85th AMS Annual Meeting

Tuesday, 11 January 2005
Redefining the solar cycle: an operational perspective
William J. Murtagh, NOAA/NWS/Space Weather Prediction, Boulder, CO
Sunspot measurements are the historical method of characterizing the solar cycle. We are currently in the waning stages of Solar Cycle 23 and as solar minimum approaches, we expect to see sunspot numbers decline, and the occurrence of significant solar flares and coronal mass ejections to dwindle. This may suggest to some that space weather impacts will be negligible for years to come. But for many organizations affected by space weather, significant impacts occur long after the sunspot maximum. In fact, large sunspot maxima do not necessarily translate to the most geoeffective cycles. From an operational impacts perspective, the period of concern is that time when any given system is most impacted by space weather. These periods can occur at very different times than the sunspot maximum. I will highlight this fact that space weather, like tropospheric weather, is seasonal and always present.

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