Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Chemistry and Physics Discussions Atmospheric erence in indirect ff -line studies varies ff ects on by de- ) combustion aerosols, ff ff BC/OM) are often emitted together with 2 , respectively, but could be more positive ff ects are much more uncertain, which hin- 2 ff − 19988 19987 2.45 W m − depending on the nucleation capability of hygroscopic and 2 2 − − , and O. Popovicheva 1 ects of hygroscopicity of ff , J. E. Penner 1 ects. Several studies have noted the sensitivity of aerosol forcing to ice nucleation in ff This discussion paper is/has beenand under Physics review (ACP). for Please the refer journal to Atmospheric the Chemistry corresponding final paper in ACP if available. Department of Atmospheric, Oceanic, and Space Sciences, University ofD. Michigan, V. Skobeltsyn Institute of Nuclear Physics, M. V. Lomonosov Moscow State University, e vertical profiles andcan decreasing also surface act radiation. ascreasing Combustion the cloud aerosols droplet nuclei, radius.by causing This greenhouse indirect causes gases. cooling Combustion e which aerosols(IN) counteracts can in the also mixed-phase clouds warming act (e.g., as Cozicet heterogeneous et al., al., ice 2009; 2008), nuclei Penner as et well al., asders in 2009). cirrus Their clouds prediction. ice (Koehler e Duea to small the change abundance in of their fossil ice nucleation fuel ability ( can produce a large di 1 Introduction Soot aerosols produced by fossil(BC) fuel and and organic biomass matter burning (OM). contain both Both black act carbon to absorb solar radiation, thereby changing hygroscopicity (hydrophobic, hydrophilic andto hygroscopic) specify and their ice usedanthropogenic nuclei laboratory forcing abilities. in data mixed-phase The clouds.from new The 0.111 scheme net to results forcing 1.059 in in Wsoot m o significant particles. changes The to totalnew scheme anthropogenic is cloud 0.06 W m forcingif hygroscopic and soot whole-sky particles are forcingwater allowed path with to dominates the nucleate the ice anthropogenic particles. forcing The in change mixed-phase in clouds. liquid Fossil fuel black carbon andsulfate, which organic coats matter the surface ( of theseservational particles studies and show changes that their the hygroscopicity. hygroscopicity Ob- nucleation of ability. soot To address particles this, can we modulate implemented their a ice scheme that uses 3 levels of soot Abstract combustion aerosols on mixed-phase clouds Y. Yun 1 Ann Arbor, MI2 48105, USA Moscow, 119234, Russia Received: 8 July 2012 – Accepted: 30Correspondence July to: 2012 Y. – Yun ([email protected]) Published: 9 August 2012 Published by Copernicus Publications on behalf of the European Geosciences Union. The e Atmos. Chem. Phys. Discuss., 12, 19987–20006,www.atmos-chem-phys-discuss.net/12/19987/2012/ 2012 doi:10.5194/acpd-12-19987-2012 © Author(s) 2012. CC Attribution 3.0 License. 5 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erent ¨ ff archer erentiating ff ects (AIE) do not explic- cient ice nuclei (K ff erent ice nucleation prop- ffi ff BC/OM) (Wang et al., 2009). We ff erentiate their freezing abilities. ) for both coated and uncoated soot ff 1 − erences in the properties of the bare soot ff 19990 19989 ciencies, and develop a method of di erent laboratory studies, and also the applicability ffi ff BC/OM (3-hydrophobic, hydrophilic and hygroscopic) soot ect of adding a soluble coating to soot. One possible reason ff ect of coating on the ability of soot particles to nucleate ice ff ff erences in nucleation is the di ff 80 %. Hydrophobic soot never forms a film, while hydrophilic soot does de- < Popovicheva et al. (2008, 2010) suggested that the hygroscopicity of soot could be We implemented a 3- During the lifetime of soot aerosols in the atmosphere their hygroscopicity can be scheme in place of a single category scheme (1- midity velops a film. Hygroscopic sootet al. develops (2011) several layers identified of thedrophobic threshold water to amount uptake. hydrophilic of Popovicheva to sulfate hygroscopic coatingthresholds soot needed are as to 1 used transform monolayer here. hy- andlink Koehler 3 soot et monolayers. hygroscopicity These al. to (2009) itsfrozen IN performed fractions ability, a based of series on hydrophobic, Popovicheva ofvarious et hydrophilic, experiments conditions, al. and which to (2008, hygroscopic are 2010). also soot The used were here measured to at di 2011) and Koehler ethygroscopicity, and al. ice (2009), nucleation e whichhydrophobic, provide hydrophilic, and a hygroscopic link particles and between their sulfuric ice nucleation acid inquantified coating, models. by the amount of water film extended over the soot surface at relative hu- of the results toa modeling freezing studies. onset Furthermore, condition the (forof example, results 0.1 the % are ice or usually supersaturation 1in expressed % required a as for the numerical activation aerosols), model whichdemonstrated after that are the a not addition typical of directly asoot time comparable soluble particles, step coating to which can of the most alter model 30 the inputitly min. ice studies needed consider nucleation Nevertheless, of (e.g., ability aerosol these Yun of and indirect studies Penner, e 2011). 2012; Lohmann Here and we Hoose, adopt 2009; Storelvmo recent et laboratory al., studies from Popovicheva et al. (2008, 2010, conclusions about the e for the di particles, for example, theof organic sulfuric content, acid porosity, coatinghinders surface the were area, comparability not etc. among quantified The di in amounts most of these laboratory studies. This homogeneous freezing conditions of sulphuric acid. These studies all lead to di saturation respectively. After coating by sulfuric acid, they all nucleated ice close to the ter saturation above theirof the experimental soot detection particle limitparticles concentration, generated (which or from was about a mini-CAST 10 aboutwater l Real saturation, 0.01–0.1 Soot ice % Generator nucleation at could 253 havebut K occurred could and for not 243 both K. coated be Above and distinguishednucleation uncoated from soot of droplet formation. ice Crawford at eta al. 210–235 CAST K (2011) propane examined for burner sulfuric withcoated acid various soot amounts coated particles of soot with organicand particles 30 content. % those They generated organic found with from mass that 80 % un- content freeze and before 90 % water organic saturation, mass content are inactive or freeze at water tures of soot andsoot sulfuric to acid nucleate ice. requiredthe The higher uncoated GSG supersaturation lamp soot than black that usederties, soot of used by with by uncoated Mohler the DeMott et uncoatedet et al., GSG al. al. 2007). soot (1999) (2005) Friedman and being et have al. a very (2011) much di found more no heterogeneous e ice nucleation below wa- DeMott et al. (1999) conducted233 experiments K ice with nucleation on sulfuric lampfound acid black that soot coating at ice 213– varying nucleationperature from when required the zero the soot to particle highestfuric several was acid. supersaturation weight treated However, at with percent. the almostlower approximately It critical one when every was monolayer supersaturation BC tem- of required particles sul- ric for were acid. ice treated Mohler formation with etfrom was a much al. a multilayer equivalent (2005) Graphite coverage Spark investigated of ice Generator sulfu- nucleation (GSG) of at soot 185–240 K, particles and generated found that internal mix- and Penner, 2012). altered through coating by sulfatehave (Zhang et investigated al., the 2008). e Several(DeMott laboratory et experiments al., 1999; Mohler et al., 2005; Friedman et al., 2011; Crawford et al., 2011). mixed-phase clouds (Lohmann and Hoose, 2009; Storelvmo et al., 2011, 2008a; Yun 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C as ◦ BC/OM BC/OM 40 ff ff − ine radiation cient for the, ffl ffi ect of aerosols, ff 3, the particle is < C at water saturation ◦ coat n 40 ≤ − BC/OM aerosol fields, as well ff C) in Koehler et al. (2009). Due to the ◦ 57 3, the particle becomes hygroscopic. The − C for hygroscopic soot. However, the frozen ≥ ◦ ) is calculated and compared with threshold ine model, and is used to calculate the total 19992 19991 40 C or ffl coat coat ◦ − n n 51.5 − BC/OM species prior to coating by sulfate (and water) ine model reads the aerosol and meteorology fields and ff ffl BC/OM categories. Ice nucleation was measured at ff ine radiation model is similar to the 1st indirect e ffl ect of the Bergeron-Findeisen process. 1, the particle remains hydrophobic. If 1 ff < ¨ coat oschl et al., 1998). n ine radiation model of Chen and Penner (2005) was extended to include BC/OM scheme erentiation between hydrophobic, hydrophilic, and hygroscopic ffl BC/OM scheme was implemented into the CAM-IMPACT coupled aerosol ff ff ff ine radiation model. The coupled model (inline simulation) provides the aerosol BC/OM particles are assumed to be hydrophobic. After each time step, the num- ffl ff The PH08 parameterization was modified to treat the nucleation of ice in mixed- The o volume mean diameter of the BC/OMonly particles data in for our polydisperse model particles which at is 180 nm. There are surfaces (P phase clouds by the 3- well as at a colder temperaturecoexistence ( of liquid and ice, watermodel. saturation Therefore, is assumed we in use mixed-phaseto the clouds in adjust frozen our the fraction PH08 measureddrophilic parameterization at soot, in we mixed-phase use the clouds. data For for hydrophobic the and 200 nm hy- particles because this size is close to the values. If moved to the hydrophilic category.size If distributions of theare three assumed fixed (seecondensation Penner of et sulfuric al., acid 1998).(Zhang on The et hydrophobic al., accommodation and 2005), coe hydrophilic while particles that for is hygroscopic set particles to is 0.65, 0.018 similar to sulfuric acid with the added e 2.2 3- The di aerosols is based onted the number of monolayers ofber sulfuric of acid monolayers of coating. sulfate Freshly coating emit- ( process (the conversion ofmodel, liquid due to ice) to was itsno also importance further implemented to processing in radiative the ofprecipitation forcing o ice formation). (Storelvmo particles Therefore, et takes the al.,calculated from place anthropogenic 2008b). the (no However, forcing o sedimentation, in coagulation, mixed-phase or clouds as that in the CAM-IMPACT model (Yun and Penner, 2012). The Bergeron-Findeisen mixed-phase clouds. The ice nucleation scheme in mixed-phase clouds is the same well as aqueous formationAlthough of BC sulfuric and OM acid are inbe treated cloud as internally distinct droplets mixed species (Liu (e.g., in et Wanga the al., two-moment et model, 2005). microphysics they al., scheme The are for 2009). NCAR assumed cloudIn to CAM3 liquid mixed-phase model and was ice clouds, (Wang updated the andtion/condensation/immersion to Penner, Phillips include freezing 2010). et was implemented al.contact (Yun (2008) and freezing parameterization Penner, parameterization 2012). (PH08) The isconcentration of that fitted deposi- to of that Young recommended (1974), by with Young (1974). the contact ice nuclei 2.1 Models The University of Michiganinteraction IMPACT of aerosol sulfate model with has non-sulfate aerosols a through detailed condensation, description coagulation, of as the 2 Methods The 3- transport model and generalan circulation o model (Wangfields and and Penner, 2010), meteorology as fieldsanthropogenic well forcing. for The as the o o examines the cloud water fieldsinvolving and feedbacks to mixed-phase cloud the fields forcing without from changes in aerosols. as the cloud waterFinally, field an and updated radiative totalscheme. forcing anthropogenic from forcing the is original presented and with the the new new scheme. 3- present the hydrophobic, hydrophilic and hygroscopic 5 5 25 15 20 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C for ◦ C. So ◦ BC/OM BC/OM noSCO BC/OM. BC/OM, 40 ff ff ff ff 57 BC/OM is − ff − BC/OM ff BC/OM particles ff BC/OM scheme, since we ff BC/OM is smaller for PD at NH ff BC/OM. In doing so, we preserve ff BC/OM burden. Hydrophilic and hy- BC/OM is confined mainly to regions ff ff 19994 19993 C and at water saturation is 0.03 %, 2 %, and 3 %, ◦ 40 − BC/OM is transported farther than hydrophobic ine simulations. In the 1BC simulation, the original PH08 ff BC/OM. Hydrophobic ffl ff ect of treating soot ice nucleation using the results of Koehler ff erences between the size distribution between the polydisperse ects on warm-phase and cirrus clouds are included in the in-line ff ff BC/OM is even more wide spread. The majority of the BC/OM is smaller for the PD in most places of the Northern Hemisphere ff ff BC/OM particles contribute 17.64 % and 12.43 %, respectively. The lifetime ff BC/OM particles increases with hygroscopicity from 0.45 to 0.95 to 4.55 days. ff ects as well as e Figure 2 shows the change in the hydrophobic, hydrophilic, and hygroscopic ff high latitudes (Fig. 2b).PD This in is the because industrial sulfate regions emissions in the increase NH significantly and in more the readily coat the surface of the are hygroscopic, contributing 69.93 % todrophobic the total of the number concentrations from PI toincrease PD due in to most anthropogenic emissions. placeshydrophobic Concentrations due to higher(NH) PD (Fig. emissions. 2a), However, and the the concentration concentration of of hydrophilic Figure 1 shows thedrophilic and PD hygroscopic horizontal distributionnear of emissions. Hydrophilic column integratedHygroscopic hydrophobic, hy- ice nucleation in mixed-phase clouds.scheme with The PD in-line and model PIe is emission run files described using in the Pennermodel. 3BC et al. (2009). Aerosol direct 3 Results 3.1 Aerosol fields for hydrophobic, hydrophilic, and hygroscopic Table 1 shows thescheme three is o used and thetreated sum as of one hydrophobic, species. hydrophilic,Day and For (PD) hygroscopic each and configuration, Pre-Industrial the (PI) model is aerosol run fields. twice PI with aerosol Present- fields are only applied to 2.3 Experiment set-up want to examine theet e al. (2009), whose measurementing includes but deposition/condensation/immersion no freez- contact freezing.(1974) Contact parameterization freezing fitted in our to modelmeasured the by is observation Blanchard represented (1957) of by (see the totalcontribution Yun Young number and from Penner, of 2012). contact contact This treatment ice freezing1 makes %). nuclei to the total ice nucleation very small (on the order of clude them as a heterogeneous IN.propane This burner is soot similar by to the Crawfordgeneously, observation et and of al. we internally (2011). scale mixed The theto second frozen the is fraction observation that of of theycontact PH08 multi-layer freeze freezing coated by hetero- treatment a lamp was factor black kept of soot the 15. by same DeMott This as is et in similar al. the (1999). 1- The fore, we increased the PH08and frozen reduced fraction it by by athe a temperature factor factor dependence of of specified 10 0.15 in forlowed for PH08. the hydrophilic hydrophobic Freezing “Koop” for line hygroscopic for particlesa homogeneous fol- short freezing distance of near water pure saturation.saturation dissolved However, the was solute frozen far at fraction smaller slightly than above water thatTherefore, predicted we by made a two homogeneoushigher assumptions freezing mechanism. . to The treat first the is freezing that of these particles hygroscopic particles freeze homogeneously, at so we ex- we assumed that di particles and our sooterties particles of would hygroscopic nothygroscopic particles. have soot a The measured at large frozen impactrespectively, fraction while on of that the hydrophobic, freezing predicted hydrophilic, prop- by and PH08 for the same conditions is 0.2 %. There- fractions of the polydisperse particles and 250 nm particles are similar at 5 5 25 20 15 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . ; i 2 N − ect . ff 2 in the − i BC/OM N, while N ff ective ra- ◦ ff erent from SCO case. ff 2.45 Wm − BC/OM parti- ff noSCO scheme. BC/OM. In general, ine mixed-phase an- ff , manuscript in prepa- ffl 2 − ) change from PI to PD i ects and is N ff , which is opposite to the sign N, caused by the decrease of (Fig. 3). Smaller ice e N in the 3BC 2 0.8 Wm i ◦ ◦ − − N BC/OM. When hygroscopic BC/OM scheme is very di BC/OM particles are included, there is ff ff ff ect of hygroscopic BC/OM forcing. The first is the decrease ff ff SCO case shows much larger increases that 19996 19995 erent freezing properties results in significant ff ine model. There is a larger increase in SCO case and smallest in the 3BC-noSCO case, ffl . i ine simulations because the aerosol and meteorology throughout the mid- north of 30 ect is included. That for the inline model, however, has N ffl ff 1 − BC/OM particles become hygroscopic more easily and are BC/OM scheme. However, the sign of the change depends ff ff ect (ADE) by clouds which produces a positive PD-PI SWCF, ff BC/OM with di ff causes a net conversion of liquid to ice in mixed-phase clouds, as ect is negative, and the Long-wave (LW) forcing is positive. The BC/OM does not, there is a smaller overall increase. ine mixed-phase cloud forcing. When hygroscopic i ff ff ffl N BC/OM (Fig. 2b). The 3BC ff ect is enhanced by a larger increase in emissions. The net whole-sky forcing ff noSCO case shows decreases north of 60 ective radius associated with the increase of ff ects including warm cloud, , and direct e ff increases from PI to PD predicted by the 3- The total anthropogenic forcing (including sulfate) using the 3BC scheme with the The treatment of Table 2 shows the anthropogenic forcing in mixed-phase clouds from the three cases. An increase in i all e tions in the PD, andin produces cirrus a cloud positive fraction is SWCFincrease not change very is from large. PI larger The to second forthan is PD, the if that in the emission the the anthropogenic decrease files emission emissiontener used files et here al., used (described 2006). in in Withof Storelvmo larger Penner the et aerosol et aerosol al. concentrations al., direct in (2012)and 2009) e PD, this (which there e are is a basedis larger on the blocking Den- same as thefields CF are in fixed and the no o direct e of the result of thisration). model The in reason Storelvmo et is al.freezing two (2012) are fold. ( included The in first cirruscluded is clouds that in here, both Storelvmo whereas homogenous only etsuppresses and homogeneous homogeneous al. heterogeneous freezing freezing, is (2012). results in- in Including decreased heterogeneous cirrus freezing ice number in concentra- cirrus clouds changes to the o cles are excluded ascompared to IN, the 1BC there case. isan When increase hygroscopic a by a 35 % factor ofThe decrease 6, two due in treatments to for the the hygroscopic large sootthropogenic net liquid particles forcing water anthropogenic that lead change varies to in forcing by a the almost net 3BC o a factor of 10,coupled from model 0.111 shows to a 1.059 Wm positive Net CF of 0.06 Wm in a smaller liquidreflectivity water and path increased in long-wave the transmissivity.itive The present-day, SW and result therefore forcing of a this anddominates reduced change the a is short-wave sign negative a of LW pos- the forcing. SW and As LW shown forcings. in Table 2, the second e second aspect is the decrease of liquid water mass mixing ratio (Fig. 4). This results at the Top-of-the-Atmosphere (TOA).forcing Therefore, from the anthropogenic this Short-wave e (SW) The decrease is largestconsistent in with the the 3BC changes in Two aspects contribute to the anthropogenic of ice e dius leads to more reflectedthe solar net radiation incoming and short-wave less radiation long-wave as transmission, reducing well as the net outgoing long-wave radiation in mixed-phase clouds usingNH the than o in theshows Southern increases Hemisphere of (SH) orderthe for 1 3BC l all three experiments. The 1BC case ratio decreases at most latitudes except north of 60 less likely to remain hydrophilic and even less likely3.2 to remain hydrophobic. Comparison of mixed-phase cloud waterFigure field 3 and radiative shows forcing the grid-mean ice number concentration ( hydrophilic strongly on the freezingacts ability as of a hygroscopic heterogeneouswhen IN hygroscopic in mixed-phase clouds, there isa a result larger of increase the in water Bergeron-Findeisen mass process. mixing Figure ratio 4 in shows the all change 3 in schemes the from liquid PI to PD. Liquid cloud mass mixing particles. Therefore, the also extend to the SH,N due to the enhanced e that predicted by the 1- 5 5 25 15 20 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , ine ect, ff ffl , 2009. , 2011. ects in mixed- ff ect of greenhouse ff a. R. Chen helped with , 2005. doi:10.1029/1999GL900580 estimated using the o doi:10.5194/acp-7-4203-2007 2 BC/OM at mixed-phase cloud − ff , 2005. ects in mixed-phase clouds, which ff erent aerosol indirect e doi:10.5194/acp-9-8917-2009 ff doi:10.5194/acp-11-9549-2011 , 2011. , H., Liu, D., McMeeking, G., Linke, C., Flynn, M., ects of aerosols on climate. Our results show ff , 2008. ff 19998 19997 doi:10.5194/acp-5-2935-2005 ect of ADE (0.67 Wm ff ect of hygroscopicity is considered, and how it is con- ff doi:10.1029/2004JD005674 doi:10.1029/2011JD015999 ). As a result, the SW forcing in mixed-phase clouds contributes J. E. P. and Y. Y. are grateful for support from US CRDF/NFS, NSF ATM 2 − ect comes from the decrease of optical depth due to the Bergeron- ff ect of anthropogenic aerosols on mixed-phase clouds is a warming. 2.12 % (Table 2). The magnitude of the mixed-phase cloud forcing is doi:10.1029/2007JD009266 ff ¨ ∼ ohler, O., Schnaiter, M., Saatho ¨ ohler, O., DeMott, P.J., Pechtl, S., and Yu, F.:Insights into the role of soot aerosols ect on warm clouds. This could counteract the warming e ff 68.7 % of the anthropogenic SW forcing in all clouds, and the LW forcing con- ∼ scription, evaluation, and interactions betweenRes.-Atmos., sulfate 110, and D18206, nonsulfate aerosols, J. Geophys. rico, C. M., Kireeva, E.and ice D., nucleation Khokhlova, activity T. of D.,Phys., hydrophobic and 11, and Shonija, hydrophilic 7906–7920, soot 2009. N. particles, K.: Phys. Chem. Cloud Chem. condensation nuclei in cirrus cloud formation, Atmos. Chem.2007. Phys., 7, 4203–4227, phase clouds, Atmos. Chem. Phys., 9, 8917–8934, Atmos. Chem. Phys., 5, 2935–2948, tensperger, U., and Weingartner,residuals E.: observed Black in carbon113, lower enrichment D15209, tropospheric in mixed atmospheric phase ice clouds, particle J. Geophys. 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We are grateful for computer time provided radiation model) from the inlinethe anthropogenic AIE SWCF to (1.61 Wm estimate the7.33 forcing from only tributes 0.32 very sensitive to whether the e Anthropogenic aerosol emissions are thought toindirect produce e negative forcing through their gases and thusthere has are large important uncertainties implications associatedhinders with for our their ability e predicting to fully climate determinethat the change. e the However, netThis e warming e Findeisen process. To estimateto the other importance clouds, of we mixed-phase removed the cloud e forcing relative act as IN in mixed phase clouds in the in-line simulation. 4 Discussion However, this number would be smaller if hygroscopic soot particles were allowed to 5 5 25 20 30 10 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ects, ff , 2010. doi:10.5194/acp- O, J. Phys. 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C., and Grant, K.: Climate forcing by carbonaceous and sulfate Mohler, O., Buttner, S., Linke, C., Schnaiter, M., Saatho 5 5 30 25 20 15 10 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). 2 − ects: warm, ff 2.45 − 0.04700.007 1.0592.22 0.111 1.059 0.06 0.111 0.0173 0.171 0.171 − − − − ects. ff 20002 20001 SWCF LWCF Net CF Net Whole-Sky BC/OM scheme BC/OM scheme and hygroscopic particlesBC/OM as scheme heterogeneous and ice no nuclei hygroscopic particles as heterogeneous ice nuclei ff ff ff SCOnoSCOnoSCO (inline) 2.28 1.106 0.118 3BC 3BC 1BC3BC 0.188 ine simulations. ffl Annual average anthropogenic cloud forcings (CF) and whole-sky forcings (W m O SCOnoSCO 3- 3- Schemes1BC Description 3BC 3BC 1- -line forcings are for mixed-phase clouds, while inline forcings include all e ff Table 2. O mixed-phase, and cirrus clouds and direct e Table 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

20 21 (c) , hy- (a) , and hygroscopic (b) , hydrophilic (a)

) 2 ). 2 − 20004 20003 BC/OM (mg m ff (c)

). ) 3 3 − PI annual hydrophobic of hygroscopic changes hydrophilic (c) and average (b), (a), - , and hygroscopic PD

(b) PD annual average horizontal PD distribution (a), average column integrated hydrophobic of annual PD annual average horizontal distribution of column integrated hydrophobic PD-PI annual average changes of hydrophobic BC/OM (µgm fBC/OM (ug/m Fig. 2. ff Fig. 1. drophilic

Figure 2. f

Figure 1. (b), hygroscopic (c) ffBC/OM (mg/m and hydrophilic 455 453 454 448 449 450 451 452 445 446 447 441 442 443 444 438 439 440 436 437 432 433 434 435 429 430 431 425 426 427 428 422 423 424 417 418 419 420 421 415 416 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

22 23 ).

1 − phase - ).

1 − simulations (mg kg (c) SCO simulations (# l (c) and 3BC (b) SCO mean liquid water mass mixing ratio (CLDLIQ) (CLDLIQ) mixing ratio mass water liquid mean mean ice number concentration in mixed - - 20006 20005 noSCO and 3BC (b) , 3BC (a) noSCO , 3BC (a) PI annualaverage changesof grid PI annualaverage changesof grid - - phase clouds from 1BC (a), 3BC_noSCO 3BC_SCO and from clouds (a), (b) (c) simulations 1BC phase (mg/kg) PD PD - PD-PI annual average changes of grid-mean ice number concentration in mixed-phase PD-PI annual average changes of grid-mean liquid water mass mixing ratio (CLDLIQ) in

Figure 4. mixed in Fig. 4. mixed-phase clouds from 1BC Fig. 3. clouds from 1BC

Figure 3. (a), 3BC_noSCO 1BC from clouds 3BC_SCO simulations and (#/L) (b) (c) 476 477 478 475 473 474 468 469 470 471 472 465 466 467 461 462 463 464 458 459 460 456 457