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

Fig.7a - Time period: 6:05:00 - 7:15:52
Fig.7b - Time period: 7:15:53- 6:26:47
HP60
Fig.7c - Time period: 6:26:48 - 9:37:42
Fig.7d - Time period: 9:37:42 - 10:48:37
Fig.7e - Time period: 10:48:38- 11:59:31
Fig.7f - Time period: 11:59:32- 13:15:56
Fig.7g - Time period: 13:15:57- 14:26:50
Fig.7h - Time period: 14:26:51- 15:37:47
Fig.7i - Time period: 15:37:45 - 16:48:38
Fig.7j - Time period: 16:48:39 - 17:59:32
    Fig. 7a-j Noise temperature of the atmosphere measured 8/11/1997 between 6.05 and 17.59 local time in the location CTU Prague - Dejvice (frequency: 11.25GHz, elevation 30°) - Rain phenomena.
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



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Last change: February 4, 1997