Long-range transport of ozone from the Los Angeles Basin: A case study

Long-range transport of ozone from the Los Angeles Basin:

A case study

A.O. Langford1, C. J. Senff2, R.J Alvarez1 II, R. M. Banta1, R.M. Hardesty1

1Chemical Sciences Division, Earth System Research Laboratory,

NOAA, Boulder, Colorado, USA

2Cooperative Institute for Research in Environmental Sciences,

University of Colorado, Boulder, and Chemical Sciences Division, Earth System Research Laboratory, NOAA, Boulder, Colorado, USA

Pre-CalNex flights coincided with highest ozone in SCAB

during all of 2009

27 of 31 days in July exceeded NAAQS in South Coast Air Basin

2009 High ozone episode15 July: 1-hr 116 ppbv 8-hr 100 ppbv

2009 High ozone episode16 July: 1-hr 124 ppbv 8-hr 90 ppbv

2009 High ozone episode17 July: 1-hr 149 ppbv 8-hr 111 ppbv

2009 High ozone episode18 July: 1-hr 150 ppbv 8-hr 128 ppbv*

* 2009 high value

2009 High ozone episode19 July: 1-hr 146 ppbv 8-hr 110 ppbv

2009 High ozone episode20 July: 1-hr 115 ppbv 8-hr 83 ppbv

San Gabriel Mountains from Pomona CA (1910)

Twin Otter over San Gabriel Mountains on 17 July 2009

Flight track 17 July 2009

TOPAZ Aerosol 17 July

TOPAZ Ozone 17 July

TOPAZ Ozone 17 July

Fontana

San Gabriel Mountains

Glendora

Chino Hills

Santa Ana MountainsCosta Mesa

TOPAZ Ozone 17 July 2009

4

3

2

1

0

120100806040200

Distance (km)

(b)

UCLA SMOG Model 27 Aug 1987 SCAQSLu and Turco 1996

4

3

2

1

0

120100806040200

Distance (km)

(a)

UCLA SMOG ModelLu, Turco, and Jacobson 1994-1996

Integrated model with:• Mesoscale meteorology• Boundary layer physics• Tracer advection• Convection and diffusion• Photochemistry• Aerosol microphysics and chemistry• Solar and terrestrial radiative transfer

UCLA SMOG ModelLu, Turco, and Jacobson 1994-1996

• 85 x 55 grid cell meteorological domain• 51 x 31 grid cell tracer chemistry domain • Horizontal resolution ~0.05° (~5 km)• 20 non-uniform vertical layers

Synoptic Background

00 UT 18 July 200944

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

44

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

1000 hPa 1000 hPa

m ASL

00 UT 27 August 1987

1000 hPa

Synoptic Background

44

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

700 hPa 700 hPa

m ASL

00 UT 18 July 2009 00 UT 27 August 1987

700 hPa

Where does the ozone go?48 h HYSPLIT forward trajectories

44

42

40

38

36

34

32

-125 -120 -115 -110 -105Longitude (°E)

2000 m 3000 m 4000 m

DV

GB

CL

GCMV

GH

(a)

Where does the ozone go?48 h HYSPLIT forward trajectories

6

4

2

0

00:007/18

12:00 00:007/19

12:00 00:007/20

UT

2000 3000 4000

Where does the ozone go?48 h HYSPLIT forward trajectories

70

65

60

55

50

45

40

35

7/15 7/17 7/19 7/21

UT

GB

24 hours later

Where does the ozone go?48 h HYSPLIT forward trajectories

70

65

60

55

50

45

40

35

7/15 7/17 7/19 7/21

UT

MV CL

48 hours later

Where does the ozone go?48 h HYSPLIT backward trajectories

44

42

40

38

36

34

32

-125 -120 -115 -110 -105Longitude (°E)

CL

21 20 19 18 17 16 15

Where does the ozone go?48 h HYSPLIT forward trajectories

6

4

2

0

7/15 7/17 7/19 7/21

UT

How often does this occur?

What about 19 July 2009

Flight track 19 July 2009

TOPAZ Aerosol 19 July

TOPAZ Ozone 19 July

Synoptic Background

00 UT 18 July 2009 00 UT 20 July 200944

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

44

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

1000 hPa 1000 hPa

m ASL

00 UT 090720 1000 hPa

1000 hPa

Synoptic Background

00 UT 18 July 2009 00 UT 20 July 200944

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

44

42

40

38

36

34

32

30

-125 -120 -115 -110 -105

Longitude

700 hPa 700 hPa

m ASL

700 hPa

700 hPa

Questions for CalNex

• What conditions are needed for “Mountain Chimney Effect”?

• What conditions favor long range transport from the Los Angeles Basin?

• How well can WRF/Chem reproduce these observations?