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Time-series analysis of supergranule characterstics at solar minimum
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Pesnell, W. Dean Williams, Peter E. |
| Copyright Year | 2013 |
| Description | Sixty days of Doppler images from the Solar and Heliospheric Observatory (SOHO) / Michelson Doppler Imager (MDI) investigation during the 1996 and 2008 solar minima have been analyzed to show that certain supergranule characteristics (size, size range, and horizontal velocity) exhibit fluctuations of three to five days. Cross-correlating parameters showed a good, positive correlation between supergranulation size and size range, and a moderate, negative correlation between size range and velocity. The size and velocity do exhibit a moderate, negative correlation, but with a small time lag (less than 12 hours). Supergranule sizes during five days of co-temporal data from MDI and the Solar Dynamics Observatory (SDO) / Helioseismic Magnetic Imager (HMI) exhibit similar fluctuations with a high level of correlation between them. This verifies the solar origin of the fluctuations, which cannot be caused by instrumental artifacts according to these observations. Similar fluctuations are also observed in data simulations that model the evolution of the MDI Doppler pattern over a 60-day period. Correlations between the supergranule size and size range time-series derived from the simulated data are similar to those seen in MDI data. A simple toy-model using cumulative, uncorrelated exponential growth and decay patterns at random emergence times produces a time-series similar to the data simulations. The qualitative similarities between the simulated and the observed time-series suggest that the fluctuations arise from stochastic processes occurring within the solar convection zone. This behavior, propagating to surface manifestations of supergranulation, may assist our understanding of magnetic-field-line advection, evolution, and interaction. |
| File Size | 2210292 |
| Page Count | 13 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20150008400 |
| Archival Resource Key | ark:/13960/t8md3xm03 |
| Language | English |
| Publisher Date | 2013-08-28 |
| Access Restriction | Open |
| Subject Keyword | Dopplergrams Solar Dynamo Solar Minimum Sun: Supergranulation Helioseismology Sdo/hmi Sun: Photosphere Solar Cycle Soho/mdi Sun: Convection Correlation Size Distribution Image Processing Time Series Analysis Stochastic Processes Solar Activity Effects Soho Mission Data Processing Computerized Simulation Doppler Effect Solar Cycles Time Lag Analogies Solar Granulation Convection Cells Mathematical Models Magnetic Fields Solar Observatories Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
