Secular and seasonal changes in transfer function at Guangzhou geomagnetic observatory
- 4 Downloads
Time changes in transfer functions of short period geomagnetic variations in 28 years from 1960 through 1987 are studied, systemically and in detail in this paper. The results indicate that: (1) It is evident that seasonal and secular changes in the transfer functionsA at exist the Guangzhou Geomagnetic observatory. The characteristics for seasonal changes are large in summer and smaller in winter with main cycles of 12 and 6 months. The characteristic for secular change is a descend with a rate of 0.0025 per year. The seasonal and secular changes in transfer functionsB are not evident. (2) The direction of Parkinson vector at Guangzhou geomagnetic observatory is clearly affected by the ocean, and is associated with coastal effect. (3) The values of the transfer function A and B are related to geomagnetic activity ata=0.05. Secular change is not related to geomagnetic activity, maybe it is affected in a great measure by earth conductivity change.
Key wordsgeomagnetic short-period variation transfer function secular changes seasonal changes the coastal effect
Unable to display preview. Download preview PDF.
- Chen, P. F., 1981. A search for correlation between time change in North Taiwan.J. Geomag. Geoelectr.,33, 635–643.Google Scholar
- Chen, P. F., 1982. Lunar semi-monthly variation in the phase difference of the geomagnetic daily variations between two coastal stations.Acta Geophysica Sinica,25, 1, 41–49 (in Chinese).Google Scholar
- Gong, S. J., 1985. Anomalous changes in transfer functions and the 1976 Tangshan earthquake (M s=7.8).J. Geomag. Geoelectr.,37, 503–508.Google Scholar
- Gong, S. J., 1987. Parkinson vectors at the geomagnetic stations in Guangdong province and the time-dependent changes of their ratio at Guanzhou station both before and after the Heyuan earthquake.Journal of Seismological research,10, 5, 575–5892 (in Chinese).Google Scholar
- Parkinson, W. D., 1962. The influence of continents and oceans on geomagnetic variations.Geophys, J. R. astr. Soc.,6, 441–449.Google Scholar
- Qi, G. Z., Zhan, Z. J., Hou, Z. Z., Fan, G. H., Wang, Z. G. and Bia, T. X., 1981. Anomalies of short-period geomagnetic variations and distribution of high Conductivity layer in the Bohai sea area.Scientia Sinica,7, 869–879 (in Chinese).Google Scholar
- Rikitake, T., 1976. Crustal dilatancy and geomagnetic variations of short-period.J. Geoman. Geoelec.,28, 145–156.Google Scholar
- Sano, Y. and Nakajima. S., 1982. Secular and seasonal variations of transfer functions at Kakioka from March 1977 to April 1981.Memo Kakioko Mag Obs.,19, 33–50.Google Scholar
- Schmucker, U., 1970. Anomalies of geomagnetic variation in the Southwestern United States.Bull. Scrips Inst. Oceanogr.,13, 1–221.Google Scholar