Dominant Aerosol Chemical Components and Their Contribution to Extinction During the Aerosols99 Cruise Across the Atlantic



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Table 2. Concentrations, Standard Deviations ( 1), and Absolute Uncertainties (95% confidence level, values in parentheses) of the Mean of the Major Aerosol Supermicron (1.1 m < Daero < 10 m at 55% RH) Chemical Species for the Different Atlantic Ocean Air Mass Regimes.


Species

Air Mass Regime
























g m-3
North America

NH

Marine

Dust

Dust & Biomass Burning

Biomass Burning

SH Marine Tropics

SH Marine Temperate

























nssSO4=

0.09  0.13 (0.004)

< 0.001

0.03  0.10 (0.003)

0.03  0.09 (0.001)

0.03  0.03 (0.001)

0.07  0.09 (0.001)

0.03  0.04 (0.001)

























NH4+

< 0.001


< 0.001

< 0.001

< 0.001

< 0.001

< 0.001

< 0.001
























MSA
0.001  0.003 (0.0001)

0.005  0.004 (0.0001)

0.006  0.004 (0.0002)

0.009  0.008 (0.0002)

0.007  0.006 (0.0001)

0.03  0.018 (0.0005)

0.06  0.02 (0.001)

























Sea salt

9.2  4.6 (0.3)

8.0  2.8 (0.12)

19  2.9 (0.46)

8.2  4.9 (0.23)

4.6  2.6 (0.09)

6.4  3.2 (0.1)

9.5  2.8 (0.18)

























NO3-

2.30  1.6 (0.08)

0.23  0.23 (0.008)

0.76  0.25 (0.02)

1.3  0.55 (0.02)

0.94  0.55 (0.02)

0.19  0.11 (0.007)

0.14  0.06 (0.01)

























nss sol K+

< 0.001

0.008  0.03 (0.0004)

0.002  0.002 (0.0001)

0.01  0.01 (0.0003)

0.02  0.01 (0.0003)

0.004  0.003 (0.0001)

0.001  0.001 (0.0001)

























POM

0.67 

0.38  0.09 (0.07)

1.0 (0.16)

0.73 (0.14)

0.32  0.27 (0.2)

0.28  0.18 (0.07)

0.23  0.11 (0.11)

























BC

< 0.01

< 0.01

0.01 (0.01)

0.06 (0.02)

< 0.03

< 0.01

< 0.01

























Dust / trace elements

0.57 

0.26  0.34 (0.05)

21 (3)

24 (3.6)

1.9 (0.34)

0.17  0.21 (0.05)

0.06  0.03 (0.04)

























Al/Si

--

0.31  0.43 (0.03)

0.32 (0.02)

0.34 (0.02)

0.30 (0.02)

0.57  0.69 (0.39)

--

























Fe/Si

--

0.07  0.16 (0.005)

0.24 (0.01)

0.24 (0.01)

0.26 (0.02)

0.12  0.20 (0.01)

--

Table 3. Chemical Reactions Included in the Chemical Equilibrium Model AeRho.



Reaction

Crystallization RH

2H+(aq) + SO4= (aq)  H2SO4(aq)




H+(aq) + HSO4- (aq)  H2SO4(aq)




2NH4+(aq) + SO4= (aq)  (NH4)2SO4(aq)




NH4+ (aq) + HSO4- (aq)  NH4HSO4(aq)




2Na+ (aq) + SO4= (aq)  Na2SO4(aq)




Na+ (aq) + HSO4- (aq)  NaHSO4(aq)




2K+(aq) + SO4= (aq)  K2SO4(aq)




K+(aq) + HSO4- (aq)  KHSO4(aq)




H+(aq) + NO3- (aq)  HNO3(aq)




NH4+ (aq) + NO3- (aq)  NH4NO3(aq)




Na+ (aq) + NO3- (aq)  NaNO3(aq)




K+(aq) + NO3- (aq)  KNO3(aq)




H+(aq) + Cl-(aq)  HCl(aq)




NH4+ (aq) + Cl-(aq)  NH4Cl(aq)




Na+(aq) + Cl-(aq)  NaCl(aq)




K+(aq) + Cl+(aq)  KCl(aq)




2NH4+(aq) + SO4=(aq)  (NH4)2SO4(s)

401

NH4+(aq) + HSO4-(aq)  NH4HSO4(s)

221

2Na+(aq) + SO4=(aq)  Na2SO4(s)

591

Na+(aq) + HSO4-(aq)  NaHSO4(s)

0.052

2K+(aq) + SO4=(aq)  K2SO4(s)

625

K+(aq) + HSO4-(aq)  KHSO4(s)

625

NH4+(aq) + NO3-(aq)  NH4NO3(s)

322

Na+(aq) + NO3-(aq)  NaNO3(s)

302

K+(aq) + NO3-(aq)  KNO3(s)

625

NH4+(aq) + Cl-(aq)  NH4Cl(s)

473

Na+(aq) + Cl-(aq)  NaCl(s)

454

K+(aq) + Cl-(aq)  KCl(s)

624

1Tang and Munkelwitz [1994], 2Tang [1996], 3Cohen et al. [1987], 4Tang et al. [1997], 5No Data - assumed from KCl

Table 4. Regional Averages of Submicron (Daero < 1.1 m) and Supermicron (1.1 < Daero < 10 m) Densities and Real and Imaginary Portions of the Refractive Index Estimated from the Chemical Thermodynamic Equilibrium Model, AeRho. Values are Reported for 55% RH.



Region

Density, g cc-3

Refractive index

Refractive index










Real portion

Imaginary portion




Sub-m

Super-m

Sub-m

Super-m

Sub-m

Super-m

North America

1.47

1.26

1.51

1.42

2.3E-05

5.9E-05

NH Marine

1.37

1.30

1.45

1.44

6.3E-05

1.9E-05

African Dust

1.85

1.70

1.54

1.47

3.9E-03

4.0E-04

African Dust / Biomass Burning

2.11

1.94

1.66

1.49

7.0E-02

1.1E-03

Biomass Burning

1.91

1.56

1.69

1.46

5.8E-02

1.9E-04

SH Marine Tropics

1.67

1.32

1.57

1.44

5.4E-05

2.7E-05

SH Marine Temperate

1.76

1.30

1.58

1.44

1.8E-04

1.0E-05

Table 5. Accumulation and Coarse Mode Surface Area Fit Parameters (Mean Values and 1 Standard Deviation) at 55% RH.




Region

Accumulation mode

Coarse Mode Ia

Coarse Mode II


































S

Dgs

g

S

Dgs

g

S

Dgs

g




m cm-3

m




m cm-3

m




m cm-3

m

































North America
84  23

0.25  0.01

1.4  0.03

39  20

0.8  0.07

1.8  0.48

48  14

2.8 + 0.19

1.6 + 0.11

NH Marine

8  2

0.22  0.03

1.4  0.11

28  12

1.2  0.35

2.1  0.52

47  17

2.7 + 0.28

1.7 + 0.15

African Dust

11 2

0.18  0.01

1.4  0.03

50  16

0.9  0.16

1.9  0.22

82  17

2.1 + 0.11

1.6 + 0.06

African Dust / BB

52  9

0.27  0.01

1.7  0.08

78  17

1.7  0.04

1.7  0.02










Biomass Burning

52  13

0.27  0.01

1.5  0.03

17  6

1.8  0.09

1.7  0.06










SH Marine

Tropical

19  6

0.3  0.02

1.5  0.07

27  10

2.1  0.08

1.9  0.07










SH Marine

Temperate

24  4

0.25  0.01

1.3  0.03

53  7

2.4  0.11

2.1  0.13











a The coarse aerosol was fit with two lognormal modes in the North America, NH Marine, and Dust regions to accommodate a bimodal structure. The two-mode fit results in the best representation of both the total surface area concentration and the mean diameter of the coarse aerosol [Quinn and Coffman, 1998].

Table 6. Comparison of Mass Extinction Efficiencies (m2 g-1) Derived From Mie Calculations (Calculated) and From a Multiple Linear Regression (Empirical). Values are for the Size Range Dp,aer < 10 m (at 55% RH) and are Means Over the N America, NH Marine, Dust, Dust/Biomass Burning, and Biomass Burning Regions.
m2 g-1







Component

Empirical1

Calculated

Previously Reported

























Coefficient

Std Error

Mean

Range

Range



















Sea salt

2.2

0.3

1.5

1.1 – 2.4




NSS SO4= ion

5.7

2.1

3.4

2.3 – 5.6




Dust or trace

elements

0.9

0.1

1.2

0.7 – 1.9

1.073

0.73 – 0.794

POM

2.7

4.2

3.3

1.3 – 5.0

2.6 – 3.65

BC

3.62

45

3.1

1.9 – 4.4


























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