Rubén D. Piacentini

Extreme solar total and UV irradiances due to cloud effect measured near the summer solstice at the high-altitude desertic plateau Puna of Atacama (Argentina)

Broadband data of solar total (300–3000nm) and ultraviolet (UV) (295–385nm) irradiances as far as spectrometric data measured near the Southern Hemisphere summer solstice at the high-altitude desertic plateau Puna of Atacama, Argentina, are presented. The simultaneous contributions of small solar zenith angle, high-altitude desertic intertropical region plus a cumulus cloud formation around the Suns angular position in the sky produced extreme high intensities. In particular, several measured total irradiances in a time interval of about one-and-a half hours near noon were higher than the extraterrestrial solar constant corrected for the actual Earth–Sun distance on these days (1412W/m2), reaching a maximum value of 1528W/m2 at 12:09 (Argentina local time, i.e. UT—3h) corresponding to a solar zenith angle of 16°. The highest UV irradiance measured was 69.5W/m2 at 13:29 (θz=2.4°). Mean percentage increases due to cloud effect of 6% for UV and 12% for total solar irradiances were estimated with respect to the situation of no-clouds near Sun. The mean UV over total irradiances percentage ratio was also determined giving 4.7% at the moment of cloud enhancement and 5% outside it, which shows that the UV component was also increased, but to a lesser extent. So situations with cumulus cloud formation in this region in relation to its biological and material degradation impacts must be taken into consideration. Photographs showing the particular configuration of the Sun—cumulus cloud system obtained at moments of very high solar intensities are also presented.

Sensitivity of Biologically Active UV Radiation to Stratospheric Ozone Changes: Effects of Action Spectrum Shape and Wavelength Range {

Abstract Biological action spectra are commonly used to assess health and ecosystem responses to increases in spectral ultraviolet (UV) irradiances resulting from stratospheric ozone (O3) reductions. For each action spectrum, a normalized sensitivity coefficient (the radiation amplification factor [RAF]) can be calculated as the relative increase in biologically active UV irradiance for a given relative decrease in the atmospheric O3 column amount. We use a detailed radiative transfer model to calculate the dependence of RAF on the O3 column amount and the solar zenith angle (and, therefore, implicitly on latitude and season) for several commonly used action spectra. A simple analytical model is used to interpret the results in terms of the semilogarithmic slope of the action spectra in the UV-B and UV-A wavelength ranges. We also show that RAF may be overestimated substantially if the UV-A portion of an action spectrum is significant but is neglected. This is illustrated using several idealized action spectra as well as published action spectra for plant responses to UV irradiation. Generally, if the portion of an action spectrum measured longward of ∼300 nm spans less than about two orders in magnitude in its sensitivity, significant errors in the estimated RAF may ensue, and the use of this action spectrum in O3-related studies can be compromised.

High-Up: A Remote Reservoir of Microbial Extremophiles in Central Andean Wetlands.

The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3700 m. Being isolated and hostile, these so-called “High-Altitude Andean Lakes” (HAAL) are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles) such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern—though quite imperfect—analogs of environments proxy for an earlier time in Earths history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure). Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e., DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.

UV index values and trends in Santiago, Chile (33.5°S) based on ground and satellite data

We report on the surface UV index (UVI) variations in Santiago (Chile) a city with high air pollution and complex surrounding topography. Ground-based UV measurements were continuously carried out between January 1995 and December 2011, by using a multi-channel filter radiometer (PUV-510). Ground-based measurements and satellite-derived data retrieved from the Total Ozone Mapping Spectrometer (TOMS), the Ozone Monitoring Instrument (OMI), and the Scanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY), were compared. We found that satellite-derived UVI products largely overestimate surface UVI. Our ground-based UVI measurements were significantly lower than TOMS-derived UVI data: (46.1±6.3)% (in the period 1997-2003), and OMI-derived UVI data: (47.0±6.3)% (in the period 2005-2007). Clear-sky SCIAMACHY-derived UVI were found to be also nearly systematically greater than ground-based UVI measurements in the period 2002-2011. An exceptionally long period of clear skies between December 2010 and January 2011 was used to test further satellite-derived UVI data; in the whole period, OMI and SCIAMACHY data were 53.1% and 38.3% greater than our ground-based measurements, respectively. These differences are presumably due to aerosol load associated with the local pollution and the complex topography surrounding Santiago. In addition, linear regression allowed us to estimate trends that we use for forecasting. Methodological details are provided below.

Intercomparison between ground based and TOMS/EP satellite southern hemisphere ozone data. New results

Abstract We present new results of the intercomparison between ozone total column data registered at the Southern Hemisphere with the World Meteorological Organization ground stations of the Southern Cone Ozone Project placed in Uruguay, Argentina and the Antarctic continent, with the Total Ozone Mapping Spectrometer (TOMS) instrument on board the Earth Probe satellite and with the Global Ozone Monitoring Experiment (GOME) instrument on board the Earth Remote Sensing (ERS-2) satellite. At least for the region and period considered, GOME/ERS-2 ozone data gives lower mean systematic relative difference (−1.4 3.2) % than TOMS/EP (4.8 2.7) % with respect to groundspectroradiometers. An analysis of possible causes for the large systematic difference in this last case has been considered: differences with respect to a similar instrument placed in another satellite both measuring the same geophysical variable at different orbits; difference with respect to GOME/ERS-2 satellite measurements in the entire region; possible influence on TOMS data of the difference in reflectivity at the high latitude ice (snow)-sea boundary.

SOLAR DRYING SIMULATION OF PRUNES ARRANGED IN THIN LAYERS

ABSTRACT Solar drying of prunes arranged in thin layers in a multi-shelf type drier is simulated. The weather conditions are those found during harvest in humid pampa region (hot-temperate and humid climate). A mathematical model based on Luikovs theory of drying and including an equation that describes the material shrinkage is employed. The airstream humidification is taken into account in order to analyse the influences of shelves spacing and drier length in the final product characteristics. It is found that the relative moisture content heterogeneity is a useful design criterion. The influence of weather conditions in the drying time and the drying capacity are evaluated.

The incidence of erythemal and UV solar irradiance over Buenos Aires, Argentina

Measurements are presented of UV solar irradiances at 305, 320, 340 and 380 nm and erythemal irradiance on clear-sky days in the city of Buenos Aires, Argentina. These values are compared with data calculated from a radiative atmospheric transfer model. Two quantities of major importance in this model are the ozone and aerosol atmospheric contents. Different values are assigned to them in order to estimate their relative importance in the solar UV irradiance reaching this geographical location. Complementary data on ozone profiles, obtained with the DIAL technique at the same location, are also presented. These spectral and erythemal irradiances are of importance in relation to the biological effects induced in humans by solar UV radiation.

Solar UVB and Plant Damage Irradiances for Different Argentinean Regions

We calculated the integrated UVB and plant damage irradiances for Argentina, a country in the Southern Hemisphere spread over a large latitudinal range. The irradiances were calculated for clear sky days using the Madronich code for the average conditions of the months corresponding to the summer and winter solstices and the fall and spring equinoxes. Ozone, aerosol and ground albedo typical for each region and for each period of the year have been considered. A comparison was made of the behavior of these irradiances at the different locations. A more pronounced time dependence of the plant damage irradiance was obtained because of the fact that the corresponding spectrum is largely concentrated at a small wavelength of the UVB interval. We established a correlation between both irradiances, which can be approximated by a quadratic function. Because the plant damage irradiance is a quantity that is not directly measured by instruments, we showed the utility of the correlation by determining this biological effectiveness from the integrated UVB irradiance measured at the Astronomical Observatory of Rosario, Argentina, on clear sky days of the year 2001, as a characteristic example of the midlatitude near–sea level location of a highly productive agricultural region, which can be extended to other regions of the world. The plant damage results are relative ones (as is the case for the erythemal irradiance). So, they can be used to determine the maximum/minimum and asymmetry ratios, to study the influence of atmospheric variables and to make comparisons with other geographical locations.

Characterization of the atmospheric aerosols in the Buenos Aires area using sun photometer measurements

An analysis of aerosols optical parameters is made using the sun photometer measurements taken at CEILAP in 2000. The sun photometer deployed in the Buenos Aires suburb is part of AERONET. Using the present data set, time series of key optical parameters such as the optical depth at 500 nm and Angstrom coefficient of the wavelength scaling law are derived. Clustering the observations by mean of a statistical analysis we can infer the pollution episodes in the Buenos Aires area. They can be either of local or regional origins, depending on the meteorological conditions prevailing over central Argentina.

The use of environmental sustainability criteria in industrial processes

In several Guest Editorials and earlier articles, the connection between climate change and industrial processes has been analyzed in detail. In this editorial, the connections between sustainability and industrial processes are briefly considered. First, we define the concept of sustainability. Its definition comes from biology: A process is sustainable when it is able to indefinitely produce at a pace, which does not deplete the resources used and it needs to function and does not produce more contaminants than it can be absorbed by its environment (adapted from Cavalcante). The United Nations introduced a definition of sustainable development in the well-known report entitled Our Common Future (or the Brundtland Report), published by the World Commission on Environment and Development in 1987. According to the report, sustainable development “meets the needs of the present without compromising the ability of the future generations to meet their own needs” (p. 16). The modern definition is more holistic: “Sustainability is the ability to achieve sustained economic prosperity over time, while protecting the natural systems of the planet and providing a high quality of life for people.” In addition to environmental sustainability, two other pillars are economic and societal sustainability. In the first case, the proposal is to develop green economy that takes into account the natural capital (plant, animal, soil, and water resources) and the well-being of workers and indeed humanity as a whole. With respect to social sustainability, the idea is to develop fair and ethical trade, to respect clients, to give the same opportunities to all persons, and, besides other possibilities, to contribute to the improvement of society, mainly that of developing countries who are more affected by global warming. The importance of these three pillars is demonstrated by the need to present to the members of a company (shareholders, etc.) and all of society each year a triple-point balance, not only economic but also environmental and social balances. A relevant reference is the Global Reporting Initiative (GRI), which provides a framework to empower sustainability in an enterprise, industry, or organization: “Sustainability reporting as promoted by GRI Standards is the practice of public reporting by organizations on their economic, environmental and social impacts.” In what follows, we will develop several criteria that need to be taken into account if sustainability is to be considered in an industrial project: . Define System boundary and flows. The system needs to be defined with care in order to include all the components, as well as energy, material, water, and communication flows. It must be pointed out that an improvement in the process will be reflected in an increase in efficiency but a decrease in intensity. These improvements normally will also produce reduction in economic costs. . Fix the ultimate objective. The way to arrive at the final fixed objective in efficiency and/or intensity (using, for example, total quality technique) must be clearly defined. . Establish continuous improvement steps in order to tend to new (and better) final objectives. . Eliminate (or at least reduce) contamination in all forms, especially greenhouse gases (GHGs) and black carbon that produce global warming. In industrial processes, this can be done mainly by replacing nonrenewable fossil fuels with renewable energy sources (e.g., solar, hydro, geothermal, biomass/biofuels, hydrogen, compressed-air). . Determine the carbon inventory of the industry and the carbon footprint of a given product/equipment (see, for example, the Green Production Guide, the National Energy Foundation’s carbon calculator, and the Carbon Solutions’ calculator). In particular, there are International Organization for Standardization (ISO) norms in this respect (series 9000 on quality management, 14000 on environmental management, and 50000 on energy efficiency management) that need to be considered in order to take into account sustainability criteria at all levels. In particular, ISO reports that if the 50000 series norm could be applied all over the world, about 60% of the total energy used could be saved.