VII/1 Atmospheric transport and chemistry lecture I.Introduction II.Fundamental concepts in atmospheric dynamics: Brewer-Dobson circulation and waves III.Radiative transfer, heating and vertical transport IV.Stratospheric ozone chemistry V.The tropical tropopause VI.Climate gases VII.Solar variability 1 The sun 2 Solar radiation changes, climate & ozone 3 Solar particles and the middle atmosphere

VII/2 Solar irradiance provides energy to the earth system Turco 1997 SW heating UV/Vis/NIR LW cooling Thermal IR

VII/3 Solar irradiance at TOA: near UV/Vis/IR Weber et al., 1998, Weber 1999 Skupin et al., MAR-2004 Ca II HH

VII/4 MgII h and k emission Fraunhofer lines: wing: absorption originating in the photosphere (T~6000K) core: emission, originating in the chromophere/transition region Rottmann et al., 2005

VII/5 Mg II index chromospheric activity index from GOME UV solar activity proxy from core-to-wing ratio of Mg II line  insensitive to optical degradation  linearly correlates well with UV and EUV wavelength variations down to 30 nm (Viereck et al. 2001)

VII/6 Solar UV irradiance variability  Mg II index is a suitable proxy for modelling solar UV and EUV variability (Viereck et al. 2001)  suitable proxy for modelling UV irradiance in climate models and for TSI reconstruction (Fröhlich et al. 2004)

VII/7 Origin of solar irradiance variability variations in received solar UV irradiance are caused by the emergence and decay of active regions as they transit the solar disk. Active regions contain enhanced:  UV brightness (photospheric faculae and chromspheric plages)  localized enhanced magnetic fields Solar UV/vis radiation originates  upper photosphere  chromosphere  transition region Fox, 2004

VII/8 origin of solar irradiance variability H  continuum image (white light) H  line center emission

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VII/10 The magnetic flux at the solar surface also varies quasi-periodically over the 11-year solar cycle. Maximum Maximum Magnetic flux Minimum X-rays The short-wave radiation varies strongly through the activity cycle: from a factor 2 in the UV (<100nm) up to a factor 100 in X-rays. The solar activity cycle

VII/11 solar irradiance variability Largest variations in UV Small variation in visible and NIR (not well known) Lean, 1994

VII/12 UV variation from solar minimum (1996) to maximum (1992) UV variation below 400 nm linearly correlates with MgII index (280 nm) ( Rottmann, 2000 UARS/SOLSTICE

VII/13 Total solar irradiance from space („solar constant“) CGD, NCAR PMOD TSI 0.1% Froehlich, priv. comm.

VII/14 „solar constant“ TSI composite time series from satellite observations Froehlich, priv. communication

VII/15 Modelled TSI contribution UV (<400 nm) contributes 8% to TSI 60% of TSI variability comes from the UV (<400 nm) Lean et al. (1997) estimated abt. 30% contribution from nm varibility to that of TSI (from SOLSTICE observations) Krivova et al nm 50 nm 100 nm ≈60% ≈8%

VII/16 Contribution to TSI variability Lean et al., 1997

VII/17 Solar indices Various solar indices show variation with the 11 year solar cycle and 27 d solar rotation (full disc)  UV brightening competing with sunspot darkening (VIS) Mg index starts in 1978 F10.8 since the early 1900s Sunspots counts since 1700s 122 nm

VII/18 Correlation among indices Sunspot Area 10.7cm Radio Flux GOES X-Ray Flares Climax Cosmic-Ray Flux Geomagnetic aa index Total Irradiance

VII/19 Penetration depth of solar radiation in the atmosphere Liou, 2002 Thuillier et al., 2004

VII/20 Solar influence on climate Climate impact from periodic earth events some evidence for surface T response to solar variability on time scales longer than the 11y cycle (before 1980) solar influence

VII/21 Milankovich cycles: changes in earth orbit parameters ~41ky ~100ky ~19 and 24 ky obliquity excentricity precession Changes in earth parameters  Change in solar insolation

VII/22 Milankovich cycles: climate impact solar insulation anomaly ice volume derivative Wallace & Hobbs 2005

VII/23 Global warming & cooling Lohmann, priv. communication

VII/24 Solar variability and climate: recent past TSI about 0.25% lower than current values during Maunder minimum Sunspot numbers Maunder mínimum Dalton mínimum

VII/25 recent trends solar wave driving BD circulation aerosol ESC Total ozone trends: mid- to high NH latitudes Dhomse et al. (2006)  Increase in NH total ozone since mid nineties  increase in BD circulation strength  rise of solar cycle 23  return to stratospheric aerosol background conditions after Pinatubo eruption

VII/26 Global ozone trends and solar cycle variability WMO 2006, Chapter 3

VII/27 Global ozone trends and solar cycle variability WMO 2006, Chapter 3 Models do not show the double peak (25 and 50 km altitude)  Possible reasons  Data record too short (~2.5 solar cycles)  NOx from particle (electron precipitation) leads to ozone destruction during solar minimum in middle stratosphere -> BUT: equires „huge“ amounts of Nox  Reduced ozone production (less sunlight) in middle stratosphere from enhanced ozone in the upper stratosphere  Interference from QBO and other dynamical effects  Lower stratospheric solar signature are probbaly from dynamical response to solar variability

VII/28 Dynamics Δ Absorption of solar UV-radiation Δ NO x / HO x chemistry Δ UV Δ CP Temperature  Ozone Coupling between solar variability and atmospheric dynamics

VII/29 Solar coupling & planetary waves & polar O3 loss extra solar heating during solar max strengthens subtropical stratopause jet (SJ) in early winter  radiative response Strengthening of westerlies (SJ) means reduced wave progation and reduced BD circulation /warming of tropical tropopause region in early einter  dynamical response Deflection of planetary waves away from subtropics (towards pole) while SJ descends downwards and polewards leading to a waekening weakening of polar night jet (polar vortex) in mid- to late winter warmer polar stratospheric temperatures with reduced polar ozone loss in late winter  chemical response Kodera and Kuroda (2002)

VII/30 U and T response to solar cycle Change in zonal mean wind (u) in m/s and zonal mean temperature (T) in K for a cahnge of 100 sfu (F10.8 units) From solar minimum to maximum ~120 sfu TT uu

VII/31 Solar coupling and QBO extra solar heating during solar max strengthens subtropical stratopause jet (SJ) in early winter  radiative response Strengthening of westerlies (SJ) means reduced wave progation and reduced BD circulation /warming of tropical tropopause region in early einter  dynamical response Deflection of planetary waves away from subtropics (towards pole) while SJ descends downwards and polewards leading to a waekening weakening of polar night jet (polar vortex) in mid- to late winter warmer polar stratospheric temperatures with reduced polar ozone loss in late winter  chemical response Update from Labitzke,1987, and Labitzke and van Loon, 1988 mostly during QBO west phase

VII/32 The Quasi-Biennial Oscillation (QBO) QBO phase defined by zonal mean wind speed (u) in the lower tropical stratosphere (define QBO phase) Downward descent of alternating easterly and westerlies Baldwin et al., 2001 Red: westerlies Blue: easterlies

VII/33 Baldwin, et. al., 2001 Holton-Tan mechanism (1980) QBO: coupling to the extratropics Wind speed differences between QBO east and QBO west phase (40hPa)  Blue: wind speed difference (  u) negative (more easterly)  Red: wind speed difference (  u) positive (more westerly) Holton-Tan mechanism relates mid-latitude planetary wave propagation to QBO  impacting the mean meridonal circulation