Intradiurnal variation of arboreal pollen (AP) in Mar del Plata city is compared during three nonconsecutive years of survey and described in relation to the associated weather. The daily pattern of pollen abundance has a maximum between 10:00 and 12:00 h, while a minimum occurs at 18:00 h. The first two years of survey showed homogeneous daily trends, but in 1995 the maximum and minimum concentrations were delayed because of the change in position of the collecting station. Arboreal pollen spectrum presented qualitative and quantitative changes in the three years analysed. Results indicate optimal conditions for diurnal dispersion of arboreal pollen are high temperatures and low relative humidity. Also interaction between source position and wind direction has important effects on the timing of the peaks of some pollen types.
This paper presents a statistical study of the sea-land breeze in Mar del Plata (Argentina) to characterize the periods of the year when the breeze affects pollen transport, particularly the dispersion of airborne Poaceae pollen between urban and rural areas. In order to analyse the sea breeze circulation, hourly data from coastal, urban and rural meteorological stations were used. The effect of the sea breeze on the particulate matter was analysed from syncronic hourly airborne pollen records from an urban and a rural area. A sea-land breeze appeared between spring and early autumn in the hours of greatest diurnal warming. Results showed that the surface wind direction most probably associated with this phenomenon is NE and E, the time of occurrence shifting to new directions following the counterclockwise rotation, according to theoretical models for the Southern Hemisphere. Poaceae emission takes place in the morning, during the hours of maximum insolation. However, after the occurrence of the breeze, a rise in pollen concentration between 2000 hours and 0200 hours is detected because of pollen reentrainment brought about by air recirculation. The results showed that breeze transport brings a regional component to pollen assemblage.
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 (K c ) 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 K c methodology tend to overestimate observations. In addition, the model has better predictions using the LAI methodology than the K c 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 K c methodology.
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.
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