gome-2 fm3 (metop-a) instrument review, eumetsat, darmstadt, june 2012 slide: 1 rűdiger lang, rose...
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GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 1
Rűdiger Lang, Rose Munro, Antoine Lacan, Richard Dyer, Marcel Dobber, Christian Retscher, Gabriele Poli, and Michael Grzegorski EUMETSAT
GOME-2 AIRR:Angular dependence of the GOME-2 solar irradiance (AIRR)
On-ground versus On-Board modelling
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 2
AIRRWhat is the AIRR
elevation
Azi
mu
th
On-ground In-Orbit
elevation
Azi
mu
th
Se
as
on
Daily Sun Meas. Sequence
Instrument set-up layout, courtesy: TNO
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 3
AIRRWhat is the AIRR
elevation
Azi
mu
th
On-ground
Discretisation Settings:On-ground results (example):
Instrument set-up layout, courtesy: TNO
FM3:
Azimuth: 5 degrees(-317 to 333)Elevation: 0.75 degrees(-1.5 to 1.5)
FM2:
Azimuth: 2 degrees(-316.3 to 333.3)Elevation: 0.1 degrees(-1.5 to 1.5)
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 4
AIRRSpecifications for FM-3/PGS 7 – Key-data for MME1,irr
PGS 7 page 96 and A.2.0.4 (page 75)
RA_ABS_IRR_MAIN.203
BSDF_AIRR.203
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 5
AIRRSpecifications for FM-3/PGS 7 – Angle grid
PGS 7 page 87
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 6
AIRRSimulation set-up
Offline simulation of AIRR using EUM and FM2, as well as high resolution settings:
• High res. elevation grid (all): -1.5 to +1.5 at 0.1 degrees fixed gridInterpolated per individual solar measurement period from real elevation grid
• Medium res. FM2 SAA grid: 316.7 to 333.3 at 2 degrees grid (c.f. 5 degrees for FM3)
Interpolated from all 365 solar measurements between June 2010 and June 2011.
• High res. SAA grid: 316.7 to 333.3 at 0.5 degrees grid (c.f. 5 degrees for FM3)
Interpolated from all 365 solar measurements between June 2010 and June 2011.
• AIRR ( C (j,e) ) is derived from raw calibrated signals and offline corrected for Dark current, normalised per integration time, Etalon, and PPG such that:
C (j,e) = SDNEP(j,e) / SDNEP (j=325,e=0) • For cross-checking the same is done with “half-calibrated spectra”
SDNSE(j,e)/Mirr,1 and compared to original PPF-L1B data.
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 7
AIRRSimulation reference period
Reference period has been shifted from 2007 (previous analysis) to June 2010-June 2011
2010/11 provides a much more quieter period (no instrument anomalies or switch-offs) with smaller degradation rate and better consistence between main channels and PMD
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 8
AIRRDisclaimer
1. Sorry! Its a 4D problem (I, ,j e,l)!
2. All results are preliminary awaiting approval by level-2 retrievals!
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 9
AIRR – The angular resolution problemMeasurements at FM3/Metop-A key-data elevation grid – operational setup
Band 3 at 420 nm
On-boardElevation:
FM3 situation !
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 10
AIRR – The angular resolution problem Measurements at high res. fixed elevation grid – offline setup
Band 3 at 420 nm
On-BoardElevation:
High- resolution/FM-2situation !
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 11
AIRR – The angular resolution problem Comparison between current key-data and high res. elevation angle grid
Elevation:Key-data – FM3 setup
Elevation:OnBoard – High resolution/FM2 setup
Band 3 at 420 nm
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 12
AIRR – derived from 2007Measurements at high res. fixed azimuth grid – offline setup without de-trending
Band 3 at 420 nm
Azimuth:On-Board
The zigzag features are the results of continuous degradation in combination with different SAA measured at different times throughout the year!
Year 2007
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 13
AIRR – derived from 2010/11Measurements at high res. fixed azimuth grid – offline setup without de-trending
Band 3 at 420 nm
Azimuth:On-Board
Less zigzag because of smaller degradation rate throughout the year 2010/11!
Year June 2010-June 2011
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 14
AIRRDe-trending of results during 2011 – Band 3 / Channel 3
• Signals are de-trended subtracting a simple (robust) linear gradient. • June 2007 is used as reference point• Previously the year 2007 was used which a much less stable situation and non-linear
degradation -> introduction of lots of artefacts in the de-trending
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 15
AIRRDe-trending of results during 2011 – Band 3 / Channel 3
• Signals are de-trended subtracting a simple (robust) linear gradient. • June 2007 is used as reference point• Previously the year 2007 was used which a much less stable situation and non-linear
degradation -> introduction of lots of artefacts in the de-trending
[ show results per wavelength for de-trending]
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 16
AIRRMeasurements at FM-2 2.0 degree azimuth grid – offline setup de-trended
Band 3 at 420 nm
Azimuth:On-Board
De-trended signals for June 2010 to June 2011 at FM2-2 campaign resolution of 2.0 degrees for SAA
June 2010 to June 2011
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 17
AIRRMeasurements at High. Res. 0.5 degree azimuth grid – offline setup de-trended
Band 3 at 420 nm
Azimuth:On-Board
De-trended signals for June 2010 to June 2011 at FM2-2 campaign resolution of 2.0 degrees for SAA
June 2010 to June 2011
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 18
AIRR – Recommendation for future CampaignsAIRR simulation at different resolutions – Band 3
SAA: 0.5 resolution (317 to 333)Elevation: 0.1 resolution (-1.5 to 1.5)Similar to L1-processor angle fine-grid as defined in initialisation file!
Better discretisation balance!
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 19
AIRRFM2 calibration campaign settings – FM2 /Metop-B key-data set
For the FM2-2 calibration campaign the following settings have been implemented:
• SAA: 2 degree resolution (316.7, 317 to 333, 333.3)• Elevation: 0.1 degree resolution (-1.5 to 1.5)
The recommended SAA resolution of 0.5 degrees could not be implemented because of time and stability constraints.
• This has been regarded as an acceptable compromise between time constraints and expected accuracy at the point of the decision in February 2011 (considering the lower frequency structures observed in SAA)
• For the future the measurement at 0.5 degrees is highly recommended
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 20
AIRRResults for detrended high-resolution AIRR from GOME-2 measurments 2010/2011
Band 3 at 420 nm
On-BoardElevation:
High- resolution/FM-2situation !
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 21
AIRRResults for detrended high-resolution AIRR from GOME-2 measurments 2010/2011
Band 3 at 420 nm
On-BoardAzimuth:
High- Resolution (recommended)
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 22
AIRR – Results On-Ground VS On-BoardSimulated and key-data derived MME1,irr
Band 3 at 420 nm
From key-data
Simulated from 1 year of solar measurements2010/2011
On-ground vs.On-BoardAzimuth/elevation:
High- Resolution 0.5/0.1 degrees
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 23
AIRR – Results On-Ground VS On-BoardSimulated and key-data derived MME1,irr
Channel 3
From key-data
Simulated from 1 year of solar measurements2010/2011
On-ground vs.On-Board
Relative toElevation = 0
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 24
AIRRApplication of modelled AIRR (de-trended) to Solar Mean Reference spectra
17th October 2007
On-ground On-board – New AIRR
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 25
AIRRApplication of modelled AIRR (de-trended) to Solar Mean Reference spectra
17th October 2007
On-ground vs.On-BoardderivedAIRR
Impact on SMR main channel data
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 26
AIRRApplication of modelled AIRR (de-trended) to Solar Mean Reference PMD spectra
17th October 2007
On-ground vs.On-BoardderivedAIRR
Impact on SMR PMD P-to-S ratio data
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 27
AIRRApplication of modelled AIRR (de-trended) to Solar Mean Reference PMD spectraImpact on level 2 (preliminary!)17th October 2007
On-ground vs.On-BoardderivedAIRR
Impact on ozone total column using GDOAS(Courtesy: O3MSAF/BIRA)
O3 (new AIRR) – O3 (FM3 key-data) [%]
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 28
AIRRApplication of modelled AIRR (de-trended) to Solar Mean Reference PMD spectraImpact on level 2 (preliminary!)17th October 2007
On-ground vs.On-BoardderivedAIRR
Impact on NO2 total column using GDOAS(Courtesy: O3MSAF/BIRA)
NO2 (new AIRR) – NO2 (FM3 key-data) [%]
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 29
AIRRApplication of modelled AIRR (de-trended) to Solar Mean Reference PMD spectraImpact on level 2 (preliminary!)17th October 2007
On-ground vs.On-BoardderivedAIRR
Impact on NO2 total column using GDOAS(Courtesy: O3MSAF/BIRA)
BrO (new AIRR) – BrO (FM3 key-data) [%]
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 30
AIRRConclusions and Recommendations
Overall:The impact of the difference between in-orbit modelled AIRR and the one that has been delivered in the key-data on the mean solar reference spectrum is small. But the spectral features are probably non-negligible and the impact may be different at various times per year (not fully investigated yet!).
Preliminary: The impact on level-2 retrievals varies with the significance of the spectral features. Impact on TO3 is small whereas the impact on TNO2 and TBrO seems to be quite significant
Recommendation: 1. To measure the AIRR on-ground on a 0.5 resolution grid for
SAA and on a 0.1 resolution grid for elevation angle.
2. To smooth the data in spectral space and to improve on removal of “etalon-type” wiggles.
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 31
AIRRConclusions and Recommendations
The end
GOME-2 FM3 (Metop-A) Instrument Review, EUMETSAT, Darmstadt, June 2012 Slide: 32
NOAA results by Larry Flynn (41st GSAG)
EAST
Version 8 331-nm Reflectivity for a box in the
Equatorial Pacific.
The unadjusted values in the top plot reach a
minimum of 8% (higher than expected for the open ocean) for the Nadir scan
position.
A single calibration adjustment lowers this value to 4% and also flattens out the scan
dependence for West-viewing positions. The
East-viewing results are not as good.
|Lat|<5Lon<-100
WEST
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