On December 14, 2020, southern South America experienced a total solar eclipse close to the solar noon. The path of totality, about 90 km wide, extended over the continental region from the Chilean west coast to the Argentine east coast, passing through the provinces of Neuquén, Río Negro and the extreme south of Buenos Aires. In order to study the effects on the atmosphere produced by the total eclipse, the Servicio Meteorológico Nacional Argentino (SMN) and Instituto de Investigaciones Científicas y Técnicas para la Defensa (CITEDEF) carried out a surface radiometric monitoring campaign in Valcheta (40.69°S; 66.15°W), Río Negro, Argentina. In this work, we explore the global surface solar irradiance on a horizontal plane (GHI) with the main objective of quantifying the changes in this parameter for cloudy and clear sky atmospheric conditions, combining ground-based measurements and modeling. A solar limb-darkening function was successfully implemented in the calculation of the irradiance at the top of the atmosphere (TOA) during the eclipse. We estimated a significant GHI attenuation of 41 % between the first (C1) and last (C4) contacts of eclipse compared to similar atmospheric conditions without the total eclipse, which represent a daily reduction of 12 %. In terms of irradiation, a reduction of 3360.1 KJ/m2 was calculated.

Total ozone column (TOC) measurements through the Ozone Monitoring Instrument (OMI/NASA EOSAura) are compared with ground-based observations made using Dobson and SAOZ instruments for the period 2004–2019 and 2008–02/2020, respectively. The OMI data were inverted using the Differential Optical Absorption Spectroscopy algorithm (overpass OMI-DOAS). The four ground-based sites used for the analysis are located in subpolar and subtropical latitudes spanning from 34°S to 54°S in the Southern Hemisphere, in the Argentine cities of Buenos Aires (34.58°S, 58.36°W; 25 m a.s.l.), Comodoro Rivadavia (45.86°S, 67.50°W; 46 m a.s.l.), Río Gallegos (51.60°S, 69.30°W; 72 m a.s.l.) and Ushuaia (54.80°S, 68.30°W; 14 m a.s.l.). The linear regression analyzes showed correlation values greater than 0.90 for all sites. The OMI measurements revealed an overestimation of less than 4 % with respect to the Dobson instruments, while the comparison with the SAOZ instrument presented a very low underestimation of less than 1 %.

El volcán chileno Puyehue – Cordón Caulle entró en erupción el día 4 de junio de 2011. La actividad eléctrica atmosférica relacionada con este fenómeno fue detectada en el CEILAP (CITEDEF-CONICET; 34,5º S; 58,5º O) por la red de Alerta Temprana de Volcanes perteneciente a la red mundial WWLLN (World Wide Lightning Location Network) a las 18.41 UTC. Las cenizas eyectadas fueron transportadas por los vientos alcanzando la provincia de Buenos Aires. Éstas fueron detectadas en el laboratorio el día 7 de junio con un sistema lidar coaxial multilongitud de onda. En este trabajo se analizan 100 horas de mediciones continuas efectuadas con el sistema lidar e información adicional y complementaria para estudiar en forma intensiva el evento como imágenes satelitales (AQUA y TERRA), retrotrayectorias (modelo HYSPLIT/NOAA), espesores ópticos de aerosoles (red AERONET administrada por NASA) y atenuación en el flujo de radiación solar (UV y visible) en Buenos Aires y evolución y evaluación de la actividad eléctrica atmosférica en torno al volcán.

In this paper we examined the annual variability of the erythemal solar radiation (a health risk) and the solar irradiance for synthesis of vitamin D (a health benefit) in Río Gallegos, Argentina. We use ultraviolet radiation measurements made by a multiband filter radiometer GUV-541 and a Brewer spectrophotometer located at CEILAP-RG Station (CITEFA-CONICET) (51° 33' S, 69° 19' W). These measurements are weighted with action spectra published by the CIE (International Commission on Illumination). An action spectrum describes the relative effectiveness of different wavelengths in the generation of a particular biological response. The analyzed data correspond to September 2008–December 2009 period.

With the aim of contribution to the study of atmospheric ozone layer, a new sensitive radiometer for atmospheric minor constituents has been installed in the Observatorio Atmosferico de la Patagonia Austral, Division LIDAR, CEILAP (CITEDEF-CONICET), in October 2010. This observatory is established in the city of Rio Gallegos (51 degrees 36' S, 69 degrees 19' W), Argentina, close to the spring ozone hole.The millimeter wave radiometer was developed in STEL (Solar Terrestrial Environment Laboratory), Nagoya University, Japan. This passive remote sensing instrument is able to measure the ozone (O-3) amount in the high stratosphere and mesosphere continuously and automatically with a high time resolution. The millimeter wave radiometer ozone profiles will be supplemented with the ozone profiles obtained from the DIAL system existent in the observatory. The millimeter wave radiometer is based on the spectral signal detection from the atmosphere due to the molecular rotational transition of molecules under study. The operation is based on a superheterodyne system which uses a Superconductor-Insulator-Superconductor (SIS) mixer receiver operating at 203.6GHz. The SIS mixer junction consists of a sandwich structure of Nb/AlOx/Nb, and is cooled to 4.2K with a closed cycle He-gas refrigerator. Two additional heterodyne-mixed stages are realized with the aim to shift the measured spectral line until a frequency around of 500 MHz. A FFT (Fast Fourier Transform) spectrometer system is used as a back end.The aims of this work are to show the potential of the millimeter wave radiometer installed in the subpolar latitudes close to the polar ozone hole and to present the preliminary result of the first measurements.

The ozone layer is regarded as an invisible filter that protects all life from the dangerous overexposure to ultraviolet rays. The thinning of the ozone layer over the South Pole stratosphere of our planet is a seasonal phenomenon that takes place every year during the spring since the 80s and is known as the “ozone hole”. It is developed on the Antarctic, reaching an area of 30 million square kilometers approximately. In the spring begins to deform reached lower latitudes, presenting specific cases of low total ozone column over Rio Gallegos (51 ° 36 'S, 69 º 19' W) due to the passage of the hole and its border over this city, which can derive in UV indices greater increasing the UV radiation impact on surface. This study evaluates the statistical dependence of the UV index with total ozone column and cloud optical thickness in the Patagonian city of Rio Gallegos for spring and summer. Another aim is to quantify the attenuation of UV radiation produced for the clouds to cases that the ozone hole is passing over the city. The cloud optical thickness and UV index data analyzed were obtained at Station CEILAP RG (CITEFA-CONICET) with a narrowband multichannel radiometer GUV-541 (Biospherical Inc.), and the total ozone column data were extracted from the Satellite OMI / AURA database of NASA. All these belong to the spring and summer seasons of the October 2005-December 2008 period. It is noted that 25% of ozone hole cases in springtime, which would result in a high UVI on Rio Gallegos, are strongly attenuated by the clouds.

La capa de ozono es considerada como un filtro invisible que protege toda forma de vida de la peligrosa sobreexposición a los rayos ultravioletas. El adelgazamiento de esta capa en la estratósfera del polo sur de nuestro planeta es un fenómeno estacional que desde la década de los '80 se desarrolla cada año durante la primavera y se conoce como "agujero de ozono". El mismo se desarrolla sobre la región Antártica alcanzando un área aproximada de 30 millones de kilómetros cuadrados en su máxima expresión. En primavera comienza a deformarse alcanzando latitudes menores, presentando casos puntuales de bajos niveles de columna total de ozono sobre Río Gallegos (51º 36’ S, 69º 19’ O) debido al paso del agujero y su borde sobre esta ciudad, lo que puede derivar en índices UV mayores aumentando el impacto de la radiación en superficie. En este estudio se evalúa la dependencia estadística del índice UV con la columna total de ozono y el espesor óptico de nubes, en la ciudad patagónica de Río Gallegos para primavera y verano. Además, se pretende cuantificar la atenuación de la radiación UV producida por las nubes para los casos en que el agujero de ozono sobrepasa dicha ciudad. Los datos de espesor óptico de nubes e índice UV analizados fueron obtenidos en la Estación CEILAP RG (CITEFA-CONICET) con un radiómetro multicanal de banda angosta GUV-541 (Biospherical Inc.) y los datos de columna total de ozono fueron extraídos de la base de datos del satélite OMI/AURA de la NASA. Todos estos corresponden a las estaciones de verano y primavera del período octubre de 2005–diciembre de 2008. Se observa que el 25% de los casos de agujero de ozono en primavera que derivarían en un IUV alto sobre Río Gallegos, son atenuados fuertemente por las nubes