1. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Performance of water vapor radiometers at 22 and 183 GHz developed at RPG Thomas Rose, Harald Czekala (Radiometer Physics GmbH)

2. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Microwave Bands Frequencies : 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

3. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 HATPRO Instrument Configuration

4. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 RPG-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

5. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 HATPRO Rain / Dew Protection System removable dew 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

6. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 HATPRO 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 synchronization Humidity Sensor: Provides control of super blower system, documentation Temperature Sensor: Documentation of surface temperature Pressure Sensor: Documentation of baro-metric pressure, LN-target calibration Humidity Sensor Temp. Sensor Optional IR-Radiometer: Cloud base height detection, ceilometer function

7. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 RPG-HATPRO Receiver Layout Dual Profiler Direct Detection Filterbank Receivers based on MMIC Technology:

8. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 RPG Waveguide Dicke Switches

9. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 RPG Waveguide Dicke Switches 150 GHz Direct Detection Receiver Wire Grid Focussing Mirror 90 GHz Direct Detection Receiver Dicke Switches

10. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 RPG-HATPRO Receiver Allan Variance Receivers obey radiometer formula: or: Tested up to: t int = 1000 sec 30 sec. Integr. Time → ∆T = 0.1 K

11. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 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)

12. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Nonlinearity Calibration System gain nonlinearity is corrected by 4 point method: Detector model: 4 Equations result in: G, Tsys, T N, a Absolute Calibration: Injection of additional noise T N from precision noise diode source

13. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Compact V-Band Receiver Design Splitter and Filter Section Boosters and Detectors Video Amps, MUX, 16 Bit ADC 55 dB Pre-Amplifier Noise Injection Coupler 51-59 GHz 7 Channel Filterbank Receiver Corrugated Feedhorn 200 mm 70 mm

14. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Compact K-Band Receiver Design 280 mm 85 mm

15. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Thermal Receiver Stabilisation Two stage thermal stabilisation system: Receiver stabilisation: <30 mK over full opera- ting temperature range (-30°C to + 45°C)

16. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Thermal Receiver Stabilisation 0.1 K -30°C +40°C 8 hours

17. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 How do Retrievals Work?

18. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006  18580 high-resolution radio sondes  Rainy conditions included: RMS 0.45 kg/m^2  Clear-sky RMS: 0.2 kg/m^2 IWV Retrievals

19. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 IWV Comparison with Radiosoundings  140 radio soundings (26. April to 4. July, Cabauw, KNMI)  Radiosonds: Vaisala RS-92  No-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 HATPRO HATPRO RS

20. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Example of Rapid WV-Fluctuations changes of up to 7 kg / m^2 within 1 hour! Benin, West Africa, 9. April 2006 (AMMA)

21. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 HATPRO Humidity Profiling up to 10 km Benin, West Africa, 19. January 2006 (AMMA) 45 kg/m^2 27 kg/m^2

22. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Vertical humidity profiles (absolute humidity, 10 km)

23. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Vertical profiles (absolute humidity, 10km)

24. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 HATPRO Humidity Profiling Comparison with radiosonde data. RMS Error : 1.0 g/m 3 on the ground

25. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Example: Relative Humidity Profiles without T.-Profile Info 4 days time series (1740 profiles), H < 2000 m

26. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Example: Relative Humidity Profiles including T.-Profile Info 4 days time series (1740 profiles), H < 2000 m

27. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Example: Relative Humidity Profiles no temperature information added Temp. Inversion present temperature information added Temp. Inversion present

28. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 LWP time series High temp. and spatial res. LWP time series for cloud analysis temp. res.: 1 sec., abs. acc.: +/-20 g/m 2,RMS Noise: +/- 2 g/m 2 30 g/m 2 (=0.03 mm)

29. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Instrument 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“

30. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 183 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

31. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 183 GHz WVR mounted in APEX 12 m Cassegrain Instrument operated by: MPI for Radio Astronomy in Bonn Site: Atacama desert SA (ALMA site)

32. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 183 GHz WVR Receiver Layout

33. RPG Radiometer Physics GmbH WVR Workshop – Wettzell, 9. Oct. 2006 Summary of Important Results IWV accuracy of 7 channel retrieval including window channel at 31.4 GHz is in the order of 0.45 kg/m^2 RMSIWV accuracy of 7 channel retrieval including window channel at 31.4 GHz is in the order of 0.45 kg/m^2 RMS IWV can be a rapidly changing parameter in particular close to the sea coast.IWV can be a rapidly changing parameter in particular close to the sea coast. 2 channel radiometer (23.8 and 31.4 GHz) provides slightly less accurate IWV retrieval of 0.6 kg/m^2 RMS2 channel radiometer (23.8 and 31.4 GHz) provides slightly less accurate IWV retrieval of 0.6 kg/m^2 RMS By including a Dicke switch to the receiver input it is possible to achieve low BT noise of 10 mK (1000 sec. integration time)By including a Dicke switch to the receiver input it is possible to achieve low BT noise of 10 mK (1000 sec. integration time)