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Long-term water vapour comparison at the ARM Mobile Facility. S. Crewell, U. Löhnert, S. Kneifel (U Cologne) D. Turner (U Wisconsin). Instrumentation at AMF. Radiosondes IfT Lidar Microwave Radiometers - MWRP 12 ch. - HATPRO - Scanning (Köln) - MWRLOS 2ch. - MWRHF - DPR GPS. Vertical
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Long-term water vapour comparison at the ARM Mobile Facility S. Crewell, U. Löhnert, S. Kneifel (U Cologne) D. Turner (U Wisconsin)
Instrumentation at AMF • Radiosondes • IfT Lidar • Microwave Radiometers- MWRP 12 ch.- HATPRO - Scanning (Köln)- MWRLOS 2ch.- MWRHF - DPR • GPS Vertical profiles Integrated Water Vapor (IWV) HATPRO DPHASE MWRP MWRLOS MWRHF
standard atmosphere temperature profilehumidity profile Microwave Signatures liquid water path LWP=250 gm-2
Difference in gas absorption from MonoRTM - Rosenkranz TB Intercomparison continuum at higher freqs 22 GHz water vapor line
Radiosonde Dry Bias AMF April to June Bias/Std. Deviation in Integrated Water Vapor in kg m-2
Scanning Microwave Observations COPS: Azimuth scans every 15 min - fixed elevation angle (30°) - 355°- rotation with 5° resolution - beamwidth: HATPRO: ~4-2°, IR: ~1° - scan duration about 5 Min. Integrated Water Vapor (IWV), liquid water path (LWP) and IR-Temperatur along slant path for each azimuth angle
Exmple: 14 July 2007 30 deg azimuth scans • Morning strong asymmetry of thehumidity field • Noonstrong humidity reductionof about 5 kgm-2 (in zenith) • 13:00-14:30 UTCConvection in the North West • after 15:00humidity increase see Poster by S. Kneifel
Summary and Outlook • Water vapour absorptionPoorly known at higher microwave frequencies calibration analysis • Integrated Water Vapor consistent analysis of all COPS microwave radiometers (calibration, filtering, quality flags, retrieval algorithms..) • Profiles intercomparisons with IfT Lidar, DLR aircraft lidar • Spatial variabiityMore than 10 % variabilty in IWV(see Poster by Kneifel further analysis of volume scans