!1 Recent anthropogenic increases in SO2 from Asia have minimal impact on stratospheric aerosol Ryan R. Neely III (NCAR/ASP), O. Brian Toon, Susan Solomon, Karen H. Rosenlof, John S Daniel, J. English, J.-P. Vernier Adapted from Neely, R. R., III et al. (2013), Recent anthropogenic increases in SO2 from Asia have minimal impact on stratospheric aerosol, Geophys. Res. Lett, doi:10.1002/grl.50263.
!2 Variability In Global Stratospheric Aerosol L12807 VERNIER ET AL.: VOLCANIC INFLUENCE AERO STRATO L12807 VERNIER ET AL.: VOLCANIC INFLUENCE AERO STRATO L12807 Figure 3. Monthly mean stratospheric 525 nm Aerosol Optical Depth (AOD) evolution between 20 30 km since 2000 from SAGE II (black diamonds), CALIPSO (blue triangles), GOMOS (red stars); (top) 50 N 20 N, (middle) 20 N 20 S and (bottom) 20 S 50 S. Linear Geophys. fits over the Res. all period Lett are 38, plotted L12807 in green. (2011). The rate of increase in stratospheric AOD Adapted from Vernier, J. P. et al. Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade.
!3 Does it matter? What is causing it? L12807 VERNIER ET AL.: VOLCANIC INFLUENCE AERO STRATO L12807 VERNIER ET AL.: VOLCANIC INFLUENCE AERO STRATO L12807 Figure 3. Monthly mean stratospheric 525 nm Aerosol Optical Depth (AOD) evolution between 20 30 km since 2000 from SAGE II (black diamonds), CALIPSO (blue triangles), GOMOS (red stars); (top) 50 N 20 N, (middle) 20 N 20 S and (bottom) 20 S 50 S. Linear Geophys. fits over the Res. all period Lett are 38, plotted L12807 in green. (2011). The rate of increase in stratospheric AOD Adapted from Vernier, J. P. et al. Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade.
!4 Do small changes in stratospheric aerosol impact climate? 2.0 Total Radiative Forcing GISS + no strat. aerosols after 2000 W/m 2 1.5 1.0 "Background" No strat. aerosols Satellite Projections 0.5 El Chichon Pinatubo GISS 0.0 1980 1990 2000 2010 2020 Adapted from Solomon et al. (2011), The Persistently Variable Background Stratospheric Aerosol Layer and Global Climate Change, Science.
Variability in stratospheric aerosol impacts global radiative forcing!5 2.0 Total Radiative Forcing GISS + no strat. aerosols after 2000 W/m 2 1.5 1.0 "Background" No strat. aerosols Satellite Projections 0.5 El Chichon Pinatubo GISS 0.0 1980 1990 2000 2010 2020 Greenhouse gas forcing increased continuously throughout period. Adapted from Solomon et al. (2011), The Persistently Variable Background Stratospheric Aerosol Layer and Global Climate Change, Science.
Variability in stratospheric aerosol impacts global radiative forcing!6 2.0 Total Radiative Forcing GISS + no strat. aerosols after 2000 W/m 2 1.5 1.0 "Background" No strat. aerosols Satellite Projections 0.5 El Chichon Pinatubo GISS 0.0 1980 1990 2000 2010 2020 Adapted from Solomon et al. (2011), The Persistently Variable Background Stratospheric Aerosol Layer and Global Climate Change, Science.
Variability in stratospheric aerosol impacts global radiative forcing!7 2.0 Total Radiative Forcing GISS + no strat. aerosols after 2000 W/m 2 1.5 1.0 "Background" No strat. aerosols Satellite Projections 0.5 El Chichon Pinatubo GISS 0.0 1980 1990 2000 2010 2020 Adapted from Solomon et al. (2011), The Persistently Variable Background Stratospheric Aerosol Layer and Global Climate Change, Science.
Variability in stratospheric aerosol impacts global radiative forcing!8 2.0 Total Radiative Forcing GISS + no strat. aerosols after 2000 W/m 2 1.5 1.0 "Background" No strat. aerosols Satellite Projections 0.5 El Chichon Pinatubo GISS 0.0 1980 1990 2000 2010 2020 Greenhouse gas forcing increased continuously throughout period. Stratospheric aerosol only slowed increase by ~0.2W/m 2 Adapted from Solomon et al. (2011), The Persistently Variable Background Stratospheric Aerosol Layer and Global Climate Change, Science.
Variability in stratospheric aerosol impacts global radiative forcing!9 2.0 Total Radiative Forcing GISS + no strat. aerosols after 2000 W/m 2 1.5 1.0 "Background" No strat. aerosols Satellite Projections 0.5 El Chichon Pinatubo GISS 0.0 1980 1990 2000 2010 2020 What is driving the variability after 2000? Adapted from Solomon et al. (2011), The Persistently Variable Background Stratospheric Aerosol Layer and Global Climate Change, Science.
!10 Two Possible Sources Increase in Asian Anthropogenic emissions (Hofmann et al. 2009) Moderate episodic volcanic injections (Vernier et al. 2011)
!11 Satellite Observations Reveal Volcanic Influence Data from J. P. Vernier
!12 Asian SO 2 Emissions Gg of SO2 50,000 40,000 30,000 20,000 10,000 Emission of SO2 by Region North America Europe FSU East Asia South-East Asia & Aust/NZ India South and Central America Middle East Africa International Shipping Shift from Europe and North America to East Asia 0 1850 1900 1950 2000 Year Adapted from Smith et al. (2011), Anthropogenic sulfur dioxide emissions: 1850 2005, Atmos. Chem. Phys, 11(3), 1101 1116, doi:10.5194/acp-11-1101-2011.
!13 Current observations cannot partition the observed variability to sources Data from J. P. Vernier
!14 The Model: Sulfates: Meteoritic Smoke, Pure Sulfates, Mixed Sulfates Non-Sulfates: Primary Organics (POA), Secondary Organics (SOA), Black Carbon (BC), Wind Blown Dust, Sea Salt CARMA Bins from 0.2 nm to 1100 nm Adapted from English et al. (2011) Adapted from J. English
!15 Model Experiment Setup: SO 2 Schemes Anthropogenic Spin-Up 5 model years 10 model years Volcanic Background (Year 2000) 2000 2010 Model: CESM1(WACCM) coupled to CARMA (bin microphysical model)
!16 Volcanoes drive stratospheric aerosol variability AOD (525 nm) 2 5.5 5 4.5 4 3.5 3 2.5 2 1.5 6 x 10 3 Ul RuRa At Ma Si So Ta Jb ChOkKa Sa 12 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 10 x 10 3 Tropics 20 S to 20 N, 20 km to 30 km Background Background + China and India Background + Volcanoes Observations 30 S to 50 S, 15 km to 30 km Year Recent variability in stratospheric aerosol is mostly due to volcanic eruptions but...influences from anthropogenic emissions may have an impact on the lower troposphere (Neely et al. GRL 2013) Adapted from Neely, R. R., III et al. (2013), Recent anthropogenic increases in SO2 from Asia have minimal impact on stratospheric aerosol, Geophys. Res. Lett, doi:10.1002/grl.50263.
Anthropogenic emissions may have some influence AOD (525 nm) 10 x 10 3 9 8 7 6 5 4 3 Ul RuRa At Ma Si So Ta Jb ChOkKa Sa 2 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 6 x 10 3 30 N to 50 N, 15 km to 30 km Background Background + China and India Background + Volcanoes Observations Northern Midlatitudes 20 S to 20 N, 20 km to 30 km Year!17 3
Anthropogenic emissions may have some influence AOD (525 nm) 10 x 10 3 9 8 7 6 5 4 3 Ul RuRa At Ma Si So Ta Jb ChOkKa Sa 2 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 6 x 10 3 30 N to 50 N, 15 km to 30 km Background Background + China and India Background + Volcanoes Observations Northern Midlatitudes 20 S to 20 N, 20 km to 30 km Year What mechanism leads to this possible enhancement?!18 3
Anthropogenic Influence: The Asian Tropical Aerosol Layer (ATAL) Median 1020 nm Extinction Ratio Observed by SAGE II from 15N to 45N, June thru August!19 Plot adapted from Thomason, L. W. and Vernier, J.-P.: Improved SAGE II cloud/aerosol categorization and observations of the asian tropopause aerosol layer: 1989 2005, Atmos. Chem. Phys. Discuss., 12, 27521-27554, doi:10.5194/acpd-12-27521-2012, 2012.
!20 Asian Anthropogenic Influence on the ATAL Modeled Mean 1020 nm Extinction Ratio from 14ºN to 46ºN, June-August With Global Anthropogenic SO2 Without Chinese and Indian SO2 24 Altitude (km) 22 20 18 16 14 12 150 100 50 0 50 100 150 150 100 50 0 50 100 150 Longitude Longitude Longitude ATAL reduced by ~30%and Background Layer is similar Adapted from: Neely et al., (2014), Regional Contributions of Anthropogenic SO2 Emissions to the Asian Tropopause Aerosol Layer, JGR; Accepted. Extinction Ratio
Conclusions Stratospheric Aerosol Layer Volcanoes Drive Stratospheric Aerosol Variability ATAL SO2 Volcanic Dust SOA POA SO2 OCS Terrestrial SO2 BC Sea Salt Anthropogenic Marine DMS
Conclusions Stratospheric Aerosol Layer Anthropogenic SO2 contributes to the ATAL ATAL SO2 Volcanic Dust SOA POA SO2 OCS Terrestrial SO2 BC Sea Salt Anthropogenic Marine DMS
!23 Questions? Mt. Doom has not contributed to stratospheric aerosol since the Third Age of Middle Earth.