Observation of air pollution aerosols and Asian dusts using the Asian Dust and aerosol lidar observation Network (AD-Net)

Similar documents
Continuous observation of aerosols in East Asia using a ground based lidar network (AD NET)

Development of EarthCARE ATLID data retrieval algorithm and validation plan using the ground-based lidar network

3D structure of Asian dust transport revealed by CALIPSO lidar and a 4DVAR dust model

OPTICAL MEASUREMENT OF ASIAN DUST OVER DAEJEON CITY IN 2016 BY DEPOLARIZATION LIDAR IN AD-NETWORK

Airborne High Spectral Resolution Lidar Aerosol Measurements and Comparisons with GEOS-5 Model

Data Assimilation of Satellite Lidar Aerosol Observations

Characterization of free-tropospheric aerosol layers from different source regions

Developments in CALIOP Aerosol Products. Dave Winker

Observation of Smoke and Dust Plume Transport and Impact on the Air Quality Remote Sensing in New York City

Observation of Aerosols and Clouds Using a Two-Wavelength Polarization Lidar during the Nauru99 Experiment

Vertical distribution of dust aerosols from 5 years of CALIPSO observations

Examining effect of Asian dusts on the AIRS-measured radiances from radiative transfer simulations

Structure of dust and air pollutant outflow over East Asia in the spring

Projects in the Remote Sensing of Aerosols with focus on Air Quality

Continuous Observations of Aerosol Profiles with a Two-Wavelength Mie-Scattering Lidar in Guangzhou in PRD2006

Satellite Constraints on Arctic-region Airborne Particles Ralph Kahn NASA Goddard Space Flight Center

Ground-based Validation of spaceborne lidar measurements

Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active/Passive Retrievals of Aerosol Extinction Profiles

EXTRACTION OF THE DISTRIBUTION OF YELLOW SAND DUST AND ITS OPTICAL PROPERTIES FROM ADEOS/POLDER DATA

Seasonal Aerosol Vertical Distribution and Optical Properties over North China Xing-xing GAO, Yan CHEN, Lei ZHANG * and Wu ZHANG

Physicochemical and Optical Properties of Aerosols in South Korea

Long-term aerosol and cloud database from correlative CALIPSO and EARLINET observations

SATELLITE AEROSOL COMPOSITION RETRIEVAL

Aerosol Retrieved from MODIS: Algorithm, Products, Validation and the Future

Global observations from CALIPSO

Sources and Properties of Atmospheric Aerosol in Texas: DISCOVER-AQ Measurements and Validation

Report on the Sand and Dust Storm Warning Advisory and Assessment System (SDS-WAS)

Aerosol-type-dependent lidar ratios observed with Raman lidar

A new perspective on aerosol direct radiative effects in South Atlantic and Southern Africa

EARTHCARE SCIENCE MISSION OBJECTIVES

Aerosol forecasting and assimilation at ECMWF: overview and data requirements

AEROSOL. model vs data. ECWMF vs AERONET. mid-visible optical depth of aerosol > 1 m diameter. S. Kinne. Max Planck Institute Hamburg, Germany

V. Danylevsky Astronomical observatory of National Taras Shevchenko university. Kyiv, Ukraine.

A study of the shortwave direct aerosol forcing using ESSP/CALIPSO observation and GCM simulation

Authors response to the reviewers comments

Direct radiative forcing due to aerosols in Asia during March 2002

CATS GSFC TEAM Matt McGill, John Yorks, Stan Scott, Stephen Palm, Dennis Hlavka, William Hart, Ed Nowottnick, Patrick Selmer, Andrew Kupchock

Annual mean AOT by MODIS/Terra in 2006

Assessment of sulfate aerosols and its uncertainty due to clouds using global models

ACTRIS aerosol vertical profiles: advanced data and their potential use in a aerosol observations/models combined approach

JMA Assimilation Update

Advanced characterization of aerosol properties through the combination of active/ passive ground-based remote sensing (and in situ measurements)

Steve Ackerman, R. Holz, R Frey, S. Platnick, A. Heidinger, and a bunch of others.

AEROSOL LIDAR ACTIVITIES AT ECMWF: STATUS AND PLANS

Satellite observation of atmospheric dust

A severe dust event over the Mongolian Gobi in 3-5 March, 2016

What are Aerosols? Suspension of very small solid particles or liquid droplets Radii typically in the range of 10nm to

How good are our models?

Physio-chemical and Optical Characterization of Anthropogenic and Natural Aerosol: Implications for Assessing Global Effects

CHARACTERIZATION OF PROPERTIES AND SPATIOTEMPORAL FIELDS OF MINERAL AEROSOL AND ITS RADIATIVE IMPACT USING CALIPSO DATA IN CONJUNCTION

The MODIS Cloud Data Record

in East Asia and West Pacific Ocean M.Yamada(NU), T.Nagatani(NU) D.Zhang(PUK), T.Shibata(NU)

Observation of Tropospheric Aerosol Using Mie Scattering LIDAR at Srisamrong, Sukhothai Province

Aerosol type how to use the information from satellites for models???

Satellite remote sensing of aerosols Past, present and future

Estimation of aerosol direct radiative forcing by Asian dust using sun/sky radiometer and

UKCA_RADAER Aerosol-radiation interactions

Atmospheric circulation analysis for seasonal forecasting

Improvement of the retrieval of aerosol optical properties over oceans using SEVIRI

CALIPSO Data Products: progress and status

Simultaneous Dust and Pollutant Transport over East Asia: The Tripartite Environment Ministers Meeting March 2014 Case Study

Aerosol optical properties over east Asia determined from ground-based sky radiation measurements

Monitoring Sand and Dust Storms from Space

The EarthCARE mission: An active view on aerosols, clouds and radiation

Characterization of Atmospheric Mineral Dust from Radiometric and Polarimetric Remote Sensing

Can a change of single scattering albedo in Amami-Oshima in a low pressure condition be explained by GCM simulations?

CALIPSO measurements of clouds, aerosols, ocean surface mean square slopes, and phytoplankton backscatter

Current and Future Impacts of Wildfires on PM 2.5, Health, and Policy in the Rocky Mountains

Comparison of NASA AIRS and MODIS Land Surface Temperature and Infrared Emissivity Measurements from the EOS AQUA platform

GLAS Atmospheric Products User Guide November, 2008

SYNERGETIC USE OF ACTIVE AND PASSIVE REMOTE SENSING INSTRUMENTS FOR THE SEASONAL VARIANCE OF AEROSOLS OVER CYPRUS

Validation experiments of GPM/DPR on the pure oceanic precipitating clouds by instruments on board R/V Mirai

Verification of Aerosols Loading Over Kano: A Theoretical Estimation via Mathematical Rudiments

Aerosol Optical Depth Variation over European Region during the Last Fourteen Years

Improving the CALIPSO VFM product with Aqua MODIS measurements

Spaceborne Aerosol and Ozone Lidars for Air Quality Applications

Interannual variation of MODIS NDVI in Lake Taihu and its relation to climate in submerged macrophyte region

PHEOS - Weather, Climate, Air Quality

Assessment of Ozone Variability in East Asia during Recent Years

Satellite analysis of aerosol indirect effect on stratocumulus clouds over South-East Atlantic

THE GLI 380-NM CHANNEL APPLICATION FOR SATELLITE REMOTE SENSING OF TROPOSPHERIC AEROSOL

REMOTE SENSING OF THE ATMOSPHERE AND OCEANS

MAX-DOAS air quality observations at Phimai,

Spatial Variability of Aerosol - Cloud Interactions over Indo - Gangetic Basin (IGB)

Description of Precipitation Retrieval Algorithm For ADEOS II AMSR

Radiation in the atmosphere

Life Cycle of Convective Systems over Western Colombia

Dust and its Role in Tropospheric Chemistry A Modelers View

Simulation of UV-VIS observations

Satellite-derived environmental drivers for top predator hotspots

Preliminary testing of new approaches to retrieve aerosol properties from joint photometer-lidar inversion

Low Arabian dust extinction-to-backscatter ratio

Systematic coordinated Saharan dust profiling over Europe in the frame of the EARLINET project ( )

Aerosol Air Mass Distinctions over Jalisco using Multi-Angle Imaging Spectroradiometer

Regional Air Quality Monitoring and Forecasting using Remote Sensing Satellites, Ground-level Measurements and Numerical Modelling

GAMINGRE 8/1/ of 7

Aerosols and Clouds: Long-term Database from Spaceborne Lidar Measurements

An Observational Study of the Relationship between Cloud, Aerosol and Meteorology in Marine Stratus Regions

VERTICAL STRUCTURE OF THE DUST LAYER AND HIGH- AND MIDDLE- LEVEL CLOUDS OVER THE TAKLAMAKAN DESERT, CHINA BY LIDAR

Atmospheric Lidar The Atmospheric Lidar (ATLID) is a high-spectral resolution lidar and will be the first of its type to be flown in space.

Transcription:

Shipborn lidar observation. Two lidar systems were installed on RV Mirai (JAMSTEC) Observation of air pollution aerosols and Asian dusts using the Asian Dust and aerosol lidar observation Network (AD-Net) Nishizawa, T., N. Sugimoto, I. Matsui, A. Shimizu, A. Higurashi NIES lidar group

Asian Dust and aerosol lidar observation Network (AD-Net) Optical/microphysical properties of total aerosols and each aerosol component are essential to understand atmospheric environment and climate change. Observation Compact 2 (532, 1064nm) + 1 Mie lidar with automatically measurement capability 20 sites ground based network observation in East Asia (2001~) + Ship-borne measurements (1999~, vessel MIRAI (JAMSTEC)) [Sugimoto et al., 2001; 2005] Data analysis Classify aerosol components and Retrieve their extinctions at each layer (assuming external mixture of several aerosol component) 1 (532)+1 data Dust (nonspherical) + Air-pollution (Spherical) (1 +1 method) [Sugimoto et al., 2003; Shimizu et al., 2004] => Ground-based lidar data & Satellite-borne lidar (CALIOP) 2 +1 data Dust (nonspherical) + (2 +1 method) Air-pollution (Spherical / Small) + Sea-salt (Spherical / Large) [Nishizawa et al., 2007,2008,2011]

Asian Dust and aerosol lidar observation Network (AD-Net) Mineral dust Ulaanbaatar Lanzhou Biomass burning Forest fire Sainshand Hefei Shenzhen Zamynuud Beijing* Niigata Seoul Toyama Sendai Daejeon * Matsue Tsukuba* Chiba Fukuoka** * Tokyo Jeju Osaka Fukue Nagasaki * Industrial Hedo* Sapporo 20 sites Phimai* (532,1064)+ (532) * (532,1064)+ (532)+ (532 Raman) ** (355)+ (355)+ (355 Raman)

Lidar & Data analysis NIES lidar network (2) Realtime data processing system ΔZ=30m ΔT=15min Dust event Two-wavelength (1064nm, 532nm) Mie-scattering lidar with polarization channels at 532nm. (Raman receivers (607nm) are being added at several observation sites.) Extinction coefficient estimates of dust (left) and spherical aerosols (right) for primary locations (April 2009). http://www-lidar.nies.go.jp/ad-net/index.html

Dust March 21-31, 2004 Beijing Dust Spherical aerosols Air pollution Method for estimating the extinction coefficients of dust and spherical aerosols using the depolarization ratio

dust events Sainshand Sapporo Niigata Seoul* Toyama Sendai Matsue* Tokyo Fukue Hedo* (532,1064)+ (532) * (532,1064)+ (532)+ (532 Raman) ** (355)+ (355)+ (355 Raman)

Feb 2011 dust non-dust Beijing* Sapporo Niigata Seoul* Toyama Sendai Matsue* Tokyo Fukue Hedo* (532,1064)+ (532) * (532,1064)+ (532)+ (532 Raman) ** (355)+ (355)+ (355 Raman)

Lidar dust extinction coefficient has high correlation with dust PM2.5 (Kaneyasu et al., J. Jpn. Soc. Atmos. Environ. 2012)

Asian dust study using 4D-Var data assimilation NIES lidar network (3) 4DVAR data assimilation of Asian dust using the NIES lidar network data (Yumimoto et al. 2007, 2008) Comparison of the assimilated dust transport model with CALIPSO data (Hara et al. 2009) Please see the publication list at http://www-lidar.nies.go.jp/~cml/english/publicationse.html

Application of the lidar data to epidemiological studies Near-surface (120m-1km) dust and non-dust aerosol extinction coefficient used in the epidemiological study.

Publications on the epidemiological studies using the lidar data -Kanatani, K. T., I. Ito, W. K. Al-Delaimy, Y. Adachi, W. C. Mathews, J. W. Ramsdell, and Toyama Asian Desert Dust and Asthma Study Team, 2010: Desert-dust Exposure is Associated with Increased Risk of Asthma Hospitalization in Children, Am. J. Respir. Crit. Care Med. 182(12) 1475-81, doi:10.1164/rccm.201002-0296oc. -Onishi, K., Y. Kurosaki, S. Otani, A. Yoshida, N. Sugimoto, Y. Kurozawa, Atmospheric transport route determines components of Asian dust and health effects in Japan, Atmospheric Environment 49 (2012) 94-102, doi:10.1016/j.atmosenv.2011.12.018. (Subjective symptoms) -Kashima, S., T. Yorifuji, T. Tsuda, A. Eboshida, Asian dust and daily all-cause or cause-specific mortality in western Japan, Occup Environ Med 2012;00:1 8. doi:10.1136/oemed-2012-100797. -Ueda, K., A. Shimizu, H. Nitta, K. Inoue, Long-range transported Asian Dust and emergency ambulance dispatches, Inhal Toxicol. 2012 Oct;24(12):858-67. doi: 10.3109/08958378.2012.724729.

Asian Dust and aerosol lidar observation Network (AD-Net) Optical/microphysical properties of total aerosols and each aerosol component are essential to understand atmospheric environment and climate change. Observation Compact 2 (532, 1064nm) + 1 Mie lidar with automatically measurement capability 20 sites ground based network observation in East Asia (2001~) + Ship-borne measurements (1999~, vessel MIRAI (JAMSTEC)) [Sugimoto et al., 2001; 2005] Data analysis Classify aerosol components and Retrieve their extinctions at each layer (assuming external mixture of several aerosol component) 1 (532)+1 data Dust (nonspherical) + Air-pollution (Spherical) (1 +1 method) => Ground-based lidar data [Sugimoto et al., 2003; Shimizu et al., 2004] 2 +1 data Air-pollution (Spherical / Small) + (2 +1 method) Sea-salt (Spherical / Large) + Dust (nonspherical) [Nishizawa et al., 2007,2008,2011] => Ship-born lidar data & Satellite-borne lidar (CALIOP/NASA)

Aerosol component retrieval for Shipborn lidar & satelliteborn lidar (CALIOP/NASA) [Nishizawa et al. 2011] Optical model (RH=70%) Pacific ocean, 8/2, 2006 DS Clean maritime environment 532, AP SS DS [Kurogi & Okamoto 2012] 532, 1064 r m 0.13 3.0 2.0 S 55 20 48 WS 0 0 0.3 SS r m : mode radius, S: lidar ratio : depolarization ratio AP Air-pollution: small-size / spherical (moderate-absorption) Dust : large-size / non-spherical (moderate absorption) Sea-salt : large-size / spherical (weak-absorption) Assumption: External mixture of 3 components at each layer Optical properties are prescribed DS (AP, SS): spheroid (spherical) <= Dubovik et al., [2006] WS, SS : hygroscopic growth => Change optical model depending on RH data (ECMWF) SS DS Total

Spring (2006) Optical thickness for each component [Kurogi & Okamoto 2012] AP SS DS ummer (2006) Fall (2006) Winter (2006~ 2007) *Averaged every 3 3 grid for day and night

AOT comparison with MODIS [Kurogi & Okamoto 2012] Mar.-May, 2006 Jun-Aug., 2006 Lidar MODIS Sep.-Nov. 2006 Dec.-Feb., 2006-2007 Lidar MODIS Biomass-burning aerosols (BC, OC) Ocean: AOT (MODIS) > AOT (Lidar) Land: AOT (MODIS) < AOT (Lidar) *Averaged every 3 3 grid for daytime

Introduction of more advanced lidar to AD-Net Independent extinction (α) measurement is useful to classify weak/strong light absorption particles [Nishizawa et al., 2008] (Lidar ratio = extinction/backscatter: e.g., BC~100sr, Dust~50st, Sea-salt~20 at 532nm) Data analysis Combined use of HSRL(532) and 2 (532,1064) Mie lidar 1 +2 data Sulfate-Nitrate-OC (Small / Weak absorption) + (1 +2 method) BC (Small / Strong absorption) + Dust (Large) [Nishizawa et al. 2008] Ground-based network measurement 2 +1 Mie lidar + 1α N 2 Raman (607) channel with automatically measurement capability [1α+2 +1 lidar] (8 sites in the NIES Lidar Network) [Xie et al., 2008] Dual wavelength (355, 532nm) HSRL + 1 (1064)+2 (1064,532) Mie lidar with automatically measurement capability [2α+3 +2 lidar] [Nishizawa et al., 2008,2010] Ship-borne measurement (MIRAI) One wavelength HSRL + 1 (1064)+1 (532) Mie lidar with automatically measurement capability [1α+2 +1 lidar]

Asian Dust and aerosol lidar observation Network (AD-Net) Mineral dust Ulaanbaatar Lanzhou Biomass burning Forest fire Sainshand Hefei Shenzhen Zamynuud Beijing* Niigata Seoul Toyama Sendai Daejeon * Matsue Tsukuba* Chiba Fukuoka** * Tokyo Jeju Osaka Fukue Nagasaki * Industrial Hedo* Sapporo 8 sites Phimai* (532,1064)+ (532) * (532,1064)+ (532)+ (532 Raman) ** (355)+ (355)+ (355 Raman)

System outline Mie-Raman lidar System picture PMT (607 Raman) APD (1064nm) PMTs Measured parameters Copol backscatter Crosspol backscatter Total backscatter (1064nm) Raman backscatter (607nm) Optical properties 532nm Particle Extinction ( 532 ) 532nm Particle Backscatter ( 532 ) 532nm Particle depolarization ( 532 ) 1064nm Attenuated backscatter ( 1064 )

Data analysis Raman backscatter (607nm) Co-backscatter Crossbackscatter Total backscatter (1064nm) Noise reduction (Wavelet Transform) Averaging ( Z=120m, t=1h) Geometric correction Particle Extinction 532 Particle Backscatter 532 Particle Depolarization 532 Attenuated backscatter 1064 Feature mask Molecule / Aerosol / Cloud PBL height Retrieve aerosol component extinction (BC, Dust, Sea-salt, Sulfate-Nitrate-OC ) Note: Daytime Raman channel data are not used due to contamination of sunlight.

Example of analysis [Seoul, 12-15 May 2010] Raman signal (607nm) Attenuated Backscatter Total dep. Feature mask Particle Extinction Particle Backscatter Lidar ratio Feature mask Blue:Spherical aerosols Brown: non-spherical aerosols Red:Clouds Yellowish green:molecules Green:PBL height *Use 1064 attenuated backscatter and 532nm total depolarization data [Shimizu et al., 2004; Hagihara et al., 2010] ~0.3km -1 ~0.005sr -1 km -1 40~80 sr ΔZ = 120 m ΔT = 60 min

Example of analysis [Cape Hedo (Japan), 19-22 Mar. 2010] Raman signal (607nm) Attenuated Backscatter Total dep. Feature mask Feature mask Blue:Spherical aerosols Brown: non-spherical aerosols Red:Clouds Yellowish green:molecules Green:PBL height *Use 1064 attenuated backscatter and 532nm total depolarization data [Shimizu et al., 2004; Hagihara et al., 2010] Particle Extinction Particle Backscatter Lidar ratio 20~80 sr ΔZ = 120 m ΔT = 60 min

Light absorption Scatter plot, Cape Hedo Aerosol optical properties averaged in PBL Plot data in autumn (Sep. ~ Nov.) in 2010 and 2011 High Nonspherical Spherical Low Small Particle size Large OPAC model: Spheroid dust model: BC SF-NT-OC Sea-salt Spheroid dust

1 +2 +1 algorithm Retrieve extinction coefficients for 4 aerosol components SF-NT-OC: small-size / spherical / moderate-absorption Dust : large-size / non-spherical / moderate absorption Sea-salt : large-size / spherical / weak-absorption Black carbon: small-size / spherical / strong-absorption Assumption: External mixture of 4 components at each layer Optical properties are prescribed DS (AP, SS, BC): spheroid (spherical) <= Dubovik et al., [2006] Mode radius [um] Standard dev. Refractive index Lidar ratio (532nm, sr) Dep. Backscatter color ratio (1064/532) SF-NT- OC 0.13 1.6 1.41 2 10-3 Dust BC Seasalt 2.0 2.2 1.51 3 10-3 0.05 2.0 1.75 0.4 3.0 2.1 1.36 3 10-9 55 48 101 20 0.02 0.30 0.02 0.02 0.34 0.98 0.23 0.67

Attenuated backscatter SF-NT-OC Total Dep. Sea-salt Attenuated backscatter (1064nm) Dust Feature mask BC Particle extinction Mar 2010 17 19 21 23 25 27 29 ΔZ = 120 m ΔT = 60 min Particle backscatter Lidar ratio BC extinction is too high? SF-NT-OC is too low? => Validation is needed. => Aerosol optical models should be improved Particle Dep. Mar 2010 17 19 21 23 25 27 29 Cape Hedo, Okinawa, Japan (3/17-28,2010)

Mie-Raman lidar observation at Phimai, Thailand (2012 ~ ) 2012 Mie attenuated backscatter coefficient (532) [/km/sr] 30 Mar. ~ 2 Apr. 2012 Total depolarization ratio (532) [%] Mie attenuated backscatter coefficient (1064) [/km/sr] VFM Particle extinction coefficient [/km] Particle backscatter coefficient [/km/sr] Lidar ratio [sr] 50~70sr J F M A M J J A S O N D Lidar ratio for biomass burning aerosols AERONET : Cattrall. 2005: 60±8 (Africa / S. America) Omar. 2009 : 70 (all AERONET data) Lidar (EARLINET) Muller. 2007 : 53±11 (Siberia/Canada)

Summary We have conducted ground-based lidar network observation and continue it. The provided data are useful for studying Asian dust and air pollution aerosols. We improved the NIES ground-based network lidars by adding a N 2 Raman scatter measurement channel (607nm). This system provides 1 (532)+2 (532,1064)+1 (532) data at nighttime. We developed an algorithm to estimate vertical profiles of 532nm extinction coefficients of black carbon, dust, sea-salt, and SF-NT-OC aerosols using the 1 +2 +1 data. The particle optical properties, PBL height, and scene classification identifiers are automatically estimated from the lidar data and their quick-looks and archives are provided on the website (http://www-lidar.nies.go.jp/shingakujutsu/raman/). Error analysis and validation of the developed aerosol classification algorithm are needed in the future. Derived particle optical properties such as lidar ratio are useful for characterizing aerosol types such as biomass burning.

Application of the developed aerosol component classification algorithms to EarthCARE lidar ATLID. EarthCARE is a joint Japanese (JAXA)-European (ESA) satellite observation mission for understanding the interaction between clouds, radiative and aerosol processes in the earth climate. ATLID is a HSRL providing 1α+1β+1δ at 355nm. For more advanced aerosol component classification and aerosol typing, Observation by multi-wavelength Raman lidar and HSRL with more channels => Lidar development Simultaneous measurements by active sensor (lidar) and passive sensor (e.g., Skyradiometer) and their combined analysis. => Continue and develop the cooperative observation between SKYNET and AD-Net

NIES lidar Network Data * Only night time Lidar Data Site Status Ground-based measurements Mie lidar 2 (532,1064) + 1 (532) Mie-Raman lidar 1 (532)*+2 (532,1064) +1 (532) Mie-Raman lidar Two-wavelength HSRL Shipborne measurements 1 (355)*+1 (355) +1 (355) 2 (532,355) 3 (1064,532,355) 2 (1064,532) Mie lidar 2 (532,1064) + One-wavelength HSRL 1 (532) 1 (532)+2 (532,1064) +1 (532) 14 sites in East Asia 7 sites (Japan, China, Korea, Thai) 1 site (Fukuoka) 1 site (Tsukuba) 2001~ 2008~ 2012~ Under development R/V Mirai 1999~ R/V Mirai 2011

Heavy dust case Error in the extinction coefficient caused by incorrect S 1 and D Light dust case (Shimizu et al. SOLA 7A, 1-4, 2011.)

May 2012 Non-dust Dust smok e 201205

Latitude Study of regional air pollution (Climatology of non-dust aerosols) Longitude

Seasonal variation of vertical profiles of non-dust aerosol Jul 2006- Dec 2008 (Hara et al., SOLA 2011)

Matsue, Japan, 2010 BC extinction is too high? SF-NT-OC is too low? => Validation is needed. =>Aerosol optical models should be improved SF-NT-OC Sea-salt Dust BC 1 2 3 4 5 6 7 8 9 10 11 12 Month 1 2 3 4 5 6 7 8 9 10 11 12 Month