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 geomagne...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.展开更多
文摘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.
基金jointly funded by the Strategic Priority Research Program of Chinese Academy of Sciences grant number XDB40030205the National Natural Science Foundation of China grant numbers 91737306,41675100,and U1811464。
