1. Boundary layer temperature profile observations using ground-based microwave radiometers Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen AMMA - Benin UFS Schneefernerhaus LMU München Bernhard Pospichal Susanne Crewell, Ulrich Löhnert, Thomas Rose

2. HATPRO microwave profiler Dew blower Radome with hydrophobic coating GPS clock Rain sensor Instrumentation/Theory Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

3. What does HATPRO measure?  Continuous measurements of thermal emission by atmospheric components at 14 frequencies (see below) expressed as brightness temperatures. A: 22.235 –31.4 GHz, 7 channels at the water vapor line and the atmospheric window B: 51.26 – 58.0 GHz, 7 frequencies at the oxygen absorption line Instrumentation/Theory Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

4.  Distinct microwave absorption characteristics of H 2 O and O 2 between 1 and 200 GHz  Clouds are semi-transparent  observations of cloud properties as well as temperature and humidity profiles possible  Higher absorption of clouds at higher frequencies Microwave spectrum Instrumentation/Theory Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

5. HATPRO: two different operation modes vertical measurements High temporal resolution (1 sec) Simultaneous observation of all 14 channels Zenith observations Products: Retrieval of LWP (liquid water path) and IWV (integrated water vapor) Temperature profiles up to 10 km altitude Humidity profiles up to 5 km Retrievals: Statistical retrieval algorithms are developed on the basis of a large set of atmospheric profiles observed by radiosondes Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

6. Zenith Observations Time series of IWV (Integrated water vapor) and LWP (Cloud liquid water path) Theoretical accuracy: <1 kg m -2 for IWV ~20 g m -2 for LWP Observations from 26 Oct – 1 Nov 2005 in Lindenberg (IWV top, LWP bottom) Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

7.  high receiver stability  low noise level  scans between 5° - 90°  small antenna beam (2° HPBW)  simple regression algorithms Boundary layer temperature observations At prescribed intervals (for example 20 min) boundary layer scans can be performed. Assuming horizontal homogeneity the temperature profile can be determined with high vertical resolution Boundary layer scans vertical resolution (< 1km height) ~8m@10m to ~300m@400m Boundary layer temperature profile measurements using ground-based microwave radiometers

8. Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Performance/Accuracy Accuracy of boundary layer scan retrievals Up to 1400 m above ground, the results can be improved significantly by performing boundary layer scans. Even with a higher noise level angular information provides improved temperature profile Boundary layer temperature profile measurements using ground-based microwave radiometers 1400m

9. 112 m asl 72 m asl 98 80 60 40 20 10 Falkenberg Tower:10 min integration time Lindenberg RS92 launched 4 times a day 4 km Falkenberg HATPRO: 6 angles each 30 s integration time every 20 min Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Launch campaign – Comparison setup Boundary layer temperature profile measurements using ground-based microwave radiometers

10. Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Launch campaign – Falkenberg area Boundary layer temperature profile measurements using ground-based microwave radiometers

11. Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Comparison zenith observations/boundary layer scans Boundary layer temperature profile measurements using ground-based microwave radiometers blue: retrieval from HATPRO, red: Radiosounding Lindenberg 10 km 2 km

12. Comparison with Radiosondes Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers Solid line: Hatpro profile Dashed line: Radiosonde measurements

13. dry adiabatic lapse rate T tower / °C All weather conditions Comparison with tower Boundary layer temperature profile measurements using ground-based microwave radiometers Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen

14. N=48  RMS between RS & HATPRO lower than 1 K below 1 km  slightly depends on wind direction  lower inversion strength is well detected  6 angle retrieval performs much better than 5 Bias RMS Comparison with tower and RS Boundary layer temperature profile measurements using ground-based microwave radiometers

15. Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen AMMA AMMA (African Monsoon Multidisciplinary Analysis) HATPRO measurements in Benin since January 2006 Goals: better understanding of processes in tropical boundary layer boundary layer height temperature profiles in connection with dry and moist air masses humidity variations cloud liquid water statistics Additional instruments: Lidar Ceilometer, Micro Rain Radar, Temperature and wind measurements, X-Band-Radar, VHF profiler, UHF profiler, Radiosounding network Boundary layer temperature profile measurements using ground-based microwave radiometers

16. AMMA - African Monsoon Multidisciplinary Analysis Case study 10/11 April 2006, Nangatchori Benin Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers Strong temperature inversion Temperature bias HATPRO Temperature (°C)

17. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers IWV (water vapor content) time series

18. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

19. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

20. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

21. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

22. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

23. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

24. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

25. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

26. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers

27. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Boundary layer temperature profile measurements using ground-based microwave radiometers Lidar ceilometer (Vaisala CT25K), 4 April 2006

28. AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Wind direction Boundary layer temperature profile measurements using ground-based microwave radiometers Features: Distinct jumps in wind direction to south at midnight (often observed) Advection of moister and more stable air masses Shallow temperature inversion is eroded Explanation – gravity current moving north evoked by sea breeze at the coast around sunset (some questions remain due to sparse data) No clouds during whole event! 10 April 2006 11 April 2006

29. Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen Impressions from Nangatchori Boundary layer temperature profile measurements using ground-based microwave radiometers

30. What to do next?....  Ground-based microwave radiometers can provide valuable information of temperature and humidity profiles in very different climate conditions during clear and cloudy conditions with good accuracy  Angular scans improve the performance of the lowest 1.5 km significantly  Future: Exploit synergy with other remote sensing systems (temperature lidar, wind profiler, sodar, etc.) for more complete description of the atmospheric state Conclusions and outlook Boundary layer temperature profile measurements using ground-based microwave radiometers Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen 300 K 290 K

31. Thank you for your attention! AMMA - African Monsoon Multidisciplinary Analysis Bernhard Pospichal, ISARS 2006 Garmisch-Partenkirchen