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Journal articles on the topic 'Equinoxes'
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Xie, Shang-Ping. "Unequal equinoxes." Nature 500, no. 7460 (July 24, 2013): 33–34. http://dx.doi.org/10.1038/nature12456.
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Pathak, K. N., R. D. Jivrajani, H. P. Joshi, and K. N. Iyer. "Characteristics of VHF scintillations in the equatorial anomaly crest region in India." Annales Geophysicae 13, no. 7 (July 31, 1995): 730–39. http://dx.doi.org/10.1007/s00585-995-0730-7.
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Abstract. The characteristics of ionospheric scintillations at Rajkot in the equatorial anomaly crest region in India are described for the years 1987–1991 by monitoring the 244-MHz transmission from the satellite FLEETSAT. This period covers the ascending phase of solar cycle 22. Scintillations occur predominantly in the pre-midnight period during equinoxes and winter seasons and in the post-midnight period during summer season. During equinoxes and winter, scintillation occurrence increases with solar activity, whilst in summer it is found to decrease with solar activity. Statistically, scintillation occurrence is suppressed by magnetic activity. The characteristics observed during winter and equinoxes are similar to those seen at the equatorial station, Trivandrum. This, coupled with the nature of the post-sunset equatorial F-region drift and h'F variations, supports the view that at the anomaly crest station, scintillations are of equatorial origin during equinox and winter, whilst in summer they may be of mid-latitude type. The variations in scintillation intensity (in dB) with season and solar activity are also reported.
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Ogwala, Aghogho, Emmanuel Olufemi Somoye, Olugbenga Ogunmodimu, Rasaq Adewemimo Adeniji-Adele, Eugene Oghenakpobor Onori, and Oluwole Oyedokun. "Diurnal, seasonal and solar cycle variation in total electron content and comparison with IRI-2016 model at Birnin Kebbi." Annales Geophysicae 37, no. 5 (September 5, 2019): 775–89. http://dx.doi.org/10.5194/angeo-37-775-2019.
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Abstract. The ionosphere is the major error source for the signals of global positioning system (GPS) satellites. In the analysis of GPS measurements, ionospheric error is assumed to be somewhat of a nuisance. The error induced by the ionosphere is proportional to the number of electrons along the line of sight (LOS) from the satellite to receiver and can be determined in order to study the diurnal, seasonal, solar cycle and spatial variations in the ionosphere during quiet and disturbed conditions. In this study, we characterize the diurnal, seasonal and solar cycle variation in observed total electron content (OBS-TEC) and compare the results with the International Reference Ionosphere (IRI-2016) model. We obtained TEC from a dual-frequency GPS receiver located at Birnin Kebbi Federal Polytechnic (BKFP) in northern Nigeria (geographic location: 12.64∘ N, 4.22∘ E; 2.68∘ N dip) for the period 2011–2014. We observed differences between the diurnal variation in OBS-TEC and the IRI-2016 model for all hours of the day except during the post-midnight hours. Slight post-noon peaks in the daytime maximum and post-sunset decrease and enhancement are observed in the diurnal variation in OBS-TEC during the equinoxes. On a seasonal scale, we observed that OBS-TEC values were higher in the equinoxes than the solstices only in 2012. However, in 2011, the September equinox and December solstice recorded a higher magnitude, followed by the March equinox, and the magnitude was lowest in the June solstice. In 2013, the December solstice magnitude was highest, followed by the equinoxes, and it was lowest in the June solstice. In 2014, the March equinox and December solstice magnitudes were higher than the September equinox and June solstice magnitude. The June solstice consistently recorded the lowest values for all the years. OBS-TEC is found to increase from 2011 to 2014, thus revealing solar cycle dependence.
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Venkateswara Rao, N., T. Tsuda, and Y. Kawatani. "A remarkable correlation between short period gravity waves and semiannual oscillation of the zonal wind in the equatorial mesopause region." Annales Geophysicae 30, no. 4 (April 19, 2012): 703–10. http://dx.doi.org/10.5194/angeo-30-703-2012.
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Abstract. The variability of zonal winds and the horizontal wind velocity variance of short period (20–120 min) gravity waves (GWs) in the equatorial mesopause region are studied using medium frequency (MF) radar observations from Pameungpeuk (7.4° S, 107.4° E) during 2004–2010. The zonal winds display a distinct semiannual oscillation (called mesospheric semiannual oscillation, MSAO), with westward winds during equinoxes and eastward winds during solstices. Furthermore, the westward winds during March equinox are larger during 2008 and 2009. The short period GW variance also shows a semiannual oscillation with enhanced activity during equinoxes. A good correlation is observed between the zonal winds and the short period GW variance from 2008–2010, with the winds being westward during the times of enhanced GW activity. Such a correlation, however, is less obvious during 2004–2006. The long period (10–20 h) GW variance, on the other hand, does not show such a correlation throughout the observation period.
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Thurston, Hugh. "Early Greek Solstices and Equinoxes." Journal for the History of Astronomy 32, no. 2 (May 2001): 154–56. http://dx.doi.org/10.1177/002182860103200208.
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Eyelade, Victor Adetayo, Adekola Olajide Adewale, Andrew Ovie Akala, Olawale Segun Bolaji, and A. Babatunde Rabiu. "Studying the variability in the diurnal and seasonal variations in GPS total electron content over Nigeria." Annales Geophysicae 35, no. 3 (June 6, 2017): 701–10. http://dx.doi.org/10.5194/angeo-35-701-2017.
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Abstract. The study of diurnal and seasonal variations in total electron content (TEC) over Nigeria has been prompted by the recent increase in the number of GPS continuously operating reference stations (CORSs) across Nigeria as well as the reduced costs of microcomputing. The GPS data engaged in this study were recorded in the year 2012 at nine stations in Nigeria located between geomagnetic latitudes – 4.33 and 0.72° N. The GPS data were used to derive GPS TEC, which was analysed for diurnal and seasonal variations. The results obtained were used to produce local GPS TEC maps and bar charts. The derived GPS TEC across all the stations demonstrates consistent minimum diurnal variations during the pre-sunrise hours 04:00 to 06:00 LT, increases with sharp gradient during the sunrise period (∼ 07:00 to 09:00 LT), attains postnoon maximum at about 14:00 LT, and then falls to a minimum just before sunset. Generally, daytime variations are found to be greater than nighttime variations, which range between 0 and 5 TECU. The seasonal variation depicts a semi-annual distribution with higher values (∼ 25–30 TECU) around equinoxes and lower values (∼ 20–25 TECU) around solstices. The December Solstice magnitude is slightly higher than the June Solstice magnitude at all stations, while March Equinox magnitude is also slightly higher than September Equinox magnitude at all stations. Thus, the seasonal variation shows an asymmetry in equinoxes and solstices, with the month of October displaying the highest values of GPS TEC across the latitudes.
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Wang, G. J., J. K. Shi, X. Wang, S. P. Shang, G. Zherebtsov, and O. M. Pirog. "The statistical properties of spread F observed at Hainan station during the declining period of the 23rd solar cycle." Annales Geophysicae 28, no. 6 (June 10, 2010): 1263–71. http://dx.doi.org/10.5194/angeo-28-1263-2010.
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Abstract. The temporal variations of the low latitude nighttime spread F (SF) observed by DPS-4 digisonde at low latitude Hainan station (geog. 19.5° N, 109.1° E, dip lat. 9.5° N) during the declining solar cycle 23 from March 2002 to February 2008 are studied. The spread F measured by the digisonde were classified into four types, i.e., frequency SF (FSF), range SF (RSF), mixed SF (MSF), and strong range SF (SSF). The statistical results show that MSF and SSF are the outstanding irregularities in Hainan, MSF mainly occurs during summer and low solar activity years, whereas SSF mainly occurs during equinoxes and high solar activity years. The SSF has a diurnal peak before midnight and usually appears during 20:00–02:00 LT, whereas MSF peaks nearly or after midnight and occurs during 22:00–06:00 LT. The time of maximum occurrence of SSF is later in summer than in equinoxes and this time delay can be caused by the later reversal time of the E×B drift in summer. The SunSpot Number (SSN) dependence of each type SF is different during different season. The FSF is independent of SSN during each season; RSF with SSN is positive relation during equinoxes and summer and is no relationship during the winter; MSF is significant dependence on SSN during the summer and winter, and does not relate to SSN during the equinoxes; SSF is clearly increasing with SSN during equinoxes and summer, while it is independent of SSN during the winter. The occurrence numbers of each type SF and total SF have the same trend, i.e., increasing as Kp increases from 0 to 1, and then decreasing as increasing Kp. The correlation with Kp is negative for RSF, MSF, SSF and total SF, but is vague for the FSF.
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Ashkenazy, Yosef, Ian Eisenman, Hezi Gildor, and Eli Tziperman. "The Effect of Milankovitch Variations in Insolation on Equatorial Seasonality." Journal of Climate 23, no. 23 (December 1, 2010): 6133–42. http://dx.doi.org/10.1175/2010jcli3700.1.
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Abstract Although the sun crosses the equator 2 times per year at the equinoxes, at times in the past the equatorial insolation has had only one maximum and one minimum throughout the seasonal cycle because of Milankovitch orbital variations. Here a state-of-the-art coupled atmosphere–ocean general circulation model is used to study the effect of such insolation forcing on equatorial surface properties, including air and sea temperature, salinity, winds, and currents. It is shown that the equatorial seasonality is altered according to the insolation with, for example, either maximum sea surface temperature (SST) close to the vernal equinox and minimum SST close to the autumnal equinox or vice versa. The results may have important implications for understanding tropical climate as well as for the interpretation of proxy data collected from equatorial regions.
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Corre, Jean-François. "Le problème des équinoxes dans l’astronomie grecque." Phronesis 60, no. 4 (September 11, 2015): 351–79. http://dx.doi.org/10.1163/15685284-12341289.
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When were equinoxes first understood? If the notion were as simple as it might seem, it ought not to be difficult to determine; but the controversies around it show that the matter is not so simple. In fact, it is very difficult to establish the equinoxes, and that difficulty led to several revisions of the notion. But with them came a change to the object under discussion changed as well – more profound than one would think given the stability of the term. This article traces the story.
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Jiang, G., J. Xu, and S. J. Franke. "The 8-h tide in the mesosphere and lower thermosphere over Maui (20.75° N, 156.43° W)." Annales Geophysicae 27, no. 5 (May 4, 2009): 1989–99. http://dx.doi.org/10.5194/angeo-27-1989-2009.
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Abstract. Wind data collected by the Maui meteor radar (20.75° N, 156.43° W) are used to study the 8-h tide in the mesosphere and lower thermosphere (MLT) region at a low-latitude station. The data set spans the time interval from 19 May 2002 to 24 May 2007. Our results show that the 8-h tide is a regular and distinct feature over Maui. The meridional component of this wave is significantly larger than the zonal component. The meridional component exhibits a semiannual variation in amplitude, with peaks near the equinoxes, whereas the variation of the zonal component does not show this seasonal characteristic. The strongest wave motions mostly occur in the height range of 92–96 km near spring equinox (March) and at higher altitudes near autumn equinox (October). The vertical variations of 8-h tidal phase at Maui indicate an upward wave energy flux. The vertical wavelengths are ≥54 km in equinox months.
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Liu, Libo, Maosheng He, Xin'an Yue, Baiqi Ning, and Weixing Wan. "Ionosphere around equinoxes during low solar activity." Journal of Geophysical Research: Space Physics 115, A9 (September 2010): n/a. http://dx.doi.org/10.1029/2010ja015318.
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Mielich, J., and J. Bremer. "A modified index for the description of the ionospheric short- and long-term activity." Annales Geophysicae 28, no. 12 (December 21, 2010): 2227–36. http://dx.doi.org/10.5194/angeo-28-2227-2010.
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Abstract. A modified ionospheric activity index AI has been developed on the basis of ionospheric foF2 observations. Such index can be helpful for an interested user to get information about the current state of the ionosphere. Using ionosonde data of the station Juliusruh (54.6° N; 13.4° E) this index has been tested for the time interval from January 1996 until December 2008. This index has no diurnal and seasonal variations, only a small positive dependence on the solar activity could be found. The variability of this index has, however, a marked seasonal variability with maxima during the equinoxes, a clear minimum in summer, and enhanced values in winter. The observed variability of AI is strongly correlated with the geomagnetic activity, most markedly during the equinoxes, whereas the influence of the solar activity is markedly smaller and mostly insignificant. Strong geomagnetic disturbances cause in middle latitudes in general negative disturbances in AI, mostly pronounced during equinoxes and summer and only partly during winter, thus in agreement with the current physical knowledge about ionospheric storms.
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Zhang, H., Y. Liu, J. Wu, T. Xu, and D. Sheng. "Observations and modeling of UHF-band scintillation occurrence probability over the low-latitude region of China during the maximum activity of solar cycle 24." Annales Geophysicae 33, no. 1 (January 16, 2015): 93–100. http://dx.doi.org/10.5194/angeo-33-93-2015.
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Abstract. The climatological characteristics of UHF-band scintillations over the low-latitude region of China were investigated by analyzing the observations recorded at three stations of our regional network of satellite-beacon-based scintillation monitoring in 2013. The three stations are Hainan (geographic 20.0° N, 110.3° E; geomagnetic 10.1° N, 177.4° W, dip 28.2°), Guangzhou (geographic 23.0° N, 113.0° E; geomagnetic 13.1° N, 174.8° W, dip 33.9°) and Kunming (geographic 25.6° N, 103.7° E; geomagnetic 15.7° N, 176.4° E, dip 39.0°), located at low latitudes of China. The variations of UHF-band scintillation occurrence with latitude, time and season are presented in detail to understand the morphology and climatology of ionospheric scintillations over the low-latitude region of China. An equinoctial asymmetry in the occurrences of scintillation and an obvious difference of the onset time of scintillations between Hainan and Kunming is noted in this data set. Subsequently, the ionosonde data are utilized to study the possible causes of the asymmetry between two equinoxes. The observations suggest that the mean critical frequency (foF2) at 20:00 LT (12:00 UT) in the autumnal equinoctial months (September and October) and the vernal equinoctial months (March and April) has a similar asymmetry. The ratio of the mean foF2 between two equinoxes is proportional to the ratio between the maximum scintillation occurrence in the autumnal equinox and in the vernal equinox. Therefore, this ratio can act as a proxy for the equinoctial asymmetry in the occurrences of scintillation over the low-latitude region of China, and can be used to model the equinoctial asymmetry in our empirical climatological model of scintillation occurrence probability (CMSOP). The CMSOP can provide the predictions of the occurrences of scintillation over the low-latitude region of China and was validated in this study.
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Tang, Long, Wu Chen, Osei-Poku Louis, and Mingli Chen. "Study on Seasonal Variations of Plasma Bubble Occurrence over Hong Kong Area Using GNSS Observations." Remote Sensing 12, no. 15 (July 28, 2020): 2423. http://dx.doi.org/10.3390/rs12152423.
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In this study, the characteristics and causes of the seasonal variations in plasma bubble occurrence over the Hong Kong area were investigated using the local Global Navigation Satellite System (GNSS) network. Generally, the occurrences of plasma bubbles were larger in the two equinoxes than in the two solstices. Furthermore, two seasonal asymmetries in plasma bubble occurrence were observed: plasma bubble activity was more frequent in the spring equinox than in the autumn equinox (equinoctial asymmetry), and more frequent in the summer solstice than in the winter solstice (solstitial asymmetry). The equinoctial asymmetry could be explained using the Rayleigh–Taylor (R–T) instability mechanism, due to larger R–T growth rates in the spring equinox than in the autumn equinox. However, the R–T growth rate was smaller in the summer solstice than in the winter solstice, suggesting the R–T instability mechanism was inapplicable to the solstitial asymmetry. Our results showed there were more zonally propagating atmospheric gravity waves (GWs) induced by thunderstorm events over the Hong Kong area in the summer solstice than the winter solstice. So, the solstitial asymmetry could be attributed to the seeding mechanism of thunderstorm-driven atmospheric GWs.
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Voiculescu, Mirela, and Tuomo Nygrén. "IMF effect on ionospheric trough occurrence at equinoxes." Advances in Space Research 40, no. 12 (January 2007): 1935–40. http://dx.doi.org/10.1016/j.asr.2007.04.108.
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Sivla, W. T., and H. McCreadie. "Mid-latitude thermospheric zonal winds during the equinoxes." Advances in Space Research 54, no. 3 (August 2014): 499–508. http://dx.doi.org/10.1016/j.asr.2014.03.014.
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Kanekal, S. G., D. N. Baker, and R. L. McPherron. "On the seasonal dependence of relativistic electron fluxes." Annales Geophysicae 28, no. 5 (May 10, 2010): 1101–6. http://dx.doi.org/10.5194/angeo-28-1101-2010.
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Abstract. The nature of the seasonal dependence of relativistic electron fluxes in the Earth's outer zone is investigated using 11 years of data from sensors onboard the SAMPEX spacecraft. It is found that, the relativistic electron fluxes show a strong semiannual modulation. However, the highest electron fluxes occur at times well away from the nominal equinoxes, lagging them by about 30 days. The time lag also shows a solar cycle phase dependence for the peak fluxes. The electron peak fluxes lag the vernal equinox by almost 60 days during the ascending phase of the solar cycle while the time lag near the autumnal equinox remains unchanged. The observed times of the peak electron fluxes during the descending phase of the solar cycle agrees most closely with the Russel-Mcpherron effect and less so with the equinoctial effect even after including propagation effects for finite solar wind speed. The observed times of the electron peaks are in disagreement with the axial effect. The asymmetrical response of the relativistic electrons during the ascending part of the solar cycle remains a puzzle.
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Rodríguez Arribas, Josefina. "Significance of the Equinoxes in Abraham Ibn Ezra's Cosmology." Helmántica, no. 175 (January 1, 2007): 115–40. http://dx.doi.org/10.36576/summa.29395.
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Gontier, A. M., and N. Capitaine. "High-accuracy equation of equinoxes and VLBI astrometric Modelling." International Astronomical Union Colloquium 131 (1991): 342–45. http://dx.doi.org/10.1017/s0252921100013609.
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AbstractIn the course of implementing the use of nonrotating origin (Guinot 1979) in astrometric VLBI, for the transformation between celestial and terrestrial frames, we have compared the new approach with the classical one. We have shown that a difference exists between the two procedures at a few milliarcsecond level; this difference is due to the terms generally neglected when considering the equation of equinoxes in the classical representation of the Earth angle of rotation.
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Capitaine, N., and A. M. Gontier. "Procedure for VLBI Estimates of Earth Rotation Parameters Referred to the Nonrotating Origin." International Astronomical Union Colloquium 127 (1991): 77–84. http://dx.doi.org/10.1017/s0252921100063594.
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AbstractThis paper investigates the practical use of the nonrotating origin (NRO) (Guinot 1979) for estimating the Earth Rotation Parameters from VLBI data, which is based on the rotational transformation between the geocentric celestial and terrestrial frames as previously derived by Capitaine (1990). Numerical checks of consistency show that the transformation referred to the NRO is equivalent to the classical one referred to the equinox and considering the complete “equation of the equinoxes” (Aoki & Kinoshita 1983). The paper contains the expressions for the partial derivatives of the VLBI geometric delay to be used for the adjustment of the pole coordinates, UT1 and deficiencies in the two celestial coordinates of the Celestial Ephemeris Pole (CEP) in the multiparameters fits to VLBI data. The use of the NRO is shown to simplify the estimates of these parameters and to free the estimated UT1 parameter from the model for precession and nutation.
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Fujimoto, Akiko, Akimasa Yoshikawa, Teiji Uozumi, and Shuji Abe. "Seasonal dependence of semidiurnal equatorial magnetic variation during quiet and disturbed periods." E3S Web of Conferences 127 (2019): 02025. http://dx.doi.org/10.1051/e3sconf/201912702025.
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The analysis of 20-year long-term semidiurnal lunar tidal variations gave the evidence that the semidiurnal variations are completely different between the magnetic quiet and disturbed periods. This is the first time that the seasonal dependence of disturbance-time semidiurnal variation has been provided from the analysis of the EE-index. We found the Kp dependence of semidiurnal variation: For full and new moon phase, counter troughs are amplified during disturbance time, possibly related to disturbance dynamo. For all moon phase, there are positive enhancements in dawn and strong depressions after sunset, resulting from the penetration of polar electric filed. For Seasonal dependence, semidiurnal variations are divided to three seasonal groups, and characterized as deep trough, enhanced crest and weak structure for D-solstice, Equinoxes and J-solstice, respectively. There is no significant longitudinal difference between Ancon and Davao, except for the amplitude of semidiurnal variations. The deep troughs occur during D-solstice and the enhanced crests during Equinoxes, at both Ancon and Davao.
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Bailey, G. J., Y. Z. Su, and K. I. Oyama. "Yearly variations in the low-latitude topside ionosphere." Annales Geophysicae 18, no. 7 (July 31, 2000): 789–98. http://dx.doi.org/10.1007/s00585-000-0789-0.
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Abstract. Observations made by the Hinotori satellite have been analysed to determine the yearly variations of the electron density and electron temperature in the low-latitude topside ionosphere. The observations reveal the existence of an equinoctial asymmetry in the topside electron density at low latitudes, i.e. the density is higher at one equinox than at the other. The asymmetry is hemisphere-dependent with the higher electron density occurring at the March equinox in the Northern Hemisphere and at the September equinox in the Southern Hemisphere. The asymmetry becomes stronger with increasing latitude in both hemispheres. The behaviour of the asymmetry has no significant longitudinal and magnetic activity variations. A mechanism for the equinoctial asymmetry has been investigated using CTIP (coupled thermosphere ionosphere plasmasphere model). The model results reproduce the observed equinoctial asymmetry and suggest that the asymmetry is caused by the north-south imbalance of the thermosphere and ionosphere at the equinoxes due to the slow response of the thermosphere arising from the effects of the global thermospheric circulation. The observations also show that the relationship between the electron density and electron temperature is different for daytime and nighttime. During daytime the yearly variation of the electron temperature has negative correlation with the electron density, except at magnetic latitudes lower than 10°. At night, the correlation is positive.Key words: Ionosphere (equatorial ionosphere; ionosphere-atmosphere interactions; plasma temperature and density)
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Mukhopadhyay, Utpal. "Precession of the equinoxes and its importance in calendar making." Resonance 8, no. 4 (April 2003): 44–56. http://dx.doi.org/10.1007/bf02883532.
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Maruyama, T., S. Saito, M. Kawamura, K. Nozaki, J. Krall, and J. D. Huba. "Equinoctial asymmetry of a low-latitude ionosphere-thermosphere system and equatorial irregularities: evidence for meridional wind control." Annales Geophysicae 27, no. 5 (May 4, 2009): 2027–34. http://dx.doi.org/10.5194/angeo-27-2027-2009.
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Abstract. Nocturnal ionospheric height variations were analyzed along the meridian of 100° E by using ionosonde data. Two ionosondes were installed near the magnetic conjugate points at low latitudes, and the third station was situated near the magnetic equator. Ionospheric virtual heights were scaled every 15 min and vertical E×B drift velocities were inferred from the equatorial station. By incorporating the inferred equatorial vertical drift velocity, ionospheric bottom heights with the absence of wind were modeled for the two low-latitude conjugate stations, and the deviation in heights from the model outputs was used to infer the transequatorial meridional thermospheric winds. The results obtained for the September and March equinoxes of years 2004 and 2005, respectively, were compared, and a significant difference in the meridional wind was found. An oscillation with a period of approximately 7 h of the meridional wind existed in both the equinoxes, but its amplitude was larger in September as compared to that in March. When the equatorial height reached the maximum level due to the evening enhancement of the zonal electric field, the transequatorial meridional wind velocity reached approximately 10 and 40 m/s for the March and September equinoxes, respectively. This asymmetry of the ionosphere-thermosphere system was found to be associated with the previously reported equinoctial asymmetry of equatorial ionospheric irregularities; the probability for equatorial irregularities to occur is higher in March as compared to that in September at the Indian to Western Pacific longitudes. Numerical simulations of plasma bubble developments were conducted by incorporating the transequatorial neutral wind effect, and the results showed that the growth time (e-folding time) of the bubble was halved when the wind velocity changed from 10 to 40 m/s.
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Arnaiz-Villena, Antonio, Marcial Medina, Valentín Ruiz-del-Valle, Adrian Lopez-Nares, Julian Rodriguez-Rodriguez, and Fabio Suarez-Trujillo. "Cart-ruts in Lanzarote (Canary Islands, Spain) volcanoes tops point to Equinoxes, Summer and Winter Solstices." International Journal of Modern Anthropology 2, no. 13 (July 7, 2020): 123–38. http://dx.doi.org/10.4314/ijma.v2i13.4.
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Cart-ruts have been observed in Mediterranean Basin, Eurasia and Africa. They are rock carved stripes and channels which unexpectedly converge and/or bend, not being useful for transportation use because constant parallelism is not kept. Cart-ruts came first to scholars attention in Malta and Gozo Islands where they are abundant and dated at Bronze or Temple Age of this Archipelago. A big conjoint European investment for Cart-ruts study only got a detailed inventory in several Eurasian and African countries. Age and use of Cart-ruts remains non-discovered: it is admitted that different ages and uses may not be the same for different or even same areas. Azores Archipelago Cart-ruts were left out of this study and we have recently described them at Lanzarote (Canary Islands, Spain) volcanoes tops and slopes and suggested that they could have been useful for space and time measurements. In the present study, Lanzarote is studied and Mt. Mina and Mt. Guardilama mountains Cart-ruts azimuths points to Summer and Winter Solstices sunrises respectively as measured from Quesera/”Cheeseboard” of Zonzamas, which is a prehistoric Guanche lunisolar calendar. Mt. Tenezara Cart-ruts azimuth is pointing towards Equinoxes sunrises, as observed from Zonzamas prehistoric calendar. Thus, a use for measure time and space could be a function for some Lanzarote Cart-ruts. We explain these findings in a prehistoric Guanche aborigine culture context probably common to Atlantic megalithic Bronze Age and to all Canary Islands having prehistoric inter-navigation, because all have similar rock Iberian-Guanche inscriptions and other common cultural traits. Sahara Desert abandoning by people also influenced Mediterranean and Atlantic culture. Probability that 3 out of 7 studied volcano Cart-ruts point to Solstices and Equinoxes by chance is close to zero as calculated by factorial probability methods.
Keywords: Latin, Scripts, Canary Islands, Iberian, Guanche, Lanzarote, Fuerteventura, Quesera-Cheeseboard, Pyramids, Berber, Africa, Punic, Roman, Western Sahara, Tunisia, Canaria, Calendar, Etruscan, Basque, Cart-ruts, Usko-Mediterranean, Solstice, Equinox, Zonzamas, HLA, Genetics, Sahara. Atchano, Malta
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Phanikumar, D. V., A. K. Patra, C. V. Devasia, and G. Yellaiah. "Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde." Annales Geophysicae 26, no. 7 (July 9, 2008): 1865–76. http://dx.doi.org/10.5194/angeo-26-1865-2008.
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Abstract. In this paper, we present seasonal variation of E region field-aligned irregularities (FAIs) observed using the Gadanki radar and compare them with the seasonal variation of Es observed from a nearby location SHAR. During daytime, FAIs occur maximum in summer and throughout the day, as compared to other seasons. During nighttime, FAIs occur equally in both summer and winter, and relatively less in equinoxes. Seasonal variations of Es (i.e. ftEs and fbEs) show that the daytime activity is maximum in summer and the nighttime activity is maximum in equinoxes. No relation is found between FAIs occurrence/SNR and ftEs/fbEs. FAIs occurrence, however, is found to be related well with (ftEs−fbEs). This aspect is discussed in the light of the present understanding of the mid-latitude Es-FAIs relationship. The seasonal variations of FAIs observed at Gadanki are compared in detail with those of Piura, which show a significant difference in the daytime observations. The observed difference has been discussed considering the factors governing the generation of FAIs.
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Ni'ma, Ali Hussein. "The Calculation and Analysis of the Total Electron Content Over Different Latitudes and Seasons Using the Numerical Trapezoidal and Simpson Methods." Baghdad Science Journal 16, no. 4(Suppl.) (December 18, 2019): 1043. http://dx.doi.org/10.21123/bsj.2019.16.4(suppl.).1043.
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It has been shown in ionospheric research that calculation of the total electron content (TEC) is an important factor in global navigation system. In this study, TEC calculation was performed over Baghdad city, Iraq, using a combination of two numerical methods called composite Simpson and composite Trapezoidal methods. TEC was calculated using the line integral of the electron density derived from the International reference ionosphere IRI2012 and NeQuick2 models from 70 to 2000 km above the earth surface. The hour of the day and the day number of the year, R12, were chosen as inputs for the calculation techniques to take into account latitudinal, diurnal and seasonal variation of TEC. The results of latitudinal variation of TEC show anomally called equatorial ionization anomally which presents two crests about the geomagnetic equators. The mean absolute percent errors MAPE for two numerical methods using the electron density profiles shown above were 0.0253, 0.02273 and 0.0213, 0.0124 respectively. The results of seasonal variation of TEC show a larger values for spring and autumn equinoxes other than for summer and winter seasons. The MAPE for autumn equinox has the smallest value than for summer, winter seasons and spring equinox. The MAPE for spring equinox equals to 0.01093 and 0.01015 for Simpson and Trapezoidal methods respectively. For autumn, summer and winter, the MAPE equals to 0.005825 and 0.006629 and 0.04682 and 0.0454, 0.01253 and 0.01231 for Simpson and Trapezoidal methods respectively.
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Wendler, Gerd, and Michael Pook. "On the relationship between extra-terrestrial radiation and surface pressure." Antarctic Science 8, no. 3 (September 1996): 303–5. http://dx.doi.org/10.1017/s0954102096000442.
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The surface pressure of an Antarctic station displays two minima, one in spring, the other in autumn. It is believed that these minima are caused by radiative forcing, as the gradient of the extra-terrestrial radiation is largest during the two equinoxes. The best correlation (r = 0.85) was obtained when the pressure lagged the radiation gradient by ten days.
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Duly, T. M., N. P. Chapagain, and J. J. Makela. "Climatology of nighttime medium-scale traveling ionospheric disturbances (MSTIDs) in the Central Pacific and South American sectors." Annales Geophysicae 31, no. 12 (December 20, 2013): 2229–37. http://dx.doi.org/10.5194/angeo-31-2229-2013.
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Abstract. We present occurrence rate statistics for nighttime medium-scale traveling ionospheric disturbances (MSTIDs) in the Central Pacific and South American sectors using data collected by 630.0 nm filtered CCD imaging systems. The data were collected from September 2006 through December 2012. In general, the statistics are in good agreement with the basic linear theory of MSTIDs, with observations coinciding with low F10.7A values, representative of solar minimum. Overall, MSTIDs are observed in approximately 68% of the usable nights near the solstices at mid-latitudes and approximately 20% of the usable nights for equinox periods. Observations closer to the geomagnetic equator yielded a maximum occurrence rate of about 10–20% during the solstices and about 0–3% during the equinoxes. The lower number of MSTID observations near the low latitudes is attributed to limitations of MSTID growth rate, propagation, and/or geometrical observational effects. The relatively large number of MSTID occurrences during the solstices can be accounted for by the neutral wind contribution to the MSTID growth rate either at the local or magnetic conjugate point.
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Деминов, Марат, Marat Deminov, Галина Деминова, Galina Deminova, Виктор Депуев, Viktor Depuev, Анна Депуева, and Anna Depueva. "Dependence of the F2-layer critical frequency median at midlatitudes on geomagnetic activity." Solar-Terrestrial Physics 3, no. 4 (December 29, 2017): 67–73. http://dx.doi.org/10.12737/stp-34201707.
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We put forward a method of separating the geomagnetic activity contribution to the F2-layer critical frequency median, foF2med, at middle latitudes. It is based on the analysis of dfoF2, which is the ratio foF2med/foF2q in percent, where foF2q is the F2-layer critical frequency for quiet conditions. The quantities foF2q and dfoF2 depend on solar and geomagnetic activity respectively. These dependences are taken into account using indices F12 (the average over 12 months flux of solar radiation at 10.7 cm) and Apm (the average over a month value of Ap-index), thus facilitating the use of this method for forecasting foF2med. With this method, from Slough station (51.5° N, 0.6° W) data for midday and midnight for 1954 to 1995 we have found that at midnight the dfoF2 dependence on Apm is significant at the 95 % confidence level for equinoxes and summer. For midday, this dependence is less pronounced and is significant only from April to July. At equinoxes and summer, an Apm increase causes a dfoF2 decrease. For midnight, this feature is more pronounced than for midday. This regularity is valid also for annual average Apm and dfoF2.
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Деминов, Марат, Marat Deminov, Галина Деминова, Galina Deminova, Виктор Депуев, Viktor Depuev, Анна Депуева, and Anna Depueva. "Dependence of the F2-layer critical frequency median at midlatitudes on geomagnetic activity." Solnechno-Zemnaya Fizika 3, no. 4 (December 27, 2017): 74–81. http://dx.doi.org/10.12737/szf-34201707.
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We put forward a method of separating the geomagnetic activity contribution to the F2-layer critical frequency median, foF2med, at middle latitudes. It is based on the analysis of dfoF2, which is the ratio foF2med/foF2q in percent, where foF2q is the F2-layer critical frequency for quiet conditions. The quantities foF2q and dfoF2 depend on solar and geomagnetic activity respectively. These dependences are taken into account using indices F12 (the average over 12 months flux of solar radiation at 10.7 cm) and Apm (the average over a month value of Ap-index), thus facilitating the use of this method for forecasting foF2med. With this method, from Slough station (51.5° N, 0.6° W) data for midday and midnight for 1954 to 1995 we have found that at midnight the dfoF2 dependence on Apm is significant at the 95 % confidence level for equinoxes and summer. For midday, this dependence is less pronounced and is significant only from April to July. At equinoxes and summer, an Apm increase causes a dfoF2 decrease. For midnight, this feature is more pronounced than for midday. This regularity is valid also for annual average Apm and dfoF2.
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Jiang, Yi-Lu, Yuan-Yin Liao, Tzong-Shyan Lin, Ching-Lung Lee, Chung-Ruey Yen, and Wen-Ju Yang. "The Photoperiod-regulated Bud Formation of Red Pitaya (Hylocereus sp.)." HortScience 47, no. 8 (August 2012): 1063–67. http://dx.doi.org/10.21273/hortsci.47.8.1063.
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Red pitaya (Hylocereus sp.), which flowers between May and October and sprouts between November and May in Taiwan, has been confirmed to be a long-day plant. The areoles on the old shoots may be induced to flower after the March equinox naturally, and the floral bud formation occurs in two to three waves from May to October. We conducted experiments on photoperiodic regulation of floral bud formation from June to Dec. 2009 and tested the feasibility of off-season production in 2011. Shortening summer daylength to 8 h inhibited the areoles at the distal end of the shoots to develop into floral buds and promoted sprouting at the proximal ends of the shoots. Night-breaking treatment between the September equinox and the winter solstice led to floral bud formation. The critical daylength seemed to be ≈12 h, and night-breaking treatment would be applicable between the September and the next March equinoxes to produce off-season crops. The duration of night-breaking required for flower differentiation was longer in the cooler than in the warmer season. Four weeks of night-breaking treatment was sufficient to promote flowering in late fall (mid-October to mid-November), but 3 months were required to generate similar result in the winter and early spring (January to March) in southern Taiwan.
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Chamua, M., P. K. Bhuyan, P. Subrahmanyam, and S. C. Garg. "Diurnal, seasonal, latitudinal and solar cycle variation of electron temperature in the topside F-region of the Indian zone ionosphere." Annales Geophysicae 25, no. 9 (October 2, 2007): 1995–2006. http://dx.doi.org/10.5194/angeo-25-1995-2007.
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Abstract. Electron temperature Te observed by the SROSS C2 satellite at equatorial and low latitudes during the low to high solar activity period of 1995–2001 at the height of ~500 km is investigated in terms of local time, season, latitude, solar sunspot number Rz and F10.7 cm solar flux. The satellite covered the latitude belt of 31° S–34° N and the longitude range of 40°–100° E. The average nighttime (20:00–04:00 LT) Te varies between 750–1200 K and then rises sharply in the sunrise period (04:00–06:00 LT) to the morning high from 07:00 to 10:00 LT and attains a daytime (10:00–14:00 LT) average of 1100–2300 K. The morning enhancement is more pronounced in the equinoxes. A secondary maximum in Te is also observed around 16:00–18:00 LT in the June solstice and in the equinoxes. Daytime electron temperature was found to be higher in autumn compared to that in spring in all latitudes. Between the solstices, the amplitude of the morning enhancement is higher in winter compared to that in summer. Both day and nighttime Te observed by the SROSS C2 satellite bears a positive correlation with solar activity when averaged on a shorter time scale, i.e. over the period of a month. But on a longer time scale, i.e. averaged over a year, the daytime electron temperature gradually decreases from 1995 till it reaches the minimum value in 1997, after which Te again continues to rise till 2001. The variations are distinctly seen in summer and in the equinoxes. The sunspot activity during solar cycle 23 was minimum in 1996 and maximum in 2000. Annual average electron temperature, therefore, appears to follow the variation of solar activity with a time lag of about one year, both at the bottom and top of solar cycle 23, indicating an inherent inertia of the ionosphere thermosphere regime to variations in solar flux.
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Sweatman, Martin B., and Alistair Coombs. "Decoding European Palaeolithic Art: Extremely Ancient knowledge of Precession of the Equinoxes." Athens Journal of History 5, no. 1 (January 31, 2019): 1–30. http://dx.doi.org/10.30958/ajhis.5-1-1.
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Walker, G. O., J. H. K. Ma, and E. Golton. "The equatorial ionospheric anomaly in electron content from solar minimum to solar maximum for South East Asia." Annales Geophysicae 12, no. 2/3 (January 31, 1994): 195–209. http://dx.doi.org/10.1007/s00585-994-0195-0.
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Abstract. Median hourly, electron content-latitude profiles obtained in South East Asia under solar minimum and maximum conditions have been used to establish seasonal and solar differences in the diurnal variations of the ionospheric equatorial anomaly (EIA). The seasonal changes have been mainly accounted for from a consideration of the daytime meridional wind, affecting the EIA diffusion of ionization from the magnetic equator down the magnetic field lines towards the crests. Depending upon the seasonal location of the subsolar point in relation to the magnetic equator diffusion rates were increased or decreased. This led to crest asymmetries at the solstices with (1) the winter crest enhanced in the morning (increased diffusion rate) and (2) the same crest decaying most rapidly in the late afternoon (faster recombination rate at lower ionospheric levels). Such asymmetries were also observed, to a lesser extent, at the equinoxes since the magnetic equator (located at about 9°N lat) does not coincide with the geographic equator. Another factor affecting the magnitude of a particular electron content crest was the proximity of the subsolar point, since this increased the local ionization production rate. Enhancements of the EIA took place around sunset, mainly during the equinoxes and more frequently at solar maximum, and also there was evidence of apparent EIA crest resurgences around 0300 LST for all seasons at solar maximum. The latter are thought to be associated with the commonly observed, post-midnight, ionization enhancements at midlatitudes, ionization being transported to low latitudes by an equatorward wind. The ratio increases in crest peak electron contents from solar minimum to maximum of 2.7 at the equinoxes, 2.0 at the northern summer solstice and 1.7 at northern winter solstice can be explained, only partly, by increases in the magnitude of the eastward electric field E overhead the magnetic equator affecting the [E×B] vertical drifts. The most important factor is the corresponding increase in ionization production rate due to the increase in solar radiation flux. The EIA crest asymmetries observed at solar maximum were less significant, and this is probably due to the corresponding increase in ionization densities leading to an increase of the retarding effect of ion-drag on the daytime meridional winds.
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Hussien, Fayrouz, Essam Ghamry, and Adel Fathy. "A Statistical Analysis of Plasma Bubbles Observed by Swarm Constellation during Different Types of Geomagnetic Storms." Universe 7, no. 4 (April 6, 2021): 90. http://dx.doi.org/10.3390/universe7040090.
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Based on the observations of Ionospheric Bubble Index (IBI) data from the Swarm mission, the characteristics of plasma bubbles are investigated during different types of geomagnetic storms recorded from 2014 to 2020. The geometrical constellation of the Swarm mission enabled us to investigate the altitudinal profile of the IBIs during different activity levels in a statistical mean. Results show that the majority of IBIs associated with moderate storms are observed at low altitudes and the probability of observing IBIs at high altitudes (Swarm-B) increases with the increase in storm level. This is confirmed by observing the F2 layer peak height (hmF2) during super storm events at larger altitudes using COSMIC data. The maximum number of IBIs is recorded within the South Atlantic Anomaly (SAA) region with a long duration time and tends to increase only during dusk time. Both the large duration time and number of IBIs over the South Atlantic Anomaly (SAA) suggest that the gradient in the electron density and the depression in the magnetic field are the main factors controlling IBI events. Also, the IBIs at high altitudes are larger at sunset and at low altitudes pre-midnight. In addition, the occurrence of IBIs is always larger in the northern hemisphere than in the southern hemisphere irrespective of the type of storm, as well as during the summer months. Moreover, there is no correlation between the duration time of IBIs and both the altitudinal observation of the IBIs and the storm type. Seasonal occurrence of IBIs is larger during equinoxes and vice versa during solstices irrespective of both the type of storm and the altitude of the satellite. The large number of IBIs during equinoxes agrees with the previous studies, which expect that the large electron density is a developer of steeper ∇n. Large occurrences of super storm IBIs observed within the pre-midnight during summer and at sunset during equinoxes are a novel observation that needs further investigation. Also, the majority of IBIs are observed a few hours after geomagnetic substorms, which reflects the role of the Disturbance Dynamo Electric Field (DDEF) as a main driver of IBIs.
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Gullberg, Steven R. "Marking Time in the Inca Empire." Journal of Skyscape Archaeology 1, no. 2 (December 3, 2015): 217–41. http://dx.doi.org/10.1558/jsa.v1i2.28257.
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The Incas worshipped the Sun with light and shadow effects in their constructs commonly denoting such events as the solstices and equinoxes. They used these orientations, as well as solar pillars, to mark time passage for purposes of crop management and religious festivals. New research was conducted and photo-documentation of Inca intentional light and shadow effects is presented. Data was examined in a cultural context and supports a well-developed calendrical system. Several examples are examined within.
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dos Santos Godoi, Valdir Monteiro. "The Precession of the Perihelion of Mercury Explained by Celestial Mechanics of Laplace." Evolving Trends in Engineering and Technology 3 (December 2014): 11–18. http://dx.doi.org/10.18052/www.scipress.com/etet.3.11.
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We calculate in this article an exact theoretical value obtained classically for the secular precession of the perihelion of Mercury, followed by the theory of Stockwell, based on planetary theory of Laplace, your Mécanique Céleste: found 5600’’.84 of arc per century for the angular velocity of the longitude of the perihelion of Mercury, dω/dt, adding to the precession of the equinoxes of the Earth relative to the beginning of the year 1850, as calculated by Stockwell.
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Andrioli, V. F., D. C. Fritts, P. P. Batista, B. R. Clemesha, and D. Janches. "Diurnal variation in gravity wave activity at low and middle latitudes." Annales Geophysicae 31, no. 11 (November 29, 2013): 2123–35. http://dx.doi.org/10.5194/angeo-31-2123-2013.
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Abstract. We employ a modified composite day extension of the Hocking (2005) analysis method to study gravity wave (GW) activity in the mesosphere and lower thermosphere using 4 meteor radars spanning latitudes from 7° S to 53.6° S. Diurnal and semidiurnal modulations were observed in GW variances over all sites. Semidiurnal modulation with downward phase propagation was observed at lower latitudes mainly near the equinoxes. Diurnal modulations occur mainly near solstice and, except for the zonal component at Cariri (7° S), do not exhibit downward phase propagation. At a higher latitude (SAAMER, 53.6° S) these modulations are only observed in the meridional component where we can observe diurnal variation from March to May, and semidiurnal, during January, February, October (above 88 km) and November. Some of these modulations with downward phase progression correlate well with wind shear. When the wind shear is well correlated with the maximum of the variances the diurnal tide has its largest amplitudes, i.e., near equinox. Correlations exhibiting variations with tidal phases suggest significant GW-tidal interactions that have different characters depending on the tidal components and possible mean wind shears. Modulations that do not exhibit phase variations could be indicative of diurnal variations in GW sources.
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Lyatsky, W., and A. M. Hamza. "Seasonal and diurnal variations of geomagnetic activity and their role in Space Weather forecast." Canadian Journal of Physics 79, no. 6 (June 1, 2001): 907–20. http://dx.doi.org/10.1139/p01-049.
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A possible test for different models explaining the seasonal variation in geomagnetic activity is the diurnal variation. We computed diurnal variations both in the occurrence of large AE (auroral electrojet) indices and in the AO index. (AO is the auroral electrojet index that provides a measure of the equivalent zonal current.) Both methods show a similar diurnal variation in geomagnetic activity with a deep minimum around (37) UT (universal time) in winter and a shallower minimum near 59 UT in equinoctial months. The observed UT variation is consistent with the results of other scientists, but it is different from that expected from the RussellMcPherron mechanism proposed to explain the seasonal variation. It is suggested that the possible cause for the diurnal and seasonal variations may be variations in nightside ionospheric conductivity. Recent experimental results show an important role for ionospheric conductivity in particle acceleration and geomagnetic disturbance generation. They also show that low ionospheric conductivity is favorable to the generation of auroral and geomagnetic activity. The conductivity in conjugate nightside auroral zones (where substorm generation takes place) is minimum at equinoxes, when both auroral zones are in darkness. The low ionospheric conductivity at equinoxes may be a possible cause for the seasonal variation in the geomagnetic activity with maxima in equinoctial months. The diurnal variation in geomagnetic activity can be produced by the UT variation in the nightside ionospheric conductivity, which in winter and at equinoxes has a maximum around 45 UT that may lead to a minimum in geomagnetic activity at this time. We calculated the correlation patterns for the AE index versus solar-wind parameters inside and outside the (27) UT sector related to the minimum in geomagnetic activity. The correlation patterns appear different in these two sectors indeed, which is well consistent with the UT variation in geomagnetic activity. It also shows that it is possible to improve significantly the reliability of the Space Weather forecast by taking into account the dependence of geomagnetic activity not only on solar-wind parameters but also on UT and season. Our test shows that a simple account for the dependence of geomagnetic activity on UT can improve the reliability of the Space Weather forecast by at least 50% in the 27 UT sector in winter and equinoctial months. PACS No.: 91.25Le
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Benjamin, Roy. "What Era’s O’ering?: The Precession of the Equinoxes in Finnegans Wake." James Joyce Quarterly 48, no. 1 (2010): 111–28. http://dx.doi.org/10.1353/jjq.2010.0024.
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Smith, Anne K., Rolando R. Garcia, Andrew C. Moss, and Nicholas J. Mitchell. "The Semiannual Oscillation of the Tropical Zonal Wind in the Middle Atmosphere Derived from Satellite Geopotential Height Retrievals." Journal of the Atmospheric Sciences 74, no. 8 (July 18, 2017): 2413–25. http://dx.doi.org/10.1175/jas-d-17-0067.1.
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Abstract The dominant mode of seasonal variability in the global tropical upper-stratosphere and mesosphere zonal wind is the semiannual oscillation (SAO). However, it is notoriously difficult to measure winds at these heights from satellite or ground-based remote sensing. Here, the balance wind relationship is used to derive monthly and zonally averaged zonal winds in the tropics from satellite retrievals of geopotential height. Data from the Aura Microwave Limb Sounder (MLS) cover about 12.5 yr, and those from the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) Sounding of the Atmosphere Using Broadband Emission Radiometry (SABER) cover almost 15 yr. The derived winds agree with direct wind observations below 10 hPa and above 80 km; there are no direct wind observations for validation in the intervening layers of the middle atmosphere. The derived winds show the following prominent peaks associated with the SAO: easterly maxima near the solstices at 1.0 hPa, westerly maxima near the equinoxes at 0.1 hPa, and easterly maxima near the equinoxes at 0.01 hPa. The magnitudes of these three wind maxima are stronger during the first cycle (January at 1.0 hPa and March at 0.1 and 0.01 hPa). The month and pressure level of the wind maxima shift depending on the phase of the quasi-biennial oscillation (QBO) at 10 hPa. During easterly QBO, the westerly maxima are shifted upward, are about 10 m s−1 stronger, and occur approximately 1 month later than those during the westerly QBO phase.
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Leibowicz, Ivan, Ricardo Moyano, Alejandro Ferrari, Félix Acuto, and Cristian Jacob. "Archaeoastronomy on Inca Sites in the Argentine Northwest." Journal of Skyscape Archaeology 2, no. 2 (February 10, 2017): 165–87. http://dx.doi.org/10.1558/jsa.27601.
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In this paper, we present results of astronomical and landscape analysis at four Inca sites located in the Nevados de Cachi area, North Calchaquí Valley, Salta Province, Argentina. Selection criteria took into consideration the existence of certain traits of paramount importance amongst Inca architecture, such as ushnu platforms, gnomons and a particularly interesting petroglyph located in a high-altitude sanctuary. Results show that the location and spatial layout of certain Inca settlements, as well as certain structures within, were designed and located based on astronomical observation patterns centred on solstices, equinoxes and lunar standstills.
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Prieto, Raidel Báez, and Francisco Henrique de Oliveira. "Study of solar radiation in the equinoxes and solstices in the City of Havana, Cuba." Ciência e Natura 40 (May 11, 2018): 36. http://dx.doi.org/10.5902/2179460x30674.
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Solar radiation is of utmost importance for life on earth and for carrying out different human and natural activities, such as the studies carried out for agriculture. The objective of this work is to calculate, from formulations, the incidence of solar radiation. Solar energy will be calculated in Havana City, Cuba, during the equinoxes and solstices, as well as the variation that exists during the different seasons of the year. A study was carried out every 3 hours: 6am, 9am, 12m, 3pm and 6pm, (average solar time) creating a table with real values of this energy, obtaining maps of light and shadow planes.
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Baranyi, T., and A. Ludmány. "Role of the solar main magnetic dipole field in the solar-tropospheric relations. Part II. Dependence on the types of solar sources." Annales Geophysicae 13, no. 8 (August 31, 1995): 886–92. http://dx.doi.org/10.1007/s00585-995-0886-1.
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Abstract. Two criteria have previously been reported for efficient solar-tropospheric relations through corpuscular channels: the appropriate Sun-Earth attitude (equinoxes) and the mutual orientations of the terrestrial and solar main magnetic dipole fields. The effect also depends on the geographical position. The present paper reports a further criterion. The solar-meteorological correlations also depend on the solar origin of the given corpuscular impact: disturbances originating from the polar and equatorial regions release opposite behaviours. We conclude that the solar-meteorological relations can only be described by taking into account the specific spatial situations and polarity distributions.
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Amaechi, P. O., E. O. Oyeyemi, and A. O. Akala. "Variability of the African equatorial ionization anomaly (EIA) crests during the year 2013." Canadian Journal of Physics 97, no. 2 (February 2019): 155–65. http://dx.doi.org/10.1139/cjp-2017-0985.
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This paper discusses the variability of the position and magnitude of the crests of African Equatorial Ionization Anomaly during noon and post sunset periods. Total electron content data covered the year 2013, and were obtained from a chain of global positioning system receivers in both hemispheres around 37°E longitude. Local magnetometer data were used to infer the direction and magnitude of the E × B drift, while the solar extreme ultraviolet proxy index was used as a measure of solar activity. It was found that the time of formation of both crests varied from 1400 to 1700 local time. Additionally, the position of the crests was found to be asymmetric with respect to the magnetic equator. During the noon period, the position of the northern and southern crests varied from 4.91° to 7.36° and −9.17° to −12.62°, respectively. During the post-sunset period, it varied from 8° to 11.7° and −9° to −16°, respectively. Seasonally, with reference to the magnetic equator, both crests moved poleward during equinoxes and collapsed towards the equator during winter and summer. Equinoxes recorded the greatest crest magnitude followed by winter then summer over both hemispheres during the noon period. However, this trend persisted over the northern crest only during the post-sunset period. Overall, during the noon period, we recorded correlation coefficients of 0.67 and 0.68 between crest magnitudes and ΔH, a proxy for equatorial electrojet current, and 0.88 and 0.81 between crest positions and ΔH, for the northern and southern crests, respectively. During the Halloween day storm of 30 October 2013, a westward electric field inhibited the development of the post-sunset crests.
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Kashiwaya, Kenji, Timothy C. Atkinson, and Peter L. Smart. "Periodic Variations in Late Pleistocene Speleothem Abundance in Britain." Quaternary Research 35, no. 2 (March 1991): 190–96. http://dx.doi.org/10.1016/0033-5894(91)90066-e.
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AbstractTemporal change in the growth of speleothems in the United Kingdom during the past 150,000 years is shown to be related to the insolation variation by the Milankovitch theory. The speleothem data compiled by Gordon et al. (1989. Quarternary Research 31, 14–26) have two Milanokovitch frequencies: the ca. 40,000-yr period related to change in the earth's obliquity and the ca. 20,000-yr period related to the precession of the equinoxes. The abundance of speleothem growth was, in general, large during the last interglaciation and small during the last glaciation. In both periods, however, speleothem abundance was greater during periods of strong insolation and less during weak insolation.
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Arnaiz-Villena, Antonio, Marcial Medina, Valentín Ruiz-del-Valle, Adrian Lopez-Nares, Julian Rodriguez-Rodriguez, and Fabio Suarez-Trujillo. "The Ibero-Guanche (Latin) rock inscriptions found at Mt. Tenezara volcano (Lanzarote, Canary Islands, Spain): A Saharan hypothesis for Mediterranean/Atlantic Prehistory." International Journal of Modern Anthropology 2, no. 13 (July 7, 2020): 140–62. http://dx.doi.org/10.4314/ijma.v2i13.5.
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Two of the several rock script panels found at Mt. Tenezara volcano slope, Lanzarote Is. (Canary Islands) have been analyzed. Both of them contain a linear writing which corresponds to the ancient Iberian semi-sillabary discovered by Gomez-Moreno in 1949 AD, thus to Iberian-Guanche inscriptions which previously were referred as Latin. Ancient Iberian scripts have been found in France, Portugal, Spain and other Mediterranean places during the 1st millennium BC and the following four centuries AD; it may be possible that Iberian signs could have been taken or used at the same time at Africa. Even one of the semi-vertical panels considered as Lybic is in fact written in Iberian-Guanche characters. Also, Mt Tenezara shows Cart-ruts pointing to Equinoxes Sunrise. Findings are put in the context of a Sahara relatively rapid desiccation and a massive people migration to establish several classic and pre-classic civilizations, like Sumer, Egypt, Hittite, Hellenistic, Iberians, Lybic and Canary Islands Guanches, and possibly other Old Atlantic Celtic ones. Saharan Hypothesis is based on Geology, Columbia Shuttle (1981) infrared photographs that show prehistoric desert fertility, Prehistory, Anthropology and Linguistics. A fertile and heavily populated Sahara existed before 6,000 years BC.
Keywords: Sahara, Latin, Scripts, Canary Islands, Iberian, Guanche, Lybic, Lanzarote, Fuerteventura, Quesera, Cheeseboard, Pyramids, Berber, Africa, Punic, Roman, Tenerife, Equinox, Tunisia, Algeria, Canarian,, Calendar, Raetian, Lepontic, Venetian, Etruscan, Basque, Cart-ruts, Sitovo, Gradeshnitsa, Usko- Mediterranean, Language, Tenezara, Juan Brito
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Belmonte, Juan Antonio, and A. César González García. "Petra Revisited: An Astronomical Approach to the Nabataean Cultic Calendar." Culture and Cosmos 21, no. 1 and 2 (2017): 131–50. http://dx.doi.org/10.46472/cc.01221.0215.
Full textAbstract:
Petra, the ancient Nabataean capital, has been one of our main research objectives since the first field campaign on site in 1996. 1 In December 2015 a new visit to the city was made to coincide with the winter solstice. Historical, ethnographic, epigraphic and archaeological records are compared in order to gain an insight on the Nabataean calendar. From this multi-source analysis two main points arise: the importance of both equinoxes and winter solstice within the lunisolar calendar and the relevance of some processions and pilgrimages. These combined with illumination effects observed and broadcasted at the principal monuments of Petra, and new important hierophanies, predicted in previous campaigns,2 indicate the relevance of these dates at the time of the Nabataeans. Winter solstice was an important event in the Nabataean cultic calendar when a festival of the main deities of the city, the God Dushara and his partner the goddess Al-Uzza, was commemorated. This probably took the form of a pilgrimage, and related cultic activities, such as ascending from the temples at the centre of the city (presumably from Qsar el Bint and the Temple of the Winged Lions), to the Monastery (Ad-Deir) through an elaborated stone-carved processional way. The relevance of the spring and autumn equinox within the cultic calendar will also be emphasized in relationship to other sacred sites in Petra, such as the Zibb Atuff obelisks, and additional Nabataean sites.
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Belenkiy, Ari, and Eduardo Vila Echagüe. "History of one defeat: reform of the Julian calendar as envisaged by Isaac Newton." Notes and Records of the Royal Society 59, no. 3 (September 22, 2005): 223–54. http://dx.doi.org/10.1098/rsnr.2005.0096.
Full textAbstract:
Having been asked in February 1700 by The Royal Society to respond to G. W. Leibniz's letter from Hanover about the decision of the German states to accept a so-called ‘improved calendar’, Isaac Newton, then Master of the Mint, developed a proposal for the reform of the Julian and Ecclesiastical calendars that was later found among his unpublished manuscripts (now grouped as Yahuda MS 24). His calendar, if implemented, would have become for England a viable alternative to the Gregorian. Despite having a different algorithm, its solar part agrees with the latter until ad 2400 and is more precise in the long run, within a period of 5000 years. Although Newton's lunar algorithm is more elegant than the Gregorian, his Ecclesiastical calendar remained incomplete. We explain why blank spaces were left and data were changed in several of the manuscripts, discuss the time frame and the order in which Newton wrote different drafts of Yahuda MS 24, analyse their relation with three manuscripts from the Cambridge collection, and suggest a reason for Newton's delay and failure to press for the implementation of his calendar. Newton, as can be discerned from his statistical analysis of Hipparchus's equinox observations, can be credited, historically, with the first application of the technique known today as linear regression analysis and also with a remarkable guess about the ancient Greek observations of the equinoxes that recently has been confirmed.