ALBERT

Description: The SOAP voyage examined air-sea interactions over the productive waters of the Chatham Rise, east of New Zealand onboard the RV Tangaroa (New Zealand National Institute of Water and Atmospheric Research, Wellington) from February 12 to March 7 (Law et al., 2017: doi:10.5194/acp-17-13645-2017). 23 seawater samples were collected throughout the voyage for the purpose of generating nascent SSA. Seawater samples were collected from the ocean surface during workboat operations (approximately 10 cm depth) or from the mixed layer (3 - 12 m depth, always less than the measured mixed layer depth) or deep water samples. Surface samples were collected in prewashed 5L PTFE bottles, subsurface measurements were colected in Niskin bottles onboard a CTD rosette. Nascent SSA was generated in-situ in a 0.45 m3 cylindrical polytetrafluoroethylene chamber housing four sintered glass filters with porosities between 16 and 250 μm (Cravigan et al., 2019: https://doi.org/10.5194/acp-2019-797). Dried and filtered compressed air was passed through the glass filters at a flow rate of 15.5 ± 3 L/min and resulting SSA was sampled from the headspace of the chamber. The volatility and hygroscopicity of nascent SSA was determined with a volatility and hygroscopicity tandem differential mobility analyser (VH-TDMA) (Johnson et al., 2004: doi:10.1016/j.jaerosci.2003.10.008, 2008: doi:10.1016/j.jaerosci.2008.05.005). A diffusion drier was used to dry the sample flow to 20 ± 5 % RH prior to characterisation by the VH-TDMA. The VH-TDMA used two TSI 3010 condensation particle counters. The aerosol sample flow rate for each scanning mobility particle sizer was 1 L/min, resulting in a total inlet flow of 2 L/min, the sheath flow for the pre-DMA, V-DMA and H-DMA were 11, 6 and 6 L/min, respectively. The dependence of HGF on RH at ambient temperature was measured for one water sample (workboat 9) to provide the deliquescence relative humidity (DRH). All VH-TDMA data were inverted using the TDMAinv algorithm (Gysel et al., 2009: doi:10.1016/j.jaerosci.2008.07.013). The seawater chlorophyll-a concentration was measured by filtering 2 litres of sample water onto GF/F Whatman filters, with immediate freezing in liquid nitrogen and subsequent analysis within 3 months of collection. Filters were ground and chlorophyll-a extracted in 90 % acetone with concentration determined by a calibrated fluorometer (Perkin-Elmer), with an analytical precision of 0.001 mg/m3 (Law et al., 2011: doi:10.1016/j.dsr2.2010.10.018).

Description: The SOAP voyage examined air-sea interactions over the productive waters of the Chatham Rise, east of New Zealand onboard the RV Tangaroa (New Zealand National Institute of Water and Atmospheric Research, Wellington) from February 12 to March 7 (Law et al., 2017: doi:10.5194/acp-17-13645-2017). 23 seawater samples were collected throughout the voyage for the purpose of generating nascent SSA. Seawater samples were collected from the ocean surface during workboat operations (approximately 10 cm depth) or from the mixed layer (3 - 12 m depth, always less than the measured mixed layer depth) or deep water samples. Surface samples were collected in prewashed 5L PTFE bottles, subsurface measurements were colected in Niskin bottles onboard a CTD rosette. Nascent SSA was generated in-situ in a 0.45 m3 cylindrical polytetrafluoroethylene chamber housing four sintered glass filters with porosities between 16 and 250 μm (Cravigan et al., 2019: https://doi.org/10.5194/acp-2019-797). Dried and filtered compressed air was passed through the glass filters at a flow rate of 15.5 ± 3 L/min and resulting SSA was sampled from the headspace of the chamber. Filters were collected for compositional analysis using transmission Fourier Transform Infra Red (FTIR) and Ion Beam analysis (IBA). The nascent SSA was sampled through a 1 μm sharp cut cyclone (SCC 2.229PM1, BGI Inc., Waltham, Massachusetts) and collected on Teflon filters, with the sample confined to deposit on a 10 mm circular area. Back filter blanks were used to characterise the contamination during handling, and before analysis samples were dehydrated to remove all water, including SSA hydrates, as described in (Frossard and Russell, 2012: doi:10.1021/es3032083). Filter samples underwent simultaneous particle induced X-ray emission (PIXE) and gamma ray emission (PIGE) analysis (Cohen et al., 2004: doi:10.1016/j.nimb.2004.01.043). Si was the only compound with blank measurements above the IBA detection limit. The measured S mass was used to calculate the SO4 mass, all S was assumed to be in the form of SO4. The filter exposed area (0.785 cm2) was used to convert inorganic areal concentrations into total mass. The inorganic mass (IM) was computed as the sum of Na, Mg, SO4, Cl, K, Ca, Zn, Br and Sr. The seawater chlorophyll-a concentration was measured by filtering 2 litres of sample water onto GF/F Whatman filters, with immediate freezing in liquid nitrogen and subsequent analysis within 3 months of collection. Filters were ground and chlorophyll-a extracted in 90 % acetone with concentration determined by a calibrated fluorometer (Perkin-Elmer), with an analytical precision of 0.001 mg/m3 (Law et al., 2011: doi:10.1016/j.dsr2.2010.10.018).

Description: The SOAP voyage examined air-sea interactions over the productive waters of the Chatham Rise, east of New Zealand onboard the RV Tangaroa (New Zealand National Institute of Water and Atmospheric Research, Wellington) from February 12 to March 7 (Law et al., 2017: doi:10.5194/acp-17-13645-2017). 23 seawater samples were collected throughout the voyage for the purpose of generating nascent SSA. Seawater samples were collected from the ocean surface during workboat operations (approximately 10 cm depth) or from the mixed layer (3 - 12 m depth, always less than the measured mixed layer depth) or deep water samples. Surface samples were collected in prewashed 5L PTFE bottles, subsurface measurements were colected in Niskin bottles onboard a CTD rosette. Nascent SSA was generated in-situ in a 0.45 m3 cylindrical polytetrafluoroethylene chamber housing four sintered glass filters with porosities between 16 and 250 μm (Cravigan et al., 2019: https://doi.org/10.5194/acp-2019-797). Dried and filtered compressed air was passed through the glass filters at a flow rate of 15.5 ± 3 L/min and resulting SSA was sampled from the headspace of the chamber. The volatility and hygroscopicity of nascent SSA was determined with a volatility and hygroscopicity tandem differential mobility analyser (VH-TDMA) (Johnson et al., 2004: doi:10.1016/j.jaerosci.2003.10.008, 2008: doi:10.1016/j.jaerosci.2008.05.005). A diffusion drier was used to dry the sample flow to 20 ± 5 % RH prior to characterisation by the VH-TDMA. The VH-TDMA was also used to calculate the organic volume fraction (Cravigan et al., 2019: https://doi.org/10.5194/acp-2019-797). The VH-TDMA used two TSI 3010 condensation particle counters. The aerosol sample flow rate for each scanning mobility particle sizer was 1 L/min, resulting in a total inlet flow of 2 L/min, the sheath flow for the pre-DMA, V-DMA and H-DMA were 11, 6 and 6 L/min, respectively. The SSA volatile fraction was computed by measuring the diameter of preselected SSA upon heating by a thermodenuder up to 500 degree C, in temperature increments of 5 degree C - 50 degree C. After heating the SSA hygroscopic growth factor at 90% RH was measured. All VH-TDMA data were inverted using the TDMAinv algorithm (Gysel et al., 2009: doi:10.1016/j.jaerosci.2008.07.013). The hygroscopic growth factor, semi-volatile organic volume fraction and low volatility organic volume fraction were determined as outlined in (Cravigan et al., 2019: doi:10.5194/acp-2019-797). The seawater chlorophyll-a concentration was measured by filtering 2 litres of sample water onto GF/F Whatman filters, with immediate freezing in liquid nitrogen and subsequent analysis within 3 months of collection. Filters were ground and chlorophyll-a extracted in 90 % acetone with concentration determined by a calibrated fluorometer (Perkin-Elmer), with an analytical precision of 0.001 mg/m3 (Law et al., 2011: doi:10.1016/j.dsr2.2010.10.018).

Description: The SOAP voyage examined air-sea interactions over the productive waters of the Chatham Rise, east of New Zealand onboard the RV Tangaroa (New Zealand National Institute of Water and Atmospheric Research, Wellington) from February 12 to March 7 (Law et al., 2017: doi:10.5194/acp-17-13645-2017). 23 seawater samples were collected throughout the voyage for the purpose of generating nascent SSA. Seawater samples were collected from the ocean surface during workboat operations (approximately 10 cm depth) or from the mixed layer (3 - 12 m depth, always less than the measured mixed layer depth) or deep water samples. Surface samples were collected in prewashed 5L PTFE bottles, subsurface measurements were colected in Niskin bottles onboard a CTD rosette. Nascent SSA was generated in-situ in a 0.45 m3 cylindrical polytetrafluoroethylene chamber housing four sintered glass filters with porosities between 16 and 250 μm (Cravigan et al., 2019: https://doi.org/10.5194/acp-2019-797). Dried and filtered compressed air was passed through the glass filters at a flow rate of 15.5 ± 3 L/min and resulting SSA was sampled from the headspace of the chamber. Filters were collected for compositional analysis using transmission Fourier Transform Infra Red (FTIR) and Ion Beam analysis (IBA). The nascent SSA was sampled through a 1 μm sharp cut cyclone (SCC 2.229PM1, BGI Inc., Waltham, Massachusetts) and collected on Teflon filters, with the sample confined to deposit on a 10 mm circular area. Back filter blanks were used to characterise the contamination during handling, and before analysis samples were dehydrated to remove all water, including SSA hydrates, as described in (Frossard and Russell, 2012: doi:10.1021/es3032083). FTIR measurements were carried out according to previous marine sampling techniques (Maria et al., 2003: doi:10.1029/2003jd003703; Russell et al., 2010: doi:10.1073/pnas.0908905107). Filter blanks were under the detection limit for the FTIR. The PM1 organic mass fraction from SSA samples collected on filters was computed from the total organic mass from FTIR analysis and the inorganic mass from ion beam analysis, as in (Cravigan et al., 2019: doi:10.5194/acp-2019-797). The uncertainty in the organic mass measured using FTIR is up to 20 % (Maria et al., 2003: doi:10.1029/2003jd003703; Russell et al., 2010: doi:10.1073/pnas.0908905107). The seawater chlorophyll-a concentration was measured by filtering 2 litres of sample water onto GF/F Whatman filters, with immediate freezing in liquid nitrogen and subsequent analysis within 3 months of collection. Filters were ground and chlorophyll-a extracted in 90 % acetone with concentration determined by a calibrated fluorometer (Perkin-Elmer), with an analytical precision of 0.001 mg/m3 (Law et al., 2011: doi:10.1016/j.dsr2.2010.10.018).

Description: Four North Atlantic Aerosol and Marine Ecosystems Study (NAAMES) field campaigns from winter 2015 through spring 2018 sampled an extensive set of oceanographic and atmospheric parameters during the annual phytoplankton bloom cycle. This unique dataset provides four seasons of open-ocean observations of wind speed, sea surface temperature (SST), seawater particle attenuation at 660 nm (cp,660, a measure of ocean particulate organic carbon), bacterial production rates, and sea-spray aerosol size distributions and number concentrations (NSSA). The NAAMES measurements show moderate to strong correlations (0.56 〈 R 〈 0.70) between NSSA and local wind speeds in the marine boundary layer on hourly timescales, but this relationship weakens in the campaign averages that represent each season, in part because of the reduction in range of wind speed by multiday averaging. NSSA correlates weakly with seawater cp,660 (R = 0.36, P

Description: The aerosol-driven radiative effects on marine low-level cloud represent a large uncertainty in climate simulations, in particular over the Southern Ocean, which is also an important region for sea spray aerosol production. Observations of sea spray aerosol organic enrichment and the resulting impact on water uptake over the remote Southern Hemisphere are scarce, and therefore the region is under-represented in existing parameterisations. The Surface Ocean Aerosol Production (SOAP) voyage was a 23 d voyage which sampled three phytoplankton blooms in the highly productive water of the Chatham Rise, east of New Zealand. In this study we examined the enrichment of organics to nascent sea spray aerosol and the modifications to sea spray aerosol water uptake using in situ chamber measurements of seawater samples taken during the SOAP voyage. Primary marine organics contributed up to 23 % of the sea spray mass for particles with diameter less than approximately 1 µm and up to 79 % of the particle volume for 50 nm diameter sea spray. The composition of the submicron organic fraction was consistent throughout the voyage and was largely composed of a polysaccharide-like component, characterised by very low alkane-to-hydroxyl-concentration ratios of approximately 0.1–0.2. The enrichment of organics was compared to the output from the chlorophyll-a-based sea spray aerosol parameterisation suggested by Gantt et al. (2011) and the OCEANFILMS (Organic Compounds from Ecosystems to Aerosols: Natural Films and Interfaces via Langmuir Molecular Surfactants) models. OCEANFILMS improved on the representation of the organic fraction predicted using chlorophyll a, in particular when the co-adsorption of polysaccharides was included; however, the model still under-predicted the proportion of polysaccharides by an average of 33 %. Nascent 50 nm diameter sea spray aerosol hygroscopic growth factors measured at 90 % relative humidity averaged 1.93±0.08 and did not decrease with increasing sea spray aerosol organic fractions. The observed hygroscopicity was greater than expected from the assumption of full solubility, particularly during the most productive phytoplankton bloom (B1), during which organic fractions were greater than approximately 0.4. The water uptake behaviour observed in this study is consistent with that observed for other measurements of phytoplankton blooms and can be partially attributed to the presence of sea salt hydrates, which lowers the sea spray aerosol hygroscopicity when the organic enrichment is low. The inclusion of surface tension effects only marginally improved the modelled hygroscopicity, and a significant discrepancy between the observed and modelled hygroscopicity at high organic volume fractions remained. The findings from the SOAP voyage highlight the influence of biologically sourced organics on sea spray aerosol composition; these data improve the capacity to parameterise sea spray aerosol organic enrichment and water uptake.

Description: The U.S. Department of Energy Atmospheric Radiation Measurement (ARM) West Antarctic Radiation Experiment (AWARE) performed comprehensive meteorological and aerosol measurements and ground-based atmospheric remote sensing at two Antarctic stations using the most advanced instrumentation available. A suite of cloud research radars, lidars, spectral and broadband radiometers, aerosol chemical and microphysical sampling equipment, and meteorological instrumentation was deployed at McMurdo Station on Ross Island from December 2015 through December 2016. A smaller suite of radiometers and meteorological equipment, including radiosondes optimized for surface energy budget measurement, was deployed on the West Antarctic Ice Sheet between 4 December 2015 and 17 January 2016. AWARE provided Antarctic atmospheric data comparable to several well-instrumented high Arctic sites that have operated for many years and that reveal numerous contrasts with the Arctic in aerosol and cloud microphysical properties. These include persistent differences in liquid cloud occurrence, cloud height, and cloud thickness. Antarctic aerosol properties are also quite different from the Arctic in both seasonal cycle and composition, due to the continent’s isolation from lower latitudes by Southern Ocean storm tracks. Antarctic aerosol number and mass concentrations are not only non-negligible but perhaps play a more important role than previously recognized because of the higher sensitivities of clouds at the very low concentrations caused by the large-scale dynamical isolation. Antarctic aerosol chemical composition, particularly organic components, has implications for local cloud microphysics. The AWARE dataset, fully available online in the ARM Program data archive, offers numerous case studies for unique and rigorous evaluation of mixed-phase cloud parameterization in climate models.