Electromagnetic fields generated by a three dimensional global ocean circulation
- Resource Type
- Authors
- Lawrence A. Mysak; Robert H. Tyler; Josef M. Oberhuber
- Source
- Journal of Geophysical Research: Oceans. 102:5531-5551
- Subject
- Electromagnetic field
Atmospheric Science
Ecology
Meteorology
Ocean current
Paleontology
Soil Science
Forestry
Mechanics
Aquatic Science
Oceanography
Magnetic field
Waves and shallow water
Geophysics
Space and Planetary Science
Geochemistry and Petrology
Electric field
Stream function
Earth and Planetary Sciences (miscellaneous)
Electric current
Induction equation
Physics::Atmospheric and Oceanic Physics
Geology
Earth-Surface Processes
Water Science and Technology
- Language
- ISSN
- 0148-0227
A simplified form of the motional induction equation is used to calculate the dominant three-dimensional (3-D) electromagnetic (EM) fields generated by a specified steady 3-D global ocean circulation. The EM calculations require, at most, vertical integrations and do not require running a global 3-D model. Two cases for ocean bottom conductivity are considered: an electrically insulating ocean bottom and a high-conductance sediment layer. The approximations are discussed, and the solutions are plotted for various depth levels. Many aspects of the dominant ocean-generated EM fields (particularly the electric currents near the sea surface and the magnetic fields) are shown to be insensitive to ocean bottom conductivity. Other aspects (particularly the horizontal electric field in shallow water) are very sensitive. We perform a global integration to estimate the role of the “nonlocal” electric currents. We find that the importance in including these nonlocal currents when making EM field estimates is the same or less than that for including a model for the bottom conductance. Hence the simple EM estimates from one-dimensional integrations are not improved in globally integrated models until these models include a realistic model for bottom conductivity.