henk eskes, omi meeting 20-22 june 2006 omi nitrogen dioxide: the knmi near-real time product henk...

Henk Eskes, OMI meeting 20-22 June 2006

OMI Nitrogen Dioxide: OMI Nitrogen Dioxide: The KNMI Near-Real Time ProductThe KNMI Near-Real Time Product

Henk Eskes, Pepijn Veefkind, Folkert Boersma, Ronald van der A,Ellen Brinksma (KNMI)

Eric Bucsela, Ed Celarier, Jim Gleason, Mark Wenig (NASA)


NO2 retrieval

Combinedretrieval-modelling-assimilation-approach

• Detailed error estimates• Averaging kernels


OMI near-real time processing

DOMINO project:Dutch funding: NIVR, GO-2 programFolkert Boersma, Jan 2005 - Nov 2005

DOMINO-2 project:July 2006 - June 2007Ruud Dirksen


• To provide users with near-real time air pollution monitoring

• Users include:- environmental agencies- air quality forecasters- GEMS (EU GMES) lead by ECMWF

NRT comparison OMI with regional AQ modelsover Europe

- PROMOTE (ESA GMES)- …

Purpose (1)


To generate a long-term consistent dataset from:- GOME (1996 - 2003)- SCIAMACHY (2003 - )- OMI (2004 - )- GOME-2 (2006 - )

KNMI retrieval algorithm for tropospheric NO2• Data publicly available via www.temis.nl • Described in Boersma et al. (JGR, D04311,2004)

Purpose (2)


Ingredient 1: Daily chemical forecast with OMI NO2 assimilation


Ingredient 2: Near-real time OMI tropospheric NO2 retrieval

NASA/KNMI DOAS algorithm


1. Find window with smallest variation in initial columns

2. Compute mean column vs. across track viewing angle

3. FFT analysis to smooth

Stripe correction


http://www.temis.nl/airpollution/no2.html

Images available within ~2hrs - data acquisition- downlink- processing - KNMI/NASA DOAS algorithm

~2 hrs

- NRT processing time:< 2 minutes

Near-real time processing


Near-real time processing started 7 October 2005 has been quite reliable / robust (2 major events: upgrade ECMWF and TM input file error)

Off-line archive: Sep 2004 - Aug 2005 including Dandelions period

Near-real time archive: October 2005 - present

Near-real time processor: first results


KNMI OMI near-real time NO2, 13-16 Oct 2005

SundaySaturday


Chimere model @ OMI overpass time, 13-16 Oct 2005


SCIAMACHY, October 2004


OMI, October 2004


SCIAMACHY - OMI, October 2004


Algorithm• Clouds (impact of O2-O2, eg use also Raman), Albedo, Stripes, ..

Comparisons• SCIAMACHY• Regional models like Chimère• Operational vs NRT

Validation• Campaigns like Dandelions, INTEX• MaxDOAS, SAOZ, ..• Surface obs

Promote use of OMI NO2 products

PlansPlans


GOME/SCIA experience• retrieval improvements should focus on cloud/aerosol

treatment, surface albedo, stratospheric background, profile shape

OMI• Based on KNMI/NASA operational slant column retrieval

and KNMI retrieval/modelling/assimilation approach for AMF• Near-real time processing ingredients:

1. daily TM4/5 forecast/assimilation runs2. retrieval on orbit by orbit basis

• Operational since 7 October 2005

ConclusionsConclusions


NO2 retrieval: error contributions

Typical 30-50% error for individual pixelsBoersma et al. JGR 2004


Eleven years of NO2 data

KNMI - IASB:GOME, 1996 - 2003SCIAMACHY, 2003 - 2006

KNMI - NASA:OMI, 2004 - present

Images and detailed data products, including averaging kernels and error estimates,available on the TEMIS and PROMOTE web sites

www.temis.nlwww.gse-promote.org


Trend over China

GOME, 1997 SCIA, 2004


GOME NO2 intercomparison

IPCC study:Comparison NO2 retrievals GOME• Univ. Bremen (A. Richter)• Harvard, Dalhousie (R. Martin)• IASB / KNMI



The three algorithms follow the same approach:1. DOAS slant column fit2. Estimate stratospheric part of the slant column3. Calculate tropospheric AMF based on model-

generated profile shapes

But have very different building blocks



IUP Bremen Dalhousie KNMI/BIRA

Ns425 – 455 nm 425-450 nm 426.3 – 451.3 nm

Ns,stRef. sector scaled to SLIMCAT strat.

Ref. Sector Data-assimilation in TM4

Cloud fraction (albedo)

FRESCO 0.2 cloud fraction; only cloud selection, no further correction

GOMECAT (Kuruso) FRESCO (0.8)

Cloud pressure Not used GOMECAT FRESCO

Albedo GOME (Koelemeijer) GOME(Koelemeijer) TOMS/GOME (1x1)

Profile shape MOZART-2 run for 1997, monthly averages on 2.8 x 2.8 °

GEOS-CHEM TM4 (3x2)

Temperature correction

No ? Yes, ECMWF T-profiles


SCIAMACHY vs. Chimère: yearly mean 2003

Nadège Blond

henk eskes, omi meeting 20-22 june 2006 omi nitrogen dioxide: the knmi near-real time product henk...

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