Post on 15-Jan-2016
description
COPS Workshop, 27-29 February 2008
Long-term water vapour comparison at the ARM Mobile Facility
S. Crewell, U. Löhnert, S. Kneifel (U Cologne) D. Turner (U Wisconsin)
COPS Workshop, 27-29 February 2008
Instrumentation at AMF Radiosondes
IfT Lidar
Microwave Radiometers
- MWRP 12 ch.
- HATPRO - Scanning (Köln)
- MWRLOS 2ch.
- MWRHF
- DPR
GPS
Vertical profiles
MWRPMWRLOSMWRHF
HATPRODPHASE
Integrated Water Vapor (IWV)
COPS Workshop, 27-29 February 2008
Data SetSource Org. Description t Operation
COSMO-DE DWD Model analysis/fore-cast at 3x3 gpoints
15 min 04/01-12/ 31
RS-92 ARM Radiosonde profiles 919 quality checked
4 / day 04/01-12/ 31
GPS GFZ 15 min, 93% 15 min 04/19-12/31
2CH ARM Standard ARM dual channel radiometer
20 s 04/01 - 12/31
MWRP ARM 12 freqs 1 s 04/01 - 12/31
MWRHF ARM 90/150 GHz 1 s 06/20-12/31
HATPRO UKöln scanning 14 freqs 04/20-12/31
DPR UKöln dual pol at 150 GHz 1s 05/02-10/05
Lidar IfT Raman COPS
MSG FUB IWV 3x3 grid 15 min 04/01-12/31
COPS Workshop, 27-29 February 2008
Microwave Signatures
standard atmosphere
liquid water pathLWP=250 gm-2
temperature profilehumidity profile
ν /GHz 31 36 90
90° 9 12 50
COPS Workshop, 27-29 February 2008
TB Intercomparison
Difference in gas absorption from MonoRTM - Rosenkranz
22 GHz water vapor line
continuum at higher freqs
COPS Workshop, 27-29 February 2008
Radiosonde Dry Bias
0 UTC 6 UTC 12 UTC 18 UTC All
N 61 66 68 65 263
RS - GPS 0.3 1.1 -0.1 0.8 -1.5 1.3 -0.3 0.8 -0.4 1.2
RS - Profiler 0.0 0.8 -0.7 0.7 -1.0 0.7 -0.4 0.6 -0.5 0.8
RS - 2 ch 0.2 0.5 -0.5 0.6 -1.4 0.9 -0.6 0.6 -0.6 0.9
AMF April to JuneBias/Std. Deviation in Integrated Water Vapor in kg m-2
COPS Workshop, 27-29 February 2008
Scanning Microwave ObservationsCOPS: 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-Temperaturalong slant path for each azimuth angle
COPS Workshop, 27-29 February 2008
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
COPS Workshop, 27-29 February 2008
Summary and Outlook
Water vapour absorption Poorly 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