Mark Weber Joseph Pagaran Stefan Noël Klaus Bramstedt and John P Burrows weberunibremende TOSCA Workshop Berlin 1416 April 2012 Motivation x SCIAMACHY observes SSI in UV ID: 552379
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Slide1
SCIAMACHY solar irradiances during solar cycle 23 and beyond
Mark Weber, Joseph Pagaran, Stefan Noël, Klaus Bramstedt, and John P. Burrowsweber@uni-bremen.de
TOSCA Workshop, Berlin, 14-16 April 2012Slide2
Motivation
xSCIAMACHY observes SSI in UV/vis/
near
-IR
solar
irradiance changes in the optical range and (near) UVrelevant for TSI composition (near UV and vis)atmospheric heating rates (uv)Challenges: above 300 nm solar cycle variability is below 1%Optical degradation affects long-term stability of UV SSI Atmospheric and climate impact requires knowlege of spectral solar variability (particularly in theUV)
Grey et al., 2010
continuous
SCIA spectral rangeSlide3
Topics
ENVISAT/SCIAMACHY mission Solar irradiance observationsComparisons with other SSI dataSCIA proxy modelDegradation correctionSlide4
SCIAMACHY
Launch date: February 28, 2002
Polar, sun-synchronous orbit
Descending node: 10:00 LST
Altitude: 800 (783) km
Features:UV/Vis/NIR grating spectrometers: 220 - 2380 nmModerate spectral resolution: 0.2 – 1.5 nmMeasurement Geometries:
SCIAMACHY =
SC
anning
I
maging
A
bsorption
spectro
M
eter
for Atmospheric
CH
artograp
YSlide5
ENVISAT mission status
SCIAMACHY instrument: was healthy, no large data gaps (2002-2012)lost complete communication with ENVISAT on Easter Sunday (April 8th)ESA declared mission end (May 10th)attempts to re-establish contact will continue until end of June /chances are slim
Causes of failure:
loss of the power
regulator
blocking irreversibly telemetry and telecommandshort circuit, triggering a 'safe mode' (kind of shutdown) with subsequent platform anomaly (orientation change)TIRA radar image of ENVISAT (image courtesy Spiegel Online News, April 14, 2012)Photo from PLEIADES (April 15, 2012)Slide6
SCIAMACHY data products
ozone
chemistry
(
nadir/limb/occult)NO2, O3, OClO, BrO, H2O, aerosolgreenhouse gases (nadir)CH4, CO, CO2air pollution/biogenic (nadir)NO2, O3, BrO, IO, H2CO, glyoxal, SO2, H2OOther:Limb: PSC, NLC/PMC, OH* /mesopause T, mesospheric metals
Nadir: pytoplanctons/ocean colour, clouds, surface reflectance, mesospheric
metals, thermospheric NO
spectral solar irradiance (SSI)Slide7
Solar irradiance measurements by SCIAMACHY
Continuous coverage: 230-1700 nm
Spectral resolution: < 1.5 nm
Spectrometer design: double
monochromator
(predisperser prism and gratings in each channel) Reticon linear diode array detectorPagaran et al., 2011aSlide8
Solar irradiance measurements by SCIAMACHY
Daily full solar disc measurements using diffuserRadiometrically
calibrated
before
launchDegradation correction using several optical paths (combination of mirrors and/or diffuser, lamp sources)So far assumes constant irradianceonly suitable for atmospheric applicationsnew degradation corrections are in preparation (see later)Challenges: instrument and ENVISAT platform anomalies maintenances
Pagaran
et al., 2011a
H
2
OSlide9
SCIAMACHY irradiance
comparisons: VIS/NIR Direct comparisons to SOLSPEC/ATLAS3:SCIA agreement to
within
3% in
the
visible and 5% in near IR wrt to other dataover several solar rotationsrelative accuracy ~0.1%!Pagaran et al., 2011a0.2%March 2004Slide10
SCIAMACHY SSI comparisons
: UVComparison of satellite data to Hall-Anderson spectra in the UV SCIA data: low SNR below 240 nmoptical degradation in the UV: ~-15%Correction possible by using internal white lamp sources (WLS)Agreement within 3%However: data is over corrected since WLS
also degrades with time
March 2004
w. WLS
w/o WLSSlide11
Solar proxies
from SCIAMACHY: Mg II indexMg II core-to-wing ratio near 280 nm
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 sensorsused for UV SSI reconstruction and calibration correctionsIs the solar cycle 24 minimum (~2009) lower than prior minima?thermospheric contraction (unusually low neutral density) due to below normal solar activity? (
Emmert et al. 2010, 2011, Solomon et al. 2011)Slide12
SCIAMACHY solar proxy
modelSCIAMACHY proxy modelParameterization of SCIAMACHY SSI changes in terms of scaled solar proxies, here Mg II index (faculae brightening) and photometric sunspot index PSI (sunspot darlening, Balmceda et al. 2009)
allows reconstruction of solar cycle change in SSI
assumes that magnetic surface activity are responsible for irradiance variations (
Fligge
et al., 2000)assumes that solar rotation changes scale up to solar cycle like the proxiessimilar approach: Lean et al., 1997, 2000SCIAMACHY SSI at a reference dateMg II indexPSI index
piecewise polynomials (degradation,
anomaly corrections)
Scaling
parameters
d
erived
from
several
solar
rotations
Mg II
index
PSI
index
Pagaran
et al
.,
2009Slide13
Halloween 2003 solar storm
Irradiance change during Halloween 2003 solar stormLowest PSI value
since
thirty yearsSCIA proxy model separates faculae and sunspot contributionsTSI reduction (-0.4%) about four time higher magnitude than change during solar cycle (~0.1%)dark facula near 1500 nm detected by SCIAMACHY, but is underestimated (see also Unruh et al. 2008)
TSI ~ -0.4%
Pagaran
et al
.,
2009Slide14
SCIA proxy in solar cycle 23
Irradiance change during solar cycle 23 (1996 to 2002)Below 400 nm faculae brightening dominating, with non-neglible contribution from sunspot blocking in the near UV (>300 nm)dark faculae near 1400-1600 nm
Pagaran
et al
., 2011bSlide15
Error estimates for SCIA proxy
Error estimate from the proxy fit to observationsOther systematic errors difficult to assess and are unknownSolar cycle changes in the visible/NIR are statistically insignificant except for 1400-1600 nm (dark faculae)
Pagaran
et al
., 2011bSlide16
Comparisons over several solar cycles
Observations:Some issues in the late 1980 with the de Land UV composite (related to N9/N11 SBUV2 data) in the late 1980s (see also Lockwood et al., 2011)
Larger SIM trend in the UV in SC 23
Models
SATIRE SC variations are bit larger than NRLSSI & SCIA proxy
Lower variability in SIP/Solar2000 (Tobiska et al.)
Pagaran
et al., 2011bSlide17
Comparisons: SSI solar
cycle changes Comparisons of SSI changes
during
part
of descending phases of SC 21-23SCIA proxy model (Pagaran et al., 2009, 2011b)NRLSSI model (Lean 2000)SATIRE model (Krivova et al. 2009)Deland & Cebula (2008) UV compositeSIM/SORCE and SUSIM observationsSIM changes during SC 23 four times larger than the models and doubled the changes of SUSIM and UV composite during SC 22challenges the validity of models assuming solar surface
magnetic activity as a primary source of SSI changes
large impact
on atmospheric heating
rates (Cahalan
et al. 2010,
Haigh
et al. 2010, Oberländer et al., 2012)
and
mesospheric
ozone
(Merkel et al., 2011)
Pagaran
et al
., 2011bSlide18
Summary & conclusions
Spectral solar irradiance from
SCIAMACHY:
Daily
irradiance
and Mg II measurements since 2002-2012SCIA proxy model for extrapolating SSI from solar rotations to solar cycle (SC)Not reproducing SC changes seen with SIMchallenges the validity of proxy
based and empirical models assuming
magnetic surface
activity as
primary source
of
SSI
variations
Clear
need
for
continued
spectral
solar
measurements
Issues
:
long
-term
stability
SC
changes
above
300
nm
are
well
below
1%!
Other solar
related
SCIA
studies
:
27-day solar
signature
in
stratospheric
ozone
(
Dikty
et al., 2010)
and
polar
mesospheric
clouds
/NLCs (Robert et al., 2009)
NH polar
ozone
losses
in
connection
with
QBO
and
solar
activity
(
Sonkaew
et al., 2011)
Solar
proton
related
mesopsheric
ozone
loss
(Rohen et al., 2005)Slide19
300-400 nm
Outlook
Goal:
derivation of SC 23 (24) trends directly from SCIA SSI (w/o proxies)
t
est if SSI UV changes scale from rotational to SC time scale in a different way than the Mg II index (and SCIA proxy)This requires the application of suitable degradation corrections to SCIA SSI:Exploit the different rate of optical degradation in the different optical paths Main cause of degradation: contaminants on mirror & diffuser surfaces (azimuth and elevation scanner) Slide20
Degradation correction: contamination model
A
optical
degradation
model has been developed that fits contamination thicknesses as a function of time to the various optical surfaces Promising resultsBut: this model assumes no natural variability of SSI
Need to improve upon separation
of instrumental and
natural
effects on SSI changes
in
the
contamination
model
Detector heat up
(ice removal on
NIR detectors) Slide21
Further work
Improving optical degradation model for SCIAMACHY derive SSI trends independent of proxiesCombine GOME1 (1995-2011) and GOME-2 (2007-present) SSI data to extend the SCIAMACHY SSI recordChannel 1-4 of the GOMEs (240-800 nm) similar to SCIAMACHY in terms of spectral resolutionSlide22
Publications
Oberländer, S., U. Langematz, K. Matthes, M.
Kunze
, A.
Kubin
, J. Harder, N. A. Krivova, S. K. Solanki, J. Pagaran, and M. Weber, The Influence of spectral solar irradiance data on stratospheric heating rates during the 11 year solar cycle, Geophys. Res. Lett., 39, L01801, doi:10.1029/2011GL049539, 2012.Pagaran, J., M. Weber, J. P. Burrows, Solar variability from 240 to 1750 nm in terms of faculae brightening and sunspot darkening from SCIAMACHY, Astrophys. J., 700, 1884-1895 , 2009.Pagaran, J., J. Harder, M. Weber, L. Floyd, and J. P. Burrows, Intercomparison of SCIAMACHY and SIM vis-IR irradiance over several solar rotational timescales, Astron. Astrophys., 528, A67, doi:10.1051/0004-6361/201015632, 2011.Pagaran, J., M. Weber, M.
DeLand, L. Floyd, J. P. Burrows,Solar spectral irradiance variations in 240-1600 nm during the recent solar cycles 21-23, Sol. Phys., 272, 159-188, doi:10.1007/s11207-011-9808-4, 2011
.
Pagaran, J. A.,
Solar spectral irradiance variability from SCIAMACHY on daily to several decades timescales, Ph.D.
thesis
, University of Bremen, 2012
.
Weber, M., J.
Pagaran
, S.
Dikty
, C. von
Savigny
, J. P. Burrows, M.
DeLand
, L. E. Floyd, J. W. Harder, M. G.
Mlynczak
, H. Schmidt,
Investigation of solar irradiance variations and their impact on middle atmospheric ozone
, Chapter 3, in: Climate And Weather of the Sun-Earth System (CAWSES): Highlights from a priority program, ed. F.-J.
Lübken
, to be published by Springer, Dordrecht, The Netherlands, 2012. Slide23
a
dditional slidesSlide24
solar- earth
atmosphere couplingSolar influence on atmosphere via radiation & charged particles
Impacts
chemistr
y
and dynamics (transport/circulation)courtesy Langematz
solar
irradiance
charged particles
(e,p)
NH
S
H
49 km
Rohen et al. 2005Slide25
Long-term trends in stratospheric
O3x
Adapted from
Steinbrecht
et al., Ozone and temperature trends in the upper stratosphere at five stations of the Network for the Detection of Atmospheric Composition Change, Int. J. Rem. Sens. [2009]Slide26
27 day
signature in SCIAMACHY stratospheric ozoneDifferent frequency
analyses
of
ozoneCWT, FFT, cross-correlationmax. cross-correlation during SC is 0.38, weaker than in prior solar cycles (see also Fioletov, 2009)27d signal 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)
b
lue: ozone
black
: Mg II
index
Dikty
et al. 2010bSlide27
NH polar
chemical ozone loss and QBOSCIAMACHY observation during descending
phase
of
SC23 (mostly close to solar min conditions)Arctic winters with high PSC rates and high ozone loss during QBO west phase (in most cases) Camp & Tung, 2007 Sonkaew et al., 2011
10-50 hPa polar temperature change in Feb-Mar
warm
cold
warm
warm
W
Arctic
ozone
hole 2010/11