DC8 photo of Mexico City by Cameron McNaughton, University of Hawaii , Feb 2006

Characterizing Megacity Pollution and Its Regional

Impact with TES Measurements

Changsub Shim, Qinbin Li, Ming Luo, Susan Kulawik, Helen Worden, and Annmarie Eldering

The Jet Propulsion LaboratoryCalifornia Institute of Technology

Pasadena, California

3rd GEOS-Chem User’s Meeting

Mapping pollution outflow using OMapping pollution outflow using O33-CO -CO

correlationcorrelation

The observed OThe observed O33-CO relationship has been used to characterize continental -CO relationship has been used to characterize continental pollution outflow [pollution outflow [Fisherman and SeilerFisherman and Seiler, 1983; , 1983; Chameides et alChameides et al., 1987; ., 1987; Parrish et alParrish et al., 1993, etc.].., 1993, etc.].

Positive OPositive O33-CO correlations and ∆O-CO correlations and ∆O33/∆CO indicate photochemical O/∆CO indicate photochemical O33 productions. productions.

Tropospheric Emission Spectrometer (TES) aboard the Aura satellite Tropospheric Emission Spectrometer (TES) aboard the Aura satellite provides concurrent Oprovides concurrent O33 and CO retrievals and and CO retrievals and vertical profiles.vertical profiles.

TES OTES O33-CO correlation (at 618 hPa) has been used to map global -CO correlation (at 618 hPa) has been used to map global continental pollution outflow [continental pollution outflow [Zhang et alZhang et al., 2006]. ., 2006].

ObjectivesObjectives

Can we characterize megacity pollution and its regional impactCan we characterize megacity pollution and its regional impact with TES with TES tropospehric ozone and CO retrievals?tropospehric ozone and CO retrievals?

We analyzed TES OWe analyzed TES O33 and CO data over the Mexico City Metropolitan Area and CO data over the Mexico City Metropolitan Area

(MCMA) and Southern U.S. (15-30°N and 90 - 105°W) during the (MCMA) and Southern U.S. (15-30°N and 90 - 105°W) during the MILAGRO/INTEX-B campaign (March 2006).MILAGRO/INTEX-B campaign (March 2006).

We first compared TES OWe first compared TES O33 and CO retrievals with those from airborne and CO retrievals with those from airborne

measurements (C130 & DC8 flights) during this campaign.measurements (C130 & DC8 flights) during this campaign.

The comparisons of OThe comparisons of O33-CO correlation between airborne measurements, -CO correlation between airborne measurements,

TES retrievals, and GEOS-Chem model were then used to evaluate the TES retrievals, and GEOS-Chem model were then used to evaluate the TES capability to characterize urban outflow on a regional scale.TES capability to characterize urban outflow on a regional scale.

Mexico City Metropolitan Area (MCMA) (19°N, 99°W)Mexico City Metropolitan Area (MCMA) (19°N, 99°W)

22ndnd largest metropolitan area in the world (~20 largest metropolitan area in the world (~20 million inhabitants) within area of ~1,500 kmmillion inhabitants) within area of ~1,500 km22..

MCMA is surrounded by mountains and thermal MCMA is surrounded by mountains and thermal inversions often trap pollution within the basin.inversions often trap pollution within the basin.

The elevation (~750 hPa) is about 2.2 km above The elevation (~750 hPa) is about 2.2 km above mean sea level.mean sea level.

Lower pOLower pO22 makes combustion ineffective, makes combustion ineffective,

which enhances emissions of CO, VOCs, and Owhich enhances emissions of CO, VOCs, and O33..

Motor vehicular exhaustion is a very important Motor vehicular exhaustion is a very important source of air pollution (3 million aged vehicles).source of air pollution (3 million aged vehicles).

In-situ measurements during MILAGRO/INTEXB In-situ measurements during MILAGRO/INTEXB (C130 and DC8 )(C130 and DC8 )

NSF C-130 for MILAGRO covers NSF C-130 for MILAGRO covers (16 – 25°N and 93 – 101°W) in Mar (16 – 25°N and 93 – 101°W) in Mar 2006 (red).2006 (red).

NASA DC-8 for INTEX-B covers (15 NASA DC-8 for INTEX-B covers (15 – 35°N and 90 - 103°W) (blue).– 35°N and 90 - 103°W) (blue).

~6,000 coincident measurements of ~6,000 coincident measurements of OO33 and CO from the two aircrafts (5- and CO from the two aircrafts (5-min merge).min merge).

On-board the Aura satellite launched in July 2004 to provide On-board the Aura satellite launched in July 2004 to provide simutaneous 3-D mapping of tropospheric Osimutaneous 3-D mapping of tropospheric O33, CO, HDO and , CO, HDO and CHCH44

, , amongamong other species globally.other species globally.

The Aura satellite moves in polar sun-synchronous orbit at 705 The Aura satellite moves in polar sun-synchronous orbit at 705 km height in the ascending node passing equator at 0145 and km height in the ascending node passing equator at 0145 and 1345 LT (16 days for global coverage).1345 LT (16 days for global coverage).

TES has a spatial resolution of 5 x 8 km in nadir-viewing TES has a spatial resolution of 5 x 8 km in nadir-viewing mode. mode.

TES has the standard observations (“global surveys”: 108 km TES has the standard observations (“global surveys”: 108 km apart along the track) and the special observations (“step and apart along the track) and the special observations (“step and stares”) with denser nadir coverage (45 km apart).stares”) with denser nadir coverage (45 km apart).

11 step and stares and 5 global surveys were used in this 11 step and stares and 5 global surveys were used in this study for the MILAGRO/INTEX-B periods. study for the MILAGRO/INTEX-B periods.

Version 2 data (V002, F03_03) with better quality flags.Version 2 data (V002, F03_03) with better quality flags.

TES retrievalsTES retrievals

TES orbital tracks over MCMA TES orbital tracks over MCMA during MILAGRO/INTEX-Bduring MILAGRO/INTEX-B

Typical TES O3 and CO Averaging Kernel

Step and stare Mar 12th , 2006.

GEOS-Chem simulationsGEOS-Chem simulations GEOS-4 met fields (2x2.5° with 30 layers) from NASA GMAO.GEOS-4 met fields (2x2.5° with 30 layers) from NASA GMAO.

Standard full chemistry simulations (OStandard full chemistry simulations (O33-NOx-VOC) [version 7- 04 -10].-NOx-VOC) [version 7- 04 -10].

Monthly biomass burning emission inventory [Monthly biomass burning emission inventory [Duncan et alDuncan et al., 2003].., 2003].

Fossil fuel emission inventory: EDGAR inventory scaled for time and the model grid Fossil fuel emission inventory: EDGAR inventory scaled for time and the model grid [[Benkovitz et alBenkovitz et al., 1996; ., 1996; Bey et alBey et al., 2001]. EPA/NEI 99 and BRAVO inventories [., 2001]. EPA/NEI 99 and BRAVO inventories [U.S. U.S. EPA,EPA, 2004; 2004; Kuhns et alKuhns et al., 2005] are used for U.S. and Mexican fossil fuel emissions ., 2005] are used for U.S. and Mexican fossil fuel emissions respectively.respectively.

Lightning NOx emissions with parameterization based upon cloud top height and Lightning NOx emissions with parameterization based upon cloud top height and regionally scaled to OTD/LIS observations.regionally scaled to OTD/LIS observations.

Biogenic emissions: MEGAN inventory [Biogenic emissions: MEGAN inventory [Guenther et alGuenther et al., 2006].., 2006].

3-hour O3-hour O33 and CO model results were sampled along TES orbits. and CO model results were sampled along TES orbits.

For comparison with TES retrievals, local TES averaging kernels were applied to For comparison with TES retrievals, local TES averaging kernels were applied to GEOS-Chem vertical profiles [GEOS-Chem vertical profiles [Zhang et alZhang et al, 2006]., 2006].

Observed (in-situ) vertical distributions of OObserved (in-situ) vertical distributions of O33, ,

CO, and NOx (Mar. 2006)CO, and NOx (Mar. 2006)

Altitude ofMCMA !

O3 NOxCO

MCMA pollution outflow concentrated at 600-800 hPa.TES has large sensitivity to 600 – 800 hPa pressure levels. TES data are ideal for analyzing the MCMA outflows!

Comparisons of OComparisons of O33 over the MCMA (Mar. 2006) over the MCMA (Mar. 2006)

There is considerable O3 enhancement in the in situ data at 600 – 800 hPa over MCMA. The enhancement is not apparent in TES data nor GEOS-Chem results.

Comparisons of CO over the MCMA (Mar. 2006)Comparisons of CO over the MCMA (Mar. 2006)

The CO enhancement in aircraft data over MCMA at 600 – 800 hPa is not apparent in TES retrieval nor GEOS-Chem results. Why?

Time series (daily) comparisons over the MCMA (C130 & DC8 coverage gridded in 2 x 2.5°) between 600 – 800 hPa

C130+DC8

GC raw

TES (co-located)

TES (all)

TES orbit did not cover the MCMA for the days of three high pollution events (Mar. 9th, 22th, and 29th.).

But the TES data generally show good agreements with aircraft measurements.

The GEOS-Chem model underestimates both O3 and CO by ~29% and ~45% respectively (at 600 – 800 hPa).

OO33-CO correlations and ∆O-CO correlations and ∆O33/∆CO between Aircraft, TES, and GEOS-/∆CO between Aircraft, TES, and GEOS-

Chem over MCMA and surrounding regions.Chem over MCMA and surrounding regions.

All results are gridded in 2 x 2.5° and sampled along with aircraft measurements.

The O3-CO correlation derived from TES data is in good agreement with those from in situ and GEOS-Chem/AK resuts, reflecting significant O3 production and transport over the MCMA and surrounding regions.

Height Height (hPa)(hPa) RR ∆∆OO33/∆CO/∆CO

MCMA in-situMCMA in-situ 600 – 600 – 800800 0.780.78 0.280.28

MCMA TESMCMA TES 600 - 600 - 800800 0.50.5 0.430.43

MCMA CTMMCMA CTM 600 - 600 - 800800 0.580.58 0.250.25

INTEX-NAINTEX-NA Surf - Surf - 600600

0.5 – 0.5 – 0.70.7

0.31 -0.31 -0.440.44

US (US (Parrish et Parrish et alal))

SurfSurf 0.820.82 0.330.33

US (US (Chin et Chin et alal))

SurfSurf 0.7 – 0.7 – 0.90.9 ~ 0.3~ 0.3

TRACE-PTRACE-P Surf - Surf - 600600 0.60.6 0.150.15

ICARTT ICARTT ((Zhang et alZhang et al))

618618 0.340.34 0.720.72

Conclusions

The pollution outflow from the MCMA and the surrounding regions during MILAGRO/INTEX-B were characterized with aircraft observations, TES tropospheric O3 and CO retrievals, and GEOS-Chem results.

The aircraft observations show significant enhancement of O3, CO, and other chemical species at 600 – 800 hPa, reflecting pollution outflow from the MCMA. The observed vertical distributions over the MCMA are not apparent in TES O3 and CO retrievals due in part to the limited coverage missing three high pollution events. However, the TES data shows fairly good agreements with the aircraft measurements on a daily basis.

The O3-CO correlations derived from TES data are in good agreement with those derived from aircraft observations and GEOS-Chem results (r: 0.5 – 0.9; ∆O3/∆CO: 0.3 – 0.5), reflecting significant O3 production and transport over the MCMA and surrounding regions.

TES data provides valuable information to capture regional scale pollution outflows and we may extend this analysis to global-scale study.