scholarly journals Significant seasonal changes in optical properties of brown carbon in the midlatitude atmosphere

2020 ◽  
Vol 20 (5) ◽  
pp. 2709-2718 ◽  
Author(s):  
Heejun Han ◽  
Guebuem Kim ◽  
Hojong Seo ◽  
Kyung-Hoon Shin ◽  
Dong-Hun Lee
Keyword(s):  
Seasonal Changes ◽  
Organic Aerosols ◽  
Warm Season ◽  
Cold Season ◽  
Water Soluble ◽  
Significant Shift ◽  
Brown Carbon ◽  
Back Trajectories ◽  
Different Seasons ◽  
Property Changes

Abstract. Atmospheric brown carbon (BrC) plays significant roles in the light absorption and photochemistry of the atmosphere. Although the sources and occurrences of BrC have been studied extensively, its removal processes and optical characteristics in the atmosphere have been poorly understood. In this study, we examined the seasonal changes in sources and sinks of BrC and water-soluble organic carbon (WSOC) in the atmosphere of Seoul, South Korea. Our results showed that the concentrations of BrC and WSOC decreased by approximately 80 % and 30 %, respectively, from the cold season (October–January) to the warm season (June–September). Excitation–emission matrix (EEM) spectra showed that the humic-like substance (HULIS) was the dominant fraction of BrC as the other components were not measurable. The air mass back trajectories of fire burning practices and the variations in non-crustal potassium (K) and vanadium (V) contents in the water-soluble aerosols during all seasons showed no measurable decrease in input of biomass-burning sources in summer. However, there was a significant shift in photo-resistivity of light-absorbing organic aerosols in the summer, indicating larger removals of ultraviolet (UV) degradable BrC. This trend is supported by laboratory UV radiation experiments on the optical property changes of BrC and WSOC in aerosol samples. Thus, our results suggest that the photodegradation has dominant roles in controlling the quantity and quality of light-absorbing organic aerosols in the different seasons in the midlatitude atmosphere.

scholarly journals Significant seasonal changes in optical properties of brown carbon in the mid-latitude atmosphere

2019 ◽  
Author(s):  
Heejun Han ◽  
Guebuem Kim ◽  
Kyung-Hoon Shin ◽  
Dong-Hun Lee
Keyword(s):  
Seasonal Changes ◽  
Organic Aerosols ◽  
Warm Season ◽  
Cold Season ◽  
Water Soluble ◽  
Significant Shift ◽  
Brown Carbon ◽  
Back Trajectories ◽  
Different Seasons ◽  
Property Changes

Abstract. Atmospheric brown carbon (BrC) plays significant roles in the light absorption and photochemistry of the atmosphere. Although the occurrence and sources of BrC have been studied extensively, its removal processes and optical characteristics in the atmosphere have been poorly understood. In this study, we examined the seasonal changes in sources and sinks of BrC and water-soluble organic carbon (WSOC) in the atmosphere of Seoul, Korea. Our results showed that the concentrations of BrC and WSOC decreased by approximately 80 % and 30 %, respectively, from the cold season (Oct–Jan) to the warm season (Jun–Sep). Excitation–emission matrix (EEM) spectra showed that the humic-like substance (HULIS) was the dominant fraction of BrC as the other components were not measurable. The air mass back trajectories of fire burning practices and the variations in K and V contents in the water-soluble aerosols during all seasons showed no measureable decrease in input of biomass-burning sources in summer. However, there was a significant shift in photo-resistivity of light-absorbing organic aerosols in the summer, indicating significantly larger removals of ultraviolet (UV) degradable BrC. This was confirmed by laboratory UV radiation experiments on the optical property changes of BrC and WSOC in aerosol samples. Thus, our results suggest that the photo-degradation has dominant roles in controlling the quantity and quality of light-absorbing organic aerosols in the different seasons in the mid-latitude atmosphere.

scholarly journals The role of phytophysiognomies and seasonality on the structure of ground-dwelling anuran (Amphibia) in the Pampa biome, southern Brazil

2013 ◽  
Vol 85 (3) ◽  
pp. 1105-1116 ◽  
Author(s):  
FRANCIELE P. MARAGNO ◽  
TIAGO G. SANTOS ◽  
SONIA Z. CECHIN
Keyword(s):  
Paired Comparison ◽  
Warm Season ◽  
Cold Season ◽  
Pitfall Traps ◽  
Southern Brazil ◽  
Environmental Features ◽  
Pampa Biome ◽  
Different Seasons ◽  
Pseudis Minuta

ABSTRACT Considering that habitat use by amphibians is related both with climate and environmental features, we tested the hypothesis that anuran assemblages found in different phytophysiognomies and in different seasons vary in structure. Additionally, we searched for species which can be indicators of habitat and seasons. The study was conducted in the Pampa biome, southern Brazil. Sampling was done through pitfall traps placed in three phytophysiognomies: grassland, ecotone grassland/forest; and forest. The seasonality factor was created by grouping months in warn and cold seasons. Sixteen species were found and the assemblages were influenced both by phytophysiognomies and climatic seasonality. In a paired comparison, the three phytophysiognomies differed in structure of assemblage from each other. Physalaemus henselii, P. riograndensis, Pseudopaludicola falcipes and Pseudis minuta were indicators of ecotone. Leptodactylus gracilis and Physalaemus biligonigerus were indicators of grassland. None species was indicator of forest. Most of the species were indicators of warm season: Elachistocleis bicolor, Leptodactylus fuscus, L. gracilis, L. latinasus, L. latrans, L. mystacinus, Physalaemus biligonigerus, P. cuvieri and Pseudis minuta. None species was indicator of cold season. We found that even for species of open areas, as Pampa, heterogeneous phytophysiognomies are important for maintaining abundance and constancy of populations of anuran.

scholarly journals An Objectively Determined Blocking Index and its Northern Hemisphere Climatology

2013 ◽  
Vol 27 (8) ◽  
pp. 2948-2970 ◽  
Author(s):  
David Small ◽  
Eyad Atallah ◽  
John R. Gyakum
Keyword(s):  
Northern Hemisphere ◽  
Systematic Approach ◽  
Intraseasonal Variability ◽  
Warm Season ◽  
Cold Season ◽  
Central Pacific ◽  
Anticyclonic Circulation ◽  
Blocking Activity ◽  
Different Seasons ◽  
Blocking Index

Abstract A modified blocking index is defined based on vertically integrated potential vorticity. The application of this index identifies blocking activity over the Northern Hemisphere during all seasons. The index is developed by systematically identifying the magnitude and spatial scale that best characterizes persistent anticyclonic circulation anomalies in different seasons. By applying a systematic approach to the detection of blocking, the interannual, seasonal, and intraseasonal patterns of blocking frequency across the Northern Hemisphere are able to be characterized. The results are consistent with previous studies in finding that blocking is more frequent in the cold season months than in the warm season, although the results suggest that blocking occurs much more frequently in the summer and fall than many studies have previously reported. By examining blocking frequency monthly, interesting patterns of intraseasonal variability are found, especially over the central Pacific in August and the eastern Pacific in September and October, where blocking is nearly as frequent as in the winter. Possible explanations for this intraseasonal variability are discussed.

scholarly journals Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry

2012 ◽  
Vol 12 (7) ◽  
pp. 3557-3571 ◽  
Author(s):  
K. E. Altieri ◽  
M. G. Hastings ◽  
A. J. Peters ◽  
D. M. Sigman
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
High Resolution ◽  
Electrospray Ionization ◽  
Organic Nitrogen ◽  
Warm Season ◽  
Cold Season ◽  
Water Soluble ◽  
Air Mass ◽  
Soluble Organic Nitrogen

Abstract. Atmospheric water soluble organic nitrogen (WSON) is a subset of the complex organic matter in aerosols and rainwater, which impacts cloud condensation processes and aerosol chemical and optical properties and may play a significant role in the biogeochemical cycle of N. However, its sources, composition, connections to inorganic N, and variability are largely unknown. Rainwater samples were collected on the island of Bermuda (32.27° N, 64.87° W), which experiences both anthropogenic and marine influenced air masses. Samples were analyzed by ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to chemically characterize the WSON. Elemental compositions of 2281 N containing compounds were determined over the mass range m/z+ 50 to 500. The five compound classes with the largest number of elemental formulas identified, in order from the highest number of formulas to the lowest, contained carbon, hydrogen, oxygen, and nitrogen (CHON+), CHON compounds that contained sulfur (CHONS+), CHON compounds that contained phosphorus (CHONP+), CHON compounds that contained both sulfur and phosphorus (CHONSP+), and compounds that contained only carbon, hydrogen, and nitrogen (CHN+). Compared to rainwater collected in the continental USA, average O:C ratios of all N containing compound classes were lower in the marine samples whereas double bond equivalent values were higher, suggesting a reduced role of secondary formation mechanisms. Despite their prevalence in continental rainwater, no organonitrates or nitrooxy-organosulfates were detected, but there was an increased presence of organic S and organic P containing compounds in the marine rainwater. Cluster analysis showed a clear chemical distinction between samples collected during the cold season (October to March) which have anthropogenic air mass origins and samples collected during the warm season (April to September) with remote marine air mass origins. This, in conjunction with patterns identified in van Krevelen diagrams, suggests that the cold season WSON is a mixture of organic matter with both marine and anthropogenic sources while in the warm season the WSON appears to be dominated by marine sources. These findings indicate that, although the concentrations and percent contribution of WSON to total N is fairly consistent across diverse geographic regions, the chemical composition of WSON varies strongly as a function of source region and atmospheric environment.

scholarly journals Molecular characterization of water soluble organic nitrogen in marine rainwater by ultra-high resolution electrospray ionization mass spectrometry

2011 ◽  
Vol 11 (11) ◽  
pp. 31283-31321
Author(s):  
K. E. Altieri ◽  
M. G. Hastings ◽  
A. J. Peters ◽  
D. M. Sigman
Keyword(s):  
Mass Spectrometry ◽  
Organic Matter ◽  
High Resolution ◽  
Electrospray Ionization ◽  
Organic Nitrogen ◽  
Warm Season ◽  
Cold Season ◽  
Water Soluble ◽  
Air Mass ◽  
Soluble Organic Nitrogen

Abstract. Atmospheric water soluble organic nitrogen (WSON) is a subset of the complex organic matter in aerosols and rainwater, which impacts cloud condensation processes and aerosol chemical and optical properties, and may play a significant role in the biogeochemical cycle of N. However, its sources, composition, connections to inorganic N, and variability are largely unknown. Rainwater samples were collected on the island of Bermuda (32.27° N, 64.87° W), which experiences both anthropogenic and marine influenced air masses. Samples were analyzed by ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry to chemically characterize the WSON. Elemental compositions of 2455 N containing compounds were determined over the mass range m/z+ 50 to 500. The five compound classes with the largest number of elemental formulas identified, in order from the highest number of formulas to the lowest, contained carbon, hydrogen, oxygen, and nitrogen (CHON+), CHON compounds that contained sulfur (CHONS+), CHON compounds that contained phosphorous (CHONP+), CHON compounds that contained both sulfur and phosphorous (CHONSP+), and compounds that contained only carbon, hydrogen, and nitrogen (CHN+). No organonitrates or nitrooxy-organosulfates were detected, but there was an increased presence of organic S and organic P containing compounds in the marine rainwater. Compared to rainwater collected in the continental USA, average O:C ratios of all N containing compound classes were lower in the marine samples whereas double bond equivalent values were higher, suggesting a reduced role of secondary formation mechanisms. Cluster analysis showed a clear chemical distinction between samples collected during the cold season (October to March) which have anthropogenic air mass origins and samples collected during the warm season (April to September) with remote marine air mass origins. This, in conjunction with patterns identified in van Krevelen diagrams, suggests that the cold season WSON is a mixture of organic matter with both marine and anthropogenic sources while in the warm season the WSON appears to be dominated by marine sources. These findings indicate that, although the concentrations and percent contribution of WSON to total N is fairly consistent across diverse geographic regions, the chemical composition of WSON varies strongly as a function of source region and atmospheric environment.

scholarly journals An Object-based Climatology of Precipitation Systems in Sydney, Australia

2021 ◽  
Author(s):  
Hooman Ayat ◽  
Jason P. Evans ◽  
Steven C. Sherwood ◽  
Joshua Soderholm
Keyword(s):  
Cell Tracking ◽  
Clustering Algorithms ◽  
Warm Season ◽  
Radar Data ◽  
Cold Season ◽  
Translation Speed ◽  
Precipitation System ◽  
Different Seasons ◽  
Storm Characteristics ◽  
Sydney Australia

Abstract The climate is warming and this is changing some aspects of storms, but we have relatively little knowledge of storm characteristics beyond intensity, which limits our understanding of storms overall. In this study, we apply a cell-tracking algorithm to 20 years of radar data at a mid-latitude coastal-site (Sydney, Australia), to establish a regional precipitation system climatology. The results show that extreme storms in terms of translation-speed, size and rainfall intensity usually occur in the warm season, and are slower and more intense over land between ~10am and ~8pm (AEST), peaking in the afternoon. Precipitation systems are more frequent in the cold season and often initiate over the ocean and move northward, leading to precipitation mostly over the ocean. Using clustering algorithms, we have found five precipitation system types with distinct properties, occurring throughout the year but peaking in different seasons. While overall rainfall statistics don't show any link to climate modes, links do appear for some system types using a multivariate approach. This climatology for a variety of precipitation system characteristics will allow future study of any changes in these characteristics due to climate change.

scholarly journals Assessment of the Spatial and Seasonal Variation of the Error–Intensity Relationship in Satellite-Based Precipitation Measurements Using an Adaptive Parametric Model

2015 ◽  
Vol 16 (4) ◽  
pp. 1700-1716 ◽  
Author(s):  
Hao Liu ◽  
Soroosh Sorooshian ◽  
Xiaogang Gao
Keyword(s):  
Warm Season ◽  
Stage Iv ◽  
Cold Season ◽  
Parametric Model ◽  
Spatial And Seasonal Variation ◽  
Number Of Factors ◽  
Proposed Model ◽  
Different Seasons ◽  
Pdf Model ◽  
The Relationship

Abstract Studies have been reported about the efficacy of satellites for measuring precipitation and about quantifying their errors. Based on these studies, the errors are associated with a number of factors, among them, intensity, location, climate, and season of the year. Several error models have been proposed to assess the relationship between the error and the rainfall intensity. However, it is unknown whether these models are adaptive to different seasons, different regions, or different types of satellite-based estimates. Therefore, how the error–intensity relationship varies with the season or region is unclear. To investigate these issues, a parametric joint pdf model is proposed to analyze and study the 9-yr satellite-derived precipitation datasets of Climate Prediction Center (CPC) morphing technique (CMORPH); PERSIANN; and the real-time TRMM product 3B42, version 7 (TRMM-3B42-RTV7). The NEXRAD Stage IV product is the ground reference. The adaptability of the proposed model is verified by applying it to three locations (Oklahoma, Montana, and Florida) and by applying it to cold season, warm season, and the entire year. Then, the heteroscedasticities in the errors of satellite-based precipitation measurements are investigated using the proposed model under those scenarios. The results show that the joint pdfs have the same formulation under these scenarios, whereas their parameter sets were adaptively adjusted. This parametric model reveals detailed information about the spatial and seasonal variations of the satellite-based precipitation measurements. It is found that the shape of the conditional pdf shifts across the intensity ranges. At the ~10–20 mm day−1 range, the conditional pdf is L shaped, while at the ~40–60 mm day−1 range, it becomes more bell shaped. It is also concluded that no single satellite-based precipitation product outperforms others with respect to the different scenarios (i.e., seasons, regions, and climates).

scholarly journals A Radar Object-Based Examination of Rain System Climatology and Including Climate Variability

2021 ◽  
Author(s):  
Hooman Ayat ◽  
Jason P. Evans ◽  
Steven C. Sherwood ◽  
Joshua Soderholm
Keyword(s):  
Cell Tracking ◽  
Clustering Algorithms ◽  
Warm Season ◽  
Radar Data ◽  
Cold Season ◽  
Translation Speed ◽  
Different Seasons ◽  
A Cell ◽  
Storm Characteristics ◽  
Rainfall Statistics

Abstract We know the climate is warming and this is changing some aspects of storms, but we have little knowledge of storm characteristics beyond intensity, which limits our understanding of storms overall. In this study, we apply a cell-tracking algorithm to 20 years of radar data at a mid-latitude coastal-site (Sydney, Australia), to establish a regional storm climatology. The results show that extreme storms in terms of translation-speed, size and rainfall intensity usually occur in the warm season, and are slower and more intense over land between ~10am and ~8pm (AEST), peaking in the afternoon. Storms are more frequent in the cold season and often initiate over the ocean and move northward, leading to precipitation mostly over the ocean. Using clustering algorithms, we have found five storm types with distinct properties, occurring throughout the year but peaking in different seasons. While overall rainfall statistics don't show any link to climate modes, links do appear for some storm types using a multivariate approach. This climatology for a variety of storm characteristics will allow future study of any changes in these characteristics due to climate change.

scholarly journals Long-term brown carbon and smoke tracer observations in Bogotá, Colombia: association with medium-range transport of biomass burning plumes

2020 ◽  
Vol 20 (12) ◽  
pp. 7459-7472 ◽  
Author(s):  
Juan Manuel Rincón-Riveros ◽  
Maria Alejandra Rincón-Caro ◽  
Amy P. Sullivan ◽  
Juan Felipe Mendez-Espinosa ◽  
Luis Carlos Belalcazar ◽  
...  
Keyword(s):  
Air Quality ◽  
South America ◽  
Biomass Burning ◽  
Water Soluble ◽  
Radiation Budget ◽  
Strong Impact ◽  
Brown Carbon ◽  
Back Trajectories ◽  
Northern South America ◽  
The City

Abstract. Light-absorbing aerosols emitted during open biomass burning (BB) events such as wildfires and agricultural burns have a strong impact on the Earth's radiation budget through both direct and indirect effects. Additionally, BB aerosols and gas-phase emissions can substantially reduce air quality at local, regional, and global scales, negatively affecting human health. South America is one of largest contributors to BB emissions globally. After Amazonia, the BB emissions from wildfires and agricultural burns in the grassland plains of northern South America (NSA) are the most significant in the region. However, few studies have analyzed the potential impact of NSA BB emissions on regional air quality. Recent evidence suggests that seasonal variations in air quality in several major cities in NSA could be associated with open biomass burning emissions, but it is still uncertain to what extent those sources impact air quality in the region. In this work, we report on 3 years of continuous equivalent black carbon (eBC) and brown carbon (BrC) observations at a hilltop site located upwind of the city of Bogotá, and we demonstrate its association with fires detected by the MODerate-resolution Imaging Spectroradiometer (MODIS) in a 3000 km × 2000 km domain. Offline PM2.5 filter samples collected during three field campaigns were analyzed to quantify water-soluble organic carbon (WSOC), organic and elemental carbon (OC∕EC), and biomass burning tracers such as levoglucosan, galactosan, and potassium. MODIS active fire data and HYSPLIT back trajectories were used to identify potential biomass burning plumes transported to the city. We analyzed the relationship between BrC, WSOC, water-soluble potassium, and levoglucosan to identify signals of the regional transport of BB aerosols. Our results confirm that regional biomass burning transport from wildfires occurs annually during the months of January and April. The seasonality of eBC closely followed that of PM2.5 at the city air quality stations; however, the observed seasonality of BrC is distinctly different to that of eBC and strongly associated with regional fire counts. The strong correlation between BrC and regional fire counts was observed at daily, weekly, and monthly timescales. WSOC at the measurement site was observed to increase linearly with levoglucosan during high BB periods and to remain constant at ∼2.5 µgC m−3 during the low BB seasons. Our findings show, for the first time in this region, that aged BB plumes can regularly reach densely populated areas in the Central Andes of northern South America. A source footprint analysis involving BrC observations, back trajectories, and remotely sensed fire activity shows that the eastern savannas in NSA are the main BB source region for the domain analyzed.

scholarly journals Long-term Brown Carbon and Smoke Tracer Observations in Bogotá, Colombia: Association to Medium-Range Transport of Biomass Burning Plumes

2020 ◽  
Author(s):  
Juan Manuel Rincón-Riveros ◽  
Maria Alejandra Rincón-Caro ◽  
Amy P. Sullivan ◽  
Juan Felipe Mendez-Espinosa ◽  
Luis Carlos Belalcazar ◽  
...  
Keyword(s):  
Air Quality ◽  
South America ◽  
Biomass Burning ◽  
Water Soluble ◽  
Radiation Budget ◽  
Strong Impact ◽  
Brown Carbon ◽  
Back Trajectories ◽  
Northern South America ◽  
The City

Abstract. Light-absorbing aerosols emitted during open biomass burning (BB) events such as wildfires and agricultural burns have a strong impact on the Earth’s radiation budget through both direct and indirect effects. Additionally, BB aerosols and gas-phase emissions can substantially reduce air quality at local, regional, and global scales, negatively affecting human health. South America is one of largest contributors to BB emissions globally. After Amazonia, the BB emissions from the wildfires and agricultural burns in the grassland plains of Northern South America (NSA) are the most significant in the region. However, few studies have analyzed the potential impact of NSA BB emissions on regional air quality. Recent evidence suggests that seasonal variations in air quality in several major cities in NSA could be associated with open biomass burning emissions, but it is still uncertain to what those sources impact air quality in the region. In this work, we report on 3 years of continuous equivalent Black Carbon (eBC) and Brown Carbon (BrC) observations at a hill-top site located upwind of the city of Bogotá and we demonstrate its association with MODIS detected fires in a 3000 km × 2000 km domain. Off-line PM2.5 filter samples collected during three field campaigns were analyzed to quantify water-soluble organic carbon (WSOC), organic and elemental carbon (OC/EC), and biomass burning tracers such as levoglucosan, galactosan, and potassium. MODIS Active Fire Data and HYSPLIT back-trajectories were used to identify potential biomass burning plumes transported to the city. We analyzed the relationship between BrC, WSOC, water-soluble potassium, and levoglucosan to identify signals of regional transport of BB aerosols. Our results confirm that regional biomass burning transport from wildfires occurs annually during the months of January and April. The seasonality of eBC followed closely that of PM2.5 at the city air quality stations, however, the observed seasonality of BrC is distinctly different to that of eBC and strongly associated to regional fire counts. The strong correlation between BrC and regional fire counts was observed both at daily, weekly, and monthly time-scales. WSOC at the measurement site was observed to increase linearly with levoglucosan during high BB periods, and to remain constant at ∼ 2.5 µgC m−3 during the low BB activity seasons. Our findings show, for the first time in this region, that aged BB plumes can regularly reach densely populated areas in the Central Andes of Northern South America. A source footprint analysis involving BrC observations, back-trajectories, and remotely sensed fire activity shows that the eastern savannas in NSA are the main BB source region for the domain analyzed.

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