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"Solar Effects"
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My best pop-up space book
Introduces the solar system and explains how astronauts explore space, in a book that allows the reader to push a button to listen to noisy rocket sounds.
Book
The Sun's Influence on Climate
The Earth's climate system depends entirely on the Sun for its energy. Solar radiation warms the atmosphere and is fundamental to atmospheric composition, while the distribution of solar heating across the planet produces global wind patterns and contributes to the formation of clouds, storms, and rainfall. The Sun’s Influence on Climate provides an unparalleled introduction to this vitally important relationship.This accessible primer covers the basic properties of the Earth’s climate system, the structure and behavior of the Sun, and the absorption of solar radiation in the atmosphere. It explains how solar activity varies and how these variations affect the Earth’s environment, from long-term paleoclimate effects to century timescales in the context of human-induced climate change, and from signals of the 11-year sunspot cycle to the impacts of solar emissions on space weather in our planet’s upper atmosphere.Written by two of the leading authorities on the subject, The Sun’s Influence on Climate is an essential primer for students and nonspecialists alike.
eBook
The 6 September 2017 X-Class Solar Flares and Their Impacts on the Ionosphere, GNSS, and HF Radio Wave Propagation
On 6 September 2017, the Sun emitted two significant solar flares (SFs). The first SF, classified X2.2, peaked at 09:10 UT. The second one, X9.3, which is the most intensive SF in the current solar cycle, peaked at 12:02 UT and was accompanied by solar radio emission. In this work, we study ionospheric response to the two X-class SFs and their impact on the Global Navigation Satellite Systems and high-frequency (HF) propagation. In the ionospheric absolute vertical total electron content (TEC), the X2.2 SF caused an overall increase of 2-4 TECU on the dayside. The X9.3 SF produced a sudden increase of 8-10 TECU at midlatitudes and of 15-16 TECU enhancement at low latitudes. These vertical TEC enhancements lasted longer than the duration of the EUV emission. In TEC variations within 2-20 min range, the two SFs provoked sudden increases of 0.2 TECU and 1.3 TECU. Variations in TEC from geostationary and GPS/GLONASS satellites show similar results with TEC derivative of 1.3-1.7 TECU/min for X9.3 and 0.18-0.24 TECU/min for X2.2 in the subsolar region. Further, analysis of the impact of the two SFs on the Global Navigation Satellite Systems-based navigation showed that the SF did not cause losses-of-lock in the GPS, GLONASS, or Galileo systems, while the positioning error increased by 3 times in GPS precise point positioning solution. The two X-class SFs had an impact on HF radio wave propagation causing blackouts at <30 MHz in the subsolar region and <15 MHz in the postmidday sector.
Journal Article
Evaluation of the Solar Energy Nowcasting System (SENSE) during a 12-Months Intensive Measurement Campaign in Athens, Greece
Energy nowcasting is a valuable asset in managing energy loads and having real-time information on solar irradiation availability. In this study, we evaluate the spectrally integrated outputs of the SENSE system for solar irradiance nowcasting for the period of the ASPIRE (atmospheric parameters affecting spectral solar irradiance and solar energy) campaign (December 2020–December 2021) held in Athens, Greece. For the needs of the campaign, several ground-based instruments were operating, including two pyranometers, a pyrheliometer, a cloud camera, a CIMEL sunphotometer, and a precision spectral radiometer (PSR). Global horizontal irradiance (GHI) estimations were more accurate than direct normal irradiance (DNI). SENSE estimations are provided every 15 min, but when comparing bigger time intervals (hours-days), the statistics improved. A dedicated assessment of the SENSE’s inputs is performed in respect to ground-based retrievals, considering cloud conditions (from a sky imager), AOD, and precipitable water vapor from AERONET. The factor that established the larger errors was the visibility of the solar disc, which cannot be defined by the available sources of model inputs. Additionally, there were discrepancies between the satellite estimation of the clouds and the ground picture, which caused deviations in results. AOD differences affected more the DNI.
Journal Article
On the Possibility of Modeling the IMF By-Weather Coupling through GEC-Related Effects on Cloud Droplet Coalescence Rate
The meteorological response to the fluctuation of the interplanetary magnetic field (IMF), known as the Mansurov effect, is well established. It is hypothesized that the IMF By fluctuation can modulate the atmospheric global electric circuit (GEC) over the polar regions and affect surface meteorology. The influence of electric charges on the rate of droplet coalescence in fair-weather clouds is one of several cloud microphysical mechanisms that have been hypothesized to be involved. However, although meteorological effects associated with IMF By have been observed, the role of cloud droplet coalescence in this solar–weather coupling mechanism has not yet been confirmed. In addition, studies demonstrating the solar wind-driven effects are based on observations without using global climate models to support the IMF By-weather linkage. In this study, we investigate the Mansurov effect over the period 1999–2002 using ensemble experiments modeled with the chemistry-climate model (CCM) SOCOLv3 (SOlar Climate Ozone Links, version 3.0). Using observed IMF By, we model its effect on ground-level air pressure and temperature to examine one of the proposed GEC-cloud hypotheses: that surface meteorology response on IMF By fluctuations occurs through the Jz-associated intensification of cloud droplet coalescence rate. The results showed that we cannot explain and confirm the hypothesis that the rate of cloud droplet coalescence is an intermediate link for the IMF By-weather coupling. Anomalies in surface air pressure and temperature from the control run, where IMF By is omitted, do not robustly differ from experiments in which the dependence of cloud droplet coalescence rate on IMF By is included. In addition, the standard deviation of anomalies in surface air pressure and temperature between ensemble members is consistent with the magnitude of the observed effect even in the control run, suggesting that the model has a strong internal variability that prevents the IMF By effect from being properly detected in the model.
Journal Article
Effect of Solar Parameters on Geomagnetic Storm Formation in the Ascending Phase of the 25th Solar Cycle
In this paper, starting from solar storms, which are the main cause of geomagnetic storms, the effects of the speed (v) and density (Np) of solar plasma coming to the Earth on geomagnetic storms are investigated. During the ascending phase of the 25th solar cycle (2021 – 2022), various geomagnetic storms from G1 to G4 were examined. Multiple linear regression models are created to examine the effects of solar parameters that cause changes in geomagnetic storm processes. The effects of the speed and charge density of solar wind, coronal mass ejections (CMEs), corotating interaction regions (CIRs), and CME-CME interactions on the Dst index, which reflects disturbances in the Earth’s magnetic field and the scale of geomagnetic storms, are statistically analyzed. It is determined that a one-unit change in speed in 82 geomagnetic storms in the statistical models created a decrease in Dst of approximately −0.25 nT. In contrast, it is determined that a unit increase in particle density also reduces the effect and duration of a geomagnetic storm. However, if there is an increase in density during the main phase of the storm, then the storm level increases. We believe that our results will significantly contribute to predicting the formation of geomagnetic storms and their possible effects on space weather.
Journal Article
A Study of Solar Flare Effects on the Geomagnetic Field Components during Solar Cycles 23 and 24
In this paper, we investigated the impact of solar flares on the horizontal (H), eastward (Y) and vertical (Z) components of the geomagnetic field during solar cycles 23 and 24 (SC23/24) using data of magnetometer measurements on the sunlit side of the Earth. We examined the relation between sunspot number and solar flare occurrence of various classes during both cycles. During SC23/24, we obtained correlation coefficient of 0.93/0.97, 0.96/0.96 and 0.60/0.56 for C-class, M-class and X-class flare, respectively. The three components of the geomagnetic field reached a peak a few minutes after the solar flare occurrence. Generally, the magnetic crochet of the H component was negative between the mid-latitudes and Low-latitudes in both hemispheres and positive at low latitudes. By contrast, the analysis of the latitudinal variation of the Y and Z components showed that unlike the H component, their patterns of variations were not coherent in latitude. The peak amplitude of solar flare effect (sfe) on the various geomagnetic components depended on many factors including the local time at the observing station, the solar zenith angle, the position of the station with respect to the magnetic equator, the position of solar flare on the sun and the intensity of the flare. Thus, these peaks were stronger for the stations around the magnetic equator and very low when the geomagnetic field components were close to their nighttime values. Both cycles presented similar monthly variations with the highest sfe value (ΔHsfe = 48.82 nT for cycle 23 and ΔHsfe = 24.68 nT for cycle 24) registered in September and lowest in June for cycle 23 (ΔHsfe = 8.69 nT) and July for cycle 24 (ΔHsfe = 10.69 nT). Furthermore, the sfe was generally higher in cycle 23 than in cycle 24.
Journal Article
Long Term Global Ionospheric Total Electron Content Trend Analysis
Simulations based on physical models of the thermosphere‐ionosphere system suggest that the ionosphere will sink as the thermosphere cools and contracts in response to increasing greenhouse gas concentrations. As a consequence, long‐term trends can be expected in ionospheric parameters such as: total electron content (TEC), the critical frequency of the F2 layer, foF2, and its peak height, hmF2. Since early 1990s, foF2 and hmF2, though to a lesser extent, have been widely analyzed to find these trends. This study shows long‐term TEC trends for the period 1999–2023 from available global International GNSS service TEC maps. Using F30, F10.7 or MgII as proxies to filter out the effect of solar EUV, the trends are negative, not only for the mean global value but also for most regions with very few exceptions. This would align with the greenhouse effect hypothesis, even though our results show higher negative trend values than expected theoretically. Plain Language Summary The Earth's ionosphere presents long‐term trends besides regular changes such as daily and seasonal, and irregular variations of transient character. Many studies suggest that the long‐term increase in greenhouse gas concentrations will produce a global cooling in the upper atmosphere together with the global warming in the troposphere. Therefore, long‐term trends can be expected in the ionosphere total electron content (TEC), the critical frequency of the F2 layer, foF2, and its peak height, hmF2, which are the three most important ionospheric parameters used in several applications. TEC measurements have the advantage over other parameters that characterize the upper atmosphere having 24 × 365 worldwide coverage thanks to the continuous International GNSS service (IGS). Trends in the ionosphere are much weaker than those associated with the solar cycle, thus its effects were removed using different solar EUV radiation proxies. The trends are negative, as expected, not only for the mean global value case but also for most of the regional values with very few exceptions. Key Points Trend depends on the solar EUV proxy used for filtering being most negative with MgII and non‐significant with SN Based on recommended solar proxies, noon total electron content (TEC) global average reveal a negative significant trend along 1999–2023 The negative trend of the global TEC at noon is much more pronounced than the theoretical prediction
Journal Article
Energy Meteorology for the Evaluation of Solar Farm Thermal Impacts on Desert Habitats
This work addresses challenges and opportunities in the evaluation of solar power plant impacts, with a particular focus on thermal effects of solar plants on the environment and vice-versa. Large-scale solar power plants are often sited in arid or desert habitats, which tend to include fauna and flora that are highly sensitive to changes in temperature and humidity. Our understanding of both shortwave (solar) and longwave (terrestrial) radiation processes in solar power plants is complete enough to render the modeling of radiation fluxes with high confidence for most applications. In contrast to radiation, the convective environment in large-scale solar power plants is much more difficult to characterize. Wind direction, wind speed, turbulence intensity, dust concentration, ground condition, panel configuration density, orientation and distribution throughout the solar field, all affect the local environment, the balance between radiation and convection, and in turn, the performance and thermal impact of solar power plants. Because the temperatures of the two sides of photovoltaic (PV) panels depend on detailed convection–radiation balances, the uncertainty associated with convection affects the heat and mass transfer balances as well. Those balances are critically important in estimating the thermal impact of large-scale solar farms on local habitats. Here we discuss outstanding issues related with these transfer processes for utility-scale solar generation and highlight potential pathways to gain useful knowledge about the convective environment directly from solar farms under operating conditions.
Journal Article
First Observations of a Geomagnetic Superstorm With a Sub‐L1 Monitor
Forecasting the geomagnetic effects of solar coronal mass ejections (CMEs) is currently an unsolved problem. CMEs, responsible for the largest values of the north‐south component of the interplanetary magnetic field, are the key driver of intense and extreme geomagnetic activity. Observations of southward interplanetary magnetic fields are currently only accessible directly through in situ measurements by spacecraft in the solar wind. On 10–12 May 2024, the strongest geomagnetic storm since 2003 took place, caused by five interacting CMEs. We clarify the relationship between the CMEs, their solar source regions, and the resulting signatures at the Sun–Earth L1 point observed by the ACE spacecraft at 1.00 AU. The STEREO‐A spacecraft was situated at 0.956 AU and 12.6° ^{\\circ}$ west of Earth during the event, serving as a fortuitous sub‐L1 monitor providing interplanetary magnetic field measurements of the solar wind. We demonstrate an extension of the prediction lead time, as the shock was observed 2.57 hr earlier at STEREO‐A than at L1, consistent with the measured shock speed at L1, 710 kms−1 $\\,{\\mathrm{s}}^{-1}$, and the radial distance of 0.043 AU. By deriving the geomagnetic indices based on the STEREO‐A beacon data, we show that the strength of the geomagnetic storm would have been decently forecasted, with the modeled minimum SYM‐H=−478.5 $\\,=-\\,478.5$ nT, underestimating the observed minimum by only 8%. Our study sets an unprecedented benchmark for future mission design using upstream monitoring for space weather prediction.
Journal Article