Solar Activity Effects on Cloud Cover over Indonesia

Proceedings of The 9th Asian-Pacific Regional IAU Meeting 2005, 52–53 (2005)

Solar Activity Effects on Cloud Cover over Indonesia
J. T. Nugroho and T. Djamaluddin
National Institute of Aeronautics and Space (LAPAN) Bandung, Indonesia


ABSTRACT
It is known the relationship between global cloud cover and solar activity. It is interesting to study the solar signal on cloud cover over Indonesia, where the atmospheric convection is very active. We divide the analysed region in Indonesia based on their climate patterns, i.e. monsoon, equatorial, and local patterns. We also analysed the data based on the position on the sun, related to the season, i.e. June-August (JJA,dry season in monsoon pattern), September-November (SON, transition dry to wet),December-February (DJF, wet seasons in monsoon pattern), and March-May (MAM,transition wet to dry). Using the Weighted Wavelet Z-transform (WWZ), we analysed the dominant periodicity of about 11 year, indicating the solar signal. It is found that solar signal does not appear on all regions with different climate pattern or seasonal time ranges. The stronger solar signal appears over region with monsoon pattern and during dry seasons, when local or regional effects is least.
Key words: solar activity – cloud cover – ENSO signal