RADIOMETRIC MEASUREMENT OF THE RAIN PHENOMENA M. Hajný, S. Gerrits CTU, Faculty of Electrical Eng., Dept. of Electromagnetic Field, Technická 2, 166 27 Praha 6, e-mail: hajny@ufa.cas.cz
1.Why noise measurement 2. Structure of experiment 3. Calibration of radiometer 4. Noise temperature of atmosphere 5. Attenuation 6. Examples of calculations 7. Conclusion 8. Acknowledgement 9. References
1.Why noise measurement + sensitivity simple configuration, mobility easy to change configuration of experiment interesting from systems point of view basic data for computer simulation of interaction Microwaves in the rain Area - values of attenuation (generally - rain, snow, clouds, hail) - low temperature calibration (is necessary to do very exactly) stability of radiometer meteorological data large volume of data Fig. 1 Structure of the radiometric experiment
3. Calibration of radiometer A. - hot calibration (20 to 100°C) B. - low temperature calibration ice : (-5 to 20°C) liquid Nitrogen: (-197 to 0°C)
4. Noise temperature of the atmosphere
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Fig.8a - Time period: 6:30:00- 7:40:50 |
Fig.8b - Time period: 7:40:51- 8:51:41 |
Fig. 8a,b Noise temperature of the atmosphere measured 9/11/1997 between 6.30 and 7.40 local time. (frequency: 11.25GHz, elevation 30°, site: Prague-Dejvice) - Clear conditions. |
5.Attenuation
6.Examples:
7. Conclusion
- the radiometry is a useful tool for research structure of troposphere
- measurement give the support for models of propagation in the rain (snow) area.
- knowledge of serious meteorological data are necessary for this measurements
8. Acknowledgements
This work and research has been conducted at the Department of Electromagnetic Field CTU in Prague and has been supported by Grant CTU 30/97/457 and the results are used as support for works on the COST 255 project.
9. References
[1] MAZANEK, M.: Radiometricka mereni v druzicovych spojich. Kandidatska disertacni prace, CVUT FEL Praha, rijen 1979
[2] GERRITS, S.: Radiometric measurement of the atmosphere, bachelor thesis, CTU FEE Prague, May 1997
[3] BRUSSAARD, G.: Radiometry; A useful prediction tool?, Noordwijk, ESA Scientific and Technical Publications Branch, 1985, (ESA SP-1071)
[4] HAJNÝ, M. - BAZANT, L.: Scattering Function and Attenuation of Raindrops, Radioelektronika 97, STU Bratislava, April 1997
[5] HAJNY, M. - MAZANEK, M. - FISER, O.: Computation of Raindrops Scattering, 2nd Management Committee Meeting COST 255, Trest, May 1997
[6] HAJNY, M. - MAZANEK, M.: Calculation of the Rain Specific Attenuation, Rain Specific Path Delay, XPD and XPI, 3rd Management Committee Meeting COST 255, Brussels, October 1997
Last change: February 4, 1997