Studies on variations in solar total and spectral irradiance

Abstract

The sun emits radiation in all possible wavelengths. This emitted energy can be measured wavelength wise ,SSI(solar spectral irradiance w/m^2/nm), or as a bulk ,TSI(total solar irradiancew/m^2 ) .TSI is the amount of solar energy received in watts on an area of 1 m^2 per sec kept normal to solar radiations at 1AU distance from sun .TSI per unit wavelength is SSI. Since from 1978 ,various nations have focused on the measurement of TSI by different satellites ACRIM I,II, ERBS,SOVA2 ,VIRGO etc. This data is stored by them in their individual databases, over last 33 years. This data is clubbed together to form a single database for solar irradiance, which is known as composite total solar irradiance(CTSI) The two important parameters of sun areCTSI and SSA where SSA is sunspot area measured in ppm(parts per million). Whenever sunspot appears CTSI decreases. SSA and CTSI shows phase relationship wrt each other. The phase difference between them is called as delay which is measuredindays. Determination of delay and study of its characteristics is called as delay analysis . Raw data for solar cycle 21,22,23 is used for data analysis. In analysis 27day averaged data is used. Delay between 27CTSI minima and 27SSA maxima is measured by simultaneously plotting 27CTSI and 27SSA.It is found that delay varies from 230 to+230 days over a period of3 solar cycles(ie solar cycle 21,22,23) ie 33 years. newline newline