David Hofmanns Pioneering Observations of Stratospheric Volcanic - - PowerPoint PPT Presentation

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David Hofmanns Pioneering Observations of Stratospheric Volcanic Aerosols Alan Robock Department of Environmental Sciences Rutgers University, New Brunswick, New Jersey USA robock@envsci.rutgers.edu http://envsci.rutgers.edu/~robock Dave

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Alan Robock

Department of Environmental Sciences Rutgers University, New Brunswick, New Jersey USA

robock@envsci.rutgers.edu

http://envsci.rutgers.edu/~robock

David Hofmann’s Pioneering Observations of Stratospheric Volcanic Aerosols

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Alan Robock Department of Environmental Sciences

Dave Hofmann’s contributions related to the effects of volcanic eruptions

  • balloon observations of stratospheric aerosols
  • lidar observations of stratospheric aerosols
  • bservations of polar stratospheric clouds
  • bservations of ozone
  • effects of volcanic eruptions on carbon cycle
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Alan Robock Department of Environmental Sciences

I am not an observationalist. But once I got to participate in an

  • bservation

program, helping

  • bserve ozone and

aerosols at McMurdo, Antarctica in spring 2004. Jennifer Mercer and Terry Deshler Dave Hofmann

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Alan Robock Department of Environmental Sciences

Hofmann (1987), Rev. Geophys.

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Alan Robock Department of Environmental Sciences E x p l

  • s

i v e

N E T C O O L I N G

Stratospheric aerosols (Lifetime (Lifetime ≈ 1-3 years) 1-3 years) Ash Effects

  • n cirrus

clouds absorption (IR) IR Heating emission emission IR Cooling More Downward IR Flux Less Upward IR Flux forward scatter Enhanced Diffuse Flux Reduced Direct Flux Less Total Solar Flux

Heterogeneous → Less O3 depletion Solar Heating

H2 S SO2

NET HEATING

Tropospheric aerosols (Lifetime (Lifetime ≈ 1-3 weeks 1-3 weeks) Q u i e s c e n t SO2 → H2 SO4 → H2 SO4 CO2 H2 O backscatter absorption (near IR) Solar Heating More Reflected Solar Flux Indirect Effects

  • n Clouds

Robock (2000), Rev. Geophys.

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Alan Robock Department of Environmental Sciences

  • Mt. Erebus, Sept. 22, 2004
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Alan Robock Department of Environmental Sciences

  • Mt. Erebus, Oct. 3, 2004
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Alan Robock Department of Environmental Sciences

Robock (1983)

SAGE II, III SME

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Alan Robock Department of Environmental Sciences

Hofmann (1987), Rev. Geophys. In discussing lidar data ...

Need for in situ observations

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Alan Robock Department of Environmental Sciences

Robock (1983)

SAGE II, III SME

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Alan Robock Department of Environmental Sciences

Linnea Avallone Jennifer Mercer Roberto Morbidini

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Alan Robock Department of Environmental Sciences

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Alan Robock Department of Environmental Sciences

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Alan Robock Department of Environmental Sciences

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Alan Robock Department of Environmental Sciences

Robock (1983)

SAGE II, III SME

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Alan Robock Department of Environmental Sciences

Francesco Cairo and Roberto Morbidini

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Alan Robock Department of Environmental Sciences

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Alan Robock Department of Environmental Sciences

SKYHI 4-ensemble mean Calculated from Stenchikov et al. (1998) data set

Ramachandran et al. (2000)

Stratospheric Aerosol Distribution

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Alan Robock Department of Environmental Sciences

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Alan Robock Department of Environmental Sciences

Third Assessment Report of the IPCC (2001)

  • Fig. 12-6 (from Free and Robock, 1999)

Volcanic forcing needed to explain climate change of past 150 years: Energy-balance climate model simulations

Volcanic and Solar Forcing Volcanic, Solar, and Anthropogenic Forcing

Climate sensitivity 3°C for doubled CO2 1.5°C for doubled CO2 Instrumental observations

xxxxx

Proxy observations

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Alan Robock Department of Environmental Sciences

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Alan Robock Department of Environmental Sciences

Principal investigator: Thomas Conway, NOAA CMDL http://www.cmdl.noaa.gov/ccgg

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Alan Robock Department of Environmental Sciences

  • Changes in emissions
  • Land use changes
  • Unusual atmospheric temperatures or precipitation

(e.g., drought)

  • El Niño and La Niña episodes (affecting ocean sources

and sinks as well as remote effects on land)

  • Volcanic eruptions through effects on diffuse

radiation Possible causes of interannual CO2 variations

Hofmann (2004)

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Alan Robock Department of Environmental Sciences

Pinatubo El Chichón Agung

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Alan Robock Department of Environmental Sciences

Diffuse Radiation from Pinatubo Makes a White Sky

Photographs by Alan Robock

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Alan Robock Department of Environmental Sciences

Robock (2000), Dutton and Bodhaine (2001)

+ 140 W m-2

  • 175 W m-2
  • 34 %
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Alan Robock Department of Environmental Sciences

Nevada Solar One 64 MW Seville, Spain Solar Tower 11 MW

http://www.electronichealing.co.uk/articles/solar_power_tower_spain.htm http://judykitsune.wordpress.com/2007/09/12/solar-seville/

Solar steam generators requiring direct solar

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Alan Robock Department of Environmental Sciences

Science and Engineering Visualization Challenge

  • Sept. 12, 2003 Science

FIRST PLACE Mongolian Frost Rings Dee Breger Magnification: 35× Sample courtesy of

  • G. Jacoby

Krakatau?

535 A.D. 536 A.D. 537 A.D. 538 A.D.

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Alan Robock Department of Environmental Sciences

The increased diffuse radiation allows plants to photosynthesize more of the time, increasing the CO2 sink (Cohan et al., 2002; Gu et al., 2002, 2003; Farquhar and Roderick, 2003). In fact, Gu et al. (2003) actually measured this effect in trees following the 1991 Pinatubo eruption.

Diffuse Radiation Effect

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Alan Robock Department of Environmental Sciences

Volcano Year of Eruption VEI d.v.i/Emax IVI Latitude Laki craters [Lakagigar], Iceland 1783 4 2300 0.19

H

Unknown 1809 6 2000 0.25

L

Tambora, Sumbawa, Indonesia 1815 7 3000 0.5

L

Cosiguina, Nicaragua 1835 5 4000 0.11

L

Askja, Iceland 1875 5 1000 0.01*

H

Krakatau, Indonesia 1883 6 1000 0.12

L

Okataina [Tarawera], North Island, New Zealand 1886 5 800 0.04

L

Santa Maria, Guatemala 1902 6 600 0.05

L

Ksudach, Kamchatka, Russia 1907 5 500 0.02

H

Novarupta [Katmai], Alaska, United States 1912 6 500 0.15

H

Agung, Bali, Indonesia 1963 4 800 0.06

L

  • Mt. St. Helens, Washington, United States

1980 5 500

H

El Chichón, Chiapas, Mexico 1982 5 800 0.06

L

  • Mt. Pinatubo, Luzon, Philippines

1991 6 1000 —

L

Volcanic eruptions of the past 250 years

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Alan Robock Department of Environmental Sciences

Volcano Year of Eruption VEI d.v.i/Emax IVI Latitude Laki craters [Lakagigar], Iceland 1783 4 2300 0.19

H

Unknown 1809 6 2000 0.25

L

Tambora, Sumbawa, Indonesia 1815 7 3000 0.5

L

Cosiguina, Nicaragua 1835 5 4000 0.11

L

Askja, Iceland 1875 5 1000 0.01*

H

Krakatau, Indonesia 1883 6 1000 0.12

L

Okataina [Tarawera], North Island, New Zealand 1886 5 800 0.04

L

Santa Maria, Guatemala 1902 6 600 0.05

L

Ksudach, Kamchatka, Russia 1907 5 500 0.02

H

Novarupta [Katmai], Alaska, United States 1912 6 500 0.15

H

Agung, Bali, Indonesia 1963 4 800 0.06

L

  • Mt. St. Helens, Washington, United States

1980 5 500

H

El Chichón, Chiapas, Mexico 1982 5 800 0.06

L

  • Mt. Pinatubo, Luzon, Philippines

1991 6 1000 —

L

Volcanic eruptions of the past 250 years

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Alan Robock Department of Environmental Sciences

Northern Hemisphere Temperature Anomalies (°C)

  • 0.7
  • 0.6
  • 0.5
  • 0.4
  • 0.3
  • 0.2
  • 0.1

0.1 0.2 0.3 0.4 0.5 1750 1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980

Year NH Temp. Anomaly (°C)

All Data No Dendro Dendro Only

Reconstruction from Mann et al. (1998)

Krakatau Tambora Unknown

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Alan Robock Department of Environmental Sciences

Conclusions

The effect of enhanced diffuse radiation and less direct radiation after volcanic eruptions on tree growth may bias interpretation of tree rings response following eruptions as being solely records of temperature. When proxy records of Northern Hemisphere climate change are corrected for the diffuse effect, there is no impact on climate change for time scales longer than 20

  • years. However, it appears that there was a

hemispheric cooling of about 0.6°C for a decade following the unknown volcanic eruption of 1809 and Tambora in 1815, and a cooling of 0.3°C for several years following the Krakatau eruption of 1883.

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Alan Robock Department of Environmental Sciences

Are volcanic eruptions an innocuous example that can be used to demonstrate the safety

  • f geoengineering?

No:

  • ozone depletion
  • reduction of precipitation, particularly the

Asian and African summer monsoon, threatening the food supply of billions

  • reduction of direct radiation for solar power
  • no blue skies (but nice sunsets)
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Alan Robock Department of Environmental Sciences

London Sunset After Krakatau 4:40 p.m., Nov. 26, 1883 Watercolor by William Ascroft

Figure from Symons (1888)