Dataset: Atmospheric ice nucleating particle concentrations at Monte Baldo (Italy) observed during the DECIPHER campaign and the TEAMx programme in summer 2025, processed data, University of Basel

1. Overview and short description of dataset The dataset comprises two files containing (1) cumulative and (2) differential concentrations of atmospheric ice nucleating particles (INPs) sampled in summer 2025 at a mountain slope in the Italian Pre-Alps (Monte Baldo, 45° 39’ 57.6’’ N, 10° 49’ 19.0’’ E, 1390 m a. s. l.) during the DECIPHER campaign (https://sites.google.com/unitn.it/decipherproject/home-page) and as part of the TEAMx programme (https://www.teamx-programme.org/). The first set of samples (n = 51) was acquired between 2025-06-25 and 2025-07-04 and the second set of samples (n = 33) between 2025-09-09 and 2025-09-16. Aerosol particles were collected 2 m a. g. l. on quartz fiber filters with an effective filter diameter of 38.5 mm at an average air flow rate of 17 L min-1. The concentration of INPs active between -4 °C and -14 °C was quantified in 1-K steps in droplet freezing assays conducted on circular filter cut-outs immersed in 100 µL of ultrapure water. All tubes containing the immersed filter subsamples were analyzed three consecutive times: initially untreated, following heating at 50 °C, and subsequently 95 °C. Cumulative and differential INP concentrations were calculated according to Vali (1971) [Vali, G.: Quantitative Evaluation of Experimental Results on the Heterogeneous Freezing Nucleation of Supercooled Liquids, J. Atmos. Sci., 28, 402-409, https://doi.org/10.1175/1520-0469(1971)028<0402:QEOERA>2.0.CO;2] and Vali (2019) [Vali, G.: Revisiting the differential freezing nucleus spectra derived from drop-freezing experiments: methods of calculation, applications, and confidence limits, Atmos. Meas. Tech., 12, 1219-1231, https://doi.org/10.5194/amt-12-1219-2019, 2019]. 2. Data format Tab-delimited text files, UTF-8 encoded, without embedded metadata. 3. List of variables and derived parameters with units Variables filter_type: two categories - sample, field blank filter_name: unique name for each filter sampling_date: YYYY-MM-DD sampling_interval_start_time_[UTC]: HH:MM [UTC] sampling_interval_end_time_[UTC]: HH:MM [UTC] sampling_duration_[min]: sampling duration [minutes] sampled_air_volume_local_conditions_[m3]: air volume filtered per sample, local conditions [m3] circle_diameter_[mm]: diameter of circular filter cut-out subsamples analyzed in droplet freezing assay [mm] n_total_droplets: total number of aliquots analysed per filter in droplet freezing assay heat_treatment_[°C]: three categories – none, 50 [°C], and 95 [°C] temperature_[°C]: temperature in droplet freezing assay [°C] midpoint_temperature_interval_[°C]: midpoint temperature of 1-K wide temperature interval in droplet freezing assay [°C] n_frozen_droplets: number of frozen droplets at temperature_[°C] in droplet freezing assay comment: times indicated in the comment column refer to local time Derived parameters K(T)_[m-3]: Cumulative INP concentration at temperature_[°C] [INP m-3], calculated according to Vali (1971) [Vali, G.: Quantitative Evaluation of Experimental Results on the Heterogeneous Freezing Nucleation of Supercooled Liquids, J. Atmos. Sci., 28, 402-409, https://doi.org/10.1175/1520-0469(1971)028<0402:QEOERA>2.0.CO;2] k(T)_[m-3]: Differential concentration of INPs activated in 1-K wide temperature interval with midpoint temperature midpoint_temperature_interval_[°C] [INP m-3], calculated according to Vali (2019) [Vali, G.: Revisiting the differential freezing nucleus spectra derived from drop-freezing experiments: methods of calculation, applications, and confidence limits, Atmos. Meas. Tech., 12, 1219-1231, https://doi.org/10.5194/amt-12-1219-2019, 2019] 4. Data Sharing Policy within DECIPHER 4.1 Data Types Two data types are envisioned, namely Raw Data and Processed Data. The submission of both data types is not mandatory. "Raw Data" consists of the dataset as measured by the sensor. Data manipulation by the curators must be kept to a minimum, i.e., converting the file format and including metadata. Curators must include the tag "Raw Data" in the title of the dataset to refer to this data type. "Processed Data" consists of the dataset after manipulation through a documented, literature-compliant procedure of data processing, including data cleaning, quality control, and averaging. The procedure must be documented in the dataset description page. Curators must include the tag "Processed Data" in the title of the dataset to refer to this data type. 4.2 Internal Use Datasets will be initially accessible only to the partners who contributed measurements on Monte Baldo. The agreement between partners for the usage of other’s datasets is to propose coauthorship to the respective owners. The requirements for public data use depend on the level of data processing, whether raw or processed: The use of "Raw Data" by the project consortium is bound to a proper crediting of the dataset, using the reference reported on the dataset page. For the first 6 months after the dataset's publication, co-authorship proposals must be made to the data owners. Beyond this initial period, co-authorship is no longer mandatory, but users are encouraged to offer it to the curators. The use of "Processed Data" by the project consortium is bound to a proper crediting of the dataset, using the reference reported on the dataset page. Users of the processed data must offer co-authorship to the data curators. 5. Data Sharing and Public Data Use within TEAMx Complying with the TEAMx data management plan: “Any use of TEAMx data products, during or after the embargo period, must include an acknowledgement (i.e., citation) of the source and the data provider. Data users must inform the respective data providers if a data product is to be shared with other parties via journal articles, presentations, and research proposals. If the data product constitutes a substantial part of the work, the data provider should be offered co-authorship and the opportunity to collaborate (both during and after the embargo period). In the case of co-authorship, an additional acknowledgement of the data provider is not required.” Complying with the TEAMx data management plan and the DECIPHER data sharing policy, the use of data by the project consortium is bound to a proper crediting of the dataset, using the reference reported on the dataset page. TEAMx and DECIPHER project partners using processed data must offer co-authorship to the data curators.