AerosolsAerosols

Catherine F. CahillCatherine F. CahillGeophysical Institute and Department Geophysical Institute and Department

of Chemistryof ChemistryUniversity of Alaska FairbanksUniversity of Alaska Fairbanks

Aerosols during RUSALCAAerosols during RUSALCA

•• Sampling methodSampling method•• Analysis methodsAnalysis methods•• Results and interpretationResults and interpretation•• Comparison with other studiesComparison with other studies•• ConclusionsConclusions•• Future workFuture work

Sampling MethodSampling Method

•• The aerosol sampler was a 3The aerosol sampler was a 3--stage DRUM stage DRUM aerosol aerosol impactorimpactor with a 2.5 with a 2.5 μμm cutm cut--point point cyclone inletcyclone inlet

•• The three size cuts of the sampler are:The three size cuts of the sampler are:–– 2.5 to 1.15 2.5 to 1.15 μμmm–– 1.15 to 0.34 1.15 to 0.34 μμmm–– 0.34 to 0.1 0.34 to 0.1 μμmm

•• Continuous sampling with 3.6 hour Continuous sampling with 3.6 hour resolution from August 6 to 24, 2004resolution from August 6 to 24, 2004

Aerosol SamplerAerosol Sampler

30 cm

3-stage DRUM aerosol impactor

The DRUM on the Professor Khromov.

Analysis MethodsAnalysis Methods

•• Elemental concentrations by Synchrotron Elemental concentrations by Synchrotron XX--ray Fluorescenceray Fluorescence–– Lawrence Berkeley National Laboratory Lawrence Berkeley National Laboratory

Advanced Light SourceAdvanced Light Source–– 42 elements between sodium and lead42 elements between sodium and lead

•• Mass concentration by Mass concentration by ββ--gaugegauge

Representative ElementsRepresentative ElementsRUSALCA Sodium, Potassium, Zinc, Calcium and Sulfur

(0.34 to 1.15 μm)

0

50

100

150

200

6 8 10 12 14 16 18 20 22 24

Day in August (GMT), 2004

Na,

K, Z

n an

d C

a C

once

ntra

tion

(ng/

m3)

0

800

1600

2400

3200

S Concentration (ng/m

3)

Na K Zn Ca S

Representative Elements (cont.)Representative Elements (cont.)

•• Very cleanVery clean•• The periods in Nome are the dirtiestThe periods in Nome are the dirtiest•• Influence of different sources is very Influence of different sources is very

episodicepisodic•• Sulfur has the highest concentrationsSulfur has the highest concentrations

Sea SaltSea SaltRUSALCA Sodium, Magnesium, Chlorine (0.34 to 1.15 mm)

0

50

100

150

200

6 8 10 12 14 16 18 20 22 24

Day in August (GMT), 2004

Na

and

Mg

Con

cent

ratio

n(n

g/m

3)

0

200

400

600

800

Cl C

oncentration (ng/m3)

Na Mg Cl

Sea Salt Sea Salt RUSALCA Cl/Na, S/Na and Zn/Ni (0.34 to 1.15 μm)

0

20

40

60

80

100

120

140

160

6 8 10 12 14 16 18 20 22 24

Day in August, 2004

S/N

a an

d Zn

/Ni

0

5

10

15

20

25

30

35

40

Cl/N

a

Zn/Ni S/Na Cl/Na

Sea SaltSea Salt

Aug.

20

Aug.

8

Aug.

14

Meteorological backwards- trajectories are oceanic when sea salt is the dominant aerosol type.

SoilSoilRUSALCA Aluminum,Calcium, Iron and Silicon (0.34 to 1.15 μm)

0

10

20

30

40

50

60

70

80

6 8 10 12 14 16 18 20 22 24

Day in August, 2004

Al,

Ca,

and

Fe

Con

cent

ratio

n(n

g/m

3)

0

10

20

30

40

50

60

70

80

Si Concentration (ng/m

3)

Al Ca Fe Si

VolcanoVolcano

Aug.

13

Aug.

1

Aug.

7

The soil elements observed on August 13th appear to be associated with volcanic activity at Sheveluch on the northern Kamchatka peninsula.

We did not see any Gobi or Taklimakan dust during this cruise.

SmokeSmokeRUSALCA Silicon and Potassium (0.34 to 1.15 μm)

0

50

100

150

200

250

300

350

400

450

6 8 10 12 14 16 18 20 22 24

Day in August, 2004

Si C

once

ntra

tion

(ng/

m3)

0

40

80

120

K C

oncentration (ng/m3)

Si K

SmokeSmokeThe high potassium concentrations in and near Nome at the end of the cruise were due to the high concentrations of wildfire smoke from fires in Interior Alaska reaching the ship.

Aug.

24

Aug.

12

Aug.

18

Wildfire SmokeWildfire Smoke•• Wildfires in subWildfires in sub--Arctic and Arctic and

Arctic Alaska and Siberia Arctic Alaska and Siberia produce smoke produce smoke

•• Occurs in summerOccurs in summer•• Characterized by soluble Characterized by soluble

potassium and organic potassium and organic and elemental carbonand elemental carbon

•• This is a natural This is a natural phenomenon, but recent phenomenon, but recent studies suggest that the studies suggest that the frequency of fires in highfrequency of fires in high-- latitudes is increasing due latitudes is increasing due to climate change.to climate change.

AnthropogenicAnthropogenicRUSALCA Sulfur, Copper and Nickel (0.34 to 1.15 μm)

0

500

1000

1500

2000

2500

3000

3500

6 8 10 12 14 16 18 20 22 24

Day in August, 2004

S C

once

ntra

tion

(ng/

m3)

0.02

0.12

0.22

0.32

0.42

0.52

0.62

0.72

Cu and N

i Concentration

(ng/m3)

S Cu Ni

AnthropogenicAnthropogenic

Aug.

14

Aug.

2

Aug.

8

The trajectories during the middle of the cruise associated with high concentrations of metals and other anthropogenic components accumulate these components in industrial regions in northern Russia, such as Norilsk.

The high levels of these compounds in Nome is a result of diesel generators and other fossil fuel burning equipment in port and on the ship.

Arctic HazeArctic Haze•• Air enters Alaska from Air enters Alaska from

the Arcticthe Arctic

•• Classically, a Classically, a wintertime transportwintertime transport

•• Characterized by Characterized by layers of sulfate, layers of sulfate, metals, polycyclic metals, polycyclic aromatic hydrocarbons aromatic hydrocarbons and light absorbing and light absorbing carbon aerosols from carbon aerosols from industry in Northern industry in Northern Europe and RussiaEurope and Russia

HYSPLIT4 meteorological backwards trajectory for an Arctic Haze event observed at Poker Flat Research Range in Alaska.

Summertime Arctic HazeSummertime Arctic Haze

•• AroundAround--thethe--pole pole transport like transport like wintertime Arctic Hazewintertime Arctic Haze

•• Different aerosol Different aerosol composition and composition and concentrations due to concentrations due to photochemistry, photochemistry, aqueous phase aqueous phase chemistry and different chemistry and different removal mechanismsremoval mechanisms

Aug 12

Jul 3

1

Aug 6

0.340.34--1.15 1.15 μμm S, m S, ClCl, Cu and Ni during a Chinese , Cu and Ni during a Chinese Research Cruise (CHINARE II) to the Research Cruise (CHINARE II) to the ChukchiChukchi and and Beaufort Seas and Arctic Ocean in 2003 Beaufort Seas and Arctic Ocean in 2003 (Cu and Ni are plotted on the secondary axis)(Cu and Ni are plotted on the secondary axis)

0

100

200

300

400

500

600

700

Date

Con

cent

ratio

n (n

g/m

^3)

0

1

2

3

4

5

6

7

8

9

10

S Cl Cu Ni

Aug 8

Aug 19

Aug 31

Sept 1

1

Ship Exhaust Asian EmissionsIndustrial Emissions

0.10.1--0.34 0.34 μμm m ClCl, Zn and Ni at the Poker , Zn and Ni at the Poker Flat Research Range (Spring 2001)Flat Research Range (Spring 2001)

0

4

8

12

3/25

/200

1

3/28

/200

1

3/31

/200

1

4/3/

2001

4/6/

2001

4/9/

2001

4/12

/200

1

4/15

/200

1

4/18

/200

1

4/21

/200

1

Date (m/d/y)

Con

cent

ratio

n (n

g m

-3)

Cl (0.1 to 0.34 um) Zn (0.1 to 0.34 um) Ni (0.1 to 0.34 um)

Meteorological backwards trajectories for these peaks go to Norilsk, Russia.

Meteorological backwards trajectories for this peak goes to the Kola peninsula.

Examples of Arctic Haze and Asian Dust Examples of Arctic Haze and Asian Dust Reaching Interior Alaska (Poker Flat Research Reaching Interior Alaska (Poker Flat Research Range)Range)

0

100

200

300

400

500

3/25

/200

13/

27/2

001

3/29

/200

13/

31/2

001

4/2/

2001

4/4/

2001

4/6/

2001

4/8/

2001

4/10

/200

14/

12/2

001

4/14

/200

14/

16/2

001

4/18

/200

14/

20/2

001

4/22

/200

1

Date (m/d/y)

Silic

on C

once

ntra

tion

(ng

m-3

) )

Si (1.15 to 2.5 um) Si (0.34 to 1.15 um) Si (0.1 to 0.34 um)

Asian Dust EventArctic Haze Event

Asian EmissionsAsian Emissions•• Each spring emissions Each spring emissions

from Asia enter the from Asia enter the Arctic.Arctic.

•• The typical transport The typical transport path crosses the North path crosses the North Pacific Ocean and Pacific Ocean and enters the Arctic from enters the Arctic from the southwest.the southwest.

•• These events are These events are observed in Barrow, observed in Barrow, Alaska, and over the Alaska, and over the Arctic Ocean.Arctic Ocean.

HYSPLIT4 meteorological backwards trajectory for an Asian event observed at Poker Flat Research Range in Alaska.

Asian EmissionsAsian Emissions

•• The Asian emissions The Asian emissions are characterized by are characterized by soil elements from the soil elements from the Gobi and Gobi and TaklimakanTaklimakan Deserts.Deserts.

•• The emissions include The emissions include metals, sulfur and metals, sulfur and other compounds from other compounds from industrial sources industrial sources along the transport along the transport path.path.

The Taklimakan Desert, China

Image courtesy of Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC

Difficulty in Determining Sources of Difficulty in Determining Sources of Contaminants in ArcticContaminants in Arctic•• Contaminants, once they Contaminants, once they

reach the Arctic, remain in reach the Arctic, remain in the Arctic air mass for a the Arctic air mass for a long time and travel long long time and travel long distances.distances.

•• So, unless there is a very So, unless there is a very specific and consistent specific and consistent signature for a source, the signature for a source, the best way to identify the best way to identify the sources of the sources of the contaminants in the Arctic contaminants in the Arctic is to characterize them as is to characterize them as they enter the Arctic.they enter the Arctic.

Aug 13

Aug 1

Aug 7

SummarySummary•• The results from RUSALCA show that the The results from RUSALCA show that the

aerosols over the Bering and aerosols over the Bering and ChukchiChukchi Seas Seas are:are:–– Present in low concentrations (<1 Present in low concentrations (<1 μμg mg m--33))–– Predominantly sea saltPredominantly sea salt–– Influenced by strong, episodic aerosol plumes Influenced by strong, episodic aerosol plumes

from sources both natural and anthropogenicfrom sources both natural and anthropogenic•• These results are consistent with results These results are consistent with results

from other cruises and groundfrom other cruises and ground--based based experimentsexperiments

SummarySummaryThe implications from these results are:The implications from these results are:

–– The deposition of pollutants and nutrients in the The deposition of pollutants and nutrients in the Arctic in summer will depend on where the pollutant Arctic in summer will depend on where the pollutant plumes cross the Arctic and will not be spatially or plumes cross the Arctic and will not be spatially or temporally homogeneous temporally homogeneous

–– The primary aerosols causing summertime direct The primary aerosols causing summertime direct aerosol radiative forcing effects are contained in aerosol radiative forcing effects are contained in transient plumestransient plumes

–– There is enough sulfate available in many of the There is enough sulfate available in many of the aerosol plumes to cause cloud nucleation and indirect aerosol plumes to cause cloud nucleation and indirect aerosol radiative forcing effectsaerosol radiative forcing effects

Future WorkFuture Work•• Perform calculations using the RUSALCA data to Perform calculations using the RUSALCA data to

estimate aerosol deposition and radiative estimate aerosol deposition and radiative impacts in the Arcticimpacts in the Arctic

•• Collect additional aerosol samples during future Collect additional aerosol samples during future cruises to try to establish an aerosol baseline cruises to try to establish an aerosol baseline and observe any aerosol trends over the Bering and observe any aerosol trends over the Bering and and ChukchiChukchi SeasSeas

•• Establish additional groundEstablish additional ground--based sites around based sites around the Arctic to quantify the high temporal and the Arctic to quantify the high temporal and spatial variability of the aerosol plumes observed spatial variability of the aerosol plumes observed during RUSALCA and other experimentsduring RUSALCA and other experiments