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Aerographers Mate, Module 03-Environmental Satellites and Weather Radar | Next
PROPERTIES OF ELECTROMAGNETIC WAVES |
CHAPTER 2
WEATHER RADAR
INTRODUCTION
Since the late 1940’s, radar has been used to track
weather systems. Subsequent advances were made in
radar transmitters, receivers, and other system
components. However, with the exception of transistor
technology, few changes were made to basic weather
radar systems through the 1970’s. In the late 1970's,
work began on the "next-generation” of weather radar
(NEXRAD) using Doppler technology. The use of
Doppler technology enabled weather radar systems to
not only detect meteorological targets with greater
detail, but also measure target motion and velocity. By
the mid 1980’s, a new weather radar that used this
technology was introduced. This system is known as
the weather surveillance radar-1988-Doppler, or
WSR-88D.
WSR-88D systems have been installed at several
Navy and Marine Corps shore-based weather stations.
Even if you do not have a WSR-88D at your command,
almost all weather radar information you will receive
is derived from Doppler radar. Thus, it is important
that you understand basic Doppler theory and the
WSR-88D system.
In this chapter we discuss the Doppler weather
radar (WSR-88D). We begin with a general explana-
tion of electromagnetic energy and radar propagation
theory followed by a discussion of Doppler radar
principles. We will then concentrate on the
configuration and operation of the WSR-88D system.
Finally, we complete the chapter with a discussion of
the advantages and limitations of WSR-88D products,
and the publications associated with the system.
ELECTROMAGNETIC ENERGY
LEARNING OBJECTIVES: Describe the
properties of electromagnetic energy. Define
electromagnetic wave, electromagnetic
spectrum, wavelength, amplitude, frequency,
and Rower.
Understanding
the fundamentals
of
electromagnetic (EM) energy will enhance your ability
to use weather radar. No matter how sophisticated the
radar system, theoretical limitations always exist. This
background knowledge will also help you to
understand the operation of the WSR-88D and to
effectively use the products it produces. In the
following text, we will begin with a general discussion
of electromagnetic energy followed by a description of
several properties related to electromagnetic waves.
ELECTROMAGNETIC WAVES
As discussed in chapter 1 of this module, all things
(whose temperature is above absolute zero) emit
radiation. Radiation is energy that travels in the form of
waves. If this energy were visible, it would appear as
sine waves, with a series of troughs and crests (fig.
2-1). Because radiation waves have electrical and
Figure 2-1.—Electromagnetic energy as sine waves.
2-1
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