Sentences with phrase «of irradiance variations»

This is in agreement with the recent results of [CITE], but it is in contrast to the earlier analysis of [CITE], and suggests that the source of the irradiance variations is the same for cycles 22 and 23, namely the evolution of the magnetic flux at the solar surface.

Data records of sufficient duration are expected to reveal the extent of irradiance variations over time that reflect a combination of cause and effect of climate change.

Not exact matches

11 Duration, in years, of a typical solar cycle, natural variations in the number of sunspots and flares that affect solar irradiance levels on Earth.

Solar irradiance modulation of Equator - to - Pole (Arctic) temperature gradients: Empirical evidence for climate variation on multi-decadal timescales

The «equilibrium» sensitivity of the global surface temperature to solar irradiance variations, which is calculated simply by dividing the absolute temperature on the earth's surface (288K) by the solar constant (1365Wm - 2), is based on the assumption that the climate response is linear in the whole temperature band starting at the zero point.

Dr. Benestad states: «From regression analysis cited by the authors (Douglass and Clader 2002, White et al. 1997), it seems possible that the sensitivity of global surface temperature to variations of total solar irradiance might be about 0.1 K / Wm -2.

On the other hand, Esper's data appear to be in close agreement with variations in cosmogenic isotopes whose production rates are indicators of variation in solar irradiance, and thus, global temperatures on Earth.

Typhoon variability was likely modulated further by the state of the East Asia summer monsoon (EASM) pattern, associated with variation in the magnitude of solar irradiance.

As examples of work in this category, I would mention Judith Lean's tireless efforts on relating luminosity to sunspot number, the work of Bard and colleagues on developing isotopic solar proxies like 10Be, Shindell's work on response to solar ultraviolet variability, and the work of Foukal et al on factors governing solar irradiance variations.

Important manifestations of such external forcing from space to the atmosphere are the variations in different solar parameters such as the solar irradiance (including solar UV) and solar particle fluxes, which can induce changes in the atmosphere both at local and global scales, and can influence over a large range of altitudes.

Let's set the stage by noting that, as a significant competitor to anthropogenic greenhouse forcing of recent climate change, the direct radiative forcing by solar irradiance variations is dead on arrival.

Changes in insolation are also thought to have arisen from small variations in solar irradiance, although both timing and magnitude of past solar radiation fluctuations are highly uncertain (see Chapters 2 and 6; Lean et al., 2002; Gray et al., 2005; Foukal et al., 2006).

Solar irradiance variations are sometimes assumed to be the most likely natural driver of climate change.

We only have direct observations of total solar irradiance (TSI) since the beginning of the satellite era and substantial evidence for variations in the level of solar activity (from cosmogenic isotopes or sunspot records) in the past.

Because of the variations of sunspots and faculae on the sun's surface, the total solar irradiance (TSI), also called the solar constant, varies on a roughly 11 - year cycle by about 0.07 %, which has been measured by orbiting satellites since 1978 [Lean, 1987, 1991; Wilson et al., 1981].

...» We describe the variations with time of the solar irradiance and of the flux of ejected magnetised plasma.

While the later is useful, as it is all that we have earlier than 1978 or so, direct measurements of irradiance show that the variation is at best 1 part in 1300 over the last forty or so years

In the May issue of Astronomy & Astrophysics, Shapiro et al. present a new long - term reconstruction of the solar irradiance that implies much greater variation over the last 7000 years than any previous ly reconstruction.

See e.g. this review paper (Schmidt et al, 2004), where the response of a climate model to estimated past changes in natural forcing due to solar irradiance variations and explosive volcanic eruptions, is shown to match the spatial pattern of reconstructed temperature changes during the «Little Ice Age» (which includes enhanced cooling in certain regions such as Europe).

They claim that the evidence for Milankovitch forcing of the ice ages implies that the planet is hypersensitive to solar irradiance variations.

The Top Of Atmosphere solar irradiance varies from about 1365.4 watts per meter squared to about 1366.4 watts / M ^ 2, but that variation (less than 1 %) doesn't modulate the global temperature significantly — see http://www.woodfortrees.org/plot/pmod/from:1978/mean:10/offset:-1366/plot/wti/from:1978/mean:10

Or, even more broadly, we know there's approx. 0,1 % variation of solar irradiance between two cycles minima (Willson 2003), how do we exclude with reasonable confidence the hypothesis that there is a 1 % variation between 21.000 y BP and 1750 AD?

The IPCC 2001 report states «Several recent reconstructions estimate that variations in solar irradiance give rise to a forcing at the Earth's surface of about 0.6 to 0.7 Wm - 2 since the Maunder Minimum and about half this over the 20th century... All reconstructions indicate that the direct effect of variations in solar forcing over the 20th century was about 20 to 25 % of the change in forcing due to increases in the well - mixed greenhouse gases.»

Title: «Shortwave forcing of the Earth's climate: Modern and historical variations in the Sun's irradiance and Earth's reflectance» Author, P.R. Goode, E. Pallé Journal: Journal of ATMOSPHERIC and SOLAR - TERRESTRIAL PHYSICS DoP: Sept 2007 DOI: 10.1016 / j.jastp.2007.06.011

The Holy Grail of climatology has always been to ascertain whether, and if so how, the sun might affect the Earth's energy budget to cause the climate swings observed throughout history despite the apparent inadequacy of the tiny variations in Total Solar Irradiance (TSI) that occur from one series of solar cycles to another.

Oceanic oscillations are sufficient to cancel out or enhance the effects of natural variations in solar irradiance or other forms of solar input to the heat budget of the Earth for variable periods of time.

Whatever wide - ranging coherence one finds at multi-decadal frequencies is more likely the result of global - scale variations in cloud - regulated thermalization of solar irradiance and the lagged advection of heat from the tropics by winds and ocean currents.

Douglas Hoyt and Kenneth Schatten, «A Discussion of Plausible Solar Irradiance Variations, 1700 - 1992,» Journal of Geophysical Research, v. 98, no.

A third example would be the research on how incoming solar irradiance influences China's thermometer temperature records, showing that over periods of many decades the variations in total solar irradiance in the upper atmosphere are matched by variations at the surface.

(See Soon & Legates 2013: Solar irradiance modulation of Equator - to - Pole (Arctic) temperature gradients: Empirical evidence for climate variation on multi-decadal timescales.)

Parsimony is not a grounds for ignoring the now mountain of evidence that solar activity does somehow drive climate much more powerfully than can be explained by the tiny variation in solar irradiance, and the implications of a solar explanation for 20th century warming are much different than for an internal - variation explanation.

«Since irradiance variations are apparently minimal, changes in the Earth's climate that seem to be associated with changes in the level of solar activity — the Maunder Minimum and the Little Ice age for example — would then seem to be due to terrestrial responses to more subtle changes in the Sun's spectrum of radiative output.

Soon, W. and D.R. Legates, 2013: Solar irradiance modulation of equator - to - pole (Arctic) temperature gradients: empirical evidence for climate variation on multi-decadal timescales, Journal of Atmospheric and Solar - Terrestrial Physics 93: 45 — 56.

Soon, W., 2005: Variable solar irradiance as a plausible agent for multidecadal variations in the Arctic - wide surface air temperature record of the past 130 years, Geophysical Research Letters32: doi.10.1029 / 2005GL023429.

Shortwave forcing of the Earth's climate: modern and historical variations in the Sun's irradiance and the Earth's reflectance, P.R. Goode, E. Palle, J. Atm.

We also show that a non-thermal solar component is necessarily present, indicating that the total solar contribution to the 20th century global warming, of ∆ Tsolar = 0.27 ± 0.07 ◦ C, is much larger than can be expected from variation in the total solar irradiance alone.

In the summary of Chapter 7, one can read that the effects of variation in solar radiation are negligible You seem to miss the whole point.: «The Chapter 7 authors are admitting strong evidence («many empirical relationships») for enhanced solar forcing (forcing beyond total solar irradiance, or TSI), even if they don't know what the mechanism is.»

There could also be other unknown mechanisms driven by solar changes that exaggerate the effect of small variations in total solar irradiance.

First, this is possible because helioseismic data provide the most precise measure ever of the solar cycle, which ultimately yields more profound physical limits on past irradiance variations.

Figure 1 (a) represents the corrected visible light from Neptune from 1950 to 2006; (b) shows the temperature anomalies of the Earth; (c) shows the total solar irradiance as a percent variation by year; (d) shows the ultraviolet emission from the Sun (Source: Hammel and Lockwood (2007)-RRB-.

Second, their temperature reconstructions were not based exclusively on TSI changes as the sole source of temperature variation, but included associated changes in spectral irradiance that would be expected to amplify TSI effects, changes in UV being one example.

Shortwave forcing of the earth's climate: Modern and historical variations in the sun's irradiance and the earth's reflectance.

In order to reliably interpret surface temperature variations we need a good idea of all the causal factors, including El Niño, solar irradiance, volcanic eruptions, observational biases, changes in ocean circulation and possible long term oscillations.

Regarding solar, most sceptics are focused on the solar variation between the 11 - year cycles and not on the irradiance variation between minima and maxima of the single cycles.

«All 18 periods of significant climate changes found during the last 7,500 years were entirely caused by corresponding quasi-bicentennial variations of [total solar irradiance] together with the subsequent feedback effects, which always control and totally determine cyclic mechanism of climatic changes from global warming to Little Ice Age.»

Solar forcing is the only known natural forcing acting to warm the climate over this period but it has increased much less than greenhouse gas forcing, and the observed pattern of long term tropospheric warming and stratospheric cooling is not consistent with the expected response to solar irradiance variations.

Although we focus on a hypothesized CR - cloud connection, we note that it is difficult to separate changes in the CR flux from accompanying variations in solar irradiance and the solar wind, for which numerous causal links to climate have also been proposed, including: the influence of UV spectral irradiance on stratospheric heating and dynamic stratosphere - troposphere links (Haigh 1996); UV irradiance and radiative damage to phytoplankton influencing the release of volatile precursor compounds which form sulphate aerosols over ocean environments (Kniveton et al. 2003); an amplification of total solar irradiance (TSI) variations by the addition of energy in cloud - free regions enhancing tropospheric circulation features (Meehl et al. 2008; Roy & Haigh 2010); numerous solar - related influences (including solar wind inputs) to the properties of the global electric circuit (GEC) and associated microphysical cloud changes (Tinsley 2008).

http://www.agci.org/docs/lean.pdf «Global (and regional) surface temperature fluctuations in the past 120 years reflect, as in the space era, a combination of solar, volcanic, ENSO, and anthropogenic influences, with relative contributions shown in Figure 6.22 The adopted solar brightness changes in this scenario are based on a solar surface flux transport model; although long - term changes are «50 % larger than the 11 - year irradiance cycle, they are significantly smaller than the original estimates based on variations in Sun - like stars and geomagnetic activity.

Just how effective this driver is has remained relatively uncertain, however, partly due to missing knowledge on the exact variation of the Sun's irradiance over time in different parts of the solar spectrum.

We find that most of the solar cycle variation in the total solar irradiance can be accounted for by the absolute magnetic field strength on the solar disk, if fields associated with dark and bright regions are considered separately.