Alfred Wegener Institute for Polar and Marine Research
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ESA Climate Change Initiative (CCI) Permafrost – AWI WebGIS visualisation of Permafrost Essential Climate Variable (ECV) time series
Get PDFGIS server and desktop GIS technology support scientific work at all levels, from data collections and
processing to data management and data visualisation. Here we present how the development and
publication of a scalable WebGIS supports the ESA DUE Globpermafrost (2016-2018) and the follow-on
ESA CCI+ Permafrost I (2018-2021) and II (2022-2025).
Within GlobPermafrost a wide range of experimental remote sensing products were processed: Landsat
multispectral index trends, Arctic land cover, lake ice grounding, surface deformation, and rock glacier
velocities. According to the ECVs required by the Global Climate Observing System (GCOS) the main
products were global permafrost temperature, Active Layer Thickness and permafrost probability maps
produced by a TTOP model forced by satellite derived surface temperature and snow. CCI+ Permafrost
continued with enhanced modelling based on the community CryoGrid permafrost model producing mean
annual ground temperature MAGT per depth down to 10 m, Active Layer Thickness (ALT), and Permafrost
Probability and Extent (PEX) per pixel.
To make resulting data products accessible via visualisation, several WebGIS projects e.g. ‘Arctic’ WebGIS
visualising circum-artic products, as well as small-scale regional WebGIS projects like ‘Alps’, ‘Andes’ or
‘Central Asia’ that visualise e. g. higher spatial resolution products like rock glacier movements have been
made publicly available using WebGIS technology within maps@awi (http://maps.awi.de), a highly scalable
data visualisation unit within AWI’s data workflow framework O2A (from Observation to Archive). GIS
services have been created and designed using ArcGIS Pro and finally published as Web Map Services
(WMS), an internationally standardized format (Open Geospatial Consortium (OGC)), using ArcGIS Server.
The project-specific data WMS as well as a resolution-specific background map WMS are embedded into a
GIS viewer application based on Leaflet, an open-source JavaScript library.
The CCI+ Permafrost Time Series WebGIS provides circumpolar MAGT, PEX, and ALT for 1997-2021 as a
time slider visualization in annual resolution. Beside remote sensing and model-derived data products, the
locations of the GCOS ground-monitoring networks of the permafrost community, the Global Terrestrial
Network for Permafrost (GTN-P) managed by the International Permafrost Association (IPA) were add as
feature layer. ESA CCI+ data products are DOI-registered and archived in the ESA CEDA data archive
From practitioners’ knowledge to climate modelling and back: – Using climate model projections to provide relevant climate information to Arctic reindeer herding communities
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The Solar System's Passage through the Radcliffe Wave during the Middle Miocene
Get PDFAs the Earth and the other planets orbit around the Sun, the Solar System itself revolves around the center of the Milky Way, our Galaxy. The Milky Was is far from being a static and homogeneous environment. On large scales, the stars, the gas, and the dust are organized into a rotating spiral structure that extend from the center into the galactic disk. On smaller scales, the environment between the stars, also known as the interstellar medium (ISM), is continuously shaped by different&#160; events and mechanism, like supernovae explosions, stellar winds, Galactic shear, magnetic fields, etc.&#160;The Solar System, located at about 27&#8217;000 light-years from the center of the Milky Way, completes a full orbit around the Galactic center in about 225 million years (Myr). The constantly evolving environment, combined with the Sun&#8217;s peculiar velocity relative to the average velocity of the surrounding gas and stars, causes the Solar System to &#8220;sail&#8221; various Galactic environments with different gas densities.&#160;Encounters with dense gas regions, such as gas clouds or supernova shock fronts, can compress the heliosphere, exposing parts of the Solar System to the ISM. These encounters also increase the influx of interstellar dust into the Solar System and Earth's atmosphere. A greater influx of dust would result into the decrease of the amount of sunlight reaching Earth and, by bringing radioactive elements from the supernovae, might also cause radionuclides anomalies in geological records.Recently, by the means of new astronomical data provided by the Gaia mission, the 3D structure of the environment surrounding the Sun has been unveiled. This has led to the identification of previously unknown Galactic structures, such as the Radcliffe Wave. This raises the question of whether the Sun has encountered any of these structures.In our work, we study the passage of the Solar System through the Radcliffe Wave gas structure over the past 30 Myr. We find that the Solar System&#8217;s trajectory intersected the Radcliffe Wave in the Orion star forming region. We have constrained the timing of this event to between 18.2 and 11.5 Myr ago, with the closest approach occurring between 14.8 and 12.4 Myr ago.&#160;Notably, this period is synchronous with the Middle Miocene Climate Transition on Earth, providing an interdisciplinary link with paleoclimatology. We also estimate the potential impact of the crossing of the Radcliffe Wave on climate on Earth and suggest possible future developments for this work. As&#160;the crossing could also lead to anomalies in radionuclide abundances, we highlight its importance for the field of geology and nuclear astrophysics.</jats:p
The Role of Ballasting, Seawater Viscosity and Oxygen‐Dependent Remineralization for Export and Transfer Efficiencies in the Global Ocean
No full textAbstractThe particulate organic carbon (POC) flux from the euphotic zone to the deep ocean is central to the biological carbon pump. It is typically evaluated using “export efficiency” and “transfer efficiency,” which reflect POC formation and sinking and carbon sequestration efficiency in the ocean's interior, respectively. Since observations of these metrics are limited, biogeochemical models can elucidate the controls of large‐scale patterns. This study uses the global ocean‐biogeochemical model FESOM‐REcoM, with a new sinking routine that accounts for ballast minerals, seawater viscosity, and oxygen‐dependent remineralization in POC sinking and remineralization, to identify the drivers of global export and transfer efficiency. We find that export efficiency is highest at high latitudes, where diatoms, mesozooplankton, and macrozooplankton dominate the plankton community, but that high export efficiency does not always imply high transfer efficiency. Omitting ballast minerals decreases export efficiency by 20% in the Southern Ocean, yet the globally integrated POC flux out of the euphotic zone (5.4–5.6 Pg C ) and the global average export efficiency (14.7%–15.4%) are relatively insensitive to seawater viscosity, mineral ballasting, or oxygen‐dependent remineralization. In contrast, global transfer efficiency is more sensitive to these processes and varies between 21% and 25% in the simulations, with the largest reduction by 23% observed when omitting ballasting in subtropical, low‐productivity regions. Our findings suggest that assumptions about ballasting and background sinking speed could explain previous discrepancies in the literature regarding the highest transfer efficiencies in low or high latitudes. Notably, while plankton community structure determines export efficiency regimes, zooplankton fecal pellets drive high transfer efficiencies in regions with high export efficiency, like the Southern Ocean.</jats:p
Adaptation of global primary production model to the Greenland Sea conditions: parameterization and monitoring for 1998-2022
Get PDFPhytoplankton are responsible for releasing half of the world’s oxygen and for removing large amounts of carbon dioxide from surface waters. Despite many studies on the topic conducted in the past decades, we are still far from a good understanding of ongoing rapid changes in the Arctic Ocean and how they will affect phytoplankton and the whole ecosystem. An example is the difference in net primary production modelling estimates, which differ twice globally and fifty times when only the Arctic region is considered. Here, we aim to improve the quality of Greenland Sea primary production estimates, by testing different versions of primary production model against in situ data and then calculating regional estimates and trends for 1998-2022 for those performing best. As a baseline, we chose the commonly used global primary production model and tested it with different combinations of empirical relationships and input data. Local empirical relationships were taken from measurements by the literature and derived from the unpublished data of Institute of Oceanology of Polish Academy of Sciences across the Fram Strait. For validation, we took historical net primary production 14C data from literature and added to it our own gross primary production O2 measurements. Field data showed good agreement between primary production measured with 14C and O2 evolution methods. From all the model setups, those including local chlorophyll a profile and local absorption spectrum best reproduced in situ data. Our modelled regional annual primary production estimates are equal to 346 TgC/year for the Nordic Seas region and 342 TgC/year for the Greenland Sea sector of the Arctic defined as 45°W-15°E, 66°33′N-90°N. These values are higher than those previously reported. Monthly values show a seasonal cycle with less monthly variability than previously reported. No significant increase or decrease in primary production was observed when studying regionally averaged trends. The accuracy of the selected here model setups to reproduce the field data in terms of Root Mean Square Difference is better than in the related Arctic studies. The improved primary production estimates strengthen researchers’ ability to assess carbon flux and understand biogeochemical processes in the Greenland Sea
Lack of evidence for alternative stable states in Northern Hemisphere forests during the past 8 ka
Get PDFAbstract
With increased pressure from anthropogenic climate change, boreal forests are suspected to be approaching tipping points which could cause large-scale changes in tree cover and affect global climatic feedback. However, evidence for this proposed tipping is sparse and relies heavily on observations on short time scales from remote sensing data and space-for-time substitutions. Here we make use of an extensive pollen data set including 239 records of large lakes to investigate the existence of alternative stable forest cover states in the boreal forest and its adjacent biomes during the last 8000 years. By using a multimodality measure on time series of reconstructed tree cover we find very little multimodality in pollen data. To test whether this lack of multimodality is caused by limitations in the paleo data set we perform surrogate experiments. Surrogate data with alternative stable states based on the paleo vegetation–climate relationship were generated and significant multimodality was found more often than for the pollen-based tree cover (24.7% and 5.3% respectively). The response of tree cover to climate may, therefore, be more gradual and not as abrupt as would be expected from remote sensing analyses on stability. The apparent alternative stability hypothesized in the analyses of climate–vegetation relationships could be due to the strong spatial heterogeneity of environmental factors and vegetation responses as an artifact of space-for-time substitutions. Even though current and upcoming shifts in the boreal forest are indisputable and a reason for strong concern, these changes could happen gradually without going through large-scale tipping between alternative stable states. To aid adaptation and conservation measures, more knowledge is needed about boreal forest drivers and their spatial heterogeneity.</jats:p
Potential plant extinctions with the loss of the Pleistocene mammoth steppe
Get PDFDuring the Pleistocene-Holocene transition, the dominant mammoth steppe ecosystem across northern Eurasia vanished, in parallel with megafauna extinctions. However, plant extinction patterns are rarely detected due to lack of identifiable fossil records. Here, we introduce a method for detection of plant taxa loss at regional (extirpation) to potentially global scale (extinction) and their causes, as determined from ancient plant DNA metabarcoding in sediment cores (sedaDNA) from lakes in Siberia and Alaska over the past 28,000 years. Overall, potential plant extinctions track changes in temperature, in vegetation, and in megafauna extinctions at the Pleistocene-Holocene transition. Estimated potential plant extinction rates were 1.7-5.9 extinctions per million species years (E/MSY), above background extinction rates but below modern estimates. Major potential plant extinction events were detected around 17,000 and 9000 years ago which lag maximum vegetation turnover. Our results indicate that herbaceous taxa and taxa contributing less to beta diversity are more vulnerable to extinction. While the robustness of the estimates will increase as DNA reference libraries and ancient sedaDNA data expand, the available data support that plants are more resilient to environmental changes than mammals
Radiocarbon measurements of dissolved inorganic carbon (DIC) in sediment porewater and seawater at AWI MICADAS
Get PDFRadiocarbon (14C) measurements on dissolved inorganic carbon (DIC) are a powerful tool to trace water masses and
carbon cycling in the ocean. Existing methodologies to determine the 14C content of seawater DIC requires large
volumes of sample (usually >100 mL) and specialized graphitization techniques to achieve the accuracy and
precision needed for meaningful data interpretation. The advancement of the CO2 gas ionization accelerator mass
spectrometry (AMS) technique today allows routine 14C measurements on small samples (<100 μgC) and may thus
permit reducing the sample volumes needed to determine 14C content of seawater DIC to ∼2 mL. The proposed
method utilizes the carbonate handling system (CHS), gas interface system (GIS) and MICADAS AMS, and
provides good accuracy but reduced precision compared to established methods. Good accuracy is shown by
comparing results for a marine in-house DIC standard and a DIC seawater profile from Antarctica between the
proposed CHS-GIS-MICADAS approach and reference measurements conducted on the same material at
established laboratories (ETH and NOSAMS). Further, two sedimentary porewater profiles from a fjord system in
Svalbard are presented. Despite good agreement, the precision of the CHS-GIS-MICADAS approach is reduced,
potentially limiting possible interpretations on seawater DIC. Nonetheless, the reduction of sample volumes proves
particularly helpful to analyze porewater DIC from sediment cores, where sample material is notoriously limited, reduces the required amounts of toxic HgCl2 and simplifies expedition logistics