This project contains Python code for Two Source Energy Balance models (Priestley-Taylor TSEB-PT, Dual Time Difference DTD and TSEB with component soil and canopy temperatures TSEB-2T) for estimating sensible and latent heat flux (evapotranspiration) based on measurements of radiometric surface temperature.

The project consists of:

1. lower-level modules with the basic functions needed in any resistance energy balance model

2. higher-level scripts for easily running TSEB with tabulated data and/or satellite/airborne imagery.

Download the project to your local system, enter the download directory and then type

python setup.py install

if you want to install pyTSEB and its low-level modules in your Python distribution.

The following Python libraries will be required for running TSEB over an image:

• Numpy
• GDAL

The easiest way to get a feeling of TSEB and its configuration is through the provided ipython/jupyter notebooks. In a terminal shell, navigate to your working folder and type

• jupyter notebook ProcessPointTimeSeries.ipynb

for configuring and running TSEB over a time series of tabulated data

• jupyter notebook ProcessLocalImage.ipynb

for configuring and running TSEB over an image/scene using local meteorological data

In addition, you can also run TSEB with the scripts MAIN_TSEB_LocalImage.py and MAIN_TSEB_PointTimeSeries.py, which will read an input configuration file (defaults are Config_LocalImage.txt and Config_PointTimeSeries.txt respectively). You can edit these configuration files or make a copy to fit your data and site characteristics and either run any of these two scripts in a Python GUI or in a terminal shell:

• python MAIN_TSEB_LocalImage.py <configuration file>

where <configuration file> points to a customized configuration file... leave it blank if you want to use the default file Config_LocalImage.txt

• python MAIN_TSEB_PointTimeSeries.py <configuration file>

where <configuration file> points to a customized configuration file... leave it blank if you want to use the default file Config_PointTimeSeries.txt

You can run any TSEB model or any related process in python by importing the module TSEB. It will also import the ancillary modules (resitances.py as res, netRadiation as rad, MOsimilarity.py as MO, ClumpingIndex.py as CI and meteoUtils.py as met)

import TSEB 
output=TSEB.TSEB_PT(Tr_K, vza, Ta_K, u, ea, p, Sdn_dir, Sdn_dif, fvis, fnir, sza, Lsky, LAI, hc, emisVeg, emisGrd, spectraVeg, spectraGrd, z_0M, d_0, zu, zt)

You can type help(TSEB.TSEB_PT) to understand better the inputs needed and the outputs returned

The direct and difuse shortwave radiation (Sdn_dir, Sdn_dif, fvis, fnir) and the downwelling longwave radiation (Lsky) can be estimated by

emisAtm = TSEB.rad.CalcEmiss_atm(ea,Ta_K_1) # Estimate atmospheric emissivity from vapour pressure (mb) and air Temperature (K)
Lsky = emisAtm * TSEB.met.CalcStephanBoltzmann(Ta_K_1) # in W m-2
difvis,difnir, fvis,fnir=TSEB.rad.CalcDifuseRatio(Sdn,sza,press=p, Wv=1) # fraction of difuse and PAR/NIR radiation from shortwave irradiance (W m-2, solar zenith angle, atmospheric pressure and precipitable water vapour )
Skyl=difvis*fvis+difnir*fnir # broadband difuse fraction
Sdn_dir=Sdn*(1.0-Skyl)
Sdn_dif=Sdn*Skyl

• .src/pyTSEB.py, class object for TSEB scripting

• ProcessPointTimeSeries.ipynb and ProcessLocalImage.ipynb notebooks for using TSEB and configuring TSEB through a Graphical User Interface, GUI

• MAIN_TSEB_LocalImage.py and MAIN_TSEB_PointTimeSeries.py, high level scripts for running TSEB through a configuration file (Config_LocalImage.txt or Config_PointTimeSeries.txt)

• TSEB_ProcessPointTimeSeries.ipynb notebook with more details about the high-level TSEB programming

• pyTSEB_in_Detail.ipynb notebook with a closer look at the low-level and high-level TSEB code

• TSEB_and_Resistances.ipynb notebook for undertanding the TSEB model and the estimation of resistances

The low-level modules in this project are aimed at providing customisation and more flexibility in running TSEB. The following modules are included

• .src/TSEB.py

core functions for running different TSEB models (TSEB_PT (*args,**kwargs), TSEB_2T(*args,**kwargs), DTD (*args,**kwargs)), or a One Source Energy Balance model (OSEB(*args,**kwargs)).

• .src/netRadiation.py

functions for estimating net radiation and its partitioning between soil and canopy

• .src/resistances.py

functions for estimating the different resistances for momemtum and heat transport and surface roughness

• .src/MOsimilarity.py

functions for computing adiabatic corrections for heat and momentum transport, Monin-Obukhov length, friction velocity and wind profiles

• .src/ClumpingIndex.py

functions for estimating the canopy clumping index and get effective values of Leaf Area Index

• .src/meteoUtils.py

functions for estimating meteorolgical-related variables such as density of air, heat capacity of air or latent heat of vaporization.

http://pytseb.readthedocs.org/en/latest/index.html

• Norman, J. M., Kustas, W. P., Prueger, J. H., and Diak, G. R.: Surface flux estimation using radiometric temperature: a dual-temperature-difference method to minimize measurement errors, Water Resour. Res., 36, 2263, doi: 10.1029/2000WR900033, 2000
• Norman, J., Kustas, W., and Humes, K.: A two-source approach for estimating soil and vegetation fluxes from observations of directional radiometric surface temperature, Agr. Forest Meteorol., 77, 263–293, doi: 10.1016/0168-1923(95)02265-Y, 1995
• Kustas, W. P. and Norman, J. M.: A two-source approach for estimating turbulent fluxes using multiple angle thermal infrared observations, Water Resour. Res., 33, 1495–1508, 199
• Kustas, W. P. and Norman, J. M.: Evaluation of soil and vegetation heat flux prediction using a simple two-source model with radiometric temperatures for partial canopy cover, Agr. Forest Meteorol., 94, 13–29, 199

The folder ./Input contains examples for running TSEB in a tabulated time series (ExampleTableInput.txt) and in an image (ExampleImage_< variable >.tif). Just run the high-level scripts with the configuration files provided by default and compare the resulting outputs with the files stored in ./Output/

• Hector Nieto [email protected] [email protected] main developer
• William P. Kustas TSEB modeling, tester
• Radoslaw Guzinski DTD code developer, tester
• Ana Andreu tester

pyTSEB: a Python Two Source Energy Balance Model

Copyright 2016 Hector Nieto and contributors.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.