Knowledge of evapotranspiration (ET) is essential for enhancing our understanding of the hydrological cycle, as well as for managing water resources, particularly in semi-arid regions. Remote sensing offers a comprehensive means of monitoring this phenomenon at different spatial and temporal intervals. Currently, several satellite methods exist and are used to assess ET at various spatial and temporal resolutions with various degrees of accuracy and precision. This research investigated the performance of three satellite-based ET algorithms and two global products, namely land surface temperature/vegetation index (TsVI), Penman-Monteith (PM), and the Meteosat Second Generation ET (MET) and the Global Land-surface Evaporation: the Amsterdam Methodology (GLEAM) global products, in two eco-regions of South Africa. Daily ET derived from the eddy covariance system from Skukuza, a sub-tropical, savanna biome, and large aperture boundary layer scintillometer system in Elandsberg, a Mediterranean, fynbos biome, during the dry and wet seasons, were used to evaluate the models. Low coefficients of determination (R 2 ) of between 0 and 0.45 were recorded on both sites, during both seasons. Although PM performed best during periods of high ET at both sites, results show it was outperformed by other models during low ET times. TsVI and MET were similarly accurate in the dry season in Skukuza, as GLEAM was the most accurate in Elandsberg during the wet season. The conclusion is that none of the models performed well, as shown by low R 2 and high errors in all the models. In essence, our results conclude that further investigation of the PM model is possible to improve its estimation of low ET measurements.

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We observe the "invisible-to-the-naked-eye" flames of tungsten and vanadium ethoxide aerosols when ignited at moderate laser excitation (0 < P laser < 70 W) by employing an IR thermo-graphic camera. No emission is seen in the visible range whether by the visible region cameras or by spectroscopy. The emissivity of the precursor solution measured was 0.80 and 0.75 for tungsten and vanadium ethoxide, respectively. The spectral emissivities of the tungsten and vanadium ethoxide flames measured using FTIR-spectrometer were used to calculate the pyrolysis flame temperature at various laser intensities and wavelengths. New energy balance equations have been derivedthe transient temperature one extended from HaggertyCannon equation and the other based on standard resonance analysis. Fitting these models to experimental data reveals that only small amounts (1.33% and 4.32%, respectively) of the laser power are used in the pyrolysis of the precursor ethoxide aerosols into the desired oxide nanostructures. The low levels of specific heat capacity values obtained in these sprays suggest that these are electronic heat capacities rather than lattice heat capacities; enthalpies are also obtained. The experimental temperature-laser power trends observed were in agreement with previous findings from Tenegal et al. (Chem. Phys. Lett. 335:155, 2001). The damping coefficients, and hence the saturation intensities confirm that the vanadium containing precursor liquid is harder to dissociate into final products than the tungsten precursor as observed experimentally.

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