Sentences with phrase «irradiance variations»

Krivova, N. A., Solanki, S. K., Fligge, A. & Unruh, Y. C. Reconstruction of solar irradiance variations in cycle 23: is solar surface magnetism the cause?

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.

It misses the point when it comes to the earth's climate's non-linear response to solar irradiance variation for example, though.

Tying those factors together in order to estimate solar irradiance variations in the past is crucial for attributing past climate changes, particularly in the pre-industrial.

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.

«Solar Total Irradiance Variations and the Global Sea Surface Temperature Record.»

There is nothing in climate physics to suggest that the sensitivity of climate to solar irradiance variation differs substantially from the sensitivity to infrared radiative forcing arising from greenhouse gas changes.

«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.

For the period after 1974, the model makes use of the full - disc magnetograms of the Sun and reproduces up to 97 % of the measured irradiance variation.

The effect of solar UV irradiance variations on the Earth's atmosphere.

We also demonstrate that SPM data can be employed to reconstruct total solar irradiance variations with almost the same accuracy as recently shown for MDI data.

Here (Krivova and Solanki) say their ``... models of solar irradiance variation... progress over the last half decade....

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.

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.

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.

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

See e.g. our 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) as well as the smaller hemispheric - mean changes.

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

They noted that empirical models based upon sunspots and faculae do not account for all irradiance variations observed over an activity cycle (see also NRC (1994)-RRB- and base their con - elation on an observed relationship between brightness and excess chromospheric emission, using the Ca II H and...»

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

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.

The model assumes that solar irradiance variations are caused by surface magnetism and its single free parameter is kept at the same value for both cycles.

The amplitude of the solar irradiance variation is smaller than the planetary energy

This suggests that the same driver of the irradiance variations, namely the evolution of the magnetic flux at the solar surface, is acting in cycles 21 — 23.

Thus, the basic magnitude of the solar irradiance variations is given by the difference between the irradiance of the present quiet Sun (composed from a distribution of brightness components defined in Appendix A) and the irradiance from component A (see Eq.

A model of solar irradiance variations is presented which is based on the assumption that solar surface magnetism is responsible for all total irradiance changes on time scales of days to years.

Due to the limited length of the time series of measured irradiance and inconsistencies between different measurements, models of solar irradiance variation are particularly important.

This provides strong support for the hypothesis that solar irradiance variations are caused by changes in the amount and distribution of magnetic flux at the solar surface.