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G. de Toma (LASP/CU), O.~R. White (HAO/NCAR), G.~A. Chapman, S.~R. Walton (SFO,CSUN), K.~L. Harvey (SPRC)
This paper focuses on the rising phase of solar cycle 23 from the time of solar minimum in 1996 to the present high activity level. A number of observations indicate that cycle 23 maximum is now close, and maybe is already in the maximum phase. They include the distribution of coronal streamers, the presence of long--lived solar coronal holes at low latitudes, the latitudinal distribution of sunspot regions, and the unipolar magnetic fields in the polar regions.
Most of the activity indices, i.e. sunspot number, sunspot area, photospheric magnetic flux, 10.7\,cm radio flux, and UV irradiances, indicate this cycle as a relatively weak cycle as compared to cycles 21 and 22. In particular, observations at San Fernando Observatory of sunspot and facular area are a factor of two or more lower than in solar cycle 22. This is consistent with the lower magnetic flux measured at NSO/KP and UV irradiance measurements, but not with total solar irradiance measurements. We analyze ground--based and space observations to give a comprehensive picture of the evolution of the current cycle and compare it to the solar cycle 22.
The author(s) of this abstract have provided an email address for comments about the abstract: detoma@lasp.colorado.edu