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Ulrike Langematz, Sophie Oberländer and Markus Kunze

Workshop on "Recent variability of the solar spectral irradiance and its impact on climate modelling”, Berlin, 15.5.2012. The effects of different solar irradiance datasets on stratospheric heating rates and temperatures. Ulrike Langematz, Sophie Oberländer and Markus Kunze

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Ulrike Langematz, Sophie Oberländer and Markus Kunze

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  1. Workshop on "Recent variability of the solar spectral irradiance and its impact on climate modelling”, Berlin, 15.5.2012 The effects of different solar irradiance datasets on stratospheric heating rates and temperatures Ulrike Langematz, Sophie Oberländer and Markus Kunze Institut für Meteorologie, Freie Universität Berlin, Germany

  2. >50% in 121,6 nm (Lyman-α) 5-12% in 175-240 nm 3-5% in 240-260 nm • Largest solar cyclevariations in shortwavelengths – uptoseveraltensofpercent in theultraviolet (UV) spectralrange 11-year solar max minus min 0.1 % change in TSI Lean et al., 1997

  3. Simulation ofthestratospheric solar signalrequires … A) spectrally resolved short-wave radiation scheme Heating rate differences solar max-min Solar only O3 only Solar + O3 (Figure 17, fromForster et al., 2011) • SPARC (Stratospheric Processes and their Role in Climate) CCMVal (Chemistry-Climate Model Validation Activity), Chapter 3 (Radiation)

  4. Simulation ofthestratospheric solar signalrequires … B) spectrally resolved solar fluxes at TOA • Spectral solar fluxes need to be prescribed at top of a GCM or CCM • Standard data set: NRLSSI (Lean, 2000; Lean et al., 2005) • Several new spectral solar irradiance data sets from different measurement platforms exist. • Towhichextentisthesimulated solar signalaffectedbytheprescribed solar fluxesatthe top oftheatmosphere?

  5. Outline • NRLSSI: Standard spectralirradiancedataset • Alternative irradiancedatasets • Effectsofirradiancedatasets on shortwaveheatingandtemperature • Solar signalfrom SIM dataset • Uncertaintyfactors

  6. NRLSSI: Standard spectralirradiancedataset • First dailyspectral solar fluxdatasetfromNaval Research Laboratory, Washington D.C. • Based on empirical model adjustedtomeasurementsfrom • TIMED/SEE (ThermosphereIonosphereMesosphereEnergeticsand Dynamics - Solar EUV Experiment), • SOLSTICE (Solar Stellar IrradianceComparison Experiment) on board UARS (UpperAtmosphere Research Satellite), • completedwithSOLSPEC (Solar SpectralIrradianceMeasurements) on ISS • Most widelyuseddataset • Input for SPARC CCMValclimatescenariosimulations Shortwave Heating Rates in K/day from FUBRad* scheme with NRLSSI data 15 Jan • Maximum heating (~14 K/day) atsummer stratopause (~1 hPa) * Nissen et al., 2007 (Lean, 2000; Lean et al., 2005)

  7. Alternative Irradiance Data Sets I • NRLSSI • Lean, 2000; Lean et al., 2005 • Naval Research Laboratory, Washington D.C. • TIMED/SEE (Thermosphere Ionosphere Mesosphere Energetics and Dynamics - Solar EUV Experiment), SOLSTICE (Solar Stellar Irradiance Comparison Experiment) on board UARS, completed with SOLSPEC (Solar Spectral Irradiance Measurements) • Empirical model • Spectral range: 0 - 3000 nm • Sampling: 1-5 nm • MPS • Krivova et al., 2009, 2011 • MPl für Sonnensystem-forschung, Katlenburg-L. • KPNSO (Kitt Peak National Solar Observatory) magnetograms and SOHO (Solar and Heliospheric Observatory) MDI (Michelson Doppler Imager) images • SATIRE model • Spectralrange: 115 - 160000 nm • Sampling: 1 nm • IUP • Pagaran et al., 2009 • Institut für Umweltphysik, Universität Bremen • SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Chartography) on ENVISAT (Environmental Satellite) • Empirical SCIA proxy model • Wavelength range: 230 – 1750 nm • Sampling: 1 nm

  8. Differences in incomingspectral solar flux • 10 – 20% differencesbetweendatasets in multi-annualmean (1978-2005) in ultraviolet (UV), lessthan 5% in visible (VIS) andinfrared (IR) Pagaran et al., 2011 (Fig. 16 and 17 from Pagaran et al., 2011)

  9. Differences in incomingspectral solar flux integrated to 49 spectral intervals of FUBRad SW CCM radiation scheme TOA solar flux in the Hartley and Huggins bands from IUP, NRLSSI and MPS data at solar minimum, September 1986. • Slightlyhigherincomingfluxes in theHartleybandsforthe IUP dataset • Largestincomingfluxesforthe MPS dataset in mainpartsofthe Huggins bands, relevant forozoneabsorption Central wavelengths of FUBRad spectral intervals [nm]

  10. Effectsof different spectralinputdata on radiativeheating I • Zhong et al., 2008: • Two different solar irradiance spectra in line-by-line radiative transfer code • Spectral data from a theoretical spectral line model (Kurucz spectrum) • NRLSSI data • Heating rates in 200-320nm region (ozone Hartley band) for mid-latitude summer atmosphere • Thick: line-by-line model • Thin: broad-band model • Significant differences of up to 1.1 K/day in shortwave (SW) heating rates between spectra (Figure 2 from Zhong et al., 2008)

  11. Effectsofirradiancedatasets on shortwaveheatingandtemperature II • Changes in SW heatingrates • offlinecalculationswithFUBRadshortwaveradiationparameterisation(Nissen et al., 2007)‏ • highresolution CCM SW radiationscheme • 49 spectralintervals: 121.56 -683nm • 15thJanuaryconditionsfor solar zenith angle and orbital parameters • mean O3-climatology (forJanuary)‏ • Changes in temperaturesandcirculation • GCM-typeexperimentswiththeChemistry-Climate Model EMAC (ECHAM/MESSyAtmospheric Chemistry) (Jöckel et al., 2006)‏in EMAC-FUBconfiguration • FUBRadincluded • horizontal resolution: T42 • 39 levels (upto 0.01hPa)‏ • Januaryconditionsforzenith angle and orbital parameters • mean O3-climatology (forJanuary) • 11-Year Solar Cycle number 22: • Solar minimum: September 1986 • Solar maximum: November 1989

  12. SW heating rate differences for solar minimum [K/day] Global mean • Largestheatingratesfor MPS datasetaround 1 – 10 hPa (Huggins bands) • Slightlyhighervaluesfor IUP datasetaround 0.1 – 1 hPa (Hartleybands)‏ • MPS datasetproducesupto 5% higher SW heatingratesthan NRLSSI in global mean (Oberländer et al., 2012, GRL)

  13. Temperature signal – MPS minus NRLSSI Solar Minimum 11-Year Solar Cycle Differences • Significantly warmer stratospherefor MPS data • Impact ofenhanced solar fluxes in MPS datadirectlyreflected in temperaturechanges • Nosignificanteffect on solar temperaturesignal • Large dynamicalvariability in winter hemisphere (Oberländer et al., 2012, GRL)

  14. 11-Year solar cycle signal SW heating rate differences [K/day], (Cycle 22: Max: Nov 1989; Min: Sep 1986) • NRLSSI • ‚reference‘ data set • 15th January conditions • Stratospheric solar signalupto 0.2K/dayatthesummer stratopause (~50km)↔ Hartley/Huggins bands (O3) • Strong increase in heatingrates in uppermesosphere↔ Lyman-α-line (O2) (Oberländer et al., 2012, GRL)

  15. 11-Year solar cycle signal: Differences between data sets Global mean • MPS • Strongest solar signal (maxto min) • 0.03 K/dayhigherthan NRLSSI in global mean; upto 0.05 K/dayatsummer stratopause • IUP(/MPS) • 20-40% higher global mean solar heatingsignal in lowerandmiddlestratosphere • 10-20% higherforupper strato-sphereandmesosphere (Oberländer et al., 2012, GRL)

  16. Temperature signal – MPS minus NRLSSI Solar Minimum 11-Year Solar Cycle Differences • Significantly warmer stratospherefor MPS data • Impact ofenhanced solar fluxes in MPS datadirectlyreflected in temperaturechanges • Nosignificanteffect on solar temperaturesignal • Large dynamicalvariability in winter hemisphere (Oberländer et al., 2012, GRL)

  17. Solar signal from SIM data set Differences in spectral irradiance:April 2004 minus November 2007 • SIM data • Harder et al., 2009 • SIM (Spectral Irradiance Monitor) on board SORCE (Solar Radiation and Climate Experiment) • Available wavelength range:115-2412 nm • Sampling: 1-34 nm • Available since April 2004 • Up to six times larger changes in UV than NRLSSI from 2004 to 2007 • Variations in the visible (VIS) and near-infrared (NIR) out of phase to changes in TSI and UV with increasing irradiance towards the minimum of solar cycle 23 (Figure 1 from Haigh et al., 2010)

  18. Differences in incomingspectral solar flux (Figure 18 from Pagaran et al., 2011) • SIM data show larger SSI changes • SIM datachanges out-of-phase in VIS comparedto SCIA, SATIRE and NRLSSI • SIM and SCIA proxy changes out-of-phase in NIR for decending solar cycle 23 in contrast to NRLSSI and SATIRE (Pagaran et al., 2011)

  19. Solar Signal from SIM-data – modelling studies at FUB • Prescribed solar flux: mean (May 2004) to minimum phase (Nov 2007) of SC 23 • Modelling setup as before for NRLSSI, IUP, MPS (January conditions, O3 fixed) • Wavelengths < 200nm from SOLSTICE SIM-NRLSSI SW heating rate differences [K/day] at solar minimum • SIM: lower absolute irradiance→ weakerheating in UV bands (upto 0.5 K/dayatsummer polar stratopause, 0.3 K/day in global mean) • SIM: slightlyhigher VIS heatingat solar min (Oberländer et al., 2012, GRL)

  20. Temperature signal – SIM minus NRLSSI Solar Minimum 2007 May 2004 minus November 2007 • Significantly cooler stratosphereandmesosphere in summerfor SIM data due toweaker UV-heating • Significantly warmer summerupperstratosphere in 2004 comparedto 2007 for SIM thanfor NRLSSI data • Negative contribution from VIS flux more than compensated

  21. Solar cycle signal difference SIM  NRLSSI SW heating rates [K/day], May 2004 minus November 2007 • SIM solar signal exceeds NRLSSI by 0.28 K/day at summer stratopause(0.18 K/day in global mean) • SIM produces lower VIS heating for 2004 (solar mean) compared to 2007 (solar minimum), opposite to NRLSSI data (Oberländer et al., 2012, GRL)

  22. Temperature signal – SIM minus NRLSSI Solar Minimum 2007 May 2004 minus November 2007 • Significantly cooler stratosphereandmesosphere in summerfor SIM data due toweaker UV-heating • Significantlystrongerwarming in summerupperstratosphere in 2004 comparedto 2007 for SIM thanfor NRLSSI data • Negative contribution from VIS flux more than compensated

  23. Solar Signal from SIM Data Set – Haigh et al., 2010 December 2004 minus 2007 ΔO3 ΔT 0.3 K NRLSSI • Haigh et al., 2010: • 2D CTM • SIM dataproduceslower O3 above 45 km in 2004 • Very different temperaturestructurecomparedto NRLSSI 1.6 K SIM (Fig. 2 (left) and Supp. Fig. 1 (right), from Haigh et al., 2010)

  24. Integrating spectral flux data sets into spectral radiation codes • Spectral flux data sets have individual spectral resolution. • SW radiation parameterization have individual spectral resolution. Spectral flux data need to be integrated to spectral intervals of SW radiation codes. 2 examples:

  25. 1. Effect of increased spectral resolution in SW radiation code FUBRad: Increase of spectral resolution in Chappuis band from 1 to 57 bands Global mean SW heating rate differences, Nov. 2007 NRLSSI  SIM 106 FUBRad bands 49 FUBRad bands VIS: NRLSSI > SIM VIS: SIM > NRLSSI

  26. 2. Effect of integration method • Comparison of two integration procedures to calculate spectrally integrated solar fluxes for SW radiation code form solar flux input data: • int_tabulated (idl) • bin_trapez SIM data

  27. SW heating rates for different integration methods UV + Chappuis bands Chappuis bands • Int_tab (idl) produceswrongintegratedfluxesforinputdatasetswithinsufficientspectralresolution

  28. 11-year solar signal [K/day] for different integration methods and spectral resolutions • Solar signalis not stronglyaffected due tothedominanceofthe UV. • Work in progress

  29. Thankyouforyourattention!

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