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Introduction

Introduction. Calibration at NPL Summer 2009 Flight campaign Water vapour profiles So preliminary data comparisons Closing remarks. Radiometric calibration. At NPL 5 th - 15 th May 2009 Pre-campaign radiometric calibration with 2 external blackbody sources. NPLxBB and ICxBB .

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Introduction

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  1. Introduction • Calibration at NPL • Summer 2009 Flight campaign • Water vapour profiles • So preliminary data comparisons • Closing remarks CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  2. Radiometric calibration • At NPL 5th - 15th May 2009 • Pre-campaign radiometric calibration with 2 external blackbody sources. NPLxBB and ICxBB. • Differential instrument, always measures the difference between two views. • Temperatures viewed covers those found in flight. • Additional runs with both external blackbodies at near-equal but cold temperatures, to isolate the instrument self-emission term. CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  3. Calibration run targets (2009) CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  4. Summer flying 2009 • 13 July – 12 August 2009 • Based out of Basel, Switzerland • 38.5hrs over 9 flights CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  5. CAVIAR 2008 Flight schedule MC – mountain cloud CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  6. B471 – 27/07/09 Profile 7 ~20kft 09:55UTC Profile 2 ~16kft 07:40UTC Profile 7 ~18kft 09:58UTC CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  7. Elevation data from: http://srtm.csi.cgiar.org/ CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  8. CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  9. Water Vapour profiles • Each group (IC, MO, Reading) involved in the flight campaign need to know the water vapour profile (and uncertainty) to compare with measured spectra. • There are a number of sources of data; dropsonde, models, aircraft in-situ, satellites. • Need to be compared and combined in an intelligent manner. • All participants need to be using same profiles, for better cross-comparison… • Workshop in week 30 Nov – 4 Dec 2009 @ IC involving SN, LT and PG CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  10. Measuring Water Vapour CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  11. Measuring Water Vapour CAVIAR Annual Meeting Cosener’s House,15th Dec 2009

  12. Profile philosophy • Dropsonde are most accurate measures of profile, but only occasional snap-shot. • Aircraft in-situ measurements from frost-point hygrometer, fluorescence WV spectrometer and Nevzorov TWC, all have different response times and measurement characteristics. Provide profiles in ascents/descents and measure of variation along runs. • ECMWF analysis model fields – 0.25° grid assimilating all available data, but produced via spherical harmonics scheme – limited detail. • Swiss Met model • GPS water vapour from JFJ • JFJ surface measurements • Satellite data (SEVIRI, IASI, AIRS etc) • Microwave (MARSS) instrument on FAAM-146 • And radiometer data itself – shouldn’t be forgotten. • So how best to combine… CAVIAR flight debrief (2009) Reading 16th November 2009

  13. Profile philosophy Dropsondes are an accurate snap-shot, ECMWF, even if biased, should give good idea of trend, temporally and spatially. Aircraft in-situ measurements as first check of this. Initially: • define a few points fixed points, representative of segments of the run (Camborne – Ocean N, Camborne, Ocean S). In this case, NW-SE runs, fortuitously follows ECMWF grid diagonal. • Sonde drop locations, naturally cluster about these points – so attribute dropsonde data to these locations. • Look at time of ECMWF fields analysis/forecast, dropsonde launch and aircraft run pass. Interpolate the ECMWF fields in time between these epochs, and produce a shift in T(p),q(p) from change in ECMF field. So, any good? CAVIAR flight debrief (2009) Reading 16th November 2009

  14. Time variance of assimilation CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  15. Comparison of ECMWF correct profiles CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  16. B471 Run 1 CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  17. B471 Run 1 CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

  18. Closing remarks • Overall a very successful campaign. Best yet in terms of weather, instrument performance (TAFTS and others) and number of flights • But lots to do… • Concentrate on B471. • Continue analysis of dropsonde / Payerneradiosonde data. • Determine most appropriate profile for each run – last week. • Calibrate B471 runs 2,3,4,5 and 6. • Compare with ARIES data (in cross-over region). • Uncertainty budget calculations with updated ε and ΔT from NPL-based calibration work. • LBL code updates – HITRAN2008 / Tennyson list. • Make continuum assessment, then validate with other flights. CAVIAR Annual Meeting Cosener’s House,14th Dec 2009

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