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Day-to-Day Variability of H Component of Geomagnetic Field in Central African Sector Provided by Yaoundé-Cameroon Amber Station  [PDF]
Messanga Etoundi Honore, Kosh Djaka Comelo, Mbane Biouele Cesar
International Journal of Geosciences (IJG) , 2014, DOI: 10.4236/ijg.2014.510099
Abstract: The geomagnetic data obtained from Amber Network station in Cameroon have been used for this study. The variability of H component of geomagnetic field has been examined by using geomagnetic field data of X and Y components recorded at AMBER magnetometer station hosted by the Department of Physics of University of Yaoundé (3.87°N, 11.52°E). The day-to-day variability of the horizontal intensity of the geomagnetic field was examined and shows that the scattering of H component of magnetic field variation is more on disturbed than that on quiet condition. The signatures H of geomagnetic Sq and Sd variations in intensities in the geomagnetic element, has been studied. This study shows that the daytime variations in intensities of geomagnetic elements H, Sq(H) and Sd(H) respectively are generally greater than night-time ones. This paper interests answering the two questions: 1) how can geomagnetic variations be used to study the equatorial ionosphere electrodynamics and electrojet equatorial over Africa in general and Cameroon in particular? 2) How can geomagnetic variations be used to monitor and predict space weather events in Cameroon? This paper presents and interprets the results of H component of geomagnetic field variations during magnetic storms and on quiet days.
Sq (H) Solar Variation at Yaoundé-Cameroon AMBER Station from 2011 to 2014  [PDF]
Messanga Etoundi Honoré, Fatma Anad, Ngabireng Claude Marie, Mbane Biouele César
International Journal of Geosciences (IJG) , 2017, DOI: 10.4236/ijg.2017.84029
Abstract: This paper presents the earth’s magnetic field variations on quiet days using data from 2011 to 2014 provided by the AMBER station located at the University of Yaoundé 1 (Cameroon), whose geographic and geomagnetic coordinates are respectively: (3.87°N, 11.52°E) and (5.8°S, 83.1°E). The variability of the H horizontal component of the Earth’s magnetic field was examined using the North (X) and East (Y) components of the earth’s magnetic field. The H component is then used to calculate and analyze the diurnal, monthly and seasonal Solar quiet variations Sq (H) observed in Yaoundé-Cameroon during quiet magnetic days. The results obtained show that the Sq (H) variations are seasonal. e.g., in Spring the Sq (H) amplitude (~72 nT) is larger than that of Autumn (~69 nT). The maximum values of Sq (H) vary from 48.8 nT to 57.12 nT in summer and from 41 nT to 60 nT in winter from the years 2011 to 2014. In general, these maximum values are observed around 12:00 and 13:00 in local time. These results show that the morphology of Sq (H) in Yaoundé is presented as a function of seasons. Moreover, the Sq (H) values are negative during morning hours (01:00 - 06:00) and afternoon hours (18:00 - 24:00) in local time throughout all months and all seasons. This significant negative excursion of Sq (H) in Yaoundé during the night time might be due to other physical processes such as storms or thunderclouds or to the existence of a strong induced current in Yaoundé which can affect the ground-based instruments. By referring to the solar cycle 24, our results show that the Sq (H) amplitude varies with the solar activity. The aim of this work is to analyze the diurnal, monthly and seasonal variations of Sq (H) observed in Yaoundé from 2011 to 2014.
The 22-year cycle in the geomagnetic 27-day recurrences reflecting on the F2-layer ionization
E. M. Apostolov, D. Altadill,M. Todorova
Annales Geophysicae (ANGEO) , 2004,
Abstract: Solar cycle variations of the amplitudes of the 27-day solar rotation period reflected in the geomagnetic activity index Ap, solar radio flux F10.7cm and critical frequency foF2 for mid-latitude ionosonde station Moscow from the maximum of sunspot cycle 18 to the maximum of cycle 23 are examined. The analysis shows that there are distinct enhancements of the 27-day amplitudes for foF2 and Ap in the late declining phase of each solar cycle while the amplitudes for F10.7cm decrease gradually, and the foF2 and Ap amplitude peaks are much larger for even-numbered solar cycles than for the odd ones. Additionally, we found the same even-high and odd-low pattern of foF2 for other mid-latitude ionosonde stations in Northern and Southern Hemispheres. This property suggests that there exists a 22-year cycle in the F2-layer variability coupled with the 22-year cycle in the 27-day recurrence of geomagnetic activity. Key words. Ionosphere (mid-latitude ionosphere; ionosphere- magnetosphere interactions) – Magnetospheric physics (solar wind-magnetosphere interactions)
Day-to-Day Variability of H and Z Components of the Geomagnetic Field at the African Longitudes  [PDF]
T. N. Obiekezie,S. C. Obiadazie,G. A. Agbo
ISRN Geophysics , 2013, DOI: 10.1155/2013/909258
Abstract: The Day-to-day variability of the geomagnetic field elements at the African longitudes has been studied for the year 1987 using geomagnetic data obtained from four different African observatories. The analysis was carried out on solar quiet days using hourly values of the Horizontal, , and vertical, , geomagnetic field values. The results of this study confirm that Sq is a very changeable phenomenon, with a strong day-to-day variation. This day-to-day variation is seen to be superimposed on magnetic disturbances of a magnetospheric origin. 1. Introduction Changes in the magnetic environment of the Earth are of interest to those studying space weather and climate change, particularly in the upper atmosphere. The upper atmosphere is ionized by the Sun’s ultraviolet and X-radiation to create the ionosphere, and the free ions and electrons are moved by winds arising from the heating effects of the Sun. The currents in the ionosphere have magnetic effect on the ground and are monitored using magnetometers on the Earth surface. The records of any observatory show that on some days there are regular variations on the magnetic record while on other days the variation is irregular. The daily variations of the geomagnetic field when solar-terrestrial disturbances are absent are called solar quiet (Sq) variations [1]. These Sq variations are caused mainly by electrical currents in the upper atmosphere, at altitudes of about 110?km above the Earth surface [2]. Studies on solar quiet daily variation of the Earth’s magnetic field show that Sq on one day can be different from Sq of the next day in amplitude, phase, and focal latitude [3–5]. This change in Sq between two adjacent days is the day-to-day variability in Sq between the two days. This day-to-day variability has been highly attributed to changes in the ionospheric dynamo currents, which depend on the ionospheric conductivity and tidal winds, varying with solar radiation and ionospheric conditions [6, 7]. Hasegawa [8] examined the day-to-day changes of the quiet day variation and the ionospheric current systems for the second polar year and suggested that some or all the day-to-day variabilities in solar quiet daily variation (Sq) are due to variability in the positions of the foci of the ionospheric current systems rather than changes in the distribution of ionization and conductivity. Studies conducted by [9–16] clearly showed that the variability of Sq occurred at all hours of the day. Rabiu et al. [17] from their comprehensive study of Sq day-to-day variability at Addis Ababa, an equatorial electrojet
On the semi-annual, 27 day, variation in geomagnetic activity, cloud cover and surface temperature  [PDF]
Ian Edmonds
Physics , 2013,
Abstract: We develop a basic model of the time variation of geomagnetic activity and show that the model predicts, with decreasing levels of exactitude, the time variation of the ~27 day period components of geomagnetic aa index, cloud cover and surface temperature during several years near solar cycle minima. We interpret this as indicating that there is a connection between the ~27 day variation of geomagnetic activity and the ~27 day variations of cloud cover and surface temperature with the decreasing correlations between model variation and aa index, cloud cover and surface temperature variation due to delays and phase shifts between the three variables some of which are obvious, such as the 180 degree seasonal phase shift between cloud cover and surface temperature, and others less certain. We find that, while the components of cloud cover and surface temperature influenced by geomagnetic activity amount to, on average, about 20% of the overall variations, the influence may be several times higher during the semi-annual maxima in geomagnetic activity that occur around the equinoxes.
27-day variation of the GCR intensity based on corrected and uncorrected for geomagnetic disturbances data of neutron monitors  [PDF]
M. V. Alania,R. Modzelewska,A. Wawrzynczak,V. E. Sdobnov,M. V Kravtsova
Physics , 2015, DOI: 10.1088/1742-6596/632/1/012085
Abstract: We study 27-day variations of the galactic cosmic ray (GCR) intensity for 2005- 2008 period of the solar cycle #23. We use neutron monitors (NMs) data corrected and uncorrected for geomagnetic disturbances. Besides the limited time intervals when the 27-day variations are clearly established, always exist some feeble 27-day variations in the GCR 5 intensity related to the constantly present weak heliolongitudinal asymmetry in the heliosphere. We calculate the amplitudes of the 27-day variation of the GCR intensity based on the NMs data corrected and uncorrected for geomagnetic disturbances. We show that these amplitudes do not differ for NMs with cut-off rigidities smaller than 4-5 GV comparing with NMs of higher cut-off rigidities. Rigidity spectrum of the 27-day variation of the GCR intensity found in the uncorrected data is soft while it is hard in the case of the corrected data. For both cases exists definite tendency of softening the temporal changes of the 27-day variation's rigidity spectrum in period of 2005 to 2008 approaching the minimum of solar activity. We believe that a study of the 27-day variation of the GCR intensity based on the data uncorrected for geomagnetic disturbances should be carried out by NMs with cut-off rigidities smaller than 4-5 GV.
Association of a planetary tidal effect with the time variation of the ~13.5 day component of geomagnetic activity  [PDF]
I. R. Edmonds
Physics , 2014,
Abstract: We show that there is a previously unreported quad-annual variation in the ~13.5 day component of the aa index of geomagnetic activity. We derive a model based on the planetary tidal effect at the solar surface due to Mercury and Jupiter that, when combined with an equinoctial response of the magnetosphere, predicts the times of occurrence of predominantly quad-annual variation or predominantly semi-annual variation in the ~13.5 day component of the aa index. In support of the model we show that, during years when the quad-annual variation in the ~13.5 day component of aa index is predominant there is a large component at the 88 day periodicity of Mercury in the ~13.5 day component of solar wind speed. As further support for the model we establish that significant peaks in the aa index spectrum are due to an 88 day modulation of 27 day period solar activity. The model also predicts the occurrence of planetary tidal effect maximum in anti-phase with solar cycle maximums around 1970 and we show this is consistent with prior observations of higher solar emissions during the 1975 solar cycle minimum than in the following solar cycle maximum. This effect offers a possible explanation of the reduced solar cycle maximums around 1970 and during the Dalton Minimum.
Insect frass in Baltic amber  [PDF]
Matti Nuorteva,Kari A. Kinnunen
Bulletin of the Geological Society of Finland , 2008,
Abstract: Inclusions of wood debris loosened from pine-like trees are abundant in Baltic amber of Eocene and Oligocene age. The possibilities to find insect frass and excrement among wood debris are outlined and some examples are given. Comparison with the frass and excrement produced by present-day insects provide a possibility to identify insects even though their fossils are lacking. This information can be used to characterize former forest environments. Amber forests may have also covered Southern Finland, and this possibility is discussed. Furthermore, the presence of wood debris may be utilized to recognize amber fakes, which is important for both gem trade and paleontology. It is proposed that databases and identification keys of frass and excrement should be constructed.
The Geomagnetic Effects of Solar Activity as Measured at Ouagadougou Station  [PDF]
Aristide Marie Frédéric Gyébré, Doua Allain Gnabahou, Frédéric Ouattara
International Journal of Astronomy and Astrophysics (IJAA) , 2018, DOI: 10.4236/ijaa.2018.82013
Abstract: The coronal mass ejections (CMEs) produce by Sun poloidal magnetic fields contribute to geomagnetic storms. The geomagnetic storm effects produced by one-day-shock, two-days-shock and three-days-shock activities on Ouagadougou station F2 layer critical frequency time variation are analyzed. It is found that during the solar minimum and the increasing phases, the shock activity produces both positive and negative storms. The positive storm is observed during daytime. At the solar maximum and the decreasing phases only the positive storm is produced. At the solar minimum there is no three-days-shock activity. During the solar increasing phase the highest amplitude of the storm effect is due to the one-day-shock activity and the lowest is produced by the two-days-shock activity. At the solar maximum phase the ionosphere electric current system is not affected by the shock activity. Nevertheless, the highest amplitude of the storm effect is caused by the two-days-shock activity and the lowest by the one-day-shock activity. During the solar decreasing phase, the highest amplitude provoked by the storm is due to the three-days-shock activity and the lowest by the one-day-shock activity.
The Effect of Counseling Provided on the Second Post Partum Day Through Home Visits on Breastfeeding Success in Turkey: Randomized, Controlled Trial  [cached]
Nuriye Büyükkayac? Duman
Journal of Nursing Education and Practice , 2012, DOI: 10.5430/jnep.v2n1p91
Abstract: Background: It is known that breastfeeding offers numerous benefits for the mothers and their babies. In this sense, “Promotion of Breast Milk and Baby Friendly Hospital” initiation was started in 1992 all over the world. Systematically trainings are provided at the baby friendly hospitals in order to promote breastfeeding and to continue breastfeeding behavior. However, the efficacy of the planned counseling services for breastfeeding provided following the birth at the baby friendly hospitals reduces due to the early discharge. The present research was conducted in order to determine the effect of counseling provided on the second post partum day through home visits on breastfeeding success. Methods: Design: Randomized-controlled. The research was consisted of 100 women (intervention group=50, control group=50) who resided in orum Province, Turkey. Women of the intervention group were provided with trainings and counseling related to breastfeeding at the hospital after birth and at home following the discharge (on the second postpartum day). The data were collected using Descriptive Data Collection Form used to obtain information about mothers’ characteristics, Breastfeeding Evaluation Forms used to analyze the aspects about breastfeeding and LATCH Breastfeeding Charting System. Results: The mean LATCH scores and LATCH subscale scores of the intervention group were higher on the second postpartum day than those in the control group. Moreover, the rate of babies fed only with breast milk by the women in the intervention group during the last 24 hours was higher than those in the control group. The difference between intervention and control group was significant in terms of breastfeeding success on the second postpartum day, in favor of intervention group (p<0.05). Conclusions: Counseling given through home visits on the second postpartum day affected breastfeeding success positively.
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