CHAPTER 2WEATHER RADARINTRODUCTIONSince the late 1940’s, radar has been used to trackweather systems. Subsequent advances were made inradar transmitters, receivers, and other systemcomponents. However, with the exception of transistortechnology, few changes were made to basic weatherradar systems through the 1970’s. In the late 1970's,work began on the "next-generation” of weather radar(NEXRAD) using Dopplertechnology. The use ofDoppler technology enabled weather radar systems tonot only detect meteorological targets with greaterdetail, but also measure target motion and velocity. Bythe mid 1980’s, a new weather radar that used thistechnology was introduced. This system is known asthe weather surveillance radar-1988-Doppler, orWSR-88D.WSR-88D systems have been installed at severalNavy 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 receiveis derived from Doppler radar. Thus, it is importantthat you understand basic Doppler theory and theWSR-88D system.In this chapter we discuss the Doppler weatherradar (WSR-88D). We begin with a general explana-tion of electromagnetic energy and radar propagationtheory followed by a discussion of Doppler radarprinciples. We will then concentrate on theconfiguration and operation of the WSR-88D system.Finally, we complete the chapter with a discussion ofthe advantages and limitations of WSR-88D products,and the publications associated with the system.ELECTROMAGNETIC ENERGYLEARNING OBJECTIVES: Describe theproperties of electromagnetic energy. Defineelectromagnetic wave, electromagneticspectrum, wavelength, amplitude, frequency,and Rower.Understandingthe fundamentalsofelectromagnetic (EM) energy will enhance your abilityto use weather radar. No matter how sophisticated theradar system, theoretical limitations always exist. Thisbackground knowledge will also help you tounderstand the operation of the WSR-88D and toeffectively use the products it produces. In thefollowing text, we will begin with a general discussionof electromagnetic energy followed by a description ofseveral properties related to electromagnetic waves.ELECTROMAGNETIC WAVESAs discussed in chapter 1 of this module, all things(whose temperature is above absolute zero) emitradiation. Radiation is energy that travels in the form ofwaves. If this energy were visible, it would appear assine waves, with a series of troughs and crests (fig.2-1). Because radiation waves have electrical andFigure 2-1.—Electromagnetic energy as sine waves.2-1
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business