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Update on Cycle 24 Giuliana de Toma collaborators: Gary Chapman, Angie Cookson, Dora Preminger

Update on Cycle 24 Giuliana de Toma collaborators: Gary Chapman, Angie Cookson, Dora Preminger data sources: CSUN/SFO, USAF/SOON, McMath , SOHO/MDI, SDO/AIA SPD 2013 Press Conference. Solar Cycle 24 is different from recent cycles. cycle 21. cycle 22. USAF/NOAA data.

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Update on Cycle 24 Giuliana de Toma collaborators: Gary Chapman, Angie Cookson, Dora Preminger

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  1. Update on Cycle 24 Giuliana de Toma collaborators: Gary Chapman, Angie Cookson, Dora Preminger data sources: CSUN/SFO, USAF/SOON, McMath, SOHO/MDI, SDO/AIA SPD 2013 Press Conference

  2. Solar Cycle 24 is different from recent cycles cycle 21 cycle 22 USAF/NOAA data l follows longest/deepest minimum in 100 years l weakest cycle of the space age l interesting N/S asymmetry (also seen at the poles) Mar 15 2013 SDO/HMI Magnetogram

  3. The differences started in the cycle 23 l north/south asymmetry started in 2005 USAF/NOAA data current spot latitude N = 14deg S = -18deg ~ 2-year time lag The two hemispheres have been out of phase for an unusually long time South activity has increased recently

  4. The differences started in cycle 23 lsignificant decrease of very large spots in cycle 23 SDO/AIA May 11 2012 ~1400

  5. The differences started in cycle 23 lsignificant decrease of very large spots in cycle 23 AIA May 11 2012 ~1400 lspots of all sizes have decreased in cycle 24, especially the large ones

  6. We had small cycles before and the Sun did not go into a Maunder Minimum There were large spots on the Sun before the Maunder Minimum Heveliusdrawing in 1644 (one year before the Maunder Minimum started) We still do not know how and why the Maunder Minimum started

  7. Sunspots are not fainter l spots have the expected brightness for a given area sunspots are not fainter there are just fewer of them… …which is normal for weak cycles this is why weak cycles are weak! San Fernando Observatory/CFDT1 cycle 22 cycle 23 SFO/CFDT1 1986-present longest record of full-disk photometric measurements

  8. McMath-Pierce spot observations….. …. a lively debate brightness increase magnetic field decline if trend continues almost no spots in cycle 25 !! Livingston, Penn, & Svalgaard 2012 but is this trend real? spot brightness magnetic field Courtesy of L. Svalgaard

  9. McMath-Pierce spot observations….. …. a lively debate brightness increase magnetic field decline San Fernando Observatory/CFDT1 San Fernando Observatory/CFDT2 SOHO/MDI find spot brightness stable in time CFDT1 spot brightness

  10. another explanation for this trend McMath-Pierce dataset is not homogeneous - fewer data early on - no small spots included in early data this introduces a bias no trend in the most recent data that do not include small spots magnetic field spot brightness

  11. another explanation for this trend McMath-Pierce dataset is not homogeneous - fewer data early on - no small spots included in early data this introduces a bias no trend in recent data that include small spots CFDT1: all spots spot brightness

  12. another explanation for this trend McMath-Pierce dataset is not homogeneous - fewer data early on - no small spots included in early data this introduces a bias The trend is not caused by a real change in the Sun but by selection effects CFDT1: with small spots removed in early years spot brightness

  13. There is one instrument that can resolve the ongoing controversy: MLSO/PSPT 1” spatial resolution 0.1% photometric precision 1998-present most accurate record of spots and faculae Collaboration with Gary Chapman (CSUN/SFO) & Mark Rast (CU/LASP) Stay tuned for more news on this! Blue cont. 409.4nm Mauna Loa Solar Observatory

  14. AIA Aug 27 2012 McMP restored image 0.2” AIA full res 0.6” AIA reduced to 2.4” CFDT1 5.0” CFDT1 low spatial resolution but 1% photometric precision

  15. M. Rempel (ApJLett 2012)proposed the non-appearance of the high-latitude branch was be due to a change in the differential rotation profile (caused by the decrease in cycle amplitude) Strong cycles have more rigid differential rotation (magnetic tension tends to reduce rotation shear) Weak cycles rotate more differentially, i.e. poles slow down If a mean differential rotation profile is subtracted the polarward branch is hidden If 3.5-year rotational Mean is subtracted polarward branch reappears! R. Howe et al. (ApJ 2013)

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