Thesis (Ph.D.) - Cairo University - Faculty of Science - Department of Astronomy and Meteorology

The current work in this thesis focus on the connection between solar output, and atmospheric circulation, as Teleconnections study. Concrete evidences for the control of the sun over the NAO index during solar cycles 23 and the present weak cycle 24, there is one to one correspondence between sunspot number peaks and depressions which force the NAO index to switch positively and negatively respectively. The prolonged negative NAO index in 2006 can be attributed to minimum solar activity. North Atlantic Oscillations are actually a reflection of sunspot number oscillations. This finding opens the door for the future prediction of NAO index. Switch to negative index occurred in 1878 and 1960s owing to weak cycles 12 and 20 respectively. The latter caused changes in the general wind circulation and led to a sudden sharp rises in Equatorial and East African lakes and cooling of the Earth. Using regional climate model Rgcm4 experiment was designed hypothically to test the most sensitive contour for net surface radiation in Africa as a key parameter for surface fluxes with the atmosphere; it was found that the most sensitive pixel is located between 0-10 latitude and 20-40 longitude

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