Ice Nucleating Particles in Northern Greenland: annual cycles, biological contribution and parameterizations

Ice nucleating particles (INPs) can initiate ice formation in clouds at temperatures above &minus;38 &deg;C through heterogeneous ice nucleation. As a result, INPs affect cloud microphysical and radiative properties, cloud life time and precipitation behavior and thereby ultimately the Earth&rsquo;s climate. Yet, little is known regarding the sources, abundance and properties of INPs especially in remote regions such as the Arctic. In this study, two-year-long INP measurements (from July 2018 to September 2020) at Villum 5 Research Station (VRS) in Northern Greenland are presented. A low-volume filter sampler was deployed to collect filter samples for off-line INP analysis. An annual cycle of INP concentration (NINP) was observed and the fraction of biogenic INPs was found to be higher in snow-free months and lower in months when the surface was snow-covered. Samples were categorized into three different types based only on the slope of their INP spectra, namely into summer, winter and mix type. For each of the types a temperature dependent INP parameterization was derived, clearly different depending on the time 10 of the year. Winter and summer type occurred only during their respective seasons and were seen 60 % of the time. The mixed type occurred in the remaining 40 % of the time throughout the year. April, May and November were found to be transition months. A case study comparing April 2019 and April 2020 was performed. The month of April was selected because a significant difference in NINP was observed during these two periods, with clearly higher NINP in April 2020. NINP in the case study period revealed no clear dependency on either meteorological parameters or different surface types which were passed 15 by the collected air masses. Overall, the results suggest that the coastal regions of Greenland were main sources of INPs in April 2019 and 2020, most likely including both local terrestrial and marine sources. In parallel to the observed differences in NINP, also a higher cloud ice fraction was observed in satellite data for April 2020, compared to April 2019.</p

Sample and droplet volume information of Ice Nucleating Particles (INP) including original files, from Villum Research Station (VRS) in Northern Greenland

Number concentration of ice nucleating particles N(INP) in the Arctic were derived from filter samples collected at Villum Research Station (VRS, Northern Greenland) during the course of two years, from July 2018 to September 2020. Each filter aimed at sampling for 3.5 days, and in total, 181 samples were retrieved for this study. Filter analysis was done with two well proven INP analysis techniques, ultimately resulting in a spectrum of N(INP) for each filter. We also included a heat treatment of the samples (1 hour at 90°C, or at 85°C for a few exceptions, due to instrumental issues). With this, one can determine the fraction of proteinaceous INP, which are of biological origin. For each filter sample, we here provide the temperature dependent measured frozen fractions (f_ice) of each filter from both instruments LINA (Leipzig Ice Nucleation Array) and INDA (Ice Nucleation Droplet Array) included in separate files (e.g. INDA2_20180716_1 for INDA; LINA_20190923_1 for LINA). Most filters underwent thermal treatment and therefore the f_ice of the treated samples is also provided in separate files (e.g. INDA2_20200622_heated_90_1h_1). For each filter sample, values of N(INP) spectra from LINA and INDA were interpolated to values at 0.1K intervals, and then the two spectra were merged. Details on this procedure can be found in Sze et al. (2023). The here presented data include all datasets (f_ice over the measured temperature range) for all samples, separately for all measurements (i.e., LINA, INDA and thermally treated INDA). A list of all these separate datasets is given, together with some details related to the sample (see the table of parameters below). Each of the datasets is separately available. For more details on the separate samples and for concentration data (given as merged spectra), refer to the related data (doi:10.1594/PANGAEA.953838)

Two years of data on Ice Nucleating Particles (INP) from Villum Research Station (VRS) in Northern Greenland

Number concentration of ice nucleating particles N(INP) in the Arctic were derived from filter samples collected at Villum Research Station (VRS, Northern Greenland) during the course of two years, from July 2018 to September 2020. Each filter aimed at sampling for 3.5 days, and in total, 181 samples were retrieved for this study. Filter analysis was done with two well proven INP analysis techniques, ultimately resulting in a spectrum of N(INP) for each filter. We also included a heat treatment of the samples (1 hour at 90°C, or at 85°C for a few exceptions, due to instrumental issues). With this, one can determine the fraction of proteinaceous INP, which are of biological origin. For each filter sample, we here provide the temperature dependent measured frozen fractions (f_ice) of each filter from both instruments LINA (Leipzig Ice Nucleation Array) and INDA (Ice Nucleation Droplet Array) included in separate files (e.g. INDA2_20180716_1 for INDA; LINA_20190923_1 for LINA). Most filters underwent thermal treatment and therefore the f_ice of the treated samples is also provided in separate files (e.g. INDA2_20200622_heated_90_1h_1). For each filter sample, values of N(INP) spectra from LINA and INDA were interpolated to values at 0.1K intervals, and then the two spectra were merged. Details on this procedure can be found in Sze et al. (2023). The here presented data includes one spectrum of INP concentrations for each sample (covering the temperature range from -4.5°C down to -30.4°C), merged from a LINA and an INDA measurement. (Hint: Due to the measurement procedure, separate spectra generally are only available over a more narrow temperature range, so empty fields are left blank by intention.) Also, additional details for each sample are available, such as start and end date of the sampling and the sampled air volume. For the basic f_ice data, refer to the related data (doi:10.1594/PANGAEA.953839)