Pathways for North American Outflow - Hindcast for ICART2

Qinbin Li, Daniel J. Jacob, Rokjin Park, Colette L. Heald, Yuxuan Wang, Rynda Hudman, Robert M. Yantosca

Harvard University

Mian ChinNASA/GSFC

with support from NOAA Atmospheric Chemistry Program

ICART2 Planning Meeting, 1/21/2004NOAA Aeronomy Lab, Boulder, CO

Model Simulations

GEOS-CHEM

• Global 3-D model of tropospheric chemistry-aerosols. • Driven by GMAO GEOS-3 assimilated meteorology.• Used in TRACE-P and ITCT-2K2 chemical hindcasts / forecasts and post-mission analyses.

Model Simulations

• Time period: June-August of 1998, 2000, 2001, 2002• Tagged CO (all four years): 2°x2.5° (use 1998 FF and climatological BB emissions for all four years)• Full-chemistry (2000 only): 1°x1° ‘nested’ over North America (use 2000 BB emissions)

Observations

• MOPITT CO column• MODIS aerosol optical depth• AERONET aerosol optical depth

Summer 2004: El Niño, La Niña, or Neutral?

Most of the statistical and dynamical model forecasts are indicating

slightly above-average conditions over the coming several months.

The most recent Niño 3.4 SST anomalies fall in the range of near-neutral conditions.

GEOS-3 750 hPa Winds, 2000

H

H

H

H

Zonally-uniform flow pattern in June, while curve-like flow patterns in July and August.

El Nino influence lasted into June; outflow in June at lower latitudes than other years.

HH

HH

GEOS-3 750 hPa Winds, 1998

GEOS-3 500 & 300 hPa Winds

Recirculation in the middle to upper troposphere.

500 hPa

H

H

Recirculation in the middle and upper troposphere.

300 hPa

H

H

North American Emissionsunit: 10-12 molec/cm2/s FF BB, June

BB, July BB, AugustClimatology

Climatology: extensive boreal forest fires.

BB, July 2000 BB, August

2000: huge forest fires in NW (Montana, Idaho, Wyoming, etc.)

Duncan et al. [2003]

FF outflow at 35ºN-50ºN, BB outflow 45ºN-55ºN. Outflow at much lower latitudes in June 1998.

Horizontal N. American CO Flux, June

2000

1998

July

Outflow in July is at lower latitudes than in June.Outflow in August shows features in between June and July.

Horizontal N. American CO Flux, 2000

August

Vertical and Zonal N. American CO Flux, June

300 hPa 70ºW

70ºW 70ºW

(1) BL and lower FT outflow.(2) Convective outflow in MT/UT.

20001998

Lines – fluxes (vertical: 10-12 moles cm-2 s zonal: 10-9 moles cm-2 s) Color contours – concentrations (ppb)

Vertical and Zonal N. American CO Flux, July

Stronger convective transport than June and August.

300 hPa

70ºW

70ºW

70ºW

Lines – fluxes (vertical: 10-12 moles cm-2 s zonal: 10-9 moles cm-2 s) Color contours – concentrations (ppb)

Vertical and Zonal N. American CO Flux, August

70ºW

300 hPa 70ºW

70ºW

Lines – fluxes (vertical: 10-12 moles cm-2 s zonal: 10-9 moles cm-2 s) Color contours – concentrations (ppb)

Event June 9-13: BL, WCB and Convective Outflow

GOES IR

AERONET

Event June 9-13: WCB, Convection

from Midwestfrom southeast

Event July 2-7: Outflow at Low Latitude

GOES IR

AERONET

Event July 2-7: Outflow at Low Latitude

Enhanced ozone and aerosols.Enhanced CO.

Recirculation in the Upper Troposphere

Deep convection in the south-central U.S. followed by recirculation in the MT and UT; fairly aged air masses with high ozone but depleted NOy and aerosols upon leaving the continental U.S.

North American Fossil Fuel CO270 hPa, July 6-23, 2000

(animation)

Event July 9-14: Recirculation

GOES IR

AERONET

Event July 9-14: Recirculation

Enhanced CO in the upper troposphere.

Enhanced ozone in the upper troposphere.

Asian and European Influences Detectable?

• Asian and European influences dispersed into the background.

• Asian plumes could be seen in strong transpacific transport.

> 40 ppbv

N. American Biomass Burning CO, 500 hPaAugust 2000

Plumes from the huge fires in the northwest US are lifted to 5-8 km by convection and then exported

(1) northeastward north of 50ºN

(2) eastward by the westerly at 40-50ºN

(3) southeastward at 30-45ºN and impacts much of the middle and east U.S.

(animation)

N. American Fossil Fuel CO, 850 hPa July, 2000

N. American Fossil Fuel CO, 500 hPa July, 2000

N. American Fossil Fuel CO, 300 hPa July, 2000

Summary and Conclusions

• Main pathways: BL and lower FT outflow; Convective outflow in the MT and UT.

• Outflows occur at a rather large latitude range (30ºN-55ºN) along the east coast.

• Deep convections in the south-central U.S. are often followed by recirculation in the MT and UT over much of the U.S.

• Biomass burning outflows generally occur at higher latitudes (45ºN-55ºN) than anthropogenic outflows.

• Outflows occur at lower latitudes in July and August than in June due to more curve-like flow patterns in July and August.

• MOPITT CO columns and MODIS and AERONET aerosol optical depths provide useful insights in understanding N. American pollution outflow.