The Houw Liong* and Plato Martuani Siregar**
*Department of Physics,FMIPA, ITB
**Department of Geophysics and Meteorology,FITB,ITB, Bandung, INDONESIA
From various geographical stations in the Indonesian Archipelago, anomalies of yearly rainfall were collected and plotted against the anomalies of yearly sunspot numbers between 1948 and 2003. It is seen that there is a strong correlation between sunspot numbers and the various geophysical variables, such as the mean temperature of Earth, the cloud cover, the sea surface temperature and the rainfall throughout the regions. The ability of cosmic ray particles to penetrate the earth’s atmosphere is limited by the earth’s magnetic field. In addition, during sunspot maximum the magnetic field of the solar wind increases and this in turn strongly reduces the flux of cosmic rays that reach the earth.
A correlation exists between cosmic rays, formation of clouds and climate as some researchers suggest. This paper shows that the knowledge of sunspot numbers can be used to predict extreme climate and weather in Indonesia.
The relative positions of the sun in the sky during the seasons, as well as the cycles of solar activity influence the weather and climate throughout the Indonesian archipelago. Solar irradiance increases with higher solar activity. This in turn increases the solar wind which consists of charged particles emitted by the sun which could alter the interplanetary magnetic field, and hence the intensity of cosmic rays reaching the earth. The cosmic ray intensity increases with higher solar activity. Thus the solar activity is often considered as the dominant factor that determines the dynamics of climate(1,2). The dynamics of earth’s atmosphere and oceans, evaporation, clouds formation and rainfall, are influenced by the solar energy entering the earth. Several studies indicate that strong correlations exist between the cloud cover and the intensity of cosmic rays.3)
Both phenomena may affect the climate, for example during 1645 – 1715 exceptionally low solar activity (also known as the Maunder minimum) led to low temperatures causing what is known as the little ice age.
The present study shows that there is a strong correlation between rainfall in the Archipelago and sunspot numbers.
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