1. Status on SSI and Mg II from GOME/SCIAMACHY/GOME-2
IUP Bremen contribution to
the SOLID project
Mark Weber, Wissam Chehade, Asher Riaz
Universität Bremen
EU SOLID Annual Meeting, Orleans, France, Oct. 2013

2. SSI from SCIAMACHY/GOME/GOME-2 recent work on the Mg II index
Content
SSI from SCIAMACHY/GOME/GOME-2
recent work on the Mg II index
Outlook on future work (e.g. EU SOLID)
SOLID database

3. SCIAMACHY/GOME/GOME-2 SSI
GOME-2A: 2007-present
GOME-2B: 2012-present
Daily full solar disc measurements using a diffuser
Radiometrically calibrated before launch
Challenges:
instrument and platform anomalies
UV radiation damage (deposits of comtaminants on optical surfaces)
SCIAMACHY
GOME/-2
Pagaran et al., 2011a

4. Solar irradiance measurements by SCIAMACHY
Continuous coverage: nm (GOMEs nm)
Spectral resolution:
~1.5 nm @ >1000nm
< 1000 nm
Spectrometer design: double monochromator (predisperser prism and gratings in each channel)
Reticon linear diode array detector
GOME/GOME-2
Pagaran et al., 2011a

5. SCIAMACHY optical throughput monitoring
Ch. 2: nm
SCIA: UV optical degradation weaker than GOME/GOME-2
Icing of NIR detectors /decontamination by detector heating
Ch. 7: μm

6. New degradation correction for SCIAMACHY
From measurements using various solar light and WLS paths in SCIAMACHY and an optical throughput model layer thicknesses of decontaminants on mirror/diffuser surfaces are fitted
ASM mirror
ESM mirror
ESM diffuser
WLS internal mirror
takes into account scan angle dependence
White Light Source

7. Future plans on solar research (beyond SOLID)
Project SCIASOL as part of the BMBF Priority Programme ROMIC (‘Role of the Middle Atmosphere in Climate’)
Degradation correction to SCIAMACHY SSI (improve optical throughput model accounting for natural SSI variability)
Recalibrated SSI datasets from GOME/SCIAMACHY/GOME-2 ( nm)
 Updated datasets for EU SOLID
NOTE: GOME, SCIAMACHY, GOME-2 data in the SOLID database are still uncorrected data!

8. Some hot topics: NIR SSI
NIR SSI lower by 8% (>1600 nm) w.r.t.
ATLAS-3/SIM
 See talk by Bolsee
Bolsee et al., Sol. Phys., revised (under review)

9. Some hot topics: NIR SSI
Models (COSI, SRPM) are between ATLAS-3/SIM and SCIA/SOLAR
Thuillier et al., Sol. Phys., accepted
Solar1/WHI adjusted to ATLAS-3
SCIAMACHY spectrum from the beginning of the mission (2002)/ WLS corrected
 see talk by Thuillier

10. Mg II index from SCIAMACHY/GOME/GOME-2
Mg II core-to-wing ratio near 280 nm
Indicator for chromospheric activity
Correlates well with UV and EUV SSI changes (Deland and Cebula 1993, Viereck et al., 2001)
insensitive to instrumental degradation (to first order) (Heath & Schlesinger 1986)
composites available from multiple sensors (since 1978)
used for UV SSI reconstruction and degradation corrections
GOME
F [mW/m2 nm]
solar max & min
Wavelength (nm)

11. GOME/SCIAMACHY/GOME-2 MgII time series
Classical definition (H&S 1986): GOME-2
High resolution definition (emission core resoved): GOME/SCIA

12. Mg II index timeseries database
Data included in the composite

13. Matching of Mg II indices for creating composites
Scaling by linear regressions in overlapping time periods:
x vs y and y vs x (red) and then taking averages (blue)
Scaling works best if large overlaps exists (e.g. GOME-U/SOLSTICE)
However: GOME quite noisy towards end of its lifetime

14. Corrections for inhomogeneities
SCIAMACHY(2009/01) and GOME-2A (2009/09) affected by decontamination activities (detector heating for additional outgassing)
Composite index:
use N16/SBUV2 as transfer standard across solar minimum
Treat both GOME-2 and SCIA as separate time series before and after decontamination when scaling

15. Updated composite Mg II index
Unusually low activity in SC 24
SC24 solar minimum lower than before?
GOME/SCIA/GOME-2 Mg II indices and composite updated daily
>> Solar Activity

16. Comparison to the new SORCE Mg II index
Snow et al., J. Space Weather Space Clim., submitted
Very good agreement with N16 and SOLSTICE B
Drift in Solstice A (a solar aperture problem)
Solar minimum of SC24 well covered by current Mg II indices, some differences after 2011 (aging problems?, needs to be looked upon again)

17. Long-term stability of Mg II index from a single instrument
Error calculation (very crude): nm

18. Validation of error estimate (GOME-2)
Qualitative good agreement
Simple error model needs:
SNR near 280 nm from preflight conditions
degradation rates (intensity ratios with respect to mission start)

19. Long-term stability of GOME?
Since we roughly average 4 irradiance values (e.g. wing values), we assume ΔW≈ΔI/√4  1/SNR=0.0007/4
Due to advanced degradation larger uncertainties at SC24 minimum (2009)
NOTE: error only accounts for random errors!

20. IUP-UBR contribution to SOLID
main contribution to WP2 (irradiance data exploitation)
Collecting/updating SSI and proxy data  SOLID database (Task 2.1)  see next slides
Update/improve IUP data products (Task 2.1)
Mg II index
Ca II/Mg I/H_alpha,beta,gamma(?),…
Recalibrated GOME/SCIAMACHY/GOME-2A/GOME-2B
assessment of SSI & proxy data  error analysis incl. long-term stability (Task 2.2)
composite SSI & proxy data (mainly UV)  merging, gap filling, and error analyis (Task 2.5)  see talk by Scholl
Recommendations on 1) exisiting SSI data and 2) future SSI missions (Task 2.6)

21. SOLID SSI & Proxy database
Working space database
Original data: ascii, binary, …
“Password protected“
user name: ssi_database
password: EUsolid2013
Public data website:
common data format: netcdf w/ CF convention
additonal data, e.g. image masks
plotting capabilities

22. SSI database structure
e.g. Mg II, Ly-α, radio fluxes
Proxies
reference SSI data e.g. ATLAS-3
SSI time series

24. Appendix

25. SSI database (discussion)
Structure of database
data storage
which data to store
‚reference‘ SSI data (‚single spectra‘, e.g. Hall & Anderson, Kurucz, Nickel & Labs, Shuttle-Atlas‘, rocket data, Wehrli composite)
SSI timeseries (SBUVs, UARS, ENVISAT, SOHO,…)
proxy timeseries (F10.7, Lya, MgII, CaII, PSI, sunpsots,….)
New datasets from/during this project
primary literature to the data (pdf‘s)
Wavelength range of SSI, e.g. > 115 nm, EUV: nm
Split responsibility: EUV: ROB, UV/VIS/NIR: UBre
common file format
web interface to data/visualisation?
digitalisation of data?
Web page (how to present the database/documentation/quality assessment)
Links to other databases (e.g. LASP LISIRD)
Property rights? restricted to the consortium initially
Updates (‚living database‘)
public outreach

26. UV wavelength definitions
ISO standard (ISO-21348):

27. 27 day signature in SCIAMACHY stratospheric ozone
different frequency analyses of ozone
CWT, FFT, cross-correlation
max. cross-correlation during SC is 0.38, weaker than in prior solar cycles (see also Fioletov, 2009)
27d signal in ozone
is varying and vanishes for selected 3-month periods (max correlation r=0.7)
about a factor 2 smaller than observed in other studies and earlier solar cycles (e.g. Gruzdev et al., 2009)
blue: ozone
black: Mg II index
Dikty et al. 2010b

28. SCIA Proxy Model SCIAMACHY proxy model
allows reconstruction of solar cycle change in SSI
assume that magnetic surface activity are responsible for irradiance variations (Fligge et al., 2000)
assume that solar rotation changes scale up to solar cycle scale
Parameterization of SCIAMACHY SSI changes in terms of scaled solar proxies, here Mg II index (faculae brightening) and photometric sunspot index PSI (sunspot darlening)
similar approach: Lean et al., 1997, 2000
SCIAMACHY SSI at a reference date
Mg II index
PSI index
piecewise polynomials
(degradation,
anomaly corrections)
Scaling parameters derived
from several solar rotations
Mg II index
Pagaran et al., 2009
PSI index

29. SSI solar cycle changes
Comparisons of SSI changes during descending phases of SC 21-23
SCIA proxy model (Pagaran et al., 2009,2011b)
NRLSSI model (Lean 2000)
SATIRE model (Krivova et al. 2009)
Deland & Cebula UV composite
SIM/SORCE and SUSIM observations
SIM changes during SC 23 four times larger than the models and doubled the changes of SUSIM and UV composite during SC 22
challenges the validity of models assuming solar surface magnetic activity as a primary source of SSI changes
large impact on atmospheric heating rates (Calahan et al. 2010, Haigh et al. 2010) and mesospheric ozone (Merkel et al., 2011)
2004/01 minus 2007/01 (not a full solar cycle)
Pagaran et al., 2011b
Ermolli et al., 2012

30. x Mg II and Ca II emission Ca II emission core not spectrally resolved
Does Ca II provide additional information (not already contained in MgII)? x

31. SSI timeseries from space
Ermolli et al., 2012
Request for SOLID partners:
Provide a list of SSI and/or proxy data he/she has access to by contacting
useful information: link to data or size of data file(s), data format, primary reference to data (PDF)
Will send out questionnaire for data and provide ftp server for data dumping

32. List of SSI missions (>115 nm)
European missions