Jesús Gardiol’s research while affiliated with University of Buenos Aires and other places

Soil water content models have huge applications from an agronomic point of view and they are usually used as a sub-model for weather and climate modelling. They are also useful tools for efficient water management irrigation practices. The aim of this investigation is to evaluate the performance of two different parameterizations of evapotranspiration when applied to a soil water balance model. Experimental data of a maize crop is used to evaluate model accuracy. The first methodology proposes a parallel resistance arrangement to represent the latent heat fluxes of the soil surface and the leaves in the canopy layer considering the leaf area index (LAI). The second methodology uses the parameterization proposed by the United Nations Food and Agriculture Organization (FAO), based on the crop coefficient (Kc) and the potential evapotranspiration obtained from the Penman–Monteith equation. The crop was divided into five plots with different irrigation systems according to their phenological stages. The model suitably predicts daily soil water content in five different irrigation systems. Predictions of soil water content using the LAI or Kc methodology tend to overestimate observations. In addition, the model has better predictions using the LAI methodology than the Kc methodology. The root mean square error and the determination coefficient were 0.059 and 0.92, respectively, with the LAI methodology and 0.063 and 0.87, respectively, using the Kc methodology. Copyright © 2010 Royal Meteorological Society

El objetivo de este trabajo es presentar un programa de balance de agua que considera ajustes locales y permite estimar los componentes del balance de agua para diferentes cultivos.

En este trabajo se analizan las tendencias de Eto, sus componentes radiativa y aerodinámica como, así también, las variables determinantes, temperaturas máxima y mínimas, el déficit de presión, la velocidad del viento y la heliofanía relativa

This study aims to characterise the main synoptic field patterns associated with the potential for recirculation of pollen. A recirculation index (R) was calculated in the area of Mar del Plata, Argentina. The daily development of sea–land breeze and the related monthly frequencies of wind directions were studied. The sea breeze was present for 36.2% of the time, with a mean lifetime of about 2 h in winter and 15–20 h in summer. Recirculation of the air had an annual frequency of around 7%, with a net transport from the city outskirts towards the sea, for 39.4% of the year, and a net inland transport frequency of 38.4%. The Rotated Principal Component Analysis (PCA) was applied to obtain synoptic field patterns associated with potential conditions for recirculation in the area. It was shown that low-pressure systems or troughs between 45° and 60°S (i.e. over the country, the South Pacific and/or the South Atlantic and two anticyclones located in the Atlantic or South Pacific Oceans) are the most common weather conditions associated with air recirculation in the coastal area of Buenos Aires province. A case study with high night pollen concentrations was also analysed. Copyright © 2007 Royal Meteorological Society

El objetivo este trabajo es caracterizar la evaporación de los suelos con aptitud agrícola del Partido de Balcarce a través de la lámina fácilmente evaporable (REW), la lámina máxima de agua evaporable (TEW) y la duración de la fase 1 de la evaporación (t).

En el presente trabajo se propone realizar este ajuste para los Kc de soja, siendo los objetivos específicos a) determinar los Kc de soja a partir de la relación entre la ETM medida a campo y la ET0 según Penman-Monteith, b) ajustar curvas de Kc en función de tiempo desde emergencia y fracción del total de la estación de crecimiento.

Accurate evapotranspiration estimation is required for water resources planning. In a humid temperate environment as in Balcarce, Argentina, the Penman Monteith model presents good performance. However, its use sometimes is not possible due to missing data or to difficulties to estiamte its variables, leading to the use of empirical methods. For this reason, a sensitivity analysis to identify the degree of accuracy required for a variable to be incorporated into a model can help to select it in order to achieve accurate evapotranspiration estimates. The objectives in this paper were: a) to evaluate the intra and interannual variability of reference evapotranspiration estimated by the Penman Monteith model at Balcarce, Argentina and b) to evaluate the relative sensitivity of the reference evapotranspiration to the main variables of the Penman Monteith model. Monthly mean values showed seasonal pattern with maximum occuring in January (4.9 mm d-1) and minimum in July (0.8 mm d-1). Contribution of radiation term was predominant, with mean values of 70% from October to March. Vapour pressure deficit was the variable with best correlation with aerodynamic term and total evapotranspiration. Reference evapotranspiration was most sensitive to net radiation (SRRN=0.89) than to the components of aerodynamic term, namely wind velocity and vapour pressure deficit (SRu=SRDPV=0.36). Sensitivity coefficients exhibited seasonal pattern associated to relative contribution of radiation and aerodynamic terms.

Two models to estimate sunflower actual evapotranspiration (ETR) according to water availability were calibrated. One of the models considers ETR equal to maximum evapotranspiration (ETM) when soil water is readily available. If soil is drying below a critical value (UC), it is assumed that ETR/ETM ratio is a linear function of the water depletion. The other one considers that ETR/ETM ratio is an exponential function of the water availability and includes a c constant, which require calibration. Soil water balances were calculated as: rainfall-ETR ± soil water depletion, using the proposed models. Ten levels of critical value (UC) and c constant were tested against observed soil water content and actual evapotranspiration values. Estimated data are compared with experimental data over 2004-2005 season growing. Best performance was obtained for 0.7 level of critical value and 0.3 for c constant of linear and exponential models, respectively.

Vapour pressure deficit calculation procedures based on temperature, temperature and relative humidity and saturation vapour pressure are evaluated. A method using the average of air temperature in saturation pressure and average relative humidity for actual vapour pressure is currently used at Balcarce (Arg.). Methods based on determination of daily average vapour saturation pressure at maximum and minimum temperatures give similar results for vapour pressure deficit and evapotranspiration. Intermediate performances are achieved with methods based on hourly temperature and relative humidity. Poor results are obtained with vapour pressure deficit that consider saturation vapour pressure at minimum as actual vapour pressure. Non-dimensional relative sensitivity coefficients ranges from 0,27 to 0,43.