RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Performance of water vapor radiometers at 22 Performance of water vapor radiometers at 22 and 183 GHz developed at RPGand 183 GHz developed at RPG
Thomas Rose, Harald Czekala (Thomas Rose, Harald Czekala (Radiometer Physics GmbH)Radiometer Physics GmbH)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Microwave BandsMicrowave BandsFrequencies:
Humidity Profiling: 22-31.4 GHz Band (7 channels)
LWP / IWV / Wet-Delay:
23.8 / 31.4 GHz
23.8 /31.4 + 90 GHz
90 / 150 GHz
183.3 GHz , 4 chan.
Temp. Profiling (Trop.): 50-59 GHz Band (7 channels)
RPG-LWP
RPG-HATPRO
23.8 GHz
36.5/31.4 GHz
90 GHz
RPG-HUMPRO
RPG-TEMPRO
RPG-LWP-U90
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
HATPRO Instrument ConfigurationHATPRO Instrument Configuration
Scanningparaboloidmirror
ambienttemperaturetarget
beam combiner(wire grid) humidity profiler
temperature profiler
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
RPG-HATPRO Optical PerformanceRPG-HATPRO Optical Performance
23.8 GHz, HPBW = 3.9°, Sidelobes: <-30 dB 55.0 GHz, HPBW = 1.9°, Sidelobes: <-30 dB(6.5) (4.0)
humidity profiler temperature profiler
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
HATPRO Rain / Dew Protection SystemHATPRO Rain / Dew Protection System
removabledew blower
Prevent formation of dew and rain on microwave window by:
- strong blower system (150 Watts fan power 1.5 kW heater module)- Hydrophobic coating- Optional heater module (1.5 kWatts)System allows for humidity profiling during fog, rain
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
HATPRO Meteorological StationHATPRO Meteorological Station
Weather Station and Time Reference:
Rain Sensor: Provides rain flag for measurement documentation, control of super blower system
GPS-Clock: Provides time reference standard for synchronizationHumidity Sensor: Provides control of super blower system, documentationTemperature Sensor: Documentation of surface temperaturePressure Sensor: Documentation of baro-metric pressure, LN-target calibration
Humidity Sensor
Temp. Sensor Optional IR-Radiometer: Cloud base
height detection, ceilometer function
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
RPG-HATPRO Receiver LayoutRPG-HATPRO Receiver LayoutDual Profiler Direct Detection Filterbank Receivers based on MMIC Technology:
Antenna
Direct. Coupler
Pin Switch
Noise Diode
Noise Injection
LNA
WG-Splitter
DetBPF
T 0
ISO
LNA
50-60 GHz Band
22-32 GHz Band
new Dicke Switch design
analogMUX
16 BitADC
< 600 K System Noise Temperature
< 350 K System Noise Temperature
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
WG - Dicke Switch Performance (7.10.2006)Model Band (GHz) WG Trans. Loss (Off) I/O-Match On/Off Isol.
RPG-DS-112 X6.2 - 10.5 WR-112 < 0.2 dB < --25 dB > 32 dB
> 35 dB< --23 dB< 0.2 dBWR-90RPG-DS-90 K u10.5 - 16.0
RPG-DS-42 K18 - 26.5 WR-42 < 0.25 dB < --22 dB > 35 dB
RPG-DS-32 K - K a20.0 - 33.0 WR-32 < 0.3 dB < --20 dB > 35 dB
Speed
< 20 Hz
< 20 Hz
< 20 Hz
< 40 Hz
RPG-DS-28 K a26.5 - 40.0 WR-28 < 0.3 dB < --20 dB > 35 dB < 40 Hz
RPG-DS-15 V50.0 - 75.0 WR-15 < 0.35 dB < --18 dB > 35 dB < 40 Hz
RPG-DS-10 W75.0 - 110.0 WR-10 < 0.4 dB < --18 dB > 35 dB < 40 Hz
RPG-DS-6 D110.0 - 170.0 WR-6 < 0.5 dB < --16 dB > 35 dB < 40 Hz
RPG-DS-5 G170.0 - 220.0 WR-5 < 0.6 dB < --15 dB > 35 dB < 40 Hz
22.4 GHz WVL
183 GHz WVL
RPG Waveguide Dicke SwitchesRPG Waveguide Dicke Switches
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
RPG Waveguide Dicke SwitchesRPG Waveguide Dicke Switches
150 GHz Direct Detection Receiver
Wire Grid
Focussing Mirror
90 GHz Direct Detection Receiver
Dicke Switches
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
RPG-HATPRO Receiver Allan VarianceRPG-HATPRO Receiver Allan Variance
Allan Variance (53.86 GHz)
-1.75
-1.5
-1.25
-1
-0.75
-0.5
-0.25
0 0.5 1 1.5 2 2.5 3
log(time [sec])
log
(va
ria
nc
e)
Receivers obeyradiometer formula:
Bt
TTT sigsys
int
or:
)log(5.0)log( inttT Tested up to:tint = 1000 sec
30 sec. Integr. Time→ ∆T = 0.1 K
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Humidity Profiler Calibrations Humidity Profiler Calibrations
Automatic Calibrations:
- gain calibration continuously by periodic noise injection
- system noise calibration continuously by Dicke switch or
ambient target
- tip curve, only for humidity profiler
-Manual Calibrations:
- absolute calibration with liquid nitrogen (calibration of noise
standards)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Nonlinearity CalibrationNonlinearity Calibration
System gain nonlinearity is corrected by 4 point method:
Ud
T[K]Tn TnTsys Tc Th Th2
U1
U2
U3
U4
U5
Us
Detector model: 1,)( sigsysD TTGU
4 Equations result in:
G, Tsys, TN, a
Absolute Calibration:
Injection of additional noise TN from precision noise diode source
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Compact V-Band Receiver DesignCompact V-Band Receiver Design
Splitter and Filter Section
Boosters and Detectors
Video Amps,MUX, 16 Bit ADC
55 dB Pre-Amplifier
Noise InjectionCoupler
51-59 GHz 7 ChannelFilterbank Receiver
Corrugated Feedhorn
200 mm
70 mm
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Compact K-Band Receiver DesignCompact K-Band Receiver Design
280 mm85 mm
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Thermal Receiver StabilisationThermal Receiver Stabilisation
Two stage thermal stabilisation system:
Receiver stabilisation:
<30 mK over full opera-ting temperature range (-30°C to + 45°C)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Thermal Receiver StabilisationThermal Receiver Stabilisation
0.1 K
-30°C
+40°C
8 hours
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
How do Retrievals Work?How do Retrievals Work?
Radiosonde Data SetT(h), H(h), e.g. 10000samples
Brightness TemperaturesBT(f), f: water vapour line,oxygen line
Radiative
TransferCalculation
statistical methods:lin./quadr.regression,Neural Networks
Profiles T(h), H(h), derived from Microwave BTs
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
18580 high-resolution radio sondes18580 high-resolution radio sondes Rainy conditions included: RMS 0.45 kg/m^2Rainy conditions included: RMS 0.45 kg/m^2 Clear-sky RMS: 0.2 kg/m^2Clear-sky RMS: 0.2 kg/m^2
IWV RetrievalsIWV Retrievals
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
IWV Comparison with RadiosoundingsIWV Comparison with Radiosoundings
140 radio soundings (26. April to 4. July, Cabauw, KNMI)140 radio soundings (26. April to 4. July, Cabauw, KNMI) Radiosonds: Vaisala RS-92Radiosonds: Vaisala RS-92 No-Rain RMS: 0.43 kg/m^2, Bias: 0.05 kg/m^2No-Rain RMS: 0.43 kg/m^2, Bias: 0.05 kg/m^2 Two channel RPG-LWP: RMS: 0.6 kg/m^2, Bias similar to HATPROTwo channel RPG-LWP: RMS: 0.6 kg/m^2, Bias similar to HATPRO
HATPRORS
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Example of Rapid WV-FluctuationsExample of Rapid WV-Fluctuations
changes of up to 7 kg / m^2 within 1 hour!changes of up to 7 kg / m^2 within 1 hour!
Benin, West Africa, 9. April 2006 (AMMA)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
HATPRO Humidity Profiling up to 10 kmHATPRO Humidity Profiling up to 10 km
Benin, West Africa, 19. January 2006 (AMMA)
45 kg/m^2
27 kg/m^2
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Vertical humidity profiles (absolute humidity, 10 km)Vertical humidity profiles (absolute humidity, 10 km)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Vertical profiles (absolute humidity, 10km)Vertical profiles (absolute humidity, 10km)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
HATPRO Humidity ProfilingHATPRO Humidity Profiling
Comparison with radiosonde data. RMS Error : 1.0 g/m3 on the ground
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Example: Relative Humidity Profiles without T.-Profile InfoExample: Relative Humidity Profiles without T.-Profile Info
4 days time series (1740 profiles), H < 2000 m4 days time series (1740 profiles), H < 2000 m
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Example: Relative Humidity Profiles including T.-Profile InfoExample: Relative Humidity Profiles including T.-Profile Info
4 days time series (1740 profiles), H < 2000 m4 days time series (1740 profiles), H < 2000 m
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Example: Relative Humidity ProfilesExample: Relative Humidity Profiles
no temperature information addedno temperature information added
Temp. Inversion present
temperature information addedtemperature information added
Temp. Inversion present
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
LWP time seriesLWP time series
High temp. and spatial res. LWP time series for cloud analysis
temp. res.: 1 sec., abs. acc.: +/-20 g/m2 ,RMS Noise: +/- 2 g/m2
30 g/m2 (=0.03 mm)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Instrument InstallationsInstrument Installations
University of Salford, UK ARPAV, Weather Service of Veneto Italy Regione Marche Civil Protection Centre / Ancona, Italy KNMI, Dutch Weather Service, Cabauw Tokyo University / Japan University of Munich / Germany, Zugspitze Meteo Swiss / Switzerland, 3 Units AMMA Project, West Africa Aerospace Corporation / USA Institut für Meereskunde in Kiel / Germany, Research Ship „Polarstern“
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
183 GHz Water Vapour Radiometer183 GHz Water Vapour Radiometer
System Performance:
Frequencies:
183.3 +/- 1.4 GHz, BW: 0.8 GHz
183.3 +/- 3.6 GHz, BW: 1.0 GHz
183.3 +/- 7.0 GHz, BW: 2.0 GHz
183.3 +/- 14.0 GHz, BW: 2.0 GHz
System Noise Temperatures:
Channel 1: 1150 K
Channel 2: 1200 K
Channel 3: 1300 K
Channel 4: 1250 K
Sampling rate: 1 second
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
183 GHz WVR mounted in APEX 12 m Cassegrain183 GHz WVR mounted in APEX 12 m Cassegrain
Instrument operated by:
MPI for Radio Astronomy in Bonn
Site: Atacama desert SA (ALMA site)
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
183 GHz WVR Receiver Layout183 GHz WVR Receiver Layout
Antenna
Directional Coupler
Pin-Switch
Noise Diode
Noise Injection
Splitter
SubharmonicMixer IF-LNA
Local Oscillator (DRO) (30.55 GHz)
Detector + DC-AmpIF-Amp.IF-BPF
168-198 GHz
0.5-18 GHz
x3
IsolatorT 0
new Dicke Switch design
RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006
Summary of Important ResultsSummary of Important Results
• IWV accuracy of 7 channel retrieval including IWV accuracy of 7 channel retrieval including window channel at 31.4 GHz is in the order of window channel at 31.4 GHz is in the order of 0.45 kg/m^2 RMS0.45 kg/m^2 RMS
• IWV can be a rapidly changing parameter in IWV can be a rapidly changing parameter in particular close to the sea coast.particular close to the sea coast.
• 2 channel radiometer (23.8 and 31.4 GHz) 2 channel radiometer (23.8 and 31.4 GHz) provides slightly less accurate IWV retrieval of provides slightly less accurate IWV retrieval of 0.6 kg/m^2 RMS0.6 kg/m^2 RMS
• By including a Dicke switch to the receiver input By including a Dicke switch to the receiver input it is possible to achieve low BT noise of 10 mK it is possible to achieve low BT noise of 10 mK (1000 sec. integration time)(1000 sec. integration time)
Top Related