07.04.2009

Lok Lamsal, Randall Martin, Aaron van Donkelaar Folkert Boersma, Ruud Dirksen (KNMI)

Edward Celarier, Eric Bucsela, James Gleason (NASA)

E.S. Edgerton, B. Hertsell (ARA Inc.)Y. Wang, C. Luo (Georgia Institute of

Technology)

Seasonal Variation of Nitrogen Oxides at Northern

Midlatitudes as Inferred from Ground- and

Satellite-based Observations

Lok Lamsal, Randall Martin,

Aaron van Donkelaar

Folkert Boersma, Ruud Dirksen (KNMI)

Edward Celarier, Eric Bucsela, James

Gleason (NASA, GSFC)

28.07.2009

MOCA-09, Montreal, July 19-29

Substantial Seasonal Difference in Tropospheric NO2 Columns: Example from

GOME

van Noije, ACP, 2006

Retrievals from University of Bremen, Dalhousie/SAO, BIRA/KNMI

Difference in winter up to a factor of 2

Monthly tropospheric NO2 columns over Eastern U.S. from three independent retrievals

(71-90W, 35-43N)

Uni Bremen

BIRA/KNMI

Dalhousie/SAO

Large Seasonal Difference in Tropospheric NO2 Columns Among OMI Retrievals

How does the actual seasonal variation look like? Which one is closer to reality?

What causes the observed difference?

What drives the seasonal variation?

Research Questions:

Monthly tropospheric NO2 columns over the United States from OMI

Standard Product (SP)

DOMINO Product (DP)

DP_GCDOMINO product with stripes correction and GEOS-Chem NO2 profilesModified DP (DP_GC)

Comparison of OMI NO2 with Surface Measurements

OFGG

GO Ω

1)Ω(λλΩ

λSS

O

O

Ω

Ωλ ,

(B) Derive surface-level NO2 from OMI (Lamsal et al., 2008, JGR)

(A) In-situ surface NO2 measurements from the SEARCH and EPA/AQS networks (Rural sites only)

×

SEARCH (3)

EPA/AQS (8)

Comparison of OMI-derived Emission with Bottom-up Inventory

(B) Derive top-down emissions from OMI (Martin et al., 2003, JGR)

mod sat bg

sat modi,j i,j i,j1 1 mod bgi,j i,j

modi,j i,j

m,n i+m,j+nm=-1n=-1

= × ×E Ω Ω

E EΩ Ωk E

(A) Updated bottom-up emission inventories

VISTAS 2002 and CAC 2005 (North America)

EMEP 2005 (Europe)

Street 2006 (East Asia)

Summary of Comparison - Validation of OMI Tropospheric NO2

SEARCH domain North America

SEARCH, Southeastern U.S. AQS/EPA, U.S.

What Causes the Observed Difference?

Algorithm

component

Standard product (SP) DOMINO (DP) DP_GC

Slant column DOAS fit (405-465nm) Same as SP

Stripe correction? Yes No Yes

Strat-trop separation Analysis of

observation

TM4

assimilation

Trop NO2 profile GEOS-Chem annual Daily TM4 Daily

GEOS-Chem

Scattering weights TOMRAD DAK

Surface reflectivity GOME climatology GOME+TOMS

Surface pressure Climatological ECMWF

Cloud

pressure/fraction

O2-O2 cloud algorithm Same as SP

AMF

Difference Between DP and SP: Contribution of Stratosphere-troposphere Separation and AMF

Strat-trop separation Air mass factor Combined

What Drives the Seasonal Variation in Tropospheric NO2?

τGC

τOMI

τGC

Seasonal variation in (a) NOx

emissions

(b) NOx lifetime

Daily Average

OMI time

OMI time

Gas phase (NO2 + OH)

Aerosol uptake of NO2, NO3, and N2O5

Indirect validation of tropospheric nitrogen dioxide retrieved from the OMI satellite instrument: Insight into the seasonal variation of nitrogen oxides at northern midlatitudes, 2009, L. N. Lamsal, R. V. Martin, A. van Donkelaar, E. A. Celarier, F. K. Boersma, R. Dirksen, C. Luo, and Y. Wang, J. Geophys. Res., Submitted