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© Crown copyright Met Office CAVIAR Update to Met Office work on field campaigns Stuart Newman Imperial College, 29 March 2011.

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Presentation on theme: "© Crown copyright Met Office CAVIAR Update to Met Office work on field campaigns Stuart Newman Imperial College, 29 March 2011."— Presentation transcript:

1 © Crown copyright Met Office CAVIAR Update to Met Office work on field campaigns Stuart Newman Imperial College, 29 March 2011

2 © Crown copyright Met Office Contents This presentation covers the following areas New data Recent work on Camborne B400 case study Improved ARIES profile retrievals CAVIAR 1.0 continuum in LBLRTM Agreement/discrepancies in continuum coefficients

3 © Crown copyright Met Office Recap on ARIES case study data CampaignGood ARIES nadir data?Good ARIES zenith data? Camborne (field of view mis-pointing corrected end 2008) Jungfraujoch Result: lack of data sensitive to the self-broadened continuum in range cm -1 Also desirable to have night-time data to probe spectrum > 2000 cm-1 contaminated by solar radiation in daytime

4 © Crown copyright Met Office New flights during FAAM detachment to Exeter airport CAVIAR evening flight on 7 March VACAR-CAVIAR evening flight on 18 March ARIES performed mostly ok…

5 © Crown copyright Met Office Very preliminary analysis Very dry layer

6 © Crown copyright Met Office Very preliminary analysis Orbits to increase zenith slant path

7 © Crown copyright Met Office Very preliminary analysis

8 © Crown copyright Met Office Very preliminary analysis

9 © Crown copyright Met Office Very preliminary analysis Reduce bias with better T- dependence?

10 © Crown copyright Met Office B400 case (18/9/2008) revisited Look again at retrieving profile information from ARIES monomer channels Characteristics of background errors (matrix of error covariances for temperature and humidity) very important B-matrixAdvantagesDisadvantages ECMWFwell-tested in NWPinflexible, global average toy modelflexiblemay not be realistic campaign- specific directly applicable to case study need good statistics

11 © Crown copyright Met Office Error covariance estimates from dropsondes and radiosondes

12 © Crown copyright Met Office Error covariance estimates from dropsondes and radiosondes Large variance in humidity

13 © Crown copyright Met Office Error covariance estimates from dropsondes and radiosondes Diagonal contains variances 2 : level i versus level i Off-diagonals are covariances ij : level i versus level j

14 © Crown copyright Met Office Error covariance estimates from dropsondes and radiosondes Large variance in humidity near 400 hPa

15 © Crown copyright Met Office Error covariance estimates from dropsondes and radiosondes Can also compute T-q covariances T(level i) versus q(level j)

16 © Crown copyright Met Office ARIES B400 retrievals Temperature

17 © Crown copyright Met Office ARIES B400 retrievals Humidity

18 © Crown copyright Met Office ARIES B400 retrievals Spectral channels used (CO 2 and H 2 O monomer)

19 © Crown copyright Met Office So… in theory now have a better baseline profile of temperature and humidity to probe continuum channels ARIES B400 retrievals

20 © Crown copyright Met Office ARIES B400 foreign continuum Obs-calc residuals are within ± 2 K for continuum-sensitive channels (with LBLRTM as simulation using MT_CKD 2.5)

21 © Crown copyright Met Office Continuum coefficients including ARIES Jungfraujoch results

22 © Crown copyright Met Office Continuum coefficients ARIES nadir data from Camborne in better agreement with MT_CKD and Igor/RAL than Jungfraujoch zenith data outliers

23 © Crown copyright Met Office Continuum coefficients Satellite (IASI) data from Camborne and Jungfraujoch also in reasonable agreement with MT_CKD and Igor/RAL outliers

24 © Crown copyright Met Office CAVIAR 1.0 continuum Thanks to Igor for supplying coefficients Relatively big changes

25 © Crown copyright Met Office Putting new CAVIAR continuum in LBLRTM Interpolate continuum coefficients to 1 cm -1 resolution (instead of 10 cm -1 ) Replace foreign-broadened and self-broadened (260 K and 296 K) coefficients in range cm -1 as supplied by Igor Seems to run!

26 © Crown copyright Met Office ARIES B400 continuum 1950 cm -1 region stands out

27 © Crown copyright Met Office And finally… far longwave ARIES data Positive bias < 700 cm -1

28 © Crown copyright Met Office Reference with NPL data ARIES performance falls off < 700 cm -1

29 © Crown copyright Met Office Summary and things to do New profile retrievals using ARIES monomer channels, seems to produce better fit to data Water vapour continuum coefficients retrieved from ARIES/IASI nadir data in range cm -1 are in fairly close agreement with Igor/RAL data, except around 1950 cm -1 where discrepancy is unexplained – able to compare with NPL-FTS data? Continuum coefficients from Jungfraujoch data are still smaller; need to reanalyse these data using ARIES retrievals (as above) Igor/RAL continuum coefficients included in LBLRTM at 1 cm -1 resolution, this seems to work without slowing down program ARIES data at extreme longwave end (overlap with TAFTS) are subject to noise/bias, need to quality control carefully

30 © Crown copyright Met Office Questions and answers

31 © Crown copyright Met Office Field campaign summary: UK (Camborne), Switzerland (Jungfraujoch) FlightDateWeather conditionsNotes B Persistent boundary layer cloudPartial NPL data B Persistent boundary layer cloudPartial NPL data B Good clear sky conditionsSonde chase, good flight B Cloud at times over JungfraujochPartial NPL data B Initially thin cirrus which clearedGood NPL data B Good clear sky conditionsFLASH sonde + MetOp overpass B Cloud at times over JungfraujochPartial NPL data B Some thin cirrus encroachingGood NPL data B Excellent clear sky conditionsMetOp overpass B Excellent clear sky conditionsARIES failure B Excellent clear sky conditionsNo TAFTS B Partial cloud over JungfraujochCancelled am flight, pm only

32 © Crown copyright Met Office Very preliminary analysis

33 © Crown copyright Met Office CAVIAR 1.0 continuum Thanks to Igor for supplying coefficients


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