Andrea Baccarini, Julia Schmale, Josef Dommen
The size distribution of neutral and charged particles was measured using a neutral cluster and air ion spectrometer (NAIS) instrument. The concentration was corrected for diffusional losses in the inlet.
The concentration and temporal dynamics of small particles is fundamental to characterize the first step of new particle formation (NPF) and growth. Moreover, naturally charged particles and ions can provide information about the role of ion induced nucleation. Newly formed particles can grow to larger sizes where they act as cloud condensation nuclei, directly affecting the Earth radiative budget and cloud properties.
Measurements were performed on the 4th deck of icebreaker Oden during August and September 2018 along the track of the expedition. The concentration is reported as dN/dlog(Dp) per cubic centimeter in 90 seconds average.
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Citation
Andrea Baccarini, Julia Schmale, Josef Dommen (2020) Size distribution of neutral and charged particles smaller than 42 nm collected during the Arctic Ocean 2018 expedition. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/oden-ao-2018-aerosol-nais-1
References
Baccarini A, Karlsson L, Dommen J, Duplessis P, Vüllers J, Brooks IM, Saiz-Lopez A, Salter M, Tjernström M, Baltensperger U, Zieger P, Schmale J (2020) Frequent new particle formation over the high Arctic pack ice by enhanced iodine emissions. Nature Communications 11:4924. https://doi.org/10.1038/s41467-020-18551-0
Manninen HE et al. (2016) How to reliably detect molecular clusters and nucleation mode particles with Neutral cluster and Air Ion Spectrometer (NAIS). Atmos. Meas. Tech. 9:3577 – 3605. https://doi.org/10.5194/amt-9-3577-2016
Mirme S, Mirme A (2013) The mathematical principles and design of the NAIS – a spectrometer for the measurement of cluster ion and nanometer aerosol size distributions. Atmos. Meas. Tech., 6:1061 – 1071. https://doi.org/10.5194/amt-6-1061-2013
Wagner, R. et al. (2016) On the accuracy of ion measurements using a Neutral cluster and Air Ion Spectrometer. Boreal Env. Res. 21: 230–241. ISSN: 1797-2469
Data description
Raw data were collected at 1 Hz frequency and then averaged for 90 s in order to improve the signal to noise ratio. The NAIS measures sequentially neutral and charged particles, the measurement sequence was set to 90 s for each of the two measurement modes plus 30 s for a background measurement. Hence, a full measurement cycle took 210 s. The datetime is reported in the UTC timezone as yyyy-mm-dd HH:MM:SS.
Data are reported as dN/dlog(Dp), where dN is the particle number concentration per cubic centimeter per measured size bin normalized over the logarithm of the bin width. The bin width is defined as the distance between two diameters. They are spaced equally in log-space with 64 bins per decade. Charged particles were measured in a size range from 0.8 to 42 nm, whereas neutral particles were measured from 2 to 42 nm. The difference stem from the fact that corona charger ions had to be removed from the neutral particle measurements.
The NAIS tends to overestimate particle concentration due to the NAIS background noise (coming from the electrometers and affecting only low number concentrations), the inversion algorithm and the fact that the NAIS is not a single particle instrument. During this campaign, the concentration measured by the NAIS was between 1.5 and 2 times higher compared to other particle counters as reported in the two figures attached, these results are in line with previous studies, which also reported similar higher concentrations from NAIS.
The numeric column header corresponds to the starting size of each diameter bin. The last column in the dataset is a flag to separate between clean data and data that are potentially influenced by the ship exhaust: 1 indicates clean data and 2 contaminated data.
Three different files are provided, containing the neutral, the positively and the negatively charged aerosol size distributions.
The NAIS instrument was manufactured by Airel (Mirme and Mirme 2013). A characterization of the instruments when measuring neutral particles and ions is provided by Manninen et al. (2016) and by Wagner et al. (2016), respectively.
Comments
The ship track with latitude and longitude information can be found in the Navigation, meteorological and surface seawater data from the Arctic Ocean 2018 expedition data set.
The data creator ORCIDs are the following:
Data were collected during the Arctic Ocean 2018 expedition on board the Swedish icebreaker (I/B) Oden, which was organized by the Swedish Polar Research Secretariat. The observations were part of the project 'Aerosol-cloud interactions in the High Arctic' (PI Paul Zieger, Department of Environmental Science, Stockholm University; see MOCCHA project website with updates).
