2022-11-17T14:36:28.000Z 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 Osaka Matsumoto DeRosa(RCO) -> Katsukawa 412 412 null HOP412 02/20 QS, SYN QS, SYN Quiet Sun, Synoptic 19 -21 -884 0 0 2022-11-17T12:11:00.000Z 2022-11-17T12:27:35.000Z -21 -884 Synoptic SOT Latitudinal Scans (updated version of HOP79) Normal map 30 arcsec, Shorter Irradiance: DO NOT MODIFY! Main Objective: To study how small-scale magnetic flux and solar irradiance varies over the sunspot cycle Scientific Justification: 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 inthe 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. We propose to observe a north-to-south latitudinal strip with SOT-SP on a regular basis to better understand the variation of irradiance with rising flux levels in the photosphere. These observations have the potential to reveal new and important aspects of the relation between solar irradiance and magnetic flux emergence over the solar cycle when compared with TSI measurement satellites such as TSIS-1 and TSIS-2. In addition, work by Shiozu and Tsuneta has shown that HOP 79 N-S scan scan data can be used to infer the latitudinal temperature variation between the equator and the poles thus offering constraints on "thermal wind" theories of convection zone rotational profiles. Lites, Centeno, and McIntosh 2014 analyzed the north-to-south latitudinal strip with SOT/SP (HOP79) for the period Nov 2008 to May 2013, the rising phase of Cycle 24. They found that the smallest scale flux did not appear to vary along with the large-scale flux of the cycle, while a polarity transition at the polar region was observed. Further synoptic observations can be used to compare changes in small-scale flux along the meridian for a second solar minimum period, as well as for Cycle 25 which could potentially be stronger than Cycle 24.