2007-11-21T19:56:59.000Z http://sot.lmsal.com Ted Tarbell LMSAL http://lmsal.com 3251 Hanover Rd, O/ADBS, B/252, Palo Alto, CA, 94304 +1-650-424-2400 tarbell@lmsal.com Hinode SOTSP Tohbans: Arikawa Planner: Magara (Bando) Observer: Ishikawa 46 46 null HOP46: Irradiance scan (N-S) Synoptic SOT Irradiance Scans SYN Active Region 9 0 -128 0 0 2007-11-22T22:57:00.000Z 2007-11-22T23:51:35.000Z 0 -128 Synoptic SOT Irradiance Scans Normal map 60 arcsec, Irradiance: DO NOT MODIFY! The total solar irradiance varies by about 0.1% over the course of the solar cycle, primarily due to the influence of magnetic structures such as sunspots and faculae on the photospheric spectral irradiance. Short-term irradiance variation (on the scale of days-to- months) is well understood to be due to the balance of sunspots and facular areas as they cross the disk. However on the decadal scale of the solar cycle, questions remain as to why the irradiance variation can lead and/or lag the active region count over the course of the cycle. Explanations ranging from changes in the solar diameter in response to magnetic flux storage in the convection zone to changes in the surface area of the photosphere due to F-mode modulation have been put forward. Seeing-free observations of both granulation and magnetic flux on a large range of scales are now possible with the SOT SP/FG instrument combination.