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[en] This work aims to investigate the effect of solar-geomagnetic activities on atmospheric circulation and to examine their influences on global surface temperature (GST). Used data are the sunspot number (Rz) as a solar activity index, geomagnetic activity index (aa), the North Atlantic Oscillation index (NAO), and GST. We have performed an extensive analysis by using the wavelet power spectra (WPS) and global wavelet spectra (GWS). Results from WPS showed that both NAO and GST exhibited periodicities of ~ 22 years and 11 years, indicating the imprint of solar activity on both parameters. Additionally, the WPS of NAO exhibited three dominant modes; firstly, periodicity of 2 to 4 years appeared in the time intervals: (1954–1967), (1987–1997), and (2007–2015), possibly related to El-Nino Southern Oscillation. Secondly, sporadic oscillation of 1 to 2.5 years observed during the whole period, which corresponding to quasi-biennial oscillation. Finally, oscillatory modes with high power on the band 7 to 8.5 years are observed on NAO spectrum: 7.6 years for the period (1872–1892) and 8.3 years for 1996–2005. This oscillatory mode with enhanced power in the 8.3 years has been detected significantly on the GWS of GST, indicating the influence of climatic pattern on GST. Our results showed that the solar-geomagnetic activities influence partially and indirectly on GST through atmospheric circulation pattern. (author)
[en] With the launch of the multi-governmental Nuclear Innovation: Clean Energy Future (NICE Future) initiative at the 9th Clean Energy Ministerial (CEM) in Copenhagen in May 2018, a new ministerial level discussion on clean energy that included nuclear energy was born. The NICE Future initiative envisions clean energy systems that take advantage of emissions-free nuclear energy in new and innovative ways to accelerate progress toward clean energy goals. Nuclear energy provides one-third of the world’s emissions-free electricity. Solar, wind, and nuclear are all emissions-free, but of these only nuclear energy provides clean electricity 24/7, and it has the smallest footprint. Recognizing that there is no one size fits all solution to the energy mix of each country, the NICE Future initiative was launched to show interested CEM members a range of options to consider for their clean energy systems relevant to their own domestic and international priorities.
[en] In this Letter we apply a methodology, recently proposed by Bourouaine & Perez (BP19), to interpret solar wind turbulent power spectra beyond the Taylor approximation (TA). The turbulent power spectra were measured using Helios spacecraft data near 0.6 au. We use the model proposed in BP19 to reproduce the field-perpendicular power spectrum E(k ⊥) of antisunward Alfvénic fluctuations in the plasma frame (where k ⊥ is the field-perpendicular wavenumber) from the corresponding measured frequency power spectrum along the sampling angle θ b, which is the angle between the local magnetic field and the sampling direction. Here ω = 2πf and f is the frequency of the time signal. Interestingly enough, we found that for all corresponding measured frequency power spectrum the reproduced field-perpendicular power spectrum E(k ⊥) is the same and independent of the considered sampling angle θ b. This finding is consistent with the fact that the analyzed turbulence is strong and highly anisotropic with (where is the field-parallel wavenumber). Furthermore, for this specific time signal we found that the commonly used TA is still approximately valid with the important difference that a broadening in k ⊥ for each angular frequency ω is present. This broadening can be described in the context of the methodology proposed in BP19.
[en] Magnetic clouds are large-scale transient structures in the solar wind with low plasma-β, low-amplitude magnetic field fluctuations, and twisted field lines with both ends often connected to the Sun. Their inertial-range turbulent properties have not been examined in detail. In this Letter, we analyze the normalized cross helicity, σ c, and residual energy, σ r, of plasma fluctuations in the 2018 November magnetic cloud observed at 0.25 au by the Parker Solar Probe. A low value of was present in the cloud core, indicating that wave power parallel and antiparallel to the mean field was approximately balanced, while the cloud’s outer layers displayed larger amplitude Alfvénic fluctuations with high values and σ r ∼ 0. These properties are discussed in terms of the cloud’s solar connectivity and local interaction with the solar wind. We suggest that low is likely a common feature of magnetic clouds given their typically closed field structure. Antisunward fluctuations propagating immediately upstream of the cloud had strongly negative σ r values.
[en] Traditionally, the solar magnetic field has been considered to have a negligible effect in the outer regions of the heliosphere. Recent works have shown that the solar magnetic field may play a crucial role in collimating the plasma in the heliosheath. Interstellar Boundary Explorer (IBEX) observations of the heliotail indicated a latitudinal structure varying with energy in the energetic neutral atom (ENA) fluxes. At energies ∼1 keV, the ENA fluxes show an enhancement at low latitudes and a deficit of ENAs near the poles. At energies >2.7 keV, ENA fluxes had a deficit within low latitudes, and lobes of higher ENA flux near the poles. This ENA structure was initially interpreted to be a result of the latitudinal profile of the solar wind during solar minimum. We extend the work of Kornbleuth et al. by using solar minimum–like conditions and the recently developed Solar-wind with Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD) model. The SHIELD model couples the magnetohydrodynamic plasma solution with a kinetic description of neutral hydrogen. We show that while the latitudinal profile of the solar wind during solar minimum contributes to the lobes in ENA maps, the collimation by the solar magnetic field is important in creating and shaping the two high-latitude lobes of enhanced ENA flux observed by IBEX. This is the first work to explore the effect of the changing solar magnetic field strength on ENA maps. Our findings suggest that IBEX is providing the first observational evidence of the collimation of the heliosheath plasma by the solar magnetic field.
[en] The origin of small-scale interplanetary magnetic flux-ropes (SIMFRs) and the relationship between SIMFRs and magnetic clouds (MCs) are still controversial. In this study, two populations of SMIFRs were collected, i.e., SIMFRs originating from the Sun (SIMFR-SUN) and those originating from the solar wind (SIMFR-SW). We defined the SIMFR-SUN (SIMFR-SW) as the SMIFRs that include (exclude) the counter-streaming suprathermal electrons and stay away from (close to) the heliospheric current sheet. After fitting with force-free flux-rope model, 52 SIMFR-SUN and 57 SIMFR-SW events observed by Advanced Composition Explorer from 1998 February to 2011 August were qualified. Using the approach of relating the measurements to their spatial position within the flux ropes, a comparative survey of plasma and composition characteristics inside the two populations of SIMFRs is presented. Results show that the two populations of SIMFRs have apparent differences. Compared with SIMFR-SW, SIMFR-SUN are MC-like, featuring lower central proton density, higher V rad, higher low-FIP element abundances, higher and more fluctuate average ion charge-states and the ion charge-state ratios that are related to the heating in the low corona. In addition, for the ion charge-state distributions inside SIMFR-SUN, the sunward side is higher than earthward, which might be caused by the flare heating during eruption. Moreover, both SIMFR-SUN and MCs show anticorrelation between plasma β and the He/P trend. These characteristics indicate that SIMFR-SUN and MCs are very likely to have identical origination. This study supports the two-source origin of SIMFRs, i.e., the solar corona and the solar wind.
[en] The present work examines and discusses the response of the atmospheric layers to solar variations, whereas the solar outputs are responsible for the changes in the Earth’s environment. Galactic cosmic ray rates (GCRs), solar cycle lengths (SCLs), sunspots (Rz), coronal index (CI) of solar activities, the aa geomagnetic activity index, total solar irradiance (TSI), CO2 concentrations, global surface temperatures (GSTs), the near-Earth of the northern and southern hemispheres temperatures have been examined. Our results displayed that every SCL has different behaviors to the sensitivity of GST, according to different modulations of GCRs by solar wind/helio-magnetic field parameters. Lower cosmic rays and higher solar irradiance and geomagnetic activity occur when solar activity increases. Furthermore, the average sensitivities of global temperature to geomagnetics aa and total solar irradiance and in turn low-level cloud cover are significant and real. Our results could indicate that geomagnetic disturbances, which driven by the solar wind, may influence global temperature. Both correlations of GST–Rz displayed the same behavior to the end of SC 22nd, and a great discrepancy is observed during the SC 23rd. The observed correlations of Rz with NH and SH temperatures displayed different behaviors. Four different mechanisms are involved in the direct/indirect effect of TSI variations on the Earth’s atmosphere and temperatures. (author)
[en] The radiation belts are regions in the near-Earth space where solar wind electrons are captured by the Earth's magnetic field. A portion of these electrons is continuously lost into the atmosphere where they cause ionization and chemical changes. Driven by the solar activity, the electron forcing leads to ozone variability in the polar stratosphere and mesosphere. Understanding the possible dynamical connections to regional climate is an ongoing research activity which supports the assessment of greenhouse-gas-driven climate change by a better definition of the solar-driven variability. In the context of the Coupled Model Intercomparison Project Phase 6 (CMIP6), energetic electron and proton precipitation is included in the solar-forcing recommendation for the first time. For the radiation belt electrons, the CMIP6 forcing is from a daily zonal-mean proxy model. This zonal-mean model ignores the well-known dependency of precipitation on magnetic local time (MLT), i.e. its diurnal variability. Here we use the Whole Atmosphere Community Climate Model with its lower-ionospheric-chemistry extension (WACCM-D) to study effects of the MLT dependency of electron forcing on the polar-ozone response. We analyse simulations applying MLT-dependent and MLT-independent forcings and contrast the resulting ozone responses in monthly-mean data as well as in monthly means at individual local times. We consider two cases: (1) the year 2003 and (2) an extreme, continuous forcing. Our results indicate that the ozone responses to the MLT-dependent and the MLT-independent forcings are very similar, and the differences found are small compared to those caused by the overall uncertainties related to the representation of electron forcing in climate simulations. We conclude that the use of daily zonal-mean electron forcing will provide an accurate ozone response in long-term climate simulations.
[en] We at the IEA are very fortunate experts, because we have all the energy data at our fingertips; make our judgements, recommendations, analysis based on data. When we look at the last year, 2018 energy data, we see a few interesting points: number one, global energy demands last year increased the strongest in the last ten years, about 2.3%, a very strong growth. More importantly, electricity demand increased even two times higher than the energy demand. This is an ongoing trend, and we expect this trend to continue and the growth of electricity is very, very pertinent and much higher than energy demand. As such, we believe electricity is the future. But coming back to 2018 again, despite the growth in renewable energies, in solar, wind and others, we saw last year global emissions increased and reached a record high; 2018 global CO2 emissions reached a record high. And as such a key message for me is that there is a growing and dangerous disconnect between the climate ambitions reports, meetings, government intentions and what is happening in the real life. More and more reports, stronger ambitions, more speeches — like mine here — and we saw that the emissions still do increase. Therefore, we believe, and we believe very strongly at the IEA, that we have to look at all clean energy technologies, to make the most of those options. Renewable energies, solar and wind, are definitely important parts of this picture, but we also think that the nuclear power, carbon capture, utilization and storage, and other clean energy technologies are important.