classGrowthIndex.f90 File Reference

Evaluates growth index used in calculating vegetation parameters for forests. More...

Functions/Subroutines
subroutine	classgrowthindex (GROWTH, TBAR, TA, FC, FCS, ILG, IG, IL1, IL2, JL)

Detailed Description

Evaluates growth index used in calculating vegetation parameters for forests.

Author

D. Verseghy, M. Lazare, V. Arora

The growth index that is calculated here varies from a value of 1 for periods when the trees are mature and fully leaved, to 0 for dormant and leafless periods, with a linear transition between the two. The transition periods are assumed to last for sixty days; therefore during these periods the growth index is incremented by \( \Delta t /5.184x10^6 \) where \(\Delta t\) is the time step in seconds.

The transition period from dormant to fully leafed is triggered when both the air temperature and the temperature of the first soil layer are above 2 C. If one of these conditions is not met afterwards, the growth index is reset back to 0. Increments are added continuously thereafter until the index reaches 1.

The transition from fully leafed to dormant is triggered when either the air temperature or the temperature of the first soil layer falls below 2 C. When this first happens at the end of the fully-leafed period, the growth index is set instantaneously to -1 and increments are continuously added from that point until the index reaches 0.

The absolute value of this growth index is utilized for performing calculations of various forest vegetation parameters in subroutine calcLandSurfParams; thus its shape as used there is that of a symmetrical trapezoidal function.

Function/Subroutine Documentation

classgrowthindex()

subroutine classgrowthindex	(	real, dimension(ilg), intent(inout)	GROWTH,
		real, dimension (ilg,ig), intent(in)	TBAR,
		real, dimension(ilg), intent(in)	TA,
		real, dimension(ilg), intent(in)	FC,
		real, dimension(ilg), intent(in)	FCS,
		integer, intent(in)	ILG,
		integer, intent(in)	IG,
		integer, intent(in)	IL1,
		integer, intent(in)	IL2,
		integer, intent(in)	JL
	)

Parameters

[in,out]	growth	Tree growth index [ ]
[in]	tbar	Temperature of soil layers [K]
[in]	ta	Air temperature [K]
[in]	fc	Fractional coverage of vegetation without snow on modelled area [ ]
[in]	fcs	Fractional coverage of vegetation with underlying snow pack on modelled area [ ]