MO_similarity package

Created on Apr 6 2015 @author: Hector Nieto (hector.nieto@ica.csic.es)

DESCRIPTION

This package contains the main routines for estimating variables related to the
Monin-Obukhov (MO) Similarity Theory, such as MO length, adiabatic correctors

for heat and momentum transport. It requires the following package.

PACKAGE CONTENTS

Stability correction functions

  • calc_Psi_H() Adiabatic correction factor for heat transport.
  • calc_Psi_M() Adiabatic correction factor for momentum transport.
  • CalcPhi_M_Brutsaert() [Brutsaert1992] similarity function for momentum transfer.
  • CalcPhi_H_Dyer() [Dyer1974] similarity function for heat transfer.
  • CalcPhi_M_Dyer() [Dyer1974] similarity function for momentum transfer.
pyTSEB.MO_similarity.calc_L(ustar, T_A_K, rho, c_p, H, LE)[source]

Calculates the Monin-Obukhov length.

Parameters:
  • ustar (float) – friction velocity (m s-1).
  • T_A_K (float) – air temperature (Kelvin).
  • rho (float) – air density (kg m-3).
  • c_p (float) – Heat capacity of air at constant pressure (J kg-1 K-1).
  • H (float) – sensible heat flux (W m-2).
  • LE (float) – latent heat flux (W m-2).
Returns:

L – Obukhov stability length (m).
Return type:

float

References

[Brutsaert2005]Brutsaert, W. (2005). Hydrology: an introduction (Vol. 61, No. 8). Cambridge: Cambridge University Press.
pyTSEB.MO_similarity.calc_mo_length(ustar, T_A_K, rho, c_p, H)[source]

Calculates the Monin-Obukhov length.

Parameters:
  • ustar (float) – friction velocity (m s-1).
  • T_A_K (float) – air temperature (Kelvin).
  • rho (float) – air density (kg m-3).
  • c_p (float) – Heat capacity of air at constant pressure (J kg-1 K-1).
  • H (float) – sensible heat flux (W m-2).
  • LE (float) – latent heat flux (W m-2).
Returns:

L – Obukhov stability length (m).
Return type:

float

References

[Brutsaert2005]Brutsaert, W. (2005). Hydrology: an introduction (Vol. 61, No. 8). Cambridge: Cambridge University Press.
pyTSEB.MO_similarity.calc_mo_length_hv(ustar, T_A_K, rho, c_p, H, LE)[source]

Calculates the Monin-Obukhov length.

Parameters:
  • ustar (float) – friction velocity (m s-1).
  • T_A_K (float) – air temperature (Kelvin).
  • rho (float) – air density (kg m-3).
  • c_p (float) – Heat capacity of air at constant pressure (J kg-1 K-1).
  • H (float) – sensible heat flux (W m-2).
  • LE (float) – latent heat flux (W m-2).
Returns:

L – Obukhov stability length (m).
Return type:

float

References

[Brutsaert2005]Brutsaert, W. (2005). Hydrology: an introduction (Vol. 61, No. 8). Cambridge: Cambridge University Press.
pyTSEB.MO_similarity.calc_Psi_H(zoL)[source]

Calculates the adiabatic correction factor for heat transport.

Parameters:zoL (float) – stability coefficient (unitless).
Returns:Psi_H – adiabatic corrector factor fof heat transport (unitless).
Return type:float

References

[Brutsaert2005]Brutsaert, W. (2005). Hydrology: an introduction (Vol. 61, No. 8). Cambridge: Cambridge University Press.
pyTSEB.MO_similarity.psi_h_dyer(zol)[source]
pyTSEB.MO_similarity.psi_h_brutsaert(zol)[source]
pyTSEB.MO_similarity.calc_Psi_M(zoL)[source]

Adiabatic correction factor for momentum transport.

Parameters:zoL (float) – stability coefficient (unitless).
Returns:Psi_M – adiabatic corrector factor fof momentum transport (unitless).
Return type:float

References

[Brutsaert2005]Brutsaert, W. (2005). Hydrology: an introduction (Vol. 61, No. 8). Cambridge: Cambridge University Press.
pyTSEB.MO_similarity.psi_m_dyer(zol)[source]
pyTSEB.MO_similarity.psi_m_brutsaert(zol)[source]
pyTSEB.MO_similarity.calc_richardson(u, z_u, d_0, T_R0, T_R1, T_A0, T_A1)[source]

Richardson number.

Estimates the Bulk Richardson number for turbulence using time difference temperatures.

Parameters:
  • u (float) – Wind speed (m s-1).
  • z_u (float) – Wind speed measurement height (m).
  • d_0 (float) – Zero-plane displacement height (m).
  • T_R0 (float) – radiometric surface temperature at time 0 (K).
  • T_R1 (float) – radiometric surface temperature at time 1 (K).
  • T_A0 (float) – air temperature at time 0 (K).
  • T_A1 (float) – air temperature at time 1 (K).
Returns:

Ri – Richardson number.
Return type:

float

References

[Norman2000]Norman, J. M., W. P. Kustas, J. H. Prueger, and G. R. Diak (2000), Surface flux estimation using radiometric temperature: A dual-temperature-difference method to minimize measurement errors, Water Resour. Res., 36(8), 2263-2274, http://dx.doi.org/10.1029/2000WR900033.
pyTSEB.MO_similarity.calc_u_star(u, z_u, L, d_0, z_0M)[source]

Friction velocity.

Parameters:
  • u (float) – wind speed above the surface (m s-1).
  • z_u (float) – wind speed measurement height (m).
  • L (float) – Monin Obukhov stability length (m).
  • d_0 (float) – zero-plane displacement height (m).
  • z_0M (float) – aerodynamic roughness length for momentum transport (m).

References

[Brutsaert2005]Brutsaert, W. (2005). Hydrology: an introduction (Vol. 61, No. 8). Cambridge: Cambridge University Press.