clumping_index package

Created on Apr 6 2015 @author: Hector Nieto (hnieto@ias.csic.es)

Modified on Mar 28 2016 @author: Hector Nieto (hnieto@ias.csic.es)

DESCRIPTION

Routines for calculating the clumping index for both randomly placed canopies and structured row crops such as vineyards.

PACKAGE CONTENTS

pyTSEB.clumping_index.calc_omega0_Kustas(LAI, f_C, x_LAD=1, isLAIeff=True)[source]

Nadir viewing clmping factor

Estimates the clumping factor forcing equal gap fraction between the real canopy and the homogeneous case, after [Kustas1999].

Parameters:
  • LAI (float) – Leaf Area Index, it can be either the effective LAI or the real LAI , default input LAI is effective.
  • f_C (float) – Apparent fractional cover, estimated from large gaps, means that are still gaps within the canopy to be quantified.
  • x_LAD (float, optional) – Chi parameter for the ellipsoildal Leaf Angle Distribution function of [Campbell1988] [default=1, spherical LIDF].
  • isLAIeff (bool, optional) – Defines whether the input LAI is effective or local.
Returns:

omega0 – clumping index at nadir.

Return type:

float

References

[Kustas1999]William P Kustas, John M Norman, Evaluation of soil and vegetation heat flux predictions using a simple two-source model with radiometric temperatures for partial canopy cover, Agricultural and Forest Meteorology, Volume 94, Issue 1, Pages 13-29, http://dx.doi.org/10.1016/S0168-1923(99)00005-2.
[Campbell1998]Campbell, G. S. & Norman, J. M. (1998), An introduction to environmental biophysics. Springer, New York https://archive.org/details/AnIntroductionToEnvironmentalBiophysics.
pyTSEB.clumping_index.calc_omega_Kustas(omega0, theta, w_C=1)[source]

Clumping index at an incidence angle.

Estimates the clumping index for a given incidence angle assuming randomnly placed canopies.

Parameters:
  • omega0 (float) – clumping index at nadir, estimated for instance by calc_omega0_Kustas().
  • theta (float) – incidence angle (degrees).
  • w_C (float, optional) – canopy witdth to height ratio, [default = 1].
Returns:

Omega – Clumping index at an incidenc angle.

Return type:

float

References

[Kustas1999]William P Kustas, John M Norman, Evaluation of soil and vegetation heat flux predictions using a simple two-source model with radiometric temperatures for partial canopy cover, Agricultural and Forest Meteorology, Volume 94, Issue 1, Pages 13-29, http://dx.doi.org/10.1016/S0168-1923(99)00005-2.
pyTSEB.clumping_index.calc_omega_rows(lai, f_c0, theta=0, psi=0, w_c=1, x_lad=1, is_lai_eff=True)[source]

Clumping index in row crops. Calculates the clumping index for a given incidence angle assuming structured row crops. :param lai: Leaf Area Index, it can be either the effective LAI or the real LAI

depending on isLAIeff, default input LAI is effective.
Parameters:
  • f_c0 (float) – Apparent nadir fractional cover, can be expresses as canopy width/row spacing.
  • theta (float, optional) – Incidence angle (degrees), default nadir.
  • psi (float, optional) – relative row-sun azimiuth angle
  • w_c (float, optional) – canopy witdht to height ratio, [default = 1].
  • x_lad (float, optional) – Chi parameter for the ellipsoildal Leaf Angle Distribution function of [Campbell1988] [default=1, spherical LIDF].
  • is_lai_eff (bool, optional) – Defines whether the input LAI is effective or real. [default True]
Returns:

omega – clumping index at an incidence angle.

Return type:

float

References

[Parry2018]Parry, C. K., H. Nieto, P. Guillevic, N. Agam, W. P. Kustas, J. Alfieri, L. McKee, and A. J. McElrone. An intercomparison of radiation partitioning models in vineyard canopies. Irrigation Science. Pages 1-14. https://doi.org/10.1007/s00271-019-00621-x.