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Publicado el: 2017-09-21
Tiempo de estudio aproximado: .75 - 1.00 h
Incluye sonido: no
Áreas temáticas
Geospatial
Descripción:
Gravity is an important part of geodesy, with implications for height measurements and many other applications. In this module, we explore the concept of equipotential surfaces and relate them to gravity. Then we discuss geodetic applications that rely on accurate gravity measurements, including leveling surveys and floodplain mapping. We introduce a special surface based on gravity, called the gravimetric geoid, and explain why we want to use it as a reference datum. We discuss how to measure Earth’s gravity and introduce you to the National Geodetic Survey’s GRAV-D project, including how and why the U.S. and a number of other countries plan to use a gravity-based vertical datum.
Objetivos:
After completing the lesson, a learner will be able to do the following:
- Define gravitational potential energy.
- Define an equipotential (level) surface.
- Describe how level surfaces aren’t parallel and their spacing changes.
- Explain the impact of gravity variations in determining flood plains.
- Explain how orthometric correction is applied to leveling measurements.
- Explain methods for measuring gravity.
- Define the geoid and its relationship to gravity and sea level.
- Explain why models of the geoid are necessary.
- Give examples of places where airborne gravity can collect better data than other gravity methods.
- Explain the goals of GRAV-D program.
- Explain that the gravity field varies over time.
Palabras clave
gravity, geodesy, geoid, gravitational, gravitational potential energy, equipotential surface, GRAV-D, vertical datum, gravitational datum, gravimetric datum, leveling, deflection of vertical, GRACE, GOCE, satellite, gravimeter