Response of cloud condensation nuclei (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mo>&gt;</mml:mo><mml:mn>50</mml:mn><mml:mtext> nm</mml:mtext></mml:math>) to changes in ion-nucleation

Svensmark, Henrik; Enghoff, Martin Andreas Bødker; Pedersen, Jens Olaf Pepke

doi:10.1016/j.physleta.2013.07.004

Cited by 64 publications

(34 citation statements)

References 32 publications

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“…A precise coupling mechanism remains to be found. Other mechanisms have been considered: galactic cosmic rays are strongly modulated by solar activity (Svensmark, 1998;Svensmark et al, 2013). One could be tempted to link the~1 year phase lag ( Figure 9) with that seen in cosmic rays (e.g., Usoskin et al, 1997).…”

Section: Discussionmentioning

confidence: 99%

A Solar Signature in Many Climate Indices

2019

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We first apply singular spectrum analysis (SSA) to the international sunspot number (1849–2015) and the count of polar faculae (1906–2006). The SSA method finds 22‐, 11‐, and 5.5‐year components as the first eigenvectors of these solar activity proxies. We next apply SSA to the 10 Madden‐Julian oscillation (MJO; 1978–2016) indices. The first, most intense component SSA finds in all MJO indices has either a period of 5.5 or 11 years. The longer‐term modulation of amplitude is on the order of one third of the total variation. The 5.5‐year SSA component 1 of most MJO indices moreover follows the decreasing amplitude of solar cycles. We then apply SSA to climate indices Pacific Decadal Oscillation, El Nino Southern Oscillation precipitation index, Arctic Oscillation, Atlantic Multidecadal oscillation, Tropical Southern Atlantic oscillation, Western Hemisphere Warm Pool, and Brazil and Sahel rainfalls. We find that the first SSA eigenvectors are all combinations of rather pure 11, 5.5, and 3.6‐year pseudo‐cycles. The 5.5‐year component is frequently observed and is particularly important and sharp in the series in which it appears. All these periods have long been attributed to solar activity, and this by itself argues for the existence of a strong link between solar activity and climate. The mechanisms of coupling must be complex and probably nonlinear but they remain to be fully understood (UV radiation, solar wind, and galactic cosmic rays being the most promising candidates). We propose as a first step a Kuramoto model of nonlinear coupling that generates phase variations compatible with the observed ones.

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Section: Discussionmentioning

confidence: 99%

A Solar Signature in Many Climate Indices

2019

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“…Given independent correlations observed between CRF variations and climate on different time scales [e.g., Shaviv, 2002;Svensmark et al, 2009], this mechanism involving clouds could potentially explain the amplified solar forcing or part of it. Interestingly, several experiments indicate that atmospheric ionization can increase the nucleation of condensation nuclei [Svensmark et al, 2005;Kirkby, 2011] and help the growth to cloud condensation nuclei [Svensmark et al, 2013]. Nevertheless, it should be noted that the solar/CRF/climate link 10.1002/2014JA020732 is still debated in the literature, partially because an exact chemical or physical mechanism is still missing and partially because some of the empirical evidence is disputed.…”

Section: Introductionmentioning

confidence: 99%

The solar and Southern Oscillation components in the satellite altimetry data

Howard¹,

Shaviv

Svensmark

2015

JGR Space Physics

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With satellite altimetry data accumulating over the past two decades, the mean sea level (MSL) can now be measured to unprecedented accuracy. We search for physical processes which can explain the sea level variations and find that at least 70% of the variance in the annually smoothed detrended altimetry data can be explained as the combined effect of both the solar forcing and the El Niño-Southern Oscillation (ENSO). The phase of the solar component can be used to derive the different steric and eustatic contributions. We find that the peak to peak radiative forcing associated with the solar cycle is 1.33 ± 0.34 W/m 2 , contributing a 4.4 ± 0.8 mm variation. The slow eustatic component (describing, for example, the cryosphere and large bodies of surface water) has a somewhat smaller peak to peak amplitude of 2.4 ± 0.6 mm. Its phase implies that warming the oceans increases the ocean water loss rate. Additional much smaller terms include a steric feedback term and a fast eustatic term. The ENSO contributes a peak to peak variation of 5.5 ± 0.8 mm, predominantly through a direct effect on the MSL and significantly less so indirectly through variations in the radiative forcing.

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“…The total solar irradiance has a relative decrease in connection with FDs of the order of 10 −3 , which is too small to have a thermodynamic impact on timescales of a few days. The results demonstrate that there is a real influence of FDs on clouds probably through ions.Experimentally, it has been shown that ions do promote the formation of new small (3 nm sized) aerosols [Svensmark et al, 2007;Kirkby et al, 2011], and one experiment suggests that ions also help the growth of aerosols to cloud condensation nuclei sizes (>50 nm) [Svensmark et al, 2013]. However, from a modeling point of view, it is uncertain whether a variation in ion-induced nucleation may translate into an observable change Last, the results are discussed in section 7 and placed in context of possible mechanisms involving changes in the GCR flux, the Total Solar Irradiance (TSI), or UV light.…”

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The response of clouds and aerosols to cosmic ray decreases

et al. 2016

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A method is developed to rank Forbush decreases (FDs) in the galactic cosmic ray radiation according to their expected impact on the ionization of the lower atmosphere. Then a Monte Carlo bootstrap‐based statistical test is formulated to estimate the significance of the apparent response in physical and microphysical cloud parameters to FDs. The test is subsequently applied to one ground‐based and three satellite‐based data sets. Responses (>95%) to FDs are found in the following parameters of the analyzed data sets. AERONET: Ångström exponent (cloud condensation nuclei changes), SSM/I: liquid water content, International Satellite Cloud Climate Project (ISCCP): total, high, and middle, IR‐detected clouds over the oceans, Moderate Resolution Imaging Spectroradiometer (MODIS): cloud effective emissivity, cloud optical thickness, liquid water, cloud fraction, liquid water path, and liquid cloud effective radius. Moreover, the responses in MODIS are found to correlate positively with the strength of the FDs, and the signs and magnitudes of the responses agree with model‐based expectations. The effect is mainly seen in liquid clouds. An impact through changes in UV‐driven photo chemistry is shown to be negligible and an impact via UV absorption in the stratosphere is found to have no effect on clouds. The total solar irradiance has a relative decrease in connection with FDs of the order of 10−3, which is too small to have a thermodynamic impact on timescales of a few days. The results demonstrate that there is a real influence of FDs on clouds probably through ions.

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Response of cloud condensation nuclei (>50 nm) to changes in ion-nucleation

Cited by 64 publications

References 32 publications

A Solar Signature in Many Climate Indices

A Solar Signature in Many Climate Indices

The solar and Southern Oscillation components in the satellite altimetry data

The response of clouds and aerosols to cosmic ray decreases

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