Sea Spray Aerosol and Climate Assessments: Model Results and Remotely Sensed Data

Transcription

1 Sea Spray Aerosol and Climate Assessments: Model Results and Remotely Sensed Data Nicholas Meskhidze North Carolina State University, Southern Ocean Workshop March 18-20, 2014

2 Why Do We Need to Study Sea Spray Aerosols? Background CDNC ~ 10 to 20 cm -3 Background CDNC ~30 to 40 cm -3 SWCF, W m 2 Minimum number of CDNC or aerosols, cm -3 [Hoose et al., GRL, 2009]

3 Interaction of the Major Types of Oceanic Emissions with the Lower Atmosphere [Carpenter et al., Chem Soc Rev, 2012]

4 Marine Organic Aerosol: Implications for Biological Source Long term measurements (Amsterdam Island) show that OC aerosol concentration seasonality similar to that of chlorophyll (Sciare et al., 2009 JGR) In the Southern Ocean, higher chlorophyll correlates with Lower liquid cloud effective radii Higher cloud droplet number concentration (Meskhidze and Nenes, 2006 Science)

5 Marine Organic Aerosol: Implications for Biological Source Mass fraction (%) Diameter (μm) [O Dowd et al., Nature, 2004] [Rinaldi et al., AMET, 2010]

6 Marine Organic Aerosol: Implications for Biological Source (submicron) Spracklen et al. (2008) Vignati et al. (2010) Fuentes et al. (2010) Long et al. (2011) Gantt et al. (2011) Gantt et al. (2012b) [Prather et al, PNAS, 2013]

7 From Sea Water To Aerosol In sea spray In seawater x 100 [Russell et al., PNAS, 2010]

8 mproving Organic Sea Spray Emissions et al., Reviews of Geophys, 2011]. t al., ACP, 2012b]

9 plementation Of Marine Organics In CAM5 del Configurations orizontal Resolution: 1.9 x 2.5 ; Vertical: 30 layers erosol: 5 sub- and 2 super-micron modes imulation: 5 years; Spin up period: 3 months årtensson et al. [2003] for 0.02 < Dp < 2.5 μm ong [2003] for 2.5 < Dp < 20 μm OA from isoprene, monotrpenes & MSA (CH 3 SO 3 H)

10 urface Concentration of Marine OA (ng m -3 )

11 an Derived Organic Aerosols: Climate Impact entage change in surface CCN (# cm 3 ) Percentage change in CDNC (# cm 3 ) Aerosol indirect forcing (W m 2 ) Without marine organics: 1.4 With marine organics: 1.3 Difference: 0.1 (7%)

12 al Average Marine POA Emissions (GEOS-Chem) submicron [Gantt et al., ACP, 2012b] Spracklen et al. (2008) Vignati et al. (2010) Fuentes et al. (2010) Long et al. (2011)

13 Model Evaluation of Concentrations Hourly Surface Concentration at Mace Head, Ireland

14 mary #1 ganics contribute 0.5 µg m -3 on average but > 3.5 µg m -3 ring episodic events to sea spray aerosol suming an external mixture of organics and sea-salt, cloud densation nuclei and cloud droplet number concentration rease by up to 20% hange in the model-predicted aerosol indirect forcing of.1 W m -2 (7%) is possible by including organic sea spray osol op-down marine POA emission scheme that best simulates monthly to hourly concentrations has an global submicron ission rate of ~ 6 Tg yr -1 isting marine POA emissions based on sea spray aerosol do produce the seasonality of observed concentration

15 ea Spray AOD: Remote Sensing vs Modeling GOCART - January GOCART - July [Smirnov etnetwork al., 2011] (MAN) Maritime Aerosol [Smirnov et al., 2011]

16 Why CALIPSO? [Photo courtesy of NASA] ood retrieval under low AOD conditions n inability of the legacy satellites to distinguish sea pray from other types of aerosols (i.e., desert dust, iomass burning, pollution).

17 Marine AOD as a Function Of Wind Speed [Kiliyanpilakkil & Meskhidze, 2011] SM - Smirnov et al. (2003) cm - Lehahn et al. (2010) GL - Glantz et al. (2009) ML - Mulcahy et al. (2008) H - Huang et al. (2010)

18 Remote Retrieval of CALIOP Lidar Ratio Fully elastic backscatter lidar with no molecular filtering capability Extinction-to-backscatter ratio (a.k.a. lidar ratio) for marine aerosols is prescribed to be 20 sr at 532 nm wavelength Measured lidar ratio of sea spray changes from 20 to 40 sr The Synergistic Optical Depth of Aerosols (SODA) is a product that uses CALIOP and Cloud Profiling Radar (CPR) measurements of the ocean surface reflectance to derive AOD Derived AOD is independent of CALIOP algorithm-derived extinction We can remotely diagnose lidar ratio using SODA AOD and CALIOP particulate integrated attenuated backscatter

19 Scatter Plot of SODA to CALIOP AOD for Different Wind Speed Regime S p =26 sr [Dawson et al., ACPD, 2014]

20 PDF of Sea Spray Aerosol Lidar Ratio [Dawson et al., ACPD, 2014]

21 NASA High Spectral Resolution Lidar (HSRL) Azores Field Campaign

22 Summary #2 Considerable differences remain in model-predicted and remotely sensed sea spray AOD values We developed a method to estimate CALIOP lidar ratio using remotely sensed data Paradoxically low retrieved (active remote sensing and sun-photometers) values of sea-salt AOD over the Southern Ocean Advances in remotely sensed techniques may enable us to determine relationship between sea spray optical properties and wind speed, season, relative humidity, sea surface temperature, and sea water dissolved organic carbon

23

24 Seasonal Lidar Ratio for 2 5 Grid Cells DJF JJA MAM SON [Dawson et al., ACPD, 2014]

25 Sea Spray Aerosol Workshop [Meskhidze et al., ASL, 2013]

26 Science Prioritization Matrix Parameter Current understanding Impact if achieved Difficulty/Resources Needed Source Function Bulk mass and number emissions Med Med Low Med Low Bulk chemical composition/hygroscopicity Med Low Med Low Med Low Size resolved mass and number emissions Med Low High Med Size resolved chemical composition/hygroscopicity Low High High Mixing state Low High High CCN number flux Med Low High Med Giant CCN Low Med High IN number emissions Low Med Med IN sources Low Med Med Whitecap fraction Med High Med Low Bubble spectra Med High Med Seawater/microlayer chemical composition Low High Med Size resolved organic speciation Low High High Optical Properties AOD Med High Med Low Refractive index Med Med Med Low Depolarization Med Med Low High Humidified scattering Med High Low Ångström exponent Med Med Low Med Absorption Ångström exponent Med Low Med Low Med Fluorescence Med Low Med Med Low Lidar ratio Med Low Med Med Marine Boundary Layer Budget Wet removal Low High Med Dry removal Med Low Med Med Photochemical aging Low High High Volatility Low Med Med Entrainment Med Low High Med Cloud processing Low High High

27 ntifying locations for studies where instrumentation, model results, and ote sensing products could be effectively brought together in a table and predictable environment. onclusions and Suggestions for Future Work ulation of a set of terminology that is consistent among anographers, atmospheric scientists, and computer modelers. ndardization of artificial sea water and laboratory intercalibration of spray production sources ndard oceanic, aerosol, and meteorological measurements that should included, if possible, in all field campaigns focusing on sea spray osol. odel intercomparison of the bulk and size-resolved number centration and chemical composition of marine aerosols, preferably in framework of AeroCom. ation of a size-resolved sea spray aerosol observational database that ludes chemical/biological composition, and number concentration.

28 Selection e vertical feature mask found 1 layer in the entire column e vertical feature mask ranked the layer as type: aerosol d subtype: clean marine e layer top was 2 km e relative error in due to random noise in molecular ckscatter was 50% e collocated SODA 5 km layer was composed of at least % shot-to-shot data (therefore increasing the signal to ise ratio) e total number of retrievals per 2º 5º grid cell ranked ove the first quartile of the grid cell frequency tribution ly nighttime data is used.

29 anic Sea Spray Climate Modeling Organic sea spray added to the model as additional mass (internally mixed) and as additional mass and number (externally mixed) Reduction in hygroscopicity parameter ( is compensated by increased number of aerosols Laboratory measurements vs. ambient data