Estimation of evapotranspiration fluxes over mustard using a Two-Source Energy Balance model

Abstract

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A Two-Source Energy Balance (TSEB) model computes surface energy fluxes using soil surface temperature and canopy temperature. An experiment was carried out in a research farm near the agrometeorological observatory, at Anand, India to parameterize the TSEB model for the mustard (Brassica Juncea) crop, to estimate surface energy fluxes and validate the TSEB-2T model. The TSEB-2T model was validated using net radiation measurements. Results revealed that modeled net radiation under all sowings. Very late sowing had comparatively high d_r 0.61, r 0.78** and low RMSE 58.12 Wm⁻², MAE 46.47 Wm⁻² and low MBE 1.66. Net radiation over mustard ranged from 269 to 538 Wm⁻² with relatively high peaks in the second sowing date. Sensible heat flux was relatively high during early growth and after the seed development phase. Latent heat flux and sensible heat flux had inverse partitioning patterns during the crop cycle of the mustard. Ground heat flux had negligible partitioning from net radiation after the seed initiation stage. During vegetative to pod initiation phases, the net radiation fraction for latent heat was high compared to sensible heat. Peak daily evapotranspiration based on modeled latent heat during the flowering to pod initiation phase was about 3.7 mm day⁻¹.