1. © Crown copyright Met Office CAVIAR field campaigns update Stuart Newman UCL, 13 May 2010

2. © Crown copyright Met Office Initial continuum results from Jungfraujoch flights

3. © 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

4. © 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

5. © 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

6. © 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)

7. © 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)

8. © 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

9. © 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?

10. © Crown copyright Met Office Preliminary results Selected data from flights B467-B474

11. © Crown copyright Met Office Plausible results? Rowe PM and Walden VP: "Improved measurements of the foreign-broadened continuum of water vapor in the 6.3 mcr band at -30 o C", Applied Optics, 48(7), 1358-65 (2009).

12. © Crown copyright Met Office Plausible results? Paynter D, Ptashnik I, Shine K, Smith K, McPheat R, Williams R: "Laboratory measurements of the water vapor continuum in the 1200 - 8000 cm -1 region between 293 K and 351 K", J. Geophys. Res., 2009

13. © Crown copyright Met Office Towards a conclusion… Groups at Exeter, Imperial College, Reading and NPL will coordinate efforts on two flights where all have good data and atmospheric profile data are reliable Same profile and same underlying radiative transfer model used to ensure consistency Flight B400 on 18/9/2008 over Camborne Flight B467 on 19/7/2009 over Jungfraujoch Move towards synthesis with theoretical and laboratory studies

14. © Crown copyright Met Office Questions and answers