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  1. Book ; Online: Measurement report

    Humphries, Ruhi S. / Keywood, Melita D. / Ward, Jason P. / Harnwell, James / Alexander, Simon P. / Klekociuk, Andrew R. / Hara, Keiichiro / McRobert, Ian M. / Protat, Alain / Alroe, Joel / Cravigan, Luke T. / Miljevic, Branka / Ristovski, Zoran D. / Schofield, Robyn / Wilson, Stephen R. / Flynn, Connor J. / Kulkarni, Gourihar R. / Mace, Gerald G. / McFarquhar, Greg M. /
    Chambers, Scott D. / Williams, Alastair G. / Griffiths, Alan D.

    eISSN: 1680-7324

    Understanding the seasonal cycle of Southern Ocean aerosols

    2023  

    Abstract: The remoteness and extreme conditions of the Southern Ocean and Antarctic region have meant that observations in this region are rare, and typically restricted to summertime during research or resupply voyages. Observations of aerosols outside of the ... ...

    Abstract The remoteness and extreme conditions of the Southern Ocean and Antarctic region have meant that observations in this region are rare, and typically restricted to summertime during research or resupply voyages. Observations of aerosols outside of the summer season are typically limited to long-term stations, such as Kennaook / Cape Grim (KCG; 40.7 ∘ S, 144.7 ∘ E), which is situated in the northern latitudes of the Southern Ocean, and Antarctic research stations, such as the Japanese operated Syowa (SYO; 69.0 ∘ S, 39.6 ∘ E). Measurements in the midlatitudes of the Southern Ocean are important, particularly in light of recent observations that highlighted the latitudinal gradient that exists across the region in summertime. Here we present 2 years (March 2016–March 2018) of observations from Macquarie Island (MQI; 54.5 ∘ S, 159.0 ∘ E) of aerosol (condensation nuclei larger than 10 nm, CN 10 ) and cloud condensation nuclei (CCN at various supersaturations) concentrations. This important multi-year data set is characterised, and its features are compared with the long-term data sets from KCG and SYO together with those from recent, regionally relevant voyages. CN 10 concentrations were the highest at KCG by a factor of ∼50 % across all non-winter seasons compared to the other two stations, which were similar (summer medians of 530, 426 and 468 cm −3 at KCG, MQI and SYO, respectively). In wintertime, seasonal minima at KCG and MQI were similar (142 and 152 cm −3 , respectively), with SYO being distinctly lower (87 cm −3 ), likely the result of the reduction in sea spray aerosol generation due to the sea ice ocean cover around the site. CN 10 seasonal maxima were observed at the stations at different times of year, with KCG and MQI exhibiting January maxima and SYO having a distinct February high. Comparison of CCN 0.5 data between KCG and MQI showed similar overall trends with summertime maxima and wintertime minima; however, KCG exhibited slightly ( ∼10 % ) higher concentrations in summer (medians of 158 and 145 cm ...
    Subject code 333
    Language English
    Publishing date 2023-03-29
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  2. Book ; Online: Southern Ocean latitudinal gradients of cloud condensation nuclei

    Humphries, Ruhi S. / Keywood, Melita D. / Gribben, Sean / McRobert, Ian M. / Ward, Jason P. / Selleck, Paul / Taylor, Sally / Harnwell, James / Flynn, Connor / Kulkarni, Gourihar R. / Mace, Gerald G. / Protat, Alain / Alexander, Simon P. / McFarquhar, Greg

    eISSN: 1680-7324

    2021  

    Abstract: The Southern Ocean region is one of the most pristine in the world and serves as an important proxy for the pre-industrial atmosphere. Improving our understanding of the natural processes in this region is likely to result in the largest reductions in ... ...

    Abstract The Southern Ocean region is one of the most pristine in the world and serves as an important proxy for the pre-industrial atmosphere. Improving our understanding of the natural processes in this region is likely to result in the largest reductions in the uncertainty of climate and earth system models. While remoteness from anthropogenic and continental sources is responsible for its clean atmosphere, this also results in the dearth of atmospheric observations in the region. Here we present a statistical summary of the latitudinal gradient of aerosol (condensation nuclei larger than 10 nm, CN 10 ) and cloud condensation nuclei (CCN at various supersaturations) concentrations obtained from five voyages spanning the Southern Ocean between Australia and Antarctica from late spring to early autumn (October to March) of the 2017/18 austral seasons. Three main regions of influence were identified: the northern sector (40–45 ∘ S), where continental and anthropogenic sources coexisted with background marine aerosol populations; the mid-latitude sector (45–65 ∘ S), where the aerosol populations reflected a mixture of biogenic and sea-salt aerosol; and the southern sector (65–70 ∘ S), south of the atmospheric polar front, where sea-salt aerosol concentrations were greatly reduced and aerosol populations were primarily biologically derived sulfur species with a significant history in the Antarctic free troposphere. The northern sector showed the highest number concentrations with median (25th to 75th percentiles) CN 10 and CCN 0.5 concentrations of 681 (388–839) cm −3 and 322 (105–443) cm −3 , respectively. Concentrations in the mid-latitudes were typically around 350 cm −3 and 160 cm −3 for CN 10 and CCN 0.5 , respectively. In the southern sector, concentrations rose markedly, reaching 447 (298–446) cm −3 and 232 (186–271) cm −3 for CN 10 and CCN 0.5 , respectively. The aerosol composition in this sector was marked by a distinct drop in sea salt and increase in both sulfate fraction and absolute concentrations, resulting in a substantially higher CCN <math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">0.5</mn></msub><mo>/</mo></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="20pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="1ca0f7f0cbab2293f1d1e6d5184f3377"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-12757-2021-ie00001.svg" width="20pt" height="14pt" src="acp-21-12757-2021-ie00001.png"/></svg:svg> CN 10 activation ratio of 0.8 compared to around 0.4 for mid-latitudes. Long-term measurements at land-based research stations surrounding the Southern Ocean were found to be good representations at their respective latitudes; however this study highlighted the need for more long-term measurements in the region. CCN observations at Cape Grim ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">40</mn><msup><mi/><mo>∘</mo></msup><msup><mn mathvariant="normal">39</mn><mo>′</mo></msup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="666ce17390caa2e9437e22a67b9baad6"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-12757-2021-ie00002.svg" width="34pt" height="11pt" src="acp-21-12757-2021-ie00002.png"/></svg:svg> S) corresponded with CCN measurements from northern and mid-latitude sectors, while CN 10 observations only corresponded with observations from the northern sector. Measurements from a simultaneous 2-year campaign at Macquarie Island ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M21" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">54</mn><msup><mi/><mo>∘</mo></msup><msup><mn mathvariant="normal">30</mn><mo>′</mo></msup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="34pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="0918a3ee3731f893142f18257857e8cd"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-12757-2021-ie00003.svg" width="34pt" height="11pt" src="acp-21-12757-2021-ie00003.png"/></svg:svg> S) were found to represent all aerosol species well. The southernmost latitudes differed significantly from both of these stations, and previous work suggests that Antarctic stations on the East Antarctic coastline do not represent the East Antarctic sea-ice latitudes well. Further measurements are needed to capture the long-term, seasonal and longitudinal variability in aerosol processes across the Southern Ocean.
    Subject code 333 ; 511
    Language English
    Publishing date 2021-08-30
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  3. Book ; Online: Measurement Report

    Humphries, Ruhi S. / Keywood, Melita D. / Ward, Jason P. / Harnwell, James / Alexander, Simon P. / Klekociuk, Andrew R. / Hara, Keiichiro / McRobert, Ian M. / Protat, Alain / Alroe, Joel / Cravigan, Luke T. / Miljevic, Branka / Ristovski, Zoran D. / Schofield, Robyn / Wilson, Stephen R. / Flynn, Connor J. / Kulkarni, Gourihar R. / Mace, Gerald G. / McFarquhar, Greg M. /
    Chambers, Scott D. / Williams, Alastair G. / Griffiths, Alan D.

    eISSN: 1680-7324

    Understanding the seasonal cycle of Southern Ocean aerosols

    2022  

    Abstract: The remoteness and extreme conditions of the Southern Ocean and Antarctic region have meant that observations in this region are rare, and typically restricted to summertime during research or resupply voyages. Observations of aerosols outside of the ... ...

    Abstract The remoteness and extreme conditions of the Southern Ocean and Antarctic region have meant that observations in this region are rare, and typically restricted to summertime during research or resupply voyages. Observations of aerosols outside of the summer season are typically limited to long-term stations, such as Kennaook/Cape Grim (KCG, 40.7° S, 144.7° E) which is situated in the northern latitudes of the Southern Ocean, and Antarctic research stations, such as the Japanese operated Syowa (SYO, 69.0° S, 39.6° E). Measurements in the mid-latitudes of the Southern Ocean are important, particularly in light of recent observations that highlighted the latitudinal gradient that exists across the region in summertime. Here we present two years (March 2016–March 2018) of observations from Macquarie Island (MQI, 54.5° S, 159.0° E) of aerosol (condensation nuclei larger than 10 nm, CN 10 ) and cloud condensation nuclei (CCN at various supersaturations) concentrations. This important multi-year data set is characterised, and its features are compared with the long-term data sets from KCG and SYO together with those from recent, regionally relevant voyages. CN 10 concentrations were the highest at KCG by a factor of ∼50 % across all non-winter seasons compared to the other two stations which were similar (summer medians of 530 cm -3 , 426 cm -3 and 468 cm -3 at KCG, MQI and SYO, respectively). In wintertime, seasonal minima at KCG and MQI were similar (142 cm -3 and 152 cm -3 , respectively), with SYO being distinctly lower (87 cm -3 ), likely the result of the reduction in sea spray aerosol generation due to the sea-ice ocean cover around the site. CN 10 seasonal maxima were observed at the stations at different times of year, with KCG and MQI exhibiting January maxima and SYO having a distinct February high. Comparison of CCN 0.5 data between KCG and MQI showed similar overall trends with summertime maxima and wintertime minima, however KCG exhibited slightly (∼10 %) higher concentrations in summer (medians of 158 cm ...
    Subject code 333
    Language English
    Publishing date 2022-09-07
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

  4. Article ; Online: Multi-campaign ship and aircraft observations of marine cloud condensation nuclei and droplet concentrations.

    Sanchez, Kevin J / Painemal, David / Brown, Matthew D / Crosbie, Ewan C / Gallo, Francesca / Hair, Johnathan W / Hostetler, Chris A / Jordan, Carolyn E / Robinson, Claire E / Scarino, Amy Jo / Shingler, Taylor J / Shook, Michael A / Thornhill, Kenneth L / Wiggins, Elizabeth B / Winstead, Edward L / Ziemba, Luke D / Chambers, Scott / Williams, Alastair / Humphries, Ruhi S /
    Keywood, Melita D / Ward, Jason P / Cravigan, Luke / McRobert, Ian M / Flynn, Connor / Kulkarni, Gourihar R / Russell, Lynn M / Roberts, Gregory C / McFarquhar, Greg M / Nenes, Athanasios / Woods, Sarah F / Reid, Jeffery S / Small-Griswold, Jennifer / Brooks, Sarah / Kirschler, Simon / Voigt, Christianne / Wang, Jian / Delene, David J / Quinn, Patricia K / Moore, Richard H

    Scientific data

    2023  Volume 10, Issue 1, Page(s) 471

    Abstract: In-situ marine cloud droplet number concentrations (CDNCs), cloud condensation nuclei (CCN), and CCN proxies, based on particle sizes and optical properties, are accumulated from seven field campaigns: ACTIVATE; NAAMES; ... ...

    Abstract In-situ marine cloud droplet number concentrations (CDNCs), cloud condensation nuclei (CCN), and CCN proxies, based on particle sizes and optical properties, are accumulated from seven field campaigns: ACTIVATE; NAAMES; CAMP
    Language English
    Publishing date 2023-07-20
    Publishing country England
    Document type Dataset ; Journal Article
    ZDB-ID 2775191-0
    ISSN 2052-4463 ; 2052-4463
    ISSN (online) 2052-4463
    ISSN 2052-4463
    DOI 10.1038/s41597-023-02372-z
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Book ; Online: Abundance of fluorescent biological aerosol particles at temperatures conducive to the formation of mixed-phase and cirrus clouds

    Twohy, Cynthia H. / McMeeking, Gavin R. / DeMott, Paul J. / McCluskey, Christina S. / Hill, Thomas C. J. / Burrows, Susannah M. / Kulkarni, Gourihar R. / Tanarhte, Meryem / Kafle, Durga N. / Toohey, Darin W.

    eISSN: 1680-7324

    2016  

    Abstract: Some types of biological particles are known to nucleate ice at warmer temperatures than mineral dust, with the potential to influence cloud microphysical properties and climate. However, the prevalence of these particle types above the atmospheric ... ...

    Abstract Some types of biological particles are known to nucleate ice at warmer temperatures than mineral dust, with the potential to influence cloud microphysical properties and climate. However, the prevalence of these particle types above the atmospheric boundary layer is not well known. Many types of biological particles fluoresce when exposed to ultraviolet light, and the Wideband Integrated Bioaerosol Sensor takes advantage of this characteristic to perform real-time measurements of fluorescent biological aerosol particles (FBAPs). This instrument was flown on the National Center for Atmospheric Research Gulfstream V aircraft to measure concentrations of fluorescent biological particles from different potential sources and at various altitudes over the US western plains in early autumn. Clear-air number concentrations of FBAPs between 0.8 and 12 µm diameter usually decreased with height and generally were about 10–100 L −1 in the continental boundary layer but always much lower at temperatures colder than 255 K in the free troposphere. At intermediate temperatures where biological ice-nucleating particles may influence mixed-phase cloud formation (255 K ≤ T ≤ 270 K), concentrations of fluorescent particles were the most variable and were occasionally near boundary-layer concentrations. Predicted vertical distributions of ice-nucleating particle concentrations based on FBAP measurements in this temperature regime sometimes reached typical concentrations of primary ice in clouds but were often much lower. If convection was assumed to lift boundary-layer FBAPs without losses to the free troposphere, better agreement between predicted ice-nucleating particle concentrations and typical ice crystal concentrations was achieved. Ice-nucleating particle concentrations were also measured during one flight and showed a decrease with height, and concentrations were consistent with a relationship to FBAPs established previously at the forested surface site below. The vertical distributions of FBAPs measured on five flights were also compared with those for bacteria, fungal spores, and pollen predicted from the EMAC global chemistry–climate model for the same geographic region.
    Subject code 333
    Language English
    Publishing date 2016-07-08
    Publishing country de
    Document type Book ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

    Full text online

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    Inter-library loan at ZB MED

    Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.

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