Abstract
We had investigated the effects of solar/geomagnetic activities on the surface air temperature of Egypt. We used the monthly sunspot numbers, solar flare and flux, total solar irradiance and geomagnetic disturbances as solar and geomagnetic activity indicators. We considered monthly Egypt surface air temperature (ESAT) throughout the period 1881–2009, which covers 12 solar activity cycles. We found a negative correlation between ESAT and solar geomagnetic indices, as well as a positive correlation with total solar irradiance for the entire data set. We found that the sign of the correlation between ESAT and Rz depends on NorthSouth sunspot area, being positive when the Northern solar hemisphere is predominantly more active, and negative when more active is the southern hemisphere except for the cycle 13. The power spectra analyses have been applied to obtain the spectrum-cyclic behavior of ESAT, as well as for other parameters. The most pronounced power peaks were found around periods of 25.6,8.0,5.6,4.1,2.7,2.3 years, indicating a remarkable role of solar/geomagnetic activities on Egypt's temperatures. We concluded that the signature of solar activity effect may exist on surface air temperature of Egypt.
Highlights
The role of solar activity on global climate has been examined by many authors with climate models (e.g., Meehl et al, 2009), as well as by comparing statistically solar and global, or regional, climate records e.g. (Lean and Rind, 2008; Benestad and Schmidt, 2009)
In cycle 22, Figure (4k), aa shows a cyclic behavior of period ~3years with Egypt surface air temperature (ESAT), a negative correlation of ~(–0.4) with the same phase are observed for Rz, Solar Flares, Solar Flux and total solar irradiance at lag 8m
We have studied the dependence of Egypt surface air temperature (ESAT) on solar/geomagnetic activities over different time scales
Summary
The role of solar activity on global climate has been examined by many authors with climate models (e.g., Meehl et al, 2009), as well as by comparing statistically solar and global, or regional, climate records e.g. (Lean and Rind, 2008; Benestad and Schmidt, 2009). The precisely dated records allowed for the identification of a 10–30 year lag between solar forcing and temperature response, underlining the importance of indirect Sun–climate mechanisms involving ocean–induced changes in atmospheric circulation. (Kilcik et al, 2009) considered the temperatures at different mid latitude zones and flare index data for the period from January 1975 to the end of December 2005, which covers almost three solar cycles, (21st- 23rd) They found significant correlations between solar activity and surface air temperature over the 50o–60o and 60o –70o zones for cycle 22 and over the 30o – 40o, 40o –50o, and 50o –60o zones for cycle 23, but have not any significant correlation for the cycle 21. The present study offers the possibility to quantitatively evaluate the relationship between solar/geomagnetic activities and surface air temperature over a well–defined geographic area throughout the period 1881-2009
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