Biomass Burning Effects on Clouds - Georgia Institute of ...
Biomass Burning Effects on Clouds Sara Purdue and Haviland Forrister 1 Introduction Direct effects: biomass burning aerosols absorb light (BC and BrC) and scatter light (OA, sulfate) Semi-direct effects: heating effects of aerosols in and around clouds Cloud burnoff, cloud suppression (and sometimes invigoration) Indirect effects: biomass burning aerosols affecting cloud microphysics Twomey effect: increased cloud droplet number and albedo Albrecht effect: increase in lifetime, suppressing precipitation In turn, clouds remove some biomass burning aerosols through rain Also cloud processing
Limitations of research Meteorology also influences smoke (dilution, transportation, inversions, low pressure regions accumulate aerosol and preferentially form clouds), confounding the direct smoke-cloud effect Remote sensing can be used to detect smoke and clouds, but with limitations: cloud/smoke detections not as good over water and ice 2 3 CCN and IN Properties 4 Black carbon semi-direct effects on cloud cover Review and synthesis Koch & Del Genio, 2010
Review of studies on semi-direct effect of black carbon on clouds Includes models and measurements Summary of effects of black carbon WARNING: on cloud cover provided by figure to the right REVIEW caveat mentioned by the paper is that their framework should be considered tentative rather than definitive due to differences between model and field studies (altitudes used, model differences, etc.)
PAPER 5 Cloud condensation nucleation activity of biomass burning aerosol Petters, et al. 2009 Looked at the hygroscopicity (HTDMA) and CCN activity (CCN100) of 24 different fuel types Fresh smoke particle size was correlated to the emissions hygroscopicity Smaller particle = lower Hygroscopicity WARNING: Smoke emissions should have 0.1 < <0.4 (little to no size dependence)
LAB STUDY Most of the samples could serve as CCN in vigorous updrafts fuels growing in more saline soils are better CCN (they have more inorganic content) Organics coating soot particles in general only increases CCN activity because of the increase in size 6 Ice nuclei emissions from biomass burning Petters, et al. 2009 21 different fuels (i.e. plants) Out of 72 burns, only 21 produced ice The largest IN fraction was from swamp grass, producing ~1 IN for every 100 particles detected
In general, not good IN (compared to other sources) WARNING: However, this ability exists, meaning biomass burning emissions have even more capability affect cloud LABtoSTUDY formation, beyond CCN activity Emissions that did act as IN tended to have low organic carbon fraction, high water-soluble ion content, and be assoc. with a more flaming fire phase (rather than smoldering which has more OC content) 7 Semi-Direct Effect
8 The effect of smoke, dust, and pollution aerosol on shallow cloud development over the Atlantic Ocean (Kaufman et al, 2005: PNAS) Background: Increased aerosol number: more but smaller cloud droplets In turn: precipitation is suppressed and cloud lifetime increases Absorbing aerosols in the cloud can absorb light and reduce cloud cover WARNING: Data: Terra MODIS data for 3 months from four regions of the Atlantic: marine aerosol, smoke, mineral dust, and pollution aerosols Results:
SATELLITE DATA STUDY Shallow clouds increase from .2-.4 from clean to polluted/smoke/dust Spatial coverage of shallow clouds extend further for smoke/dust than for clean LWC increases for polluted/dust, not for smoke Radiative effect at TOA is -11 W/m2 (66% due to aerosol-induced cloud changes, 33% due to aerosols directly affecting radiative properties) Lowest: dust Highest: pollution Never published in more formal journal because Kaufman died months later TOP: Red: sub-um particles, smoke, pollution, Green: dust and sea salt BOTTOM: Red: shallow clouds, Green:
deep convective clouds, Blue: 9 mixed On smoke suppression of clouds in Amazonia Feingold, et al. 2005 Large eddy simulations to study cloud-smoke interactions and cloud suppression (i.e. semi-indirect effect) The effect of smoke/biomass burning aerosol on clouds is dependent on location of the aerosol layer and temperature of the emissions If smoke is well mixed just below the cloud layer, the uniform heating destabilizes the surrounding atmosphere and can increase convection WARNING: Emission of hotter smoke can cause even stronger convection, and affects the amount and duration of clouds
If smoke is only within the cloud, the heating causes cloud reduction MODELING Cloud fraction significantly reduced when smoke optical depths 0.6 STUDY Consistent with other observational and modeling studies If smoke layer causes atmospheric stabilization, it can reduce the cloud fraction Changes in the cloud fraction and appearance of the cloud layer are in general dependent on the optical properties, amount of, and location of the smoke 10 Aircraft-measured indirect cloud effects from biomass burning smoke in the Arctic and subarctic (Zamora et al, 2016: ACP) Background: Tietze et al, 2011, modeled how smoke reduces cloud droplet radius and enhances cloud albedo in Arctic liquid clouds (ACI = .04 - .11, possible underestimate)
Data: from aircraft campaigns over Arctic and subarctic Subarctic cumulus cloud case study Multi-campaign data assessment of Arctic/Subarctic clouds Aerosol cloud interactions (ACI) WARNING: How a cloud property (cloud droplet number) changes relative to some aerosol tracer (acetonitrile) .33 indicates all smoke aerosol nucleate cloud droplets FIELD STUDY Discoveries: Smoke-affected cloud droplets were 40-60% smaller than background clouds: would inhibit precipitation and increase cloud lifetime ACI = .16 (multi-campaign)
ACI =.05 (case study with low LWC and high aerosol), more aerosol = more smoke CCN, so greater water vapor competition, decreasing cloud droplet activation and, thus, ACI 11 Indirect Effects 12 Influence of biomass burning on CCN number and hygroscopicity during summertime in the eastern Mediterranean Bougiatioti, et al. 2016 Fire events increased the number of particles w/ Dp > 100nm by more than 50% Particles 60nm and smaller contained mostly organic compounds (82% mass) and were less CCN-active/had the lowest hygroscopicity Particles 100nm and larger were mostly ammonium sulfate and had much higher hygroscopicities
Hygroscopicity of the events ranged between 0.2-0.3 (attributed to differing chemical composition) Freshly emitted biomass burning organic aerosol (BBOA) had 0.06 BBOA that had been more atmospherically-processed had 0.14 < < 0.17 BB plumes that are newer and relatively unprocessed by the atmosphere are less CCN active WARNING: FIELD STUDY Fresher plume = more organic content = less CCN active 13 Effects of biomass burning on climate, accounting for heat and moisture fluxes, black and brown carbon, and cloud absorption effects (Jacobson, 2014: JGR) Goal: to investigate effects of open biomass burning on climate
and pollution Considers: gases and aerosols (BC, BrC, tar balls, reflective particles), cloud absorption effects, aerosol semidirect and indirect effects on clouds Results: WARNING: 20 year simulations show net global warming of .4 K: 32% caused by cloud absorption effects, 7% by anthropogenic heat fluxes Cloud optical depth decreased by open biomass burning Direct aerosol cooling and indirect effects = outweighed by cloud absorption effects, semidirect effects, and anthropogenic heat and moisture fluxes Particle burn-off of clouds (caused by BC) may be a major underrecognized source of global warming (cloud depletion = surface warming)
MODELING STUDY 14 Clouds Affecting BB Aerosol 15 Size-dependent wet removal of BC in Canadian biomass burning plumes (Taylor et al, 2014: ACP) Background: Wet deposition is the dominant removal mechanism for BC Nevertheless: few case studies in ambient environments exist In biomass burning plumes, hydrophobic BC is coated in (relatively more) hydrophilic organic material within hours after emission
WARNING: Data: BORTAS-B aircraft campaign, BC size distributions + coating properties Results: FIELD STUDY Plumes passing through precipitating clouds (Plume 3) showed reductions in BC number & mass BC particles with large coatings were preferentially removed; organic material coatings removed 16 Summary Biomass burning aerosol has different effects on clouds depending on
the circumstances of the aerosol i.e. plume height, temperature, organic content, extent of atmos. aging, etc. Biomass burning aerosols can: Increase CCN/droplet numbers and thereby increase cloud spatial extent and lifetime Invigorate convection Suppress cloud formation or cause cloud burn off In turn, clouds can affect biomass burning aerosol emissions through wet deposition and cloud processing 17 Useful papers to read Biomass burning effect on cloud dynamics: Earle et al., 2011; Jouan et al., 2012; Lance et al., 2011; Lindsey and Fromm, 2008; Rosenfeld et al., 2007; Tietze et al., 2011 Biomass burning effect on precipitation and regional heating: Kay et
al., 2008; Kay and Gettelman, 2009; Lubin and Vogelmann, 2006; Vavrus et al., 2010 18 References Bougiatioti, A., S. Bezantakos, I. Stavroulas, N. Kalivitis, P. Kokkalis, G. Biskos, N. Mihalopoulos, A. Papayannis, and A. Nenes. "Influence of Biomass Burning on CCN Number and Hygroscopicity during Summertime in the Eastern Mediterranean." Atmospheric Chemistry and Physics Discussions Atmos. Chem. Phys. Discuss. 15.15 (2015): 21539-1582. Feingold, Graham. "On Smoke Suppression of Clouds in Amazonia." Geophys. Res. Lett. Geophysical Research Letters 32.2 (2005): n. pag. Jacobson, Mark Z. "Effects of Biomass Burning on Climate, Accounting for Heat and Moisture Fluxes, Black and Brown Carbon, and Cloud Absorption Effects." Journal of Geophysical Research: Atmospheres J. Geophys. Res. Atmos. 119.14 (2014): 8980-9002. Kaufman, Y. J., I. Koren, L. A. Remer, D. Rosenfeld, and Y. Rudich. "The Effect of Smoke, Dust, and Pollution Aerosol on Shallow Cloud Development over the Atlantic Ocean." Proceedings of the National Academy of Sciences 102.32 (2005): 11207-1212. Koch, D., and A. D. Del Genio. "Black Carbon Semi-direct Effects on Cloud Cover: Review and Synthesis." Atmospheric Chemistry and Physics Atmos. Chem. Phys. 10.16 (2010): 7685-696. Petters, Markus D., Christian M. Carrico, Sonia M. Kreidenweis, Anthony J. Prenni, Paul J. Demott, Jeffrey L. Collett, and Hans Moosmller. "Cloud Condensation Nucleation Activity of Biomass Burning Aerosol." J. Geophys. Res. Journal of Geophysical Research 114.D22 (2009): n.
pag. Petters, Markus D., Matthew T. Parsons, Anthony J. Prenni, Paul J. Demott, Sonia M. Kreidenweis, Christian M. Carrico, Amy P. Sullivan, Gavin R. Mcmeeking, Ezra Levin, Cyle E. Wold, Jeffrey L. Collett, and Hans Moosmller. "Ice Nuclei Emissions from Biomass Burning." J. Geophys. Res. Journal of Geophysical Research 114.D7 (2009): n. pag. Taylor, J. W., J. D. Allan, G. Allen, H. Coe, P. I. Williams, M. J. Flynn, M. Le Breton, J. B. A. Muller, C. J. Percival, D. Oram, G. Forster, J. D. Lee, A. R. Rickard, and P. I. Palmer. "Size-dependent Wet Removal of Black Carbon in Canadian Biomass Burning Plumes." Atmospheric Chemistry and Physics Discussions Atmos. Chem. Phys. Discuss. 14.13 (2014): 19469-9513. Zamora, L. M., R. A. Kahn, M. J. Cubison, G. S. Diskin, J. L. Jimenez, Y. Kondo, G. M. Mcfarquhar, A. Nenes, K. L. Thornhill, A. Wisthaler, A. Zelenyuk, and L. D. Ziemba. "Aircraft-measured Indirect Cloud Effects from Biomass Burning Smoke in the Arctic and Subarctic." Atmospheric Chemistry and Physics Discussions Atmos. Chem. Phys. Discuss. 15.16 (2015): 22823-2887. 19
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