wq (version 0.4.3)

phenoAmp: Phenological amplitude

Description

Finds various measures of the amplitude of the annual cycle, or of some specified month range.

Usage

## S3 method for class 'ts':
phenoAmp(x, mon.range = c(1, 12))
## S3 method for class 'zoo':
phenoAmp(x, mon.range = c(1, 12))

Value

A data frame.

Rdversion

1.1

Details

phenoAmp gives three measures of the amplitude of a seasonal cycle: the range, the range divided by the mean, and the standard deviation divided by the mean, i.e., the coefficient of variation.

These measures can be restricted to a subset of the year by giving the desired range of month numbers. This can be useful for isolating measures of, say, the spring and autumn phytoplankton blooms in temperate waters. In the case of a monthly time series, a non-missing value is required for every month or the result will be NA, so using a period shorter than one year can also help avoid any months that are typically not covered by the sampling program. Similarly, in the case of dated observations, a shorter period can help avoid times of sparse data.

tsMake can be used to produce "ts" and "zoo" objects suitable as arguments to this function.

References

Cloern, J.E. and Jassby, A.D. (2008) Complex seasonal patterns of primary producers at the land-sea interface. Ecology Letters 11, 1294--1303.

See Also

phenoPhase, tsMake

Examples

y <- sfbayChla[, 's27']

p2 <- phenoAmp(y)
p2
apply(p2, 2, mean, na.rm=TRUE)

phenoAmp(y, c(1, 6))