VOCALS REx: Aerosol Physics at the Ocean Surface On the NOAA RV Ronald H. Brown October, November 2008

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1 VOCALS REx: Aerosol Physics at the Ocean Surface On the NOAA RV Ronald H. Brown October, November 8 Catherine Hoyle, NOAA PMEL Derek Coffman, NOAA PMEL Tim Bates, NOAA PMEL Trish Quinn, NOAA PMEL Lelia Hawkins, Scripps Institution of Oceanography David Covert, UW Dept. of Atmospheric Sciences Thanks to: Captain, Chief Scientist, Oceanographers, and the Crew of the Ron Brown

VOCALS REx GOAL Better understand aerosol, clouds and precipitation as interactive processes that in turn influence cloud properties - cloud cover, thickness and particle size and optics over the

2 VOCALS REx GOAL Better understand aerosol, clouds and precipitation as interactive processes that in turn influence cloud properties - cloud cover, thickness and particle size and optics over the South East Pacific. Hypotheses we are addressing two of many. 1a. Variability in the physico-chemical properties of aerosols has a measurable impact upon the formation of drizzle in stratocumulus clouds over the SEP. 1c. The small effective radii measured from space over the SEP are primarily controlled by anthropogenic, rather than natural, aerosol production; entrainment of polluted air from the lower free-troposphere is an important source of cloud condensation nuclei (CCN).

3 Panama Canal, entry from the Atlantic

5 Instrument Summary Optics: light scattering and absorption coefficients nephelometer and absorption photometers, 3 wavelength, humidified nephelometer Chemistry: 1 to 4 hour impactor, filter samples for major ions. Physics: number-size distribution nm to 1μm diameter DMPS, Differential Mobility Particle Sizer, to 8nm APS, Aerodynamic particle sizer, 8nm to 1μm Cloud Condensation Nuclei Concentration DMT, Thermal Gradient CCNC.1,.15,.,.3 and.6% SS. DMPS is a differential measurement 5 minute time resolution CCNC is a integral with 6 minute resolution. In order to relate the two: Integrate DMPS number-size distribution from 8nm to critical diameter, for a given CCNC supersaturation assuming a chemical composition - eg., ammonium sulfate.

6 Integral (over size) of particle number concentration from DMPS vs. droplet concentration from CCNC at.% and.6% supersaturation Number concentration, cm -3, DMPS integral assuming ammonium sulfate Chemical assumption: Ammonium sulfate CCN at indicated water vapor supersaturation.%.6%.% supersaturation R =.987 Intercept = -15± 4 Slope = 1.14 ±.15.6% supersaturation R =.98 Intercept = -11 ± 6 Slope = 1.15 ± Number concentration, cm -3, Droplet Measurement Technology CCN counter

7 Fri, Oct 31, 8: 5:5 to 11:45 UTC Lat. Lon , Generic marine number-size distribution Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=318, N.6%=55 Nuclei mode Aitken mode Accumulation mode Classical marine features Some influence from urban industrial sources in region 5 km, several days upwind Combustion Biomass burning Copper smelter SO Hoppel minimum Particle diameter, nm 1 Fri, Oct 31, 8: 5:5 to 11:45 UTC Cloud Condensation Nucleus concentration, CCNc, cm Lat. Lon , median CCN w/ quartile ranges Twomey, Squires power-law fit slope=.46, 1%SS CCNC= 65 CCN= C * (SS%) K, Twomey and Squires, Supersaturation, SS%

8 Wed, Nov 1, 8: 18:5 to 3:35 UTC Lat. Lon , Coastal, continental aerosol Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=577, N.6%=746 Dominant accumulation mode Minor Aitken mode (shoulder) Strongly influenced by urban industrial sources in region 5 km, several days upwind Combustion Biomass burning Copper smelter SO Particle diameter, nm Cloud Condensation Nucleus concentration, CCNc, cm Wed, Nov 1, 8: 18:5 to 3:35 UTC Lat. Lon , median CCN w/ quartile ranges Twomey, Squires power-law fit slope=.34, 1%SS CCNC= Supersaturation, SS%

9 Thu, Nov, 8: 1: to 1:45 UTC Lat. Lon. -19, Remote marine aerosol Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=438, N.6%=55 Dominant accumulation mode Minor Aitken mode (shoulder) Strongly influenced by urban industrial sources in region 5 to 1 km or more upwind Particle diameter, nm Cloud Condensation Nucleus concentration, CCNc, cm Thu, Nov, 8: 1: to 1:45 UTC Lat. Lon. -19, median CCN w/ quartile ranges Twomey, Squires power-law fit slope=.8, 1%SS CCNC= Supersaturation, SS%

10 RHB FlexPart model SO conc. at m

11 8/11/1 8/11/ SO, ppbv 8/11/14 8/11/16 8/11/18 VOCALS date 8/11/ 8/11/ 8/11/4 8/11/6 8/11/8 FLEXPART AGE-CLASS SO day 3day 4day 6day 8day 8/11/3

12 Pre POC 7 Oct 8 Sun, Oct 6, 8: 3:4 to 9:5 UTC Lat. Lon , Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=4, N.6%= Particle diameter, nm Number concentration, dn/dlogdp, cm POC 7 Oct 8 Mon, Oct 7, 8: 14: to 17:5 UTC Lat. Lon , Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=37, N.6%= Particle diameter, nm Post POC 7 Oct 8 Mon, Oct 7, 8: 18:55 to : UTC Lat. Lon , Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=41, N.6%=171 Accumulation mode is depleted in all cases. Within the more active POC region the Aitken mode is depleted as well Particle diameter, nm

13 Tue, Oct 8, 8: 3: to 17:5 UTC Lat. Lon , POC 8 Oct 8 Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=79, N.6%= Particle diameter, nm Post POC 8 Oct 8 Tue, Oct 8, 8: :45 to 6: UTC Lat. Lon , Number concentration, dn/dlogdp, cm Median dn/dlogdp Inter-quartile range Bars = instr. uncertainty Nacc=147, N.6%= Particle diameter, nm

14 Summary: Aerosol number-size distribution is consistent with past results in the SEP in terms of relation to POCs, i.e. depleted accumulation and Aitken mode concentrations. A spatial relation between number-size distribution features and POCs is evident, but a causal relationship is not yet clear. At times the effect of continental, pollution, aerosol extends far to the west of the continent into the SEP stratus field. Evidence for new particle formation in the MBL is minimal, it occurs in a very small volume fraction. The chemistry implies a relatively soluble aerosol. I.e. size, not chemistry, is the main controlling factor in terms of effective CCN.

16 footprint FlexPart model 8 day backtrajectory and SO probable source region contribution at m RHB

18 TERRA_817_151 AQUA_817_ Oct 9, Satellite and RHB camera images GOES1_817_198 RHB_817_18_4 true

19 GOES, 7 Oct 8, POC

Summary: Aerosol number-size distribution is generally consistent with past results in the SEP in terms of relation to POCs, i.e. depleted accumulation mode concentration.

20 Summary: Aerosol number-size distribution is generally consistent with past results in the SEP in terms of relation to POCs, i.e. depleted accumulation mode concentration. At times the effect of continental, pollution, aerosol extends far to the west into the stratus field. POC-like aerosol fields are extensive in time and space in the SEP MBL. Evidence for new particle formation in the MBL is minimal, it occurs in a very small volume fraction. The source of gas phase compounds for mass growth of Aitken mode to effective CCN size seems to be marine DMS and organic compounds, as well as SO and organic compounds advected from the continent. The chemistry implies a highly soluble aerosol. I.e. size, not chemistry, is the controlling factor in terms of effective CCN.

21 Summary: Aerosol number-size distribution is generally consistent with past results in the SEP in terms of relation to POCs, i.e. depleted accumulation and Aitken mode concentrations. A spatial relation between number-size distribution features and POCs is evident, but a causal relationship is not, yet. At times the effect of continental, pollution, aerosol extends far to the west into the SEP stratus field. Evidence for new particle formation in the MBL is minimal, it occurs in a very small volume fraction. The chemistry implies a relatively soluble aerosol. I.e. size, not chemistry, is the controlling factor in terms of effective CCN.

A review of VOCALS Hypothesis. VOCALS Science Meeting July 2009 Seattle Washington C. R. Mechoso, UCLA

A review of VOCALS Hypothesis. VOCALS Science Meeting July 2009 Seattle Washington C. R. Mechoso, UCLA A review of VOCALS Hypothesis VOCALS Science Meeting 12-14 July 2009 Seattle Washington C. R. Mechoso, UCLA VOCALS Strategy MODELING Operational Centers, Reseach Institutions, Universities REx AIRBORNE