SCIAMACHY solar irradiances during solar cycle 23 and beyon - PowerPoint Presentation

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