JUAN CARLOS LÓPEZ SÁNCHEZ - Academia.edu (original) (raw)
Papers by JUAN CARLOS LÓPEZ SÁNCHEZ
Agronomy
The expansion of irrigated almond orchards in arid and semi-arid areas with scarce water availabl... more The expansion of irrigated almond orchards in arid and semi-arid areas with scarce water available raises key issues related to the sustainability of the water resources. A 3-year field experiment was conducted on a commercial young almond orchard located in the southeast of Spain to study the effect of two drip irrigation systems (surface, DI and subsurface, SDI) on almond crop growth and their physiological responses under fully-irrigated conditions. Crop evapotranspiration (ETc) and its components (crop transpiration, Tc and soil evaporation, Es) were monitored as well as the irrigation water and nitrogen productivities. To estimate ETc, a simplified two-source energy balance (STSEB) approach was used. Although a lower irrigation water amount was applied in SDI compared to DI (differences between 10% and 13.8%), the almond crop growth and physiological responses as well as the yield components and kernel yield showed no significant differences. The ETc estimates resulted in small...
Remote Sensing
Almost fifty years have passed since the idea to retrieve a value for Evapotranspiration (ET) usi... more Almost fifty years have passed since the idea to retrieve a value for Evapotranspiration (ET) using remote sensing techniques was first considered. Numerous ET models have been proposed, validated and improved along these five decades, as the satellites and sensors onboard were enhanced. This study reviews most of the efforts in the progress towards providing a trustworthy value of ET by means of thermal remote sensing data. It starts with an in-depth reflection of the surface energy balance concept and of each of its terms, followed by the description of the approaches taken by remote sensing models to estimate ET from it in the last thirty years. This work also includes a chronological review of the modifications suggested by several researchers, as well as representative validations studies of such ET models. Present limitations of ET estimated with remote sensors onboard orbiting satellites, as well as at surface level, are raised. Current trends to face such limitations and a f...
Water
Encouraged by the necessity to better understand the water use in this woody crop, a study was ca... more Encouraged by the necessity to better understand the water use in this woody crop, a study was carried out in a commercial drip-irrigated young almond orchard to quantify and monitor the crop evapotranspiration (ETc) and its partitioning into tree canopy transpiration (T) and soil evaporation (E), to list and analyze single and dual crop coefficients, and to extract relationships between them and the vegetation fractional cover (fc) and remote-sensing-derived vegetation indices (VIs). A Simplified Two-Source Energy Balance (STSEB) model was applied, and the results were compared to ground measurements from a flux tower. This study comprises three consecutive growing seasons from 2017 to 2019, corresponding to Years 2 to 4 after planting. Uncertainties lower than 50 W m−2 were obtained for all terms of the energy balance equation on an instantaneous scale, with average estimation errors of 0.06 mm h−1 and 0.6 mm d−1, for hourly and daily ETc, respectively. Water use for our young alm...
Remote Sensing
Monitoring Land Surface Temperature (LST) from Landsat satellites has been shown to be effective ... more Monitoring Land Surface Temperature (LST) from Landsat satellites has been shown to be effective in the estimation of crop water needs and modeling water use efficiency. Accurate LST estimation becomes critical in semiarid areas under water scarcity scenarios. This work shows the assessment of some well-known Single-Channel (SC) and Split-Window (SW) algorithms, adapted to Landsat 8/TIRS, under the conditions of a high-contrast semiarid agroecosystem. The recently released Landsat 8 Level-2 LST product (L8_ST) has also been included in the performance analysis. Ground measurements of surface temperature were taken for the evaluation during the summers of 2018–2019 in the cropland area of the Barrax test site, Spain. A dataset of 44 ground samples and 11 different L8/TIRS dates/scenes was gathered, covering a variety of crop fields and surface conditions. In addition, a simplified Single Band Atmospheric Correction (L-SBAC) was introduced based on a linearization of the atmospheric c...
Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requireme... more Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requirements. An alternative to the traditional crop-coefficient methods are the energy balance models. The objective of this research was to show how surface temperature observations can be used, together with a two-source energy balance model, to determine crop water use throughout the different phenological stages of a crop grown. Radiometric temperatures were collected in a sorghum (Sorghum bicolor) field as part of an experimental campaign carried out in Barrax, Spain, during the 2010 summer growing season. Performance of the Simplified Two-Source Energy Balance (STSEB) model was evaluated by comparison of estimated ET with values measured on a weighing lysimeter. Errors of ±0.14 mm h −1 and ±1.0 mm d −1 were obtained at hourly and daily scales, respectively. Total accumulated crop water use during the campaign was underestimated by 5 %. It is then shown that thermal radiometry can provide precise crop water necessities and is a promising tool for irrigation management. 1 Introduction Understanding the surface actual evapotranspiration (ET) is essential for managers responsible for planning and managing water resources, especially in arid and semi-arid regions where crop water demand generally exceeds precipitation and irrigation from surface and/or groundwater resources is then required to meet the deficit. This is particularly important in areas where water usage is regulated due
Forest fires are one of the most dangerous natural hazards, especially when they are recurrent. I... more Forest fires are one of the most dangerous natural hazards, especially when they are recurrent. In areas such as Galicia (Spain), forest fires are frequent and devastating. The development of fire risk models becomes a very important prevention task for these regions. Vegetation and moisture indices can be used to monitor vegetation status; however, the different indices may perform differently depending on the vegetation species. Eight different spectral indices were selected to determine the most appropriate index in Galicia. This study was extended to the adjacent region of Asturias. Six years of MODIS (Moderate Resolution Imaging Spectroradiometer) images, together with ground fire data in a 10 × 10 km grid basis were used. The percentage of fire events met the variations suffered by some of the spectral indices, following a linear regression in both Galicia and Asturias. The Enhanced Vegetation Index (EVI) was the index leading to the best results. Based on these results, a simple fire danger model was established, using logistic regression, by combining the EVI variation with other variables, such as fire history in each cell and period of the year. A seventy percent overall concordance was obtained between estimated and observed fire frequency.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2021
Quantifying spatial and temporal patterns of the actual evapotranspiration (ET) using Earth obser... more Quantifying spatial and temporal patterns of the actual evapotranspiration (ET) using Earth observation data can significantly contribute to the accurate and transparent monitoring of sustainable development goals (SDGs) target 6.4, which focuses on the increase of the water-use efficiency and sustainable freshwater withdrawals. Irrigated agriculture is by far the largest consumer of freshwater worldwide, and ET can serve as a direct proxy of crop water use. Various ongoing initiatives encourage the use of remote sensing data for the monitoring of SDG 6.4, including the WaPOR portal run by the Food and Agriculture Organization of the United Nations. However, none of these initiatives use Copernicus satellite and modeled data to the fullest extent. Copernicus provides operational high-quality data freely and openly, contains all the inputs required for ET modeling, and has long-term continuity and evolution plans, thus allowing for the establishment of baseline for SDG 6.4 and continuous monitoring in mid-and long term. In this study, we evaluate the utility of Copernicus data for this task with WaPOR products serving as a comparison benchmark. Thus, the modeled ET has to be able to accurately capture the field-scale activity at 10-day timesteps while also scaling to national coverage and providing consistent estimates at different spatial resolutions, ranging from tens to hundreds of meters. Results indicate that
Wheat is one of the crops occupying the largest areas in the world (218 million ha in 2013). Unde... more Wheat is one of the crops occupying the largest areas in the world (218 million ha in 2013). Understanding the land-atmosphere energy exchanges over these croplands becomes important not only for agronomy but also for climatic and meteorological aspects. This study continues previous work on the estimation of actual evapotranspiration and the assessment of crop coefficients of sorghum, sunflower, or canola. Two variations of a simple two-source energy balance (STSEB) approach were used in combination with land surface temperature measurements to calculate hourly and daily values of surface fluxes and actual evapotranspiration (ET). An experiment was carried out during the spring season of 2014 in Las Tiesas experimental farm in Barrax, Spain. Soil and canopy temperature components together with meteorological variables and biophysical parameters were measured from planting to senescence. Comparison to lysimeter measurements showed calculation errors of ±0.11 mm h-1 and ±0.8 mm d-1 for hourly and daily ET values, respectively, whereas an underestimation no greater than 4% resulted from the entire campaign. Partition between soil and canopy components yielded a ratio of evaporation (E) to transpiration (T) of 36% to 64%, respectively, for the total growing season. Dual crop coefficients were also calculated and compared to those proposed by FAO56. Although separate E and T measurements were not available, similar results between the STSEB and FAO 56 models demonstrate the utility of the STSEB for investigating management strategies aimed at increasing crop water use efficiency.
Remote. Sens., 2021
The combination of the state-of-the-art in the thermal infrared (TIR) domain [...]
Past and present of the Spanish folletín novel The optimal conditions for the creation of a popul... more Past and present of the Spanish folletín novel The optimal conditions for the creation of a popular novel occurred in the 19 th century. With the influence, first of all, of French literature, there was in Spain a huge production of these works, known in Spanish as 'folletines' or folletín novel. Its importance for the study of literature is undeniable. It is possible to detect its legacy in the best Spanish novel between 1870 and 1936, for instance in Benito Pérez Galdós or Pío Baroja. But it is also interesting to compare this folletín novel with the modern bestseller. Similar techniques and conception of what should be a novel are to find in modern bestseller Spanish writers such as Carlos Zafón, Eduardo Mendoza or Arturo Pérez-Reverte. In this article, they are compared with the famous 'folletinistas' of the second half of the 19 th century: Manuel
Remote Sensing, 2021
This work aims to validate the wide use of an algorithm developed using genetic programing (GP) t... more This work aims to validate the wide use of an algorithm developed using genetic programing (GP) techniques allowing to discern between water and non-water pixels using the near infrared band and different thresholds. A total of 34 wetlands and shallow lakes of 18 ecological types were used for validation. These include marshes, salt ponds, and saline and freshwater, temporary and permanent shallow lakes. Furthermore, based on the spectral matching between Landsat and Sentinel-2 sensors, this methodology was applied to Sentinel-2 imagery, improving the spatial and temporal resolution. When compared to other techniques, GP showed better accuracy (over 85% in most cases) and acceptable kappa values in the estimation of water pixels (κ ≥ 0.7) in 10 of the 18 assayed ecological types evaluated with Landsat-7 and Sentinel-2 imagery. The improvements were especially achieved for temporary lakes and wetlands, where existing algorithms were scarcely reliable. This shows that GP algorithms ap...
The Egyptian Journal of Remote Sensing and Space Science, 2020
The Pampas Region is a big plain of approximately 520,000 km 2 in Argentina. It is essential to e... more The Pampas Region is a big plain of approximately 520,000 km 2 in Argentina. It is essential to estimate evapotranspiration (ET) in this region since the primary productivity is directly linked to water availability. Information provided by satellite missions allows monitoring the spatial and temporal variability of ET. In the current study, we evaluated the version 006 of MOD16A2 product (MOD16A2.006) of Potential Evapotranspiration (ETp) and Actual Evapotranspiration (ETa) in Argentinian Pampas Region (APR). MOD16A2.006 product was compared with Crop Evapotranspiration (ETc), calculated with local measurements from the Oficina de Riesgo Agropecuario (ORA), and Crop Coefficient (Kc) data (function of Normalized Difference Vegetation Index (NDVI)) in seven stations in the APR from 2009 to 2018. We evaluated ETa at two temporal scales: accumulated values (mm) per growth stages (soybean crop), and 8-day accumulated values (mm8d À1). The results showed a systematic overestimation around 65% for ETp (MOD16A2.006) (found and eliminated by means of a linear function) and underestimation (in most stations) for ETa (MOD16A2.006) in accumulated values per growth stages. Respect to mm8d À1 , no systematic error was observed, but the relationship ETa (ORA) À ETa (MOD16A2.006) for soybean crop behaves similarly throughout APR.
Remote Sensing, 2020
Downscaling techniques offer a solution to the lack of high-resolution satellite Thermal InfraRed... more Downscaling techniques offer a solution to the lack of high-resolution satellite Thermal InfraRed (TIR) data and can bridge the gap until operational TIR missions accomplishing spatio-temporal requirements are available. These techniques are generally based on the Visible Near InfraRed (VNIR)-TIR variable relations at a coarse spatial resolution, and the assumption that the relationship between spectral bands is independent of the spatial resolution. In this work, we adopted a previous downscaling method and introduced some adjustments to the original formulation to improve the model performance. Maps of Land Surface Temperature (LST) with 10-m spatial resolution were obtained as output from the combination of MODIS/Sentinel-2 images. An experiment was conducted in an agricultural area located in the Barrax test site, Spain (39°03′35″ N, 2°06′ W), for the summer of 2018. Ground measurements of LST transects collocated with the MODIS overpasses were used for a robust local validation...
Revista Brasileira de Engenharia Agrícola e Ambiental, 2020
The estimate of the actual surface evapotranspiration (ET) contributes to quantifying the water n... more The estimate of the actual surface evapotranspiration (ET) contributes to quantifying the water needs of crops. An alternative to the use of lysimeter for an accurate estimation of water needs, which has proved to be of great value in recent years, is the use of remote sensing combined with models based on surface energy balance. There is wide variety of models that can be classified into two types: one-source models, such as the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) algorithm, or two-source models, such as the Simplified Two-Source Energy Balance (STSEB). The objective of this study was to analyze how METRIC and STSEB can be used to estimate ET, in comparison with the lysimeter data, for the different stages of development of the sorghum crop in Apodi, RN, Brazil. The accuracy of both models in the daily ET estimation for the semi-arid conditions of the experiment, with RMSE values of 0.8 and of 0.7 mm d-1 through METRIC and STSEB, res...
Slovo a smysl, 2019
SYNOPSIS Cervantes and Tolerance The treatment of the morisco theme in Don Quixote could be under... more SYNOPSIS Cervantes and Tolerance The treatment of the morisco theme in Don Quixote could be understood as an index-a proof-of the philosophical and spiritual differences between Cervantes and the official ideology of his time. In his discourse, Ricote (the morisco character in Don Quixote II, 1615) names the 'freedom of conscience', an important theme in European religious discourse of the 16 th and 17 th centuries. This article deals with the interpretation of that expression in the literary and ideological context of Cervantesʼ novel and Cervantesʼ world. It seems that the expression refers to the Peace of Augsburg, and it could be interpreted as an appeal for tolerance, in this case regarding the morisco question (the moriscos were banned in 1609, before the publication of the second volume of Don Quixote). Yet this is a problematic interpretation: in Spain, the expression was commonly associated with heresy. It is in this sense that Lope de Vega uses the expression. This in turn is what allows us to characterize Lope de Vegaʼs literary work as conservative and Cervantesʼ as liberal.
Remote Sensing, 2018
Monitoring Land Surface Temperature (LST) from satellite remote sensing requires an accurate corr... more Monitoring Land Surface Temperature (LST) from satellite remote sensing requires an accurate correction of the atmospheric effects. Although thermal remote sensing techniques have advanced significantly over the past few decades, to date, single-band pixel-by-pixel atmospheric correction of full thermal images is unsolved. In this work, we introduce a new Single-Band Atmospheric Correction (SBAC) tool that provides pixel-by-pixel atmospheric correction parameters regardless of the pixel size. The SBAC tool uses National Centers of Environmental Prediction (NCEP) profiles as inputs and, as a novelty, it also accounts for pixel elevation through a Digital Elevation Model (DEM). Application of SBAC to 19 Landsat 7-ETM+ scenes shows the potential of the proposed pixel-by-pixel atmospheric correction to capture terrain orography or atmospheric variability within the scene. LST estimation yields negligible bias and an RMSE of ±1.6 K for the full dataset. The Landsat Atmospheric Correction Tool (ACT) is also considered for comparison. SBAC-ACT LST deviations are analyzed in terms of distance to the image center, surface elevation, and spatial distribution of the atmospheric water content. Differences within 3 K are observed. These results give us the first insight of the potential of SBAC for the operational pixel-by-pixel atmospheric correction of full thermal images. The SBAC tool is expected to help users of satellite single-channel thermal sensors to improve their LST estimates due to its simplicity and robustness.
Hipogrifo. Revista de literatura y cultura del Siglo de Oro, 2019
Táto práce vznikla v rámce grantu PROGRES Q14: Krize racionality v moderním myšlení. (Este trabaj... more Táto práce vznikla v rámce grantu PROGRES Q14: Krize racionality v moderním myšlení. (Este trabajo ha surgido en el marco de proyecto de investigación PROGRES Q14: La crisis de la racionalidad en el pensamiento moderno).
SIAM Journal on Applied Dynamical Systems, 2015
A methodology to track bifurcations of periodic orbits in large-scale dissipative systems dependi... more A methodology to track bifurcations of periodic orbits in large-scale dissipative systems depending on two parameters is presented. It is based on the application of iterative Newton-Krylov techniques to extended systems. To evaluate the action of the Jacobian it is necessary to integrate variational equations up to second order. It is shown that this is possible by integrating systems of dimension at most four times that of the original equations. In order to check the robustness of the method, the thermal convection of a mixture of two fluids in a rectangular domain has been used as a test problem. Several curves of codimension-one bifurcations, and the boundaries of an Arnold's tongue of rotation number 1/8, have been computed.
Journal of Computational Physics, 2016
The viability of using collocation methods in radius and spherical harmonics in the angular varia... more The viability of using collocation methods in radius and spherical harmonics in the angular variables to calculate convective flows in full spherical geometry is examined. As a test problem the stability of the conductive state of a self-gravitating fluid sphere subject to rotation and internal heating is considered. A study of the behavior of different radial meshes previously used by several authors in polar coordinates, including or not the origin, is first performed. The presence of spurious modes due to the treatment of the singularity at the origin, to the spherical harmonics truncation, and to the initialization of the eigenvalue solver is shown, and ways to eliminate them are presented. Finally, to show the usefulness of the method, the neutral stability curves at very high Taylor and moderate and small Prandtl numbers are calculated and shown.
SIAM Journal on Applied Dynamical Systems, 2015
A five-degree model, which reproduces faithfully the sequence of bifurcations and the type of sol... more A five-degree model, which reproduces faithfully the sequence of bifurcations and the type of solutions found through numerical simulations of the three-dimensional Boussinesq thermal convection equations in rotating spherical shells with fixed azimuthal symmetry, is derived. A low Prandtl number fluid of σ = 0.1 subject to radial gravity, filling a shell of radius ratio η = 0.35, differentially heated, and with non-slip boundary conditions, is considered. Periodic, quasi-periodic, and temporal chaotic flows are obtained for a moderately small Ekman number, E = 10 −4 , and at supercritical Rayleigh numbers of order Ra ∼ O(2Rac). The solutions are classified by means of frequency analysis and Poincaré sections. Resonant phase locking on the quasi-periodic branches, as well as a sequence of period doubling bifurcations, are also detected.
Agronomy
The expansion of irrigated almond orchards in arid and semi-arid areas with scarce water availabl... more The expansion of irrigated almond orchards in arid and semi-arid areas with scarce water available raises key issues related to the sustainability of the water resources. A 3-year field experiment was conducted on a commercial young almond orchard located in the southeast of Spain to study the effect of two drip irrigation systems (surface, DI and subsurface, SDI) on almond crop growth and their physiological responses under fully-irrigated conditions. Crop evapotranspiration (ETc) and its components (crop transpiration, Tc and soil evaporation, Es) were monitored as well as the irrigation water and nitrogen productivities. To estimate ETc, a simplified two-source energy balance (STSEB) approach was used. Although a lower irrigation water amount was applied in SDI compared to DI (differences between 10% and 13.8%), the almond crop growth and physiological responses as well as the yield components and kernel yield showed no significant differences. The ETc estimates resulted in small...
Remote Sensing
Almost fifty years have passed since the idea to retrieve a value for Evapotranspiration (ET) usi... more Almost fifty years have passed since the idea to retrieve a value for Evapotranspiration (ET) using remote sensing techniques was first considered. Numerous ET models have been proposed, validated and improved along these five decades, as the satellites and sensors onboard were enhanced. This study reviews most of the efforts in the progress towards providing a trustworthy value of ET by means of thermal remote sensing data. It starts with an in-depth reflection of the surface energy balance concept and of each of its terms, followed by the description of the approaches taken by remote sensing models to estimate ET from it in the last thirty years. This work also includes a chronological review of the modifications suggested by several researchers, as well as representative validations studies of such ET models. Present limitations of ET estimated with remote sensors onboard orbiting satellites, as well as at surface level, are raised. Current trends to face such limitations and a f...
Water
Encouraged by the necessity to better understand the water use in this woody crop, a study was ca... more Encouraged by the necessity to better understand the water use in this woody crop, a study was carried out in a commercial drip-irrigated young almond orchard to quantify and monitor the crop evapotranspiration (ETc) and its partitioning into tree canopy transpiration (T) and soil evaporation (E), to list and analyze single and dual crop coefficients, and to extract relationships between them and the vegetation fractional cover (fc) and remote-sensing-derived vegetation indices (VIs). A Simplified Two-Source Energy Balance (STSEB) model was applied, and the results were compared to ground measurements from a flux tower. This study comprises three consecutive growing seasons from 2017 to 2019, corresponding to Years 2 to 4 after planting. Uncertainties lower than 50 W m−2 were obtained for all terms of the energy balance equation on an instantaneous scale, with average estimation errors of 0.06 mm h−1 and 0.6 mm d−1, for hourly and daily ETc, respectively. Water use for our young alm...
Remote Sensing
Monitoring Land Surface Temperature (LST) from Landsat satellites has been shown to be effective ... more Monitoring Land Surface Temperature (LST) from Landsat satellites has been shown to be effective in the estimation of crop water needs and modeling water use efficiency. Accurate LST estimation becomes critical in semiarid areas under water scarcity scenarios. This work shows the assessment of some well-known Single-Channel (SC) and Split-Window (SW) algorithms, adapted to Landsat 8/TIRS, under the conditions of a high-contrast semiarid agroecosystem. The recently released Landsat 8 Level-2 LST product (L8_ST) has also been included in the performance analysis. Ground measurements of surface temperature were taken for the evaluation during the summers of 2018–2019 in the cropland area of the Barrax test site, Spain. A dataset of 44 ground samples and 11 different L8/TIRS dates/scenes was gathered, covering a variety of crop fields and surface conditions. In addition, a simplified Single Band Atmospheric Correction (L-SBAC) was introduced based on a linearization of the atmospheric c...
Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requireme... more Estimates of surface actual evapotranspiration (ET) can assist in predicting crop water requirements. An alternative to the traditional crop-coefficient methods are the energy balance models. The objective of this research was to show how surface temperature observations can be used, together with a two-source energy balance model, to determine crop water use throughout the different phenological stages of a crop grown. Radiometric temperatures were collected in a sorghum (Sorghum bicolor) field as part of an experimental campaign carried out in Barrax, Spain, during the 2010 summer growing season. Performance of the Simplified Two-Source Energy Balance (STSEB) model was evaluated by comparison of estimated ET with values measured on a weighing lysimeter. Errors of ±0.14 mm h −1 and ±1.0 mm d −1 were obtained at hourly and daily scales, respectively. Total accumulated crop water use during the campaign was underestimated by 5 %. It is then shown that thermal radiometry can provide precise crop water necessities and is a promising tool for irrigation management. 1 Introduction Understanding the surface actual evapotranspiration (ET) is essential for managers responsible for planning and managing water resources, especially in arid and semi-arid regions where crop water demand generally exceeds precipitation and irrigation from surface and/or groundwater resources is then required to meet the deficit. This is particularly important in areas where water usage is regulated due
Forest fires are one of the most dangerous natural hazards, especially when they are recurrent. I... more Forest fires are one of the most dangerous natural hazards, especially when they are recurrent. In areas such as Galicia (Spain), forest fires are frequent and devastating. The development of fire risk models becomes a very important prevention task for these regions. Vegetation and moisture indices can be used to monitor vegetation status; however, the different indices may perform differently depending on the vegetation species. Eight different spectral indices were selected to determine the most appropriate index in Galicia. This study was extended to the adjacent region of Asturias. Six years of MODIS (Moderate Resolution Imaging Spectroradiometer) images, together with ground fire data in a 10 × 10 km grid basis were used. The percentage of fire events met the variations suffered by some of the spectral indices, following a linear regression in both Galicia and Asturias. The Enhanced Vegetation Index (EVI) was the index leading to the best results. Based on these results, a simple fire danger model was established, using logistic regression, by combining the EVI variation with other variables, such as fire history in each cell and period of the year. A seventy percent overall concordance was obtained between estimated and observed fire frequency.
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2021
Quantifying spatial and temporal patterns of the actual evapotranspiration (ET) using Earth obser... more Quantifying spatial and temporal patterns of the actual evapotranspiration (ET) using Earth observation data can significantly contribute to the accurate and transparent monitoring of sustainable development goals (SDGs) target 6.4, which focuses on the increase of the water-use efficiency and sustainable freshwater withdrawals. Irrigated agriculture is by far the largest consumer of freshwater worldwide, and ET can serve as a direct proxy of crop water use. Various ongoing initiatives encourage the use of remote sensing data for the monitoring of SDG 6.4, including the WaPOR portal run by the Food and Agriculture Organization of the United Nations. However, none of these initiatives use Copernicus satellite and modeled data to the fullest extent. Copernicus provides operational high-quality data freely and openly, contains all the inputs required for ET modeling, and has long-term continuity and evolution plans, thus allowing for the establishment of baseline for SDG 6.4 and continuous monitoring in mid-and long term. In this study, we evaluate the utility of Copernicus data for this task with WaPOR products serving as a comparison benchmark. Thus, the modeled ET has to be able to accurately capture the field-scale activity at 10-day timesteps while also scaling to national coverage and providing consistent estimates at different spatial resolutions, ranging from tens to hundreds of meters. Results indicate that
Wheat is one of the crops occupying the largest areas in the world (218 million ha in 2013). Unde... more Wheat is one of the crops occupying the largest areas in the world (218 million ha in 2013). Understanding the land-atmosphere energy exchanges over these croplands becomes important not only for agronomy but also for climatic and meteorological aspects. This study continues previous work on the estimation of actual evapotranspiration and the assessment of crop coefficients of sorghum, sunflower, or canola. Two variations of a simple two-source energy balance (STSEB) approach were used in combination with land surface temperature measurements to calculate hourly and daily values of surface fluxes and actual evapotranspiration (ET). An experiment was carried out during the spring season of 2014 in Las Tiesas experimental farm in Barrax, Spain. Soil and canopy temperature components together with meteorological variables and biophysical parameters were measured from planting to senescence. Comparison to lysimeter measurements showed calculation errors of ±0.11 mm h-1 and ±0.8 mm d-1 for hourly and daily ET values, respectively, whereas an underestimation no greater than 4% resulted from the entire campaign. Partition between soil and canopy components yielded a ratio of evaporation (E) to transpiration (T) of 36% to 64%, respectively, for the total growing season. Dual crop coefficients were also calculated and compared to those proposed by FAO56. Although separate E and T measurements were not available, similar results between the STSEB and FAO 56 models demonstrate the utility of the STSEB for investigating management strategies aimed at increasing crop water use efficiency.
Remote. Sens., 2021
The combination of the state-of-the-art in the thermal infrared (TIR) domain [...]
Past and present of the Spanish folletín novel The optimal conditions for the creation of a popul... more Past and present of the Spanish folletín novel The optimal conditions for the creation of a popular novel occurred in the 19 th century. With the influence, first of all, of French literature, there was in Spain a huge production of these works, known in Spanish as 'folletines' or folletín novel. Its importance for the study of literature is undeniable. It is possible to detect its legacy in the best Spanish novel between 1870 and 1936, for instance in Benito Pérez Galdós or Pío Baroja. But it is also interesting to compare this folletín novel with the modern bestseller. Similar techniques and conception of what should be a novel are to find in modern bestseller Spanish writers such as Carlos Zafón, Eduardo Mendoza or Arturo Pérez-Reverte. In this article, they are compared with the famous 'folletinistas' of the second half of the 19 th century: Manuel
Remote Sensing, 2021
This work aims to validate the wide use of an algorithm developed using genetic programing (GP) t... more This work aims to validate the wide use of an algorithm developed using genetic programing (GP) techniques allowing to discern between water and non-water pixels using the near infrared band and different thresholds. A total of 34 wetlands and shallow lakes of 18 ecological types were used for validation. These include marshes, salt ponds, and saline and freshwater, temporary and permanent shallow lakes. Furthermore, based on the spectral matching between Landsat and Sentinel-2 sensors, this methodology was applied to Sentinel-2 imagery, improving the spatial and temporal resolution. When compared to other techniques, GP showed better accuracy (over 85% in most cases) and acceptable kappa values in the estimation of water pixels (κ ≥ 0.7) in 10 of the 18 assayed ecological types evaluated with Landsat-7 and Sentinel-2 imagery. The improvements were especially achieved for temporary lakes and wetlands, where existing algorithms were scarcely reliable. This shows that GP algorithms ap...
The Egyptian Journal of Remote Sensing and Space Science, 2020
The Pampas Region is a big plain of approximately 520,000 km 2 in Argentina. It is essential to e... more The Pampas Region is a big plain of approximately 520,000 km 2 in Argentina. It is essential to estimate evapotranspiration (ET) in this region since the primary productivity is directly linked to water availability. Information provided by satellite missions allows monitoring the spatial and temporal variability of ET. In the current study, we evaluated the version 006 of MOD16A2 product (MOD16A2.006) of Potential Evapotranspiration (ETp) and Actual Evapotranspiration (ETa) in Argentinian Pampas Region (APR). MOD16A2.006 product was compared with Crop Evapotranspiration (ETc), calculated with local measurements from the Oficina de Riesgo Agropecuario (ORA), and Crop Coefficient (Kc) data (function of Normalized Difference Vegetation Index (NDVI)) in seven stations in the APR from 2009 to 2018. We evaluated ETa at two temporal scales: accumulated values (mm) per growth stages (soybean crop), and 8-day accumulated values (mm8d À1). The results showed a systematic overestimation around 65% for ETp (MOD16A2.006) (found and eliminated by means of a linear function) and underestimation (in most stations) for ETa (MOD16A2.006) in accumulated values per growth stages. Respect to mm8d À1 , no systematic error was observed, but the relationship ETa (ORA) À ETa (MOD16A2.006) for soybean crop behaves similarly throughout APR.
Remote Sensing, 2020
Downscaling techniques offer a solution to the lack of high-resolution satellite Thermal InfraRed... more Downscaling techniques offer a solution to the lack of high-resolution satellite Thermal InfraRed (TIR) data and can bridge the gap until operational TIR missions accomplishing spatio-temporal requirements are available. These techniques are generally based on the Visible Near InfraRed (VNIR)-TIR variable relations at a coarse spatial resolution, and the assumption that the relationship between spectral bands is independent of the spatial resolution. In this work, we adopted a previous downscaling method and introduced some adjustments to the original formulation to improve the model performance. Maps of Land Surface Temperature (LST) with 10-m spatial resolution were obtained as output from the combination of MODIS/Sentinel-2 images. An experiment was conducted in an agricultural area located in the Barrax test site, Spain (39°03′35″ N, 2°06′ W), for the summer of 2018. Ground measurements of LST transects collocated with the MODIS overpasses were used for a robust local validation...
Revista Brasileira de Engenharia Agrícola e Ambiental, 2020
The estimate of the actual surface evapotranspiration (ET) contributes to quantifying the water n... more The estimate of the actual surface evapotranspiration (ET) contributes to quantifying the water needs of crops. An alternative to the use of lysimeter for an accurate estimation of water needs, which has proved to be of great value in recent years, is the use of remote sensing combined with models based on surface energy balance. There is wide variety of models that can be classified into two types: one-source models, such as the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) algorithm, or two-source models, such as the Simplified Two-Source Energy Balance (STSEB). The objective of this study was to analyze how METRIC and STSEB can be used to estimate ET, in comparison with the lysimeter data, for the different stages of development of the sorghum crop in Apodi, RN, Brazil. The accuracy of both models in the daily ET estimation for the semi-arid conditions of the experiment, with RMSE values of 0.8 and of 0.7 mm d-1 through METRIC and STSEB, res...
Slovo a smysl, 2019
SYNOPSIS Cervantes and Tolerance The treatment of the morisco theme in Don Quixote could be under... more SYNOPSIS Cervantes and Tolerance The treatment of the morisco theme in Don Quixote could be understood as an index-a proof-of the philosophical and spiritual differences between Cervantes and the official ideology of his time. In his discourse, Ricote (the morisco character in Don Quixote II, 1615) names the 'freedom of conscience', an important theme in European religious discourse of the 16 th and 17 th centuries. This article deals with the interpretation of that expression in the literary and ideological context of Cervantesʼ novel and Cervantesʼ world. It seems that the expression refers to the Peace of Augsburg, and it could be interpreted as an appeal for tolerance, in this case regarding the morisco question (the moriscos were banned in 1609, before the publication of the second volume of Don Quixote). Yet this is a problematic interpretation: in Spain, the expression was commonly associated with heresy. It is in this sense that Lope de Vega uses the expression. This in turn is what allows us to characterize Lope de Vegaʼs literary work as conservative and Cervantesʼ as liberal.
Remote Sensing, 2018
Monitoring Land Surface Temperature (LST) from satellite remote sensing requires an accurate corr... more Monitoring Land Surface Temperature (LST) from satellite remote sensing requires an accurate correction of the atmospheric effects. Although thermal remote sensing techniques have advanced significantly over the past few decades, to date, single-band pixel-by-pixel atmospheric correction of full thermal images is unsolved. In this work, we introduce a new Single-Band Atmospheric Correction (SBAC) tool that provides pixel-by-pixel atmospheric correction parameters regardless of the pixel size. The SBAC tool uses National Centers of Environmental Prediction (NCEP) profiles as inputs and, as a novelty, it also accounts for pixel elevation through a Digital Elevation Model (DEM). Application of SBAC to 19 Landsat 7-ETM+ scenes shows the potential of the proposed pixel-by-pixel atmospheric correction to capture terrain orography or atmospheric variability within the scene. LST estimation yields negligible bias and an RMSE of ±1.6 K for the full dataset. The Landsat Atmospheric Correction Tool (ACT) is also considered for comparison. SBAC-ACT LST deviations are analyzed in terms of distance to the image center, surface elevation, and spatial distribution of the atmospheric water content. Differences within 3 K are observed. These results give us the first insight of the potential of SBAC for the operational pixel-by-pixel atmospheric correction of full thermal images. The SBAC tool is expected to help users of satellite single-channel thermal sensors to improve their LST estimates due to its simplicity and robustness.
Hipogrifo. Revista de literatura y cultura del Siglo de Oro, 2019
Táto práce vznikla v rámce grantu PROGRES Q14: Krize racionality v moderním myšlení. (Este trabaj... more Táto práce vznikla v rámce grantu PROGRES Q14: Krize racionality v moderním myšlení. (Este trabajo ha surgido en el marco de proyecto de investigación PROGRES Q14: La crisis de la racionalidad en el pensamiento moderno).
SIAM Journal on Applied Dynamical Systems, 2015
A methodology to track bifurcations of periodic orbits in large-scale dissipative systems dependi... more A methodology to track bifurcations of periodic orbits in large-scale dissipative systems depending on two parameters is presented. It is based on the application of iterative Newton-Krylov techniques to extended systems. To evaluate the action of the Jacobian it is necessary to integrate variational equations up to second order. It is shown that this is possible by integrating systems of dimension at most four times that of the original equations. In order to check the robustness of the method, the thermal convection of a mixture of two fluids in a rectangular domain has been used as a test problem. Several curves of codimension-one bifurcations, and the boundaries of an Arnold's tongue of rotation number 1/8, have been computed.
Journal of Computational Physics, 2016
The viability of using collocation methods in radius and spherical harmonics in the angular varia... more The viability of using collocation methods in radius and spherical harmonics in the angular variables to calculate convective flows in full spherical geometry is examined. As a test problem the stability of the conductive state of a self-gravitating fluid sphere subject to rotation and internal heating is considered. A study of the behavior of different radial meshes previously used by several authors in polar coordinates, including or not the origin, is first performed. The presence of spurious modes due to the treatment of the singularity at the origin, to the spherical harmonics truncation, and to the initialization of the eigenvalue solver is shown, and ways to eliminate them are presented. Finally, to show the usefulness of the method, the neutral stability curves at very high Taylor and moderate and small Prandtl numbers are calculated and shown.
SIAM Journal on Applied Dynamical Systems, 2015
A five-degree model, which reproduces faithfully the sequence of bifurcations and the type of sol... more A five-degree model, which reproduces faithfully the sequence of bifurcations and the type of solutions found through numerical simulations of the three-dimensional Boussinesq thermal convection equations in rotating spherical shells with fixed azimuthal symmetry, is derived. A low Prandtl number fluid of σ = 0.1 subject to radial gravity, filling a shell of radius ratio η = 0.35, differentially heated, and with non-slip boundary conditions, is considered. Periodic, quasi-periodic, and temporal chaotic flows are obtained for a moderately small Ekman number, E = 10 −4 , and at supercritical Rayleigh numbers of order Ra ∼ O(2Rac). The solutions are classified by means of frequency analysis and Poincaré sections. Resonant phase locking on the quasi-periodic branches, as well as a sequence of period doubling bifurcations, are also detected.