WMOD00296 ‎(2)‎

• Contract/Permit #: 14-06-D-5640
• Title: Park Range Atmospheric Water Resources Program Final Report
• Date: 9/30/1969
• Weather Modification - Doc Type: Report

...

where

M2 - 1
K=---
M2 + 2

( 4)

..

and m is the refractive index of the scatters. The factor 10-12 is used so
that Z and N may be expressed in their conventional units of mm6/m3 and
cm -1, respectively.

Substituting the quantities for N and V into equation 1 we have:

512 P >..2 R2 1012
r t
---

Pt G2 1T3 e \~ h K2

(5)

z =

The estimate for snowfall intensity may then be obtained from the relation-
ship:

z

C IC2
1

(6)

where C1 and C2 are empirical constants and I is in mm/hr.

Radar calibration procedures that were used to determine appropriate values
of the radar constants are described in Appendix B.

..

2. 5. 2 Method of Obtaining Data

In the Park Range program, rather than using photographs to estimate pre-
cipitation intensity, the AGC voltage was used, as described by Handman
and Davis (1964). The Automatic Gain Control (AGC) voltage is related to
the power received by the radar. Essentially, the AGC circuit is a sample -
hold circuit in which the gain of the receiver is adjusted to a certain value
dependent upon the amount of signal sampled in the range gate. In practice
the amount of signal in the range gate (.25 micro sec. ) adjusts the receiver
gain until the arrival of another range gate.

In the Park Range program a dual channel recorder was used to record the
AGC voltage and slant range. In practice vertical profiles or slices were
taken along selected azimuths as follows:

(1) A particular azimuth was selected, generally dependent on the
wind direction.

(2) The antenna was pointed in the vertical direction and an aided

'C

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