Abstract


  CORRELATION BETWEEN DECAY RATE OF SOLAR CYCLE AND ITS STRENGTH

  G. Hazra, Indian Institute of Science, Bangalore, ghazra@physics.iisc.ernet.in
  B. Karak, Nordita, Sweden, bbkarak@nordita.org
  D. Banerjee, Indian Institute of Astrophysics, dipu@iiap.res.in

So far people have studied the ascending phase of the solar cycle
i.e, the correlation of the rising time and rising rate with the
peak amplitude of the solar cycle (Waldmeir effect). But there is
no consensus about the descending phase of the solar cycle. We
find a strong correlation between the decay rate of the cycle and
its peak amplitude within a cycle. We also get a strong
correlation between a particular cycle decay rate at late phase
and the subsequent cycle peak amplitude which is certainly a good
precursor for prediction of next cycle.Unfortunately there is no
significant correlation between decay time and the strength of the
cycle. From two dimensional kinematic flux transport dynamo model
we are able to explain all the observed correlation. By
introducing fluctuation in Babcock-Leighton mechanism
and in meridional circulation we get the observed correlation
between decay rate and peak amplitude of the same solar cycle. In
case of fluctuation only in Babcock-Leighton mechanism we are not
able to get the strong correlation between the decay rate at late
phase and the peak amplitude of the next cycle but giving
fluctuation in meridional circulation we get the correlation.
Hence information regarding the meridional circulation in decay
phase is very important for determining the next cycle strength.
We also explore the importance of the meridional circulation in
determining the rising and decaying phase of the solar cycle.