Solar Spectral Irradiance:
lyman Alpha,
MagnEsium II, and
Sigma k proxiEs
(SSIAMESE)
Martin Snow & Tom Woods (CU/LASP)
Janet Machol (CU/NOAA/NCEI)
Gary Chapman, Debi Choudhary, & Angie
Cookson (CSUN/SFO)

SSIAMESE Objectives
• Improve the SFO proxies
• Improve the Lyman alpha composite
• Improve the Magnesium II composite

11-12 May 2017

SIST Annual Meeting

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San Fernando Observatory
• Several solar telescopes
with a continuous synoptic
observing campaign
stretching back to the mid
1980’s.
• Calcium II images, used to
create sunspot darkening
and facular excess proxies
using contrast thresholds.
11-12 May 2017

SIST Annual Meeting

2017-04-14 at 19:24:08 U.T.
CFDT1 Ca II K-line (393.4 nm)

3

SFO Proxies
• Telescope move to campus is complete.
– CFDT1 and CFDT2 are operational.
– CFDT3 is under construction

• Work on preparing the indices for
distribution through LISIRD has been
largely put on hold during the move.
• Progress will resume this fall.
11-12 May 2017

SIST Annual Meeting

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Lyman alpha
• Work on updating Lyman alpha
composite has been delayed due to
launch of GOES-16 (Janet).
– GOES-16 will become primary data source
for Lyman alpha composite later this year!

• Work on line profile models continue
– Kretzschmar et al. (in preparation)
– New SUMER observations acquired in April
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SIST Annual Meeting

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SUMER Empirical Model

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SIST Annual Meeting

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Magnesium II
•
•
•
•

GOES-16 EUVS-C
Revision of SOLSTICE algorithm
Revised scaling
Intercomparisons

11-12 May 2017

SIST Annual Meeting

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GOES-16 EUVS-C
•
•
•
•
•
•

First light: January 20, 2017
Spectral resolution: 0.1nm
512-element diode array
3 second cadence
Geostationary (24/7)
SNR > 3000

11-12 May 2017

SIST Annual Meeting

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EUVS-C Algorithm
• Weighted sums produce “core” and
“wing” values
• Masked pixels provide real-time
background

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SIST Annual Meeting

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GOES-16 Time Series

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Comparison to He II

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M-class flares in April

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Lessons from GOES-16
• Original plan was to use Gaussian fits to
cores as was done for SOLSTICE.
• Performance was poor:
– Fits don’t always converge.
– Operational code had trouble keeping up.

• Revised algorithm to use weighted sum
(i.e. mean) for cores as well as wings.
11-12 May 2017

SIST Annual Meeting

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Apply Lessons to SOLSTICE
• Variance of SOLSTICE measurements
during the day larger than EXIS
• 0.1% unc/scan
• New method:
– Combine 24 hours
– Interpolate
– Use EXIS masks

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SIST Annual Meeting

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New algorithm at solar min

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Comparisons….

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Native Scales

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Scale all to N16 in 2005

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Magnesium Mafia
• Data providers should to agree upon a
common scaling, i.e. the “NOAA Scale”
–
–
–
–
–
–

Snow et al. (Colorado) EXIS, SOLSTICE
Weber (Bremen) GOME, SCIAMACHY
Deland (SSAI) OMI, SBUV
Tobiska (SET)
Viereck (NOAA/SWPC)
Morrill, Floyd, several cats, Spiny Norman

11-12 May 2017

SIST Annual Meeting

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SSIAMESE Summary
• SFO Indices work should resume this
fall.
• Lyman alpha composite analysis is
ongoing with three papers in preparation
• Magnesium II:
– New Measurements
– New Algorithms
– New Comparisons
11-12 May 2017

SIST Annual Meeting

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