test_ITC

Functions

test_ITC

Test for developed turbulent conditions using Integral Turbulence Characteristics (ITC).

test_ITC.test_ITC(w_prime, u_prime, T_prime, wT, zoL, u_star, lat)

Test for developed turbulent conditions using Integral Turbulence Characteristics (ITC).

This function implements the ITC test based on flux-variance similarity as described in Foken and Wichura (1996) and Thomas & Foken (2002). It evaluates the degree of developed turbulence by comparing measured and modeled standard deviations of wind components and temperature, normalized by appropriate scaling parameters.

Parameters:

• w_prime (numpy.ndarray) – High-frequency fluctuations of vertical wind velocity [m s⁻¹]

• u_prime (numpy.ndarray) – High-frequency fluctuations of horizontal wind velocity [m s⁻¹]

• T_prime (numpy.ndarray) – High-frequency fluctuations of temperature [K]

• wT (float) – Kinematic temperature flux <w’T’> [K m s⁻¹]

• zoL (float) – Monin-Obukhov stability parameter (z/L) z: measurement height [m] L: Obukhov length [m]

• u_star (float) – Friction velocity [m s⁻¹]

• lat (float) – Site latitude [degrees]

Returns:

• ITC_w (float) – Relative model deviation for vertical wind component ITC_w = |(σ_w/u_*)_model - (σ_w/u_*)_meas| / (σ_w/u_*)_model

• ITC_u (float) – Relative model deviation for horizontal wind component ITC_u = |(σ_u/u_*)_model - (σ_u/u_*)_meas| / (σ_u/u_*)_model

• ITC_T (float) – Relative model deviation for temperature ITC_T = |(σ_T/T_*)_model - (σ_T/T_*)_meas| / (σ_T/T_*)_model

Notes

References

[1]

Foken, T. and Wichura, B. (1996). Tools for quality assessment of surface-based flux measurements. Agricultural and Forest Meteorology, 78(1-2), 83-105.

[2]

Thomas, C. and Foken, T. (2002). Re-evaluation of integral turbulence characteristics and their parameterizations. 15th Conference on Boundary Layer and Turbulence. 15-19 July 2002, Wageningen, The Netherlands.

See also

test_steady_state_FW96

Test for steady state conditions

test_steady_state_M98

Alternative steady state test

Examples

>>> # Example with unstable conditions
>>> w = np.random.normal(0, 0.3, 18000)  # 30 min at 10 Hz
>>> u = np.random.normal(0, 0.5, 18000)
>>> T = np.random.normal(0, 0.1, 18000)
>>> wT = -0.1  # Upward heat flux
>>> zoL = -0.5  # Unstable
>>> u_star = 0.4
>>> lat = 50.0
>>> ITC_w, ITC_u, ITC_T = test_ITC(w, u, T, wT, zoL, u_star, lat)

Author

Written by Bernard Heinesch (May 2022) University of Liege, Gembloux Agro-Bio Tech Based on EddyPro v7.0.4 implementation