Presented at the 3rd ICOS Science Conference in Prague, Czech Republic, 11-13 Sep 2018.

1. Quantifying evapotranspiration from satellite
retrievals of land surface temperature over a mosaic
landscape in the Czech Republic
*Milan Fischer1,2, Kyle Knipper3, František Jurečka1,2, Martha Anderson3, Gabriela Pozníková1,2, Zdeněk
Žalud1,2, Marian Pavelka1, Miroslav Trnka1,2
1. Global Change Research Institute CAS, Bělidla 986/4a, 603 00, Brno, the Czech Republic
2. Department of Agrosystems and Bioclimatology, Faculty of Agronomy, Mendel University in Brno,
Zemědělská 1, 613 00 Brno, the Czech Republic
3. United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA
ICOS science conference 2018,
session: In-situ and remote sensing observations

2. Evapotranspiration
Evapotranspiration (ET) is the key part of the land water balance.
• In-situ measurements
• Remote sensing
- complete in time
- complete in space

3. How much water loss is required to keep the soil and vegetation at the
observed temperatures under given known radiative energy inputs?
Fusion of satellites with different spatio-temporal resolution to obtain finer resolution.
ALEXI (Atmosphere-Land Exchange Inverse model)

4. Disaggregation of ALEXI - DisALEXI
Tool for validation of large scale ALEXI products and tool for finer resolution analyses.
Climate reanalysis
Linux server, Centos7,
Python, Perl, Fortran,
C++, Envi/IDL,
MODTRAN
Computing machine
CERES
Landsat
MODIS
Satellite data

5. DisALEXI
Setting up the MODIS and Landsat domains
Polkovice site (cropland)

6. Local validation at the field scale using EC measurements
LI7500A
Gill Windmaster
Ancillary meteo
Wheat field (~26 ha)

7. Results - comparison of DisALEXI and EC
Landsat

8. Comparing different resolution data for one single field (Polkovice site):
EC tower site
Results
Is the specific field contributing to heating or cooling of the landscape?

9. Is the specific field contributing to heating or cooling of the landscape?
Landsat imaging
Landsat (30 m)
(5 km)
(500 m)

10. Results cropland
forest
grassland
Landcover

11. Results
LandcoverET of different covers
Means:
495 mm yr-1
527 mm yr-1
472 mm yr-1

12. Summary
• Our study demonstrates that LST based remote sensing
techniques provide a physically based and effective means for
determining ET in a mosaic landscape.
• Frequent cloudiness compromised the quality of Landsat
DisALEXI outputs at daily time scale, however, its agreement with
EC at longer time scales and MODIS DisALEXI are promising.
• We confirm the necessity of treating EC data according to
different energy balance closure scenarios when ETEC is
compared with other techniques respecting mass and energy
conservation law.
• This analyses will be conducted across the entire CzeCOS
network covering tens of site-years.

13. This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic within the
National Sustainability Programme I (NPU I), grant number LO1415 and the grant Completion of the research
infrastructure CzeCOS to increase international quality of research of the global climate change impacts on
ecosystem processes CZ.02.1.01/0.0/0.0/16_013/0001609.
References:
• Anderson, M.C. et al., 2016a. Relationships between the evaporative stress index and winter
wheat and spring barley yield anomalies in the Czech Republic. Climate Research, 70(2-3):
215-230.
• Anderson, M.C. et al., 2016b. The Evaporative Stress Index as an indicator of agricultural
drought in Brazil: An assessment based on crop yield impacts. Remote Sensing of
Environment, 174: 82-99.
• Hain, C.R. and Anderson, M.C., 2017. Estimating morning change in land surface temperature
from MODIS day/night observations: Applications for surface energy balance modeling.
Geophysical Research Letters, 44(19): 9723-9733.
• Yang, Y. et al., 2017. Daily Landsat-scale evapotranspiration estimation over a forested
landscape in North Carolina, USA, using multi-satellite data fusion. Hydrology and Earth
System Sciences, 21: 1017-1037.
Thanks for your attention!