March 4, 2008AeroCenter Update 2008 How do aerosols affect air quality, the human environment, and...

March 4,

2008AeroCenter Update

2008

How do aerosols affect air quality, the human

environment, and natural ecosystems?

For AeroCenter Update, March 8, 2008 (Year of the Rat)

Mian Chin

Many othersand

March 4,


2008

Aerosol affects air quality – Emission, transport, and

amount of surface particulate matter

March 4, 2008

AeroCenter Update 2008

PM air quality

• Aerosol particles, also called particulate matter (PM) in air quality terms, exert health and environmental problems when in high concentrations

EPA Standards for PM air quality:

Air Quality Color ScalePM2.5 PM10

(µg m-3) (µg m-3)

Good Green 0 – 15 0 – 54

Moderate Yellow 16 – 40 55 – 154

Unhealthy for sensitive groups

Orange 41 – 65 155 – 254

Unhealthy Red 66 – 150 255 – 354

Very unhealthy Purple 151 – 250 355 – 424

Hazardous Maroon 251 – 500 425 – 604

March 4, 2008


Sources of PM:

• Local/Regional:– Power plants, automobiles, fires, dust, and other natural

sources (trees, volcanoes)• Transboundary transport from outside:

– Pollutants, smoke, and dust generated from other regions that can be transported into region of interest

• The extent of impact of long-range transport and regional emissions on air quality depends on the amount emitted locally and the vertical locations of PM from outside regions

March 4, 2008


MODIS AOD

Red: fine mode Green: coarse mode

Sources and transport from observations and models

From: Yoram Kaufman

GEOS-4 model AOD

Green: carbonaceous or sulfate Orange: dust Other color: mixture

From: Peter Colarco

Asian dust over central Pacific during INTEX-B (Spring 2006)

From: Ken Pickering & Tom Kucsera

3-day OMI AI ExposureLangley aircraft lidar Ed Bowell

March 4,


2008

What can satellite data tell us about the long range transport of pollution beyond pretty pictures?

A Satellite-based assessment of trans-Pacific transport of pollution aerosol

Hongbin Yu, Lorraine Remer, Mian Chin, Huisheng Bian, Richard Kleidman, Thomas Diehl, JGR in press, 2008 (Kaufman special issue)

March 4, 2008


Yoram Kaufman’s formula:

Anthropogenic (pollution + smoke) AOD over oceans derived from MODIS

Anthropogenic AOD MODIS

)(

)()(

da

mdmda ff

ffff

– Whereτ, τa and τm are total, anthropogenic, and maritime aerosol optical thickness

– fτ, fd, fm, fa are fractions of fine mode, dust, maritime, and anthropogenic aerosol optical thicknesses

– τa is derived using a modified/ improved Kaufman method

– Using vertical information from GLAS and CALIPSO, RH data from AIRS, and mass extinction efficiency from field measurements to convert τa to mass flux

MODIS seeing pollution from China spilled over NW Pacific on Jan. 1, 2007.

From: Hongbin Yu (Yu et al., 2008)

March 4, 2008


Measurement-based estimate of transpacific transport of anthropogenic aerosols

• Using aerosol products from multiple satellite sensors (MODIS, GLAS, CALIPSO, AIRS) and from field measurements

• ~ 18 Tg/year pollution aerosol is exported from East Asia (and its upwind regions) to NW Pacific

• ~ 4.5 Tg/year (25%) reaches the west coast of North America

• This imported amount is about 15% of the total anthropogenic emissions in U.S. and Canada

• GOCART and GMI model simulations show similar magnitudes with satellite-based estimate, which is the total column amount

Export

Import

From: Hongbin Yu (Yu et al., 2008)

March 4,


2008

The above study is an estimate of total column flux – how does this transport affect the surface air quality?

Intercontinental transport of pollution and dust aerosols: Implications for regional air quality(A modeling study)

Mian Chin, Thomas Diehl, Paul Ginoux, William Malm, ACP 2007

March 4, 2008


The impact is critically dependent on vertical extent of transported aerosol plume

Leaving Asia Entering N. Am.

Asian pollution: • Max in at surface leaving Asia• Max above surface (1.5 – 4 km)

entering North America • Requiring downward mixing to send

stuff to North American surface

European pollution: • Contributing 10 – 50% in the “Asian

outflow”!

GOCART model study

Ratio of imported to locally emitted athropogenic fine mode PM at surface: - From 14% in NW to 3% in SE U.S.

March 4,


2008

Other studies showing the importance of aerosol vertical profiles to map the column amount to surface PM:

• Using GEOS-CHEM model to map MISR data to surface PM2.5 – Y. Liu, Kourtakis, R. Kahn, et al, JAWMA 2007

• 3-D Air Quality System project – R. M. Hoff, K. McCann, H. Zhang, A. Prados, and J. Engel-Cox

• Using Giovanni tool to map MODIS AOD to surface PM2.5 – A. Prados and Greg Leptoukh

March 4, 2008


MIS

R-C

onst

rain

ed M

odel Eastern US

Western US

EPA SurfaceSurface Measurements

PM2.5 SO4

MISR & GEOS-Chem – Mapping near-surface pollution

(Liu, Krukakis, Kahn et al., 2007)

• MISR provides total-column AOT over land to constrain model• MISR also gives particle shape to separate dust & spherical particles --> much better result• GEOS-CHEM provides aerosol vertical distribution + detailed spherical-particle chemical

speciation

March 4, 2008


3-D Air Quality System (R. Hoff et al.)

• Integrate NASA satellite sensor and lidar data into EPA’s air quality data systems

• Provide greater accessibility and usability of satellite and lidar data to users of these systems

• Enable monitoring in horizontal and vertical dimensions for forecasting and retrospective analysis

MODIS 10x10 granuleAOD product

Remapped MODIS 12x12 CMAQGridded AOD product

Calipso and UMBC Lidar data mapped to EPA PM sites

March 4, 2008


Assessing U.S Air Quality with Giovanni

(Ana Prados and Greg Leptoukh)

• Data sets: MODIS Terra and Aqua AOD, EPA PM2.5, CALIOP, OMI NO2 and Aerosol Index• Services: include AOD/PM2.5 correlation maps and scatter plots, and image loops for

examining long range transport of pollutants

Lev

el-3

MO

DIS

AOD

EPA

PM2.

5 (u

g/m

3)

May 22nd, 2007: Smoke over north Carolina. High AOD and low PM2.5 (r=0.54). There is also haze in the southeast

Improved correlation over this region when excluding smoke areas (r=0.80)

Giovanni data sets and tools help provide a more complete understanding of the origin, evolution, and vertical distribution of aerosol pollution over the continental U.S.

March 4, 2008


Remarks on aerosol impact on air quality

• Key quantities: Vertical distribution; composition; and particle size

• Current satellite data have limited information on these quantities

• There are innovative methods to estimate the transport and “retrieve” surface PM from current satellite observations but with large uncertainties

• Future satellite mission should focus on improving capabilities on observing the key quantities with adequate spatial coverage and accuracy

March 4,


2008

Aerosol affects human environment – Global dimming/brightening

March 4, 2008


Multi-decadal change of solar radiation reaching the surface

• Solar radiation reaching the surface (Ssfc) is the primary energy source for life, and any change of this radiation could substantially affect the climate, hydrological cycle, and ecosystems– Surface water evaporation– Soil moisture– Crop yield– CO2 uptake

March 4, 2008


Multi-decadal change of solar radiation reaching the surface – global

dimming/brightening

From: David Streets (Streets et al., 2004, 2006)

Stations over Japan and Russia

Anthropogenic SO2 emissions

TotalOther regions

East Asia

Former USSREastern EuropeOECD Europe

U.S.A.

52 stations avg over China

SW

ir

rad

ian

ce

• Long-term observations of Ssfc have shown a decline in solar radiation up to 1990 at several different regions of the world (dimming)

• Recent measurements have indicated an increase of Ssfc since about 1990 over many regions of the world (brightening)

• Anthropogenic emission change mirrors the change of Ssfc, suggesting possible roles of aerosols

• Many other factors can also contribute to the Ssfc change, such as clouds

• Global or regional or local?

March 4, 2008


Long-term variations of AOD (1979 – 2006)(Preliminary GOCART results)

• Using time-varying anthropogenic emission 1979 - 2006 from David Streets

• Compiling volcanic, biomass burning, aircraft/ship emissions (T. Diehl)

• Calculating dust and sea-salt emissions as a function of wind speed and surface conditions

Global ocean avg AOD, 60S – 60N

Global land avg AOD, 60S – 60N

Figure from: Thomas Diehl

March 4, 2008


What is the relationship between aerosol emission, AOD, and Ssfc? (Preliminary GOCART results

– annual avg)

Sulfur Carbonaceous Dust Sea-salt

Emiss

ion

AOD

550

nmEm

issio

n v

s AO

D

1991

19921993

1982

1997

1998

March 4, 2008


Remarks on aerosol impact on surface radiation

• Key quantities: direct and diffuse SW solar radiation at the surface, under both cloudy and clear skies, and aerosol amount and optical properties

• Current satellite retrieval of surface radiation (e.g. from ISCCP or CERES) suffers from difficulties in specify aerosol amount and optical properties

• Current surface radiation networks are limited for adequate global assessment

• Long-term monitoring of surface radiation and aerosols from ground-based network is needed

• Better retrieval of surface radiation from space requires much better knowledge of aerosol properties

March 4,


2008

Aerosol affects natural ecosystem – Dust and ocean productivity

March 4, 2008


Connection between dust and ocean biology

• Iron supply is a limiting factor on phytoplankton growth over vast areas of the ocean

• Deposition of dust transported from deserts is believed to be the main source of iron to the open ocean

• However, dust-marine productivity connection depends on the amount of soluble iron, Fe(II)

Global iron and dust connections

From: Jickells et al., Science 2005

March 4, 2008


• Phytoplankton activity is very sensitive to changes in nutrient availability (particularly in the Southern Ocean)

Soiree Experiment, Edward et al, Nature 2000)

Artificially seeded Fe in the Southern Ocean

Visible chlorophyll enhancement afterwards

Dust as a Tracer of Climate Change in Antarctica and as modulator of Phytoplankton

Activity

March 4, 2008


Global distributions of Chl. and aerosol

• Satellite retrieves both ocean Chl. (e.g. MODIS and SeaWiFS) and dust aerosols (e.g. MODIS coarse mode, MISR non-spherical), which can be potentially used to link dust to ocean productivity

• But absorbing aerosols (dust, smoke) remain problematic in ocean color data processing

January 2001

Chlorophyll Concentration

From: W.E. Esaias

Aerosol Optical Thickness

April 2001From: C. McClain

March 4, 2008


A combination of MODIS and OMI observations shows

dust traveling a long way in the South AtlanticMODIS Aerosol Optical Depth OMI Aerosol Index

Gassó & Stein, GRL 2007

• Observation of dust in the SO is very difficult because:– Very cloudy --- > very few clear sky retrievals ----- > sampling problem– Dust activity is episodic and in pulses.– Only a combination of satellite retrievals and surface (ship) can help to

understand dust transport and detection in the SO as this example shows.

March 4, 2008


Dust deposition over Atlantic Ocean derived from Terra + Aqua MODIS

1. Obtain dust AOD τd:

2. Estimate vertical profiles using “virtual lidar” – correlations with the NCEP winds

3. Convert dust AOD to mass4. Using wind speed and

Terra/Aqua dust mass differences to estimate the dust mass transport

5. Derive dust deposition

Kaufman et al. 2005 estimated:

• 240 ± 80 Tg of dust are transported annually from Africa to Atlantic

• 50 Tg fertilize the Amazon Basin• 50 Tg reach the Caribbean• 20 Tg return to Africa and Europe

Yoram Kaufman’s method:

Estimated dust flux, Kaufman et al., JGR 2005

)(

)()(

da

mmamd ff

ffff

March 4, 2008


Remarks on aerosol impact on ocean biology

• Key quantities: dust aerosol amount and deposition, soluble iron, ocean phytoplankton/chlorolphyll

• Current satellite retrievals of ocean color requires accurately accounting for aerosol “interference”

• It is very difficult to observed dust when clouds present• It is even more difficult to know if iron from dust is active• Future satellite observation should have a better capability

to detect dust even in cloudy conditions with adequate spatial coverage

• Although dust deposition cannot be directly observed by satellites, it can be derived with higher temporal satellite coverage (several times/day) to see aerosol moving and change

March 4, 2008AeroCenter Update 2008 How do aerosols affect air quality, the human environment, and...

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