## 5 Discussion
### Assessment of PT-JPL-Thermal vs. MOD16 ET in the Donana Region  
In the whole Donana region, MOD16 estimations were also significantly lower than the PT-JPL-thermal \(ET\) values (Figure 5). Yet, a high agreement between models' \(ET\) estimation was found in the whole region inter-annual dynamics (Figure 5b) and at a pixel level (Figure 9b) with \(\rho\) values around 0.8 in most of the pixels. As previously found by [PERSON] et al. [72], although \(VPD\) alone may fail to capture the seasonality of water stress in some areas (Figure 9a), the inter-annualvariability of water stress could be captured by _VPD_ alone in most areas (Figure 9b), which indicated the adaptation of this approach for inter-annual global studies [72]. The PT-JPL-thermal _ET_ estimations reasonably approached documented _ET_ rates in the region per land cover class. The mixed-irrigation areas were found to evapotranspiration 4-5 mm/day in the summertime by using the PT-JPL-thermal approach (Figure 6a,b) in accordance with the on-site calibrated WATEN _ET_ estimations in the mixed-irrigation BXII. In the rice fields, the irrigation supply is documented to be 6.3 mm/day on average in a five-month crop-cycle [73], which is reasonably approached by the PT-JPL-thermal _ET_ estimations (Figure 6c). Previous studies [74] in Mediterranean-climate wetlands showed similar _ET_ average values than those estimated by the PT-JPL-thermal from May to October (i.e., 6 mm/day with \(\sigma\) = 1.9 mm/day vs. 4 mm/day), which indicates that MOD16 may be underestimating evaporative fluxes (Figure 6d). [PERSON] et al. [75] obtained similar results in the world's largest wetland (Pantanal) with a significant _ET_ underestimation after winter and spring rainfall-periods. For the shrubland, (Figure 6e) MOD16 may underestimate _ET_ due to a land use characterized as poorly vegetated surfaces, which is seen in previous findings in the Central Great Plains of the United Sates [37]. Although MOD16 has been documented to overestimate _ET_ in forested areas over the Northeast Asia monsoon region [36; 76], it was found to underestimate _ET_ for coniferous forests under Mediterranean conditions as well (Figure 6f). Intra-annual dynamics derived from the PT-JPL-thermal _ET_ coincided with on-site irrigation management and natural ecosystems patterns in the region, while MOD16 _ET_ presented some inconsistencies. The two mixed-irrigation areas (BXII and left bank) showed maximum MOD16 _ET_ values in April contrary to the irrigation-patterns in the region (June to August), which were more accurately identified by the PT-JPL-thermal approach (Figure 6a,b). For the rice fields, both MOD16 and the PT-JPL-thermal identified maximum _ET_ values in July and August (Figure 6c) according to the rice fields management in the region, which involves a five-month cultivation-cycle from May to September after which plots are drained and rice is harvested in October [73]. In the natural ecosystems, maximum PT-JPL-thermal _ET_ fluxes were observed when the evaporative demand from the atmosphere _ETp_ was high and when water was available and easily accessible. The PT-JPL-thermal was able to capture the natural ecosystems different _ET_ patterns depending on their capability to access water. Therefore, the wetland _ET_ dynamics were accurately captured (Figure 6d), showing the highest _ET_ fluxes in April-May when water is available after rainfall and vegetation sprouts [77]. Our results match _ET_ intra-annual dynamics previously documented by [PERSON] et al. [74] in a similar Mediterranean-climate wetland in the Sacramento-San Joaquin Delta in California. For the shrubland (Figure 6e), maximum rates were observed later in the spring (i.e., around June) coincident with the spring green-up period, which is supported by deep infiltration of winter and early spring precipitation, which was previously observed by [PERSON] et al. [78] in semiarid shrublands.