N. Blond, LISA/KNMI P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI
description
Transcript of N. Blond, LISA/KNMI P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI
Evaluation of model simulations with satellite observed NO2 columns and
surface observations&
Some new results from OMI
N. Blond, LISA/KNMI
P. van Velthoven, H. Eskes, F. Boersma, R. van der A, P. Levelt, KNMI
M. van Roozendael, I. De Smedt, BIRA-IASB
EUMETNET-EEA, Copenhagen, 7-8 April 2005
Combining retrieval, modelling and assimilation to obtain NO2 tropospheric columns from SCIAMACHY/GOME
Careful treatment needed for:• Clouds• Surface albedo• Profile shape
(TM)
Validation of (stratospheric) NO2 columns with ground-based observations
Good agreement in remote areasDeviations in industrialised (as expected)
Combined retrieval - modelling - assimilation approach
to GOME NO2
30 x 60 km2
Chimère model
Developed in FranceR. Vautard, H. Schmidt, L. Menut, M. Beekman, N. Blond, ... )Operational air-quality forecasts: www.prevair.org
Model ingredients:• MELCHIOR chemistry (82 species, 333 reactions) • EMEP emissions• ECMWF meteorological analyses• 15 vertical layers, surface - 200 hPa• Boundary conditions from MOZART monthly-mean climatology
Emissions (EMEP)
Motivation• Lack of NO2 profile observations for validating SCIAMACHY. Intermediate step: compare to a model Approach• Space-time co-location of Chimère output with individual
“cloud-free” SCIA pixels• Use averaging kernels from SCIAMACHY: Modelled column = SCIAMACHY kernel vector • model profile• 1 year of SCIAMACHY data - 2003Advantages• Comparison model-SCIAMACHY under exactly same conditions• Comparison independent of profile shape assumptions in retrieval
Motivation for comparison of Chimere with both ground-based and satellite obs
Comparison of Chimère to surface observations
Netherlands rural stations:Bias 0.1 ppb, RMS 7.2 ppb, Correlation 0.66
-- surface obs-- Chimère
SCIAMACHY vs. Chimère: yearly mean
Yearly-mean bias = 0.2 1015 molec. cm-2, RMS 2.9, correlation 0.73Cloud-free pixels only
SCIAMACHY vs. Chimère: 27 Feb 2004
SCIAMACHY vs. Chimère: 28 Mar 2004
Conclusions of evaluationSCIAMACHY-Chimère- surface obs
• Yearly mean: - very small bias SCIAMACHY - Chimère and Chimère - surface - Correlation coefficients ~0.7
• NO2 plumes similar
• Differences in details: - Seasonality (Chimère higher in winter) - Individual days - Detailed distribution
Planned KNMI web service:Surface - Chimère - satellite
New results from the Ozone Monitoring Instrument (OMI)
OMIOMI
MLSMLS
HIRDLSHIRDLS
TESTES
Launched: 15 July 2004 on EOS-AURA
OMI results: NO2
Courtesy: Pepijn Veefkind
13 x 24 km2 with daily global coverage
cloudcloud
OMI results: SO2 (Carn et al.)
Galeras and Tungurahuavolcanoes
La OroyaCu-smelter
Ilo Cu-smelter
Jan 2005G&T: 5300 td-1
Or: 500 td-1
Ilo: 1250 td-1
OMI results: formaldehyde
Internet addresses
Satellite productswww.gse-promote.orgwww.temis.nl
OMIwww.knmi.nl/omi eos-aura.gsfc.nasa.gov
Spare slides
NO2 column retrieval approach
Air-mass factor calculation• Temperature correction (NO2 cross section)• TM4 global chemistry transport model (profiles)• Assimilation of slant columns -> stratospheric "background"• Fresco cloud fraction and cloud top pressure retrieval• TOMS / GOME combined albedo map (Herman, Koelemeijer)• DAK RTM height-dependent AMF lookup table• Tropospheric AMF based on TM profile shape, clouds
Output• Detailed error estimates• Averaging kernels
SCIAMACHY vs. Chimère: 16 April 2004
SCIAMACHY vs. Chimère: 16 Sept 2004
Satellite instruments providing NO2 columns
GOME (April 1995, ERS-2, 40 x 320 km2) SCIAMACHY (February 2002, ENVISAT, 30 x 60 km2) OMI & TES (15 July 2004, EOS-AURA, 13 x 24 km2)
OMI measurement principle
13 km
(2 sec flight))2600 km
12 km/24 km (binned & co-added)
flight direction» 7 km/sec
viewing angle± 57 deg
2-dimensional CCD
wavelength ~ 780 pixels
swath~ 580 pixels
OMI properties UV and VIS backscatter spectrophotometer (270 - 500 nm)
Wide swath (2600 km) telescope yields daily global maps
Resolution of 13 x 24 km2 is best ever for air quality applications
Products: Ozone: total and tropospheric columns, profiles NO2 columns HCHO columns SO2 columns & Clouds (coverage, top pressure), Aerosols,
BrO, OClO, Surface UV Irradiance