NCEP.Tailwind: Calculate flow-assistance according to equation 'Tailwind'

In RNCEP: Obtain, Organize, and Visualize NCEP Weather Data

Description

This function calculates flow-assistance according to equation Tailwind and determines the speed of forward and sideways movement if an animal behaves according to the rules of equation Tailwind.

Usage

NCEP.Tailwind(u, v, direction, airspeed=NA,...)

Arguments

u	A numeric value indicating the U (i.e. zonal or east/west) flow component in meters per second, toward east being positive. Values must describe the direction into which the flow is moving.
v	A numeric value indicating the V (i.e. meridional or north/south) flow component in meters per second, toward north being positive. Values must describe the direction into which the flow is moving.
direction	A numeric value indicating the preferred direction of movement in degrees from North.
airspeed	The animal's speed relative to the flow in meters per second. This value does not affect the calculation of flow-assistance, but does affect the animal's forward and sideways movement.
...	Any extra arguments passed to the flow-assistance equation.

Details

This function calculates flow-assistance and forward and sideways movement according to equation Tailwind. Equation Tailwind considers flow-assistance to be the component of the flow moving parallel to the specified direction, with negative values indicating flows against the specified direction.

Value

A data.frame containing flow-assistance (‘fa’), the animal's forward speed (‘forward.move’ which includes the animal's own airspeed), the animal's sideways speed (‘side.move’ which includes the animal's own airspeed), the component of the flow parallel to preferred direction of movement(‘tailwind’), the component of the flow perpendicular to the preferred direction of movement (‘sidewind’), the animal's speed relative to the flow (‘airspeed’), and the animal's speed relative to the fixed Earth (‘groundspeed’) each in meters per second, presuming u, v, and airspeed were given in meters per second.

Author(s)

Michael U. Kemp [e-mail]

References

To cite package 'RNCEP' in publications use:

Kemp, M. U., van Loon, E. E., Shamoun-Baranes, J., and Bouten, W. 2011. RNCEP:global weather and climate data at your fingertips. – Methods in Ecology and Evolution. DOI:10.1111/j.2041-210X.2011.00138.x.

For more information on flow-assistance and equation Tailwind see:

Kemp, M.U., Shamoun-Baranes, J., van Loon, E. E., and Bouten, W. 2012. Quantifying flow-assistance and implications for movement research. – Journal of Theoretical Biology. In prep.

Examples

library(RNCEP)
## Using NCEP.Tailwind to calculate flow-assistance ##
tst <- NCEP.Tailwind(u=-2, v=-1, direction=225, airspeed=12)

RNCEP documentation built on July 1, 2020, 7:10 p.m.