Publication Search Results

Search Results

Showing 1-20 of about 24 results.
Latitudinal insolation gradients throughout the Holocene II - High frequency variationsCionco, Rodolfo G.Soon, Willie W. -HElias, Ana G.Quaranta, Nancy E.DOI: info:10.1016/j.asr.2020.07.008v. 661992–2000
Cionco, Rodolfo G., Soon, Willie W. -H, Elias, Ana G., and Quaranta, Nancy E. 2020. "Latitudinal insolation gradients throughout the Holocene II - High frequency variations." Advances in Space Research 66:1992– 2000. https://doi.org/10.1016/j.asr.2020.07.008
ID: 157463
Type: article
Authors: Cionco, Rodolfo G.; Soon, Willie W. -H; Elias, Ana G.; Quaranta, Nancy E.
Abstract: In a first paper, we presented an in-depth discussion and a computational method (free of the calendar problem) to reckon any kind of latitudinal insolation gradients, LIGs, throughout the Holocene and up to CE 3000. One of the main insights from this exact definition of LIGs is that, unlike what is argued in prior works, during the Holocene, a general classification of LIGs in terms of obliquity signal or climatic precession variations is much more complex, even in summertime. It is especially evident in the Southern Hemisphere, where summer half-year LIGs evolve under the relatively stronger modulation by climatic precession. In this work, the short-term periodicities (high frequency variations in time domain) of all these LIGs are studied by means of the multitaper spectral analysis. The goal is to get more insights on the competing effects between obliquity and climatic precession during the Holocene, and to know how the relative intensity of the obliquity's periodicities is when compared to the main spectral peaks produced by the climatic precession effects at short time scales (e.g., from annual to decadal bands). Our main result is the clarification of the role of the 18.63 yr periodicity originated in the well known retrograding cycle of the Moons' orbit. We found that this lunar cycle is always present at a 99 % significance level in all the analysed LIGs, even in winter with solar cycle included. The conceptual explanation of this persistence is based on the fact that all accurate short-term orbital forcing calculation must include the lunar nodal cycle even in climatic precession variations. We propose to use more specific definitions when short-term orbital variations are taken into account in describing Milanković forcing.
On the calculation of latitudinal insolation gradients throughout the HoloceneCionco, Rodolfo G.Soon, Willie W. -HQuaranta, Nancy E.DOI: info:10.1016/j.asr.2020.04.030v. 66720–742
Cionco, Rodolfo G., Soon, Willie W. -H, and Quaranta, Nancy E. 2020. "On the calculation of latitudinal insolation gradients throughout the Holocene." Advances in Space Research 66:720– 742. https://doi.org/10.1016/j.asr.2020.04.030
ID: 157465
Type: article
Authors: Cionco, Rodolfo G.; Soon, Willie W. -H; Quaranta, Nancy E.
Abstract: In paleoclimatology, the concept of latitudinal insolation gradients (LIGs), reckoned in various ways, has received increasing attention regarding glacial/inter-glacial climatic transitions and oscillations. In particular, the Holocene, which permits the reconstruction of past climatic proxies with an increasingly finer spatial and temporal resolutions, has provided evidence that suggests that LIGs are a key forcing on climate at different timescales. Nevertheless, LIGs' own dynamics (chiefly their variations in relation to astronomical parameters and geographical zones) and even basic definitions, have not been properly investigated, especially during the last part of the present geological epoch. The main reason is the lack of broadly accessible, theoretical insolation data that account for short-term orbital variations (i.e., for describing sub-Milanković-orbital forcing during the Holocene). Based on our latest astronomical-orbital solutions, we present an in-depth discussion on the calculation of LIGs and their variations all through the Holocene and 1 kyr into the future. Our results show a much more complex variety and behaviour of LIGs than those that were shown previously. We report that during the studied period, daily LIGs in summer, around the solstitial days (both hemispheres), are strongly modulated by obliquity only at mid-latitude band, whereas at tropical and polar bands LIGs are modulated by "precession". Summer half-year LIGs for the Northern Hemisphere show a marked modulation in out-of-phase sense with obliquity, just for the mid-latitude and polar bands. Surprisingly, this competing effect between "precession" and obliquity also produces the fact that the southern counterpart of these LIGs are more modulated by "precession" than obliquity. In cases involving inter-band latitudes or different intra-annual lapses, they need to be examined separately and carefully and the results could be very different from traditional presumptions. Our novel results and study are based on the precise estimation of the duration of the orbital interval considered in the definition of LIGs. Our new study also avoids the difficulties of insolation calculations regarding the relationship between orbital longitudes and time.
The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESSMetcalfe, Travis S.van Saders, Jennifer L.Basu, SarbaniBuzasi, DerekChaplin, William J.Egeland, RickyGarcia, Rafael A.Gaulme, PatrickHuber, DanielReinhold, TimoSchunker, HannahStassun, Keivan G.Appourchaux, ThierryBall, Warrick H.Bedding, Timothy R.Deheuvels, SébastienGonzález-Cuesta, LucíaHandberg, RasmusJiménez, AntonioKjeldsen, HansLi, TandaLund, Mikkel N.Mathur, SavitaMosser, BenoitNielsen, Martin B.Noll, AnthonyÇelik Orhan, ZeynepÖrtel, SibelSantos, Ângela R. G.Yildiz, MutluBaliunas, SallieSoon, WillieDOI: info:10.3847/1538-4357/aba963v. 900154
Metcalfe, Travis S., van Saders, Jennifer L., Basu, Sarbani, Buzasi, Derek, Chaplin, William J., Egeland, Ricky, Garcia, Rafael A., Gaulme, Patrick, Huber, Daniel, Reinhold, Timo, Schunker, Hannah, Stassun, Keivan G., Appourchaux, Thierry, Ball, Warrick H., Bedding, Timothy R., Deheuvels, Sébastien, González-Cuesta, Lucía, Handberg, Rasmus, Jiménez, Antonio, Kjeldsen, Hans, Li, Tanda, Lund, Mikkel N., Mathur, Savita, Mosser, Benoit, Nielsen, Martin B. et al. 2020. "The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESS." The Astrophysical Journal 900:154. https://doi.org/10.3847/1538-4357/aba963
ID: 157464
Type: article
Authors: Metcalfe, Travis S.; van Saders, Jennifer L.; Basu, Sarbani; Buzasi, Derek; Chaplin, William J.; Egeland, Ricky; Garcia, Rafael A.; Gaulme, Patrick; Huber, Daniel; Reinhold, Timo; Schunker, Hannah; Stassun, Keivan G.; Appourchaux, Thierry; Ball, Warrick H.; Bedding, Timothy R.; Deheuvels, Sébastien; González-Cuesta, Lucía; Handberg, Rasmus; Jiménez, Antonio; Kjeldsen, Hans; Li, Tanda; Lund, Mikkel N.; Mathur, Savita; Mosser, Benoit; Nielsen, Martin B.; Noll, Anthony; Çelik Orhan, Zeynep; Örtel, Sibel; Santos, Ângela R. G.; Yildiz, Mutlu; Baliunas, Sallie; Soon, Willie
Abstract: Most previous efforts to calibrate how rotation and magnetic activity depend on stellar age and mass have relied on observations of clusters, where isochrones from stellar evolution models are used to determine the properties of the ensemble. Asteroseismology employs similar models to measure the properties of an individual star by matching its normal modes of oscillation, yielding the stellar age and mass with high precision. We use 27 days of photometry from the Transiting Exoplanet Survey Satellite to characterize solar-like oscillations in the G8 subgiant of the 94 Aqr triple system. The resulting stellar properties, when combined with a reanalysis of 35 yr of activity measurements from the Mount Wilson HK project, allow us to probe the evolution of rotation and magnetic activity in the system. The asteroseismic age of the subgiant agrees with a stellar isochrone fit, but the rotation period is much shorter than expected from standard models of angular momentum evolution. We conclude that weakened magnetic braking may be needed to reproduce the stellar properties, and that evolved subgiants in the hydrogen shell-burning phase can reinvigorate large-scale dynamo action and briefly sustain magnetic activity cycles before ascending the red giant branch.
Waldmeier Effect in Stellar CyclesGarg, SuyogKarak, Bidya BinayEgeland, RickySoon, WillieBaliunas, SallieDOI: info:10.3847/1538-4357/ab4a17v. 886132
Garg, Suyog, Karak, Bidya Binay, Egeland, Ricky, Soon, Willie, and Baliunas, Sallie. 2019. "Waldmeier Effect in Stellar Cycles." The Astrophysical Journal 886:132. https://doi.org/10.3847/1538-4357/ab4a17
ID: 154510
Type: article
Authors: Garg, Suyog; Karak, Bidya Binay; Egeland, Ricky; Soon, Willie; Baliunas, Sallie
Abstract: One of the most robust features of the solar magnetic cycle is that the stronger cycles rise faster than the weaker ones. This is popularly known as the Waldmeier Effect, which has been known for more than 100 yr. This fundamental feature of the solar cycle has not only practical implications, e.g., in predicting the solar cycle, but also implications in understanding the solar dynamo. Here we ask whether the Waldmeier Effect exists in other Sun-like stars. To answer this question, we analyze the Ca II H and K S-index from Mount Wilson Observatory for 21 Sun-like G─K stars. We specifically check two aspects of Waldmeier Effect, namely, (1) WE1: the anticorrelation between the rise times and the peaks and (2) WE2: the positive correlation between rise rates and amplitudes. We show that, except for HD 16160, HD 81809, HD 155886, and HD 161239, all stars considered in the analysis show WE2, while WE1 is found to be present only in some of the stars studied. Furthermore, the WE1 correlation is weaker than the WE2. Both WE1 and WE2 exist in the solar S-index as well. Similar to the solar cycles, the magnetic cycles of many stars are asymmetric about their maxima. The existence of the Waldmeier Effect and asymmetric cycles in Sun-like stars suggests that the dynamo mechanism which operates in the Sun is also operating in other stars.
Temperature seasonality and ENSO variability in the northern South China Sea during the Medieval Climate Anomaly interval derived from the Sr/Ca ratios of Tridacna shellLiu, ChengchengYan, HongFei, HaobaiMa, XiaolinZhang, WenchaoShi, GeSoon, WillieDodson, JohnAn, ZhishengDOI: info:10.1016/j.jseaes.2019.103880v. 180103880
Liu, Chengcheng, Yan, Hong, Fei, Haobai, Ma, Xiaolin, Zhang, Wenchao, Shi, Ge, Soon, Willie, Dodson, John, and An, Zhisheng. 2019. "Temperature seasonality and ENSO variability in the northern South China Sea during the Medieval Climate Anomaly interval derived from the Sr/Ca ratios of Tridacna shell." Journal of Asian Earth Sciences 180:103880. https://doi.org/10.1016/j.jseaes.2019.103880
ID: 154260
Type: article
Authors: Liu, Chengcheng; Yan, Hong; Fei, Haobai; Ma, Xiaolin; Zhang, Wenchao; Shi, Ge; Soon, Willie; Dodson, John; An, Zhisheng
Abstract: The nature of how the El Niño-Southern Oscillation (ENSO) and its seasonality respond to warmer climate is critical knowledge to predict future climates under the expected anthropogenic warming scenario. In this study, a sub-fossil Tridacna gigas specimen was collected from the northern SCS and AMS14C dating suggested that the animal lived around AD 1099, during the Medieval Climate Anomaly (MCA) interval, the most recent natural warm period of the late Holocene. Monthly Sr/Ca ratios were determined by the ICP-OES measurements and a 30-year long SST record was calculated based on a Sr/Ca-SST calibration equation. The results showed that the SST seasonality for this 30-year window around AD 1099 was about 3.11 °C, which is smaller than the modern warm period (i.e., about 4.36 °C for AD 1994 ∼ 2005 interval). This new result is consistent with another published Tridacna gigas record that was dated around AD 990 from the northern SCS. The signals of ENSO activity were also extracted from the reconstructed SST record and statistical analyses yielded 9 El Niño events and 8 La Niña events within the 30-year record, indicating that the frequency of ENSO activity around AD 1099 was similar to the modern instrumental period.
Reply to Li & Yang's comments on 'Comparing the current and early 20th century warm periods in China'Soon, Willie Wei-HockConnolly, RonanConnolly, MichaelO'Neill, PeterZheng, JingyunGe, QuanshengHao, ZhixinYan, HongDOI: info:10.1016/j.earscirev.2019.102950v. 198102950
Soon, Willie Wei-Hock, Connolly, Ronan, Connolly, Michael, O'Neill, Peter, Zheng, Jingyun, Ge, Quansheng, Hao, Zhixin, and Yan, Hong. 2019. "Reply to Li & Yang's comments on "Comparing the current and early 20th century warm periods in China"." Earth Science Reviews 198:102950. https://doi.org/10.1016/j.earscirev.2019.102950
ID: 154586
Type: article
Authors: Soon, Willie Wei-Hock; Connolly, Ronan; Connolly, Michael; O'Neill, Peter; Zheng, Jingyun; Ge, Quansheng; Hao, Zhixin; Yan, Hong
Abstract: From a cursory reading of Li & Yang's comments [Li and Yang, 2019, henceforth LY2019] on our recent review article, Soon et al. (2018) [henceforth S2018], some readers might think that LY2019 is somehow disputing our analysis and conclusions. Specifically, they claim to offer "some comments on the arbitrary or deductive conclusions ofSoon et al. (2018)as [sic.] the following five aspects…"
Covariations of chromospheric and photometric variability of the young Sun analogue HD 30495: evidence for and interpretation of mid-term periodicitiesSoon, WillieVelasco Herrera, V. M.Cionco, R. G.Qiu, S.Baliunas, SallieEgeland, R.Henry, G. W.Charvátová, I.DOI: info:10.1093/mnras/sty3290v. 4832748–2757
Soon, Willie, Velasco Herrera, V. M., Cionco, R. G., Qiu, S., Baliunas, Sallie, Egeland, R., Henry, G. W., and Charvátová, I. 2019. "Covariations of chromospheric and photometric variability of the young Sun analogue HD 30495: evidence for and interpretation of mid-term periodicities." Monthly Notices of the Royal Astronomical Society 483:2748– 2757. https://doi.org/10.1093/mnras/sty3290
ID: 150530
Type: article
Authors: Soon, Willie; Velasco Herrera, V. M.; Cionco, R. G.; Qiu, S.; Baliunas, Sallie; Egeland, R.; Henry, G. W.; Charvátová, I.
Abstract: This study reports the synchronization between the chromospheric and photometric variability at time-scale of about 1.6-1.8 yr as observed for the young, rapidly rotating solar analogue HD 30495. In addition, HD 30495 may be presenting evidence of surface differential rotation at time-scales of about 11 d and 21 d, as well as the sunspot-like decadal cycles at 11-12 yr or so. We apply a new gapped wavelet method of time-frequency analysis for studying the variability in a new composite of the chromospheric S-index (1967-2018) and the longest photometric Δ(b + y)/2 index (1993-2018). We discuss and interpret our results in relation to other observed mid-term periodicities roughly of the same time-scales that had been found recently from not only chromospheric and photospheric activity indices but also from coronal X-ray emissions as observed in a considerably large set of stellar samples including those young Sun analogues from the Kepler satellite project. Thus, there is an apparent universality of such mid-term activity modulation time-scales as this solar-stellar magnetic phenomenon is well observed directly for a host of solar activity related indices covering the photopsheric, chromospheric, coronal, and even the heliospheric (utilizing the measures of incoming galactic cosmic rays as a probe of activity variations) activity records. This is why we made a further attempt to interpret the results in search of a realistic generation mechanism as well as spatio-temporal persistency of the phenomenon under a wide scenario of dynamo simulations.
Lunar fingerprints in the modulated incoming solar radiation: In situ insolation and latitudinal insolation gradients as two important interpretative metrics for paleoclimatic data records and theoretical climate modelingCionco, Rodolfo GustavoValentini, José ErnestoQuaranta, Nancy EstherSoon, Willie W. -HDOI: info:10.1016/j.newast.2017.08.003v. 5896–106
Cionco, Rodolfo Gustavo, Valentini, José Ernesto, Quaranta, Nancy Esther, and Soon, Willie W. -H. 2018. "Lunar fingerprints in the modulated incoming solar radiation: In situ insolation and latitudinal insolation gradients as two important interpretative metrics for paleoclimatic data records and theoretical climate modeling." New Astronomy 58:96– 106. https://doi.org/10.1016/j.newast.2017.08.003
ID: 145736
Type: article
Authors: Cionco, Rodolfo Gustavo; Valentini, José Ernesto; Quaranta, Nancy Esther; Soon, Willie W. -H
Abstract: We present a new set of solar radiation forcing that now incorporated not only the gravitational perturbation of the Sun-Earth-Moon geometrical orbits but also the intrinsic solar magnetic modulation of the total solar irradiance (TSI). This new dataset, covering the past 2000 years as well as a forward projection for about 100 years based on recent result by Velasco-Herrera et al. (2015), should provide a realistic basis to examine and evaluate the role of external solar forcing on Earth climate on decadal, multidecadal to multicentennial timescales. A second goal of this paper is to propose both in situ insolation forcing variable and the latitudinal insolation gradients (LIG) as two key metrics that are subjected to a deterministic modulation by lunar nodal cycle which are often confused with tidal forcing impacts as assumed and interpreted in previous studies of instrumental and paleoclimatic records. Our new results and datasets are made publicly available for all at PANGAEA site.
The quasi-biennial oscillation of 1.7 years in ground level enhancement eventsVelasco Herrera, V. M.Pérez-Peraza, JorgeSoon, WillieMárquez-Adame, J. C.DOI: info:10.1016/j.newast.2017.09.007v. 607–13
Velasco Herrera, V. M., Pérez-Peraza, Jorge, Soon, Willie, and Márquez-Adame, J. C. 2018. "The quasi-biennial oscillation of 1.7 years in ground level enhancement events." New Astronomy 60:7– 13. https://doi.org/10.1016/j.newast.2017.09.007
ID: 147041
Type: article
Authors: Velasco Herrera, V. M.; Pérez-Peraza, Jorge; Soon, Willie; Márquez-Adame, J. C.
Abstract: The so-called Ground Level Enhancement events are sporadic relativistic solar particles measured at ground level by a network of cosmic ray detectors worldwide. These sporadic events are typically assumed to occur by random chance. However, we find that by studying the last 56 ground level enhancement events reported from 1966 through 2014, these events occur preferentially in the positive phase of the quasi-biennial oscillation of 1.7 year periodicity. These discrete ground level enhancement events show that there is another type of solar emission (i.e., wavelike packets) that occurs only in a specific phase of a very particular oscillation. We interpret this empirical result to support that ground level enhancement events are not a result of purely stochastic processes. We used the Morlet wavelet to analyze the phase of each of the periodicities found by the wavelet analyses and local variations of power spectral density in these sporadic events. We found quasi-regular periodicities of 10.4, 6.55, 4.12, 2.9, 1.73, 0.86, 0.61, 0.4 and 0.24 years in ground level enhancements. Although some of these quasi-biennial oscillation periodicities (i.e., oscillations operating between 0.6 and 4 years) may be interpreted as simply harmonics and overtones of the fundamental solar cycle from the underlying sun-spot magnetism phenomenon. The sources of these periodicities are still unclear. Also there is no clear mechanism for the variability of the quasi-biennial oscillation periodicities itself. The quasi-biennial oscillation periodicities are broadly considered to be a variation of solar activity, associated with the solar dynamo process. Also, the intensity of these periodicities is more important around the years of maximum solar activity because the quasi-biennial oscillation periodicities are modulated by the solar cycle where the Sun is more energetically enhanced during activity maxima. To identify the relationships among ground level enhancement, solar, and cosmic rays indices in time-frequency framework, we apply the wavelet coherence analysis. The fingerprints of solar activity and galactic cosmic rays on these phenomena can also be discerned in terms of the prominent quasi-biennial oscillation of about 1.7 years.
The Mount Wilson Observatory S-index of the SunEgeland, RickySoon, WillieBaliunas, SallieHall, Jeffrey C.Pevtsov, Alexei A.Bertello, LucaDOI: info:10.3847/1538-4357/835/1/25v. 83525
Egeland, Ricky, Soon, Willie, Baliunas, Sallie, Hall, Jeffrey C., Pevtsov, Alexei A., and Bertello, Luca. 2017. "The Mount Wilson Observatory S-index of the Sun." The Astrophysical Journal 835:25. https://doi.org/10.3847/1538-4357/835/1/25
ID: 142320
Type: article
Authors: Egeland, Ricky; Soon, Willie; Baliunas, Sallie; Hall, Jeffrey C.; Pevtsov, Alexei A.; Bertello, Luca
Abstract: The most commonly used index of stellar magnetic activity is the instrumental flux scale of singly ionized calcium H & K line core emission, S, developed by the Mount Wilson Observatory (MWO) HK Project, or the derivative index {R}{HK}\prime . Accurately placing the Sun on the S scale is important for comparing solar activity to that of the Sun-like stars. We present previously unpublished measurements of the reflected sunlight from the Moon using the second-generation MWO HK photometer during solar cycle 23 and determine cycle minimum {S}23,\min =0.1634+/- 0.0008, amplitude {{? }}{S}23=0.0143+/- 0.0012, and mean =0.0143+/- 0.0012, and mean 23> =0.1701+/- 0.0005. By establishing a proxy relationship with the closely related National Solar Observatory Sacramento Peak calcium K emission index, itself well correlated with the Kodaikanal Observatory plage index, we extend the MWO S time series to cover cycles 15-24 and find on average > =0.1701+/- 0.0005. By establishing a proxy relationship with the closely related National Solar Observatory Sacramento Peak calcium K emission index, itself well correlated with the Kodaikanal Observatory plage index, we extend the MWO S time series to cover cycles 15-24 and find on average \min > =0.1621+/- 0.0008, > =0.1621+/- 0.0008, {cyc}> =0.0145+/- 0.0012, }> =0.0145+/- 0.0012, {cyc}> =0.1694+/- 0.0005. Our measurements represent an improvement over previous estimates that relied on stellar measurements or solar proxies with non-overlapping time series. We find good agreement from these results with measurements by the Solar-Stellar Spectrograph at Lowell Observatory, an independently calibrated instrument, which gives us additional confidence that we have accurately placed the Sun on the S-index flux scale.
Generalization of the cross-wavelet functionVelasco Herrera, V. M.Soon, WillieVelasco Herrera, G.Traversi, R.Horiuchi, K.DOI: info:10.1016/j.newast.2017.04.012v. 5686–93
Velasco Herrera, V. M., Soon, Willie, Velasco Herrera, G., Traversi, R., and Horiuchi, K. 2017. "Generalization of the cross-wavelet function." New Astronomy 56:86– 93. https://doi.org/10.1016/j.newast.2017.04.012
ID: 144739
Type: article
Authors: Velasco Herrera, V. M.; Soon, Willie; Velasco Herrera, G.; Traversi, R.; Horiuchi, K.
Abstract: We introduce the method of multiple cross-wavelet algorithm, hereafter also as Einstein's cross functions, for the time-frequency study of solar activity records or any astronomical and geophysical time series in general. The main purpose of this algorithm is to allow the simultaneous examination of the time-frequency information contents in n > 2 time series available. Previous cross-wavelet algorithm only permit the study of two time series at a time and was not extended to the generalized n > 2 problems until now. Furthermore, our new work lifted the restriction from the original formulation that are valid only for stationary processes. We applied our new algorithm to several of the solar activity proxies available in order to demonstrate the broad and powerful utility of this technique. We have used solar activity proxy records that are obtained under different geophysical archives and time periods which are, in turn, suitable for studying both the statistical and physical properties for solar variations valid on timescales of multi-century, millennium to several millennia. We focus on documenting the methodology in this paper rather than any elaborate interpretation of the results.
A phenomenological study of the timing of solar activity minima of the last millennium through a physical modeling of the Sun-Planets InteractionCionco, Rodolfo GustavoSoon, WillieDOI: info:10.1016/j.newast.2014.07.001v. 34164–171
Cionco, Rodolfo Gustavo and Soon, Willie. 2015. "A phenomenological study of the timing of solar activity minima of the last millennium through a physical modeling of the Sun-Planets Interaction." New Astronomy 34:164– 171. https://doi.org/10.1016/j.newast.2014.07.001
ID: 134194
Type: article
Authors: Cionco, Rodolfo Gustavo; Soon, Willie
Abstract: We numerically integrate the Sun’s orbital movement around the barycenter of the solar system under the persistent perturbation of the planets from the epoch J2000.0, backward for about one millennium, and forward for another millennium to 3000 AD. Under the Sun-Planets Interaction (SPI) framework and interpretation of Wolff and Patrone (2010), we calculated the corresponding variations of the most important storage of the specific potential energy (PE) within the Sun that could be released by the exchanges between two rotating, fluid-mass elements that conserve its angular momentum. This energy comes about as a result of the roto-translational dynamics of the cell around the solar system barycenter. We find that the maximum variations of this PE storage correspond remarkably well with the occurrences of well-documented Grand Minima (GM) solar events throughout the available proxy solar magnetic activity records for the past 1000 yr. It is also clear that the maximum changes in PE precede the GM events in that we can identify precursor warnings to the imminent weakening of solar activity for an extended period. The dynamical explanation of these PE minima is connected to the minima of the Sun’s position relative to the barycenter as well as the significant amount of time the Sun’s inertial motion revolving near and close to the barycenter. We presented our calculation of PE forward by another 1000 yr until 3000 AD. If the assumption of the solar activity minima corresponding to PE minima is correct, then we can identify quite a few significant future solar activity GM events with a clustering of PE minima pulses starting at around 2150 AD, 2310 AD, 2500 AD, 2700 AD and 2850 AD.
Indian summer monsoon rainfall: Dancing with the tunes of the sunHiremath, K. M.Manjunath, HegdeSoon, WillieDOI: info:10.1016/j.newast.2014.08.002v. 358–19
Hiremath, K. M., Manjunath, Hegde, and Soon, Willie. 2015. "Indian summer monsoon rainfall: Dancing with the tunes of the sun." New Astronomy 35:8– 19. https://doi.org/10.1016/j.newast.2014.08.002
ID: 135158
Type: article
Authors: Hiremath, K. M.; Manjunath, Hegde; Soon, Willie
Abstract: There is strong statistical evidence that solar activity influences the Indian summer monsoon rainfall. To search for a physical link between the two, we consider the coupled cloud hydrodynamic equations, and derive an equation for the rate of precipitation that is similar to the equation of a forced harmonic oscillator, with cloud and rain water mixing ratios as forcing variables. Those internal forcing variables are parameterized in terms of the combined effect of external forcing as measured by sunspot and coronal hole activities with several well known solar periods (9, 13 and 27 days; 1.3, 5, 11 and 22 years). The equation is then numerically solved and the results show that the variability of the simulated rate of precipitation captures very well the actual variability of the Indian monsoon rainfall, yielding vital clues for a physical understanding that has so far eluded analyses based on statistical correlations alone. We also solved the precipitation equation by allowing for the effects of long-term variation of aerosols. We tentatively conclude that the net effects of aerosols variation are small, when compared to the solar factors, in terms of explaining the observed rainfall variability covering the full Indian monsoonal geographical domains.
Climate Consensus and `Misinformation': A Rejoinder to Agnotology, Scientific Consensus, and the Teaching and Learning of Climate ChangeLegates, David R.Soon, WillieBriggs, William M.Monckton of Brenchley, ChristopherDOI: info:10.1007/s11191-013-9647-9v. 24299–318
Legates, David R., Soon, Willie, Briggs, William M., and Monckton of Brenchley, Christopher. 2015. "Climate Consensus and `Misinformation': A Rejoinder to Agnotology, Scientific Consensus, and the Teaching and Learning of Climate Change." Science & Education 24:299– 318. https://doi.org/10.1007/s11191-013-9647-9
ID: 135984
Type: article
Authors: Legates, David R.; Soon, Willie; Briggs, William M.; Monckton of Brenchley, Christopher
Abstract: Agnotology is the study of how ignorance arises via circulation of misinformation calculated to mislead. Legates et al. (Sci Educ 22:2007-2017, 2013) had questioned the applicability of agnotology to politically-charged debates. In their reply, Bedford and Cook (Sci Educ 22:2019-2030, 2013), seeking to apply agnotology to climate science, asserted that fossil-fuel interests had promoted doubt about a climate consensus. Their definition of climate `misinformation' was contingent upon the post-modernist assumptions that scientific truth is discernible by measuring a consensus among experts, and that a near unanimous consensus exists. However, inspection of a claim by Cook et al. (Environ Res Lett 8:024024, 2013) of 97.1 % consensus, heavily relied upon by Bedford and Cook, shows just 0.3 % endorsement of the standard definition of consensus: that most warming since 1950 is anthropogenic. Agnotology, then, is a two-edged sword since either side in a debate may claim that general ignorance arises from misinformation allegedly circulated by the other. Significant questions about anthropogenic influences on climate remain. Therefore, Legates et al. appropriately asserted that partisan presentations of controversies stifle debate and have no place in education.
Response to the comment on: “Soon, W., and Legates, D.R., 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, (2013) 45-56” by F. Meunier and A. H. ReisSoon, WillieLegates, David R.DOI: info:10.1016/j.jastp.2015.01.013v. 12892–93
Soon, Willie and Legates, David R. 2015. "Response to the comment on: “Soon, W., and Legates, D.R., 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, (2013) 45-56” by F. Meunier and A. H. Reis." Journal of Atmospheric and Solar-Terrestrial Physics 128:92– 93. https://doi.org/10.1016/j.jastp.2015.01.013
ID: 136554
Type: article
Authors: Soon, Willie; Legates, David R.
Abstract: We thank Meunier and Reis (hereafter as MR) for their comments on our paper. We, however, do not see the relevance of their alternative interpretation to our original results and believe this reflects their confusion regarding our conclusions rather than a discussion on physical mechanisms. In the context of this quote, note that even Pallé et al. (2009:3)admitted that “while the deseasonalized CERES data has a small year to year variability (Fig. 2 of Pallé et al., 2009), the Earthshine data seem to present overly large interannual anomalies, along with a large size of the error bars associated to the yearly means [which] is mostly due to sampling issues, as Earthshine measurements are taken from a single station.”To put this in a different way, the relatively short duration of Earthshine or satellite-borne measurements of global albedo is unable to provide the necessary information on how this important quantity may vary on multi-decadal timescales as studies by Soon and Legates (2013). We note that efforts to 'reconstruct' Earth albedo over a 120-to-130 year period have been discussed by Zavalishin (2014) but we stress that such research requires non-independent information regarding surface temperatures and some unproven assumptions about the thermal inertia of the hydrosphere.<ce:bibliography
The Maunder minimum (1645-1715) was indeed a grand minimum: A reassessment of multiple datasetsUsoskin, Ilya G.Arlt, RainerAsvestari, EleannaHawkins, EdKäpylä, MaaritKovaltsov, Gennady A.Krivova, NatalieLockwood, MichaelMursula, KaleviO'Reilly, JezebelOwens, MatthewScott, Chris J.Sokoloff, Dmitry D.Solanki, Sami K.Soon, WillieVaquero, José M.DOI: info:10.1051/0004-6361/201526652v. 581A95
Usoskin, Ilya G., Arlt, Rainer, Asvestari, Eleanna, Hawkins, Ed, Käpylä, Maarit, Kovaltsov, Gennady A., Krivova, Natalie, Lockwood, Michael, Mursula, Kalevi, O'Reilly, Jezebel, Owens, Matthew, Scott, Chris J., Sokoloff, Dmitry D., Solanki, Sami K., Soon, Willie, and Vaquero, José M. 2015. "The Maunder minimum (1645-1715) was indeed a grand minimum: A reassessment of multiple datasets." Astronomy and Astrophysics 581:A95. https://doi.org/10.1051/0004-6361/201526652
ID: 140503
Type: article
Authors: Usoskin, Ilya G.; Arlt, Rainer; Asvestari, Eleanna; Hawkins, Ed; Käpylä, Maarit; Kovaltsov, Gennady A.; Krivova, Natalie; Lockwood, Michael; Mursula, Kalevi; O'Reilly, Jezebel; Owens, Matthew; Scott, Chris J.; Sokoloff, Dmitry D.; Solanki, Sami K.; Soon, Willie; Vaquero, José M.
Abstract:
Aims: Although the time of the Maunder minimum (1645-1715) is widely known as a period of extremely low solar activity, it is still being debated whether solar activity during that period might have been moderate or even higher than the current solar cycle #24. We have revisited all existing evidence and datasets, both direct and indirect, to assess the level of solar activity during the Maunder minimum.
Methods: We discuss the East Asian naked-eye sunspot observations, the telescopic solar observations, the fraction of sunspot active days, the latitudinal extent of sunspot positions, auroral sightings at high latitudes, cosmogenic radionuclide data as well as solar eclipse observations for that period. We also consider peculiar features of the Sun (very strong hemispheric asymmetry of the sunspot location, unusual differential rotation and the lack of the K-corona) that imply a special mode of solar activity during the Maunder minimum.
Results: The level of solar activity during the Maunder minimum is reassessed on the basis of all available datasets.
Conclusions: We conclude that solar activity was indeed at an exceptionally low level during the Maunder minimum. Although the exact level is still unclear, it was definitely lower than during the Dalton minimum of around 1800 and significantly below that of the current solar cycle #24. Claims of a moderate-to-high level of solar activity during the Maunder minimum are rejected with a high confidence level.
Learning and Teaching Climate Science: The Perils of Consensus Knowledge Using AgnotologyLegates, David R.Soon, WillieBriggs, William M.DOI: info:10.1007/s11191-013-9588-3v. 222007–2017
Legates, David R., Soon, Willie, and Briggs, William M. 2013. "Learning and Teaching Climate Science: The Perils of Consensus Knowledge Using Agnotology." Science & Education 22:2007– 2017. https://doi.org/10.1007/s11191-013-9588-3
ID: 116789
Type: article
Authors: Legates, David R.; Soon, Willie; Briggs, William M.
Abstract: Agnotology has been defined in a variety of ways including "the study of ignorance and its cultural production" and "the study of how and why ignorance or misunderstanding exists." More recently, however, it has been posited that agnotology should be used in the teaching of climate change science. But rather than use agnotology to enhance an understanding of the complicated nature of the complex Earth's climate, the particular aim is to dispel alternative viewpoints to the so-called consensus science. One-sided presentations of controversial topics have little place in the classroom as they serve only to stifle debate and do not further knowledge and enhance critical thinking. Students must understand not just what is known and why it is known to be true but also what remains unknown and where the limitations on scientific understanding lie. Fact recitation coupled with demonizing any position or person who disagrees with a singularly-derived conclusion has no place in education. Instead, all sides must be covered in highly debatable and important topics such as climate change, because authoritarian science never will have all the answers to such complex problems.
General conclusions regarding the planetary-solar-terrestrial interactionMörner, N. -ATattersall, R.Solheim, J. -ECharvatova, I.Scafetta, N.Jelbring, H.Wilson, I. R.Salvador, R.Willson, R. C.Hejda, P.Soon, WillieVelasco Herrera, V. M.Humlum, O.Archibald, D.Yndestad, H.Easterbrook, D.Casey, J.Gregori, G.Henriksson, G.DOI: info:10.5194/prp-1-205-2013v. 1205–206
Mörner, N. -A, Tattersall, R., Solheim, J. -E, Charvatova, I., Scafetta, N., Jelbring, H., Wilson, I. R., Salvador, R., Willson, R. C., Hejda, P., Soon, Willie, Velasco Herrera, V. M., Humlum, O., Archibald, D., Yndestad, H., Easterbrook, D., Casey, J., Gregori, G., and Henriksson, G. 2013. "General conclusions regarding the planetary-solar-terrestrial interaction." Pattern Recognition in Physics 1:205– 206. https://doi.org/10.5194/prp-1-205-2013
ID: 118364
Type: article
Authors: Mörner, N. -A; Tattersall, R.; Solheim, J. -E; Charvatova, I.; Scafetta, N.; Jelbring, H.; Wilson, I. R.; Salvador, R.; Willson, R. C.; Hejda, P.; Soon, Willie; Velasco Herrera, V. M.; Humlum, O.; Archibald, D.; Yndestad, H.; Easterbrook, D.; Casey, J.; Gregori, G.; Henriksson, G.
Abstract: In a collection of research papers devoted to the problem of solar variability and its origin in planetary beat, it is demonstrated that the forcing function originates from gravitational and inertial effects on the Sun from the planets and their satellites. This conclusion is shared by nineteen co-authors.
Solar irradiance modulation of Equator-to-Pole (Arctic) temperature gradients: Empirical evidence for climate variation on multi-decadal timescalesSoon, WillieLegates, David R.DOI: info:10.1016/j.jastp.2012.11.015v. 9345–56
Soon, Willie and Legates, David R. 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. https://doi.org/10.1016/j.jastp.2012.11.015
ID: 114772
Type: article
Authors: Soon, Willie; Legates, David R.
Abstract: Using thermometer-based air temperature records for the period 1850-2010, we present empirical evidence for a direct relationship between total solar irradiance (TSI) and the Equator-to-Pole (Arctic) surface temperature gradient (EPTG). Modulation of the EPTG by TSI is also shown to exist, in variable ways, for each of the four seasons. Interpretation of the positive relationship between the TSI and EPTG indices suggests that solar-forced changes in the EPTG may represent a hemispheric-scale relaxation response of the system to a reduced Equator-to-Pole temperature gradient, which occurs in response to an increasing gradient of incoming solar insolation. Physical bases for the TSI-EPTG relationship are discussed with respect to their connections with large-scale climate dynamics, especially a critical relationship with the total meridional poleward energy transport. Overall, evidence suggests that a net increase in the TSI, or in the projected solar insolation gradient which reflects any net increase in solar radiation, has caused an increase in both oceanic and atmospheric heat transport to the Arctic in the warm period since the 1970s, resulting in a reduced temperature gradient between the Equator and the Arctic. We suggest that this new interpretative framework, which involves the extrinsic modulation of the total meridional energy flux beyond the implicit assumptions of the Bjerknes Compensation rule, may lead to a better understanding of how global and regional climate has varied through the Holocene and even the Quaternary (the most recent 2.6 million years of Earth's history). Similarly, a reassessment is now required of the underlying mechanisms that may have governed the equable climate dynamics of the Eocene (35-55 million years ago) and late Cretaceous (65-100 million years ago), both of which were warm geological epochs. This newly discovered relationship between TSI and the EPTG represents the "missing link" that was implicit in the empirical relationship that Soon (2009) recently demonstrated to exist between multi-decadal TSI and Arctic and North Atlantic climatic change.
Temporal derivative of Total Solar Irradiance and anomalous Indian summer monsoon: An empirical evidence for a Sun–climate connectionAgnihotri, RajeshDutta, KoushikSoon, WillieDOI: info:10.1016/j.jastp.2011.06.006v. 73No. 131980–1987
Agnihotri, Rajesh, Dutta, Koushik, and Soon, Willie. 2011. "Temporal derivative of Total Solar Irradiance and anomalous Indian summer monsoon: An empirical evidence for a Sun–climate connection." Journal of Atmospheric and Solar-Terrestrial Physics 73 (13):1980– 1987. https://doi.org/10.1016/j.jastp.2011.06.006
ID: 102305
Type: article
Authors: Agnihotri, Rajesh; Dutta, Koushik; Soon, Willie
Abstract: Identifying the pattern of natural climate variability is of immense importance to delineate the effects of anthropogenic climate changes. Global and regional climates are suspected to vary, in unison or with delays, with the Total Solar Irradiance (TSI) at decadal to centennial timescales. Here we show that the Indian summer monsoon rainfall correlates well with the temporal derivative of TSI on multi-decadal timescales. This linkage between the temporal derivative of TSI and the Indian summer monsoon is tested and corroborated both for the instrumental period (1871–2006) and for the last ˜300 years using a speleothem ?18O record representing rainfall in southwestern India. Our analyses indicate that anomalous dry periods of the Indian monsoon are mostly coincident with negative TSI derivative. This study thus demonstrates the potential of 'TSI derivative' as an important indicator of natural monsoon variability on an interdecadal timescale.