Browsing by Autor "Ricardo Forno"

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A decade of atmospheric composition observations in the undersampled Central Andes
(2022) Marcos Andrade; Diego Aliaga; Luis Blacutt; Ricardo Forno; René Gutierrez; Fernando Velarde; Isabel Moreno; Laura Ticona; Alfred Wiedensohler; Radovan Krejčí
&lt;p&gt;Ten years of almost continuous observations at the highest Global Atmosphere Watch Regional station in the world are presented here. The Chacaltaya observatory (5240 m asl, 16.3&amp;#186;S, 68.1&amp;#186;W) was set up in December 2011. It is currently the only operational station characterizing optical and chemical properties of climate-relevant aerosol and gases in Bolivia and in a radius of about 1500 kilometers from the station. The observations show a clear influence of the well-marked dry and wet meteorological seasons. In addition, the impact on the Andean mountains of long and mid-range transport of biomass burning products from the lowlands is clearly recorded in different parameters measured at the station. Furthermore, the nearby presence of the largest metropolitan area in the region (~1.8 million inhabitants) is observed almost on a daily basis, and therefore different campaigns were carried out to characterize the area and its influence on our measurements. Specific results from these campaigns are discussed elsewhere. Finally, the topographic complexity represents an important challenge for modeling efforts in order to understand sources and sinks (and associated processes) of the observed parameters, requiring not only high spatial resolution and the correct choice of model options, but a novel way of interpreting these results. The decade of collaboration of an international consortium made it possible to keep the station running successfully. The challenge is now to preserve its functioning for the coming decades in a region with historically few high-quality observations while disrupting environmental and socio-economic changes take place.&lt;/p&gt;
Black carbon emission and transport mechanisms to the free troposphere at the La Paz/El Alto (Bolivia) metropolitan area based on the Day of Census (2012)
(European Organization for Nuclear Research, 2018) A. Wiedensohler; Manuel Olivera Andrade; Kay Weinhold; Thomas Müller; W. Birmili; Fernando Velarde; Isabel Moreno; Ricardo Forno; Maria Fernanda Sanchez Barrero; Paolo Laj
Urban development, growing industrialization, and increasing demand for mobility have led to elevated levels of air pollution in many large cities in Latin America, where air quality standards and WHO guidelines are frequently exceeded. The conurbation of the metropolitan area of La Paz/El Alto is one of the fastest growing urban settlements in South America with the particularity of being located in a very complex terrain at a high altitude. As many large cities or metropolitan areas, the metropolitan area of La Paz/El Alto and the Altiplano region are facing air quality deterioration. Long-term measurement data of the equivalent black carbon (eBC) mass concentrations and particle number size distributions (PNSD) from the Global Atmosphere Watch Observatory Chacaltaya (CHC; 5240m a.s.l., above sea level) indicated a systematic transport of particle matter from the metropolitan area of La Paz/El Alto to this high altitude station and subsequently to the lower free troposphere. To better understand the sources and the transport mechanisms, we conducted eBC and PNSDs measurements during an intensive campaign at two locations in the urban area of La Paz/El Alto from September to November 2012. While the airport of El Alto site (4040m a.s.l.) can be seen as representative of the urban and Altiplano background, the road site located in Central La Paz (3590m a.s.l.) is representative for heavy traffic-dominated conditions. Peaks of eBC mass concentrations up to 5 μgm−3 were observed at the El Alto background site in the early morning and evening, while minimum values were detected in the early afternoon, mainly due to thermal convection and change of the planetary boundary layer height. The traffic-related eBC mass concentrations at the road site reached maximum values of 10–20 μgm−3. A complete traffic ban on the specific Bolivian Day of Census (November 21, 2012) led to a decrease of eBC below 1 μgm−3 at the road site for the entire day. Compared to the day before and after, particle number concentrations decreased by a factor between 5 and 25 over the particle size range from 10 to 800 nm, while the submicrometer particle mass concentration dropped by approximately 80%. These results indicate that traffic is the dominating source of BC and particulate air pollution in the metropolitan area of La Paz/El Alto. In general, the diurnal cycle of eBC mass concentration at the Chacaltaya observatory is anti-correlated to the observations at the El Alto background site. This pattern indicates that the traffic-related particulate matter, including BC, is transported to higher altitudes with the developing of the boundary layer during daytime. The metropolitan area of La Paz/El Alto seems to be a significant source for BC of the regional lower free troposphere. From there, BC can be transported over long distances and exert impact on climate and composition of remote southern hemisphere.
Black carbon emission and transport mechanisms to the free troposphere at the La Paz/El Alto (Bolivia) metropolitan area based on the Day of Census (2012)
(Elsevier BV, 2018) Alfred Wiedensohler; Marcos Andrade; Kay Weinhold; Thomas Müller; W. Birmili; Fernando Velarde; Isabel Moreno; Ricardo Forno; Maria Fernanda Sanchez Barrero; Paolo Laj
Urban development, growing industrialization, and increasing demand for mobility have led to elevated levels of air pollution in many large cities in Latin America, where air quality standards and WHO guidelines are frequently exceeded. The conurbation of the metropolitan area of La Paz/El Alto is one of the fastest growing urban settlements in South America with the particularity of being located in a very complex terrain at a high altitude. As many large cities or metropolitan areas, the metropolitan area of La Paz/El Alto and the Altiplano region are facing air quality deterioration. Long-term measurement data of the equivalent black carbon (eBC) mass concentrations and particle number size distributions (PNSD) from the Global Atmosphere Watch Observatory Chacaltaya (CHC; 5240 m a.s.l., above sea level) indicated a systematic transport of particle matter from the metropolitan area of La Paz/El Alto to this high altitude station and subsequently to the lower free troposphere. To better understand the sources and the transport mechanisms, we conducted eBC and PNSDs measurements during an intensive campaign at two locations in the urban area of La Paz/El Alto from September to November 2012. While the airport of El Alto site (4040 m a.s.l.) can be seen as representative of the urban and Altiplano background, the road site located in Central La Paz (3590 m a.s.l.) is representative for heavy traffic-dominated conditions. Peaks of eBC mass concentrations up to 5 μg m−3 were observed at the El Alto background site in the early morning and evening, while minimum values were detected in the early afternoon, mainly due to thermal convection and change of the planetary boundary layer height. The traffic-related eBC mass concentrations at the road site reached maximum values of 10–20 μg m−3. A complete traffic ban on the specific Bolivian Day of Census (November 21, 2012) led to a decrease of eBC below 1 μg m−3 at the road site for the entire day. Compared to the day before and after, particle number concentrations decreased by a factor between 5 and 25 over the particle size range from 10 to 800 nm, while the submicrometer particle mass concentration dropped by approximately 80%. These results indicate that traffic is the dominating source of BC and particulate air pollution in the metropolitan area of La Paz/El Alto. In general, the diurnal cycle of eBC mass concentration at the Chacaltaya observatory is anti-correlated to the observations at the El Alto background site. This pattern indicates that the traffic-related particulate matter, including BC, is transported to higher altitudes with the developing of the boundary layer during daytime. The metropolitan area of La Paz/El Alto seems to be a significant source for BC of the regional lower free troposphere. From there, BC can be transported over long distances and exert impact on climate and composition of remote southern hemisphere.
Breakdown of a Nocturnal Inversion Measured with a Low-Cost Tethersonde System: A High School Student Experiment
(American Meteorological Society, 2022) David N. Whiteman; Kofi Boateng; Sara Harbison; Hadijat Oke; Audrey Rappaport; Monique Watson; Ayomiposi Ajayi; Oluwafisayo Okunuga; Ricardo Forno; Marcos Andrade
Abstract For the past 4 years, four different cohorts of students from the Science and Technology program at Eleanor Roosevelt High School in Greenbelt, Maryland, have performed their senior research projects at the Howard University Beltsville Research Campus in Beltsville, Maryland. The projects have focused generally on the testing and correction of low-cost sensors and development of instrumentation for use in profiling the lower atmosphere. Specifically, we have developed a low-cost tethersonde system and used it to carry aloft a low-cost instrument that measures particulate matter (PM) as well as a standard radiosonde measuring temperature, pressure, and relative humidity. The low-cost PM sensor was found to provide artificially high values of PM under conditions of elevated relative humidity, likely due to the presence of hygroscopic aerosols. Reference measurements of PM were used to develop a correction technique for the low-cost PM sensor. Profiling measurements of temperature and PM during the breakdown of a nocturnal inversion were performed using the tethersonde system on 30 August 2019. The evolution of temperature during the breakdown of the inversion was studied and compared with model forecasts. The attempt to measure PM during the tethersonde experiment was not successful, we believe, due to the packaging of the low-cost sensor. Future cohorts of students from Eleanor Roosevelt High School students will work on improving the instrumentation and measurements shown here as we continue the collaboration between the Howard University Beltsville Campus and the local school system.
CAMPAÑA DE MEDICIONES ATMOSFÉRICAS EN LOS ANDES BOLIVIANOS REALIZADA POR EQUIPO ESTUDIANTIL BOLIVIANO-ESTADOUNIDENSE
(2024) David N. Whiteman; Marcos Andrade; Ricardo Forno; MAMANI-PACO; BLACUTT; René Gutierrez; Decker Guzmán Zabalaga
A student-focused field measurement campaign was held in the vicinity of Mt. Chacaltaya in the Bolivian Andes near the city of La Paz on May 24, 2022. The campaign was part of a program funded by the US Department of State, the main goal of which was to foster cultural and scientific exchange among Bolivian and US students. As part of this exchange, a group of eight Bolivian and four U.S. students worked together to plan and execute measurements which focused on quantifying the flow of particulate matter from the city of La Paz toward the summit of Mt. Chacaltaya, where the world’s highest elevation Global Atmosphere Watch site is located. Measurements were performed at three locations along a canyon that leads toward the summit of Mt. Chacaltaya and is a natural pathway for city-generated pollutants to travel toward the GAW station. The measurements indicated the presence of regular, solarheating-generated, downslope/upslope wind flow that aids the movement of particles near the mountain surface. The development of convection during the afternoon regularly decreased the concentrations measured at the surface and thus complicated the interpretation of particle flows. A novel, low-cost tethersonde apparatus was developed by members of the Laboratory for Atmospheric Physics (LFA) at the Universidad Mayor de San Andres (UM- ´ SA). Use of this tethersonde permitted vertical profiles of winds, temperature, pressure and relative humidity to be acquired thus allowing the investigation of the vertical structure of the transition between downslope and upslope flow. Outside of the measurement campaign, the students engaged in cultural activities together to enjoy local Bolivian sites and get to know each other better. One of the goals of the experiment was to increase interest in the atmospheric sciences among UMSA students. The results of a post-campaign survey indicate that participation in this joint field campaign has increased the number of physics students participating in the activities of the LFA at UMSA
Efectos de la radiación ultravioleta sobre la quinua (Chenopodium quinoa Willd.)
(1997) Eduardo Palenque; Marcos Andrade; Juan Antonio González; Ricardo Forno; Valeria Lairana; Fernando E. Prado; Juan Carlos Salcedo; Sara Urcullo
Eight years of continuous measurements of atmospheric methane at a high-altitude South American GAW station
(2023) Marcos Andrade; Michel Ramonet; Laura Ticona; Olivier Lauremt; Paolo Laj; Fernando Velarde; Isabel Moreno; Rene Gutierrez; Ricardo Forno; Luis Blacutt
&lt;p&gt;Measurements of methane concentrations were made at the Chacaltaya GAW station (16.3&amp;#186;S, 68.1&amp;#186;W, 5240m a.s.l.) in the Andean Cordillera from 2015 to date. During this period two high-precision Picarro-CRDS analyzers were used at the station, regularly calibrated with internationally certified gases (WMO X2004A) via the LSCE primary scale. The site has a privileged location not only due to its altitude but also because air masses arriving from the near Altiplano (3 800 m a.s.l.), the Amazon (so-called low-lands), the Pacific Ocean, and the nearby metropolitan area of La Paz/El Alto (~2 million of inhabitants) can be sampled there.&amp;#160; The complex topography of the region represents a challenge for deconvoluting the origin of the air masses and therefore to understanding the sources and/or processes associated with the measurements made at Chacaltaya. Here we show some results based on re-analysis data as well as on high and medium - resolution back trajectories in order to identify the influence of different regions on the station. In addition, satellite products and satellite-derived databases, from TROPOMI and GFED4.1s and WAD2M are used to characterize and interpret daily, seasonal and interannual behavior of the methane concentrations observed in Chacaltaya. The influence of the local atmospheric planetary boundary layer is clearly seen in the measurements, especially in the late morning, but collocated measurements of other atmospheric components such as carbon monoxide or equivalent black carbon have proven that identifying free-tropospheric air masses is not an easy task. &amp;#160;The contributions of the largest human conglomerate of the region are also discussed in this context.&lt;/p&gt;
Erythemally weighted UV variations at two high‐altitude locations
(American Geophysical Union, 2003) Francesco Zaratti; Ricardo Forno; J. García Fuentes; Marcos Andrade
A field campaign, with the purpose of measuring the rate of integrated erythemally weighted ultraviolet radiation (UVR) with altitude, was carried out at two high‐altitude locations near La Paz, Bolivia. The horizontal distance between the two sites is 25 km and they differ in height by 2 km. Irradiance data were obtained only on clear days and were analyzed using three different methods: (1) by comparison of integrated erythemal solar UV irradiances (daily doses) at both locations; (2) by calculation of the slope of the plot of the irradiance at the higher location against the irradiance at the lower location at the same time; and (3) by the asymptotic ratio, based on Beer's law, of the irradiances. The results show that erythemally weighted UV irradiance increases with altitude at an approximate rate of 7% per kilometer. The experimental data were compared with the output of a well‐known radiative model for local conditions. A sensitivity study of the nonmeasured input parameters indicated that the modeled rates of increase are slightly lower than the measured ones. Even more, these rates are not very sensitive to reasonable variations of the unknown parameters.
Estudio de estabilidad del Brewer #110 y de desgaste de las lámparas de calibración portátiles
(2001) Ricardo Forno; Francesco Zaratti
Estudio sobre la detección de aflatoxina en la castaña (Bertholetia excelsa), mediante fluorescencia bajo luz ultravioleta
(2005) Ricardo Forno; Alfonso Velarde
Evidence for Interhemispheric Mercury Exchange in the Pacific Ocean Upper Troposphere
(Wiley, 2022) Alkuin Maximilian Koenig; Jeroen E. Sonke; Olivier Magand; Marcos Andrade; Isabel Moreno; Fernando Velarde; Ricardo Forno; René Gutierrez; Luis Blacutt; Paolo Laj
Abstract Even though anthropogenic mercury (Hg) emissions to the atmosphere are ∼2.5 times higher in the Northern Hemisphere (NH) than in the Southern Hemisphere (SH), atmospheric Hg concentrations in the NH are only ∼1.5 times higher than in the SH. Global Hg models attribute this apparent discrepancy to large SH oceanic Hg emissions or to interhemispheric exchange of Hg through the atmosphere. However, no observational data set exists to serve as a benchmark to validate whether these coarse‐resolution models adequately represent the complex dynamics of interhemispheric Hg exchange. During the 2015–2016 El Niño, we observed at mount Chacaltaya in the tropical Andes a ∼50% increase in ambient Hg compared to the year before, coinciding with a shift in synoptic transport pathways. Using this event as a case study, we investigate the impact of interhemispheric exchange on atmospheric Hg in tropical South America. We use HYSPLIT to link Hg observations to long‐range transport and find that the observed Hg increase relates strongly to air masses from the tropical Pacific upper troposphere (UT), a region directly impacted by interhemispheric exchange. Inclusion of the modeled seasonality of interhemispheric air mass exchange strengthens this relationship significantly. We estimate that interhemispheric exchange drives Hg seasonality in the SH tropical Pacific UT, with strongly enhanced Hg between July and October. We validate this seasonality with previously published aircraft Hg observations. Our results suggest that the transport of NH‐influenced air masses to tropical South America via the Pacific UT occurs regularly but became more detectable at Chacaltaya in 2015–2016 because of a westward shift in air mass origin.
Intense transport of smoke to the Central Andes: Insights from a unique set of instruments located in the Bolivian Andean Cordillera
(2025) Marcos Andrade; Laura Ticona; Fernando Velarde; Decker Guzman; Luis Blacutt; Ricardo Forno; Rene Gutierrez; Isabel Moreno; Fernand Avila; Gaëlle Uzu
In 2024, Bolivia experienced the worst year of fires since 2002, when Aqua MODIS began collecting data. According to estimates, more than 15 million hectares were burned this year. A sunphotometer sitting in the Bolivian lowlands recorded AOD values higher than two for several continuous days indicating the degradation of the air quality in the region. A unique set of instruments located in the Bolivian Andes recorded the transport of smoke produced by this biomass burning. Very high values of atmospheric tracers like carbon monoxide, equivalent black carbon, and others have been measured as high as 5240 m asl&#160; at the Chacaltaya GAW station (CHC, 16.35&#186;S, 68.13&#186;W, 5240 m asl) and other sites around it both in the Altiplano and adjacent high altitude valleys. Although transport to these sites was observed previously, usually the events lasted one or two days. However, in 2024 longer periods of consecutive days with smoke arriving from the lowlands were observed for a second year in a row. Similar high values were observed in CHC in October of 2023, a year with less than half of fires in the country. The conditions that led to the transport of smoke to the mountains in the Andean Cordillera will be discussed, as well as the possible effects of the associated deforestation in terms of water availability for the central Andes.
LALINET: The First Latin American–Born Regional Atmospheric Observational Network
(American Meteorological Society, 2016) Juan Carlos Antuña; Eduardo Landulfo; René Estevan; Boris Barja; Alan Robock; Elián Wolfram; P. Ristori; B. R. Clemesha; Francesco Zaratti; Ricardo Forno
Abstract Sustained and coordinated efforts of lidar teams in Latin America at the beginning of the twenty-first century have built the Latin American Lidar Network (LALINET), the only observational network in Latin America created by the agreement and commitment of Latin American scientists. They worked with limited funding but an abundance of enthusiasm and commitment toward their joint goal. Before LALINET, there were a few pioneering lidar stations operating in Latin America, described briefly here. Biannual Latin American lidar workshops, held from 2001 to the present, supported both the development of the regional lidar community and LALINET. At those meetings, lidar researchers from Latin America met to conduct regular scientific and technical exchanges among themselves and with experts from the rest of the world. Regional and international scientific cooperation has played an important role in the development of both the individual teams and the network. The current LALINET status and activities are described, emphasizing the processes of standardization of the measurements, methodologies, calibration protocols, and retrieval algorithms. Failures and successes achieved in the buildup of LALINET are presented. In addition, the first LALINET joint measurement campaign and a set of aerosol extinction profile measurements obtained from the aerosol plume produced by the Calbuco volcano eruption on 22 April 2015 are described and discussed.
Latin American Lidar Network (LALINET) for aerosol research: Diagnosis on network instrumentation
(Elsevier BV, 2016) Juan Luís Guerrero-Rascado; Eduardo Landulfo; Juan Carlos Antuña; Henrique M. J. Barbosa; Boris Barja; Álvaro Bastidas; Andrés Esteban Bedoya-Velásquez; R. Costa; René Estevan; Ricardo Forno
Medidas de albedo en UV-b en el salar de Uyuni
(2010) Francesco Zaratti; Ricardo Forno; Gonzalo Gutiérrez; Roger Apaza; Fernando Velarde
Se reportan los resultados finales del proyecto bianual, centrado en dos campa ˜nas de medici ´on de la Radiaci´on Ultravioleta (RUV) en el Salar de Uyuni: la primera en mayo de 2008 y la otra en noviembre de 2008. Los datos recogidos en ambas campa ˜nas y el an´alisis respectivo han permitido llegar a importantes resultados en los dos objetivos principales del proyecto: medida del albedo superficial en la banda UV y cuantificaci ´on del alcance del mismo en la regi´on circundante al Salar. En el primer objetivo, se han encontrado indicios s´olidos de que el albedo depende no s´olo de la estaci´on del a ˜no, como se podr´ia esperar debido al r´egimen de lluvias localizado en los meses de enero a marzo, sino tambi´en de los cambios clim´aticos que se est ´an dando en la regi´on, lo que podr´ia conllevar una disminuci ´on del albedo, se ˜nal del “ensuciamiento” del Salar. Adicionalmente se ha medido el alcance de los efectos de albedo en el Salar, pero el an´alisis no muestra a ´un resultados concluyentes
MODELADO DE SOMBREROS
(2009) Ricardo Forno
Seis años de medidas de ozono y radiación ultravioleta en La Paz, Bolivia
(2003) Francesco Zaratti; Ricardo Forno; Pablo Saavedra; Lucy Cuarita
South American Aerosol Tracking - LALINET
(EDP Sciences, 2018) Eduardo Landulfo; Fábio Lopes; P. Ristori; Eduardo Quel; Lidia Otero; Ricardo Forno; Maria Fernanda Sanchez Barrero; Henrique M. J. Barbosa; Diego Alvés Gouveia; Amanda Vieira dos Santos
LALINET lidar stations were used to track down aerosols generated over Amazon region and transported over the continent. These data were merged with collocated Aeronet stations in order to help in their identification together with HYSPLIT simulations. The results show potential indication of how aerosol can age in their long transport over regions South and Westward from the source areas by change of their optical properties.
The Water Vapor Variability - Satellite/Sondes (WAVES) Field Campaigns
(2008) David N. Whiteman; Mariana Adam; C. Barnet; Bojan Bojkov; Rubén Delgado; Belay Demoz; J. Fitzgibbon; Ricardo Forno; R. L. Herman; Erik A. Hoff
Three NASA-funded field campaigns have been hosted at the Howard University Research Campus in Beltsville, MD. In each of the years 2006, 2007 and 2008, WAVES field campaigns have coordinated ozonesonde launches, lidar operations and other measurements with A-train satellite overpasses for the purposes of satellite validation. The unique mix of measurement systems, physical location and the interagency, international group of researchers and students has permitted other objectives, such as mesoscale meteorological studies, to be addressed as well. We review the goals and accomplishments of the three WAVES missions with the emphasis on the nonsatellite validation component of WAVES, as the satellite validation activities have been reported elsewhere.
Towards an instrumental harmonization in the framework of LALINET: dataset of technical specifications
(SPIE, 2014) Juan Luís Guerrero-Rascado; Eduardo Landulfo; Juan Carlos Antuña; Henrique M. J. Barbosa; Boris Barja; Álvaro Bastidas; Andrés Esteban Bedoya-Velásquez; R. Costa; René Estevan; Ricardo Forno
The Latin American Lidar Network (LALINET) is the aerosol lidar network operating over South America. LALINET is now an operative network performing a schedule of routine measurements and, currently, is composed by 9 stations distributed over South America. The main objective of LALINET is to generate a consistent and statistically relevant database to enhance the understanding of the particle distribution over the continent and its direct and indirect influence on climate. The creation of an un-biased spatiotemporal database requires a throughout review of the network on two pillars: instrumentation and data processing. Because most of the LALINET systems are not series-produced instruments and, therefore, present large differences in configuration and capabilities, attempts for network harmonization and, consequently, optimization are mandatory. In this study a review of the current instrumental status of all LALINET systems is done and analyzed in detail in order to assess the potential performance of the network and to detect networking weaknesses.