Characterization and Direct Radiative Impact of Arctic Aerosols: observed and modeled

Transcription

1 Third Santa Fe Conference on Global and Regional Climate Change Santa Fe, New Mexico, October 31 November 2, 2011 Characterization and Direct Radiative Impact of Arctic Aerosols: observed and modeled R. S. Stone Cooperative Institute for Research in Environmental Sciences University of Colorado-Boulder NOAA Earth System Research Laboratory Global Monitoring Division Transport of aerosols into the Arctic Measurement strategy Results; radiative forcing efficiency The role of black carbon (soot)

2 Acknowledgments: NOAA Global Monitoring Division: E. Dutton, J. Augustine, D. Longenecker, J. Wendell, D. Nelson, B. Andrews, A. Jefferson, J. Ogren, G. Anderson (AFRL); Station technicians Many co-authors (see reference list) Other contributors; noted on slides NOAA Arctic Research Program A. Herber V. Vitale J. Burkhart

3 Source regions of aerosol transported into the Arctic haze dust H Oceanic DMS, sea salts L L smoke volcanoes

4 deposition along path leaves small particles mixing inhibited by inversion Arctic inversion layer pollutants smoke volcanic sea salt sulfate dust Barrow; Oct-May (Tomasi et al. 2011)

5 JOK Institute of Atmospheric Sciences and Climate SOD HRN ALO NYA SUM ALT EUR TIK GAW BRW POLAR-AOD project: characterize the climate-forcing properties of aerosols in polar regions

6 Sun photometry

7 Optical Depth I = I o e - /cosθ o (Beer s Law) TOA; airmass 1 I o Rayleigh O 3 NO 2 L θ o H 2 O I SP

8 Inter Calibration Campaign ~ Oct Izana, Tenerife accuracy: Mean Bias Difference ~ (Mazzola et al., 2011)

9 SWD = DIRECT(θ 0 ) + DIFFUSE DIFFUSE AOD(λ) DIRECT Barrow Observatory

10 NETsw = SWD - SWU Albedo = SWU/SWD SWU Barrow Albedo Rack

11 30 June 2004 Barrow H Brooks Range

12 noon midnight noon midnight Height (Km) Aerosol Optical Depth July 3 July Barrow DOE/ARM MPL 0

13 DARF (or radiative forcing efficiency) is defined as the change in NETsw in response to a unit increase in AOD at 500 nm negative slope => cooling at the surface

14

15 NET shortwave irradiance (W m -2 ) Direct Aerosol Radiative Forcing (over snow at BRW) solar elevation dust haze Smoke ΔNET sw AOD -1 (W m -2 AOD -1 ) Volcanic? (Young et al., 2011) AOD(500 nm)

16 50 G. Anderson (AFRL) B. Andrews observed Closure modeled

17 radiative forcing efficiency (W m -2 AOD -1 ) cooling warming Aerosol radiative forcing in the Arctic TOA 2008 BRW surface 2010 Fourmile Canyon fire ocean tundra sea ice snow surface albedo (adapted from Stone et al., 2008; Fig. 10) Simulations of the direct radiative forcing by boreal smoke for a solar zenith angle of 50 º.

18 Altitude (km) Total Heating Total Heating 3 smoke 2 WARMING 1 0 COOLING below bkg heating AO ~0.1 (adapted from Stone et al., 2008; Fig. 5) Simulations of heating rate profiles for smoke over tundra for a solar zenith angle of 65 º. 6 AOD(500) within the layer Heating Rate (K day -1 ) heating AOD bkg heating AOD ~ heating AOD=.3 heating AOD heating AOD= heating AOD=.35 heating AOD= heating AOD= heating AOD=.72 heating AOD = heating AOD = 1.0 heating AOD =1.1 heating AOD =1

19 semi-direct effect increases atmospheric stability may suppress cloud formation normal cloud formation cloud suppressed soot Temperature (Lindeman, et al. 2011)

20 Fourmile Canyon Fire ~ Boulder, CO 6-7 Sept Radiative forcing efficiency sunset noon see poster

21 Arctic aircraft investigations Longyearbyen, Svalbard - 1 April 2009

22 Sun photometer mated to a Schulz solar tracker; Polar-5 K-H Schulz

23 N36 Polar-5 Flight ~ April 2009

24 Flight provided a 3-D snapshot of Arctic aerosols more than 80,000 spectra were obtained (1 s resolution) Arctic Haze hangs over Svalbard ~ April 2009

25 Arctic Enhancement background haze MLO (3400m) Hawaii

26 26 March, 2009 eruption of Mount Redoubt, (AP photo; A. Grillo) Hofmann et al., 2009 > emissions from China Solomon et al., 2011 > minor volcanoes Globally, stratospheric aerosols have increased in abundance since Volcanic aerosols were lofted at times to over 60,000 ft and carried east and northward into the Arctic

27 Barrow, AK ~ long-term record of AOD(500) FWNIP SP clean background only El Chicon Pinatubo (adapted from Tomasi et al., 2011; in review) upper atmosphere AOD has increased during last decade

28 The role of black carbon (soot) (Shindell and Faluvegi, 2009) suggest: black carbon has contributed ~ ºC to Arctic warming, in part due to Asian emissions (Flanner et al., 2009) suggest: surface darkening caused by particles mixed with snow outweighs the dimming influence of particles in the atmosphere. findings underlie UN recommended mitigation policy

29 Q. Is soot contributing to the rapid decline in Arctic sea ice? A. probably NOT NSIDC data/ucar image

30 2009 Polar-5 SP-2 BC profiles (S-M Li) ARCTAS ~ April 2008 median (smoke) NOAA AGASP Hanson and Novakov, 1989 The atmospheric burden of black carbon has diminished since the mid-1980s NP36 profile background (Warneke et al., 2010) Z A B (Matsui et al., 2011; adapted from Fig. 10b) Barrow, A. Jefferson Alert, S. Sharma Zeppelin, K. Eleftheriadis

31 EBC, ngm Alert Barrow Ny Alasund (S. Sharma, et al., 2006) 2011 update; unpublished Barrow ~ A. Jefferson Zeppelin ~ K. Eleftheriadis Apr 09 Apr Decimal Year

32 Snow surveys

33 International Polar Year survey (Doherty et al., 2010) vs. 60 observations. it is doubtful that BC in Arctic snow has contributed to the rapid decline of Arctic sea ice in recent years.

34 Conclusions: Arctic AOD is highly variable, depending on transport Radiative forcing (direct, indirect and semi-direct) is highly dependent on solar geometry and surface type SW effects (cooling) increase as melt progresses The recent increase in background AOD is attributed to minor volcanoes, possibly coal burning in China [BC] has decreased significantly in the Arctic; thus is an unlikely contributor to the loss of sea ice

35 Doherty, S. J., Warren, S. G., Grenfell, T. C., Clarke, A. D., and Brandt, R. E.: Light-absorbing impurities in Arctic snow, Atmos. Chem. Phys. Discuss., 10, , doi: /acpd , Flanner, M. G., Zender, C. S., Hess, P. G., Mahowald, N. M., Painter, T. H., Ramanathan, V., and Rasch, P. J.: Springtime warming and reduced snow cover from carbonaceous particles, Atmos. Chem. Phys., 9, , doi: /acp , Hansen, A. D. A., and T. Novakov (1989), Aerosol black carbon measurements in the Arctic haze during AGASP II, J. Atmos. Chem., 9, , doi: /bf Hofmann, D., J. Barnes, M. O'Neill, M. Trudeau, and R. Neely (2009), Increase in background stratospheric aerosol observed with lidar at Mauna Loa Observatory and Boulder, Colorado, Geophys. Res. Lett., 36, L15808, doi: /2009gl Lindeman, J., Z. Boybeyi, and I. Gultepe (2011), An examination of the aerosol semi-direct effect for a polluted case of the ISDAC field campaign, J. Geophys. Res., doi: /2011jd015649, in press. Matsui, H., et al. (2011), Seasonal variation of the transport of black carbon aerosol from the Asian continent to the Arctic during the ARCTAS aircraft campaign, J. Geophys. Res., 116, D05202, doi: /2010jd Mazzola, M., et al., Evaluation of sun photometer capabilities for retrievals of aerosol optical depth at high latitudes: The POLAR-AOD intercomparison campaigns, Atmospheric Environment (2011), doi: /j.atmosenv (in press) Sharma, S., E. Andrews, L. A. Barrie, J. A. Ogren, and D. Lavoue (2006), Variations and sources of the equivalent black carbon in the high Arctic revealed by long-term observations at Alert and Barrow: , J. Geophys. Res., 111, D14208, doi: /2005jd Shindell, D., and G. Faluvegi (2009), Climate response to regional radiative forcing during the twentieth century, Nat. Geosci., 2(4), , doi: /ngeo473. Solomon, S., J. S. Daniel, R. R. Neely, J. P. Vernier, E. G. Dutton, and L. W. Thomason (2011), The persistently variable background stratospheric aerosol layer and global climate change, Science,

36 Stone, R. S., G. P. Anderson, E. P. Shettle, E. Andrews, K. Loukachine, E. G. Dutton, C. Schaaf, and M. O. Roman III (2008), Radiative impact of boreal smoke in the Arctic: Observed and modeled, J. Geophys. Res., 113, D14S16, doi: /2007jd Stone, R. S., G. P. Anderson, E. Andrews, E. G. Dutton, E. P. Shettle, and A. Berk (2007), Incursions and radiative impact of Asian dust in northern Alaska, Geophys. Res. Lett., 34, L14815, doi: /2007gl Stone, R. S., J. A. Augustine, E. G. Dutton, N. T. O'Neill, and A. Saha (2011), Empirical determinations of the longwave and shortwave radiative forcing efficiencies of wildfire smoke, J. Geophys. Res., 116, D12207, doi: /2010jd Stone, R. S., et al. (2010), A three-dimensional characterization of Arctic aerosols from airborne Sun photometer observations: PAM-ARCMIP, April 2009, J. Geophys. Res., 115, D13203, doi: /2009jd Stone, R. S., J. R. Key, and E. G. Dutton (1993), Properties and decay of stratospheric aerosols in the Arctic following the 1991 eruptions of Mount Pinatubo, Geophys. Res. Lett., 20(21), , doi: /93gl Tomasi et al., An update of the long-term aerosol optical properties in the polar regions using POLAR-AOD and other measurements performed during the International Polar Year, Atmospheric Environment (2011), (in review). Warneke, C., et al. (2010), An important contribution to springtime Arctic aerosol from biomass burning in Russia, Geophys. Res. Lett., 37, L01801, doi: /2009gl Young, C. L., Sokolik, I. N., and Dufek, J.: Regional radiative impact of volcanic aerosol from the 2009 eruption of Redoubt volcano, Atmos. Chem. Phys. Discuss., 11, , doi: /acpd , 2011.