Preprints
https://doi.org/10.5194/bg-2021-356
https://doi.org/10.5194/bg-2021-356
 
16 Feb 2022
16 Feb 2022
Status: a revised version of this preprint was accepted for the journal BG and is expected to appear here in due course.

A Coupled Ground Heat Flux-Surface Energy Balance Model of Evaporation Using Thermal Remote Sensing Observations

Devansh Desai1,11, Kaniska Mallick2,10, Bimal Bhattacharya3, Ganapati S. Bhat4, Ross Morrison5, Jamie Cleverly6, Will Woodgate7, Jason Beringer8, Kerry Cawse-Nicholson9, Siyan Ma10, Joseph Verfaillie10, and Dennis Baldocchi10 Devansh Desai et al.
  • 1Department of Physics, Electronics & Space Sciences, Gujarat University, Ahmedabad, India
  • 2Remote Sensing and Natural Resources Modeling, Department ERIN, Luxembourg Institute of Science and Technology, Belvaux, L4422, Luxembourg
  • 3Agriculture & land Ecosystem Division, Space Applications Center, ISRO, Ahmedabad, India
  • 4Centre for Atmosphere and Oceanic Studies, Indian Institute of Sciences, Bengaluru, India
  • 5Centre for Ecology and Hydrology, Lancaster, UK
  • 6Terrestrial Ecosystem Research Network, College of Science and Engineering, James Cook University, Cairns, Queensland
  • 7CSIRO Land and Water, Private Bag 5, Floreat 6913, Western Australia
  • 8School of Earth and Environment (SEE), The University of Western Australia, WA, 6009, Australia
  • 9Carbon Cycles and Ecosystems, Jet Propulsion Laboratory, California Institute of Technology, United States
  • 10Environemtal Science Policy and Management, University of California, Berkeley, United States
  • 11Department of Physics, Institute of Science, Silver Oak University, Ahmedabad, Gujarat, India

Abstract. The major undetermined problem in evaporation (ET) retrieval using thermal infrared (TIR) remote sensing is the lack of a physically based ground heat flux (G) model and its amalgamation with surface energy balance (SEB) model. Here, we present a novel approach based on coupling a thermal inertia (TI)-based mechanistic G model with an analytical SEB model (Surface Temperature Initiated Closure) (STIC, version STIC1.2). The coupled model is named as STIC-TI and it uses noon-night land surface temperature (TS), surface albedo and vegetation index from MODIS Aqua in conjunction with a clear-sky net radiation model and ancillary meteorological information. The SEB flux estimates from STIC-TI were evaluated with respect to the in-situ fluxes from Eddy Covariance (EC) measurements in diverse agriculture and natural ecosystems of contrasting aridity in the northern hemisphere (e.g., India, United States of America) and southern hemisphere (e.g., Australia). Sensitivity analysis revealed substantial sensitivity of the STIC-TI derived fluxes due to TS uncertainty and partial compensation of sensitivity of G to TS due to the nature of the equations used in the TI-based G model. An evaluation of STIC-TI G estimates with respect to in-situ measurements showed an error range of 12–21 % across six flux tower sites in both the hemispheres. A comparison of STIC-TI G estimates with other G models revealed substantially better performance of the former. While the instantaneous noontime net radiation (RNi) and latent heat flux (LEi) was overestimated (15 % and 25 %), sensible heat flux (Hi) was underestimated with error of 22 %. The errors in Gi were associated with the errors in daytime TS and mismatch of footprint between the model estimates and measurements. Overestimation (underestimation) of LEi (Hi) was associated with the overestimation of net available energy (RNi – Gi) and use of unclosed SEB measurements. Being independent of any leaf-scale conductance parameterization and having a coupled sub-model of G, STIC-TI can make valuable contribution to map and monitor water stress and evaporation in the terrestrial ecosystems using noon-night thermal infrared observations from existing and future EO missions such as INSAT 4th generation and TRISHNA.

Devansh Desai et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2021-356', Anonymous Referee #1, 09 Mar 2022
  • RC2: 'Comment on bg-2021-356', Anonymous Referee #2, 14 Mar 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on bg-2021-356', Anonymous Referee #1, 09 Mar 2022
  • RC2: 'Comment on bg-2021-356', Anonymous Referee #2, 14 Mar 2022

Devansh Desai et al.

Data sets

Data set for A Coupled Ground Heat Flux-Surface Energy Balance Model of Evaporation Using Thermal Remote Sensing Observations Desai, Devansh; Mallick, Kaniska; Bhattacharya, B. K.; Bhat, G. S.; Morrison, Ross; Clevery, Jamie; Woodgate, Will; Beringer, Jason; Kerry Cawse-Nicholson; Ma, Siyan; Varfaillie, Joe; Baldocchi, Dennis https://doi.org/10.5281/zenodo.5806501

Devansh Desai et al.

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Short summary
Evaporation retrieval in the water-scarce environments is challenging due to empirical estimation of ground heat flux and complex parameterizations of conductances. We developed a parameter-sparse coupled ground heat flux-evaporation model and tested across different limits of water stress and vegetation fraction in northern and southern hemispheres. The model performed particularly well in the savannas and showed good potential to estimate ecosystem stress from thermal infrared satellites.
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