Subject: Re: Definition of "Dbz"
From: mikemc@unicorn.ultranet.com (Mike McCann)
Date: Wed, 13 Sep 1995 10:53:22
Message-ID: <mikemc.16.000AE40E@unicorn.ultranet.com>

In article <434uhr$j2@vixen.cso.uiuc.edu> AISS Staff <network@aiss.uiuc.edu>
writes:
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>From: AISS Staff <network@aiss.uiuc.edu>
>Newsgroups: sci.geo.meteorology
>Subject: Definition of "Dbz"
>Date: 12 Sep 1995 21:36:59 GMT
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>In another unrelated newsgroup in a discussion about weather radar the 
>unit "Dbz" was mentioned as a measure of precipitation intensity.  What 
>is the definition of a "Dbz"?  Thanks.

Hi:

I'm not a weather radar expert but thought I'd take a crack at this.
I'd be glad to be corrected if I've gone astray anywhere.

Anyway...there is a relationship between radar reflectivity and rainfall 
rate. This  relationship is variable depending upon the type of storm.

(Consider for example a slightly far-fetched case of a thunderstorm with
strong convective up-drafts. The thing may contain lots of rain (or hail) but
not much is falling because the updrafts are either slowing its rate of
descent
or possibly making some of it go up. There are lots of strong radar echoes
but 
the amount of precip hitting the ground is low compared to other 
storms without the strong updraft. There are lots of other reasons 
why the relationship would vary but I'm even less qualified to 
explain them.)

Anyway, the WSR-88D radar I believe uses a fixed relationship 
between Z and rainfall rate. That is 

Z=300(R)**1.4
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*   Mike McCann                        Remember, if you don't like      *
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