Curtis Walker – UCAR/SOARS/SUNY OneontaCurtis Walker – UCAR/SOARS/SUNY Oneonta

Scott Sewell – NCAR/HAOScott Sewell – NCAR/HAO

Steve Tomczyk – NCAR/HAOSteve Tomczyk – NCAR/HAO

Sun’s “Atmosphere”Sun’s “Atmosphere” ~10~10⁶ K plasma⁶ K plasma Origin of the Solar Origin of the Solar

WindWind Emits massive Emits massive

quantities of energyquantities of energy Can only be seen Can only be seen

naturally during naturally during total solar eclipsetotal solar eclipse

Total solar eclipse, July 11, 1991, observed at Hawaii.Photo Credit: S. Koutcmy, IAP-CNRS (France)

Instrumentation Instrumentation that produces a that produces a false eclipse of the false eclipse of the sun allowing sun allowing coronal coronal observationobservation

Ground-based Ground-based and satellite-and satellite-based varietiesbased varieties

Zeiss Coronagraph at Lomnicky Peak Observatory in SlovakiaPhoto Credit: Steve Tomczyk

LASCO SatellitePhoto Credit: NASA SOHO

Dark Frame Dark Frame CorrectionsCorrections

Flat Field Flat Field CorrectionsCorrections

Aerosol RemovalAerosol Removal

The white tracks represent aerosol trajectories over ~1s.

One image from time series of 120 images.

Image histogram representing dynamic range of image.

Adjusted image histogram showing saturated pixel spike at 4000 ADU.

A series of 120 images containing A series of 120 images containing atmospheric aerosols were obtained in atmospheric aerosols were obtained in Boulder, CO on June 16, 2010.Boulder, CO on June 16, 2010.

The mean and median images of this time The mean and median images of this time series were calculated.series were calculated.

Time Series Based AlgorithmTime Series Based AlgorithmMean Time Series AlgorithmMean Time Series AlgorithmMedian Time Series AlgorithmMedian Time Series AlgorithmProcessing Time in both cases ~180sProcessing Time in both cases ~180s

Mean image of all 120 images. Note the aerosol streaks near the building and at left.

Median image of all 120 images. Note that the streaks disappear.

Image resulting from replacement of elements from mean image.

Image histogram showing lack of signal above 3000 ADU.

Image resulting from replacement of elements from median image.

Image histogram showing lack of signal above 3000 ADU.

Before Aerosol Removal After Aerosol Removal

We have successfully removed aerosols We have successfully removed aerosols from our images efficiently utilizing a pair of from our images efficiently utilizing a pair of time series based algorithms (mean and time series based algorithms (mean and median).median).

Future work will investigate more subtle Future work will investigate more subtle deviations between using mean and median deviations between using mean and median images (i.e. - streaks in mean image?).images (i.e. - streaks in mean image?).

We will seek to optimize these algorithms to We will seek to optimize these algorithms to allow for real-time processing.allow for real-time processing.

Science Mentor: Scott Science Mentor: Scott SewellSewell

Writing Mentor: Amy Writing Mentor: Amy StevermerStevermer

Community Mentor: Community Mentor: Lance JonesLance Jones

Peer Mentor: Theresa Peer Mentor: Theresa AguilarAguilar

HAO Instrumental HAO Instrumental GroupGroup

UCAR CommunityUCAR Community

This work was performed under the auspices of the Significant Opportunities in Atmospheric Research and Science Program.

Image histogram spike at 4000 ADU is due to aerosol contamination.

Resultant image histogram of Mean Time Series Algorithm. No signal at 4000 ADU.

Pixels were given a Pixels were given a value of 0 or 1 based value of 0 or 1 based on threshold.on threshold.

0 (black) if they were 0 (black) if they were below two standard below two standard deviations above the deviations above the mean (2-sigma).mean (2-sigma).

1 (white) if they were 1 (white) if they were above 2-sigma. above 2-sigma. THESE WERE THE THESE WERE THE AEROSOLS!AEROSOLS!

The white tracks represent aerosol trajectories over ~1s.

Aerosol trajectories fainter, but still present after Mean Time Series Algorithm.

Image from LASCO Satellite on July 6, 2009.

Image from Mauna Loa Solar Observatory in Hawaii on July 15, 1999.