Inter-annual Variations of AirInter-annual Variations of Air

Mass Transport to the ArcticMass Transport to the Arctic

Dr. Sunling GongDr. Sunling Gong

Science and Technology Branch

Environment Canada

January 8, 2007

AlertBarrow

2

Observed Temporal Variation for Sulphate

J M M J S N J

1

2

3

10

10

10

Measured aerosol sulphate at Alert (1980--1995)

(Sirois and Barrie, 1999)

)

/

](

[

3

2 4

m

ng

SO

!

1980 1985 1990 1995 2000

1

2

3

10

10

10

IC_SO4= ( ng/m3 )

3

How to model the seasonal changes

and trends?

Emissions surrounding the Arctic.

Removal patterns – e.g.

precipitation changes

Transport patterns.

4

Trajectory Model:HYSPLIT4 (NOAA Air Resources Laboratory)

Trajectory duration: 10-day backward

Arriving at Alert (Barrow)82.31 N, 62.31 W (71.32 N, 156.6 W)

1000 m above sea level

12 times a day for 1989-2000 (1988-1998)

Clustering TechniqueBased on Dorling’s Algorithm (Dorling et al., 1992)

Modified to handle a large number oftrajectories

Trajectory Calculations

5

Wintertime Transport Patterns for 1981-2000

2480 trajectories in total;

Best grouped into 7

clusters;

Clusters 1, 2, and 6

account for ~40% of the

overall air mass transport;

The interannual variability

of transport patterns were

obtained by counting the

number of trajectories

from each year.

6

Cluster-mean plots for the four mid-season

Jan Apr

Jul Oct

7

Inter-annual Variations for Jan.

Year

1980 1985 1990 1995 2000

% C

ontrib

utio

ns

0

10

20

30

40

50

Cluster 1

Cluster 2

Cluster 6

8

Correlation between Transport Frequency and

Black Carbon Concentration

Jan-90Jan-91Jan-92Jan-93Jan-94Jan-95Jan-96Jan-97Jan-98Jan-99Jan-00

100

150

200

250

300

350

400

BC (ng/m3)

Freq. (1+2+6)

BC

co

nce

ntr

atio

n (

ng

/m3

)

0

10

20

30

40

50

60

70

80

Fre

qu

en

cy (c

luste

rs 1

, 2, a

nd

6)

R1=0.97 R2=0.61

9

Transport Frequency ~ NAO/AO Indices

at Alert

0o

60oE

75oN

4 (9.1%)

2 (5.0%)

3 (6.0%)

5 (6.4%)

1 (4.6%)

Alert

Eurasia

Greenland

Iceland

Canada

0.2710.697Clusters 4+5

-0.626-0.677Clusters 1+2+3

0.0700.570Cluster 5

0.2870.429Cluster 4

-0.655-0.485Cluster 3

-0.301-0.249Cluster 2

-0.169-0.545Cluster 1

NAOAOCorrelation (R)

10

Transport Frequency ~ NAO/AO Indices

at Barrow

0.9420.825Clusters 5+6

0.4330.307Cluster 6

0.7250.682Cluster 5

-0.9000.411Cluster 4

0.110-0.482Cluster 3

-0.906-0.751Cluster 2

-0.410-0.718Cluster 1

NAOAOCorrelation (R)

11

Variations in BC Emissions

Black Carbon, Canada

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

180,000

200,000

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

BC

(t)

30%

12

Questions:

Which is the dominant factor in modeling the

observed spatial and temporal distributions of

pollutants?

Transport variations

Removal processes

Emissions