Transport of Pollution over Mexico and the Gulf of Mexico: - - PowerPoint PPT Presentation

Transport of Pollution over Mexico and the Gulf of Mexico: Preliminary Results from MILAGRO Campaign

MILAGRO Science Team

TF HTAP / NAS / AC&C Workshop Washington, DC June 9-13, 2008

• Air pollution in megacities and large urban complexes
• Air Quality in the Mexico City Metropolitan Area
• MCMA 2002/2003 Field Measurement Campaign
• MILAGRO Field Measurement Campaign
• Preliminary Results

Outline of Presentation

The Urban and Rural Population of the World (1950-2030)

Source: UN Population Division, World Urbanization Prospect: The 2005 Revision (2006).

The global proportion of urban population increased from 29% in 1950 to 49% in 2005 and is projected to reach 60% by 2030. 80% will be living in the less developed regions.

4.9 billion 3.2 billion 8.1 billion

MEGACITIES (> 10 Million inhabitants) 1950 – 2 (New York City, Tokyo) 2000 – 20 Cities with 1 million inhabitants 2000: > 300 Asia and Africa: fastest growing urban centers

20 Megacities of the World

City 2005 1 Tokyo 35.2 2 Mexico City 19.4 3 New York 18.7 4 São Paulo 18.3 5 Mumbai 18.2 6 Delhi 15.0 7 Shanghai 14.5 8 Kolkata 14.3 9 Jakarta 13.2 10 Buenos Aires 12.6 11 Dhaka 12.4 12 Los Angeles 12.3 13 Karachi 11.6 14 Rio de Janeiro 11.5 15 Osaka-Kobe 11.3 16 Cairo 11.1 17 Lagos 10.9 18 Beijing 10.7 19 Manila 10.7 20 Moscow 10.7

Source: UN Population Division, World Urbanization Prospect: The 2005 Revision (2006).

Urbanization: Local, regional, and global impacts

Urban Regional Global Increased energy usage in urban areas including motor vehicles and industrial activities leads to high levels of emissions.

• Urban air quality

degradation;

• both chronic and acute

health effects;

• visibility reduction.

Pollutants emitted from urban areas can react in sunlight to form other products downwind of the cities.

• acid deposition;
• ecosystem degradation;
• changes in regional

climate. Global Impacts trace gases and aerosols can lead to weather modification and global climate change.

Topographical Map of Mexico City Metropolitan Area showing the Urban Expansion

• Population Growth

>18 million (2000): 20-fold increase since 1900

• Urban Sprawl

>1500 km2 (2000): 10-fold increase since 1960 >Expansion to peripheral areas

• Geographic and Topographical

Conditions >High altitude (2240m): less efficient combustion processes >Mountains are a physical barrier for winds >2nd largest megacity in the world >Temperature inversions in the dry season

• Increases in Emissions Sources

Source: L.T. Molina and M.J. Molina, ed., Air Quality in the Mexico Megacity: An Integrated Assessment, Kluwer Publishers, 2002.

(a): Measured OH in MCMA (solid line) and in NYC (plusses); (b): measured HO2 in MCMA (solid line) and NYC (plusses). Gray dots are individual MCMA measurements. (a): Median ozone in MCMA 2003 (solid line) and NYC 2001 (plusses). (b): Median NOx in MCMA 2003 (solid line) and NYC 2001 (plusses). Gray dots are individual MCMA measurements. (c): Median VOCs from 4 sites in MCMA 2003 (solid line) and NYC 2001 (plusses).

Diurnal Variation of some photochemical variables from MCMA-2003 Campaign

Source: Shirley, T. R., Brune, W. H., Ren, X., Mao, J., Lesher, R., Cardenas, B., Volkamer, R., Molina, L. T., Molina, M. J., Lamb, B. , Velasco, E. , Jobson, T., Alexander, M.: Atmospheric oxidation in the Mexico City Metropolitan Area (MCMA) during April 2003, Atmos. Chem. Phys., 6, 2753-2765, 2006.

Classification of MCMA-2003 Meteorological Events

(three basin flow patterns and different synoptic scales) Cold Surge O3-North O3-South GOES-12 Basin Schematic

(Source: de Foy et al., 2006)

MILAGRO Campaign

Megacity Initiative: Local And Global Research Observations First international scientific collaborative project to examine the behavior and the export of atmospheric pollutants generated in magacities. Scientific Goals:

• What is the temporal and spatial extent of pollution

plumes from megacities?

• How and where are urban pollutants removed from the

atmosphere?

• What are the regional and global impacts of urban

plumes?

• Representative tropical megacity
• Extensive air quality monitoring network, good meteorology

support, emissions inventories and infrastructure

• Excellent scientific collaborations
• Previous Campaign: MCMA-2003
• Surface gas and aerosol measurements at supersite and

using mobile labs

• Plenty of aerosol from representative area - large signal
• High photochemical activity to maximize chemical changes
• Significant organics to look at secondary organics aerosols
• Ground and aircraft operations – downwind sites

MILAGRO Case Study: Why Mexico City?

MCMA-2006 (Mexico City Metropolitan Area – 2006)

• examine emissions and boundary layer concentrations within México City;
• study the exposure patterns and effects on human health;
• evaluate policies to reduce pollutant levels.

MAX-Mex (Megacity Aerosol Experiment – Mexico)

• examine the properties and evolution of aerosols and gas-aerosol interactions

in the immediate urban outflow. MIRAGE-Mex (Megacity Impacts on Regional & Global Environments – Mexico)

• examine the evolution of the México City plume on larger regional scales.

INTEX-B (Intercontinental Chemical Transport Experiment –Phase B)

• study the transport, transformation and impacts of aerosols and gases on air

quality and climate from local to global scales. Inter-comparison of observations among multiple ground-based, airborne and satellite platforms in order to generate a comprehensive integrated data set. The overall Campaign is supported by forecasts from meteorological and chemical models and surface network.

MILAGRO Campaign: Four coordinated components

MILAGRO Campaign: Four Coordinated Components Geographic Coverage

MCMA-2006

Supersites, Moblle Laboratories (MCE2)

San Francisco Miami Atlanta

• St. Louis

Guatemala San Salvador Tegucigalpa Managua

INTEX-B

NASA DC-8

J-31, Satellites (NASA) MIRAGE-Mex

NSF C-130, King Air, Supersite (NCAR)

MAX-Mex

DOE G-1, King Air, Supersite (DOE ASP)

San José Havana Los Angeles El Paso Ciudad Juárez San Diego, Tijuana Monterrey Guadalajara

Houston

Dallas

Mexico City

Veracruz

Designed by M. Zavala

MCMA-2006: Ground-Based Measurement Sites

Supersites (T0, T1, T2) SIMAT (Flux Tower) CENICA Tula (refinery, power plant) Naucaplan (industrial zone) RAMA (36 monitoring stations) Mobile units (9 stations) Mobil Labs

• ARI Mobile Lab
• U. Iowa (Lidar)
• Chalmers (DOAS)

Ultralight airplane Paso de Cortes AOT Network

T0: Instituto Mexicano del Petróleo, DF

• Bldg. 20
• Bldg. 27
• Bldg. 33
• Bldg. 32

Wind Profiler

• Bldg. 31

T1: Universidad Tecnológica de Tecámac, EM Supersite of MIRAGE-Mex: examine outflow of urban plume T2: Rancho La Bisnaga (near Tizayuca, Hidalgo) Supersite of MAX-Mex: study the evolution of aerosols

MILAGRO Campaign: Supersites

T0, T1,T2: transport of urban plume to different points in space & time.

T0: IMP Supersite of MCMA-2006, equipped with instruments to measure gases, aerosols, radiation and meteorological parameters to characterize the emissions of pollutants from the urban area

MILAGRO: Aircraft Measurements

(Intercomparison, coordinated flights, sharing of data)

NASA DC-8 Twin Otter NSF/NCAR C-130 DOE G-1 King Air J-31 DC-8: Based in Houston, Texas - Study pollution throughout the Gulf

• f Mexico region at altitudes from

near the surface to 10 km; help improve satellite observations. 5 aircraft based in Veracruz To study:

• pollution in the region
• ver Mexico City, the

rise of pollution from the surface, and its spread into the region;

• effects of aerosol

particles on visibility, sunlight, and climate;

• fires

Ultralight plane (IMK-IFU)

• 1. Observed highly

inhomogeneous spatial distributions of emissions

Mobile Emissions in the MCMA using MCMA/2003 and MCMA/2006 Observations

• 3. Measured reduction of VOC

emission ratios in Mexico City

• 2. On-road

measurement technique for the validation of the Emissions Inventory

0.0 0.1 1.0

H2CO CH3CHO Benzene Toluene C2- Benzene C3- Benzene

ppb/ppm

2003 2006

Zavala et al. , 2007

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VOC Abundance and Reactivity in Mexico City C-130 Overflights

VOC KOH Reactivity

Acetaldehyde Formaldehyde Propanal Methanol *Ethene *Propane Butane Toluene Ethanol Butanal *Propene i-Pentane *Ethyne Pentane i-Butane MTBE Acetone MEK *Ethane Benzene

% OH Reactivity

5 10 15 20 25 30

Apel et al., AGU’07 * designates UCI measurement

VOC Abundance

Methanol *Propane Formaldehyde Acetone Acetaldehyde *Ethyne Butane Ethane Ethanol *Ethene Toluene Propanal i-Pentane i-Butane MEK Acetonitrile Pentane MTBE Benzene Butanal *Propene

Concentration pptv

2000 4000 6000 8000

High methanol ~60% of reactivity from aldehydes

Total Observed Organic Carbon

18 Heald et al., ACP 2008

MCMA-2006: Photochemistry and SOA Formation

Coordinated G1 - C130 - CMET Balloon Flights

Longitude

• 102
• 100
• 98
• 96
• 94
• 92

Latitude

18 20 22 24 26 28

Balloon A Balloon B MCMA

Veracruz

G1: March 18

14:20 - 15:20 CST

C130: March 19

16:00 - 18:00 CST

WRF simulation of Mexico City plume on 19 March: strong southwesterly winds carried pollutants from MCMA towards coastal Mexico-Texas border.

On 18 March, the G-1 sampled air near Mexico City and two CMET balloons were launched from near T1. On 19 March, the C-130 intercepted the plume and the balloon trajectories in the Gulf of Mexico.

CMET balloon – remote controlled (Winds, T, P, RH)

O3 Production in Mexico City Plume during MILAGRO Campaign

CO (ppbv)

100 200 300 400 500

Ox (ppbv)

20 40 60 80 100 120

G1: March 18 C130: March 19

In 1-day-old plume

CO and Ox (O3 + NO2) decrease because of mixing with cleaner air; but Ox/CO increases, indicating continuing Ox production during the plume export.

O3 - Greenhouse Gas

Zavari et al., 2007

G-1 sampled the air near Mexico City on March 18; while C-130 intercepted the plume about 1000 km downwind on March 19. Regional and global climate impacts

O3 Production Efficiency Increases Down-wind

O3 + NO2 produced per NOx consumed, C-130 flights

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Free trop, marine ~ 8.5 Industrial plume ~ 4.5 Free trop, continental ~ 5.9 Polluted BL ~ 5.3

Shon , Madronich, Song, Flocke, Knapp, Anderson, Shetter, Cantrell, Hall, ACPD 2008

Mexico City Outflow New York City Outflow

NYC – rapid conversion of NOx into

• HNO3. Very little NOx remains one day

downwind to produce additional ozone. MC – because of high hydrocarbons, reactive nitrogen is carried out in its

• rganic forms (PANs), which release

NOx on a regional scale. This results in additional ozone production further downwind. The very high NOx and very high hydrocarbon emissions typical for a megacity like MC combine non-linearly to extend its impacts to a much larger region.

The Long Reach of a Megacity

Flocke et al. AGU’07

WRF-Chem: HNO3 Loss on Dust

24 Hodzic et al., AGU’07

UV Actinic Flux Reduction  Slower Photochemistry

25 Madronich, Shetter, Halls, Lefer, AGU’07

1E+14 2E+14 3E+14

300 320 340 360 380 400

Quanta cm-2 s-1 nm-1

Wavelength, nm

• bs

tuv-clean tuv-polluted

18 March 16:55 LT solar zenith angle = 65o

Sub-Micron Aerosol Composition

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Flights over city Flights outside city

DeCarlo et al. ACPD 2008 Source: Salcedo et al., ACP. 2006.

Total: 31µg/m3 CENICA Supersite (MCMA-2003)

Secondary Aerosol Production in Mexico City Urban Plume as Function of Photochemical Age

Secondary aerosol production in Mexico City urban plume measured from the G-1 as a function of photochemical age using – Log (NOx/NOy) as clock. Dilution is accounted for by normalizing aerosol concentration to CO above background. Total aerosol concentration increases by factor of 5-7 due to formation of secondary aerosol over the course of one day. (Kleinman et al., 2008). Concentration Normalized Concentration

Models Under-predict SOA

Volkamer, R., J.L. Jimenez, F. San Martini, K. Dzepina, Q. Zhang, D. Salcedo, L.T. Molina, D.R. Worsnop, and M.J. Molina, Geophys. Res. Lett., 33, L17811, doi:10.1029/2006GL026899, 2006

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Oxygen/Carbon Ratio of Organic Aerosols

Age = - Log(NOx/NOy)

0.0 0.2 0.4 0.6 0.8 1.0

Fraction of Organic Aerosol

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

OOA HOA

high O/C low O/C Condensation

• f gas-phase
• xygenated
• rganics

DeCarlo et al. ACPD 2008

Age = - Log (NOx/NOy)

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• single scattering albedo)

 coating of new BC

• specific light absorption

(absorption/BC)  lensing by shell to core

Specific Absorption

Age = - Log(NOx/NOy)

0.0 0.2 0.4 0.6 0.8 1.0

PSAP/CO regression slope (Mm-1/ppb)

0.01 0.02 0.03 0.04 0.05

Downwind Evolution of Aerosol Optics

Kleinman et al., in prep.

Age = - Log(NOx/NOy)

0.0 0.2 0.4 0.6 0.8 1.0

Single scatter albedo (550 nm)

0.70 0.75 0.80 0.85 0.90 0.95 1.00

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HSRL (532 nm) AATS (519 nm) Hi GEAR (550 nm)

Coordinated spirals by Be200 (HSRL), J31 (AATS), & C130 (in situ)

Aerosol Extinction Intercomparison

Hair, Hostettler, Ferrare, Redemann, Livingston, Clarke, et al., in prep.

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Biomass Burning

Fire markers detected frequently:

Aerosols Levoglucosan (from cellulose)

14C (modern carbon)

Single particle analyses Gases HCN, CH3CN (but these could also have vehicular sources) PAN/PPN ratios Many fire plumes were sampled: High emission factors for NOx, HCN, NOy More important for aerosols than gases

Yokelson et al.,ACP 2007; Moffet et al. ACPD 2007; Jimenez et al., Herndon et al., Emmons et al. in prep.

Biomass

Fresh Urban Photochemistry “clean”

• r above ML

MODIS fire counts March 2006

NOy & OH observations and model simulations

• ver the Gulf of Mexico

2 4 6 8 10 12 500 1000 1500 2000 2500 3000

DC8_INTEX-B C130_INTEX-B DC8_GEOS-Chem C130_GEOS-Chem DC8_STEM C130_STEM DC8_MOZART C130_MOZART

Altitude, km NOy, ppt

2 4 6 8 10 12 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

INT EX-B _DC8 GE OS - Chem_DC8 ST EM_DC8 M OZA RT _DC8 DC8_RA QMS DC8_BOXMODEL

Altitude, km OH, ppt

Courtesy: Singh et al.

Alkyl and Multifunctional Nitrates vs. Altitude

None of the models used to describe the DC-8

• bservations

accurately reproduce AN abundances & the AN fraction of NOy

2 4 6 8 10 12 50 100 150 200 250 300

INTEX-B R EG 2

ALT, km Alkyl nitrates, ppt

ANs RONO2

Data over Gulf of Mexico

Courtesy: Singh et al.

2 4 6 8 10 12 200 400 600 800 1000

INT EX-B _DC8 GE OS - Chem_DC8 GE OS - Chem_C130 M OZA RT _DC8 M OZA RT _C130 DC8_RA QMS C130_RAQM S

Altitude, km CH3OOH, ppt

Reg 1: Gulf of Mexico

2 4 6 8 10 12 500 1000 1500 2000 2500

INT EX-B _DC8 INT EX-B _C130 GE OS - Chem_DC8 GE OS - Chem_C130 ST EM_DC8 ST EM_C130 M OZA RT _DC8 M OZA RT _C130 DC8_RA QMS C130_RAQM S

Altitude, km CH2O, ppt

Courtesy: Singh et al.

2 4 6 8 10 12 200 400 600 800

DC8_INTEX-B C130_INTEX-B DC8_GEOS-Chem C130_GEOS-Chem DC8_STEM C130_STEM DC8_MOZART C130_M OZART

Altitude, km PAN, ppt

DC-8/C-130 over Gulf of Mexico

Courtesy: Singh et al.

2 4 6 8 10 12 200 400 600 800 1000 1200 1400

DC8_INTEX-B C130_INTEX-B DC8_GEOS-Chem C130_GEOS-Chem DC8_STEM C130_STEM DC8_MOZART C130_M OZART

Altitude, km Acetaldehyde, ppt

DC-8/C-130 over Gulf of Mexico

2 4 6 8 10 12 50 100 150 200 250 300 350

INT EX-B_DC8 INT EX-B_C130

Altitude, km Propanal, ppt

Courtesy: Singh et al.

2 4 6 8 10 12 500 1000 1500 2000

INT EX-B _DC8 INT EX-B _C130 GE OS - Chem_DC8 GE OS - Chem_C130 M OZA RT _DC8 M OZA RT _C130 DC8_RA QMS C130_RAQM S

Altitude, km Acetone, ppt

2 4 6 8 10 12 500 1000 1500 2000

INT EX-B _DC8 GE OS - Chem_DC8 M OZA RT _DC8 RA QMS_DC8

Altitude, km Acetone, ppt

Reg 1: Gulf of Mexico Reg 3- N. Pacific

Courtesy: Singh et al

2 4 6 8 10 12 100 200 300 400 500 600

INT EX-B _DC8 INT EX-B _C130 M OZA RT _DC8 M OZA RT _C130

Altitude, km Ethanol, ppt

2 4 6 8 10 12 1000 2000 3000 4000 5000

INT EX-B _DC8 INT EX-B _C130 GE OS - Chem_DC8 GE OS - Chem_C130 M OZA RT _DC8 M OZA RT _C130 DC8_RA QMS C130_RAQM S

Altitude, km Methanol, ppt

Methanol & Ethanol

Reg 1: Gulf of Mexico

Courtesy: Singh et al

A MC B C D E F MC A MC B C D E F MC

Observation of Ozone and Aerosols over Gulf of Mexico

Satellite Validation

The MILAGRO aircraft provided measurements to validate satellite-based retrievals of atmospheric optics and composition, so that these can be used over the entire globe.

Aerosol Optical Depth Comparisons

Gulf of Mexico, INTEX-B/MILAGRO, 10 Mar 2006. 2 Satellites: OMI on Aura, MODIS on Aqua. Airborne Sun-photometer (AATS-14).

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Courtesy P. Russell and the J-31 Team (NASA)

• Ozone production continues in the outflow for at least several days, due to

the formation of peroxyacetyl nitrates (PANs) which effectively increase the NOx lifetime.

• Aldehydes are major components of the outflow reactivity.

They are produced by atmospheric VOC oxidation, and some are also emitted directly. Although important, they are not routinely measured.

• The production of O3 and aerosol particles continues for hundreds of

kilometers downwind of Mexico City. Partly because Mexico City has high NOx levels and haze-limited photochemistry, a substantial fraction of urban emissions exiting the city is still reactive, and thus contributes more to O3 formation outside the city and in larger geographic areas.

• Organic aerosols grow in the city and in the downwind plume. Current

models can explain only a small fraction of this growth. The MILAGRO data are providing a test-bed for exploring different hypotheses of organic aerosol evolution.

• Satellite retrievals of aerosols are being improved by comparisons with

measurements of radiation and aerosol properties at the surface and from aircraft.

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SOME MILAGRO RESULTS

SOME MILAGRO RESULTS

• Regional impacts of MCMA are easily discernible, esp. to the SE, south and

west where other sources are smaller and MCMA provides the dominant

• influence. Contribution of MCMA pollutants to the NE is not so easily

apportioned because of the influence from US, regional BB, and N Mexico. The MCMA plume was detected at distances up to 1000 km downwind.

• Emission inventories used in models are being re-evaluated with
• bservations of concentrations of many species, and fluxes for a few.
• Urban photochemical smog formation is VOC-limited, and despite the high
• VOCs. Reductions of NOx emissions may however reduce regional oxidant

formation.

• Aerosols within the MCMA have a large organic component. Both fossil fuel

use (mostly urban emissions) and biomass burning (mostly agricultural and forest fires outside the city) contribute to the amount of aerosol.

• Biomass burning contributes to urban and regional pollution, more so for

aerosols than gases. Agricultural, forest, and trash fires are common, and their plumes carry distinct chemical signatures.

• Aerosol optical properties are changing rapidly during plume export. Both

the single scattering albedo and the black carbon specific absorption increase with time. Models of aerosol growth, microphysics, and optics are being evaluated with MILAGRO data.

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SUMMARY

• Extremely rich data set
• Full use of data will take several years of collaborative work
• Many important features already identified
• Urban photochemistry fast but could be faster
• VOC-limited, high NOx suppresses OH/O3
• Photon-limited by aerosols
• Emissions too strong for local oxidizing capacity
• Strong regional photochemistry of exported pollutants
• Continuing production of O3 and aerosols
• Aerosol optical properties evolve over several days
• Dilution may help with local health impacts, but not with climate

impacts

• Large concentrations of OVOC present throughout the

troposphere.

• Evaluation of source-sink relations currently underway.
• Interactions with biomass burning, dust

Some Concluding Observations from INTEX-B

• INTEX-B/Milagro:
• Provided a comprehensive and unified data set to determine the

composition

• f

Mexico City pollution plumes, their persistence, & transformation

• Validated satellite observations of tropospheric composition
• Related atmospheric composition to emissions
• Tested chemical transport models & their forecasts
• Paper are being published in ACP
• Large concentrations of OVOC present throughout the
• troposphere. Source-sink relations uncertain due to:
• Measurement errors
• Model uncertainties
• Poor bottoms-up source estimates
• Significant trends in composition

MILAGRO Sponsors

• Comisión Ambiental Metropolitana (Mexico)
• Instituto Nacional de Ecología -SEMARNAT (Mexico)
• CONACyT (Mexico)
• PEMEX (Mexico)
• National Science Foundation Atmospheric Chemistry Program

(USA)

• Department of Energy Atmospheric Science Program (USA)
• NASA Tropospheric Program (USA)
• European agencies
• Others