Sea ice bulk density estimates during the MOSAiC freezing season from October 2019 to April 2020

MOSAiC: the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. Assuming hydrostatic equilibrium, we integrated and adjusted sea ice thickness and snow depth data from an IMB array (comprising 15 buoys), high-resolution along-track freeboard data from airborne laser scanning (ALS) and the Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) measurements, as well as snow bulk density data from snow pits, to estimate the ice bulk density (IBD) within the MOSAiC DN (defined as the area within 50 km of Polarstern) during the MOSAiC freezing season from late October 2019 to late April 2020 (Regional buoy sites). Additionally, we also provided core-based IBD data from the MOSAiC Main Coring Sites (MCS), derived using the weighing method (MCS-FYI and MCS-SYI). Due to the challenges in reconciling spatially non-overlapping observations, we implemented two alternative approaches—Regional Case 1 and Regional Case 2—to further upscale the hydrostatic equilibrium-based IBD retrievals within the MOSAiC DN. Variable Details: Note that all density results are in kilograms per cubic metre. [Time]: covering the period from 5 October 2019 to 30 April 2020 in the format yyyyMMdd. [Longitude] & [Latitude]: characterizing the daily position for the MOSAiC Central Observatory (CO). [Reg_buoy_DN]: Estimated mean sea ice bulk density at the buoy siteswithin a radius of ~50 km from CO (DN scale). [Reg_buoy_DN_Unc1]: Uncertainty of [Reg_buoy_DN] resulting from the input parameters, calculated using the Gaussian error propagation method. [Reg_buoy_DN_Unc2]: Uncertainty of [Reg_buoy_DN] resulting from the introduced empirical adjustment coefficient, characterised using the mean absolute difference of multiple freeboard estimates. [Reg_buoy_Lsite]: Estimated mean sea ice bulk density at the buoy sites within a radius of ~25 km from CO (Lsite scale). [Reg_buoy_Lsite_Unc1]: Uncertainty of [Reg_buoy_Lsite] resulting from the input parameters, calculated using the Gaussian error propagation method. [Reg_buoy_Lsite_Unc2]: Uncertainty of [Reg_buoy_Lsite] resulting from the introduced empirical adjustment coefficient, characterized using the mean absolute difference of multiple freeboard estimates. [Reg_buoy_DL]: Mean value of [Reg_buoy_DN] and [Reg_buoy_Lsite], representing regional buoy estimates of IBD within the MOSAiC DN. [Reg_buoy_DL_Unc1]: Uncertainty of [Reg_buoy_DL] resulting from the input parameters, calculated using the Gaussian error propagation method. [Reg_buoy_DL_Unc2]: Uncertainty of [Reg_buoy_DL] resulting from the introduced empirical adjustment coefficient, characterized using the mean absolute difference of multiple freeboard estimates. [Reg_case1_DN]: Mean IBD value for typical ice conditions at the DN scale, calculated using the integration of multi-source observations. [Reg_case2_DN]: Mean IBD value for typical ice conditions at the DN scale, calculated using initial values from large-scale observations and trend extrapolation. [Loc_MCS_FYI]: Local-scale core-based bulk density derived from the main first-year coring sites (MCS-FYI) during MOSAiC. [Loc_MCS_SYI]: Local-scale core-based bulk density derived from the main second-year coring sites (MCS-SYI) during MOSAiC. The density of these ice cores was measured in a freezing laboratory at an ambient temperature of –15 °C using the hydrostatic weighing method, achieving a relatively low uncertainty of only 0.2% (Pustogvar and Kulyakhtin, 2016). Pustogvar, A. and Kulyakhtin, A.: Sea ice density measurements. Methods and uncertainties, Cold Regions Science and Technology, 131, 46-52, https://doi.org/10.1016/j.coldregions.2016.09.001, 2016. Relevant datasets: Sea ice mass balance buoys (IMBs): sea ice thickness and snow depth SIMBA buoy measurements are available from PANGAEA: https://doi.org/10.1594/PANGAEA.938244. SIMB buoy measurements are available from the Arctic Data Center: https://doi.org/10.18739/A20Z70Z01. Lei, R., Cheng, B., Hoppmann, M., and Zuo, G.: Snow depth and sea ice thickness derived from the measurements of SIMBA buoys deployed in the Arctic Ocean during the Legs 1a, 1, and 3 of the MOSAiC campaign in 2019-2020, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.938244, 2021. Perovich, D., Raphael, I., Moore, R., Clemens-Sewall, D., Polashenski, C., and Planck, C.: Measurements of ice mass balance and temperature from autonomous Seasonal Ice Mass Balance buoys in the Arctic Ocean, 2019-2020, Arctic Data Center [data set], https://doi.org/10.18739/A20Z70Z01, 2022. Airborne laser scanning (ALS): sea ice total freeboard (sea ice freeboard + snow depth) Airborne laser scanning measurements during MOSAiC are available from PANGAEA: https://doi.org/10.1594/PANGAEA.950896. Hutter, N., Hendricks, S., Jutila, A., Birnbaum, G., von Albedyll, L., Ricker, R., and Haas, C.: Gridded segments of sea-ice or snow surface elevation and freeboard from helicopter-borne laser scanner during the MOSAiC expedition, version 1. PANGAEA [data set], https://doi.org/10.1594/PANGAEA.950339, 2023. Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): sea ice total freeboard (sea ice freeboard + snow depth) ICESat-2 ATL10 total freeboard data (version 6, latest version) are available from NSIDC: https://doi.org/10.5067/ATLAS/ATL10.006. Kwok, R., Petty, A., Cunningham, G., Markus, T., Hancock, D., Ivanoff, A., Wimert, J., Bagnardi, M., and Kurtz, N.: ATLAS/ICESat-2 L3A Sea Ice Freeboard, Version 6, National Snow and Ice Data Center, Boulder, Colorado, USA [data set], https://doi.org/10.5067/ATLAS/ATL10.006, 2023. Snow pits: snow density Snow pit data collected during the MOSAiC expedition are available from PANGAEA: https://doi.org/10.1594/PANGAEA.940214. Macfarlane, A. R., Schneebeli, M., Dadic, R., Wagner, D. N., Arndt, S., Clemens-Sewall, D., Hämmerle, S., Hannula, H.-R., Jaggi, M., Kolabutin, N., Krampe, D., Lehning, M., Matero, I., Nicolaus, M., Oggier, M., Pirazzini, R., Polashenski, C., Raphael, I., Regnery, J., Shimanchuck, E., Smith, M. M., and Tavri, A.: Snowpit snow density cutter profiles measured during the MOSAiC expedition, PANGAEA [data set], https://doi.org/10.1594/PANGAEA.940214, 2022. Transects: sea ice thickness and snow depth Transect data collected during MOSAiC are available from PANGAEA: https://doi.org/10.1594/PANGAEA.937781. Itkin, P., Webster, M., Hendricks, S., Oggier, M., Jaggi, M., Ricker, R., Arndt, S., Divine, D. V., von Albedyll, L., Raphael, I., Rohde, J., and Liston, G. E.: Magnaprobe snow and melt pond depth measurements from the 2019-2020 MOSAiC expedition. PANGAEA [data set], https://doi.org/10.1594/PANGAEA.937781, 2021. Ice cores: sea ice density Ice core data collected from the MOSAiC Main Coring Sites are available from PANGAEA: https://doi.org/10.1594/PANGAEA.956732 (MCS-FYI) and https://doi.org/10.1594/PANGAEA.959830 (MCS-SYI). Oggier, M., Salganik, E., Whitmore, L., Fong, A. A., Hoppe, C. J. M., Rember, R., Høyland, K. V., Divine, D. V., Gradinger, R., Fons, S. W., Abrahamsson, K., Aguilar-Islas, A. M., Angelopoulos, M., Arndt, S., Balmonte, J. P., Bozzato, D., Bowman, J. S., Castellani, G., Chamberlain, E., Creamean, J., D'Angelo, A., Damm, E., Dumitrascu, A., Eggers, S. L., Gardner, J., Grosfeld, L., Haapala, J., Immerz, A., Kolabutin, N., Lange, B. A., Lei, R., Marsay, C. M., Maus, S., Müller, O., Olsen, L. M., Nuibom, A., Ren, J., Rinke, A., Sheikin, I., Shimanchuk, E., Snoeijs-Leijonmalm, P., Spahic, S., Stefels, J., Torres-Valdés, S., Torstensson, A., Ulfsbo, A., Verdugo, J., Vortkamp, M., Wang, L., Webster, M., Wischnewski, L., and Granskog, M. A.: First-year sea-ice salinity, temperature, density, oxygen and hydrogen isotope composition from the main coring site (MCS-FYI) during MOSAiC legs 1 to 4 in 2019/2020. PANGAEA [data set], https://doi.org/10.1594/PANGAEA.956732, 2023. Oggier, M., Salganik, E., Whitmore, L., Fong, A. A., Hoppe, C. J. M., Rember, R., Høyland, K. V., Gradinger, R., Divine, D. V., Fons, S. W., Abrahamsson, K., Aguilar-Islas, A. M., Angelopoulos, M., Arndt, S., Balmonte, J. P., Bozzato, D., Bowman, J. S., Castellani, G., Chamberlain, E., Creamean, J., D'Angelo, A., Damm, E., Dumitrascu, A., Eggers, L., Gardner, J., Grosfeld, L., Haapala, J., Immerz, A., Kolabutin, N., Lange, B. A., Lei, R., Marsay, C. M., Maus, S., Olsen, L. M., Müller, O., Nuibom, A., Ren, J., Rinke, A., Sheikin, I., Shimanchuk, E., Snoeijs-Leijonmalm, P., Spahic, S., Stefels, J., Torres-Valdés, S., Torstensson, A., Ulfsbo, A., Verdugo, J., Vortkamp, M., Wang, L., Webster, M., Wischnewski, L., and Granskog, M. A.: Second-year sea-ice salinity, temperature, density, oxygen and hydrogen isotope composition from the main coring site (MCS-SYI) during MOSAiC legs 1 to 4 in 2019/2020. PANGAEA [data set], https://doi.org/10.1594/PANGAEA.959830, 2023.MOSAiC：北极气候多学科漂流观测站（Multidisciplinary drifting Observatory for the Study of Arctic Climate, MOSAiC）科考计划。 本研究基于静力学平衡假设，整合并校正了由15个浮标组成的冰质量平衡浮标（Ice Mass Balance buoys, IMBs）阵列的海冰厚度与雪深数据、机载激光扫描（Airborne Laser Scanning, ALS）获取的高分辨率沿轨干舷数据，以及冰云与陆地高程卫星-2（Ice, Cloud, and land Elevation Satellite-2, ICESat-2）的观测数据，同时结合雪坑获取的雪体密度数据，以估算2019年10月下旬至2020年4月下旬MOSAiC结冰季期间，MOSAiC DN（定义为距离极星号（Polarstern）50公里范围内的区域）内的海冰体密度（Ice Bulk Density, IBD），对应区域浮标站点。此外，本研究还提供了来自MOSAiC主取芯站点（MOSAiC Main Coring Sites, MCS）的岩芯基海冰体密度数据，该数据通过称重法获取，分为MCS-FYI（第一年期海冰取芯站点）与MCS-SYI（第二年期海冰取芯站点）两类。鉴于空间非重叠观测的协调难度，本研究采用两种替代方案——区域案例1（Regional Case 1）与区域案例2（Regional Case 2），以进一步将基于静力学平衡的海冰体密度反演结果尺度升级至MOSAiC DN区域。 ### 变量详情 请注意所有密度结果的单位均为千克每立方米。 [Time]：覆盖2019年10月5日至2020年4月30日，格式为yyyyMMdd。 [Longitude]与[Latitude]：表征MOSAiC中央观测站（MOSAiC Central Observatory, CO）的每日位置。 [Reg_buoy_DN]：以MOSAiC中央观测站为中心、半径约50公里范围内的浮标站点处估算的平均海冰体密度（DN尺度）。 [Reg_buoy_DN_Unc1]：由输入参数带来的[Reg_buoy_DN]的不确定性，通过高斯误差传播法计算得到。 [Reg_buoy_DN_Unc2]：由引入的经验校正系数带来的[Reg_buoy_DN]的不确定性，以多个干舷估算结果的平均绝对差值表征。 [Reg_buoy_Lsite]：以MOSAiC中央观测站为中心、半径约25公里范围内的浮标站点处估算的平均海冰体密度（Lsite尺度）。 [Reg_buoy_Lsite_Unc1]：由输入参数带来的[Reg_buoy_Lsite]的不确定性，通过高斯误差传播法计算得到。 [Reg_buoy_Lsite_Unc2]：由引入的经验校正系数带来的[Reg_buoy_Lsite]的不确定性，以多个干舷估算结果的平均绝对差值表征。 [Reg_buoy_DL]：[Reg_buoy_DN]与[Reg_buoy_Lsite]的平均值，代表MOSAiC DN区域内浮标基海冰体密度的区域估算结果。 [Reg_buoy_DL_Unc1]：由输入参数带来的[Reg_buoy_DL]的不确定性，通过高斯误差传播法计算得到。 [Reg_buoy_DL_Unc2]：由引入的经验校正系数带来的[Reg_buoy_DL]的不确定性，以多个干舷估算结果的平均绝对差值表征。 [Reg_case1_DN]：通过多源观测数据整合计算得到的DN尺度下典型冰情平均海冰体密度。 [Reg_case2_DN]：通过大规模观测初始值结合趋势外推法计算得到的DN尺度下典型冰情平均海冰体密度。 [Loc_MCS_FYI]：MOSAiC科考期间，来自主第一年期海冰取芯站点（MCS-FYI）的局域尺度岩芯基海冰体密度。 [Loc_MCS_SYI]：MOSAiC科考期间，来自主第二年期海冰取芯站点（MCS-SYI）的局域尺度岩芯基海冰体密度。 上述冰芯的密度于–15 °C的恒温冷冻实验室中通过静水称重法测量，不确定性仅为0.2%，精度较高（Pustogvar和Kulyakhtin, 2016）。 参考文献：Pustogvar, A. and Kulyakhtin, A.: Sea ice density measurements. Methods and uncertainties, Cold Regions Science and Technology, 131, 46-52, https://doi.org/10.1016/j.coldregions.2016.09.001, 2016. ### 相关数据集 #### 1. 冰质量平衡浮标（Ice Mass Balance buoys, IMBs）：海冰厚度与雪深 SIMBA浮标测量数据可从PANGAEA获取：https://doi.org/10.1594/PANGAEA.938244。 SIMB浮标测量数据可从北极数据中心获取：https://doi.org/10.18739/A20Z70Z01。 Lei, R., Cheng, B., Hoppmann, M., and Zuo, G.: Snow depth and sea ice thickness derived from the measurements of SIMBA buoys deployed in the Arctic Ocean during the Legs 1a, 1, and 3 of the MOSAiC campaign in 2019-2020, PANGAEA [数据集], https://doi.org/10.1594/PANGAEA.938244, 2021. Perovich, D., Raphael, I., Moore, R., Clemens-Sewall, D., Polashenski, C., and Planck, C.: Measurements of ice mass balance and temperature from autonomous Seasonal Ice Mass Balance buoys in the Arctic Ocean, 2019-2020, Arctic Data Center [数据集], https://doi.org/10.18739/A20Z70Z01, 2022. #### 2. 机载激光扫描（Airborne Laser Scanning, ALS）：海冰总干舷（海冰干舷+雪深） MOSAiC科考期间的机载激光扫描测量数据可从PANGAEA获取：https://doi.org/10.1594/PANGAEA.950896。 Hutter, N., Hendricks, S., Jutila, A., Birnbaum, G., von Albedyll, L., Ricker, R., and Haas, C.: Gridded segments of sea-ice or snow surface elevation and freeboard from helicopter-borne laser scanner during the MOSAiC expedition, version 1. PANGAEA [数据集], https://doi.org/10.1594/PANGAEA.950339, 2023. #### 3. 冰云与陆地高程卫星-2（Ice, Cloud, and land Elevation Satellite-2, ICESat-2）：海冰总干舷（海冰干舷+雪深） ICESat-2 ATL10总干舷数据（版本6，最新版本）可从美国国家冰雪数据中心（National Snow and Ice Data Center, NSIDC）获取：https://doi.org/10.5067/ATLAS/ATL10.006。 Kwok, R., Petty, A., Cunningham, G., Markus, T., Hancock, D., Ivanoff, A., Wimert, J., Bagnardi, M., and Kurtz, N.: ATLAS/ICESat-2 L3A Sea Ice Freeboard, Version 6, National Snow and Ice Data Center, Boulder, Colorado, USA [数据集], https://doi.org/10.5067/ATLAS/ATL10.006, 2023. #### 4. 雪坑：雪密度 MOSAiC科考期间采集的雪坑数据可从PANGAEA获取：https://doi.org/10.1594/PANGAEA.940214。 Macfarlane, A. R., Schneebeli, M., Dadic, R., Wagner, D. N., Arndt, S., Clemens-Sewall, D., Hämmerle, S., Hannula, H.-R., Jaggi, M., Kolabutin, N., Krampe, D., Lehning, M., Matero, I., Nicolaus, M., Oggier, M., Pirazzini, R., Polashenski, C., Raphael, I., Regnery, J., Shimanchuck, E., Smith, M. M., and Tavri, A.: Snowpit snow density cutter profiles measured during the MOSAiC expedition, PANGAEA [数据集], https://doi.org/10.1594/PANGAEA.940214, 2022. #### 5. 断面测量：海冰厚度与雪深 MOSAiC科考期间采集的断面测量数据可从PANGAEA获取：https://doi.org/10.1594/PANGAEA.937781。 Itkin, P., Webster, M., Hendricks, S., Oggier, M., Jaggi, M., Ricker, R., Arndt, S., Divine, D. V., von Albedyll, L., Raphael, I., Rohde, J., and Liston, G. E.: Magnaprobe snow and melt pond depth measurements from the 2019-2020 MOSAiC expedition. PANGAEA [数据集], https://doi.org/10.1594/PANGAEA.937781, 2021. #### 6. 冰芯：海冰密度 从MOSAiC主取芯站点采集的冰芯数据可从PANGAEA获取：MCS-FYI对应https://doi.org/10.1594/PANGAEA.956732，MCS-SYI对应https://doi.org/10.1594/PANGAEA.959830。 Oggier, M., Salganik, E., Whitmore, L., Fong, A. A., Hoppe, C. J. M., Rember, R., Høyland, K. V., Divine, D. V., Gradinger, R., Fons, S. W., Abrahamsson, K., Aguilar-Islas, A. M., Angelopoulos, M., Arndt, S., Balmonte, J. P., Bozzato, D., Bowman, J. S., Castellani, G., Chamberlain, E., Creamean, J., D'Angelo, A., Damm, E., Dumitrascu, A., Eggers, S. L., Gardner, J., Grosfeld, L., Haapala, J., Immerz, A., Kolabutin, N., Lange, B. A., Lei, R., Marsay, C. M., Maus, S., Müller, O., Olsen, L. M., Nuibom, A., Ren, J., Rinke, A., Sheikin, I., Shimanchuk, E., Snoeijs-Leijonmalm, P., Spahic, S., Stefels, J., Torres-Valdés, S., Torstensson, A., Ulfsbo, A., Verdugo, J., Vortkamp, M., Wang, L., Webster, M., Wischnewski, L., and Granskog, M. A.: First-year sea-ice salinity, temperature, density, oxygen and hydrogen isotope composition from the main coring site (MCS-FYI) during MOSAiC legs 1 to 4 in 2019/2020. PANGAEA [数据集], https://doi.org/10.1594/PANGAEA.956732, 2023. Oggier, M., Salganik, E., Whitmore, L., Fong, A. A., Hoppe, C. J. M., Rember, R., Høyland, K. V., Gradinger, R., Divine, D. V., Fons, S. W., Abrahamsson, K., Aguilar-Islas, A. M., Angelopoulos, M., Arndt, S., Balmonte, J. P., Bozzato, D., Bowman, J. S., Castellani, G., Chamberlain, E., Creamean, J., D'Angelo, A., Damm, E., Dumitrascu, A., Eggers, L., Gardner, J., Grosfeld, L., Haapala, J., Immerz, A., Kolabutin, N., Lange, B. A., Lei, R., Marsay, C. M., Maus, S., Olsen, L. M., Müller, O., Nuibom, A., Ren, J., Rinke, A., Sheikin, I., Shimanchuk, E., Snoeijs-Leijonmalm, P., Spahic, S., Stefels, J., Torres-Valdés, S., Torstensson, A., Ulfsbo, A., Verdugo, J., Vortkamp, M., Wang, L., Webster, M., Wischnewski, L., and Granskog, M. A.: Second-year sea-ice salinity, temperature, density, oxygen and hydrogen isotope composition from the main coring site (MCS-SYI) during MOSAiC legs 1 to 4 in 2019/2020. PANGAEA [数据集], https://doi.org/10.1594/PANGAEA.959830, 2023.