## 3 Results
### Temporal Response of Satellite Information to Wet Pulses
#### 3.2.2 Land Surface Temperature  
Figures 5 and 2 show LST from MODIS, in situ LST and ETa in ASM and Ti Tree, respectively. ETa was estimated by the eddy covariance method (full description in [56]). A typical seasonal pattern in LST with minimum and maximum values in winter and summer, respectively, was observed. For the study periods, a relatively short temporal window between late November to March was considered. Thus, the effect of seasonal changes in LST on the correlations with SM is significantly low. However, this effect should be considered if the entire year is included in the analysis. The results show noticeable decreases during significant wet pulses (end of December 2016-mid-February 2017, December 2020-March 2021) due to evaporative cooling. Using an UAV thermal camera, [33] also reported low sensible heat flux during the summer of wet seasons. Maximum values (336-338 K) were evident in dry summer (February and December 2019). Terra and Aqua showed similar temporal shapes, with lower values from Terra (morning overpass). The general pattern of satellite LST was consistent with field measurements, indicating that satellite information is a good complement to monitor spatial changes in surface energy balance associated with significant wet pulses in this ecosystem. The difference between remotely sensed and in situ LST is explained by the design of the tower and the radiome  
Figure 4: Detailed temporal series of the EVI and LSW from the AHI and SM in ASM for each analyzed season: (**a**) 2017–2018 (normal), (**b**) 2018–2019 (moderately dry), (**c**) 2019–2020 (normal), (**d**) 2020–2021 (extremely wet). Lags between peaks in SM and spectral indices are included.  
ter ([[https://www.ozflux.org.au/monitoringsites/alicesprings/alicesprings_pictures.html](https://www.ozflux.org.au/monitoringsites/alicesprings/alicesprings_pictures.html)]([https://www.ozflux.org.au/monitoringsites/alicesprings/alicesprings_pictures.html](https://www.ozflux.org.au/monitoringsites/alicesprings/alicesprings_pictures.html)), accessed on 18 December 2024).  
Figure 6 shows the detailed temporal series of LST for the studied events in ASM. A quicker response of LST to wet pulses compared to spectral indices can be observed, decreasing the days after the event occurs and maintaining low values during variable temporal windows. That temporal effect of the evaporative cooling process is more noticeable during the wettest pulses (Figure 6a,e), which is associated with increases in ET, as reported by [35] for northern Australia. Those authors showed that vegetation can use available moisture resources rapidly, which can explain the quick fluctuations of LST after significant precipitation events. In general, minimum values (around 305 K) during wet pulses that occur in late spring and summer were observed when deep horizons showed high SM values (10 cm depth: 0.25-0.35 m\({}^{3}\)/m\({}^{3}\); 60 cm depth: 0.25-0.5 m\({}^{3}\)/m\({}^{3}\); 100 cm: 0.25-0.55 m\({}^{3}\)/m\({}^{3}\)).  
Figure 5: MYD/MOD11A1, in situ daily LST and actual evapotranspiration during the study period in ASM. In situ LST was calculated from upwelling longwave radiances measured by the pyrgeometer CNR1.