filter.growing.season: GPP-based Growing Season Filter

In bigleaf: Physical and Physiological Ecosystem Properties from Eddy Covariance Data

GPP-based Growing Season Filter

Description

Filters annual time series for growing season based on smoothed daily GPP data.

Usage

filter.growing.season(GPPd, tGPP, ws = 15, min.int = 5)

Arguments

GPPd	daily GPP (any unit)
tGPP	GPP threshold (fraction of 95th percentile of the GPP time series). Takes values between 0 and 1.
ws	window size used for GPP time series smoothing
min.int	minimum time interval in days for a given state of growing season

Details

The basic idea behind the growing season filter is that vegetation is considered to be active when its carbon uptake (GPP) is above a specified threshold, which is defined relative to the peak GPP (95th percentile) observed in the year. The GPP-threshold is calculated as:

GPP_threshold = quantile(GPPd,0.95)*tGPP

GPPd time series are smoothed with a moving average to avoid fluctuations in the delineation of the growing season. The window size defaults to 15 days, but depending on the ecosystem, other values can be appropriate.

The argument min.int serves to avoid short fluctuations in the status growing season vs. no growing season by defining a minimum length of the status. If a time interval shorter than min.int is labeled as growing season or non-growing season, it is changed to the status of the neighboring values.

Value

a vector of type integer of the same length as the input GPPd in which 0 indicate no growing season (dormant season) and 1 indicate growing season.

bigleaf documentation built on Aug. 22, 2022, 9:09 a.m.