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The presence of pollen from Yungas tree species in fossil sequences located above the tree-line has led to alternative interpretations of past climate changes in tropical and subtropical Andes. We studied atmospheric and surface pollen deposition rates of Yungas trees along an altitudinal gradient (1700–3800 m a.s.l.) to understand the role of local wind patterns in modern pollen transport to mountain regions. Pollen from the Montane forest (Alnus and Juglans) and the Montane rainforest (Anadenanthera, Celtis and Myrtaceae) becomes airborne and is transported upslope well above the tree-line. The resulting patterns of pollen deposition show a secondary maximum in the Montane grassland, consistent with the development of a mountain-valley breeze system during the flowering period of the pollen producer species. Given that the pattern is also preserved in the surface sediment, we propose that these tree pollen types are good indicators of mesoscale atmospheric circulation and could provide a proxy for this circulation system in Quaternary records. This alternative approach to interpreting fossil pollen records of Yungas species in highlands of the Central Andes has implications for regional reconstructions of past climate. Fil: Torres, Gonzalo Román. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Unidad de Análisis Palinológicos. Laboratorio de Palinología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Perez, Claudio Fabian. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lupo, Liliana Concepcion. Universidad Nacional de Jujuy; Argentina. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Unidad de Análisis Palinológicos. Laboratorio de Palinología; Argentina

One of the most recommended method to estimate evapotranspiration (ET) of vegetated surfaces with different soil moisture conditions is the Penman-Monteith equation (PM). Canopy and soil conditions are parameterized through the surface resistance or conductance, while the contribution of the canopy to ET is measured by the canopy resistance. The study of natural ecosystems has gained interest because of its importance in water and carbon cycles. However, unlike monocultures, natural environments are composed of a mixture of species that make the estimation of ET with PM troublesome. This feature makes them suitable for ET estimation considering the contribution of both, the canopy and the soil represented by the surface resistance (rs), or the contribution of the canopy, represented by the canopy resistance (rc). This work aims to model the surface and canopy resistances using conventional meteorological, biological and pedological variables observed at a salt marsh used for livestock production in Buenos Aires province, Argentina. Twelve models (M1 to M12) based on the net solar radiation (Rn), air temperature (Ta), air relative humidity (RH), surface wind velocity (U), dew point departure (Dp), aerodynamic resistance (ra), leaf area index (LAI) and volumetric soil water content (ϑs) were obtained using two different regression methodologies. Surface resistances during daytime were calculated inverting the PM equation with ET fluxes measured with the eddy covariance method. PM-derived rs varied between 20 and 1000 s m−1, with a median of 137 s m−1. From 1620 observations, 468 were used for model calibration while 1152 for model validation. M5 and M11 with Rn, RH, ra, LAI predictor variables were the best models with 80.8 s m−1 root mean square error, 0.51 determination coefficient, 0.69 and 0.65 index of agreement, respectively. The modelled resistances allowed the estimation of latent heat fluxes with a root mean quadratic error varying from 60.7 to 69.5 W m-2. These results show the possibility to achieve rs from a minimum set of variables easily measured in the field which in turn, allows to estimate the ET of salt marsh ecosystems with scarce meteorological information.

Introducción y objetivos: Las afecciones respiratorias, como el asma, la rinitis y las alergias, están aumentando en todo el mundo, en asociación a una mayor presencia en el aire de distintos agentes etiológicos desencadenantes, de los cuales, el polen es uno de los más importantes. Estas evidencias muestran la importancia de monitorear sus concentraciones con fines preventivos o de posible control. Este trabajo reporta la incidencia y prevalencia del contenido polínico de la atmósfera y los tipos alergénicos presentes en el aire de la ciudad de Sunchales (Santa Fe, Argentina) durante dos períodos de estudio (agosto-noviembre 2012, agosto-diciembre 2013) con el objetivo de presentar un relevamiento preliminar para la localidad.M&M: Las muestras se colectaron con una trampa Burkard ubicada a 1,3 m sobre el suelo con un volumen de aspiración de 0,6 m3 h-1. Se analizaron con microscopio óptico a 400x, recorriendo la totalidad del preparado. Así se determinó la concentración diaria (gr m-3) para los tipos polínicos reconocidos. El reconocimiento de los mismos y su alergenicidad se determinó mediante bibliografía especializada.Resultados & Conclusiones: En comparación con otras ciudades del país, el registro es rico en especies, aunque la concentración diaria para el período analizado es baja. La mayoría del polen capturado (cerca de 70%) corresponde a sólo cuatro tipos polínicos (Cupressaceae, Moraceae, Poaceae y Urticaceae) reportados en la bibliografía como alergénicos. Background and aims: Respiratory diseases, such as asthma, rhinitis and allergies, are increasing worldwide, in association with a greater presence of different etiological triggers in the air, from which pollen is one of the most important. These evidences show the importance of monitoring airborne pollen concentrations for preventive or possible control purposes. This paper reports the incidence and prevalence of airborne pollen content as well as the allergenic pollen types present in the air of Sunchales city (Santa Fe, Argentina) during two study periods (August - November 2012, August - December 2013) aiming to present a preliminary pollen monitoring for the city. M&M: The samples were collected with a Burkard trap located 1.3 m above the ground with a suction volume of 0.6 m3 h-1. The entire slide was analyzed with an optical microscope at 400x final magnification. The daily concentration (gr m-3) was determined for the recognized pollen types. Pollen recognition and their allergenicity were determined with specialized literature. Results & Conclusions: Compared to other cities in the country, species richness is high, although the daily concentration for the period analyzed is low. The majority of the captured pollen (about 70%) corresponds to only four pollen types (Cupressaceae, Moraceae, Poaceae and Urticaceae) reported in the literature as allergens. Fil: Perez, Claudio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Gassmann, María Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Ulke, Ana Graciela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Merino, Rodrigo Andres. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina

Salt marshes are vulnerable ecosystems since they are found in locations often preferred for urban development. They produce a great amount of biomass, and also are of great interest because of the ecosystem services they provide from which carbon storage stands out. This work aims to study the energy and mass exchanged by a salt marsh located in southeastern Buenos Aires province (Argentina) and to characterize its net ecosystem production. A field campaign was carried out from February 2014 to March 2015. Sensible heat, water vapor (H2O) and carbon dioxide (CO2) fluxes were measured with eddy covariance technique at 6 m height over a Spartina densiflora canopy. Fifty five percent of the data were lost and 15% more were discarded due to low turbulence conditions. This gaps were filled with a combination of techniques (look-up tables and mean diurnal variations), which allowed the estimation of monthly mean net ecosystem exchange, gross primary production and ecosystem respiration. As in other marshes, the latent heat flux consumed more than 55% of the available energy of the system, reaching up to 85% after a large flood event. This flux systematically exceeds the values of sensible heat measured throughout the study period. Unlike other environments, this southern salt marsh behaved as a CO2 sink throughout the year. The net ecosystem production from March 2014 to February 2015 was approximately −10.5 t of CO2 ha−1 yr−1 which is greater than reported results for other wetlands. These preliminary results for a southern S. densiflora salt marsh are encouraging, although new field studies are under way to confirm their accuracy.

Accumulated pollen sequences are used to infer temporal changes in vegetation composition. Pollen transport and dispersal by winds introduce large biases in the interpretation of pollen records. In order to calibrate the models used to infer past species distributions, human activities or climate, contemporary time series of pollen records are assessed and modelled. The Gaussian plume model assumes that pollen transport takes place in a neutral atmosphere and pollen contribution is even from all directions (isotropy). In this study, we analyse these assumptions with airborne pollen measurements of Weinmannia trichosperma, a forest tree which grows mainly on the western slopes of the Andes, along with other characteristic species of the steppe which develops in eastern Patagonia. Instead of the Gaussian plume mixing model that is usually employed in the theory of pollen analysis, we apply a full 3D Lagrangian dispersion model, which allows calculation of potential source distributions (footprint) from modelled backward trajectories of airborne pollen observations. Results show that neutral atmospheric conditions are properly assumed for the region. The footprint calculated from the modelled trajectories of a five-year record is consistent with the location of pollen sources but the footprint shape showed that pollen contribution is uneven due to the influence of transient weather systems. Fil: Perez, Claudio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Bianchi, Maria Martha. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Secretaría de Cultura de la Nación. Dirección Nacional de Cultura y Museos. Instituto Nacional de Antropología y Pensamiento Latinoamericano; Argentina Fil: Gassmann, María Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Tonti, Natalia Edith. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Pisso, Ignacio. Norwegian Institute for Air Research; Noruega

Recent airborne pollen records data from Northern Patagonia (San Carlos de Bariloche, Argentina, Lat. 41.1435° S, Long. 71.375° W, 800 m elevation) suggest that pollen transport takes place from the west to the east slope of the Andes. However, the atmospheric characteristics responsible of this transport have not yet been studied. The aim of this paper is to assess potential source areas and to describe the involved atmospheric mechanisms of the trans-Andean pollen transport. Methodology relies on the analysis of backward trajectories of air masses calculated with the HYSPLIT 4.9 regional model for particular days where airborne pollen of Weinmannia trichosperma Cav. was detected east of the Andes. This pollen type was selected because it is found regularly at localities in eastern Patagonia beyond its present-day distribution. Weinmannia's substantial presence during early Holocene times would also benefit from better knowledge of its transport mechanisms. Correspondence between atmospheric trajectories and the position of sources was checked using GIS maps. Mode T, Principal Component Analysis (PCA) with Varimax rotation was used to identify the main spatial structure of geopotential height anomalies producing the calculated trajectories. Eighty-eight cases showed that the calculated directions of trajectories trended from the Northwest to Southwest passing over the Chilean region of W. trichosperma distribution. PCs results showed two patterns of negative anomalies over southern Patagonia. The prevailing circulation pattern which drives airborne transport is the presence of a trough located south of 37 to 40° S with its axis over western Patagonia. The synoptic situations for two cases highly correlated with principal component scores were described.

A statistical analysis was performed on a sample of 4 days sequences in which rainfall occurred during the second day, in order to establish airborne pollen–precipitation relationships. Drizzle (precipitation ≤ 1 mm) and rain (precipitation > 1 mm) events were considered as well as arboreal or non-arboreal pollen. Results showed that arboreal pollen decreases synchronically with the occurrence of a drizzle, registering the minimum value the following day of the precipitation occurrence. The high frequencies of fog and wet soil associated with the following day of drizzle occurrence support the hypothesis that besides the wash out, airborne pollen concentration could decrease by nucleation and impaction processes. As well, diurnal variation suggests that high humidity conditions could also affect pollen emission as already demonstrated by other authors.

Intradiurnal variation of arboreal pollen (AP) in Mar del Plata city is compared during three non - consecutive 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.

Intradiurnal variation of non-arboreal pollen (NAP) aredescribed in relation to the associated weather using the data obtainedwith a Burkard trap in Mar del Plata city, for a three year data set(1988, 1992 and 1995). The daily pattern of concentration was quitehomogeneous during the years analysed except for 1995, when it showed avariation due to the change of position of the station. Qualitativecomposition of the NAP airborne pollen was mainly represented byPoaceae, Plantago and Cyperaceae during the three years. The daily trendshowed high concentrations during daylight hours, when instability andconvective movements prevail, and low concentrations in the night, whenmeteorological conditions favour the development of a stable stratifiedlayer.

Continuous aerobiological survey of the atmosphere of Mar del Plata was carried out from December 1991 to November 1993 with a Burkard volumetric spore trap. Daily slides were prepared and studied every 2 h with standard techniques. Weekly records were kept for 27 relevant pollen types selected either by their prevalence or relative high atmospheric concentration. Quantitative multivariate analysis enabled to distinguish three major pollen seasons, related to atmospheric dominance either arboreal pollen (AP) or non-arboreal pollen (NAP). June to October is the richest period in number of pollen types, mainly dominated by AP; while from November to May, there is an overwhelming dominance of NAP types, represented by grass, herb and weed pollen. The study and prediction of this phenomenon is of great interest not only from the ecosystem point of view, but in relation to human disease as well.

A continuous aeropalynological survey of the atmosphere of Mar del Plata was carried out from December 1992 to November 1993 using a Burkard volumetric spore trap. Ten‐day averages were calculated for 28 relevant taxa, selected on the basis of their relative high concentration in the air. The total annual concentration (Cupressaceae pollen excluded) was 84,445 grains/m3, with 42% of total appearing during September and October. The pollen spectrum largely reflects urban anemopyilous vegetation, which is characterised by naturally occuring herbs and by ornamental shrub and tree species. A qualitative analysis shows two major pollen seasons related to the atmospheric dominance of either arboreal or non arboreal pollen.

A partir de observaciones micrometeorológicas se estudiaron los términos de la partición energética sobre un cultivo de soja. El desbalance observado, despreciando el calor acumulado por la cobertura vegetal, fue de 22% de la radiación neta. Durante el período completo de observaciones el 60% de la energía del sistema fue utilizada para evapotranspiración. On the basis of micrometeorological observations we explore the terms of the surface energy partition on a soybean crop. The imbalance energy, after rejecting the heat accumulated in the canopy, has a value of 22% of the net radiation. During the observational period a 60% of the available energy was used for evapotranspiration. Fil: Tonti, Natalia Edith. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Gassmann, María Isabel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Covi, Mauro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Perez, Claudio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina Fil: Righetti, Silvina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Ministerio de Defensa. Secretaria de Planeamiento. Servicio Meteorológico Nacional; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias de la Atmósfera y los Océanos; Argentina

Long range transport of airborne pollen has been seldom studied in South America. Backward trajectories of Celtis and Nothofagus pollen grains trapped over a meteorological station outside Mar del Plata City were calculated in one-hour steps using the regional hybrid model developed by the NOAA (HYSPLIT 4.5) and the data of the NCEP filed in the NOAA server. Results showed that the observed trajectories agree with the location of vegetation sources of the collected tree species. In the case of Celtis, the transport was associated to anticyclones located east of the city, generating winds with a N-NE component, which produce pollen cloud advection from the Celtis forests located some tens of kilometers to the N and NE of the city. The sources of Nothofagus pollen correspond to a narrow strip on the Andes slopes between 39 degrees and 55 degrees S, at least 1100 km to the SW of Mar del Plata. The transport was associated to eastward displacement of the troughs corresponding to the Westerlies circulation and the presence of an anticyclone system that brings back Nothofagus pollen towards Mar del Plata area.