Samples of analyses

Rainrate vs. time, Event on June 18, 1997
Figure 11: Event on June 18, 1997, 17:00 - 19:00 in Graz / Austria

DSD for the most intense period of this event
Figure 12: DSD for the most intense period of this event. MP-DSD (yellow), JD-DSD (green) and JT-DSD (red) indicated.

The DSD for the most intense period of this event (6 minutes - from 17:54 till 18:00) is given in the above figure, clearly indicating drops of more than 7 mm in equivolmetric sphere diameter. This is a very important result, since many distrometers used so far stop classifying drops at 5.5 mm equivolumetric sphere diameter. That makes a great difference in practically all DSD dependent applications (weather radar and wave propagation, soil erosion studies etc.).

Raindrop with equ. sph. diameter = 6.12 mm
Figure 13a: Raindrop measured at 17:55:32.996, equ. sph. diameter = 6.12 mm, precise correction method applied.

Raintdrop with equ. sph. diameter = 7.52 mm
Figure 13b: Raindrop measured at 17:55:07.013, equ. sph. diameter = 7.52 mm, precise correction method applied.

Horizontal copolar radar reflectivity ZH
Figure 14: Horizontal copolar radar reflectivity ZH derived from the rainrate only (black line) and from the full DSD info obtained by the distrometer. The black line represents an approximation formula, closely related to the Marshall-Palmer [1948] DSD (yellow line in the following picture for 6 minutes period). Parameters: elevation angle = 0°, temperature = 10°C, drop shape = ROPEX.

Whenever the red line exceeds the black one, this usually indicates that there are more 'big' drops than proposed by Marshall-Palmer (MP-DSD). It is clearly seen that considerable deviations occur, as also stated by Figure 12. Our measurements from all around the world indicate that the behaviour of DSDs is climate dependent.

DSD for a twenty minutes period of tropical rai
Figure 15: DSD for a twenty minutes period of tropical rain (measured in Lae/Papua New Guinea), class width = 0.1 mm, uncalibrated data below 0.6 mm. Rainrate = 25.24 mm/hr. Exponential DSDs: N0 = 8000 (yellow), 1400 (red), 30000 (green) /m3mm.

Front view to be corrected for distortion due to horizontal motion
Figure 16a: Front view to be corrected for distortion due to horizontal motion.

Front view corrected by approximation method
Figure 16b: Front view corrected by approximation method.

Front view corrected by precise method
Figure 16c: Front view corrected by precise method, canting angle = 18.8°.

Further samples of canted raindrops:

Figure 17a
Figure 17a

Figure 17b
Figure 17b

Figure 17cFigure 17c

Figure 17dFigure 17d

Figure 17eFigure 17e

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