pyMETRIC

Synopsis

This project contains Python code for Mapping EvapoTranspiration at high Resolution with Internalized Calibration model 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 script for easily running METRIC with satellite/airborne imagery.

Installation

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

python setup.py install

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

The following Python libraries will be required:

• pyTSEB
• pyTVDI
• Numpy
• Pandas
• GDAL

Code Example

High-level example

You can run METRIC with the scripts METRIClocalimagemain.py, which will read an input configuration file (default is ConfigLocalImage.txt). You can edit this configuration file or make a copy to fit your data and site characteristics and either run it in a Python GUI or in a terminal shell:

python TSEB_local_image_main.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

Low-level example

You can also run METRIC or any related process in python by importing the module METRIC from the pyMETRIC package. It will also import the ancillary modules (pyTSEB.resitances.py as res, pyTSEB.net_radiation as rad, pyTSEB.MO_similarity.py as MO, and pyTSEB.meteo_utils as met)

python import pyMETRIC.METRIC as METRIC output=METRIC.METRIC(Tr_K, T_A_K, u, ea, p, Sn, L_dn, emis, z_0M, d_0, z_u, z_T, cold_pixel, hot_pixel, LE_cold)

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

The direct and difuse shortwave radiation (Sn) and the downwelling longwave radiation (L_dn) can be estimated by

python emisAtm = TSEB.rad.calc_emiss_atm(ea,Ta_K_1) # Estimate atmospheric emissivity from vapour pressure (mb) and air Temperature (K) L_dn = emisAtm * TSEB.met.calc_stephan_boltzmann(Ta_K_1) # in W m-2 Sn = Sdn * (1.0 - albedo)

Basic Contents

Low-level modules

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

• .pyMETRIC/METRIC.py

  core functions for running METRIC.

• .pyMETRIC/endmember_search.py

  functions automatically finding the cold and hot pixels in an image

Main Scientific References

• Allen, R. G., Tasumi, M., and Trezza, R. (2007). Satellite-based energy balance for mapping evapotranspiration with internalized calibration (METRIC)—Model. Journal of irrigation and drainage engineering, 133(4), 380-394.
• Allen, Richard G., Boyd Burnett, William Kramber, Justin Huntington, Jeppe Kjaersgaard, Ayse Kilic, Carlos Kelly, and Ricardo Trezza, 2013. Automated Calibration of the METRIC Landsat Evapotranspiration Process. Journal of the American Water Resources Association (JAWRA) .49(3):563–576 https://doi.org/10.1111/jawr.12056
• Nishan Bhattarai, Lindi J. Quackenbush, Jungho Im, tephen B. Shaw, 2017. A new optimized algorithm for automating endmember pixel selection in the SEBAL and METRIC models. Remote Sensing of Environment, Volume 196, Pages 178-192, https://doi.org/10.1016/j.rse.2017.05.009.

Contributors

• Hector Nieto hector.nieto@irta.cat hector.nieto.solana@gmail.com main developer
• Radoslaw Guzinski main developer, tester

License

pyMETRIC: Python code for Mapping EvapoTranspiration at high Resolution with Internalized Calibration Model

Copyright 2018 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/.