The Impact of Transport on the Physico-Chemical

Properties of Caribbean Aerosols during RICO: African

Dust and Pollution from North America

Olga L. Mayol-Bracero Institute for Tropical Ecosystem Studies

University of Puerto Rico, Río Piedras Campus

AFRICAN DUST WORKSHOP NASA & HU – UPR-M, Parguera, Lajas

21.June.2011

Introduction Objectives Experimental

• Sampling Locations• Measurements and Analyses

Results• Origin of the Air Masses• Aerosol Physical Properties • Chemical Composition and the Contribution of

Particulate Organic Matter Summary Acknowledgments

Outline

a better knowledge of the physical, chemical, and radiative properties of fine aerosols (especially of organics and mineral dust) and clouds.

a better understanding of the effects of aerosols on clouds and their interactions.

measurements in a globally representative range of natural/background and anthropogenically perturbed environments (background conditions, the Caribbean… PR!!!).

studies in the tropics• occupy ca. 50% of the surface of the globe• most photochemically active region of the atmosphere (highest

OH concentrations worldwide)• contribute significantly to the budget of gases and aerosols within

the Earth’s atmosphere• driving force for the Earth’s atmosphere circulation

To reduce the uncertainties in radiative forcing due to aerosols we need:

Rain In Cumulus over the Ocean experiment (RICO) - www.joss.ucar.edu/rico/

The RICO core objective was to characterize and understand the properties of trade wind cumulus clouds, with particular emphasis on determining the importance of precipitation.

Location: Caribbean - Antigua, Barbuda, and Puerto Rico 3 aircrafts (NCAR C-130, UK BAe-146, UW King Air), 1

research vessel (NSF Seward Johnson), and 4 ground-based stations (2 in Puerto Rico, 1 in Antigua, and 1 in Barbuda)

Sampling Period: November 2004 to January 2005 PRACS (2004) and PRADACS (2010 – 2012)

Two Fundamental RICO Questions: What is the spatial and temporal variability of

aerosol chemical and physical properties in the trade wind environment?

How do aerosols impact the microphysics of trade wind cumuli?

Aerosol Ground-Based Stations: Objectives

To determine the:

origin of the air masses sampled

physical and chemical properties of the atmospheric particles sampled:

• size, cloud condensation nuclei (CCN), mass concentration, and chemical composition

contribution of particulate organic matter (POM) to the total aerosol mass

BBaarrbbuuddaa

AAnnttiigguuaa

Caribbean Sea

Atlantic Ocean

Sampling Locations

Instrumentation: Dian Point (DP), Antigua (17.03 N, 61.48 W)

UPR-RP DLPI SFUs Weather Station

Meteo-France Condensation particle

counter (CPC) CCN counter SMPS

University of Leeds, UK Volatility system PCASP-X

Arizona State University Filter system (surface

analysis) University of Warsaw

and Scripps Institute Vaisala ceilometer Whole sky camera

Antigua

PCASP, CCN counter, SMPS, volatility system

DLPI

SFUs

Ceilometer

Sky Camer

a

DP, Antigua

Instrumentation: Cape San Juan (CSJ), Puerto Rico (18' 15 N, 66' 30 W)

UPR-RP DLPI MOUDI SFUs High-volume sampler Aethalometer Nephelometer Condensation particle

counter Weather Station

UNAM, Mexico OPC PMS LasAir

Max Planck Institute for Chemistry, Mainz, Germany

CCN counters (2) SMPS

University of Manchester, UK

Aerosol mass spectrometer

HTDMA Condensation particle

counter

University

East Peak1000 m

CSJ

S-Band weather radar

Puerto Rico

*CSJ is supported by NOAA/ESRL since 2004, it is part of the NASA AERONET, and it is one of the GAW regional stations.

CSJ, Puerto Rico

Instrumentation: East Peak, Puerto Rico (18o 16' N, 65o 45' W, 1051 m asl)

UPR-RP MOUDIs SFUs Cloud collector

UNAM, Mexico OPC PMS LasAir II Condensation particle

counter CCN counter FSSP-100, 2D-C, 2D-P Nephelometer Rain water collector Weather Station

Institute of Tropospheric Research, Leipzig, Germany

Condensation particle counter

PSAP

Max Planck Institute for Chemistry, Mainz, Germany

Aerosol mass spectrometer

East Peak, Puerto Rico

Cloud water collector

Darrel Baumgardner (UNAM) and Stephan Borrmann (MPIC)

Trailer

View looking upwind to CSJ, pointed to by the arrow.

2D-C and 2D-P

Online Measurements: Condensation particle counter Cloud condensation nuclei

counter PCASP, SMPS ASASP-X Volatility system

Analyses: Ion Chromatography (Na+, NH4

+, Ca2+, K+, Mg2+, Cl-, NO3

- SO42-,

acetate, formate, oxalate, and MSA)

Thermal/optical analysis (Total Carbon (TC), organic carbon (OC), and elemental carbon (EC).

Samplers: Aerosols – Stacked-filter units

and Dekati low-pressure impactor

Meteorological data

Daily Aerosol Optical Thickness Satellite Images from NOAA’s AVHRR / NESDIS

Air Mass Backward Trajectories NOAA ARL HYSPLIT model

(HYbrid Single-Particle Lagrangian Integrated Trajectory)

Measurements and Analyses

(1) Origin of the Air Masses

Clean Air Masses

African Dust

Anthropogenic Pollution from North America

http://www.arl.noaa.gov/ready.html

Air Masses Origin: Dian Point (DP) January 2006

http://www.arl.noaa.gov/ready.html

Air Masses Origin: Cape San Juan (CSJ)January 2006

(2) Aerosol Physical Properties

PCASP - Mean Particle Size Distribution - DPEnhancement due to anthropogenic pollution - Jan 20-21 (black line).

Enhancement in the accumulation and coarse modes, most likely due to dust particles - Jan 14-16 (blue line).

PCASP = Passive Cavity Aerosol Spectrometer Probe

SMPS + PCASP - Particle Size Distribution - Clean Air

Jan 19-20

SMPS = Scanning Mobility Particle Sizer

SMPS + PCASP - Particle Size Distribution - African Dust

Jan 14-16

Enhancement in the accumulation and coarse modes.

SMPS + PCASP - Particle Size Distribution Anthropogenic Pollution from North America

Jan 20-21

Significant enhancement in the accumulation mode (0.2-0.4 mm), some enhancement also in the coarse mode.

Aged pollution (North America and African Dust) changes size distributions in the accumulation and coarse modes, therefore, affecting also the CCN concentrations.

CCN Spectra

0

50

100

150

200

250

300

350

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Supersaturation, %

CC

N c

on

cen

tra

tion

, cm

-3

Clean

African Dust

Pollution North America (USA)

The increase in the coarse mode particles (African dust and NA pollution) seen before can also lead to higher concentrations of so-called giant CCN, and these can have an impact on precipitation formation, and thus affect the precipitation efficiency and cloud life-time.

DLPI Size-Resolved Mass Concentrations: Clean vs African Dust – Dian Point

0

5

10

15

20

25

30

0.01 0.1 1 10 100

Diameter, mm

dM

/dlo

gD

p, m g

m-3

Clean

African Dust

Filter Sampling – Mass Concentrations – Fine Fraction

Average total mass concentrations (Dp < 2 mm) are 1.4 mg m-3 for DP and 1.9 mg m-3 for CSJ, typical of remote marine areas. The highest concentrations were at CSJ and during the dust period. On average fine mass concentrations were ~1.6 mg m-3.

0

500

1000

1500

2000

2500

3000

3500

Clean African Dust Antropogenic Pollution

aver

age

mas

s co

ncen

trat

ion,

ng

m -3

Dian Point

CSJ

(3) Aerosol Chemical Composition and the

Contribution of Particulate Organic Matter)

TC Concentrations in Front and Back Quartz Filters (Positive Artifact)

0

50

100

150

200

250

300

350

400

Clean African Dust Antropogenic Pollution

TC

mas

s co

ncen

trat

ions

, ng

m -3

FQ-DP BQ-DPFQ-CSJ BQ-CSJ

The % of the positive artifact was on average 57%; therefore, not correcting for this will contribute to a significant overestimation of TC concentrations.

Positive artifact - adsorption of organic vapors on the quartz filters

TC and EC after Correction for the Positive Artifact

Uncorrected concentrations were on average 50 and 260 ng m-3 for the DP and CSJ, respectively. Corrected concentrations were 18 ng m-3 (DP) and 118 ng m-3 (CSJ). EC concentrations were at low-to-non detectable levels.

0

50

100

150

200

Clean African Dust Antropogenic Pollution

mas

s co

ncen

trat

ions

, n

g m

-3

TC-DP

EC-DP

TC-CSJ

EC-CSJ

ASASP-X: Particle Size Distribution-Volatility Spectra: African Dust

150˚C / SVOC 570˚C / OC

730˚C / NaCl270˚C / AMS

SVOC = semivolatile OC AMS = (NH4)2SO4

Small decrease in particle number due to the loss of SO4

2-. Little contribution by OC aerosol. Volatilization of NaCl. Significant amount of residual

refractory material (silicates, soot,..).

Average Particle Size Distribution-Volatility Spectra Anthropogenic Pollution from NA

150˚C / SVOC 570˚C / OC

730˚C / NaCl270˚C / AMS

• Significant loss of SO42- particles.

• Evidence of OC particles, due to a slight reduction in particle number from 270°C to 570°C.

• At 730°C, almost all particles >0.3 mm are volatilized.

SVOC = semivolatile OC AMS = (NH4)2SO4

Size-Resolved Mass Concentrations of Ca2+ and Mg2+: Clean vs African Dust

0

100

200

300

400

500

600

0.01 0.1 1 10 100

Diameter, mm

dM

/dlo

gD

p,

ng

m-3

Mg++ Clean Ca++ Clean Mg++ African Dust Ca++ African Dust

African Dust

Clean

Chemical Composition – Fine FractionClean Air, Dian Point

Cl/Na = 1.45 SO4/Na = 0.77 Ca/Na = 0.077 EC was not detected. nss-sulfate = 74 ng m-3

residual mass = 40%

Date: Jan 5-7, 2005

POM = particulate organic matter (OC’ * 1.8)

Marine Aerosol (Warneck, 1988)Cl/Na = 1.590SO4/Na = 0.885

Ca/Na = 0.058

nss-sulfate in remote/clean areas is about 200 ng m-3.

24.0%

2.9%

1.4%

3.0%

1.8%

0.4%

0.1%

0.0%34.7%

3.1%

0.3%

18.3%

8.8%

0.6%

0.5%0.0% Na+

NH4+ K+ Mg++ Ca++ AcetateFormateNO2- Cl- NO3- MalonateSO4= Oxalate MSAEC POM

Na+

Cl-

SO4=

POM

Chemical Composition – Fine Fraction African Dust, Dian Point

Cl/Na = 1.63 SO4/Na = 0.70 Ca/Na = 0.17 EC was detected. nss-sulfate = 128 ng m-3

higher Ca2+, lower POM residual mass = 62%

Date: Jan 11-14, 2005

24.8%

1.4%

1.7%

3.2%

4.1%

0.2%

0.1%

0.0%40.5%

3.6%

0.1%

17.5%

0.5% 0.3% 1.0%1.0% Na+

NH4+ K+ Mg++ Ca++ AcetateFormateNO2- Cl- NO3- MalonateSO4= Oxalate MSAEC POM

SO4=

Cl- Ca2+

Na+

Marine Aerosol (Warneck, 1988)Cl/Na = 1.590SO4/Na = 0.885

Ca/Na = 0.058

nss-sulfate in remote/clean areas is about 200 ng m-3.

Chemical Composition – Fine Fraction Anthropogenic Pollution from North America,

Dian Point

Cl/Na = 1.11 (sea-spray acidification)

SO4/Na = 2.03 Ca/Na = 0.08 nss-sulfate = 193 ng m-3

Date: Jan 21-24, 2005

18.4%

6.5%

1.1%

2.3%

1.5%

0.4%

0.1%

0.0%20.5%

4.5%

0.3%

37.5%

1.4%0.9%

0.0%4.6%

Na+ NH4+ K+ Mg++ Ca++ AcetateFormateNO2- Cl- NO3- MalonateSO4= Oxalate MSAEC POM

Na+

NH4+

Cl-

NO3-

SO4=

POM

Marine Aerosol (Warneck, 1988)Cl/Na = 1.590SO4/Na = 0.885

Ca/Na = 0.058

nss-sulfate in remote/clean areas is about 200 ng m-3.

Fraction of Particulate Organic Matter (POM)

NSSM = non-sea-salt aerosol mass = [mass – (Na+ + Cl-)]

Summary

Aged pollution from African Dust and from North America: increases the number of particles in the accumulation and coarse modes causes higher CCN concentrations the increase in the coarse mode could lead to higher concentrations of the so-

called giant CCN, having an impact on precipitation formation, and thus cloud life-time.

The positive artifact in carbonaceous samples is significant (~50%). The predominant aerosol species in all cases (Dp < 2 mm) were Cl-, Na+, and

SO4=. SO4

= was in higher concentrations during the polluted case. POM is representing a fraction of the total mass that can go from ~ 1 to ~ 40%

(average: 10 ± 16 %) (avg POM = ~115 ng m-3). POM/NSSM from 1 to 70%. Most significant amounts of organic matter are seen during pollution events;

nevertheless, based on the concentrations of species such as EC, OC, and nss- SO4

=, the anthropogenic activity during the sampling periods was very low. Pollution from North America: increase in SO4

=, NH4+, NO3

-, and POM; sea-spray acidification; highest concentrations of nss- SO4

=; and partially reacted sea-salt particles.

Based on the concentrations of species such as EC, OC, and nss- SO4=, in

general, the anthropogenic activity at both sampling sites was very low.

Acknowledgements F. Morales, G. Santos – UPR ITES RICO-PRACS participants (M. Repollet, A. Kasper-Giebl, H. Puxbaum, L.

Gomes, J.D. Allan, J.J.N. Lingard, J.B. McQuaid, D. Baumgardner, G. B. Raga, A. Kasper-Giebl, H. Puxbaum, L. Gomes, G.P. Frank, U. Dusek, M.O. Andreae, S. Borrmann, J. Schneider, S. Mertes, S. Walter, M. Gysel, M. Krämer, D. Baumgardner, G. B. Raga, F. García-García)

T. Novakov, T. W. Kirchstetter – Lawrence Berkeley National Lab. J. A. Ogren, P. Sheridan, E. Andrews – NOAA ESRL S. Decesari - Institute of Atmospheric Science and Climate-C.N.R.,

Bologna, Italy R. J. Morales-De Jesús - Physical Sciences Department, UPR-RP R. Rauber - University of Illinois Conservation Trust of Puerto Rico, Cabezas de San Juan El Yunque National Forest, PR Government of Antigua and Barbuda, special thanks to Ms. M. Mikael,

Steven, and Mr. Errol – FBO! NSF – Physical and Dynamic Meteorology and Atmospheric Chemistry

Thanks for listening!