ALBERT

Description: Ground motion with strong‐velocity pulses can cause significant damage to buildings and structures at certain periods; hence, knowing the period and velocity amplitude of such pulses is critical for earthquake structural engineering. However, the physical factors relating the scaling of pulse periods with magnitude are poorly understood. In this study, we investigate moderate but damaging earthquakes (⁠Mw 6–7) and characterize ground‐motion pulses using the method of Shahi and Baker (2014) while considering the potential static‐offset effects. We confirm that the within‐event variability of the pulses is large. The identified pulses in this study are mostly from strike‐slip‐like earthquakes. We further perform simulations using the frequency–wavenumber algorithm to investigate the causes of the variability of the pulse periods within and between events for moderate strike‐slip earthquakes. We test the effect of fault dips, and the impact of the asperity locations and sizes. The simulations reveal that the asperity properties have a high impact on the pulse periods and amplitudes at nearby stations. Our results emphasize the importance of asperity characteristics, in addition to earthquake magnitudes for the occurrence and properties of pulses produced by the forward directivity effect. We finally quantify and discuss within‐ and between‐event variabilities of pulse properties at short distances.

Description: Temperature and heating-induced temperature differences were measured along a chain of thermistors. SIMBA 2019T62 (a.k.a. PRIC_09_01,IRIDIUM number 300234068706290) is an autonomous instrument that was installed on drifting sea ice in the Arctic Ocean during the 1st leg of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) in October 2019. The buoy was deployed at the second year coring site of the MOSAiC central observatory with initial thicknesses of snow and ice of 0.18 and 0.80 m, respectively, on 29 October 2019. The thermistor chain was 5 m long and included 241 sensors with a regular spacing of 2 cm. The depths for the sensors are 96 to -382 cm, referring to the initial interface between snow and ice. The last sensor was used to measure the air temperature at 1 m above the initial snow surface. The resulting time series describes the evolution of temperature and temperature differences after two heating cycles of 30 and 120 s as a function of place, depth and time between 29 October 2019 and 28 July 2020 in sample intervals of 6 hours for temperature and 24 hours for temperature differences. In addition to temperature, geographic position, barometric pressure, tilt and compass were measured until 1 August 2020.

Description: One unmanned ice station (UIS) has been deployed at the L3 site (85.13ºN, 135.68ºE) of the Distributed Network (DN) of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign on 10 October 2019. The UIS is a new prototype of IMB assembled by the Polar Research Institute of China, which consists of two separate units (ice and ocean) to measure physical parameters of the air-snow-sea ice-ocean system. For the ice unit, two acoustic sensors (Campbell SR50A and Teledyne-Benthos PSA916, respectively) are used to measure the relative changes in the position of the air/snow and ice/water interfaces. Thermistors (Maxim Integrated DS28EA00) mounted at 0.03 m spacing along a 4.5-m thermistor chain were used to measure temperature profiles. Air temperature and relative humidity (Vaisala HMP155A), as well as barometric pressure (Vaisala CS106), were measured at 1.5 m height above the initial snow surface. The UIS ocean unit (CT package) consisted of five conductivity & temperature sensors (RBR duo CT), one conductivity, and temperature & depth (pressure) sensor (RBR concerto CTD). The ocean unit were used to measure upper ocean at the depths of about 5-40 m, with the initial depths of 5.4, 10.4, 15.4, 20.4, 25.4, and 40.4 m. The ice and ocean units of UIS were deployed 10 m apart. The initial ice thickness and snow depth at the buoy deployment site were 1.53 and 0.15 m, respectively. The changes in ice thickness was determined using measurements by the underwater acoustic sounder. The measuring noise of the acoustic sounder has been removed. Since the acoustic sensor at the surface was invalid very soon after the deployment, the evolution of the air/snow interface was determined using the temperature profiles. Overall, the measurement accuracy was 0.1 K for temperature, 0.03 m for the snow or ice surface, and 0.01 m for the ice bottom, respectively. After the snow cover melted over, the negative values for the snow depth indicate the onset of ice surface melt. The changes in the depths of CT sensors were estimated based on their initial depths and the depth measured by the CTD at the bottom of CT package. The measurement of the UIS ice unit lasted until 15 June 2020 when the buoy drifted to 82.28°N; while the ocean unit lasted until 28 September 2020 and finally failed at 74.09°N.

Description: Temperature and heating-induced temperature differences were measured along a chain of thermistors. SIMBA 2019T68 (a.k.a. FMI_06_01, IRIDIUM number 300234068708330) is an autonomous instrument that was installed on drifting sea ice in the Arctic Ocean during the 1st leg of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) in October 2019. The buoy was deployed at the M1site with initial thicknesses of snow and ice of 0.17 and 1.81 m, respectively, on 5 October 2019. The thermistor chain was 5 m long and included 241 sensors with a regular spacing of 2 cm. The depths for the sensors are 81 to -397 cm, referring to the initial interface between snow and ice. The last sensor was used to measure the air temperature at 1 m above the initial snow surface. The resulting time series describes the evolution of temperature and temperature differences after two heating cycles of 30 and 120 s as a function of depth and time between 5 October 2019 and 5 June 2020 in sample intervals of 6 hours for temperature and 24 hours for temperature differences. In addition to temperature, geographic position, barometric pressure, tilt and compass were measured.

Description: Alkenone concentration and radiocarbon age in 7 gobally-distributed surface sediment samples and their associated grain-size fractions. Total organic carbon (TOC) and fractional abundance of grain-size fractions from bulk sediments (Bulk%) are taken from Ausín et al. (2021). Analytical precision of Uk'37 is 0.003 units. Uk'37-SST propagated error is ±0.51℃. These parameters were measured to explore the influence of alkenone-mineral associations and hydrodynamic mineral sorting processes on alkenone proxy signals. Bulk sediment samples were fractionated into four grain-size fractions (sand (〉300-63 µm); coarse silt (63-10 µm); fine silt (10-2 µm); and clay (〈 2 µm) prior to lipid extraction and manual column chromatography to obtain a ketone fraction containing the alkenones. The concentration and distribution of C37 alkenones was analyzed using gas chromatography with flame ionization detection (GC-FID) at the Biogeoscience Group Laboratories, ETH Zürich in 2018. The ketone fractions used for determination of alkenone concentration and unsaturation were further purified for compound specific radiocarbon analysis following Ohkouchi et al. (2005). Samples, were measured as CO2 using an Elemental-Analyzer system interface coupled to a gas ion source (GIS)-equipped Minicarbon Dating System (MICADAS) at the Laboratory of Ion Beam Physics, ETH Zürich in 2018. References Ausín, B., Bruni, E., Haghipour, N., Welte, C., Bernasconi, S. M., & Eglinton, T. I. Controls on the abundance, provenance and age of organic carbon buried in continental margin sediments. Earth and Planetary Science Letters, 558, 116759, doi:10.1016/j.epsl.2021.116759, 2021. Ohkouchi, N., Xu, L., Reddy, C. M., Montluon, D., & linton, T. I. Radiocarbon dating of alkenones from marine sediments: I. Isolation Protocol Radiocarbon, 47, 401-412, doi:10.1017/S0033822200035189, 2005.

Description: We provide high-resolution surface temperature data for a better understanding of the spatial and temporal variability of sea ice surface characteristics in the Arctic winter. Surface temperature images were recorded during helicopter survey flights with the Infrared VarioCAM HD head 680 from InfraTec. The thermal infrared imaging was performed with a down-looking infrared camera installed in a helicopter. This data set includes 35 flights, which were performed, from a local up to a regional scale, during winter 2019/2020 as part of the MOSAiC expedition in the Arctic Ocean. The measurements were done along the transpolar drift from the northern Laptev Sea towards the Fram Strait between 02.10.2019 and 23.04.2020. The usual flight duration was 90 minutes with a flight altitude of about 300 m. The data set includes one file for every flight in all four different data types: (i) a series of images in NetCDF format, (ii) the displayed map in png format, as well as surface temperature maps in (iii) 1 m resolution and (iv) 5 m resolution, both in NetCDF format. The flights can be identified by the event-related Device Operation label or Flight ID. The metadata of the infrared Camera is registered in the AWI Sensor Web at the current Version under https://hdl.handle.net/10013/sensor.0542bbfb-172a-496f-9bce-b21c59cd02c9. Further information can be found in our Data Manual, linked under *Further details*.

Description: Leads (open water and thin ice) were classified in helicopter-borne thermal infrared observations. Lead classification maps, gridded in 1 m resolution, are provided for 35 flights between 02.10.2019 and 23.04.2020 during the MOSAiC expedition in the Arctic ocean. There is one file for every flight, either on a local (MOSAiC central observatory) or regional scale (MOSAiC distributed network). The flights can be identified by two campaign specific IDs (the event-related Device Operation label or Flight ID). The lead classification maps are derived from the surface temperature maps (doi:10.1594/PANGAEA.941017) as described in Thielke et al (in preparation). The 5 m resolution data (based on block averaged surface temperature) are included to provide data with a smaller file size so they are easier accessible and available for the comparison of the effect of different spatial resolutions. The binary lead classification is performed with a temperature threshold. In this data set, in addition to the lead classification maps, also the surface temperature and time-fixed surface temperature maps are included (the same data as included in the temperature maps: doi:10.1594/PANGAEA.941017). This time-fixed surface temperature is necessary to perform the classification and included for direct comparison to the lead classification result. All data are georeferenced, also as relative coordinates to the position of RV Polarstern which allows a Polarstern centered, Lagrangian view on the lead development.

Description: Temperature and heating-induced temperature differences were measured along a chain of thermistors. SIMBA 2019T64 (a.k.a. PRIC_09_03, IRIDIUM number 300234068701300) is an autonomous instrument that was installed on drifting sea ice in the Arctic Ocean during the 1st leg of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) in October 2019. The buoy was deployed at the M6 site with initial thicknesses of snow and ice of 0.16 and 1.74 m, respectively, on 10 October 2019. The thermistor chain was 5 m long and included 241 sensors with a regular spacing of 2 cm. The depths for the sensors are 68 to -410 cm, referring to the initial interface between snow and ice. The last sensor was used to measure the air temperature at 1 m above the initial snow surface. The resulting time series describes the evolution of temperature and temperature differences after two heating cycles of 30 and 120 s as a function of depth and time between 10 October 2019 and 2 August 2020 in sample intervals of 6 hours for temperature and 24 hours for temperature differences. In addition to temperature, geographic position, barometric pressure, tilt and compass were measured.

Description: Temperature and heating-induced temperature differences were measured along a chain of thermistors. SIMBA 2019T63 (a.k.a. PRIC_09_02, IRIDIUM number 300234068709320) is an autonomous instrument that was installed on drifting sea ice in the Arctic Ocean during the 1st leg of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) in October 2019. The buoy was deployed at the L2 site with initial thicknesses of snow and ice of 0.12 and 1.12 m, respectively, on 7 October 2019. The thermistor chain was 5 m long and included 241 sensors with a regular spacing of 2 cm. The depths for the sensors are 56 to -422 cm, referring to the initial interface between snow and ice. The last sensor was used to measure the air temperature at 1 m above the initial snow surface. The resulting time series describes the evolution of temperature and temperature differences after two heating cycles of 30 and 120 s as a function of depth and time between 7 October 2019 and 27 July 2020 in sample intervals of 6 hours for temperature and 24 hours for temperature differences. In addition to temperature, geographic position, barometric pressure, tilt and compass were measured.

Description: Absorbance and spectral absorption coefficient (SAC) parameters as measured by a VIPER G2 spectral transmissometer (TriOS) mounted in the sensor skid of a remotely operated vehicle (ROV) during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition between November 2019 and September 2020. Data use manufacturer calibration. The path length was 250 mm and the wavelength range 360-750 nm. More technical details can be found here: https://www.trios.de/en/viper.html.