| Abstract : | The Sun rotates differentially from the equator towards the pole as it is not a rigid body. In the past, many studies have been done based on the rotation profile of the Sun for the photosphere using different techniques and the photospheric differential rotation is now quite well established. The differential rotation property was studied individually and compared with the photospheric values in the chromosphere and solar corona. However, they also give contradictory results for different data sources and methods. Due to a lack of detailed study on the chromosphere, its dynamics still need to be understood. The beneficial aspect of this project is the incorporation of a century-long KoSO Ca II K data (1907-2007) which helps us study the rotation profile in the chromosphere in different phases of solar cycles. We have applied the image correlation technique on the entire ~ 100-year data for this purpose by taking sets of two consecutive day images. From the analysis, we found that the chromosphere rotates 1.52% faster than the photosphere but also rotates less differentially by comparing our result with previously obtained photospheric values. We also applied our method to MDI white light data and other Ca II K data sources (Meudon and PSPT/Rome) to validate both method and data. Also, we investigated the solar cycle dependency of differential rotation parameters and the north-south asymmetry of the solar rotation profile.
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