ICDC Veröffentlichungen

@article{8d2501c67a1c41fbb4c24467e4268088,

title = "Exploring sea ice transport dynamics at the eastern gate of the Ross Sea",

abstract = "As Antarctic sea ice extent continues to reach record lows, significant efforts have been directed towards understanding the underlying processes and their regional differences within the Southern Ocean. Here, we explore the dynamics of zonal sea ice transport at the eastern gate of the Ross Sea from 1988 to 2023 using GIOMAS-model and ERA5-reanalysis data. Our analysis reveals a modest overall increase in eastward sea ice transport (3.721 ± 0.672 km³/month per decade), with diverging trends in the coastal and open ocean zones. Driven by easterly winds and the Antarctic Slope Current, the predominant westward transport in the coastal region experienced a significant rise during the early 2000s, followed by a steep decline post-2011. Conversely, driven by the Antarctic Circumpolar Current, the strong open-ocean transport exhibited a moderate increase towards the Amundsen Sea until the late 1990s, which was interrupted by a reversal in 2007. The variability of zonal sea ice transport and its underlying conditions (sea ice concentration, thickness, and zonal drift) revealed considerable shifts throughout the different decades and on seasonal scales. During austral winter, approximately half of the zonal sea ice transport variability seems to be driven by large-scale teleconnections, including the Southern Annular Mode, Southern Oscillation Index, Amundsen Sea Low and the Zonal Wave 3 with considerable impacts on the wind stress field. Whereas during summer, the Southern Oscillation Index emerges as the dominant driver, exhibiting a significant positive correlation (r=0.55, p<0.001) that reflects the influence of the El Ni{\~n}o-Southern Oscillation, while other teleconnections play minimal roles. Our study highlights the complex nature of sea ice transport through the eastern gate of the Ross Sea towards the Amundsen Seas, where contrasting climatic conditions are known to occur.",

author = "Naomi Krauzig and Daniela Flocco and Stefan Kern and Enrico Zambianchi",

year = "2024",

month = dec,

doi = "10.1016/j.dsr2.2024.105428",

language = "English",

volume = "218",

journal = "Deep Sea Research Part II: Topical Studies in Oceanography",

issn = "0967-0645",

publisher = "Elsevier Ltd",

@article{225c3c97c5c745bd823840e77c0508c7,

title = "Evaluation of Microwave Radiometer Sea Ice Concentration Products over the Baltic Sea",

abstract = "Sea ice concentration (SIC) monitoring in the Arctic using microwave radiometer data is a well-established method with numerous published accuracy studies. For the Baltic Sea, accuracy studies have not yet been conducted. In this study, we evaluated five different SIC products over the Baltic Sea using MODIS (250 m) and Sentinel-2 (10 m) open water–sea ice classification charts. The selected SIC products represented different SIC algorithm types, e.g., climate data records and near-real-time products. The one-to-one linear agreement between the radiometer SIC dataset and the MODIS/Sentinel-2 SIC was always quite poor; the slope of the linear regression was from 0.40 to 0.77 and the coefficient of determination was from 0.26 to 0.80. The standard deviation of the difference was large and varied from 15.5% to 26.8%. A common feature was the typical underestimation of the MODIS/Sentinel-2 SIC at large SIC values (SIC > 60%) and overestimation at small SIC values (SIC < 40%). None of the SIC products performed well over the Baltic Sea ice, and they should be used with care in Baltic Sea ice monitoring and studies.",

author = "Marko M{\"a}kynen and Stefan Kern and Rasmus Tonboe",

year = "2024",

month = nov,

day = "27",

doi = "10.3390/rs16234430",

language = "English",

volume = "16",

journal = "Remote Sensing",

issn = "2072-4292",

publisher = "Molecular Diversity Preservation International (MDPI)",

number = "23",

@article{77a11899c0dc4574b2a9308867ed1ee6,

title = "Estimating the uncertainty of sea-ice area and sea-ice extent from satellite retrievals",

abstract = "The net Arctic sea-ice area (SIA) can be estimated from the sea-ice concentration (SIC) by passive microwave measurements from satellites. To be a truly useful metric, for example of the sensitivity of the Arctic sea-ice cover to global warming, we need, however, reliable estimates of its uncertainty. Here we retrieve this uncertainty by taking into account the spatial and temporal error correlations of the underlying local sea-ice concentration products. As 1 example year, we find that in 2015 the average observational uncertainties of the SIA are 306 000 km2 for daily estimates, 275 000 km2 for weekly estimates, and 164 000 km2 for monthly estimates. The sea-ice extent (SIE) uncertainty for that year is slightly smaller, with 296 000 km2 for daily estimates, 261 000 km2 for weekly estimates, and 156 000 km2 for monthly estimates. These daily uncertainties correspond to about 7 % of the 2015 sea-ice minimum and are about half of the spread in estimated SIA and SIE from different passive microwave SIC products. This shows that random SIC errors play a role in SIA uncertainties comparable to inter-SIC-product biases. We further show that the September SIA, which is traditionally the month with the least amount of Arctic sea ice, declined by 105000±9000 km2 a-1 for the period from 2002 to 2017. This is the first estimate of a SIA trend with an explicit representation of temporal error correlations.",

author = "Andreas Wernecke and Dirk Notz and Stefan Kern and Thomas Lavergne",

note = "Publisher Copyright: Copyright {\textcopyright} 2024 Andreas Wernecke et al.",

year = "2024",

month = may,

day = "17",

doi = "10.5194/tc-18-2473-2024",

language = "English",

volume = "18",

pages = "2473--2486",

journal = "Cryosphere",

issn = "1994-0416",

publisher = "Copernicus Publications",

number = "5",

@article{75501cfb84cd45e9a3afe93cb1d86bc3,

title = "Navigability of the Northern Sea Route for Arc7 ice-class vessels during winter and spring sea-ice conditions",

abstract = "Sea ice hinders the navigability of the Arctic, especially in winter and spring. However, three Arc7 ice-class Liquefied Natural Gas carrying vessels safely transited the Northern Sea Route (NSR) without icebreaker assistance in January 2021. More and more Arc7 ice-class vessels are putting into the transit services in the NSR. Therefore, it is necessary to analyze sea-ice conditions and their impact on navigation during wintertime, and the future navigability of Arc7 ice-class vessels along the NSR during winter and spring. Based on sea ice datasets from satellite observations and a model using data assimilation, we explored the sea-ice conditions and their impact during the first three successful commercial voyages through the NSR in winter. In addition, we analyzed the sea ice variation and estimated navigability for Arc7 ice-class vessels in the NSR from January to June of the years 2021–2050 using future projections of the sea-ice cover by the Coupled Model Inter-comparison Project Phase 6 (CMIP6) models under two emission scenarios (SSP2-4.5 and SSP5-8.5). The results reveal lower sea ice thickness and similar sea ice concentration during these three transits relative to the past 42 years (from 1979 to 2020). We found the thickness has a larger impact on the vessels{\textquoteright} speeds than sea ice concentration. Very likely sea ice thickness played a larger role than the sea ice concentration for the successful transit of the NSR in winter 2021. Future projections suggest sea ice thickness will decrease further in most regions of the NSR from January to June under all scenarios enabling increased navigability of the NSR for Arc7 ice-class vessels. Such vessels could transit through the NSR from January to June under all scenarios by 2050, while some areas near the coast of East Siberian Sea remain inaccessible for Arc7 ice-class vessels in spring (April and May). These findings can support the strategic planning of shipping along the NSR in winter and spring.",

keywords = "Northern sea route, Arc7 ice-class vessel, sea ice thickness, sea ice concentration, Navigability, Arctic",

author = "Chen Shi-Yi and Stefan Kern and Li Xin-Qing and Hui Feng-Ming and Ye Yu-Fang and Xiao Cheng",

year = "2022",

month = sep,

day = "16",

doi = "10.1016/j.accre.2022.09.005",

language = "English",

volume = "2022",

journal = "Advances in Climate Change Research",

issn = "1674-9278",

publisher = "KeAi Communications Co.",

@article{d8c24eb882254f8a8bb5fe0891ea95b5,

title = "A New Structure for the Sea Ice Essential Climate Variables of the Global Climate Observing System",

abstract = "Climate observations inform about the past and present state of the climate system. They underpin climate science, feed into policies for adaptation and mitigation, and increase awareness of the impacts of climate change. The Global Climate Observing System (GCOS), a body of the World Meteorological Organization (WMO) assesses the maturity of the required observing system and gives guidance for its development. The Essential Climate Variables (ECVs) are central to GCOS and the global community must monitor them with the highest standards in the form of Climate Data Records (CDR). Today, a single ECV - the sea ice ECV - encapsulates all aspects of the sea-ice environment. In the early 1990s it was a single variable (sea-ice concentration) but is today an umbrella for four variables (adding thickness, edge/extent, and drift). In this contribution, we argue that GCOS should from now on consider a set of seven ECVs (sea-ice concentration, thickness, snow-depth, surface temperature, surface albedo, age, and drift). These seven ECVs are critical and cost-effective to monitor with existing satellite Earth Observation capability. We advise against placing these new variables under the umbrella of the single sea ice ECV. To start a set of distinct ECVs is indeed critical to avoid adding to the sub-optimal situation we experience today, and to reconcile the sea ice variables with the practice in other ECV domains. This work was presented at the 29th GCOS Steering Committee meeting in December 2021.",

author = "Thomas Lavergne and Stefan Kern and Signe Aaboe and Lauren Derby and Gorm Dybkjaer and Gilles Garric and Petra Heil and Stefan Hendricks and J{\"u}rgen Holfort and Stephen Howell and Jeffrey Key and Jan Lieser and Ted Maksym and Wieslaw Maslowski and Walt Meier and Joaquin Munoz-Sabater and Julien Nicolas and Burcu {\"O}zsoy and Benjamin Rabe and Wolfgang Rack and Marilyn Raphael and {de Rosnay}, Patricia and Vasily Smolianitsky and Steffen Tietsche and Jinro Ukita and Marcello Vichi and Penelope Wagner and Sascha Willmes and Xi Zhao",

year = "2022",

month = mar,

day = "16",

doi = "10.1175/BAMS-D-21-0227.1",

language = "English",

volume = "2022",

journal = "Bulletin of the American Meteorological Society",

issn = "0003-0007",

publisher = "American Meteorological Society",

@article{8f003a820a9944179d88dd419d3be36a,

title = "Simulated Geophysical Noise in Sea Ice Concentration Estimates of Open Water and Snow-Covered Sea Ice",

author = "Tonboe, {Rasmus Tage} and Vishnu Nandan and Marko Makynen and Pedersen, {Leif Toudal} and Stefan Kern and Thomas Lavergne and Johanne Oelund and Gorm Dybkjaer and Roberto Saldo and Marcus Huntemann",

year = "2022",

month = feb,

day = "3",

doi = "10.1109/JSTARS.2021.3134021",

language = "English",

volume = "15",

pages = "1309--1326",

journal = "IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing (J-STARS)",

issn = "1939-1404",

publisher = "Institute of Electrical and Electronics Engineers Inc.",

@article{19690a5e38cc4336886042fa93844f76,

title = "Satellite passive microwave sea-ice concentration data set intercomparison using Landsat data",

abstract = "We report on results of an intercomparison of 10 global sea-ice concentration (SIC) data products at 12.5 to 50.0ĝ€¯km grid resolution from satellite passive microwave (PMW) observations. For this we use SIC estimated from >350 images acquired in the visible-near-infrared frequency range by the joint National Aeronautics and Space Administration (NASA) and United States Geological Survey (USGS) Landsat sensor during the years 2003-2011 and 2013-2015. Conditions covered are late winter/early spring in the Northern Hemisphere and from late winter through fall freeze-up in the Southern Hemisphere. Among the products investigated are the four products of the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Ocean and Sea Ice Satellite Application Facility (OSI SAF) and European Space Agency (ESA) Climate Change Initiative (CCI) algorithms SICCI-2 and OSI-450. We stress the importance to consider intercomparison results across the entire SIC range instead of focusing on overall mean differences and to take into account known biases in PMW SIC products, e.g., for thin ice. We find superior linear agreement between PMW SIC and Landsat SIC for the 25 and the 50ĝ€¯km SICCI-2 products in both hemispheres. We discuss quantitatively various uncertainty sources of the evaluation carried out. First, depending on the number of mixed ocean-ice Landsat pixels classified erroneously as ice only, our Landsat SIC is found to be biased high. This applies to some of our Southern Hemisphere data, promotes an overly large fraction of Landsat SIC underestimation by PMW SIC products, and renders PMW SIC products overestimating Landsat SIC particularly problematic. Secondly, our main results are based on SIC data truncated to the range 0ĝ€¯% to 100ĝ€¯%. We demonstrate using non-Truncated SIC values, where possible, can considerably improve linear agreement between PMW and Landsat SIC. Thirdly, we investigate the impact of filters often used to clean up the final products from spurious SIC over open water due to weather effects and along coastlines due to land spillover. Benefiting from the possibility to switch on or off certain filters in the SICCI-2 and OSI-450 products, we quantify the impact land spillover filtering can have on evaluation results as shown in this paper.",

author = "Stefan Kern and Thomas Lavergne and Pedersen, {Leif Toudal} and Tonboe, {Rasmus Tage} and Louisa Bell and Maybritt Meyer and Luise Zeigermann",

year = "2022",

month = jan,

day = "26",

doi = "10.5194/tc-16-349-2022",

language = "English",

volume = "16",

pages = "349--378",

journal = "The Cryosphere",

issn = "1994-0416",

publisher = "Copernicus Publications",

number = "1",