27-day variations found in lightning activity and cloud amount, and thier relationship to the solar cycle
Abstract
Lightning activity based on the ELF measurement in the frequency range f 1-100 Hz and the outgoing longwave Radiation (OLR), an indicator of cloud amount, are examined about their periodicity in the periodic range of about one month. The ELF Schumann resonance (SR) power shows about 27-day periodicity in solar maximum years and it becomes elongated toward solar minimum. On the other hand, OLR shows same kind of 27-day periodicity in solar maximum years, but only in the Western Pacific Warm Pool area. Both the spectra of SR and OLR have a peak around 35-day in solar minimum years. The average spectrum of OLR in solar maximum years also shows an enhancement in the range of MJO period, that is, 50-60 days. Long-term variations in the tropospheric phenomena, including the 11-year cycle, are generally investigated from monthly or even yearly averaged data, but the present results may suggest an alternative possibility: short-period variations could modulate longer periodic phenomena. It is also found that the day-to-day SR power variations at different UT, which nearly represent activities of lightning at different longitude, are synchronized for about one-month periodicity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMAE41B..02T
- Keywords:
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- 0320 ATMOSPHERIC COMPOSITION AND STRUCTURE / Cloud physics and chemistry;
- 3304 ATMOSPHERIC PROCESSES / Atmospheric electricity;
- 3305 ATMOSPHERIC PROCESSES / Climate change and variability;
- 3324 ATMOSPHERIC PROCESSES / Lightning