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When river water meets seawater: Insights into primary marine aerosol production

2022-02-10T00:00:00Z

Title: When river water meets seawater: Insights into primary marine aerosol production Authors: Park, Jiyeon; Jang, Jiyi; Yoon, Young Jun; Kang, Sujin; Kang, Hyo Jin; Park, Kihong; Cho, Kyung Hwa; Kim, Jung-Hyun; Dall'Osto, Manuel; Lee, Bang Yong Abstract: The impact of inorganic salts and organic matter (OM) on the production of primary marine aerosols is still under debate. To constrain their impact, we investigated primary aerosols generated by a sea-spray generator chamber using surface water samples from rivers, estuaries, and seas that were collected along salinity gradients in two temperate Korean coastal systems and one Arctic coastal system. Salinity values showed an increasing trend along the river-estuary-coastal water transition, indicating the lowest amount of inorganic salts in the river but the highest amount in the sea. In river samples, the lowest number concentration of primary aerosol particles (1.01 x 10(3) cm(-3)) was observed at the highest OM content, suggesting that low salinity controls aerosol production. Moreover, the number concentration of primary aerosols increased drastically in estuarine (1.13 x 10(4) cm(-3)) and seawater (1.35 x 10(4) cm(-3)) samples as the OM content decreased. Our results indicate that inorganic salts associated with increasing salinity play a much larger role than OM in aerosol production in river-dominated coastal systems. Laboratory studies using NaCl solution supported the conclusion that inorganic salt is a critical factor in modulating the particles produced from river water and seawater. Accordingly, this study highlights that inorganic salts are a critical factor in modulating the production of primary marine aerosols.

The ABCflux database: Arctic-boreal CO2 flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems

2022-01-21T00:00:00Z

Title: The ABCflux database: Arctic-boreal CO2 flux observations and ancillary information aggregated to monthly time steps across terrestrial ecosystems Authors: Virkkala, Anna-Maria; Natali, Susan M.; Rogers, Brendan M.; Watts, Jennifer D.; Savage, Kathleen; Connon, Sara June; Mauritz, Marguerite; Schuur, Edward A. G.; Peter, Darcy; Minions, Christina; Nojeim, Julia; Commane, Roisin; Emmerton, Craig A.; Goeckede, Mathias; Helbig, Manuel; Holl, David; Iwata, Hiroki; Kobayashi, Hideki; Kolari, Pasi; Lopez-Blanco, Efren; Marushchak, Maija E.; Mastepanov, Mikhail; Merbold, Lutz; Parmentier, Frans-Jan W.; Peichl, Matthias; Sachs, Torsten; Sonnentag, Oliver; Ueyama, Masahito; Voigt, Carolina; Aurela, Mika; Boike, Julia; Celis, Gerardo; Chae, Namyi; Christensen, Torben R.; Bret-Harte, M. Syndonia; Dengel, Sigrid; Dolman, Han; Edgar, Colin W.; Elberling, Bo; Euskirchen, Eugenie; Grelle, Achim; Hatakka, Juha; Humphreys, Elyn; Jarveoja, Jarvi; Kotani, Ayumi; Kutzbach, Lars; Laurila, Tuomas; Lohila, Annalea; Mammarella, Ivan; Matsuura, Yojiro; Meyer, Gesa; Nilsson, Mats B.; Oberbauer, Steven F.; Park, Sang-Jong; Petrov, Roman; Prokushkin, Anatoly S.; Schulze, Christopher; St Louis, Vincent L.; Tuittila, Eeva-Stiina; Tuovinen, Juha-Pekka; Quinton, William; Varlagin, Andrej; Zona, Donatella; Zyryanov, Viacheslav I. Abstract: Past efforts to synthesize and quantify the magnitude and change in carbon dioxide (CO2) fluxes in terrestrial ecosystems across the rapidly warming Arctic-boreal zone (ABZ) have provided valuable information but were limited in their geographical and temporal coverage. Furthermore, these efforts have been based on data aggregated over varying time periods, often with only minimal site ancillary data, thus limiting their potential to be used in large-scale carbon budget assessments. To bridge these gaps, we developed a standardized monthly database of Arctic-boreal CO2 fluxes (ABCflux) that aggregates in situ measurements of terrestrial net ecosystem CO2 exchange and its derived partitioned component fluxes: gross primary productivity and ecosystem respiration. The data span from 1989 to 2020 with over 70 supporting variables that describe key site conditions (e.g., vegetation and disturbance type), micrometeorological and environmental measurements (e.g., air and soil temperatures), and flux measurement techniques. Here, we describe these variables, the spatial and temporal distribution of observations, the main strengths and limitations of the database, and the potential research opportunities it enables. In total, ABCflux includes 244 sites and 6309 monthly observations; 136 sites and 2217 monthly observations represent tundra, and 108 sites and 4092 observations represent the boreal biome. The database includes fluxes estimated with chamber (19 % of the monthly observations), snow diffusion (3 %) and eddy covariance (78 %) techniques. The largest number of observations were collected during the climatological summer (June-August; 32 %), and fewer observations were available for autumn (September-October; 25 %), winter (December-February; 18 %), and spring (March-May; 25 %). ABCflux can be used in a wide array of empirical, remote sensing and modeling studies to improve understanding of the regional and temporal variability in CO2 fluxes and to better estimate the terrestrial ABZ CO2 budget. ABCflux is openly and freely available online (Virkkala et al., 2021b, https://doi.org/10.3334/ORNLDAAC/1934).

Relationship between cloud condensation nuclei (CCN) concentration and aerosol optical depth in the Arctic region

2021-12-15T00:00:00Z

Title: Relationship between cloud condensation nuclei (CCN) concentration and aerosol optical depth in the Arctic region Authors: Ahn, Seo H.; Yoon, Y. J.; Choi, T. J.; Lee, J. Y.; Kim, Y. P.; Lee, B. Y.; Ritter, C.; Aas, W.; Krejci, R.; Strom, J.; Tunved, P.; Jung, Chang H. Abstract: To determine the direct and indirect effects of aerosols on climate, it is important to know the spatial and temporal variations in cloud condensation nuclei (CCN) concentrations. Although many types of CCN measurements are available, extensive CCN measurements are challenging because of the complexity and high operating cost, especially in remote areas. As aerosol optical depth (AOD) can be readily observed by remote sensing, many attempts have been made to estimate CCN concentrations from AOD. In this study, the CCN-AOD relationship is parameterized based on CCN ground measurements from the Zeppelin Observatory (78.91 degrees N, 11.89 degrees E, 474 m asl) in the Arctic region. The AOD measurements were obtained from the Ny-Alesund site (78.923 degrees N, 11.928 degrees E) and Modern-Era Retrospective Analysis for Research and Applications, Version 2 reanalysis. Our results show a CCN-AOD correlation with a coefficient of determination R-2 of 0.59. Three additional estimation models for CCN were presented based on the following data: (i) in situ aerosol chemical composition, (ii) in situ aerosol optical properties, and (iii) chemical composition of AOD obtained from reanalysis data. The results from the model using in situ aerosol optical properties reproduced the observed CCN concentration most efficiently, suggesting that the contribution of BC to CCN concentration should be considered along with that of sulfate.

Time-lapse electrical resistivity tomography and ground penetrating radar mapping of the active layer of permafrost across a snow fence in Cambridge Bay, Nunavut Territory, Canada: correlation interpretation using vegetation and meteorological data

2021-12-01T00:00:00Z

Title: Time-lapse electrical resistivity tomography and ground penetrating radar mapping of the active layer of permafrost across a snow fence in Cambridge Bay, Nunavut Territory, Canada: correlation interpretation using vegetation and meteorological data Authors: Kim, KwanSoo; Lee, Joohan; Ju, Hyeontae; Jung, Ji Young; Chae, Namyi; Chi, Junhwa; Kwon, Min Jung; Lee, Bang Yong; Wagner, Johann; Kim, Ji-Soo Abstract: The active layer thickness (ALT) is a key parameter for permafrost studies. Changes in the ALT are affected mainly by air and ground temperatures, physical and thermal properties of the surface and subsurface materials, soil moisture, vegetation, and the duration and thickness of snow cover. Ground penetrating radar (GPR) and electrical resistivity tomography (ERT) were employed across a snow fence during the thawing season to delineate and monitor the active layer of permafrost in Cambridge Bay, Nunavut, Canada. The variation of the ALT is well captured by the high-resolution time-lapse radargram. At the position of the fence, the active layer thickens over the thawing period from 0.5 m depth at the beginning to 1.0 m depth at the end. The active layer is thicker in the pre-fence area (C zone) than in the post-fence area (H zone). As the air temperature increases with time, the difference in thickness between the two zones decreases, eventually becoming almost equal. Changes in the ALT are represented in the ERT by low resistivities (< 200 omega m), which decrease gradually with time. This occurs most significantly in the H zone due to the rapidly increasing temperature in the absence of snow cover. The electrical resistivity structure of the active layer is well correlated with the vegetation activity, as measured by the normalized difference vegetation index, air/ground temperatures, soil moisture, snow cover, and snow accumulation controlled by the fence. Geophysical data interpretation and correlation schemes with vegetation and meteorological data explored in this paper can be applied to monitor the active layer, which is expected to thin during the freezing season.