Mathematics – Logic
Scientific paper
May 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009spd....40.0932g&link_type=abstract
American Astronomical Society, SPD meeting #40, #9.32; Bulletin of the American Astronomical Society, Vol. 41, p.822
Mathematics
Logic
Scientific paper
The solar supergranulation is an elusive, yet well-observed, surface-filling network of roughly polygonal cells made up of horizontally diverging material. Cells have diameters of 30 Mm, flow speeds of 500 m s-1, and lifetimes of 1 day. Theoretical models for the supergranulation abound but can be separated into two classes: convective (Simon and Leighton 1964; van der Borght 1979) and non-convective (Rieutord et al. 2000; Rast 2003b; Rieutord et al. 2008). If supergranulation is convective, then cells should be warmer at their centers than at their borders, on average. However, the sign and magnitude of the supergranular temperature gradient is poorly constrained. The Precision Solar Photometric Telescope (PSPT), operated by the High Altitude Observatory at the Mauna Loa Solar Observatory, off ers 0.1% relative photometric accuracy, good enough to resolve the expected low-amplitude thermal intensity modulation. For this work we have used a library of 3174 PSPT images to measure the mean azimuthally averaged thermal intensity profile in supergranules. Using a morphological algorithm (Berrilli et al. 1998; Rast 2003a), we have produced maps of the chromospheric network present in Ca II K images. After carefully aligning concurrent continuum images with these maps, we find that cell borders are on average 0.30 - 0.25% brighter. This difference, due to the presence of the magnetic network on supergranule borders, is consistent with previous measurements (Lin and Kuhn 1992). Once the magnetic contribution is removed from the intensity signal, we find that cell borders are on average 0.10% dimmer than cell centers. This corresponds to a temperature drop of 1.0K at the borders of supergranules. This measurement is in good agreement with the only other values for this quantity available in the literature (Rast 2003a; Meunier et al. 2007b, 2008).
Goldbaum Nathan Jonathan
Rast Mark P.
No associations
LandOfFree
The Convective Signature of the Solar Supergranulation does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Convective Signature of the Solar Supergranulation, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Convective Signature of the Solar Supergranulation will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1112121