Peculiar behavior of solar polar fields during solar cycles 21-23: Correlation with meridional flow speed

Bisoi Susanta Kumar, bisoi.susanta@gmail.com, Physical Research Laboratory, Ahmedabad, India
Padmanabhan Janardhan, jerry@prl.res.in, Physical Research Laboratory, Ahmedabad, India

Abstract
We have examined solar polar magnetic fields during the solar cycles 21-23 using available ground based NSO/Kitt Peak synoptic magnetograms and high resolution synoptic magnetograms from the space borne MDI instrument on-board SoHO. We find from both the NSO/Kitt Peak and SoHO/MDI data that the absolute value of the polar field in the high latitude (780-900) region shows a significant drop starting around 1995-1996 to the maximum of the solar cycle 23. In addition, it has been noticed that the long term changes in the absolute value of the polar field at higher latitudes are well correlated with changes in surface meridional flow speed that have been reported for the solar cycle 23. The implications of this abnormal behaviour of the solar polar field in influencing the prolonged solar minimum will also be discussed.