Future directions in tropospheric chemistry - PowerPoint Presentation

Slide1

Future directions in tropospheric chemistry – what else besides climate change

Daniel J. Jacob

Group photo (2013)

Range of tropospheric chemistry problems

LOCAL

< 100 km

REGIONAL

100-1000 km

GLOBAL

> 1000 km

Urban smog

Plume dispersion

Disasters

Visibility

Regional smog

Acid rain

Ozone

layer

Climate

Biogeochemical cycles

CLIMATE!

Range of tropospheric chemistry problems

LOCAL

< 100 km

REGIONAL

100-1000 km

GLOBAL

> 1000 km

Urban smog

Plume dispersion

Disasters

Visibility

Regional smog

Acid rain

Ozone

layer

Biogeochemical cycles

Jennifer’s foray into ozone smog

Nitrogen oxides in the troposphere:

global and regional budgets (Logan, 1983) –

508 citations

The sensitivity of ozone to nitrogen oxides and hydrocarbons in regional ozone episodes (

Sillman

, Logan,

Wofsy

, 1990)

-

283 citations

Ozone in rural areas of the United States (Logan, 1989) -

159 citations

Factors regulating ozone over the United States and its export to the global atmosphere (Jacob, Logan, et al. 1993) –

150 citations

This report paved the way

f

or

NO

x

controls!

(1991)

Trend in 95th percentile daytime ozone, 1990-2010

Spring

Summer

Cooper et al. [2012]

Decrease in eastern US driven by

NO

x

emission controls;

Increase or flat in Intermountain West

4th-highest annual maximum for daily 8-h average ozone,2008-2010

Intermountain West: The next ozone frontier!

Current standard: 75 ppb

Proposed standard: 60-70 ppb

Surface ozone at Gothic, Colorado

Most ozone originates from outside N America

Peak events of stratospheric influence cannot be reproduced by model

Zhang et al., in prep.

Numerical decay of a

f

ree tropospheric plume

In GEOS-

ChemEulerian

models have difficulty preserving gradients (layers) in divergent free tropospheric flow, in a way that cannot be readily fixed by increasing grid resolution or the accuracy of numerical scheme

Rastigeyev et al. [2010]

Ammonia emission and air pollution

Observed NH

4

+

wet deposition fluxes can constrain NH

3

emission estimates

NADP data (circles) and GEOS-

Chem

model after adjoint inversion

April:

fertilizer

July:

livestock

kgN

ha

-1

month-1

Contribution of food export

to annual PM2.5

(ammonium nitrate)GEOS-Chem sensitivity simulationFabien Paulot (in prep.)

Critical load exceedances for N deposition at US national parks

Ellis et al. [2013]

More deposition is expected to originate from ammonia in future

Critical loads are 3-5 kg N ha

-1

a

-1

depending on ecosystem

2006

2050 NOx

NH3

Present and future (RCP)

US emissionsFuture exceedances driven byammonia emissionsEllis et al. [2013]

2006

2050RCP2.6

Next frontier for air pollution: Nigeria

OMI formaldehyde

2005-2009

MISR

SCIA

a

erosol (AOD) NO

2

HCHO

glyoxal

methanePopulation: 270 million (+2.6% a-1)

GDP: $273 billion (+7% a-1) – oil!Most natural gas is flared>80% of domestic energy from biofuel, waste

LagosPortHarcourt

An unusual mix of very high VOCs, low NOx –What will happen as infrastructure develops?Eloise Marais [Harvard]

gasflaring!

Biogeochemical cycle of mercury

Hg(0)

Hg(II)

particulate

Hg

burial

SEDIMENTS

uplift

volcanoes

erosion

oxidation

Hg(0)

Hg(II)

reduction

biological

uptake

ANTHROPOGENIC

PERTURBATION:

fuel combustion

mining

ATMOSPHERE

OCEAN/SOIL

VOLATILE

WATER-SOLUBLE

(months)

l

ifetime

~6 months

History of global anthropogenic Hg emissions

Large past (legacy) contribution from N. American and European emissions;

Asian dominance is a recent phenomenon

Streets et al. , 2011

Global source contributions to Hg in present-day surface ocean

Human activity has increased 7x the Hg content of the surface ocean

Half of this human influence is from pre-1950 emissions

N America, Europe and Asia share similar responsibilities for anthropogenic Hg in present-day surface ocean

Amos et al., in press

Europe

Asia

N America

S America

former USSR

ROWpre-1850

natural emissionsfrom biogeochemical box model constrained with GEOS-Chem

fluxes

Disposal of Hg in commercial products:a missing component of the Hg biogeochemical cycle?

Global production of commercial Hg peaked in 1970

Hannah Horowitz (Harvard)

Global tropospheric Bry budget in GEOS-Chem

(Gg Br a

-1)

SURFACE

CHBr

3

407

CH

2

Br2

57

CH3BrMarine biosphere

Sea-salt debromination(50% of 1-10 µm particles)

STRATOSPHERETROPOSPHERE7-9

pptLiang et al. [2010] stratospheric Bry

model (upper boundary conditions)

56

36

Volcanoes

(5-15)

Deposition

l

ifetime 7 days

1420

Sea salt is the dominant global source but is released in marine boundary layer

where lifetime against deposition is short; CHBr

3 is major source in the free troposphereParrella

et al. [2012]Bry3.2

pptBrO0.32 ppt

Bromine chemistry improves simulation of 19th century surface ozone

Standard models without bromine are too high, peak in winter-spring; bromine chemistry corrects these biases

Implies that anthropogenic perturbation to global tropospheric ozone is larger than currently assumed

Parrella

et al. [2012]

Elusive understanding of what controls tropospheric OH

GEOS-

Chem

with climatological lightning

GEOS-

Chem

with

interannual

lightning (LIS)

Lightning seems to be a major driver of OH variability (Murray, Logan, Jacob, 2013)

LIS+OTD (satellite)

l

ightning, 1995-2005

Tropical lightning

interannual variability

TEMPO geostationary UV/Vis satellite instrument

selected in November 2012 for 2018 launch

PI: Kelly Chance, Harvard-Smithsonian

Monitoring of

tropospheric

ozone (2 levels), aerosols, NO

2

, SO

2

, formaldehyde, glyoxal with 1-hour temporal resolution, 2-km spatial

resoutionTo be part of a geostationary constellation with other sensors observing Europe and East Asia

TEMPO Sentinel-4 GEMS

Next frontier in satellite observations

of atmospheric composition!