ALBERT

Description: The Halo Microwave Package (HAMP), deployed onboard the High Altitude and LOng range research aircraft (HALO), performed measurements over the Arctic ocean and sea-ice during the HALO-(AC)³ campaign in March and April 2022. After the transfer flight (RF01) from Oberpfaffenhofen (Germany), 17 research flight (RF) days started from Kiruna, Sweden and heading northwards to the Fram Strait and central Arctic. Here, HAMP measurements were taken in different weather conditions comprising high impact synoptic events such as warm air intrusions, atmospheric rivers, cold air outbreaks or polar lows. We provide a dataset of active and passive microwave HAMP measurements, i.e. from the cloud and precipitation radar and the radiometers respectively. The radar operates at a frequency of 35 GHz while the microwave radiometer measurements comprise 25 channels in the frequency range between 22 and 190 GHz. Our dataset delivers time-series of brightness temperatures from the radiometers, and the radar reflectivity factor and linear depolarization ratio from the radar in a unified format. The unified and processed dataset provides the post-calibrated and quality-controlled measurements from both devices in a collocated temporal 1 Hz resolution applicable for joint analysis. An adherent surface mask distinguishes between three predominant overpassed surface types (land, sea, and sea-ice). The radar measurements are further unified in a vertical grid having 30 m resolution. Our unified dataset allows for wide-spread analysis of evolving arctic cloud and moisture properties over the remote Arctic ocean.

Description: During the HALO-(AC)³ campaign in March/ April 2022, in-situ particle number concentration and size distribution of ambient aerosol particles and cloud residual particles were measured using a Grimm Sky OPC (model 1.129 Sky-OPC). This data set provides the particle size distribution divided in 31 size bins between 0.25 µm and 40 µm. Particle number concentrations are pressure-corrected to standard temperature and pressure (STP). The time resolution of the instrument is 6 seconds. Each data point is given at the end of the corresponding measurement interval.

Description: This data set contains in-situ analysis of individual particles measured during HALO-(AC)³ in March/April 2022. Using the single particle aerosol mass spectrometer ALABAMA, particle size and chemical composition of single particles were analyzed onboard of the research aircraft Polar 6. The data provides time, location, particle size (if available), an integer value inlet_pos as indicator for the position of the ALABAMA inlet switch (2: CVI inlet, 4: standard aerosol inlet) as well as counts of different cluster types for each analyzed particle. The 38 clusters were determined by using a fuzzy-c-means algorithm, a method for grouping data points with similar signal pattern. The key chemical species of each cluster are given in the longname version of the cluster variables in the data files. A detailed description of the data processing will be done in an upcoming data paper.

Description: During the HALO-(AC)³ campaign performed in March/April 2022, broadband solar and thermal-infrared irradiances in the vicinity of Svalbard were measured by pairs of CMP22 (0.2-3.6 µm) and CGR4 (4.5-42 µm) radiometers (Kipp&Zonen), respectively, onboard Polar 5 and Polar 6. The data set contains time series of both upward and downward solar and thermal-infrared irradiances obtained during in total 26 research flights (13 with each aircraft). All irradiances were corrected for instrument inertia (Ehrlich and Wendisch, 2015), the solar downward irradiance additionally for the aircraft attitude (Bannehr and Schwiesow, 1993). Since the latter correction is only valid for cloud-free conditions dominated by direct illumination, both a corrected and an uncorrected version are given. A rough cloud flag is included in the data set to distinguish between situations dominated by direct and diffuse illumination. To avoid too large uncertainties, the attitude flag can be used to filter situations with aircraft attitude angles (roll, pitch) exceeding 5°. Additionally, obvious icing and large temperature gradients, which disturb the thermal equilibrium between sensor and instrument body, are flagged. The data set further contains the solar downward irradiance simulated for cloud-free conditions and the upward brightness temperature measured by the KT-19 infrared thermometer (HEITRONICS, 9.6-11.5 µm).

Description: This dataset contains the processed and raw data collected with the Backscatter Cloud Probe with Polarization Detection during the HALO-AC³ campaign in March and April 2022 with the Polar 6 Aircraft out of Longyearbyen, Svalbard. The dataset contains two kinds of data. Data to which no inversion procedure has been applied and data to which the inversion procedure has been applied. The inversion procedure is applied to account for an uneven intensity of the laser beam across the sample area and resulting undersizing effects. The inversion procedure has been discussed in Lucke et al. (2023) (doi.org/10.4271/2023-01-1485) and Beswick et al. (2014) (doi.org/10.5194/amt-7-1443-2014). All quantities which carry the suffix inv are based on the inverted data, all other properties are not. It should be noted, that the necessity of the inversion procedure remains unclear (see the previously mentioned publications). The inversion procedure could only be applied when more than 2000 particles were present over a 5 second interval. When this was not the case, the inverted data are 9999.999. The inverted data are therefore also computed from a 5s rolling average. The measurements of the BCPD are likely severely influenced by inertial separation effects, due to the proximity of the BCPD sample area to the fuselage (approx. 3cm). When ice particles are present, shattering occurs on the fuselage and artificially increases the ice number concentration. The number of ice and liquid particles listed in this data set can be useful for assessing the presence of ice and liquid particles. To estimate the number of liquid and ice particles more than 100 particles are required over a 5s interval. When this is not the case, the data are 9999.999. The number of ice and liquid particles were computed as rolling averages over 5s intervals. The sample area in case no inversion procedure is applied is 0.273 square millimeters.

Description: This dataset contains ambient concentrations of aerosol precursor vapors measured in the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. The timeseries includes a full year of sulfuric acid (SA), methanesulfonic acid (MSA), and iodic acid (IA) concentrations retrieved at a time resolution of 5 minutes between October 2019 and September 2020. The data were collected using a nitrate chemical ionization mass spectrometer (NO3-CIMS) as described by Jokinen et al. (2012). The instrument was located in the Swiss container, which was placed on the starboard side of Polarstern's bow on the D-deck during the campaign (Shupe et al., 2022). The concentration retrievals were obtained by integrating peaks from the high-resolution mass spectra for each compound of interest (either as a deprotonated ion or as its corresponding cluster with nitrate), normalizing the result with the sum of charger ions (NO3-, HNO3NO3-, (HNO3)2NO3-), and multiplying by the calibration factor (6×109 molec·cm-3) obtained from a dedicated calibration using SA. Since the instrument calibration was only performed using SA, the concentrations of MSA and IA are low limit estimations. SA was determined by peaks at mass to charge ratios (m/z) of 96.9601 Th (HSO4-) and 159.9557 Th (H2SO4NO3-), MSA was determined by m/z peaks at 94.9808 Th (CH3SO3-) and 157.9765 Th (CH3SO3HNO3-), and IA was determined by m/z peaks at 174.8898 Th (IO3-) and 237.8854 Th (HIO3NO3-). Zero measurements were performed periodically by placing a filter on the inlet of the instrument to determine the detection limit for each individual species. The detection limits were calculated as μ + 3 × σ, where µ is the average concentration and σ is the standard deviation, both of which were evaluated during filter measurements. The resulting detection limits are 8.8e4, 1.5e5, and 5.5e4 molec·cm-3 for SA, MSA, and IA, respectively. The dataset includes flags to specify the data that are below the detection limit. The influence of local pollution from the research vessel and other logistic activities was identified by applying a pollution detection algorithm (Beck et al., 2022) to particle number concentrations from a condensation particle counter (CPC3025, TSI) that was also located in the Swiss container. Periods that were potentially affected by primary pollution are flagged in the dataset. The columns in the data file include the date and time in Coordinated Universal Time (UTC); the concentration of SA, MSA, and IA in molec·cm-3; a detection limit flag for each individual species (1 = below detection limit); and a local pollution flag where the data may have influence from the vessel and logistical activities (1 = pollution was detected).

Description: Liquid water content and total water content from the Nevzorov probe, collected during the HALO-AC³ campaign out of Longyearbyen, Svalbard in April 2022. The dataset contains measurements from the three collector sensors of the Nevzorov probe. These are the cylindrical LWC sensor, the 8 mm TWC cone and the 12 mm TWC cone (for a description of the probe see doi:10.1175/1520-0426(1998)015〈1495:TNAHWL〉2.0.CO;2, doi:10.5194/egusphere-2022-647 ). Furthermore, corrected LWC and TWC values are contained in the dataset. These values are best estimates of LWC and TWC. They are computed by solving a system of equations and they consider collection efficiencies, the different latent heats of water and ice and the sensitivity of the LWC sensor to ice particles. For a description of the computation see Lucke et al. (2023) (doi:10.4271/2023-01-1485). However, for this data, the 12 mm cone was not included in the computation, as its data were deemed to be too unreliable in conditions where droplet diameters are low. NaNs are represented as 9999.999 in the dataset. The dataset only contains research flight 8 - 13. For the previous flights a problem with the probe existed and no data was recorded.

Description: Observations of the broadband solar and terrestrial, upward and downward irradiance were made by the Broadband AirCrAft RaDiometer Instrumentation (BACARDI) onboard the High Altitude LOng range research aircraft (HALO) during the HALO-(AC)³ campaign in March and April of 2022. BACARDI consists of two sets of Kipp and Zonen instruments - pyranometers (CMP-22) for the solar range (0.2 - 3.6 μm) and pyrgeometers (CGR-4) for the terrestrial range (4.5 - 42 μm). The data is provided at a measurement frequency of 10 Hz and has been corrected for dynamic temperature effects. More detailed information can be found in Ehrlich et al. (2023, https://doi.org/10.5194/amt-16-1563-2023). Observations of the downward solar irradiance are provided with and without a correction for the aircraft attitude, which corresponds to cloud-free and cloudy conditions above the aircraft. Furthermore, simulated, cloud-free downward solar irradiances are also given as a reference.