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© Crown copyright Met Office CAVIAR field campaigns meeting Stuart Newman Exeter, 29 April 2010
© Crown copyright Met Office Contents This presentation covers the following areas NPL laboratory calibrations Field campaign profile selection Initial continuum results
© Crown copyright Met Office NPL lab calibrations
© Crown copyright Met Office CAVIAR work package 3.2 Low temperature blackbody calibration ARIES calibrated against NPL low temperature blackbody Range of temperatures relevant to atmospheric remote sensing – we achieved a range of -75 to +30 ºC ARIES blackbody target temperatures also varied as a test of target emissivity
© Crown copyright Met Office ARIES target emissivity tests Positive bias with hot target at 81ºC, cold target at 20ºC Negative bias with hot target at 12ºC, cold target at 41ºC (c.f. NPL target with 0.9975 emissivity at -74.8ºC)
© Crown copyright Met Office Finding best fit target emissivities
© Crown copyright Met Office ARIES target emissivity results hot target at 81ºC, cold target at 20ºC hot target at 12ºC, cold target at 41ºC
© Crown copyright Met Office Merge results ExperimentNPL target temperature Fitted (CBB)Fitted (HBB) N004 22 May 09 -45ºC0.9930.996 N005 26 May 09 -75ºC0.9800.992 N006 27 May 09 -75ºC0.9760.992
© Crown copyright Met Office Account for calibration uncertainty?
© Crown copyright Met Office Best estimate for uncertainty? Standard deviation gives very large uncertainty Standard deviation of mean (standard error) reduces this by N but for 500-1000 measurements this is an over-constraint May be appropriate to use number of independent calibrations (blackbody views) as N, approx. 20-30 per set of conditions Mean & std. dev.
© Crown copyright Met Office Field campaign profile selection
© Crown copyright Met Office Summary of flights FlightDateWeather conditionsComments B466 16.07.09Cloud at times over JungfraujochPartial NPL data B467 19.07.09Initially thin cirrus which clearedGood NPL data B468 20.7.09Good clear sky conditionsFLASH sonde* + MetOp overpass B469 25.07.09Cloud at times over JungfraujochPartial NPL data B470 26.07.09Some thin cirrus encroachingGood NPL data B471 27.07.09Excellent clear sky conditionsMetOp overpass B472 29.07.09Excellent clear sky conditionsARIES failure B473 01.08.09Excellent clear sky conditionsNo TAFTS B474 04.08.09Partial cloud over JungfraujochCancelled am flight, pm only * Institute of Applied Physics in Bern launch radiosondes from Payerne equipped with RS92, Snow White and FLASH-B (Lyman-alpha) hygrometers
© Crown copyright Met Office Meeting at IC in December Identify sources of profile information (dropsondes, aircraft probes, model fields) Agree a method for sub-selecting data (three areas: NW, over JFJ & SE, different profile for each aircraft run) Agree a method for combining profile information (as a first attempt use the nearest co-located dropsonde and perturb using model spatial-temporal evolution… however, see next slides)
© Crown copyright Met Office Model biases Statistics of model fields versus 55 dropsondes ECMWF mean biases are small (though with large scatter) Cosmo mean biases are larger, particularly for humidity
© Crown copyright Met Office Model biases cont. Really bad example for Cosmo
© Crown copyright Met Office Model biases cont. Better example for Cosmo Cosmo particularly bad on 27/7/09 and 1/8/09 (for some reason) So far have used ECMWF exclusively
© Crown copyright Met Office Profile issues Using model to evolve dropsonde profile only works if model is close to true atmosphere If model biases are present, and profile is extrapolated too far in time and space, errors can be introduced It seems best to concentrate first on situations where the spectrometer data are closely located with a dropsonde (or aircraft profile)
© Crown copyright Met Office Can we use FWVS data? Dropsondes are widely recognised as most accurate source of humidity data from the aircraft However, for runs immediately after a profile descent (e.g. 35000 ft down to 15000 ft) FWVS may be more representative Attempt to use FWVS humidity data in LBLRTM simulations of ARIES at 15000 ft
© Crown copyright Met Office CAVIAR example B467 19-Jul-2009 Initial run at high level for radiance measurements (here looking up) Spiral descent over Jungfraujoch observatory measuring in situ water vapour (rapid response FWVS probe used here) Subsequent run at lower level for radiance measurements (here looking up) Determine change in radiance due to water vapour in atmospheric path Derive continuum strength, compare to MT_CKD model in LBLRTM
© Crown copyright Met Office CAVIAR example B467 19-Jul-2009 Consistent discrepancy in centre of water vapour band for channels at 1586 and 1598 cm -1 (MT_CKD continuum is relatively strong at 1586 cm -1 compared with measurements)
© Crown copyright Met Office Humidity information from MARSS Helpful to constrain humidity above the aircraft using microwave observations at 183 GHz Microwave Airborne Radiometer Scanning System (MARSS)
© Crown copyright Met Office MARSS humidity channels B467 (19/7/09) Good agreement for channel centred closest to 183 GHz line B471 (27/7/09) Worse agreement for channel 183±1 GHz, better for 183±3 GHz
© Crown copyright Met Office CAVIAR example B471 27-Jul-2009 Inconsistent results here, all retrieved continuum strengths < MT_CKD Is this because LBLRTM profile is too moist? Possible to use MARSS data for profile constraint?
© Crown copyright Met Office Initial continuum results from Jungfraujoch flights and satellite data
© Crown copyright Met Office 8 MetOp cal/val flights Sea – Gulf of Mexico Land – Oklahoma 2 night, 6 day flights All MetOp collocated Joint Airborne IASI Validation Experiment (JAIVEx) – April-May 2007
© Crown copyright Met Office IASI water vapour band Flight B290, 30-Apr-2007
© Crown copyright Met Office IASI water vapour band Flight B285, 19/20-Apr-2007
© Crown copyright Met Office IASI water vapour band Flight B290, 30-Apr-2007 Coudert et al. water vapour spectroscopy updates since HITRAN2004 MT_CKD_2.5 in LBLRTM_v11.7 Continuum channels relatively insensitive to spectroscopic database
© Crown copyright Met Office IASI water vapour band Implied continuum strength is less than MT_CKD 1900 cm -1 Retrieved continuum is sensitive to uncertainties in atmospheric profile
© Crown copyright Met Office Preliminary results Selected data from flights B467-B474
© Crown copyright Met Office Questions and answers
© Crown copyright Met Office IASI atmospheric retrieval
© Crown copyright Met Office Spectral retrieval
© Crown copyright Met Office CAVIAR field campaigns update Stuart Newman UCL, 13 May 2010.
© Crown copyright Met Office Update on CAVIAR field experiments Stuart Newman NPL, 29 September 2010.
© Crown copyright Met Office CAVIAR Update to Met Office work on field campaigns Stuart Newman Imperial College, 29 March 2011.
© Crown copyright Met Office CAVIAR ARIES water vapour continuum results Stuart Newman Reading, 6 December 2010.
CAVIAR flights 9 flights Runs 15,000 to 35,000 feet Spiral descents over Jungfraujoch Dropsondes from high level MetOp underflights FL150 FL350.
© Crown copyright Met Office Mid-infrared observations of the water vapour continuum from CAVIAR field campaigns Stuart Newman and co-workers Coseners.
© Crown copyright Met Office Initial assessment of ARIES continuum measurements Stuart Newman Imperial College, 16 December 2008.
© Crown copyright 2007 CAVIAR flight plans Stuart Newman, Met Office, Exeter, UK.
TAFTS: Comparing Uncertainties in Atmospheric Profiles with the Water Vapour Continuum Ralph Beeby, Paul Green, Juliet Pickering, John Harries.
TAFTS: Atmospheric Profile Uncertainty and Continuum Contribution Ralph Beeby Paul Green, Juliet Pickering 29 th September 2010.
© Crown copyright Met Office First look at Camborne data Stuart Newman Reading, 25 November 2008.
© Crown copyright Met Office An update on plans for CAVIAR field campaigns Stuart Newman NPL, 2 June 2008.
© Crown copyright Met Office STICCS science aims Stuart Fox, Chawn Harlow, Clare Lee, Patrick Eriksson, Eric Defer + others…
TAFTS: CAVIAR field data from Camborne 2008 Ralph Beeby, Paul Green, Juliet Pickering, John Harries.
CAVIAR Field Campaign Meeting, Imperial College 29/3/11 TAFTS: Water Vapour Continuum Data from the 2008 CAVIAR Field Campaign Ralph Beeby, Paul Green,
CAVIAR Annual Meeting Cosener’s House,14 th Dec 2009 Page 1 Introduction Calibration at NPL Summer 2009 Flight campaign Water vapour profiles So preliminary.
© Crown copyright Met Office Overview of Camborne field campaign Stuart Newman Imperial College, 16 December 2008.
Infrared Interferometers and Microwave Radiometers Dr. David D. Turner Space Science and Engineering Center University of Wisconsin - Madison
© Crown copyright Met Office SALSTICE: the aircraft and ground based campaign in USA (May 2013) Stu Newman, Chawn Harlow and co-workers OBR conference,
Page 1© Crown copyright 2004 Cirrus Measurements during the EAQUATE Campaign C. Lee, A.J. Baran, P.N. Francis, M.D. Glew, S.M. Newman and J.P. Taylor.
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