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  1. Book ; Online: Assessing potential indicators of aerosol wet scavenging during long-range transport

    Hilario, Miguel Ricardo A. / Arellano, Avelino F. / Behrangi, Ali / Crosbie, Ewan C. / DiGangi, Joshua P. / Diskin, Glenn S. / Shook, Michael A. / Ziemba, Luke D. / Sorooshian, Armin

    eISSN: 1867-8548

    2024  

    Abstract: As one of the dominant sinks of aerosol particles, wet scavenging greatly influences aerosol lifetime and interactions with clouds, precipitation, and radiation. However, wet scavenging remains highly uncertain in models, hindering accurate predictions ... ...

    Abstract As one of the dominant sinks of aerosol particles, wet scavenging greatly influences aerosol lifetime and interactions with clouds, precipitation, and radiation. However, wet scavenging remains highly uncertain in models, hindering accurate predictions of aerosol spatiotemporal distributions and downstream interactions. In this study, we present a flexible, computationally inexpensive method to identify meteorological variables relevant for estimating wet scavenging using a combination of aircraft, satellite, and reanalysis data augmented by trajectory modeling to account for air mass history. We assess the capabilities of an array of meteorological variables to predict the transport efficiency of black carbon (TE BC ) using a combination of nonlinear regression, curve fitting, and k -fold cross-validation. We find that accumulated precipitation along trajectories (APT) – treated as a wet scavenging indicator across multiple studies – does poorly when predicting TE BC . Among different precipitation characteristics (amount, frequency, intensity), precipitation intensity was the most effective at estimating TE BC but required longer trajectories ( >48 h) and including only intensely precipitating grid cells. This points to the contribution of intense precipitation to aerosol scavenging and the importance of accounting for air mass history. Predictors that were most able to predict TE BC were related to the distribution of relative humidity (RH) or the frequency of humid conditions along trajectories, suggesting that RH is a more robust way to estimate TE BC than APT. We recommend the following alternatives to APT when estimating aerosol scavenging: (1) the 90th percentile of RH along trajectories, (2) the fraction of hours along trajectories with either water vapor mixing ratios >15 g kg −1 or RH >95 %, and (3) precipitation intensity along trajectories at least 48 h along and filtered for grid cells with precipitation >0.2 mm h −1 . Future scavenging parameterizations should consider these ...
    Subject code 333
    Language English
    Publishing date 2024-01-05
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Book ; Online: Identifying Better Indicators of Aerosol Wet Scavenging During Long-Range Transport

    Hilario, Miguel Ricardo A. / Arellano, Avelino F. / Behrangi, Ali / Crosbie, Ewan C. / DiGangi, Joshua P. / Diskin, Glenn S. / Shook, Michael A. / Ziemba, Luke D. / Sorooshian, Armin

    eISSN:

    2024  

    Abstract: As one of the dominant sinks of aerosol particles, wet scavenging greatly influences aerosol lifetime and interactions with clouds, precipitation, and radiation. However, wet scavenging remains highly uncertain in models, hindering accurate predictions ... ...

    Abstract As one of the dominant sinks of aerosol particles, wet scavenging greatly influences aerosol lifetime and interactions with clouds, precipitation, and radiation. However, wet scavenging remains highly uncertain in models, hindering accurate predictions of aerosol spatiotemporal distributions and downstream interactions. In this study, we present a flexible, computationally inexpensive method to identify meteorological variables relevant for estimating wet scavenging using a combination of aircraft, satellite, and reanalysis data augmented by trajectory modeling to account for air mass history. We assess the capabilities of an array of meteorological variables to predict the transport efficiency of black carbon (TE BC ) using a combination of nonlinear regression, curve fitting, and k -fold cross-validation. We find that accumulated precipitation along trajectories (APT) – treated as a wet scavenging indicator across multiple studies – does poorly when predicting TE BC . Among different precipitation characteristics (amount, frequency, intensity), precipitation intensity was the most effective at estimating TE BC but required longer trajectories ( >48 h) and including only intensely precipitating grid cells. This points to the contribution of intense precipitation to aerosol scavenging and the importance of accounting for air mass history. Predictors that were most able to predict TE BC were related to the distribution of relative humidity (RH) or the frequency of humid conditions along trajectories, suggesting that RH is a more robust way to estimate TE BC than APT. We recommend the following alternatives to APT when estimating aerosol scavenging: (1) the 90th percentile of RH along trajectories, (2) the fraction of hours along trajectories with either water vapor mixing ratios >15 g kg −1 or RH >95 %, and (3) precipitation intensity along trajectories at least 48 h along and filtered for grid cells with precipitation >0.2 mm h −1 . Future scavenging parameterizations should consider these ...
    Subject code 333
    Language English
    Publishing date 2024-01-05
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article: Contrasting wet deposition composition between three diverse islands and coastal North American sites.

    Ma, Lin / Dadashazar, Hossein / Hilario, Miguel Ricardo A / Cambaliza, Maria Obiminda / Lorenzo, Genevieve Rose / Simpas, James Bernard / Nguyen, Phu / Sorooshian, Armin

    Atmospheric environment (Oxford, England : 1994)

    2020  Volume 244

    Abstract: This study examined spatial variations of precipitation accumulation and chemistry for six sites located on the West and East Coasts of the U.S., and one site each on the islands of Hawaii, Bermuda, and Luzon of the Philippines (specifically Manila). The ...

    Abstract This study examined spatial variations of precipitation accumulation and chemistry for six sites located on the West and East Coasts of the U.S., and one site each on the islands of Hawaii, Bermuda, and Luzon of the Philippines (specifically Manila). The nine coastal sites ranged widely in both mean annual precipitation accumulation, ranging from 40 cm (Mauna Loa, Hawaii) to 275 cm (Washington), and in terms of monthly profiles. The three island sites represented the extremes of differences in terms of chemical profiles, with Bermuda having the highest overall ion concentrations driven mainly by sea salt, Hawaii having the highest
    Language English
    Publishing date 2020-09-28
    Publishing country England
    Document type Journal Article
    ZDB-ID 216368-8
    ISSN 1352-2310 ; 0004-6981
    ISSN 1352-2310 ; 0004-6981
    DOI 10.1016/j.atmosenv.2020.117919
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Book ; Online: New Particle Formation in the Tropical Free Troposphere during CAMP2Ex

    Xiao, Qian / Zhang, Jiaoshi / Wang, Yang / Ziemba, Luke D. / Crosbie, Ewan / Winstead, Edward L. / Robinson, Claire E. / DiGangi, Joshua P. / Diskin, Glenn S. / Reid, Jeffrey S. / Schmidt, K. Sebastian / Sorooshian, Armin / Hilario, Miguel Ricardo A. / Woods, Sarah / Lawson, Paul / Stamnes, Snorre A. / Wang, Jian

    eISSN: 1680-7324

    Statistics and Impact of Emission Sources, Convective activity, and Synoptic Condition

    2023  

    Abstract: Nucleation in the free troposphere (FT) and subsequent growth of new particles represents a globally important source of cloud condensation nuclei (CCN). Whereas new particle formation (NPF) has been shown to occur frequently in the upper troposphere ... ...

    Abstract Nucleation in the free troposphere (FT) and subsequent growth of new particles represents a globally important source of cloud condensation nuclei (CCN). Whereas new particle formation (NPF) has been shown to occur frequently in the upper troposphere over tropical oceans, there have been few studies of NPF at lower altitudes over the tropical marine environment. In addition, the impact of anthropogenic emissions and biomass burning on NPF over the tropics remains poorly understood. In this study, we examine NPF in the lower and mid troposphere (3–8.5 km) over ocean and coastal regions of the Sulu Sea and Northern Subtropical Pacific Ocean in Southeast Asia using airborne measurements during the recent Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP 2 Ex). CAMP 2 Ex took place from 25 August through 5 October 2019, including both late southwest monsoon and monsoon transition. Recent NPF events, as evidenced by elevated concentrations of newly formed particles (i.e., particles of diameters between 3 and 10 nm), were observed during 4 % of the total flight time (5 out of 128 hours). The frequency of NPF increases with altitude, reaching 49 % above an altitude of 8 km. NPF was mostly observed at altitudes above 3 km and coincided with elevated relative humidity (RH), suggesting that NPF is closely associated with convective cloud outflow in conditions of low temperature and reduced pre-existing particle concentrations. Air masses are categorized into background, biomass burning-influenced, and urban-influenced air based on in-situ CO, CH 4 and O 3 measurements. NPF in background air was mostly observed above 6 km, typically accompanied by the lowest surface area among all air mass types. NPF occurred above the 0 ºC level at 5.5–7 km in air masses influenced by convectively detrained biomass burning and/or urban emissions and was enhanced by 1) scavenged primary particles; 2) elevated precursor concentrations and 3) enhanced irradiance due to cloud reflections. However, NPF was suppressed in aged ...
    Subject code 333
    Language English
    Publishing date 2023-01-03
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Book ; Online: New particle formation in the tropical free troposphere during CAMP2Ex

    Xiao, Qian / Zhang, Jiaoshi / Wang, Yang / Ziemba, Luke D. / Crosbie, Ewan / Winstead, Edward L. / Robinson, Claire E. / DiGangi, Joshua P. / Diskin, Glenn S. / Reid, Jeffrey S. / Schmidt, K. Sebastian / Sorooshian, Armin / Hilario, Miguel Ricardo A. / Woods, Sarah / Lawson, Paul / Stamnes, Snorre A. / Wang, Jian

    eISSN: 1680-7324

    statistics and impact of emission sources, convective activity, and synoptic conditions

    2023  

    Abstract: Nucleation in the free troposphere (FT) and subsequent growth of new particles represent a globally important source of cloud condensation nuclei (CCN). Whereas new particle formation (NPF) has been shown to occur frequently in the upper troposphere over ...

    Abstract Nucleation in the free troposphere (FT) and subsequent growth of new particles represent a globally important source of cloud condensation nuclei (CCN). Whereas new particle formation (NPF) has been shown to occur frequently in the upper troposphere over tropical oceans, there have been few studies of NPF at lower altitudes. In addition, the impact of urban emissions and biomass burning on the NPF in tropical marine FT remains poorly understood. In this study, we examine NPF in the lower and mid-troposphere (3–8.5 km ) over the tropical ocean and coastal region using airborne measurements during the recent Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP 2 Ex). NPF was mostly observed above 5.5 km and coincided with elevated relative humidity (RH) and reduced condensation sink (CS), suggesting that NPF occurs in convective cloud outflow. The frequency of NPF increases with altitude, reaching ∼ 50 % above 8 km . An abrupt decrease in NPF frequency coincides with early monsoon transition and is attributed to increased CS resulting from reduced convective activity and more frequent transport of aged urban plumes. Surprisingly, a large fraction of NPF events in background air were observed in the early morning, and the NPF is likely made possible by very low CS despite low actinic flux. Convectively detrained biomass-burning plumes and fresh urban emissions enhance NPF as a result of elevated precursor concentrations and scavenging of pre-existing particles. In contrast, NPF is suppressed in aged urban plumes where the reactive precursors are mostly consumed, while CS remains relatively high. This study shows a strong impact of urban and biomass-burning emissions on the NPF in tropical marine FT. The results also illustrate the competing influences of different variables and interactions among anthropogenic emissions, convective clouds, and meteorology, which lead to NPF under a variety of conditions in tropical marine environments.
    Subject code 551
    Language English
    Publishing date 2023-09-06
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article: Aerosol responses to precipitation along North American air trajectories arriving at Bermuda.

    Dadashazar, Hossein / Alipanah, Majid / Hilario, Miguel Ricardo A / Crosbie, Ewan / Kirschler, Simon / Liu, Hongyu / Moore, Richard H / Peters, Andrew J / Scarino, Amy Jo / Shook, Michael / Thornhill, K Lee / Voigt, Christiane / Wang, Hailong / Winstead, Edward / Zhang, Bo / Ziemba, Luke / Sorooshian, Armin

    Atmospheric chemistry and physics

    2021  Volume 21, Issue 21, Page(s) 16121–16141

    Abstract: North American pollution outflow is ubiquitous over the western North Atlantic Ocean, especially in winter, making this location a suitable natural laboratory for investigating the impact of precipitation on aerosol particles along air mass trajectories. ...

    Abstract North American pollution outflow is ubiquitous over the western North Atlantic Ocean, especially in winter, making this location a suitable natural laboratory for investigating the impact of precipitation on aerosol particles along air mass trajectories. We take advantage of observational data collected at Bermuda to seasonally assess the sensitivity of aerosol mass concentrations and volume size distributions to accumulated precipitation along trajectories (APT). The mass concentration of particulate matter with aerodynamic diameter less than 2.5 μm normalized by the enhancement of carbon monoxide above background (PM
    Language English
    Publishing date 2021-11-09
    Publishing country Germany
    Document type Journal Article
    ISSN 1680-7316
    ISSN 1680-7316
    DOI 10.5194/acp-21-16121-2021
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Particulate Oxalate-To-Sulfate Ratio as an Aqueous Processing Marker: Similarity Across Field Campaigns and Limitations.

    Hilario, Miguel Ricardo A / Crosbie, Ewan / Bañaga, Paola Angela / Betito, Grace / Braun, Rachel A / Cambaliza, Maria Obiminda / Corral, Andrea F / Cruz, Melliza Templonuevo / Dibb, Jack E / Lorenzo, Genevieve Rose / MacDonald, Alexander B / Robinson, Claire E / Shook, Michael A / Simpas, James Bernard / Stahl, Connor / Winstead, Edward / Ziemba, Luke D / Sorooshian, Armin

    Geophysical research letters

    2021  Volume 48, Issue 23

    Abstract: Leveraging aerosol data from multiple airborne and surface-based field campaigns encompassing diverse environmental conditions, we calculate statistics of the oxalate-sulfate mass ratio (median: 0.0217; 95% confidence interval: 0.0154-0.0296; ...

    Abstract Leveraging aerosol data from multiple airborne and surface-based field campaigns encompassing diverse environmental conditions, we calculate statistics of the oxalate-sulfate mass ratio (median: 0.0217; 95% confidence interval: 0.0154-0.0296;
    Language English
    Publishing date 2021-11-24
    Publishing country United States
    Document type Journal Article
    ZDB-ID 7403-2
    ISSN 0094-8276
    ISSN 0094-8276
    DOI 10.1029/2021gl096520
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Book ; Online: Investigating size-segregated sources of elemental composition of particulate matter in the South China Sea during the 2011 Vasco cruise

    Hilario, Miguel Ricardo A. / Cruz, Melliza T. / Cambaliza, Maria Obiminda L. / Reid, Jeffrey S. / Xian, Peng / Simpas, James B. / Lagrosas, Nofel D. / Uy, Sherdon Niño Y. / Cliff, Steve / Zhao, Yongjing

    eISSN: 1680-7324

    2020  

    Abstract: The South China Sea (SCS) is a receptor of numerous natural and anthropogenic aerosol species from throughout greater Asia. A combination of several developing countries, archipelagic and peninsular terrain, a strong Asian monsoon climate, and a host of ... ...

    Abstract The South China Sea (SCS) is a receptor of numerous natural and anthropogenic aerosol species from throughout greater Asia. A combination of several developing countries, archipelagic and peninsular terrain, a strong Asian monsoon climate, and a host of multi-scale meteorological phenomena make the SCS one of the most complex aerosol–meteorological systems in the world. However, aside from the well-known biomass burning emissions from Indonesia and Borneo, the current understanding of aerosol sources is limited, especially in remote marine environments. In September 2011, a 2-week research cruise was conducted near Palawan, Philippines, to sample the remote SCS environment. Size-segregated aerosol data were collected using a Davis Rotating Uniform size-cut Monitor (DRUM) sampler and analyzed for concentrations of 28 elements measured via X-ray fluorescence (XRF). Positive matrix factorization (PMF) was performed separately on the coarse, fine, and ultrafine size ranges to determine possible sources and their contributions to the total elemental particulate matter mass. The PMF analysis resolved six sources across the three size ranges: biomass burning, oil combustion, soil dust, a crustal–marine mixed source, sea spray, and fly ash. Additionally, size distribution plots, time series plots, back trajectories and satellite data were used in interpreting factors. The multi-technique source apportionment revealed the presence of biogenic sources such as soil dust, sea spray, and a crustal–marine mixed source. Anthropogenic sources were also identified: biomass burning, oil combustion, and fly ash. Mass size distributions showed elevated aerosol concentrations towards the end of the sampling period, which coincided with a shift of air mass back trajectories to southern Kalimantan. Covariance between coarse-mode soil dust and fine-mode biomass burning aerosols were observed. Agreement between the PMF and the linear regression analyses indicates that the PMF solution is robust. While biomass burning is indeed a key source of aerosol, this study shows the presence of other important sources in the SCS. Identifying these sources is not only key for characterizing the chemical profile of the SCS but, by improving our picture of aerosol sources in the region, also a step forward in developing our understanding of aerosol–meteorology feedbacks in this complex environment.
    Subject code 551
    Language English
    Publishing date 2020-02-04
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  9. Book ; Online: Aerosol responses to precipitation along North American air trajectories arriving at Bermuda

    Dadashazar, Hossein / Alipanah, Majid / Hilario, Miguel Ricardo A. / Crosbie, Ewan / Kirschler, Simon / Liu, Hongyu / Moore, Richard H. / Peters, Andrew J. / Scarino, Amy Jo / Shook, Michael / Thornhill, K. Lee / Voigt, Christiane / Wang, Hailong / Winstead, Edward / Zhang, Bo / Ziemba, Luke / Sorooshian, Armin

    eISSN: 1680-7324

    2021  

    Abstract: North American pollution outflow is ubiquitous over the western North Atlantic Ocean, especially in winter, making this location a suitable natural laboratory for investigating the impact of precipitation on aerosol particles along air mass trajectories. ...

    Abstract North American pollution outflow is ubiquitous over the western North Atlantic Ocean, especially in winter, making this location a suitable natural laboratory for investigating the impact of precipitation on aerosol particles along air mass trajectories. We take advantage of observational data collected at Bermuda to seasonally assess the sensitivity of aerosol mass concentrations and volume size distributions to accumulated precipitation along trajectories (APT). The mass concentration of particulate matter with aerodynamic diameter less than 2.5 µm normalized by the enhancement of carbon monoxide above background (PM <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">2.5</mn></msub><mo>/</mo><mi mathvariant="normal">Δ</mi></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="5ae6b0495bee251fbac1bfef6bb6209c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-16121-2021-ie00001.svg" width="28pt" height="14pt" src="acp-21-16121-2021-ie00001.png"/></svg:svg> CO) at Bermuda was used to estimate the degree of aerosol loss during transport to Bermuda. Results for December–February (DJF) show that most trajectories come from North America and have the highest APTs, resulting in a significant reduction (by 53 %) in PM <math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">2.5</mn></msub><mo>/</mo><mi mathvariant="normal">Δ</mi></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c8fdc99ec2b4407938f2aa5aba123896"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-16121-2021-ie00002.svg" width="28pt" height="14pt" src="acp-21-16121-2021-ie00002.png"/></svg:svg> CO under high-APT conditions ( > 13.5 mm) relative to low-APT conditions ( < 0.9 mm). Moreover, PM <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">2.5</mn></msub><mo>/</mo><mi mathvariant="normal">Δ</mi></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="19fc9097c12ca03c91427d1cc7d7775a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-16121-2021-ie00003.svg" width="28pt" height="14pt" src="acp-21-16121-2021-ie00003.png"/></svg:svg> CO was most sensitive to increases in APT up to 5 mm ( − 0.044 µg m −3 ppbv −1 mm −1 ) and less sensitive to increases in APT over 5 mm. While anthropogenic PM 2.5 constituents (e.g., black carbon, sulfate, organic carbon) decrease with high APT, sea salt, in contrast, was comparable between high- and low-APT conditions owing to enhanced local wind and sea salt emissions in high-APT conditions. The greater sensitivity of the fine-mode volume concentrations (versus coarse mode) to wet scavenging is evident from AErosol RObotic NETwork (AERONET) volume size distribution data. A combination of GEOS-Chem model simulations of the 210 Pb submicron aerosol tracer and its gaseous precursor 222 Rn reveals that (i) surface aerosol particles at Bermuda are most impacted by wet scavenging in winter and spring (due to large-scale precipitation) with a maximum in March, whereas convective scavenging plays a substantial role in summer; and (ii) North American 222 Rn tracer emissions contribute most to surface 210 Pb concentrations at Bermuda in winter ( ∼ 75 %–80 %), indicating that air masses arriving at Bermuda experience large-scale precipitation scavenging while traveling from North America. A case study flight from the ACTIVATE field campaign on 22 February 2020 reveals a significant reduction in aerosol number and volume concentrations during air mass transport off the US East Coast associated with increased cloud fraction and precipitation. These results highlight the sensitivity of remote marine boundary layer aerosol characteristics to precipitation along trajectories, especially when the air mass source is continental outflow from polluted regions like the US East Coast.
    Subject code 333 ; 511
    Language English
    Publishing date 2021-11-02
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Book ; Online: Total organic carbon and contribution from speciated organics in cloud water

    Stahl, Connor / Crosbie, Ewan / Bañaga, Paola Angela / Betito, Grace / Braun, Rachel A. / Cainglet, Zenn Marie / Cambaliza, Maria Obiminda / Cruz, Melliza Templonuevo / Dado, Julie Mae / Hilario, Miguel Ricardo A. / Leung, Gabrielle Frances / MacDonald, Alexander B. / Magnaye, Angela Monina / Reid, Jeffrey / Robinson, Claire / Shook, Michael A. / Simpas, James Bernard / Visaga, Shane Marie / Winstead, Edward /
    Ziemba, Luke / Sorooshian, Armin

    eISSN: 1680-7324

    Airborne data analysis from the CAMP2Ex field campaign

    2021  

    Abstract: This work focuses on total organic carbon (TOC) and contributing species in cloud water over Southeast Asia using a rare airborne dataset collected during NASA’s Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP 2 Ex), in which a wide ... ...

    Abstract This work focuses on total organic carbon (TOC) and contributing species in cloud water over Southeast Asia using a rare airborne dataset collected during NASA’s Cloud, Aerosol and Monsoon Processes Philippines Experiment (CAMP 2 Ex), in which a wide variety of maritime clouds were studied, including cumulus congestus, altocumulus, altostratus, and cumulus. Knowledge of TOC levels and their contributing species is needed for improved modeling of cloud processing of organics and to understand how aerosols and gases impact and are impacted by clouds. This work relies on 159 samples collected with an Axial Cyclone Cloud water Collector at altitudes of 0.2–6.8 km that had sufficient volume for both TOC and speciated organic composition analysis. Species included monocarboxylic acids (glycolate, acetate, formate, and pyruvate), dicarboxylic acids (glutarate, adipate, succinate, maleate, and oxalate), methanesulfonate (MSA), and dimethylamine (DMA). TOC values range between 0.018–13.660 ppm C with a mean of 0.902 ppm C. The highest TOC values are observed below 2 km with a general reduction aloft. An exception is samples impacted by biomass burning for which TOC remains enhanced as high as 6.5 km (7.048 ppm C). Estimated total organic matter derived from TOC contributes a mean of 30.7 % to total measured mass (inorganics + organics). Speciated organics contribute (on carbon mass basis) an average of 30.0 % to TOC in the study region, and account for an average of 10.3 % to total measured mass. The order of the average contribution of species to TOC, in decreasing contribution of carbon mass, is as follows: acetate (14.7 ± 20.5 %), formate (5.4 ± 9.3 %), oxalate (2.8 ± 4.3 %), DMA (1.7 ± 6.3 %), succinate (1.6 ± 2.4 %), pyruvate (1.3 ± 4.5 %), glycolate (1.3 ± 3.7 %), adipate (1.0 ± 3.6 %), MSA (0.1 ± 0.1 %), glutarate (0.1 ± 0.2 %), maleate (< 0.1 ± 0.1 %). Approximately 70 % of TOC remains unaccounted for, thus highlighting the complex nature of organics in the study region; samples collected in biomass burning plumes have up to 95.6 % of unaccounted TOC mass based on the species detected. Consistent with other regions, monocarboxylic acids dominate the speciated organic mass (~75 %) and are about four times in greater abundance than dicarboxylic acids. Samples are categorized into four cases based on back-trajectory history revealing source-independent similarity between the bulk contributions of monocarboxylic and dicarboxylic acids to TOC (16.03 %–23.66 % and 3.70 %–8.75 %, respectively). Furthermore, acetate, formate, succinate, glutarate, pyruvate, oxalate, and MSA are especially enhanced during biomass burning periods, attributed to peat emissions transported from Sumatra and Borneo. Lastly, dust (Ca 2+ ) and sea salt (Na + /Cl − ) tracers exhibit strong correlations with speciated organics, thus supporting how coarse aerosol surfaces interact with these water-soluble organics.
    Subject code 550 ; 333
    Language English
    Publishing date 2021-06-02
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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