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Solar activity over the last 1150 years: Does it correlate with climate?
Abstract
Previous studies of solar influence on climate variations have suffered from the relatively short length of continuous solar observations of less than 400 years. Here we present a reconstructed series of sunspot numbers to study this question over a considerably longer time interval of 1150 years. Comparison of these solar data sets with the Earth's hemispheric and global mean surface temperature series reveals very similar trends. In particular, the solar series also show a 'hockey-stick' shape. The long-term trends in solar data and in northern hemisphere temperatures have a correlation coefficient of about 0.7 - 0.8 at a 94% - 98% confidence level. The full data series correlate at a similar significance level, with the bulk of the correlation being due to the similarity in trends. The last 30 years are not considered, however. In this time the climate and solar data diverge strongly from each other.
... The impact of solar activity and cosmic radiation on the global climate is indisputable ( Hoyt Over the past few centuries of observation, the number of sunspots has increased while the Earth has been warming. It can be concluded that solar activity affects the global climate, causing warming of the planet ( Usoskin et al. 2005). This view is shared by Boryczka et al. (2012), who, based on the synchronicity of multiyear changes in air temperature in Warsaw and Wolf numbers, demonstrated that the Sun's activity is one of the principal causes of climate change. ...
... However, in recent decades, air temperature has increased considerably, whereas solar activity has shown only small changes and, moreover, a downward trend ( Lockwood 2008). Because total solar radiation, ultraviolet radiation, and cosmic ray flux have not shown any significant changing trend in the past thirty years, researchers have concluded that at least the last episode of warming must have a different cause ( Usoskin et al. 2005). On the other hand, Scafetta and West (2006) postulate that global warming has been progressing at a much faster rate since 1975 than could be expected if the Sun were the sole cause. ...
This article discusses air temperature variability at Mount Śnieżka in the Sudetes from 1881 to 2012. It analyzes the relationship between changing trends in mean annual air temperature (Tavg) and solar activity, expressed by the mean annual Wolf number. The characteristic feature of changes in annual mean extremes (Tmax, Tmin) and Tavg at Mount Śnieżka is an upward trend. The increase of Tmin (0.148 °C/10 years) has been twice as fast as that for Tmax (0.069 °C/10 years). A strong correlation (almost 1.0) was found between the mean annual Wolf number for twenty-two-year cycles of magnetic changes in the Sun and 1988. During the 1989–2012 cycle, there was a strong increase in Tavg and, at the same time, a decrease in the mean annual Wolf number.
... Wanner et al. (2000) are dating the onset of Introduction Glaser, 2008). Following the sunspot numbers after Usoskin et al. (2004), the first flood-rich period exactly 5 coincides with a period of sunspot minima. According to Fig. 4, the t test value shows significant changes with the beginning and the end of Period #1. ...
... According to the first definition of the Spoerer Minimum, another sunspot minimum coincides with a floodrich period (here period #3). According to the sunspot data of Usoskin et al. (2004), the flood frequency maximum of period #3 also corresponds to the low sunspot numbers of the Spoerer Minimum. ...
This paper describes the flood sensitivity of the Bavarian part of the Alpine Foreland of Germany and addresses different questions concerning climate variability and flood frequencies, from the 14th century until today. The focal point of the paper is the flood frequency of the superordinate spatial unit of the Bavarian Foreland. Based on written historical sources, the flood history of the Alpine Foreland of Germany can be reconstructed back to the 14th century. One major result is the occurrence of "flood-rich" and "flood-poor" episodes in almost cyclical sequences. Flood-rich periods, before the 16th century based on limited available data, were recorded in the periods 1300–1335, 1370–1450, 1470–1525, 1555–1590, 1615–1665, 1730–1780, 1820–1870, and 1910–1955 as well as in a ninth period beginning in 1980. The flood-rich periods are characterized by longer flood duration. Most of the flood-rich and flood-poor periods (in particular the beginning and the end of them) can be connected to changes in natural climate variability. These include changing sunspot numbers (as a measure of solar activity), so-called Little Ice Age type events (LIATEs) as well as changes in the North Atlantic Oscillation (NAO). Climate signals from external forcing factors, which could be used to explain the changing flood frequencies in the Bavarian Alpine Foreland, end in 1930. Relationships within the climate system such as the correlation of flood frequencies with the NAO have changed during the transition from the post Little Ice Age period to the Modern Climate Optimum around 1930. Natural climate variability might have been overlaid by anthropogenic climate change.
... Coughlin and Tung (2004) found an 11-year sun-correlated signal in the lower troposphere. Usoskin et al. (2004bUsoskin et al. ( , 2004c studied the correlation between solar activity and surface temperature over the last 1150 years and found a correlation coefficient of 0.7-0.8 with a significance level ranging between 94% and 98%. De Jager and Usoskin (2006) Fig. 3) shows significant correlation, the correlation coefficient being 0.77 ( + 0.10/ À0.17) with a significance level of 99.8%. ...
... To extend the record of solar activity indirect proxy data can be derived from measurements of the cosmogenic radionuclides 10 Be and 14 C (radiocarbon) in natural archives such as ice cores and tree rings (Beer et al., 1990(Beer et al., , 2006Muscheler et al., 2004;Stuiver et al., 1991;Solanki et al., 2004;Usoskin et al., 2004bUsoskin et al., , 2004cvan Geel, 2008, Steinhilber et al., 2009). Cosmogenic radionuclides are produced continuously in the atmosphere as a result of the interaction of galactic cosmic rays with nitrogen and oxygen. ...
This investigation is a follow-up of a paper in which we showed that both major magnetic components of the solar dynamo, viz. the toroidal and the poloidal ones, are correlated with average terrestrial surface temperatures. Here, we quantify, improve and specify that result and search for their causes.We studied seven recent temperature files. They were smoothed in order to eliminate the Schwabe-type (11 years) variations. While the total temperature gradient over the period of investigation (1610–1970) is 0.087 °C/century; a gradient of 0.077 °C/century is correlated with the equatorial (toroidal) magnetic field component. Half of it is explained by the increase of the Total Solar Irradiance over the period of investigation, while the other half is due to feedback by evaporated water vapour. A yet unexplained gradient of −0.040 °C/century is correlated with the polar (poloidal) magnetic field. The residual temperature increase over that period, not correlated with solar variability, is 0.051 °C/century. It is ascribed to climatologic forcings and internal modes of variation.We used these results to study present terrestrial surface warming. By subtracting the above-mentioned components from the observed temperatures we found a residual excess of 0.31° in 1999, this being the triangularly weighted residual over the period 1990–2008.We show that solar forcing of the ground temperature associated with significant feedback is a regularly occurring feature, by describing some well observed events during the Holocene.
... Spätestens mit der Auswirkung von FCKW (Fluorchlorkohlenwasserstoffe) auf die Ozonschicht wurde jedoch das Gegenteil bewiesen. Auch Argumente, wie eine wesentlich stärkere Beteiligung an den CO2-Emissionen durch Vulkane ( Hards, 2005;Mörner und Etiope, 2002) oder ein Anstieg der globalen Erwärmung durch eine erhöhte Sonnenaktivität ( Usoskin et al., 2005), konnten widerlegt werden, da keine Zunahme der vulkanischen Aktivität im entsprechenden Zeitraum festgestellt werden kann und die solare Aktivität sogar eine entsprechende Entwicklung leicht kompensieren konnte (klimafakten. de, 2014 20% zum anthropogenen Treibhauseffekt bei. ...
zur Erlangung des Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.) genehmigte D i s s e r t a t i o n von Kevin Schaper aus Hildesheim Dieses Werk ist copyrightgeschützt und darf in keiner Form vervielfältigt werden noch an Dritte weitergegeben werden. Es gilt nur für den persönlichen Gebrauch.
... While there are studies (see for example, Rind, 1998, 2009;West, 2003, 2005;Scafetta et al., 2004;Scafetta, 2009Scafetta, , 2011Folland et al., 2013;Zhou and Tung, 2013) that find significant relationships between solar radiation and global temperatures, one hand. On the other hand, there are some authors who claim that the two variables are unrelated (see for example, Pittock, 1978Pittock, , 1983Pittock, , 2009Love et al., 2011;Usoskin, et al., 2004). Thus, there is no clear-cut consensus about the possibility of a relationship between solar irradiance and global temperatures (Gil-Alana et al., 2014). ...
In a recent paper, Gupta et al., (2015), analyzed whether sunspot numbers cause global temperatures based on monthly data covering the period 1880:1-2013:9. The authors find that standard time domain Granger causality test fails to reject the null hypothesis that sunspot numbers does not cause global temperatures for both full and sub-samples, namely 1880:1-1936:2, 1936:3-1986:11 and 1986:12-2013:9 (identified based on tests of structural breaks). However, frequency domain causality test detects predictability for the full-sample at short (2–2.6 months) cycle lengths, but not the sub-samples. But since, full-sample causality cannot be relied upon due to structural breaks, Gupta et al., (2015) concludes that the evidence of causality running from sunspot numbers to global temperatures is weak and inconclusive. Given the importance of the issue of global warming, our current paper aims to revisit this issue of whether sunspot numbers cause global temperatures, using the same data set and sub-samples used by Gupta et al., (2015), based on an nonparametric Singular Spectrum Analysis (SSA)-based causality test. Based on this test, we however, show that sunspot numbers have predictive ability for global temperatures for the three sub-samples, over and above the full-sample. Thus, generally speaking, our non-parametric SSA-based causality test outperformed both time domain and frequency domain causality tests and highlighted that sunspot numbers have always been important in predicting global temperatures.
... This includes authors such as Pittock (1978Pittock ( , 1983Pittock ( , 2009), Love et al. (2011) and others. Usoskin et al. (2005), using a long span of data of about 1150 years, showed that solar activity might be highly correlated with climate. Nevertheless, these authors claim that sunspot numbers cannot explain the warming effect in the temperatures in the last 30 years, whereas they find significant correlation between sunspot number and geomagnetic activity. ...
This article applies the causality test in the frequency domain, developed
by Breitung and Candelon (2006), to analyse whether sunspot numbers
(used as a partial approximation to solar irradiance) cause global temperatures,
using monthly data covering the time period 1880:1–2013:9.
While standard time domain Granger causality test fails to reject the null
hypothesis that sunspot numbers do not cause global temperatures for
both full and sub-samples (identified based on tests of structural breaks),
the frequency domain causality test detects predictability for both the
full-sample and the last sub-sample at short (2–2.6 months) and long
(10.3 months and above) cycle lengths, respectively. Our results highlight
the importance of analysing causality using the frequency domain
test, which, unlike the time domain Granger causality test, allows us to
decompose causality by different time horizons, and hence, could detect
predictability at certain cycle lengths even when the time domain causality
test might fail to pick up any causality. Further, given the widespread
discussion in the literature, those results for the full-sample
causality, irrespective of whether it is in time or frequency domains,
cannot be relied upon when there are structural breaks present, and one
needs to draw inference regarding causality from the sub-samples, we
can conclude that there has been an emergence of causality running from
sunspot numbers to global temperatures only recently at cycle length of
10.3 months and above.
... Longer/ bigger rivers mediate and smooth the influence of the factors that alter the climate signals, factors such as local rainfalls, evaporation, topography, lithology, soils, and vegetation (Labat 2008). Usoskin et al. (2005) have shown that sunspot influence on air temperature in the Northern Hemisphere has a 10-year lag, the solar maxima preceding the air temperature increase. Moreover, Huth et al. (2009) have shown that solar activity affects all oscillations in the Northern Hemisphere. ...
The influence of some climatic oscillations and sunspot number on river flows in Romania, Ukraine, and Moldova is verified by using standard wavelet analyses. The selected climate oscillations are Arctic Oscillation (AO), Antarctic Oscillation (AAO), East Atlantic Oscillation (EAO), East Atlantic/West Russia Oscillation (EAWRO), NINO3.4, North Atlantic Oscillation (NAO), Pacific/North America Oscillation (PNAO), Pacific Decadal Oscillation (PDO), Polar/Eurasia Oscillation (PEO), Scandinavian Oscillation (ScandO), Southern Oscillation (SO), and West Pacific Oscillation (WPO). Forty-five hydrological stations from an area of 45,000 km(2) were used in order to discover the spatial evolution of the periodicities found in rivers. The wavelet analysis is novel for the rivers in the study area. There is an important difference between the periodicities found in mountain and plateau areas and those found in the plain area. There is a general downstream increase in the confidence level of the identified periods, even if the atmospheric precipitation has more relevant periodicities in the mountain area. The periodicities can be grouped into two compact groups: 1-16.5 and 27.8-55.6 years. The correlation matrix of the global wavelet spectrum (GWS) values indicates that NAO, EAWRO, PDO, and the sunspot number are the main factors that generate the periodicities in rivers. It is the first time when the influence of PDO on local rivers is proven. All river periodicities smaller than 16 years have a confidence level of 0.95 or above, as proven by the GWS analysis of the daily discharge data, and are caused by multiple external factors.
... Pittock [14,15] is of the opinion that those authors that obtained significant relationships between sunspot numbers and temperatures such as Scafetta and West [18], Scafetta et al. [19] and West and Grigolini [20] might have produced errors due to data handling and other statistical problems, though similar arguments are claimed by those authors arguing just the contrary. Usoskin et al. [21], using a long span of data of about 1150 years showed that solar activity might be highly correlated with climate. Nevertheless, these authors claim that sunspot numbers cannot explain the warming effect in the temperatures in the last 30 years, whereas they find a significant correlation between sunspot number and geomagnetic activity. ...
This paper argues that the methods used by the establishment climate science community are not fit for purpose and that a new forecasting paradigm should be adopted. Earth’s climate is the result of resonances and beats between various quasi-cyclic processes of varying wavelengths. It is not possible to forecast the future, unless we have a good understanding of where the earth is in time in relation to the current phases of those different interacting natural quasi periodicities. Evidence is presented specifying the timing and amplitude of the natural 60 ± year and, more importantly, 1000 year periodicities (observed emergent behaviors) that are so obvious in the temperature record. Data related to the solar climate driver are discussed and the solar cycle 22 low in the neutron count (high solar activity) in 1991 is identified as a solar activity millennial peak and correlated with the millennial peak – inversion point – in the RSS temperature trend in about 2004. The cyclic trends are projected forward and predict a probable general temperature decline in the coming decades and centuries. Estimates of the timing and amplitude of the coming cooling are made. If the real climate outcomes follow a trend which approaches the near term forecasts of this working hypothesis, the divergence between the IPCC forecasts and those projected by this paper will be so large by 2021 as to make the current, supposedly actionable, level of confidence in the IPCC forecasts untenable.
Virtually all climate misinformation can be divided into five categories: fake experts, cherry picking, logical fallacies, impossible expectations and conspiracy theories. The most common climate myths are grouped into these five categories, examining the rhetorical techniques employed to mislead and explaining the science that puts the myths in proper context.
This paper describes the flood sensitivity of the Bavarian part of the Alpine Foreland of DEU and addresses different questions concerning climate variability and flood frequencies, from the 14th century until today. The focal point of the paper is the flood frequency of the superordinate spatial unit of the Bavarian Foreland. Based on written historical sources, the flood history of the Alpine Foreland of DEU can be reconstructed back to the 14th century. One major result is the occurrence of "flood-rich" and "flood-poor" episodes in almost cyclical sequences. Flood-rich periods, before the 16th century based on limited available data, were recorded in the periods 1300-1335, 1370-1450, 1470-1525, 1555-1590, 1615-1665, 1730-1780, 1820-1870, and 1910-1955 as well as in a ninth period beginning in 1980. The flood-rich periods are characterized by longer flood duration. Most of the flood-rich and flood-poor periods (in particular the beginning and the end of them) can be connected to changes in natural climate variability. These include changing sunspot numbers (as a measure of solar activity), so-called Little Ice Age type events (LIATEs) as well as changes in the North Atlantic Oscillation (NAO). Climate signals from external forcing factors, which could be used to explain the changing flood frequencies in the Bavarian Alpine Foreland, end in 1930. Relationships within the climate system such as the correlation of flood frequencies with the NAO have changed during the transition from the post Little Ice Age period to the Modern Climate Optimum around 1930. Natural climate variability might have been overlaid by anthropogenic climate change.
The results of meteorological measurements carried out continuously on Mt Śnieżka in Karkonosze
mountains since 1880 well document the warming observed on a global scale. Data analysis indicates warming
expressed by an increase in the mean annual air temperaturę of 0.8 °C/100 years. A much higher temperature increase was recorded in the last two decades at the turn of the twenty-first century. Mean decade air temperatures increased from −0.1 to 1.5 °C. It has been shown that there are relationships between air temperature at Mt Śnieżka and global mechanisms of atmospheric and oceanic circulation. Thermal conditions of the Karkonosze (Mt Śnieżka) accurately reflect global climate trends and impact of the North Atlantic Oscillation (NAO) index, macrotypes of atmospheric circulation in Europe (GWL) and Atlantic Multidecadal Oscillation (AMO). The increase in air temperature during the 1989–2012 solar magnetic cycle may reveal a synergy effect to which astrophysical effects and atmospheric and oceanic circulation effects contribute, modified by constantly increasing anthropogenic factors.
[1] We present reconstructions of Northern and Southern Hemisphere mean surface temperature over the past two millennia based on high-resolution ‘proxy’ temperature data which retain millennial-scale variability. These reconstructions indicate that late 20th century warmth is unprecedented for at least roughly the past two millennia for the Northern Hemisphere. Conclusions for the Southern Hemisphere and global mean temperature are limited by the sparseness of available proxy data in the Southern Hemisphere at present.
To estimate the effect of the solar variability on the climate, two estimates of the solar intensity variations during the last three centuries have been used as forcing in numerical simulations. The model employed to carry out the experiments was the same coupled global ocean-atmosphere model used in a number of studies to assess the effect of the anthropogenic greenhouse gases on climate. The near surface temperature and the tropospheric temperature distribution shows a clear response to the variability of the solar input. Even the thermohaline circulation reacts on the large amplitudes in the forcing. In the stratosphere, the response pattern is similar as in the observations, however, the 11-year cycle found in the forcing data does not excite an appreciable response. This might be due to the missing parameterisation of the increase in the UV-radiation at the solar cycle maximum and the connected increase of the stratospheric ozone concentration.
Since November 1978 a complete set of total solar irradiance (TSI) measurements from space is available, yielding a time series of 21 years. From measurements made by different space radiometers (HF on NIMBUS-7, ACRIMI on SMM, ACRIMII on UARS and VIRGO on SOHO) a composite record of TSI can be compiled. The corrections which are needed for each radiometer, mainly to compensate for degradation, but also for operational influences are described. ACRIMI (1980–1989) and ACRIMII (1992–1995) are taken as reference because their degradation was monitored by inflight comparisons with spare radiometers; since 1996 VIRGO is used as reference. The scale of ACRIM II is adjusted to ACRIM I by comparison with NIMBUS-7 and ERBE. The reliability of this adjustment depends strongly on the stability of the HF and ERBE radiometer during the period of the gap between the ACRIMs which is discussed in detail together with an assessment of the overall precision of the composite.
The response of the lower and middle atmosphere to variations in solar irradiance typical of those observed to take place over the 11-year activity cycle has been investigated. The effects on radiative heating rates of changing total solar irradiance, solar spectral irradiance and two different assumptions concerning stratospheric ozone have been studied with a radiative transfer code. The response in the stratosphere depends on the changes specified in the ozone distribution which is not well known. A general circulation model (GCM) of the atmosphere up to 0.1mbar (about 65km) has been used to study the impacts of these changes on the thermodynamical structure. The results in the troposphere are very similar to those reported by Haigh99 using a quite different GCM. In the middle atmosphere the model is able to reproduce quite well the observed seasonal evolution of temperature and wind anomalies. Calculations of radiative forcing due to solar variation are presented. These show that the thermal infrared component of the forcing, due to warming of the stratosphere, is important but suggest a near balance between the longwave and shortwave effects of the increased ozone so that ozone change may not be important for net radiative forcing. However, the structure of the ozone change does affect the detailed temperature response and the spectral composition of the radiation entering the troposphere.
Building on recent studies, we attempt hemispheric temperature reconstructions with proxy data networks for the past millennium. We focus not just on the reconstructions, but the uncertainties therein, and important caveats. Though expanded uncertainties prevent decisive conclusions for the period prior to AD 1400, our results suggest that the latter 20th century is anomalous in the context of at least the past millennium. The 1990s was the warmest decade, and 1998 the warmest year, at moderately high levels of confidence. The 20th century warming counters a millennial-scale cooling trend which is consistent with long-term astronomical forcing.
Contents: Solar global changes. Total and spectral irradiance variability. Modelling total and spectral irradiance. Climate effects of solar variability. Comparison of CME activity: solar cycle maximum and minimum. Initiation of CMEs. CMEs, ICMEs and space weather. Interplanetary shock waves and solar energetic particles. Future activities. JOSO Meeting. Miscellaneous topics. ISCS working groups. Late papers.
The change in the irradiance spectrum of the Sun from 1700 to the last solar minimum is determined and compared to the change in the spectrum between ac-tivity minimum and maximum. For this purpose we have used detailed model flux spectra of solar magnetic features. Also, time-series of the solar spectral irradiance since 1700 in different wavelength bands are reconstructed. We expect that these reconstructions are more accurate than previously published ones, although they suffer (like all reconstructions of solar irradiance on such time-scales) from uncertainties in our knowledge of the evolution of the solar network with time.
A correlation between a global average of low cloud cover and the flux of cosmic rays incident in the atmosphere has been observed during the last solar cycle. The ionising potential of Earth bound cosmic rays are modulated by the state of the heliosphere, while clouds play an important role in the Earth''s radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth''s climate. Recent satellite observations have further revealed a correlation between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (>273K) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (1%) a liquid cloud drop will only form in the presence of an aerosol, which acts as a condensation site. The droplet distribution of a cloud will then depend on the number of aerosols activated as cloud condensation nuclei (CCN) and the level of super saturation. Based on observational evidence it is argued that a mechanism to explain the cosmic ray-cloud link might be found through the role of atmospheric ionisation in aerosol production and/or growth. Observations of local aerosol increases in low cloud due to ship exhaust indicate that a small perturbation in atmospheric aerosol can have a major impact on low cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth''s radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability in cosmic ray intensities. Such changes are in agreement with the sign of cloud radiative forcing associated with cosmic ray variability as estimated from satellite observations.
Continuous direct records of solar variability are limited to the telescopic era covering approximately the past four centuries. For longer records one has to rely on indirect indices such as cosmogenic radionuclides. Their production rate is modulated by magnetic properties of the solar wind. Using a parameterisation of the solar activity and a Monte Carlo simulation model describing the interaction of the cosmic rays with the atmosphere, the production rate for each cosmogenic nuclide of interest can be calculated as a function of solar activity. Analysis of appropriate well-dated natural archives such as ice cores or tree rings offers the possibility to reconstruct the solar activity over many millennia. However, the interpretation of the cosmogenic nuclide records from these archives is difficult. The measured concentrations contain not only information on solar activity but also on changes in the geomagnetic field intensity and the transport from the atmosphere into the archive where, under ideal conditions, no further processes take place. Comparison of different nuclides (e.g. 10Be and 14C) that are produced in a very similar way but exhibit a completely different geochemical behaviour, allows us to separate production effects from system effects.
The presently available data show cyclic variability ranging from 11-year to millennial time scale periodicities with changing amplitudes, as well as irregularly distributed intervals of very low solar activity (so called minima, e.g. Maunder minimum) lasting typically 100 years.
Cosmic rays are the main source of ionization in the atmosphere at altitudes below 55–60km. This circumstance, together with the fact that cosmic ray flux modulation closely mirrors the solar activity time history, makes cosmic rays a good candidate as a possible mediator in the solar variability – climate relationship. The observed cosmic ray flux variations are described with the aim of emphasizing the features which may be useful in the search of correlation between cosmic rays and atmospheric phenomena.
The NCEP/NCAR re-analyses of the global data as high as 10hPa have made it possible to examine the influence of the 11-year sunspot cycle on the lower stratosphere over the entire globe. Previously, the signal of the solar cycle had been detected in the temperatures and heights of the stratosphere at 30hPa and below on the Northern Hemisphere by means of a data set from the Freie Universität Berlin. The global re-analyses show that the signal exists on the Southern Hemisphere too, and that it is almost a mirror image of that on the Northern Hemisphere. The largest temperature correlations with the solar cycle move from one summer hemisphere to the other, and the largest height correlations move poleward within each hemisphere from winter to summer.
The correlations are weakest over the whole globe in the northern winter. If, however, one divides the data into the winters when the equatorial Quasi-Biennial Oscillation was easterly or westerly, the arctic correlations become positive and large in the west years, but insignificantly small over the rest of the earth. The correlations in the east years are negative in the Arctic but positive in the subtropics and tropics on both hemispheres.
The difference between the east and west years in January-February can be ascribed to the fact that the dominant stratospheric teleconnection and the solar influence work in the same direction in the east years but oppose each other in the west years.
Solar radiation at wavelengths below 300 nm is almost completely absorbed by the Earth’s atmosphere, becoming the dominant direct energy source and playing a major role in the chemistry and dynamics. Even small changes in this incoming radiation field will have both direct and indirect influences on atmospheric processes, and perhaps will affect the Earth’s climate as well. Some of the very earliest space missions included devices to measure solar ultraviolet irradiance, but for the most part they lacked the necessary precision and accuracy to record true solar variability over long time periods. The technology has continued to improve, and today reliable measurements over time scales up to, and including, the 11-year solar cycle, are being obtained. This review provides a summary of measurements made during the most recent solar cycle (number 22 extending from 1986 1996), with emphasis on the spectral range 120-300 nm. Comparisons and validations of recent data sets are considered, together with an assessment of the present understanding of the solar variations. There is now general agreement that for solar cycle 22 the variation is as large as a factor of two at the shortest wavelengths, decreasing to roughly 10% near 200 nm. Proceeding to wavelengths above 200 nm the solar variability continues to decrease, and at about 300 nm it becomes smaller than the present measurement capability of about 1%.
We present an extension of the model of \citet{Solanki:etal:2000} that allows us to reconstruct the time evolution of both the total and the open magnetic flux at the solar surface since 1700. The flux emerging in large active regions is determined using the sunspot number as a proxy, while the flux emergence in small ephemeral regions is described by an extended cycle whose amplitude and length are related to the corresponding sunspot cycle. Both types of regions contribute to the open flux, which is the source of the heliospheric field. The overlap of the activity cycles of ephemeral regions leads to a secular variation of the total cycle-related magnetic flux (active region flux + ephemeral region flux + open flux). The model results indicate that the total surface flux has doubled in the first half of the last century. The evolution of the open flux is in good agreement with the reconstruction by \citet{Lockwood:etal:1999}.
The most striking feature of the Sun's magnetic field is its cyclic behaviour. The number of sunspots, which are dark regions of strong magnetic field on the Sun's surface, varies with a period of about 11 years. Superposed on this cycle are secular changes that occur on timescales of centuries and events like the Maunder minimum in the second half of the seventeenth century, when there were very few sunspots. A part of the Sun's magnetic field reaches out from the surface into interplanetary space, and it was recently discovered that the average strength of this interplanetary field has doubled in the past 100 years. There has hitherto been no clear explanation for this doubling. Here we present a model describing the long-term evolution of the Sun's large-scale magnetic field, which reproduces the doubling of the interplanetary field. The model indicates that there is a direct connection between the length of the sunspot cycle and the secular variations.
The extension of the sunspot number series backward in time is of considerable interest for dynamo theory, solar, stellar, and climate research. We have used records of the (10)Be concentration in polar ice to reconstruct the average sunspot activity level for the period between the year 850 to the present. Our method uses physical models for processes connecting the (10)Be concentration with the sunspot number. The reconstruction shows reliably that the period of high solar activity during the last 60 years is unique throughout the past 1150 years. This nearly triples the time interval for which such a statement could be made previously.
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Solar Variability as an Input to the Earth's Environment
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