Heidrun Matthes - Academia.edu (original) (raw)

Papers by Heidrun Matthes

EPIC3, 2011

For several years, the Arctic has now been in the focus of scientific debate on climate change. I... more For several years, the Arctic has now been in the focus of scientific debate on climate change. It is a region of high spatio-temporal climate variability and additionally a region of high climate sensitivity due to strong feedback processes like the ice-albedo feedback. As there is a strong linkage to the global climate system, changes in the Arctic impact onto the global climate. In modeling the Arctic climate, regional climate models are an important tool because with their high resolution they provide the possibility to account for the horizontally heterogeneous soil and surface characteristics. Here, the regional climate model HIRHAM is used with 25km resolution for the analysis of spatial patterns, variability and trends of the Arctic climate and temperature-derived indices describing climate extremes. Inter-annual temperature variability (ITV) for present-day conditions (1958 to 2008) is examined from station data, the ERA40 re-analysis and HIRHAM results. It shows a pronounced decadal variability and specific regional and seasonal characteristics. Seasonal temperatures in general show warming trends, though they are mostly not statistically significant. Intra-seasonal extreme temperature range (ETR) trends were of mixed sign and only significant from station data over the eastern Russian Arctic. In general, the spatial pattern and magnitude of the Arctic temperature variability, both of seasonal temperature and intra-seasonal ETR, are well reproduced by HIRHAM. The large variability of the Arctic temperature, which is inherent in the analysis period, demonstrates that natural variability is an important factor in the Arctic climate. This variability is not restricted to climate means but also appears in temperature extremes. An analysis of station-derived an re-analysis-based climate indices shows complex behavior, some measures like frost days show consistent decrease (i.e. warming), while others like cold spell days provide a more diverse picture. As with seasonal temperatures, only few trends are found statistically significant. The indices examined exhibit strong inter-annual and decadal-scale variability and heterogeneous spatial patterns. These climate indices are then employed in the validation of the HIRHAM model. The model well reproduces trends and variability of most indices while there is an offset in some absolute values (e.g. frost days, growing degree days). Other measures like cold and warm spells are calculated with non-systematic biases; deviations in trends and variability occur in summer for cold spells and in spring and summer for warm spells due to an earlier spring warming and a too low variability of the maximum temperature over sea ice in HIRHAM. HIRHAM is furthermore used as a downscaling tool for future projections (ECHAM5/MPIOM output under the IPCC scenario SRES A1B). The strong increase in mean annual air temperature (5–8 K) is expected to increase active layer thickness and permafrost boundaries will move northwards. On top of this general warming trend, the additional analysis of future changes, using the mean conditions for the warmer climate, highlights some particularly vulnerable regions (West Siberian Plain, Laptev Sea coast, Canadian Archipelago), which are projected to be warmer, to experience increased warm spells and to be wetter in summer; all this contributes to amplify the permafrost degradation initiated by the general warming. Different realizations of HIRHAM are run for a sensitivity study looking into the importance of land-surface-conditions for climate model projections. The different model setups are: (1) the incorporation of freezing/thawing of soil moisture, (2) the inclusion of top organic soil horizons typical for the Arctic and (3) a vegetation shift due to a changing climate. Direct thermal responses in 2m air temperature and turbulent heat fluxes over land lead to changes in mean sea level pressure and geopotential height throughout the Arctic. This points to the importance of dynamical feedbacks within the atmosphere-land system. Land and soil processes have a distinct remote influence on large scale circulation patterns in addition to their direct, regional effects. The projected changes are clearly afflicted with uncertainties due to the different setups for land-surface-conditions; the highest temperature uncertainties are found over tundra regions. This demonstrates that for an improvement of the land-surface scheme of the HIRHAM model, all three representations of land-surface-processes have to be incorporated.

The Open Atmospheric Science Journal, Jun 3, 2010

This paper discusses results of a simulation with the regional climate model HIRHAM for 1958-2001... more This paper discusses results of a simulation with the regional climate model HIRHAM for 1958-2001, driven by the ECMWF reanalysis (ERA40) data over the Arctic domain. The aim is to analyze the ability of the model to capture certain features of climate extremes derived from daily mean, maximum and minimum temperatures. For this purpose, a range of climate indices (frost days, cold and warm spell days, growing degree days and growing season length) was calculated from the model output as well as from ERA40 data and region-specific station data for Eastern and Western Russian Arctic for comparison. It is demonstrated that the model captures the main features in the spatial distribution and temporal development of most indices well. Though systematic deviations in the seasonal means occur in various indices (frost days, growing degree days), variability and trends are well reproduced. Seasonal mean patterns in frost days are reproduced best, though the model persistently calculates too many frost days. Seasonal means of cold and warm spell days are reproduced without systematic biases, though deviations occur in summer for cold spells and in spring and summer for warm spells due to an early spring warming in the regional climate model and a low variability of the daily maximum temperature over sea ice.

Journal Of Geophysical Research: Atmospheres, Dec 29, 2020

Clouds in the Arctic have a multifaceted role within the Arctic climate system. Solid precipitati... more Clouds in the Arctic have a multifaceted role within the Arctic climate system. Solid precipitation on sea ice acts as a thermal modulator by changing the surface albedo, the thermal conductivity, and the roughness length for momentum at the top of the sea ice, whereas precipitation into open water provides freshwater input to the ocean (Vihma et al., 2016). Regarding radiation from clouds in the Arctic, the surface energy budget (SEB) is constrained seasonally by cloud properties (Intrieri et al., 2002; Shupe & Intrieri, 2004), while Arctic clouds are influenced by components of the SEB, in particular the sensible heat flux (SHF), latent heat flux (LHF), and horizontal heat and moisture transports. Although appropriate representation of Arctic clouds in numerical models has remained a challenge over the previous three decades (e.g., Curry et al., 1996), several issues regarding their representation have been revealed through use of new satellite products and general circulation models. For example, these issues concern underestimation of the cloudtop albedo, which causes positive downward shortwave radiation (SWD) model biases (English et al., 2014), negative cloud liquid water model biases and surface albedo adjustment to achieve a credible Arctic sea ice mean thickness (Kay et al., 2016), and significant intermodel differences in low-level cloud amount associated with lower tropospheric stability and cloud microphysical schemes (Taylor et al., 2019).

Environmental Research Letters, Jun 1, 2021

Arctic cyclones, as a prevalent feature in the coupled dynamics of the Arctic climate system, hav... more Arctic cyclones, as a prevalent feature in the coupled dynamics of the Arctic climate system, have large impacts on the atmospheric transport of heat and moisture and deformation and drifting of sea ice. Previous studies based on historical and future simulations with climate models suggest that Arctic cyclogenesis is affected by the Arctic amplification of global warming, for instance, a growing land-sea thermal contrast. We thus hypothesize that biogeophysical feedbacks (BF) over the land, here mainly referring to the albedo-induced warming in spring and evaporative cooling in summer, may have the potential to significantly change cyclone activity in the Arctic. Based on a regional Earth system model (RCA-GUESS) which couples a dynamic vegetation model and a regional atmospheric model and an algorithm of cyclone detection and tracking, this study assesses for the first time the impacts of BF on the characteristics of Arctic cyclones under three IPCC Representative Concentration Pathways scenarios (i.e. RCP2.6, RCP4.5 and RCP8.5). Our analysis focuses on the spring-and summer time periods, since previous studies showed BF are the most pronounced in these seasons. We find that BF induced by changes in surface heat fluxes lead to changes in land-sea thermal contrast and atmospheric stability. This, in turn, noticeably changes the atmospheric baroclinicity and, thus, leads to a change of cyclone activity in the Arctic, in particular to the increase of cyclone frequency over the Arctic Ocean in spring. This study highlights the importance of accounting for BF in the prediction of Arctic cyclones and the role of circulation in the Arctic regional Earth system.

Atmospheric Research, Mar 1, 2019

Air temperature at 2-m (T2) in the Arctic represents its local climate. Its quantification is one... more Air temperature at 2-m (T2) in the Arctic represents its local climate. Its quantification is one of the major criteria to evaluate the performance of numerical models in reflecting the complex physical and dynamical processes associated with the surface energy balance. This study uses HIRHAM5 regional climate model to simulate the Arctic climate during 1979-2014. Evaluations with Arctic station observations reveal that HIRHAM5 can generally reproduce the temporal and spatial variation of the T2, although a systematic cold bias of ca. −2°C exists in all seasons. The overestimated surface albedo in spring and autumn, and the underestimated downward solar radiation associated with the cloud cover in summer are the main causes of the cold biases in each respective season. The model also simulates the Arctic warming well (with linear trends of 0.40°C decade −1 for the annual mean T2), although the magnitude is less than that from ERA-Interim (0.55°C decade −1) and station observations (0.60°C decade −1). In addition, strong decadal variability is clear in the T2 trends calculated using an 11-year moving windows, especially in winter and spring, which is mainly associated with the variability of the Arctic/North Atlantic Oscillations.

Eiszeitalter und Gegenwart, May 25, 2020

The late Pleistocene Yedoma Ice Complex is an ice-rich and organic-bearing type of permafrost dep... more The late Pleistocene Yedoma Ice Complex is an ice-rich and organic-bearing type of permafrost deposit widely distributed across Beringia and is assumed to be especially prone to deep degradation with warming temperature, which is a potential tipping point of the climate system. To better understand Yedoma formation, its local characteristics, and its regional sedimentological composition, we compiled the grain-size distributions (GSDs) of 771 samples from 23 Yedoma locations across the Arctic; samples from sites located close together were pooled to form 17 study sites. In addition, we studied 160 samples from three non-Yedoma ice-wedge polygon and floodplain sites for the comparison of Yedoma samples with Holocene depositional environments. The multimodal GSDs indicate that a variety of sediment production, transport, and depositional processes were involved in Yedoma formation. To disentangle these processes, a robust endmember modeling analysis (rEMMA) was performed. Nine robust grain-size endmembers (rEMs) characterize Yedoma deposits across Beringia. The study sites of Yedoma deposits were finally classified using cluster analysis. The resulting four clusters consisted of two to five sites that are distributed randomly across northeastern Siberia and Alaska, suggesting that the differences are associated with rather local conditions. In contrast to prior studies suggesting a largely aeolian contribution to Yedoma sedimentation, the wide range of rEMs indicates that aeolian sedimentation processes cannot explain the entire variability found in GSDs of Yedoma deposits. Instead, Yedoma sedimentation is controlled by local conditions such as source rocks and weathering processes, nearby paleotopography, and diverse sediment transport processes. Our findings support the hypothesis of a polygenetic Yedoma origin involving alluvial, fluvial, and niveo-aeolian transport; accumulation in ponding waters; and in situ frost weathering as well as postdepositional processes of solifluction, cryoturbation, and pedogenesis. The characteristic rEM composition of the Yedoma clusters will help to improve how grain-size-dependent parameters in per-Published by Copernicus Publications on behalf of the Deutsche Quartärvereinigung (DEUQUA) e.V. L. Schirrmeister et al.: The genesis of Yedoma Ice Complex permafrost mafrost models and soil carbon budgets are considered. Our results show the characteristic properties of ice-rich Yedoma deposits in the terrestrial Arctic. Characterizing and quantifying site-specific past depositional processes is crucial for elucidating and understanding the trajectories of this unique kind of ice-rich permafrost in a warmer future. Kurzfassung: Der spätpleistozäne Yedoma Eiskomplex ist ein eisreicher und organikhaltiger Permafrosttyp, der in Beringia weit verbreitet ist. Durch den hohen Eisanteil wird der Yedoma Eiskomplex im Zuge des Klimawandels als besonders anfällig für tiefgreifende Störungen betrachtet und damit ein potentieller Kipppunkt des Klimasystems. Um seine Entstehung, die lokalen Eigenschaften und die regionale sedimentologische Zusammensetzung besser zu verstehen, haben wir die Korngrößenverteilung von 771 Proben an 23 Yedoma-Standorten in der Arktis zusammengestellt; räumlich eng zusammenhängende Probenserien wurden zu 17 Untersuchungsstandorten zusammengefasst. Darüber hinaus wurden 160 Proben aus nicht Yedoma-Ablagerungen von drei Eiskeilpolygon-und Überschwemmungsgebieten als holozäne Referenzen untersucht. Die multimodalen Korngrößenverteilungen zeigen, dass eine Vielzahl von Sedimentbildungs-, Transport-und Ablagerungsprozessen an der Yedoma-Entstehung beteiligt waren. Um diese Prozesse zu erkennen, wurde eine robuste Endmembermodellierungsanalyse (rEMMA) durchgeführt. Neun robuste Endmember (rEM) charakterisieren die Yedoma-Ablagerungen über ganz Beringia. Die untersuchten Standorte der Yedoma-Ablagerungen wurden anschließend mittels Clusteranalyse klassifiziert. Die daraus resultierenden vier Cluster umfassen zwei bis fünf Untersuchungsstandorte, die unregelmäßig über den Nordosten Sibiriens und Alaska verteilt sind. Die breite Palette von rEMs zeigt, dass nicht allein äolische Sedimentationsprozesse für die Variabilität in den Korngrößenverteilungen von Yedoma-Ablagerungen verantwortlich sind. Vielmehr wird die Sedimentation der Yedoma-Ablagerungen eher durch lokale Bedingungen wie Ausgangsgesteine, ehemalige Topographie und multiple Transportprozesse gesteuert. Das stützt die Hypothese einer polygenetischen Yedoma-Entstehung, die alluvialen, fluvialen und nival-äolischen Transport und Akkumulation in polygonalen Tümpeln und in-situ Frostverwitterung sowie postsedimentäre Frostverwitterung, Solifluktion, Kryoturbation und Pedogenese beinhaltet. Die charakteristische rEM Zusammensetzung der Yedoma Cluster kann auch helfen korngrößenspezifische Parameter besser in der Kohlenstoffbudgetierung und Permafrostmodellierung zu berücksichtigen. Damit trägt die Charakterisierung und Quantifizierung standortspezifischer Ablagerungsprozesse in der Vergangenheit dazu bei, die charakteristischen Eigenschaften eisreicher Yedoma-Ablagerungen in der terrestrischen Arktis aufzuklären. Dies ist entscheidend für das Verständnis der Fortentwicklung dieses besonderen Permafrosttyps in einer wärmeren Zukunft.

Epic3, 2011

In the area of the Rostock-Leipzig-Regensburg fault zone (Germany) several centres of seismic act... more In the area of the Rostock-Leipzig-Regensburg fault zone (Germany) several centres of seismic activity are found with seismicity manifesting itself in swarm earthquakes. The occurrence of these earthquakes is globally linked to ascending magma and magmatic fluids. Information is scarce regarding the depth and geometry of the magmatic source, dynamics in the sub-Moho/lower crust region and fluid-tectonic processes in the

Near Surface Geophysics, 2010

nents, which led to the conclusion that the volcanic rock evolved from a primary Si-under saturat... more nents, which led to the conclusion that the volcanic rock evolved from a primary Si-under saturated, alkali-ultramafic initial melt (Kroner et al. 2006, Fig. 4). This 'structure' is situated in a region of uranium deposits and so it was mapped in detail during prospection campaigns of the SDAG Wismut (uranium industry in former East-Germany) in the 1970s. A compilation of geological features of the Ebersbrunn eruptive breccias for the last 40 years was published by Berger (2008). Recently, the structure came back into the focus of geophysical interest because it is situated close to locations of several swarm earthquakes that occurred in

Journal of Volcanology and Geothermal Research, 2009

Based on results of previous investigations of tephra-tuff volcaniclastic deposits and a geophysi... more Based on results of previous investigations of tephra-tuff volcaniclastic deposits and a geophysical survey in the surroundings of the Železná hůrka Quaternary volcano, West Bohemia, we performed detailed geophysical surveys using gravimetry, magnetometry and electrical conductivity techniques. Striking anomalies were revealed in a morphological depression near Mýtina, West Bohemia, as a strong evidence of the assumed maar-diatreme structure. The sharp isometric gravity low of − 2.30 mGal, as well as the corresponding positive magnetic anomaly of 200 nT with a negative rim on its northern side indicate a steeply dipping geological body of low density and containing magnetic rocks/minerals. Magnetic survey also showed pronounced local anomalies outside the depression that can reflect relicts of the tephra rim of the maar. This geophysical evidence was then proven by an exploratory drilling near the centre of the gravity anomaly. Macroscopic on-site evaluation of the core, and more detailed sedimentological, petrochemical, palynological and microbiological laboratory analyses further confirmed the existence of a maar structure filled by 84 m of lake sediments reflecting a succession of several warm and cold climatic periods. Results of palynological analyses confirm the presence of a continuous palaeoclimate archive, with at least three successive warmer periods of most probably interstadial character from the upper Quaternary Saalian complex. Therefore, the recovered sediment sequence holds strong potential for in-depth paleoclimate reconstruction and deep biosphere studies. At the bottom of the Mýtina-1 (MY-1) borehole (84-85.5 m), country rock debris was found, containing also volcanic bombs and lapilli. The discovered volcanic structure is considered to be the first known Quaternary maar-diatreme volcano on the territory of the Bohemian Massif. Because of hidden active magmatic processes in combination with earthquake swarm seismicity ca. 20-30 km north of the Mýtina maar, reconstruction of the palaeovolcanological evolution is important for evaluation of hazard potential of the NE and E part of the Cheb Basin.

The ESA DUE Permafrost project (2009-2011) is developing a suite of parameters indicative of the ... more The ESA DUE Permafrost project (2009-2011) is developing a suite of parameters indicative of the subsurface phenomenon permafrost using satellite remote sensing: Land Surface Temperature (LST), Surface Soil Moisture (SSM), Surface Frozen and Thawed State (Freeze/Thaw), Terrain, Land Cover (LC), and Surface Water (SW). Snow parameters (Snow Extent and Snow Water Equivalent) are being developed through the DUE GlobSnow project, Global Snow Monitoring for Climate Research (2008-2011). The final DUE Permafrost remote sensing products cover the years 2007 to 2011 with a circumpolar coverage that will soon be released (early 2012), and then be used to analyze the temporal dynamics and map the spatial patterns of indicators. Further information is available at www.ipf.tuwien.ac.at/ permafrost. Since the beginning, scientific stakeholders and the International Permafrost Association (IPA) have been involved in the science and implementation plan. Interactive international user workshops took place in 2010 at the Technical University of Vienna, Vienna (AT), and in 2011 at the International Arctic Research Center (IARC), Fairbanks, Alaska (US). This involvement and the ongoing evaluation of the indicators derived from remote sensing for the high-latitude permafrost regions make the DUE Permafrost products trustworthy for the permafrost and the climate research community. The adaption of the remote sensing products for the permafrost and climate modelling is experimental and highly dependent on the users’ involvement. For a few years already, the Geophysical Institute Permafrost Laboratory (GIPL), University of Alaska Fairbanks, US, (http://www.gi.alaska.edu/research/snowicepermafrost/Permafrost) has successfully demonstrated the value of using LST derived from remote sensing data for driving its permafrost models. Further experimental testing of the DUE Permafrost products for use by the modeling community (permafrost and climate) will range from (i) the evaluation of external data of the models, with modifying or providing new external data (e.g. tundra land cover, surface water ratio, soil distribution), to (ii) new drivers for regional models derived from remote sensing (e.g., LST), to (iii) the evaluation of the output data from the models (e.g. spatial patterns of moisture and temperature).

Polar Science , 2024

In this article, we identify what herders in Fennoscandia and northwestern Russia see as critical... more In this article, we identify what herders in Fennoscandia and northwestern Russia see as critical conditions and events in the annual reindeer herding cycle. Indigenous Sámi and Yamal reindeer herders identify eight seasons, each of which has crucial importance in its own way. Differences in perception between Fennoscandian and northwestern Russian reindeer herders about good and bad seasonal conditions are based on the degree of climatic and geographic variation, herd control and the variety of simultaneous pressures on pastures. The scope and speed of ongoing climate change in the Arctic will profoundly modify these conditions, and consequently shape critical events and outcomes in reindeer herding. The resulting challenges need to be assessed in the context of social and economic dynamics. Reindeer herders throughout Fennoscandia and Russia are concerned about future prospects of their livelihood. To adapt to climate change and develop new strategies, reindeer herders must have access to pastures; they must retain their mobility and flexibility; and their participation in land-use decisions must be endorsed.