  We explore subtle variations in disk-integrated measurements spanning
  $\lsim$ 18 years of stellar surface magnetism by using a newly developed
time-frequency gapped wavelet algorithm.
  We present results based on analysis of the Mount Wilson
  Ca II H and K emission fluxes in four, magnetically-active stars (HD 1835
[G2V], 82885 [G8IV-V], 149661 [K0V] and 190007 [K4V]) and sensitivity tests
using artificial data.
  When the wavelet basis is appropriately modified (i.e., when the
time-frequency resolution is optimized), the results are consistent with the
existence of spatially localized and long-lived
  Ca II features (assumed here as activity regions that tend to recur in
narrowly-confined latitude bands), especially in HD 1835 and 82885.
  This interpretation is based on the observed persistence of relatively
localized Ca II wavelet power at a narrow range of rotational time scales,
enduring as long as $\gsim$ 10 years.
