Eddy covariance (EC) systems are being used to measure sensible heat (H) and latent heat (LE) fluxes in order to determine crop water use or evapotranspiration (ET). The reliability of EC ...measurements depends on meeting certain meteorological assumptions; the most important of such are horizontal homogeneity, stationarity, and non-advective conditions. Over heterogeneous surfaces, the spatial context of the measurement must be known in order to properly interpret the magnitude of the heat flux measurement results. Over the past decades, there has been a proliferation of ‘heat flux source area’ (i.e., footprint) modeling studies, but only a few have explored the accuracy of the models over heterogeneous agricultural land. A composite ET estimate was created by using the estimated footprint weights for an EC system in the upwind corner of four fields and separate ET estimates from each of these fields. Three analytical footprint models were evaluated by comparing the composite ET to the measured ET. All three models performed consistently well, with an average mean bias error (MBE) of about −0.03 mm h−1 (−4.4%) and root mean square error (RMSE) of 0.09 mm h−1 (10.9%). The same three footprint models were then used to adjust the EC-measured ET to account for the fraction of the footprint that extended beyond the field of interest. The effectiveness of the footprint adjustment was determined by comparing the adjusted ET estimates with the lysimetric ET measurements from within the same field. This correction decreased the absolute hourly ET MBE by 8%, and the RMSE by 1%.
Coral bleaching is a stress response of corals induced by a variety of factors, but these events have become more frequent and intense in response to recent climate‐change‐related temperature ...anomalies. We tested the hypothesis that coral reefs affected by bleaching events are currently heavily infested by boring sponges, which are playing a significant role in the destruction of their physical structure. Seventeen reefs that cover the entire distributional range of corals along the Mexican Pacific coast were studied between 2005/2006, and later between 2009/2010. Most of these coral reefs were previously impacted by bleaching events, which resulted in coral mortalities. Sponge abundance and species richness was used as an indicator of bioerosion, and coral cover was used to describe the present condition of coral reefs. Coral reefs are currently highly invaded (46% of the samples examined) by a very high diversity of boring sponges (20 species); being the coral reef framework the substrate most invaded (56%) followed by the rubbles (45%), and the living colonies (36%). The results also indicated that boring sponges are promoting the dislodgment of live colonies and large fragments from the framework. In summary, the eastern coral reefs affected by bleaching phenomena, mainly provoked by El Niño, present a high diversity and abundance of boring sponges, which are weakening the union of the colony with the reef framework and promoting their dislodgment. These phenomena will probably become even more intense and severe, as temperatures are projected to continue to rise under the scenarios for future climate change, which could place many eastern coral reefs beyond their survival threshold.
We tested the hypothesis that coral reefs affected by bleaching events are currently heavily infested by boring sponges, which are playing a significant role in the destruction of their physical structure. Forty‐six percent of the more than 10,000 coral samples examined were invaded by boring sponges, and the results indicated that they are promoting the dislodgment of live colonies and large fragments from the framework, especially in reefs previously impacted by bleaching phenomena.
Medicinal plants grown in natural settings are exposed to different adverse environmental conditions that determine their growth and development as well as the composition and concentration of ...secondary metabolites in their organs. The objective of this study was to evaluate the effects of environmental conditions associated with localities and annual growth cycles on the contents of phenolic compounds and flavonoids, antioxidant activity and potentially bioactive phenolic acids in the roots of Eryngium montanum, a medicinal species from temperate Mexico. The samples for composition analysis were collected using a bifactorial design: Factor A consisted of the localities (Morelos and La Unión de San Martin Huamelulpam, Mexico) and Factor B was represented by the annual growth cycle (2020 and 2021). In each sample, the contents of polyphenols and equivalent flavonoids of quercetin and catechin and antioxidant activity were evaluated using spectrophotometry. Subsequently, chlorogenic, caffeic and rosmarinic acids were identified and quantified using high-performance liquid chromatography with diode-array detection (HPLC-DAD). The annual growth conditions and, to a lesser extent, the locality of origin of the samples significantly influenced the contents of phenolic compounds and antioxidant activity. The environmental conditions that occurred in 2021 favored an increase in the contents of phenolic compounds compared to those in 2020, and the same pattern was observed for chlorogenic acid; however, for caffeic and rosmarinic acids, the opposite pattern was observed. The content of phenolic acids in the roots of E. montanum follows different and independent patterns between cycles based on the interaction between the locality of origin and annual growth cycle. This study quantifies the magnitude of the total environmental effect on the phenolic compound concentrations in E. montanum roots, which was measured via sampling during two annual growth cycles, where the sampling locations factor had little influence. The bioactive compounds identified in E. montanum roots have the potential for use as alternative medicines, as mentioned by different families from Oaxaca, Mexico.
► Thermal energy balance model performance is evaluated under advective conditions. ► Use of remote meteorological data had a minor effect on DTD model performance. ► Variation in LST and LAI ...significantly affected both TSEB and DTD model output. ► With representative LST and LAI inputs, TSEB and DTD models compute reliable ET.
Application and validation of many thermal remote sensing-based energy balance models involve the use of local meteorological inputs of incoming solar radiation, wind speed and air temperature as well as accurate land surface temperature (LST), vegetation cover and surface flux measurements. For operational applications at large scales, such local information is not routinely available. In addition, the uncertainty in LST estimates can be several degrees due to sensor calibration issues, atmospheric effects and spatial variations in surface emissivity. Time differencing techniques using multi-temporal thermal remote sensing observations have been developed to reduce errors associated with deriving the surface-air temperature gradient, particularly in complex landscapes. The Dual-Temperature-Difference (DTD) method addresses these issues by utilizing the Two-Source Energy Balance (TSEB) model of Norman et al. (1995) 1, and is a relatively simple scheme requiring meteorological input from standard synoptic weather station networks or mesoscale modeling. A comparison of the TSEB and DTD schemes is performed using LST and flux observations from eddy covariance (EC) flux towers and large weighing lysimeters (LYs) in irrigated cotton fields collected during BEAREX08, a large-scale field experiment conducted in the semi-arid climate of the Texas High Plains as described by Evett et al. (2012) 2. Model output of the energy fluxes (i.e., net radiation, soil heat flux, sensible and latent heat flux) generated with DTD and TSEB using local and remote meteorological observations are compared with EC and LY observations. The DTD method is found to be significantly more robust in flux estimation compared to the TSEB using the remote meteorological observations. However, discrepancies between model and measured fluxes are also found to be significantly affected by the local inputs of LST and vegetation cover and the representativeness of the remote sensing observations with the local flux measurement footprint.
White light phosphors have many potential applications such as solid‐state lighting, full color displays, light source for plant growth, and crop improvement. However, most of these phosphors are ...rare‐earth‐based materials which are costly and would be facing the challenge of resource issue due to the extremely low abundance of these elements on earth. A new white color composite consisted of a graphitic‐phase nitrogen carbon (g‐C3N4) treated with nitric acid and copper‐cysteamine Cu3Cl(SR)2 is reported herein. Under a single wavelength excitation at 365 nm, these two materials show a strong blue and red luminescence, respectively. It is interesting to find that the white light emission with a quantum yield of 20% can be obtained by mixing these two self‐activated luminescent materials at the weight ratio of 1:1.67. Using a 365 nm near‐ultraviolet chip for excitation, the composite produces a white light‐emitting diode that exhibits an excellent color rendering index of 94.3. These white‐emitting materials are environment friendly, easy to synthesize, and cost‐effective. More importantly, this will potentially eliminate the challenge of rare earth resources. Furthermore, a single chip is used for excitation instead of a multichip, which can greatly reduce the cost of the devices.
Composites of g‐C3N4 and Cu3Cl(SR)2 emit white light when they are exited by a single chip at 365 nm. These non‐rare‐earth materials are cheap and easy to approach. They can be applied not only for solid lighting and displays but also for crop improvement.
A study was carried out to calibrate and validate the aerodynamic temperature method for estimating the spatial variability of the sensible (H) and latent (LE) heat fluxes over a drip-irrigated ...merlot vineyard located in the Maule Region, in Chile. For this study, measurement of energy balance components and meteorological data were collected from the 2006 to 2010 growing seasons. The experimental plot was composed of a 4.25 ha of 'Merlot' vineyard, which was equipped with an Eddy-Covariance system and an automatic weather station. The k-fold cross-validation method was utilized to tune and validate a vineyard surface aerodynamic temperature (T
aero
) model, considering all of the days when Landsat scenes and ground measurements of meteorological data and surface energy balance (SEB) were available. Then, the satellite-based estimations of T
aero
were utilized to calculate the surface aerodynamic resistance (r
ah
) and, subsequently, heat fluxes of H and LE. Results indicated that the estimated H and r
ah
values were not significantly different to those measured in the vineyard (95% significance level) showing a root mean square (RMSE) and mean absolute error (MAE) between 34-29 W m
−2
and 1.01-0.78 s m
−1
, respectively. Satellite-based computations of LE were somewhat higher than those measured at the time of satellite overpass (RMSE = 63 W m
−2
; MAE = 56 W m
−2
), presumably due to the biases embedded in the net radiation (R
n
) and soil heat flux (G) computations. The proposed SEB method based on T
aero
is very simple to implement, presenting similar accuracies on ET mapping to those computed by complex satellite-based models.
The total available water in the soil root zone (TAW
r
), which regulates the plant transpiration, is a critical parameter for irrigation management and hydrologic modeling studies. However, the TAW
...r
was not well-investigated in current hydrologic or agricultural research for two reasons: (1) there is no direct measurement method of this parameter; and (2) there is, in general, a large spatial and temporal variability of TAW
r
. In this study, we propose a framework to improve TAW
r
estimation by incorporating the crop water stress index (CWSI) from canopy temperature into the Food and Agriculture Organization of the United Nations (FAO) paper 56 water balance model. Field experiments of irrigation management were conducted for maize during the 2012, 2013 and 2015 growing seasons near Greeley, Colorado, USA. The performance of the FAO water balance model with CWSI-determined TAW
r
was validated using measured soil water deficit. The statistical analyses between modeled and observed soil water deficit indicated that the CWSI-determined TAW
r
significantly improved the performance of the soil water balance model, with reduction of the mean absolute error (MAE) and root mean squared error (RMSE) by 17 and 20%, respectively, compared with the standard FAO model (with experience estimated TAW
r
). The proposed procedure may not work under well-watered conditions, because TAW
r
may not influence the crop transpiration or crop water stress in both daily and seasonal scales under such conditions. The proposed procedure potentially could be applied in other ecosystems and with other crop water stress related measurements, such as surface evapotranspiration from remote sensing methodology.
AbstractAlfalfa hourly bulk surface resistance (rs) has been modeled as a function of crop biophysical characteristics. The new modeled rs allows the calculation of hourly alfalfa evapotranspiration ...(ET) using the Penman-Monteith (P-M) equation. In addition, another equation from the literature was also evaluated. The experiment took place during the 2009 and 2010 alfalfa growth seasons near Rocky Ford, Colorado. The results indicated that ET obtained from rs parameterized with leaf area index (LAI) or crop height (hc) was more accurate than ET calculated with conventionally obtained rs when evaluated with lysimetric data. In addition, for hc less than 25 cm, ET was remarkably better estimated with the new rs model than with conventional rs. However, for hc greater than 25 cm, the proposed rs was slightly better than conventional rs. The value of conventional rs was underestimated when hc was less than 25 cm. These underestimated rs values resulted in higher hourly alfalfa ET rates (20% in 2009 and 41.5% in 2010). By contrast, the new approach underestimated ET by 7.5% for hc less than 25 cm in 2009, and ET was overestimated by 7%–9% for the 2010 data set. The accuracy of ET with conventional rs in 2010 for the same short hc was poor, because the Nash-Sutcliffe coefficient of efficiency was negative. Therefore, using a variable rs for alfalfa as a function of LAI or hc improved the estimation of alfalfa hourly actual ET.
This paper pioneers a novel approach in electromagnetic (EM) system analysis by synergistically combining Bayesian Neural Networks (BNNs) informed by Latin Hypercube Sampling (LHS) with advanced ...thermal-mechanical surrogate modeling within COMSOL simulations for high-frequency low-pass filter modeling. Our methodology transcends traditional EM characterization by integrating physical dimension variability, thermal effects, mechanical deformation, and real-world operational conditions, thereby achieving a significant leap in predictive modeling fidelity. Through rigorous evaluation using Mean Squared Error (MSE), Maximum Learning Error (MLE), and Maximum Test Error (MTE) metrics, as well as comprehensive validation on unseen data, the model's robustness and generalization capability is demonstrated. This research challenges conventional methods, offering a nuanced understanding of multiphysical phenomena to enhance reliability and resilience in electronic component design and optimization. The integration of thermal variables alongside dimensional parameters marks a novel paradigm in filter performance analysis, significantly improving simulation accuracy. Our findings not only contribute to the body of knowledge in EM diagnostics and complex-environment analysis but also pave the way for future investigations into the fusion of machine learning with computational physics, promising transformative impacts across various applications, from telecommunications to medical devices.
► We model spatially distributed energy balance fluxes and evapotranspiration. ► We use high resolution airborne multispectral and thermal infrared imagery. ► We compare modeled fluxes and soil water ...content with measurements. ► Estimated soil water content is assimilated and used to update water balance. ► Improvements in soil water content estimates in the soil profile are obtained.
Remote sensing of evapotranspiration (ET) has evolved over the last 20 years with the development of more robust energy balance approaches and the availability of timely remotely sensed imagery from satellite sensors. This has allowed the use of remote sensing for near-real time water management in irrigated systems in the western United States. In this paper a hybrid ET approach is applied to irrigated and non-irrigated cotton fields at the BEAREX08 experimental site using airborne remote sensing inputs under highly advective conditions, taking advantage of the available root zone soil water content measurements for verification of model output. The modeling approach is based on coupling the Two-Source-Energy Balance (TSEB) and the reflectance-based crop coefficient models. The TSEB model provides estimates of real crop ET while the reflectance-based crop coefficient approach allows for updating the basal crop coefficient and the interpolation and extrapolation of ET between the dates of remote sensing inputs facilitating the maintenance of a soil water balance in the root zone of the crop. Actual ET estimates using the TSEB model were compared with measured ET using eddy covariance systems deployed in four cotton fields during the BEAREX08 experiment. Estimates of soil water content in the soil profile of both irrigated and rain fed cotton fields were compared with measurements at different depths using neutron probe observations. Data assimilation techniques were applied to update soil water content values using estimates based on actual ET from the TSEB model. Results indicate that the hybrid ET modeling approach using data assimilation produced reliable daily ET interpolated between remote sensing observations and significantly improved soil water content estimates throughout the root zone profile compared to applying the crop-coefficient technique in a water balance model without the actual ET inputs.
PDF
