WMOD00399

• Title: WMO Training Workshop on Weather Modification for Meteorologists - Lecture Notes
• Date: 12/1/1979
• Weather Modification - Doc Type: Report

APPLICATION OF METEOROLOGICAL RADARS TO WEATHER MODIFICATION

Ju. V. Melnichuk

Central Aeorological Observatory
Moscow Region, USSR

1.

INTRODUCTION

1.1 The use of radar in meteorology has prompted new research into cloud
physics and precipitation and the development of methods for rainfall stimulation as
well as the solution of practical prclblems concerning storm warnings, hail detection
and short-range weather forecasting. The first obvious applications of radar are the
remote detection and monitoring of cloud zones and precipitation, determination of
their geometric characteristics (horizontal dimensions and configurations, upper and,
in the absence of precipitation, lower boundaries of cloud radar echoes), and the
obtaining of the radar reflectivity distribution in individual clouds or cloud systems.
All these applications have proved extremely useful both in research and in operational
work. The selection and effectiveness of any particular rainfall stimulation method
in a given region depends on the physical characteristics of the supercooled clouds
which are most frequently found in that region. Clearly, a study of cloud types,
spatial extent, degree of homogeneity and frequency of occurrence is highly important
in the preparation of any weather modification experiment. Regular radar observations
of the characteristics of cloud and precipitation radar echo distribution are one of
the main sources of such information. The method for obtaining them varies widely,
from using observations and recording the I:adar echo on the simplest plan position
indicator (PPI) or range-height indicator (RHI) in conical or vertical sections of the
radar's scanning zone, to recording the radar echo distribution in digital form in the
whole upper hemisphere of the scanning zone, with programmed antennae scanning, and
subsequent computer precessing of this infclrmation. The data obtained in this way are
used for both preliminary studies of cloud characteristics in the selected region and
the planning and conduct of the cloud-seeding experiment itself. The method used for
analyzing the observations is virtually the same as that widely used for storm warnings
over the last few decades by many national Meteorological Services, and does not need
to be discussed further.

1.2 The purpose of this paper is to briefly survey the new radar techniques
for studying clouds and precipitation which can be used in projects aimed at the
modification of precipitation processes, in specific clouds, in order to stimulate
additional rainfall. The theory behind radar methods will be considered only to the
extent that it furthers the understanding of their physical bases and the possibilities
of using them for specific measurements.