Mean flow
Encyclopedia
In fluid dynamics
, the fluid
flow is often decomposed into a mean flow – and deviation
s from the mean
. The averaging can be done either in space or in time.
In the atmospheric sciences
, the mean flow is taken to be the purely zonal flow
of the atmosphere which is driven by the temperature contrast between equator
and the poles.
For example: given two discharge
s (Q) 3 m³/s and 5 m³/s. We can use these flow rates Q to calculate the mean flow rate Qmean. Which in this case is Qmean = 4 m³/s.
Fluid dynamics
In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
, the fluid
Fluid
In physics, a fluid is a substance that continually deforms under an applied shear stress. Fluids are a subset of the phases of matter and include liquids, gases, plasmas and, to some extent, plastic solids....
flow is often decomposed into a mean flow – and deviation
Deviation (statistics)
In mathematics and statistics, deviation is a measure of difference for interval and ratio variables between the observed value and the mean. The sign of deviation , reports the direction of that difference...
s from the mean
Mean
In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....
. The averaging can be done either in space or in time.
In the atmospheric sciences
Atmospheric sciences
Atmospheric sciences is an umbrella term for the study of the atmosphere, its processes, the effects other systems have on the atmosphere, and the effects of the atmosphere on these other systems. Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather...
, the mean flow is taken to be the purely zonal flow
Zonal flow
Zonal flow is a meteorological term meaning that the general flow pattern is west to east, or east to west, along the Earth's latitude lines . Extratropical cyclones in this environment tend to be weaker, moving faster and producing relatively little impact on local weather.-References:**...
of the atmosphere which is driven by the temperature contrast between equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
and the poles.
Example
Calculation of the mean flow may often be as simple as the mathematical mean: simply add up the given flow rates and then divide the final figure by the number of initial readings.For example: given two discharge
Discharge
Discharge in the context to expel or to "let go" may refer to:* A military discharge, issued when a member of the armed forces is released from service* Termination of employment, the end of an employee's duration with an employer...
s (Q) 3 m³/s and 5 m³/s. We can use these flow rates Q to calculate the mean flow rate Qmean. Which in this case is Qmean = 4 m³/s.