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A new paradigm for supergranulation derived from large-distance time-distance helioseismology: pancakes
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Hanasoge, Shravan M. Duvall, Thomas L. |
| Copyright Year | 2012 |
| Description | With large separations (10-24 deg heliocentric), it has proven possible to cleanly separate the horizontal and vertical components of supergranular flow with time-distance helioseismology. These measurements require very broad filters in the k-$\omega$ power spectrum as apparently supergranulation scatters waves over a large area of the power spectrum. By picking locations of supergranulation as peaks in the horizontal divergence signal derived from f-mode waves, it is possible to simultaneously obtain average properties of supergranules and a high signal/noise ratio by averaging over many cells. By comparing ray-theory forward modeling with HMI measurements, an average supergranule model with a peak upflow of 240 m/s at cell center at a depth of 2.3 Mm and a peak horizontal outflow of 700 m/s at a depth of 1.6 Mm. This upflow is a factor of 20 larger than the measured photospheric upflow. These results may not be consistent with earlier measurements using much shorter separations (<5 deg heliocentric). With a 30 Mm horizontal extent and a few Mm in depth, the cells might be characterized as thick pancakes. |
| File Size | 38393 |
| Page Count | 1 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20120013617 |
| Archival Resource Key | ark:/13960/t87h6km4n |
| Language | English |
| Publisher Date | 2012-08-13 |
| Access Restriction | Open |
| Subject Keyword | Solar Physics Helioseismology Time Dependence Power Spectra Solar Granulation Signal To Noise Ratios Distance Depth Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
