The Solar Signal of the 11-Year Sunspot Cycle in the Stratosphere: Differences between the Northern and Southern Summers.

Abstract

The size of the changes of the stratospheric heights and temperatures which can be attributed to the 11-year sunspot cycle (SSC) is discussed with emphasis on the summer seasons. It is pointed out that the signal is strong and consistent during the northern summer, but weak during the southern summer, January/February. During this time of year the northern winters are dynamically very disturbed and the global signal of the SSC is modulated by the QBO.The study puts earlier work on a firmer ground and gives the community of modellers who simulate the solar signal with GCMs quantitative values for comparison.

On the signal of the 11-year sunspot cycle in the stratosphere and its modulation by the quasi-biennial oscillation

“…At the same time, the solar signal during the southern (b), same as Fig. 4(a), but for the WEST PHASE, right-hand side panels (n = 19) (NCEP/NCAR re-analyses, 1968-2002. summer is much reduced compared to the results obtained during northern summer.…”

“…This phenomenon maximizes during late winter. The stratospheric arctic warmings are connected with intense downwelling (adiabatic warming) over the Arctic and at the same time with upwelling (and connected adiabatic cooling) over the subtropics and tropics of both hemispheres (Labitzke, 2002;Salby and Callaghan, 2003). Therefore, compared to the east phase, the solar signal of the southern summer is disturbed here during west phase winters in January/ February.…”

“…Left: years in the EAST PHASE of the QBO (n = 16); right: years in the WEST PHASE (n = 19). The numbers indicate the respective years; r= correlation coe cient; T = temperature di erences between solar maxima and minima(NCEP/NCAR re-analyses, 1968-2002.…”

“…Meridional proÿles (60N-60S) of the detrended zonal mean 30-hPa height di erences (gpm) between solar maxima and minima (2-month means); dashed: for the EAST phase, solid for the WEST Phase(NCEP/NCAR re-analyses, 1968-2002.…”

Solar Variation and Stratospheric Response

“…The upper panels show all years, the middle panels only years in the east phase of the QBO, and the lower panels only years in the west phase of the QBO(NCEP/NCAR re-analyses, 1958-2005. Updated fromLabitzke (2002).…”