SHCal04 radiocarbon and ice core CO2 records, reconstructions of the geomagnetic dipole, and instrumental data of solar activity are applied in the Bern3D-LPJ, a fully featured Earth system model of intermediate complexity including a 3-D dynamic ocean, ocean sediments, and a dynamic vegetation model, and in formulations linking radiocarbon production, the solar modulation potential, and TSI. Uncertainties are assessed using Monte Carlo simulations and bounding scenarios. Transient climate simulations span the past 21 thousand years, thereby considering the time lags and uncertainties associated with the last glacial termination. Our carbon-cycle-based modern estimate of radiocarbon production of 1.7 atoms cm−2 s−1 is lower than previously reported for the cosmogenic nuclide production model by Masarik and Beer (2009) and is more in-line with Kovaltsov et al. (2012). In contrast to earlier studies, periods of high solar activity were quite common not only in recent millennia, but throughout the Holocene. Notable deviations compared to earlier reconstructions are also found on decadal to centennial timescales. We show that earlier Holocene reconstructions, not accounting for the interhemispheric gradients in radiocarbon, are biased low. Solar activity is during 28% of the time higher than the modern average (650 MeV), but the absolute values remain weakly constrained due to uncertainties in the normalisation of the solar modulation to instrumental data. A recently published solar activity–TSI relationship yields small changes in Holocene TSI of the order of 1 W m−2 with a Maunder Minimum irradiance reduction of 0.85 ± 0.16 W m−2. Related solar-induced variations in global mean surface air temperature are simulated to be within 0.1 K. Autoregressive modelling suggests a declining trend of solar activity in the 21st century towards average Holocene conditions.

scholarly journals A reconstruction of radiocarbon production and total solar irradiance from the Holocene <sup>14</sup>C and CO<sub>2</sub> records: implications of data and model uncertainties

2013 ◽  
Vol 9 (2) ◽  
pp. 1165-1235 ◽  
Author(s):  
R. Roth ◽  
F. Joos
Keyword(s):  
Solar Activity ◽  
Carbon Cycle ◽  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
High Solar Activity ◽  
Solar Modulation ◽  
Total Production ◽  
Instrumental Data ◽  
The Holocene ◽  
The Past

Abstract. Past atmospheric CO2 concentrations reconstructed from polar ice cores combined with its Δ14C signature as conserved in tree-rings provide important information both on the cycling of carbon as well as the production of radiocarbon (Q) in the atmosphere. The latter is modulated by changes in the strength of the magnetic field enclosed in the solar wind and is a proxy for past changes in solar activity. We perform transient carbon-cycle simulations spanning the past 21 kyr using Bern3D-LPX, a fully featured Earth System Model of Intermediate Complexity (EMIC) with a 3-D ocean, sediment and a dynamic vegetation model. Using the latest atmospheric IntCal09/SHCal04 radiocarbon records, we reconstruct the Holocene radiocarbon fluxes and the total production rate. Our carbon-cycle based modern estimate of Q ≈ 1.7 atoms cm−2 s−1 is lower than previously reported by Masarik and Beer (2009) and more in line with Kovaltsov et al. (2012). Q is then translated into the solar modulation potential (Φ) using the latest geomagnetic field reconstruction and linked to a recent reanalysis of early instrumental data. In contrast to earlier reconstructions, our record suggests that periods of high solar activity (>600 MeV) were quite common not only in recent millennia but throughout the Holocene. Solar activity in our decadally-smoothed record is during 28% of the time higher than the modern average of 650 MeV during the past 9 ka. But due to considerable uncertainties in the normalization of Φ to instrumental data, the absolute value of Φ remains weakly constrained. Further, our simulations with a spatially resolved model (taking the interhemispheric Δ14C gradient into account) show that reconstructions that rely on the Northern Hemisphere 14C record only are biased towards low values during the Holocene. Notable deviations on decadal-to-centennial time scales are also found in comparison with earlier reconstructions. In a last step, past total solar irradiance (TSI) is quantified using a recently published Φ-TSI relationship yielding small changes in Holocene TSI of order 1 W m−2 with a Maunder Minimum irradiance reduction of 0.85 ± 0.17 W m−2. Future extension of TSI using autoregressive modeling suggest a declining solar activity in the next decades towards average Holocene conditions. Past TSI changes are finally translated into changes in surfaces atmospheric temperature (SAT) by forcing the Bern3D-LPX model with our new TSI record, yielding SAT anomalies of less than 0.1 K.

scholarly journals A 2600-year history of floods in the Bernese Alps, Switzerland: frequencies, mechanisms and climate forcing

2015 ◽  
Vol 19 (7) ◽  
pp. 3047-3072 ◽  
Author(s):  
L. Schulte ◽  
J. C. Peña ◽  
F. Carvalho ◽  
T. Schmidt ◽  
R. Julià ◽  
...  
Keyword(s):  
North Atlantic ◽  
Solar Irradiance ◽  
Catchment Area ◽  
Soil Formation ◽  
Organic Soil ◽  
Flood Damage ◽  
Total Solar Irradiance ◽  
Swiss Alps ◽  
Coarse Grained ◽  
Instrumental Data

Abstract. A 2600-year long composite palaeoflood record is reconstructed from high-resolution delta plain sediments of the Hasli–Aare floodplain on the northern slope of the Swiss Alps. Natural proxies compiled from sedimentary, geochemical and geomorphological data were calibrated by textual and factual sources and instrumental data. No fewer than 12 of the 14 historically recorded extreme events between 1480 and the termination of the Hasli–Aare river channel correction in 1875 were also identified by coarse-grained flood layers, log(Zr / Ti) peaks and factor 1 anomalies. Geomorphological, historical and instrumental data provide evidence for flood damage intensities and discharge estimations of severe and catastrophic historical floods. Spectral analysis of the geochemical and documentary flood series and several climate proxies (TSI, δ18O, tree-rings, NAO, SNAO) identify similar periodicities of around 60, 80, 100, 120 and 200 years during the last millennia, indicating the influence of the North Atlantic circulation and solar forcing on alpine flood dynamics. The composite floodplain record illustrates that periods of organic soil formation and deposition of phyllosilicates (from the medium high catchment area) match those of total solar irradiance maxima, suggesting reduced flood activity during warmer climate pulses. Aggradation with multiple sets of flood layers with increased contribution of siliciclasts from the highest catchment area (plutonic bedrock) (e.g. 1300–1350, 1420–1480, 1550–1620, 1650–1720 and 1811–1851 cal yr AD) occurred predominantly during periods with reduced solar irradiance, lower δ18O anomalies, cooler summer temperatures and phases of drier spring climate in the Alps. Increased water storage by glaciers, snow cover and snow patches susceptible to melting processes associated with rainfall episodes and abrupt rises in temperature substantially increased surface runoff on slopes and discharges of alpine rivers. This interpretation is in agreement with the findings that the severe and catastrophic historical floods in the Aare since 1670 occurred mostly during positive SNAO (Summer North Atlantic Oscillation) pulses after years or even decades dominated by negative SNAO and cooler annual temperatures.

scholarly journals The Total Solar Irradiance, UV Emission and Magnetic Flux during the Last Solar Cycle Minimum

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
E. E. Benevolenskaya ◽  
I. G. Kostuchenko
Keyword(s):  
Solar Activity ◽  
Magnetic Flux ◽  
Solar Irradiance ◽  
Solar Minimum ◽  
Total Solar Irradiance ◽  
Sunspot Activity ◽  
Ultraviolet Emission ◽  
Uv Emission ◽  
Surface Rotation ◽  
Spectral Solar Irradiance

We have analyzed the total solar irradiance (TSI) and the spectral solar irradiance as ultraviolet emission (UV) in the wavelength range 115–180 nm, observed with the instruments TIM and SOLSTICE within the framework of SORCE (the solar radiation and climate experiment) during the long solar minimum between the 23rd and 24th cycles. The wavelet analysis reveals an increase in the magnetic flux in the latitudinal zone of the sunspot activity, accompanied with an increase in the TSI and UV on the surface rotation timescales of solar activity complexes. In-phase coherent structures between the midlatitude magnetic flux and TSI/UV appear when the long-lived complexes of the solar activity are present. These complexes, which are related to long-lived sources of magnetic fields under the photosphere, are maintained by magnetic fluxes reappearing in the same longitudinal regions. During the deep solar minimum (the period of the absence of sunspots), a coherent structure has been found, in which the phase between the integrated midlatitude magnetic flux is ahead of the total solar irradiance on the timescales of the surface rotation.

scholarly journals Total solar irradiance during the Holocene

2009 ◽  
Vol 36 (19) ◽  
Author(s):  
F. Steinhilber ◽  
J. Beer ◽  
C. Fröhlich
Keyword(s):  
Solar Irradiance ◽  
Total Solar Irradiance ◽  
The Holocene

scholarly journals Long-term solar activity explored with wavelet methods

2006 ◽  
Vol 24 (2) ◽  
pp. 769-778 ◽  
Author(s):  
H. Lundstedt ◽  
L. Liszka ◽  
R. Lundin ◽  
R. Muscheler
Keyword(s):  
Solar Activity ◽  
Production Rate ◽  
Sunspot Number ◽  
Maunder Minimum ◽  
High Solar Activity ◽  
Solar Modulation ◽  
Group Sunspot ◽  
Group Sunspot Number ◽  
Wavelet Methods

Abstract. Long-term solar activity has been studied with a set of wavelet methods. The following indicators of long-term solar activity were used; the group sunspot number, the sunspot number, and the 14C production rate. Scalograms showed the very long-term scales of 2300 years (Hallstat cycle), 900-1000 years, 400-500 years, and 200 years (de Vries cycle). Scalograms of a newly-constructed 14C production rate showed interesting solar modulation during the Maunder minimum. Multi-Resolution Analysis (MRA) revealed the modulation in detail, as well as peaks of solar activity not seen in the sunspot number. In both the group sunspot number scalogram and the 14C production rate scalogram, a process appeared, starting or ending in late 1700. This process has not been discussed before. Its solar origin is unclear. The group sunspot number ampligram and the sunspot number ampligram showed the Maunder and the Dalton minima, and the period of high solar activity, which already started about 1900 and then decreased again after mid 1990. The decrease starts earlier for weaker components. Also, weak semiperiodic activity was found. Time Scale Spectra (TSS) showed both deterministic and stochastic processes behind the variability of the long-term solar activity. TSS of the 14C production rate, group sunspot number and Mt. Wilson sunspot index and plage index were compared in an attempt to interpret the features and processes behind the long-term variability.

scholarly journals Large-scale velocity fluctuations in polar solar wind

2005 ◽  
Vol 23 (3) ◽  
pp. 1025-1031 ◽  
Author(s):  
B. Bavassano ◽  
R. Bruno ◽  
R. D'Amicis
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
High Latitude ◽  
Large Scale ◽  
Activity Cycle ◽  
High Solar Activity ◽  
Time Lags ◽  
Polar Wind ◽  
Frequency Distributions ◽  
Long Range Correlations

Abstract. The 3-D structure of the solar wind varies dramatically along the Sun's activity cycle. In the present paper we focus on some properties of the polar solar wind. This is a fast, teneous, and steady flow (as compared to low-latitude conditions) that fills the high-latitude heliosphere at low solar activity. The polar wind has been extensively investigated by Ulysses, the first spacecraft to perform in-situ measurements in the high-latitude heliosphere. Though the polar wind is quite a uniform flow, fluctuations in its velocity do not appear negligible. A simple way to characterize the solar wind structure is that of performing a multi-scale statistical analysis of the wind velocity differences. The occurrence frequency distributions of velocity differences at time lags from 1 to 1024h and the corresponding values of mean, standard deviation, skewness, and kurtosis have been obtained. A comparison with previous results in ecliptic wind at both low and high solar activity has been performed. It comes out that the kind of trend observed in the distributions for changing scale is the same for the different solar wind regimes. Differences between different flows just have an effect on the values of the distribution moments and the scales at which the transition from non-Gaussian to Gaussian-like behaviours occurs. This is typical of systems in which random fluctuations are mixed to coherent structures of some characteristic size, in other words, systems where long-range correlations cannot be neglected.

scholarly journals Solar modulation of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales

2016 ◽  
Vol 12 (3) ◽  
pp. 799-805 ◽  
Author(s):  
Markus Czymzik ◽  
Raimund Muscheler ◽  
Achim Brauer
Keyword(s):  
Solar Activity ◽  
Atmospheric Circulation ◽  
Central Europe ◽  
Empirical Support ◽  
Total Solar Irradiance ◽  
Flood Frequency ◽  
Solar Modulation ◽  
Top Down ◽  
Discharge Data ◽  
Atmospheric Circulation Patterns

Abstract. Solar influences on climate variability are one of the most controversially discussed topics in climate research. We analyze solar forcing of flood frequency in central Europe during spring and summer on interannual to multi-centennial timescales, integrating daily discharge data of the River Ammer (southern Germany) back to AD 1926 (∼  solar cycles 16–23) and the 5500-year flood layer record from varved sediments of the downstream Ammersee. Flood frequency in the River Ammer discharge record is significantly correlated to changes in solar activity when the flood record lags the solar signal by 2–3 years (2-year lag: r = −0.375, p = 0.01; 3-year lag: r = −0.371, p = 0.03). Flood layer frequency in the Ammersee sediment record depicts distinct multi-decadal variations and significant correlations to a total solar irradiance reconstruction (r = −0.4, p <  0.0001) and 14C production rates (r = 0.37, p <  0.0001), reflecting changes in solar activity. On all timescales, flood frequency is higher when solar activity is reduced. In addition, the configuration of atmospheric circulation associated with periods of increased River Ammer flood frequency broadly resembles that during intervals of reduced solar activity, as expected to be induced by the so-called solar top-down mechanism by model studies. Both atmospheric patterns are characterized by an increase in meridional airflow associated with enhanced atmospheric blocking over central Europe. Therefore, the significant correlations as well as similar atmospheric circulation patterns might provide empirical support for a solar influence on hydroclimate extremes in central Europe during spring and summer by the so-called solar top-down mechanism.

scholarly journals Revised historical solar irradiance forcing

2018 ◽  
Vol 615 ◽  
pp. A85 ◽  
Author(s):  
T. Egorova ◽  
W. Schmutz ◽  
E. Rozanov ◽  
A. I. Shapiro ◽  
I. Usoskin ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Spectral Synthesis ◽  
Total Solar Irradiance ◽  
Magnetic Activity ◽  
Maunder Minimum ◽  
Solar Modulation ◽  
Solar Forcing ◽  
Quiet Sun ◽  
Solar Magnetic Activity ◽  
Spectral Solar Irradiance

Context. There is no consensus on the amplitude of historical solar forcing. The estimated magnitude of the total solar irradiance (TSI) difference between the Maunder minimum and the present time ranges from 0.1 to 6 W m−2 making the simulation of the past and future climate uncertain. One reason for this disagreement is the applied evolution of the quiet Sun brightness in solar irradiance reconstruction models. This work addresses the role of the quiet Sun model choice and updated solar magnetic activity proxies on the solar forcing reconstruction. Aims. We aim to establish a plausible range for the solar irradiance variability on decadal to millennial timescales. Methods. The spectral solar irradiance (SSI) is calculated as a weighted sum of the contributions from sunspot umbra, sunspot penumbra, faculae, and quiet Sun, which are pre-calculated with the NLTE Spectral SYnthesis code (NESSY). We introduce activity belts of the contributions from sunspots and faculae and a new structure model for the quietest state of the Sun. We assume that the brightness of the quiet Sun varies in time proportionally to the secular (22-yr smoothed) variation of the solar modulation potential. Results. A new reconstruction of the TSI and SSI covering the period 6000 BCE - 2015 CE is presented. The model simulates solar irradiance variability during the satellite era well. The TSI change between the Maunder and recent minima ranges between 3.7 and 4.5 W m−2 depending on the applied solar modulation potential. The implementation of a new quietest Sun model reduces, by approximately a factor of two, the relative solar forcing compared to the largest previous estimation, while the application of an updated solar modulation potential increases the forcing difference between the Maunder minimum and the present by 25–40%.

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