polar coronal holes
DESCRIPTION
POLAR CORONAL HOLES. Shea A. Hess Webber W. Dean Pesnell Summer 2010. A Link to Predicting Solar Maximum. Perimeter Tracking Method. SOHO EIT images, 3 wavelengths Picking boundary points along limb Limb brightening Thresholding Tracking points over Harvey Rotation - PowerPoint PPT PresentationTRANSCRIPT
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POLAR CORONAL HOLESA Link to Predicting Solar
Maximum
Shea A. Hess WebberW. Dean PesnellSummer 2010
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Perimeter Tracking Method• SOHO EIT images, 3 wavelengths• Picking boundary points along limb
– Limb brightening– Thresholding
• Tracking points over Harvey Rotation– Differential rotation– Approximately 27 days at equator (Carrington
Rotation)– Approximately 33 days at the poles (Harvey
Rotation)• Trig fit to resolve areas with uncertainties
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304 Å (He II) in red171 Å (Fe XI/X) in blue195 Å (Fe XII) in green
Scale Height:H = kT/Mg
k = Boltzmann constantT = Temperature (in K)M = mean molecular mass of particlesg = acceleration of gravity
Different ions at varying temperatures equate to different heights in the solar atmosphere.
304 Å upper chromosphere171 Å and 195 Å corona
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Perimeter Tracking Method• SOHO EIT images, 3 wavelengths• Picking boundary points along limb
– Limb brightening– Thresholding
• Tracking points over Harvey Rotation– Differential rotation– Approximately 27 days at equator (Carrington
Rotation)– Approximately 33 days at the poles (Harvey
Rotation)• Trig fit to resolve areas with uncertainties
![Page 5: POLAR CORONAL HOLES](https://reader035.vdocuments.us/reader035/viewer/2022062218/568166ee550346895ddb42f0/html5/thumbnails/5.jpg)
![Page 6: POLAR CORONAL HOLES](https://reader035.vdocuments.us/reader035/viewer/2022062218/568166ee550346895ddb42f0/html5/thumbnails/6.jpg)
Perimeter Tracking Method• SOHO EIT images, 3 wavelengths• Picking boundary points along limb
– Limb brightening– Thresholding
• Tracking points over Harvey Rotation– Differential rotation– Approximately 27 days at equator (Carrington
Rotation)– Approximately 33 days at the poles (Harvey
Rotation)• Trig fit to resolve areas with uncertainties
![Page 7: POLAR CORONAL HOLES](https://reader035.vdocuments.us/reader035/viewer/2022062218/568166ee550346895ddb42f0/html5/thumbnails/7.jpg)
Perimeter Tracking Method• SOHO EIT images, 3 wavelengths• Picking boundary points along limb
– Limb brightening– Thresholding
• Tracking points over Harvey Rotation– Differential rotation– Approximately 27 days at equator (Carrington
Rotation)– Approximately 33 days at the poles (Harvey
Rotation)• Trig fit to resolve areas with uncertainties
![Page 8: POLAR CORONAL HOLES](https://reader035.vdocuments.us/reader035/viewer/2022062218/568166ee550346895ddb42f0/html5/thumbnails/8.jpg)
Southern Polar Coronal Hole Average
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Northern Polar Coronal Hole Average
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Updated Data• Threshold adjustment in all wavelengths• Extended data time series from 2007 to 2010• 304 Å comparison with Nishu
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Further Work• Fine-tune thresholds• Adjust programs to run by HR vs. by year• Convert programs to work with SDO data• Do similar image analysis with magnetograms
and compare• Re-address solar B angle periodicity
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AcknowledgmentsW. Dean Pesnell
Nishu KarnaPeter Williams
Mike KirkAlex Young
Most of the Solar Physics scientists…
Background Image: SDO AIA Composite ImageData Images: SOHO EIT Images
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