KNMI, P. Levelt II (pdf) - SRON

OMI on board 

EOS-Aura 

Dr. P.F. Levelt 

OMI Principle Investigator, KNMI

OMI on EOS Aura 

• New generation spectrometer for Earth observation 

• Dutch-Finnish contribution to EOS-Aura (NIVR/FMI) 

• KNMI is the PI institute for OMI 

Visit TU-Eindhoven, 11 February 2003 Slide 2 

P.F. Levelt, KNMI (Royal Netherlands Meteorological Institute)

KNMI Organisation 

Director KNMI 

Prof. Dr. J. de Jong 

Weather 

forecast 

Data & 

models 

Climate 

Research 

Infrastructure 



KNMI Organisation 

Climate Research 

Prof. Dr. G. Komen 

Atmosph. 

Research 

Dr. R. Boers 

Atmosph. 

Comp. 

Prof. Dr. 

H. Kelder 

Klimate 

Scen. 

Oceano- 

graphy 

Varia- 

bility 

Seis- 

mology 

Satellites 

Dr. R. van Oss 

Models 

Dr. P. van Velthoven 

OMI 

Dr. P.F. Levelt 



EOS Aura Project 

Program Scientist 

P. Decola 

Project Scientists 

M. Schoeberl 

A. Douglass 

E. Hilsenrath 

Instrument PI’s 

Project Managers 

R. Pickering 

J. Loiacono 

K. McIntyre 

HIRDLS 

UCB-Oxford 

J. Gille, J. Barnett 

MLS 

JPL 

J. Waters 

OMI 

KNMI/NIVR 

P. Levelt 

TES 

JPL 

R. Beer 



International OMI Science Team 

• PI: P.F. Levelt 

• dep.PI: G.H.J. van den Oord 

• co-PI’s: E. Hilsenrath and G.W. Leppelmeier 

• US ST Leader: PK Bhartia 

• OSAB: PI + 2 co-PI’s 

• OSCT: OSAB + Workinggroup Leaders 

• OMI Working groups: 

• Algorithm, Validation, Calibration, Data Systems, Operations 

• Science 

• Key members: I. Aben (SRON), D. Hauglustaine (CEA-CNRS), 

I. Isaksen (U. Oslo), H. Kelder (KNMI), 

G. de Leeuw (TNO-FEL), U. Platt (U. Heidelberg), 

P. Simon (BIRA), P. Stammes (KNMI) 



Heritage 

GOME 

Launched April 1995 (ESA’s ERS-2) 

SCIAMACHY 

Launched February 2002 (ESA’s ENVISAT) 

TOMS 

Nimbus 7 (‘78-’93) Meteor-3 3 (‘91-’94) 

ADEOS (‘96-’97) Earth Probe (‘96- present) 

GOMOS 

Launched February 2002 (ESA’s ENVISAT) 



EOS-Aura Platform 

• Orbit: Polar: 705 km, sun-synchronous, 98 o inclination, 

ascending 1:45 PM +/- 15 min. equator crossing time. 

• Launch date: January 2004, Delta 7920. 

• Aura will follow EOS-Aqua in the same orbit by 15 minutes. 

• Six Year Life 

MLS 

HIRDLS 

OMI 

TES 



Aura Science Questions 

Is the ozone layer recovering ? 

Is air quality changing ? 

How is Earth’s climate changing ? 



Aura Data Products 



Ozone Monitoring Instrument OMI 

• Nadir viewing 

spectrometer 

• Wavelength Range: 

270 - 500 nm 

• Spectral Resolution: 

~0.5 nm 

• Swath width: 

2600 km 

• Spatial Resolution: 

13 x 24 km 2 



OMI Instrument: 

Flight Model 



OMI Measurement Principle 



OMI: small pixels and a daily global coverage 

OMI will achieve a global 

coverage within one day 

AVHRR image of Europe, re-scaled to 

ground pixels of 13 · 40 km 2 , to give an 

impression of OMI’s spatial resolution 



A cloud free reflectivity spectrum observed with GOME on 25 

July 1995 above The Netherlands (Stammes and Piters, 1996) 



• Ozone 

− total column 

− Profile 

− Tropospheric 

• NO 2 

• Aerosols 

• Clouds 

− coverage 

− top pressure 

• SO 2 

• BrO 

• HCHO 

• OClO 

• Surface UV Irradiance 

OMI Data Products 

Source: http://toms.gsfc 

gsfc.nasa.gov/multi/ 

/multi/multim.html 



Aura Spacecraft with 

OMI, HIRDLS, 

and MLS 



OMI Science Questions 

• Is the ozone layer recovering as expected ? 

• What are the sources of aerosols and trace gases that affect 

global air quality and how are they transported? 

• What are the roles of tropospheric ozone 

and aerosols in climate change ? 

• What are the causes of surface UV-B B change? 



Is the ozone layer recovering as expected ? 

The ozone layer and its 

predicted recovery 

Monitoring of global ozone 

distributions from space by 

measuring O 3 

column and O 3 

profile 

Near real time processing - 

illustrated by assimilated GOME 

NRT observations of the split of 

the Antarctic ozone hole in 2002 

Courtesy of H. Eskes (KNMI) 



Global average ozone measured by TOMS compared with Model 

310 

eruption of Mt. Pinatubo 

65°N - 65°S 

Ozone (Dobson Units) 

300 

290 

280 

Nimbus 7 TOMS 

Meteor TOMS 

Earth Probe TOMS 

recovery predicted by model 

version 8 TOMS data 

1980 1990 2000 2010 2020 

Year 



OMI DOAS 

GOME 5-Nov-1999, 

– TOMS 

21:30, nadir 

V8 

pixels 

PRELIMINARY RESULTS 

400 

OZONE COLUMN DENSITY [DU] 

300 

200 

OMI DOAS 

TOMS V8 

100 

-90 -60 -30 0 30 60 90 

LATITUDE [degrees] 



What are the sources of aerosols and trace gases that 

affect global air quality and how are they transported? 

Biomass burning 

Urban pollution 

Global NO 2 based on GOME measurements 

(average over March 1997) [Unit: 10 15 mol/cm 2 ] 

Courtesy of H. Eskes, KNMI 

Tropospheric Pollution 

è chemical composition troposphere 

è transport of pollution 

OMI's column and profile O 3 

OMI’s column NO 2 

(in combination with limb instruments 

on EOS-Aura) 

è tropospheric O 3 

and 

tropospheric NO 2 

Aerosols, SO 2 

, HCHO 



Preliminary total columns of 

NO 2 over Europe 

Derived from SCIAMACHY 

Nadir measurements 

Compared to GOME data 

(Richter and Burrows, University of 

Bremen, 2003) 

Source: http://www-iup.physik.uni- 

bremen.de/ .de/sciamachy/ ) 

OMI 

SCIAMACHY 

6 x higher resolution 

1 day GC 3 day GC 



What are the roles of tropospheric ozone and 

aerosols in climate change ? 

Climate Change 

è Monitoring of global 

(tropospheric) ozone 

distributions from space 

è Monitoring of aerosol 

distributions 

Mean aerosol optical depth in August 1997 (monthly average). 

OMI will achieve a similar spatial resolution. Retrieved from ATSR-2 

image (see Gonzalez et al., Geophys. Res. Lett., 27, 955-958, 2000 ) 



TOMS Aerosol Record 

Data record of aerosol optical thickness over land and oceans 

Covers 1979-1992 1992 (Nimbus 7) and 1996-2002 (Earth Probe) 


P.F. Levelt, KNMI (Royal Netherlands Meteorological Institute) 

see : 

Torres et 

al., JGR, Vol. 103, 

17099-17110, 17110, 

1998 

Torres et al., J. 

Atm. Sci., Vol. 59, 

398-413, 2002

What are the causes of surface UV-B change? 

UV-B change 

305 nm erythemally weighed 

è Monitoring of global 

ozone, cloud and 

aerosol distributions 

from space needed 

Simulated OMI UV products: 

spectral surface Irradiance at 305, 

324 nm, 380 nm and Erythemally 

weighted UV irradiance (UV 

Index). The products were 

simulated using actual TOMS 

Level 2 radiances measured on 

September 3, 1987. 

( N.A. Krotkov et al., 

ATBD-OMI Vol. 3, 2002 ) 

URL: http:// ://eospso.gsfc.nasa.gov/ 

324 nm 380 nm 



OMI Operational Scenario 

• Orbital phase based operations relative to S/C Noon. 

• Monthly operations scenario based on 

Aura orbital repeat cycle. 

• Once per month one 

Idle 

day spatial zoom. 

• One orbit per month 

no Earth msmts. 

• Once per day 

irradiance msmt. 

• 9 orbit types 

• 67 instrument configurations 

• 56 for calibration purposes 

optimized to maintain calibration 

Calibration 

Measurements: 

Dark, WLS, LED 

Idle 

Solar Calibration 

Start Earth measurements 

End Earth 

measurements 

S/C noon 

sun 



Science Data Processing Operations 

L2 O3-profile 

GES DAAC 

L1b (ir)rad 

ODPS 

KNMI 

L1b (ir)rad,cal 

L1b cal 

Analyses 

OMI SIPS 

L1b cal 

Trending Facility 

L1b OPF,AUX 

L1b OPF 

KNMI Server 

EDOS 

L0-RBD 

ONRTS 

RBD-IAM telemetry 

L2 NRT 


P.F. Levelt, KNMI (Royal Netherlands Meteorological Institute) 

US element 

NL element 

MC dataflow 

ME dataflow

OMI Data 

Applications 

OMI 

VFD 

Europe 

NRT 

Global 

DAAC 

& KNMI 

UV UV 

warning 

Air Air 

quality 

Weather 

prediction 

Education 

& outreach 

Climate 

research 

Trend 

analysis 



Summary 

• OMI is the first of the new generation space borne 

spectrometers 

• OMI will significantly contribute to research on 

– climate 

– ozone layer 

– air quality 

• KNMI PI Institute for OMI 

– instrument 

– data products 

– operations 

– validation 

• Aura launch 8 months away 



Backup Slides 



TV#3 PI-activity: zenith sky 

Ozone fits: 

Synthetic slit function used 

Further improvements by 

using measured slit function 

Normalized Radiance 

Example of a DOAS Fit 

Measurement 

Fit 

OMI zenith sky 17-AUG-2002 

Relative Ozone Slant Ozone Column 

[DU] 

3000 

2500 

2000 

1500 

1000 

500 

0 

-0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 

-500 

-1000 

Wavelength [nm] 

Relative ozone slant 

column as function of 

cosine SZA 

-1500 

Cosine of Solar Zenith Angle 



International OMI Project 

Instrument 

Level 0-1b0 

On-ground 

Calibration 

Algorithm 

Development 

In-flight 

Calibration & 

Trend 

Monitoring 

Operations 

QA & 

Validation 

Data 

Processing 

Science 



Aura Instruments 



OMI Science Team 

PK Bhartia US OMI Team Leader Pieternel Levelt OMI-Principal Investigator 

Albert Fleig Dept. TL standard products Bert van den Oord Deputy PI 

Richard McPeters Dept. TL science Pepijn Veefkind Ozone column algorithm 

Lawrence Flynn Ozone algorithm Robert Voors Ozone Profile algorithm 

Jack Fishman Trop. Ozone algorithm Robert Decae Aerosol algorithm 

Kelly Chance Trace gas algorithm Johan de Haan Cloud algorithm 

James Gleason NO2 algorithm Folkert Boersma NO2 algorithm + validation 

Joanna Joiner Cloud algorithm Ellen Brinksma Validation + NO2 algorithm 

Omar Torres Aerosol algorithm Mark Kroon Validation 

George Mount Instrument calibration Ruud Dirksen Instrument calibration. 

Donald Heath Instrument calibration Marcel Dobber Instrument calibration 

Richard Cebula Instrument calibration Johan de Haan Algorithm development 

Arlin Krueger SO2 algorithm Piet Stammes Algorithm development 

Derek Cunnold Ozone validation Gerrit de Leeuw Aerosol algorithm 

Charles Trepte Aerosol validation Roeland van Oss Ozone Profile algorithm 

Ivanka Štajner Data assimilation Jacques Claas OMI operations 

Stanley Sander Spectroscopy + 

Joke van den OMI public outreach 

NO2 validation 

Bovenkamp 

Ernie Hilsenrath US co-PI John van der Vegte OMI data processing 

Wim Som de Cerff OMI data processing 

René Noordhoek OMI scientific secretary 

Hennie Kelder OMI key ST member 

Ilse Aben 

OMI key ST member 

Gilbert Leppelmeier Finnish co-PI Ivar Isaksen OMI key ST member 

Anssi Mälkki Finnish Program Leader Ulrich Platt OMI key ST member 

Esko Kyrö Validation Didier Hauglustaine OMI key ST member 

Aapo Tanskanen Visit TU-Eindhoven, 11 February 2003 Paul Simon OMI Slide key 35 ST member 


Retrieval Methods: DOAS 

DOAS FIT 



Product 

Ozone Column 

Ozone Profile 

Tropospheric Ozone Column 

NO 2 

Column 

SO 2 

Column 

BrO Column 

OClO Column 

HCHO Column 

Aerosol Optical Thickness 

Aerosol Single Scattering Albedo 

Cloud Cover 

Cloud Pressure 

Surface UV-B flux 

Units 

DU 

DU 

DU 

molec/cm 2 

molec/cm 2 

molec/cm 2 

molec/cm 2 

molec/cm 2 

dimensionless 

dimensionless 

dimensionless 

hPa 

Watt/m 2 

Accuracy 

absolute :: relative 

3%::1.5% 

10%::10% 

25%::10% 

30%::20% 

50%::20% (non volcanic) 

25%::25% 

15%::10% 

25%::25% 

30%/0.1::10%/0.05 

0.1::0.05 

0.05:0.05 

100 hPa:: 30 hPa 

10%::10% 



Airborne OMI-UV/VIS 

Spectrometer 

Instrument: OMI Demo Model, VIS spectrometer 

Validation Products: 

Tropospheric and stratospheric 

columns: O 3 , NO 2, HCHO 

Aerosol characteristics 

UV radiances (Level 1) 

UV surface reflectance (RTM) 

Tropospheric pollution research: 

unprecedented resolution and coverage 



The A-Train 



OMI Earth Observing Principle 

2-dimensional CCD 

swath 

~ 580 pixels 

wavelength 

~ 780 pixels 

flight direction 

» 7 km/sec 

viewing angle 

± 57 deg 

12 km/24 km (binned & co-added) 

2600 km 

13 km 

(2 sec flight))

KNMI, P. Levelt II (pdf) - SRON

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