# one minute rain rate value

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#### nafah

##### Member level 3
Hi,
What's the manning of one minute rain rate value, this value is required in rain attenuation prediction.?

And how I can convert the average rain rate in (mm) to one minute rain rate (mm/h)?

Thanks for all

#### vfone

Yes, the rain rate is required in microwaves propagation, because rain can induce phase shift, attenuation, and depolarization.

Perhaps if you know that an hour has 60 minutes, its not very hard to calculate mm/h if you have mm/min value.

#### jiripolivka

Yes, the rain rate is required in microwaves propagation, because rain can induce phase shift, attenuation, and depolarization.

Perhaps if you know that an hour has 60 minutes, its not very hard to calculate mm/h if you have mm/min value.

Rain rate calculations are presented in meteorological books and manuals.
For applications in microwave propagation, real calculations are quite difficult due to the following:
- accumulated precipitation water is measured by rain gauges of different designs. Trying to use time derivatives never works, and "our water (causing additional loss)" never falls into a particular rain gauge.
- trying to use radar is very uncertain as rain rate causing certain reflectivity is an exponent in an uncertain Z function.
- The only real way to obtain loss over time must be measured over one year to get good statistical distribution. FRom this distribution curve one can estimate short-time rain effect.
- Real precipitations are very local; rain cells vary in size and form, terrain takes part as well as wind.

To conclude: rain rate is difficult to obtain, mostly for shorter time intervals. Using it to get microwave loss makes not much sense. Best is to use a radio link for long-time observation, then estimate short-time effects if needed.

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