V/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.Greenhouse gasses (GHG) and climate VII. Solar (decadal) variability and dynamical coupling

V/2 Climate: energy in the sun-earth system Earth‘s radiation budget Turco 1997 SW heating UV/Vis/NIR LW cooling Thermal IR

V/3 solar and terrestrial radiation Solar irradiance coming from the photospheric layer (Stefan-Boltzmann Law, T sol =5800 K): Radiative power (units: Watt) the solar photosphere: Solar intensity at earth‘s radius: „solar constant“

V/4 solar and terrestrial radiation (II) total solar intensity received on earth surface (  R 2 is only illuminated): Mean radiative flux density on the entire earth surface: radiation budget without atmosphere  net radiative flux density (intensity) at surface  such a radiation budget can be set up at any altitude earth

V/5 Solar Insulation Wallace & Hobbs 2005

V/6 solar and terrestrial radiation at earth‘s surface: Radiative equilibrium at the surface (F=0) thermal IR radiation emitted from surface solar radiation (UV/VIS) reflected back into space (a=0.3 planetary albedo)

V/7 Climate without atmosphere without an atmosphere earth‘s mean surface temperature would be T=255K=- 18°C. Atmosphere is responsible for thermal insulation and a global average surface temperature of T=288K=+15°C. solar radiation is a black body with T=5800K attenuated by a factor of represents 99% of shortwave emission (<4  m) terrestrial radiation is a black body with T=255K and represents 99% of longwave emission (>4  m) shortwave and long wave spectrum on earth‘s surface SW LW

V/8 SW and LW radiation from pole to pole Wallace & Hobbs 2005

V/9 greenhouse gases: IR active gases Hanel et al. 1972

V/10 simple climate model: the atmospheric green house effect Simple model:  atmosphere is approximated as an infinitely thin layer having a temperature of T A. It is transparent to shortwave radiation (UV/vis) but opaque to longwave radiation (IR)  surface has a temperature of T B and reflects 30% (a=0.3) of shortwave radiation back into space (albedo=0.3). Like the atmosphere the surface is completely absorbing longwave radiation and acts like a blackbody with surface temperature T B. radiation budget (energy balance):

V/11 simple climate model: the green house effect T A =255K corresponds to the mean temperature at 5.5 km altitude (~500 hPa). This altitude divides the real atmospheric mass in about two halves. T B =303K=30°C is about 15°C larger than the global mean surface temperature of 288K. The heating of the atmosphere occurs because of IR absorption of H2O, CO2, CH4 etc. However, in a real atmosphere:  Some of the IR region is transparent (atmospheric window)  UV/vis region is not completely transparent mainly due to O3, O2, and H2O absorption  Clouds modify the planetary albedo (a= ) Analogy to a real green house:  glas is 60% transparent to UV/vis radiation but much less transparent to IR  heat-up of the glas house is mainly due to convection (wind protection!). This is the major difference to the real atmosphere

V/12 atmospheric windows atmospheric window(s) greenhouse gases in IR atmospheric windows Turco 1997

V/13 earth energy budget Turco 1997

V/14 climate feedbacks: direct (radiation) and indirect Stratospheric aerosols (major volcanic eruption):  direct effect: changes in albedo (scattering/cooling) and absorption (soot/warming)  Indirect effect: increases amount of CCN, more cloud can form Role of clouds:  Cloud cover changes modify planetary albedo Turco 1997 Chemical feedback  Ozone depletion contrbutes to stratospheric cooling  Warmer troposphere leads to higher water vapor amounts, modifies clouds  Methane oxydation enhances stratospheric H2O (CH4+OH  CH3+H2O), additional IR cooling  Chemical response to temperature changes  circulation changes (transport & chemistry)

V/15 stratospheric aerosol

V/16 Stratospheric aerosol and temperature Impact of El-Chichon and Pinatubo  increase in stratospheric temperatures in the tropics (increase of 100hPa for about 1-2 years  increase in H2O vapor (reduced freeze drying)? anti-correlation between Arctic and tropical LS temperature  aerosol effect on Brewer-Dobson circulation ? Dhomse et al., 2006 Pinatubo El Chichon

V/17 Trends in greenhouse gases (surface): CO2 Note today: [CO2]  382 ppmv [CH4]  1800 ppbv Mouna Loa Hawaii Ahrens 1999

V/18 Trends in greenhouse gases (surface) Note today: [CO2]  370 ppmv [CH4]  1800 ppbv IPCC 2001

V/19 Current trends: CH4 and CO2

V/20 GHG in the past fromice cores Note today: [CO2]  370 ppmv [CH4]  1700 ppbv Age in kyears 0 ky 150 ky

V/21 Surface temperature trend Note: Year 2005 record warm year in NH NASA/GISS

V/22 radiative forcing: greenhouse gases SROC IPCC

V/23 Forcing scenario (future prediction) Turco 1997

V/24 Surface temperatures from the past to the future change in NH surface temperature until 2100  from +1K to +5.5 K dependent on models Mann et al, 1998 Mann et al., 1998: temperature proxy data ECHO-G1: climate model result Cubash

V/25 GHG sources & sink Major CH4 sink: CH4+OH  CH3+H2O CO2 CH4 CFC

V/26 GHG space observation: local sources Green house gases (CH4) and air pollution CO, SO2, NO2 Richter Buchwitz

V/27 Prediction of climate change cooling warming Schmidt, MPI-HH 2xCO2 2xCO2 + GHG

V/28 Prediction of climate change Temperature change from climate model due to doubling CO2 and changes in SST (sea surface temperature) SST changes from a coupled ocean-atmosphere model with a 2xCO2 atmosphere Schmidt, MPI-HH July doubling CO2 only SST change + doubling CO2 July Changes in T  Changing reaction rates & heterogeneous chemistry  Changing atmospheric circulation (transport )

V/29 Ozone and climate change stratospheric cooling leads to larger PSC volumes accumulated over winter Update Rex et al. 2004, Rex et al larger PSC volumes leads to higher observed heterogenous chemical ozone loss in Arctic winters high variability due to transport & chemistry (BD circulation) Arctic CTM model results (solid: 2.5° grid, light: 7.5° grid)

V/30 Current trends in GHG emissions GWP: greenhouse gas warming potential (relative to CO2) „success“ of Montreal protocol and amendments „failure“ of Kyoto protocol