Browsing by Autor "Isabel Moreno"

Now showing 1 - 20 of 44

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;
Air monitoring of new and legacy POPs in the Group of Latin America and Caribbean (GRULAC) region
(Elsevier BV, 2018) Cassandra Rauert; Tom Harner; Jasmin K. Schuster; Anita Eng; Gilberto Fillmann; Luisa E. Castillo; Oscar Fentanes; Martı́n Villa Ibarra; Karina S.B. Miglioranza; Isabel Moreno
Atmospheric Black Carbon in the metropolitan area of La Paz and El Alto, Bolivia: concentration levels and emission sources
(2024) Valeria Mardoñez-Balderrama; Griša Močnik; Marco Pandolfi; Robin L. Modini; Fernando Velarde; Laura Renzi; Angela Marinoni; Jean‐Luc Jaffrezo; Isabel Moreno; Diego Aliaga
Abstract. Black carbon (BC) is a major component of sub-micron particulate matter (PM) with significant health and climate impacts. Many cities in emerging countries lack comprehensive knowledge about BC emissions and exposure levels. This study investigates BC concentration levels, identify its emission sources, and characterize the optical properties of BC at urban background sites of the two largest high-altitude Bolivian cities: La Paz (LP) (3600 m above sea level) and El Alto (EA) (4050 m a.s.l.) where atmospheric oxygen levels and intense radiation may affect BC production. The study relies on concurrent measurements of equivalent black carbon (eBC), elemental carbon (EC), and refractory black carbon (rBC), and their comparison with analogous data collected at the nearby Global Atmosphere Watch-Chacaltaya station (5240 m a.s.l). The performance of two independent source-apportionment techniques was compared: a bilinear model and a least squares multilinear regression (MLR). Maximum eBC concentrations were observed during the local dry season (LP: eBC=1.5±1.6 μg m-3; EA: 1.9±2.0 μg m-3). While eBC concentrations are lower at the mountain station, daily transport from urban areas is evident. Average mass absorption cross sections of 6.6-8.2 m2 g-1 were found in the urban area at 637 nm. Both source apportionment methods exhibited a reasonable level of agreement in the contribution of biomass burning (BB) to absorption. The MLR method allowed the estimation of the contribution and the source-specific optical properties for multiple sources including open waste burning.
Atmospheric black carbon in the metropolitan area of La Paz and El Alto, Bolivia: concentration levels and emission sources
(Copernicus Publications, 2024) Valeria Mardoñez-Balderrama; Griša Močnik; Marco Pandolfi; Robin L. Modini; Fernando Velarde; Laura Renzi; Angela Marinoni; Jean‐Luc Jaffrezo; Isabel Moreno; Diego Aliaga
Abstract. Black carbon (BC) is a major component of submicron particulate matter (PM), with significant health and climate impacts. Many cities in emerging countries lack comprehensive knowledge about BC emissions and exposure levels. This study investigates BC concentration levels, identifies its emission sources, and characterizes the optical properties of BC at urban background sites of the two largest high-altitude Bolivian cities: La Paz (LP) (3600 m above sea level) and El Alto (EA) (4050 m a.s.l.), where atmospheric oxygen levels and intense radiation may affect BC production. The study relies on concurrent measurements of equivalent black carbon (eBC), elemental carbon (EC), and refractory black carbon (rBC) and their comparison with analogous data collected at the nearby Chacaltaya Global Atmosphere Watch Station (5240 m a.s.l). The performance of two independent source apportionment techniques was compared: a bilinear model and a least-squares multilinear regression (MLR). Maximum eBC concentrations were observed during the local dry season (LP: eBC = 1.5 ± 1.6 µg m−3; EA: 1.9±2.0 µg m−3). While eBC concentrations are lower at the mountain station, daily transport from urban areas is evident. Average mass absorption cross sections of 6.6–8.2 m2 g−1 were found in the urban area at 637 nm. Both source apportionment methods exhibited a reasonable level of agreement in the contribution of biomass burning (BB) to absorption. The MLR method allowed the estimation of the contribution and the source-specific optical properties for multiple sources, including open waste burning.
Atmospheric Concentrations of New Persistent Organic Pollutants and Emerging Chemicals of Concern in the Group of Latin America and Caribbean (GRULAC) Region
(American Chemical Society, 2018) Cassandra Rauert; Tom Harner; Jasmin K. Schuster; Anita Eng; Gilberto Fillmann; Luisa E. Castillo; Oscar Fentanes; Martı́n Villa Ibarra; Karina S.B. Miglioranza; Isabel Moreno
A special initiative was run by the Global Atmospheric Passive Sampling (GAPS) Network to provide atmospheric data on a range of emerging chemicals of concern and candidate and new persistent organic pollutants in the Group of Latin America and Caribbean (GRULAC) region. Regional-scale data for a range of flame retardants (FRs) including polybrominated diphenyl ethers (PBDEs), organophosphate esters (OPEs), and a range of alternative FRs (novel FRs) are reported over 2 years of sampling with low detection frequencies of the novel FRs. Atmospheric concentrations of the OPEs were an order of magnitude higher than all other FRs, with similar profiles at all sites. Regional-scale background concentrations of the poly- and perfluoroalkyl substances (PFAS), including the neutral PFAS (n-PFAS) and perfluoroalkyl acids (PFAAs), and the volatile methyl siloxanes (VMS) are also reported. Ethyl perfluorooctane sulfonamide (EtFOSA) was detected at highly elevated concentrations in Brazil and Colombia, in line with the use of the pesticide sulfluramid in this region. Similar concentrations of the perfluoroalkyl sulfonates (PFAS) were detected throughout the GRULAC region regardless of location type, and the VMS concentrations in air increased with the population density of sampling locations. This is the first report of atmospheric concentrations of the PFAAs and VMS from this region.
Biomass burning and urban emission impacts in the Andes Cordillera region based on in situ measurements from the Chacaltaya observatory, Bolivia (5240 m a.s.l.)
(Copernicus Publications, 2019) Aurélien Chauvigné; Diego Aliaga; Karine Sellegri; Nadège Montoux; Radovan Krejčí; Griša Močnik; Isabel Moreno; Thomas Müller; Marco Pandolfi; Fernando Velarde
Abstract. This study documents and analyses a 4-year continuous record of aerosol optical properties measured at the Global Atmosphere Watch (GAW) station of Chacaltaya (CHC; 5240 m a.s.l.), in Bolivia. Records of particle light scattering and particle light absorption coefficients are used to investigate how the high Andean Cordillera is affected by both long-range transport and by the fast-growing agglomeration of La Paz–El Alto, located approximately 20 km away and 1.5 km below the sampling site. The extended multi-year record allows us to study the properties of aerosol particles for different air mass types, during wet and dry seasons, also covering periods when the site was affected by biomass burning in the Bolivian lowlands and the Amazon Basin. The absorption, scattering, and extinction coefficients (median annual values of 0.74, 12.14, and 12.96 Mm−1 respectively) show a clear seasonal variation with low values during the wet season (0.57, 7.94, and 8.68 Mm−1 respectively) and higher values during the dry season (0.80, 11.23, and 14.51 Mm−1 respectively). The record is driven by variability at both seasonal and diurnal scales. At a diurnal scale, all records of intensive and extensive aerosol properties show a pronounced variation (daytime maximum, night-time minimum), as a result of the dynamic and convective effects. The particle light absorption, scattering, and extinction coefficients are on average 1.94, 1.49, and 1.55 times higher respectively in the turbulent thermally driven conditions than the more stable conditions, due to more efficient transport from the boundary layer. Retrieved intensive optical properties are significantly different from one season to the other, reflecting the changing aerosol emission sources of aerosol at a larger scale. Using the wavelength dependence of aerosol particle optical properties, we discriminated between contributions from natural (mainly mineral dust) and anthropogenic (mainly biomass burning and urban transport or industries) emissions according to seasons and local circulation. The main sources influencing measurements at CHC are from the urban area of La Paz–El Alto in the Altiplano and from regional biomass burning in the Amazon Basin. Results show a 28 % to 80 % increase in the extinction coefficients during the biomass burning season with respect to the dry season, which is observed in both tropospheric dynamic conditions. From this analysis, long-term observations at CHC provide the first direct evidence of the impact of biomass burning emissions of the Amazon Basin and urban emissions from the La Paz area on atmospheric optical properties at a remote site all the way to the free troposphere.
Biomass-burning and urban emission impacts in the Andes Cordillera region based on in-situ measurements from the Chacaltaya observatory, Bolivia (5240 m a.s.l.)
(2019) Chauvigné Aurélien; Diego Aliaga; Marcos Andrade; Patrick Ginot; Radovan Krejčí; Griša Močnik; Nadège Montoux; Isabel Moreno; Thomas Müller; Marco Pandolfi
Abstract. We present the variability of aerosol particle optical properties measured at the global Atmosphere Watch (GAW) station Chacaltaya (5240 m a.s.l.). The in-situ mountain site is ideally located to study regional impacts of the densely populated urban area of La Paz/El Alto, and the intensive activity in the Amazonian basin. Four year measurements allow to study aerosol particle properties for distinct atmospheric conditions as stable and turbulent layers, different airmass origins, as well as for wet and dry seasons, including biomass-burning influenced periods. The absorption, scattering and extinction coefficients (median annual values of 0.74, 12.14 and 12.96 Mm−1 respectively) show a clear seasonal variation with low values during the wet season (0.57, 7.94 and 8.68 Mm−1 respectively) and higher values during the dry season (0.80, 11.23 and 14.51 Mm−1 respectively). These parameters also show a pronounced diurnal variation (maximum during daytime, minimum during night-time, as a result of the dynamic and convective effects of leading to lower atmospheric layers reaching the site during daytime. Retrieved intensive optical properties are significantly different from one season to the other, showing the influence of different sources of aerosols according to the season. Both intensive and extensive optical properties of aerosols were found to be different among the different atmospheric layers. The particle light absorption, scattering and extinction coefficients are in average 1.94, 1.49 and 1.55 times higher, respectively, in the turbulent layer compared to the stable layer. We observe that the difference is highest during the wet season and lowest during the dry season. Using wavelength dependence of aerosol particle optical properties, we discriminated contributions from natural (mainly mineral dust) and anthropogenic (mainly biomass-burning and urban transport or industries) emissions according to seasons and tropospheric layers. The main sources influencing measurements at CHC are arising from the urban area of La Paz/El Alto, and regional biomass-burning from the Amazonian basin. Results show a 28 % to 80 % increase of the extinction coefficients during the biomass-burning season with respect to the dry season, which is observed in both tropospheric layers. From this analyse, long-term observations at CHC provides the first direct evidence of the impact of emissions in the Amazonian basin on atmospheric optical properties far away from their sources, all the way to the stable layer.
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.
CCN production by new particle formation in the free troposphere
(Copernicus Publications, 2017) Clémence Rose; Karine Sellegri; Isabel Moreno; Fernando Velarde; Michel Ramonet; Kay Weinhold; Radovan Krejčí; Marcos Andrade; Alfred Wiedensohler; Patrick Ginot
Abstract. Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on Chacaltaya (5240 m a.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ∼ 2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between 1 January and 31 December 2012, we found that 61 % of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, and 1481 cm−3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67 % against 53 % in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud-related radiative processes.
Comment on acp-2022-780
(2023) Valeria MardoÃ±ez; Marco Pandolfi; Lucille Joanna S. Borlaza; Jean‐Luc Jaffrezo; AndrÃ©s Alastuey; Jean‐Luc Besombes; Isabel Moreno; Noemí Pérez; GriÅ¡a MoÄ nik; Patrick Ginot
Abstract. La Paz and El Alto are two fast-growing high-altitude Bolivian cities forming the second largest metropolitan area in the country, located between 3200 and 4050 m a.s.l. Together they host a growing population of around 1.8 million people. The air quality in this conurbation is strongly influenced by urbanization. However, there are no comprehensive studies that have assessed the sources of air pollution and their impacts on health. Despite being neighboring cities, the drastic change in altitude and topography between La Paz and El Alto together with different socio-economic activities lead to different sources, dynamics and transport of particulate matter (PM). In this investigation, PM10 samples were collected at two urban background stations located in La Paz and El Alto between April 2016 and June 2017. The samples were later analyzed for a wide range of chemical species including numerous source tracers (OC, EC, water-soluble ions, sugar anhydrides, sugar alcohols, trace metals, and molecular organic species). The US-EPA Positive Matrix Factorization (PMF v.5.0) receptor model was then applied for source apportionment of PM10. This is the first source apportionment study in South America that incorporates a large set of organic markers (such as levoglucosan, polycyclic aromatic hydrocarbons – PAH, hopanes and alkanes) together with inorganic species. The multisite PMF resolved 11 main sources of PM. The largest annual contribution to PM10 came from two major sources: the ensemble of the four vehicular emissions sources (exhaust and non-exhaust), together responsible for 35 % and 25 % of the measured PM in La Paz and El Alto, respectively, and dust contributing 20 % and 32 % to the total. Secondary aerosols contributed 22 % (24 %) in La Paz (El Alto). Agriculture-related smoke from biomass burning originated in the Bolivian lowlands and neighboring countries contributed to 8 % (7 %) of the total PM10 mass annually. This contribution increased to 17 % (13 %) between August–October. Primary biogenic emissions were responsible for 13 % (7 %) of the measured PM10 mass. Finally, it was possible to identify a profile related to open waste burning occurring between the months of May and August. Despite the fact that this source contributed only to 2 % (5 %) of the total PM10 mass, it constitutes the second largest source of PAHs, compounds potentially hazardous to health. Our analysis resulted in the identification of two specific traffic-related sources. In addition, we also identified a lubricant source (not frequently identified) and a non-exhaust emissions source. This study shows that PM10 concentrations in La Paz and El Alto region are mostly impacted by a limited number of local sources. In conclusion, dust, traffic emissions, open waste burning and biomass burning are the main sources to target in order to improve air quality in both cities.
Comment on egusphere-2023-1298
(2023) Isabel Moreno; Radovan Krejčí; Jean‐Luc Jaffrezo; Gaëlle Uzu; Andrés Alástuey; Marcos Andrade; Valeria Mardóñez; Alkuin Maximilian Koenig; Diego Aliaga; Claudia Mohr
Abstract. The chemical composition of PM10 and PM2.5 was studied at the summit of Mt. Chacaltaya (5380 masl, lat.-16.346950º, lon. -68.128250º) providing a unique long-term record spanning from December 2011 to March 2020. The chemical composition of aerosol at the Chacaltaya GAW site is representative of the regional background, seasonally affected by biomass burning practices and by nearby anthropogenic emissions from the metropolitan area of La Paz – El Alto. Concentration levels are clearly influenced by seasons with minimum occurring during the wet season (December to March) and maxima occurring during the dry and transition seasons (April to November). Ions, total carbon (EC+OC) and saccharide concentrations range between 558–1785, 384–1120 and 4.3–25.5 ng m-3 for bulk PM10 and 917–2308, 519–1175 and 3.9–24.1 ng m-3 for PM2.5, respectively. Such concentrations are overall lower compared to other high-altitude stations around the globe, but higher than Amazonian remote sites (except for OC). For PM10, there is dominance of insoluble mineral matter (33–56 % of the mass), organic matter (7–34 %) and secondary inorganic aerosol (15–26 %). Chemical composition profiles were identified for different origins: EC, NO3-, NH4+, glucose, C2O4-2 for the nearby urban and rural areas; OC, EC, NO3-, K+, acetate, formiate, levoglucosan, some F- and Br- for biomass burning; MeSO3-, Na+, Mg2+, Br- for aged marine emissions from the Pacific Ocean; arabitol, mannitol, K+ for biogenic emissions; Na+, Ca2+, Mg2+ for soil dust, and SO42-, F-, and some Cl- for volcanism. Regional biomass-burning practices influence the soluble fraction of the aerosol particularly between July and September. The organic fraction is present all year round and has both anthropogenic (biomass burning and other combustion sources) and natural (primary and secondary biogenic emissions) origins, with the OC/EC mass ratio being practically constant all year round (10.5±38.9). Peruvian volcanism dominates the SO42- concentration since 2014, though it presents a strong temporal variability due to the intermittence of the sources and seasonal changes on the transport patterns. These measurements represent some of the first long-term observations of aerosol chemical composition at a continental high-altitude site in the tropical Southern hemisphere.
Comment on egusphere-2023-1298
(2023) Isabel Moreno; Radovan Krejčí; Jean‐Luc Jaffrezo; Gaëlle Uzu; Andrés Alástuey; Marcos Andrade; Valeria Mardóñez; Alkuin Maximilian Koenig; Diego Aliaga; Claudia Mohr
Abstract. The chemical composition of PM10 and PM2.5 was studied at the summit of Mt. Chacaltaya (5380 masl, lat.-16.346950º, lon. -68.128250º) providing a unique long-term record spanning from December 2011 to March 2020. The chemical composition of aerosol at the Chacaltaya GAW site is representative of the regional background, seasonally affected by biomass burning practices and by nearby anthropogenic emissions from the metropolitan area of La Paz – El Alto. Concentration levels are clearly influenced by seasons with minimum occurring during the wet season (December to March) and maxima occurring during the dry and transition seasons (April to November). Ions, total carbon (EC+OC) and saccharide concentrations range between 558–1785, 384–1120 and 4.3–25.5 ng m-3 for bulk PM10 and 917–2308, 519–1175 and 3.9–24.1 ng m-3 for PM2.5, respectively. Such concentrations are overall lower compared to other high-altitude stations around the globe, but higher than Amazonian remote sites (except for OC). For PM10, there is dominance of insoluble mineral matter (33–56 % of the mass), organic matter (7–34 %) and secondary inorganic aerosol (15–26 %). Chemical composition profiles were identified for different origins: EC, NO3-, NH4+, glucose, C2O4-2 for the nearby urban and rural areas; OC, EC, NO3-, K+, acetate, formiate, levoglucosan, some F- and Br- for biomass burning; MeSO3-, Na+, Mg2+, Br- for aged marine emissions from the Pacific Ocean; arabitol, mannitol, K+ for biogenic emissions; Na+, Ca2+, Mg2+ for soil dust, and SO42-, F-, and some Cl- for volcanism. Regional biomass-burning practices influence the soluble fraction of the aerosol particularly between July and September. The organic fraction is present all year round and has both anthropogenic (biomass burning and other combustion sources) and natural (primary and secondary biogenic emissions) origins, with the OC/EC mass ratio being practically constant all year round (10.5±38.9). Peruvian volcanism dominates the SO42- concentration since 2014, though it presents a strong temporal variability due to the intermittence of the sources and seasonal changes on the transport patterns. These measurements represent some of the first long-term observations of aerosol chemical composition at a continental high-altitude site in the tropical Southern hemisphere.
Comment on egusphere-2024-770
(2024) Valeria Mardoñez-Balderrama; Griša Močnik; Marco Pandolfi; Robin L. Modini; Fernando Velarde; Laura Renzi; Angela Marinoni; Jean‐Luc Jaffrezo; Isabel Moreno; Diego Aliaga
Abstract. Black carbon (BC) is a major component of sub-micron particulate matter (PM) with significant health and climate impacts. Many cities in emerging countries lack comprehensive knowledge about BC emissions and exposure levels. This study investigates BC concentration levels, identify its emission sources, and characterize the optical properties of BC at urban background sites of the two largest high-altitude Bolivian cities: La Paz (LP) (3600 m above sea level) and El Alto (EA) (4050 m a.s.l.) where atmospheric oxygen levels and intense radiation may affect BC production. The study relies on concurrent measurements of equivalent black carbon (eBC), elemental carbon (EC), and refractory black carbon (rBC), and their comparison with analogous data collected at the nearby Global Atmosphere Watch-Chacaltaya station (5240 m a.s.l). The performance of two independent source-apportionment techniques was compared: a bilinear model and a least squares multilinear regression (MLR). Maximum eBC concentrations were observed during the local dry season (LP: eBC=1.5±1.6 μg m-3; EA: 1.9±2.0 μg m-3). While eBC concentrations are lower at the mountain station, daily transport from urban areas is evident. Average mass absorption cross sections of 6.6-8.2 m2 g-1 were found in the urban area at 637 nm. Both source apportionment methods exhibited a reasonable level of agreement in the contribution of biomass burning (BB) to absorption. The MLR method allowed the estimation of the contribution and the source-specific optical properties for multiple sources including open waste burning.
Data and Code for figures of "Long-range transport and fate of DMS-oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes"
(European Organization for Nuclear Research, 2022) Wiebke Scholz; Jiali Shen; Diego Aliaga; Cheng Wu; Samara Carbone; Isabel Moreno; Qiaozhi Zha; Wei Huang; Liine Heikkinen; Jean‐Luc Jaffrezo
This database includes the material to create the figures in "Measurement Report: Long-range transport and fate of DMS-oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes" and the analyzed time series of all atmospheric variables presented.
Data and Code for figures of "Long-range transport and fate of DMS-oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes"
(2022) Wiebke Scholz; Jiali Shen; Diego Aliaga; Cheng Wu; Samara Carbone; Isabel Moreno; Qiaozhi Zha; Wei Huang; Liine Heikkinen; Jean‐Luc Jaffrezo
This database includes the material to create the figures in "Measurement Report: Long-range transport and fate of DMS-oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes" and the analyzed time series of all atmospheric variables presented.
Data and Code for figures of "Long-range transport and fate of DMS-oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes"
(European Organization for Nuclear Research, 2022) Wiebke Scholz; Jiali Shen; Diego Aliaga; Cheng Wu; Samara Carbone; Isabel Moreno; Qiaozhi Zha; Wei Huang; Liine Heikkinen; Jean‐Luc Jaffrezo
This database includes the material to create the figures in "Measurement Report: Long-range transport and fate of DMS-oxidation products in the free troposphere derived from observations at the high-altitude research station Chacaltaya (5240 m a.s.l.) in the Bolivian Andes" and the analyzed time series of all atmospheric variables presented.
Effects of undetected data quality issues on climatological analyses
(2017) Stefan Hunziker; Stefan Brönnimann; Juan Marcos Calle; Isabel Moreno; Marcos Andrade; Laura Ticona; Adrian Huerta; Waldo Lavado‐Casimiro
Abstract. Systematic data quality issues may occur at various stages of the data generation process. They may affect large fractions of observational datasets and remain largely undetected with standard data quality control. This study investigates the effects of such undetected data quality issues on the results of climatological analyses. For this purpose, we quality controlled daily observations of manned weather stations from the Central Andean area with a standard and an enhanced approach. The climate variables analysed are minimum and maximum temperature, and precipitation. About 40 % of the observations are inappropriate for the calculation of monthly temperature means and precipitation sums due to data quality issues. These quality problems undetected with the standard quality control method strongly affect climatological analyses, since they reduce the correlation coefficients of station pairs, deteriorate the performance of data homogenization methods, increase the spread of individual station trends, and significantly bias regional temperature trends. Our findings indicate that undetected data quality issues are included in important and frequently used observational datasets, and hence may affect a high number of climatological studies. It is of utmost importance to apply comprehensive and adequate data quality control approaches on manned weather station records in order to avoid biased results and large uncertainties.
Effects of undetected data quality issues on climatological analyses
(Copernicus Publications, 2018) Stefan Hunziker; Stefan Brönnimann; Juan Marcos Calle; Isabel Moreno; Marcos Andrade; Laura Ticona; Adrian Huerta; Waldo Lavado‐Casimiro
Abstract. Systematic data quality issues may occur at various stages of the data generation process. They may affect large fractions of observational datasets and remain largely undetected with standard data quality control. This study investigates the effects of such undetected data quality issues on the results of climatological analyses. For this purpose, we quality controlled daily observations of manned weather stations from the Central Andean area with a standard and an enhanced approach. The climate variables analysed are minimum and maximum temperature and precipitation. About 40 % of the observations are inappropriate for the calculation of monthly temperature means and precipitation sums due to data quality issues. These quality problems undetected with the standard quality control approach strongly affect climatological analyses, since they reduce the correlation coefficients of station pairs, deteriorate the performance of data homogenization methods, increase the spread of individual station trends, and significantly bias regional temperature trends. Our findings indicate that undetected data quality issues are included in important and frequently used observational datasets and hence may affect a high number of climatological studies. It is of utmost importance to apply comprehensive and adequate data quality control approaches on manned weather station records in order to avoid biased results and large uncertainties.
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;