The number concentration and properties of aerosol particles serving as cloud condensation nuclei (CCN) are important for understanding cloud properties, including in the tropical Atlantic marine boundary layer (MBL), where marine cumulus clouds reflect incoming solar radiation and obscure the low-albedo ocean surface. Studies linking aerosol source, composition, and water uptake properties in this region have been conducted primarily during the summertime dust transport season, despite the region receiving a variety of aerosol particle types throughout the year. In this study, we compare size-resolved aerosol chemical composition data to the hygrocopicity parameter κ derived from size-resolved CCN measurements made during the Elucidating the Role of Clouds-Circulation Coupling in Climate (EUREC4A) and Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) campaigns from January to February 2020. We observed unexpected periods of wintertime long-range transport of African smoke and dust to Barbados. During these periods, the accumulation-mode aerosol particle and CCN Number concentrations as well as the proportions of dust and smoke particles increased, whereas average κ slightly decreased (κ = 0.46 +/- 0.10) from marine background conditions (κ = 0.52 +/- 0.09) when the particles were mostly composed of marine organics and sulfate. Size-resolved chemical analysis shows that smoke particles were the major contributor to the accumulation mode during long-range transport events, indicating that smoke is mainly responsible for the observed increase in CCN number concentrations. Earlier studies conducted at Barbados have mostly focused on the role of dust in CCN, but our results show that aerosol hygroscopicity and CCN number concentrations during wintertime long-range transport events over the tropical North Atlantic are also affected by African smoke. Our findings highlight the importance of African smoke for atmospheric processes and cloud formation over the Caribbean. In the file “Dust_Mass_Conc_Royer2022” dust mass concentrations in grams per meter^3 are provided for each day of sampling. These data were used to generate Figure 2a in the manuscript. The file “Particle_Type_#fract_Royer2022” contains data obtained through CCSEM/EDX analysis and used to generate the temporal chemistry plot (Figure 4) provided in the manuscript. The data contains particle numbers for each particle type identified on stage 3 of the sampler, total particle numbers analyzed for the entire stage 3 sample, as well as particle number fractions in % values. In the file “Size-resolved_chem_Royer2022” we provide particle # and number fraction (%) values used to generate size-resolved chemistry plots in the manuscript (Figures 5a and 5b). The file includes all particle numbers and number fractions for sea salt, aged sea salt, dust+sea salt, dust, dust+smoke, smoke, sulfate, and organic particles in each size bin from 0.1 through 8.058 um during cumulative clean marine periods and CAT Event 1 as described in the manuscript. The file “K_at_0.16S_Royer2022” contains κ values calculated at 0.16% supersaturation (S) throughout the entire sampling period. These data were specifically used to generate the plot in Figure 7a. The file “CCN#_at_0.16S_Royer2022” contains cloud condensation nuclei (CCN) values calculated at 0.16% supersaturation (S) throughout the entire sampling period. These data were used to create the CCN portion of the plot in Figure 7b.
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Measurements from the RV <i>Ronald H. Brown</i> and related platforms as part of the Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC)
The Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) took place from 7 January to 11 July 2020 in the tropical North Atlantic between the eastern edge of Barbados and 51∘ W, the longitude of the Northwest Tropical Atlantic Station (NTAS) mooring. Measurements were made to gather information on shallow atmospheric convection, the effects of aerosols and clouds on the ocean surface energy budget, and mesoscale oceanic processes. Multiple platforms were deployed during ATOMIC including the NOAA RV Ronald H. Brown (RHB) (7 January to 13 February) and WP-3D Orion (P-3) aircraft (17 January to 10 February), the University of Colorado's Robust Autonomous Aerial Vehicle-Endurant Nimble (RAAVEN) uncrewed aerial system (UAS) (24 January to 15 February), NOAA- and NASA-sponsored Saildrones (12 January to 11 July), and Surface Velocity Program Salinity (SVPS) surface ocean drifters (23 January to 29 April). The RV Ronald H. Brown conducted in situ and remote sensing measurements of oceanic and atmospheric properties with an emphasis on mesoscale oceanic–atmospheric coupling and aerosol–cloud interactions. In addition, the ship served as a launching pad for Wave Gliders, Surface Wave Instrument Floats with Tracking (SWIFTs), and radiosondes. Details of measurements made from the RV Ronald H. Brown, ship-deployed assets, and other platforms closely coordinated with the ship during ATOMIC are provided here. These platforms include Saildrone 1064 and the RAAVEN UAS as well as the Barbados Cloud Observatory (BCO) and Barbados Atmospheric Chemistry Observatory (BACO). Inter-platform comparisons are presented to assess consistency in the data sets. Data sets from the RV Ronald H. Brown and deployed assets have been quality controlled and are publicly available at NOAA's National Centers for Environmental Information (NCEI) data archive (https://www.ncei.noaa.gov/archive/accession/ATOMIC-2020, last access: 2 April 2021). Point-of-contact information and links to individual data sets with digital object identifiers (DOIs) are provided herein.
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- Award ID(s):
- 1937780
- NSF-PAR ID:
- 10469791
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- EGU
- Date Published:
- Journal Name:
- Earth System Science Data
- Volume:
- 13
- Issue:
- 4
- ISSN:
- 1866-3516
- Page Range / eLocation ID:
- 1759 to 1790
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract. The number concentration and properties of aerosol particles serving ascloud condensation nuclei (CCN) are important for understanding cloudproperties, including in the tropical Atlantic marine boundary layer (MBL), where marine cumulus clouds reflect incoming solar radiation and obscure thelow-albedo ocean surface. Studies linking aerosol source, composition, andwater uptake properties in this region have been conducted primarily duringthe summertime dust transport season, despite the region receiving a varietyof aerosol particle types throughout the year. In this study, we comparesize-resolved aerosol chemical composition data to the hygroscopicityparameter κ derived from size-resolved CCN measurements made duringthe Elucidating the Role of Clouds–Circulation Coupling in Climate (EUREC4A) and Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) campaigns from January to February 2020. Weobserved unexpected periods of wintertime long-range transport of Africansmoke and dust to Barbados. During these periods, the accumulation-mode aerosol particle and CCN number concentrations as well as the proportions ofdust and smoke particles increased, whereas the average κ slightlydecreased (κ=0.46±0.10) from marine backgroundconditions (κ=0.52±0.09) when the submicron particles were mostly composed of marine organics and sulfate. Size-resolved chemicalanalysis shows that smoke particles were the major contributor to theaccumulation mode during long-range transport events, indicating that smokeis mainly responsible for the observed increase in CCN numberconcentrations. Earlier studies conducted at Barbados have mostly focused onthe role of dust on CCN, but our results show that aerosol hygroscopicity and CCN number concentrations during wintertime long-range transport events over the tropical North Atlantic are also affected by African smoke. Ourfindings highlight the importance of African smoke for atmospheric processesand cloud formation over the Caribbean.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/essd-13-1759-2021
