scholarly journals Modelling the seasonal variations of soil temperatures in the Arctic coasts

Polar Science ◽  
2021 ◽  
pp. 100732
Author(s):  
Mohammad Akhsanul Islam ◽  
Raed Lubbad ◽  
Seyed Ali Ghoreishian Amiri ◽  
Vladislav Isaev ◽  
Yaroslav Shevchuk ◽  
...  
Keyword(s):  
Seasonal Variations ◽  
The Arctic ◽  
Soil Temperatures

Global mapping of seasonal variations in tides from tide gauge and satellite altimeter data

2021 ◽  
Author(s):  
Inger Bij de Vaate ◽  
Henrique Guarneri ◽  
Cornelis Slobbe ◽  
Martin Verlaan
Keyword(s):  
Seasonal Variation ◽  
Sea Level ◽  
Seasonal Variations ◽  
Large Scale ◽  
Arctic Region ◽  
The Arctic ◽  
Altimeter Data ◽  
Tide Gauges ◽  
Tidal Constituents ◽  
The Arctic Region

<p>The existence of seasonal variations in major tides has been recognized since decades. Where Corkan (1934) was the first to describe the seasonal perturbation of the M2 tide, many others have studied seasonal variations in the main tidal constituents since. However, most of these studies are based on sea level observations from tide gauges and are often restricted to coastal and shelf regions. Hence, observed seasonal variations are typically dominated by local processes and the large-scale patterns cannot be clearly distinguished. Moreover, most tide models still perceive tides as annually constant and seasonal variation in tides is ignored in the correction process of satellite altimetry. This results in reduced accuracy of obtained sea level anomalies. </p><p>To gain more insight in the large-scale seasonal variations in tides, we supplemented the clustered and sparsely distributed sea level observations from tide gauges by the wealth of data from satellite altimeters. Although altimeter-derived water levels are being widely used to obtain tidal constants, only few of these implementations consider seasonal variation in tides. For that reason, we have set out to explore the opportunities provided by altimeter data for deriving seasonal modulation of the main tidal constituents. Different methods were implemented and compared for the principal tidal constituents and a range of geographical domains, using data from a selection of satellite altimeters. Specific attention was paid to the Arctic region where seasonal variation in tides was expected to be significant as a result of the seasonal sea ice cycle, yet data availability is particularly limited. Our study demonstrates the potential of satellite altimetry for the quantification of seasonal modulation of tides and suggests the seasonal modulation to be considerable. Already for M2 we observed changes in tidal amplitude of the order of decimeters for the Arctic region, and centimeters for lower latitude regions.</p><p> </p><div>Corkan, R. H. (1934). An annual perturbation in the range of tide. <em>Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character</em>, <em>144</em>(853), 537-559.</div>

scholarly journals Environmental controls on ecosystem-scale cold-season methane and carbon dioxide fluxes in an Arctic tundra ecosystem

2020 ◽  
Vol 17 (15) ◽  
pp. 4025-4042
Author(s):  
Dean Howard ◽  
Yannick Agnan ◽  
Detlev Helmig ◽  
Yu Yang ◽  
Daniel Obrist
Keyword(s):  
Carbon Dioxide ◽  
Methane Emission ◽  
Arctic Tundra ◽  
Cold Season ◽  
The Arctic ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Carbon Dioxide Fluxes ◽  
Soil Temperatures ◽  
Annual Total

Abstract. Understanding the processes that influence and control carbon cycling in Arctic tundra ecosystems is essential for making accurate predictions about what role these ecosystems will play in potential future climate change scenarios. Particularly, air–surface fluxes of methane and carbon dioxide are of interest as recent observations suggest that the vast stores of soil carbon found in the Arctic tundra are becoming more available to release to the atmosphere in the form of these greenhouse gases. Further, harsh wintertime conditions and complex logistics have limited the number of year-round and cold-season studies and hence too our understanding of carbon cycle processes during these periods. We present here a two-year micrometeorological data set of methane and carbon dioxide fluxes, along with supporting soil pore gas profiles, that provide near-continuous data throughout the active summer and cold winter seasons. Net emission of methane and carbon dioxide in one of the study years totalled 3.7 and 89 g C m−2 a−1 respectively, with cold-season methane emission representing 54 % of the annual total. In the other year, net emission totals of methane and carbon dioxide were 4.9 and 485 g C m−2 a−1 respectively, with cold-season methane emission here representing 82 % of the annual total – a larger proportion than has been previously reported in the Arctic tundra. Regression tree analysis suggests that, due to relatively warmer air temperatures and deeper snow depths, deeper soil horizons – where most microbial methanogenic activity takes place – remained warm enough to maintain efficient methane production whilst surface soil temperatures were simultaneously cold enough to limit microbial methanotrophic activity. These results provide valuable insight into how a changing Arctic climate may impact methane emission, and highlight a need to focus on soil temperatures throughout the entire active soil profile, rather than rely on air temperature as a proxy for modelling temperature–methane flux dynamics.

Gas exchange and growth of three arctic tree-line tree species under different soil temperature and drought preconditioning regimes

1996 ◽  
Vol 74 (5) ◽  
pp. 686-693 ◽  
Author(s):  
Simon M. Landhäusser ◽  
Ross W. Wein ◽  
Petra Lange
Keyword(s):  
Soil Temperature ◽  
Picea Mariana ◽  
Tree Species ◽  
Withholding Treatment ◽  
The Arctic ◽  
Betula Papyrifera ◽  
Tree Line ◽  
Populus Balsamifera ◽  
Soil Temperatures ◽  
Net Assimilation

Low soil temperatures and water availability are thought to be major factors determining the distribution of tree species at the arctic tree line. A comparative study examined the response of Betula papyrifera, Populus balsamifera, and Picea mariana seedlings to different soil temperatures and drought regimes in a growth chamber experiment. Morphological and ecophysiological responses (net assimilation rate, stomatal conductance to water vapour, and residual conductance) of these tree line tree species were measured and compared. Mean biomass accumulation of the deciduous species was greater than that of Picea mariana with increasing soil temperatures. Root biomass showed an increase of 30% in the three species between the soil temperatures of 3 and 15 °C. Response of ecophysiological variables to increased soil temperature was greater in B. papyrifera and Populus balsamifera than in Picea mariana. In a second experiment, drought-preconditioned B. papyrifera and Populus balsamifera seedlings were subjected to a 6-day water-withholding treatment. Drought decreased shoot mass and increased the root to shoot ratio equally in B. papyrifera and Populus balsamifera. Drought-preconditioned B. papyrifera and Populus balsamifera seedlings responded differently to the 6-day water-withholding treatment. Betula papyrifera used a water-conserving strategy and maintained low net assimilation rates and low water use after drought preconditioning, whereas in Populus balsamifera greater net assimilation rates were associated with drought preconditioning. These results are consistent with the distribution of these three tree species at the arctic tree line. Keywords: Picea mariana, Populus balsamifera, Betula papyrifera, drought preconditioning, soil temperature, arctic tree line.

scholarly journals Simulation of permafrost and seasonal thaw depth in the JULES land surface scheme

2011 ◽  
Vol 5 (3) ◽  
pp. 773-790 ◽  
Author(s):  
R. Dankers ◽  
E. J. Burke ◽  
J. Price
Keyword(s):  
Land Surface ◽  
The Arctic ◽  
Soil Parameters ◽  
Active Layer Thickness ◽  
Organic Carbon Content ◽  
Land Surface Scheme ◽  
Spatial Coverage ◽  
Soil Temperatures ◽  
Thaw Depth ◽  
Surface Scheme

Abstract. Land surface models (LSMs) need to be able to simulate realistically the dynamics of permafrost and frozen ground. In this paper we evaluate the performance of the LSM JULES (Joint UK Land Environment Simulator), the stand-alone version of the land surface scheme used in Hadley Centre climate models, in simulating the large-scale distribution of surface permafrost. In particular we look at how well the model is able to simulate the seasonal thaw depth or active layer thickness (ALT). We performed a number of experiments driven by observation-based climate datasets. Visually there is a very good agreement between areas with permafrost in JULES and known permafrost distribution in the Northern Hemisphere, and the model captures 97% of the area where the spatial coverage of the permafrost is at least 50%. However, the model overestimates the total extent as it also simulates permafrost where it occurs sporadically or only in isolated patches. Consistent with this we find a cold bias in the simulated soil temperatures, especially in winter. However, when compared with observations on end-of-season thaw depth from around the Arctic, the ALT in JULES is generally too deep. Additional runs at three sites in Alaska demonstrate how uncertainties in the precipitation input affect the simulation of soil temperatures by affecting the thickness of the snowpack and therefore the thermal insulation in winter. In addition, changes in soil moisture content influence the thermodynamics of soil layers close to freezing. We also present results from three experiments in which the standard model setup was modified to improve physical realism of the simulations in permafrost regions. Extending the soil column to a depth of 60 m and adjusting the soil parameters for organic content had relatively little effect on the simulation of permafrost and ALT. A higher vertical resolution improves the simulation of ALT, although a considerable bias still remains. Future model development in JULES should focus on a dynamic coupling of soil organic carbon content and soil thermal and hydraulic properties, as well as allowing for sub-grid variability in soil types.

Den ecology of the Arctic fox in northern Alaska

1969 ◽  
Vol 47 (1) ◽  
pp. 121-129 ◽  
Author(s):  
David L. Chesemore
Keyword(s):  
Plant Growth ◽  
Soil Texture ◽  
Ice Core ◽  
The Arctic ◽  
Arctic Fox ◽  
Soil Temperatures ◽  
Alaskan Arctic ◽  
Northern Alaska ◽  
Teshekpuk Lake

During July and August 1962, 50 Arctic fox dens were studied on The Teshekpuk Lake Section of the Alaskan Arctic Slope. Depth to permafrost and soil texture govern location of fox dens in low. ice-core mounds with a minimum mound height of 1 m necessary for the establishment of a successful den. Soil temperatures at den sites were higher than those in nearby non-den habitats. The presence of the fox den alters plant growth near the burrow, changing the typical tundra community into a lush, vigorous one dominated by grasses.

Variations in the total column abundances of atmospheric carbon monoxide and methane in the polar regions

1991 ◽  
Vol 3 (4) ◽  
pp. 443-449 ◽  
Author(s):  
L.N. Yurganov ◽  
V.F. Radionov
Keyword(s):  
Carbon Monoxide ◽  
Seasonal Variations ◽  
The Arctic ◽  
Polar Regions ◽  
Atmospheric Carbon ◽  
Atmospheric Carbon Monoxide ◽  
The Antarctic ◽  
Total Column

Atmospheric carbon monoxide and methane were studied spectroscopically in the Arctic and Antarctic. Seasonal variations of CO are evident in both polar regions, absolute values of abundance being three times larger in the Arctic than in the Antarctic. Increasing concentration trends were confirmed for both gases: 0.8% per year for Antarctic CO, 0.5% per year for Antarctic CH4 and 3.1% per year for Arctic CH4.

scholarly journals The impact of microclimate and soil on the ecology and evolution of an arctic plant

2020 ◽  
Author(s):  
Niklas J. Wickander ◽  
Pil U. Rasmussen ◽  
Bryndís Marteinsdóttir ◽  
Johan Ehrlén ◽  
Ayco J. M. Tack
Keyword(s):  
Soil Temperature ◽  
Plant Species ◽  
Spatial Scales ◽  
The Arctic ◽  
Alpine Regions ◽  
High Soil ◽  
Evolutionary Response ◽  
Different Temperatures ◽  
Soil Temperatures ◽  
The Impact

AbstractThe arctic and alpine regions are predicted to experience one of the highest rates of climate change, and the arctic vegetation is expected to be especially sensitive to such changes. Understanding the ecological and evolutionary responses of arctic plant species to changes in climate is therefore a key objective. Geothermal areas, where temperature gradients naturally occur over small spatial scales, and without many of the confounding environmental factors present in latitudinal and other gradient studies, provide a natural experimental setting to examine the impact of temperature on the response of arctic-alpine plants to increasing temperatures. To test the ecological and evolutionary response of the circumpolar alpine bistort (Bistorta vivipara) to temperature, we collected plant material and soil from areas with low, intermediate, and high soil temperatures and grew them in all combinations at three different temperatures. At higher experimental soil temperatures, sprouting was earlier, and plants had more leaves. Sprouting was earlier in soil originating from intermediate temperature and plants had more leaves when grown in soil originating from low temperatures. We did not find evidence of local adaptation or genetic variation in reaction norms among plants originating from areas with low, intermediate, and high soil temperature. Our findings suggest that the alpine bistort has a strong plastic response to warming, but that differences in soil temperature have not resulted in genetic differentiation. The lack of an observed evolutionary response may, for example, be due to the absence of temperature-mediated selection on B. vivipara, or high levels of gene flow balancing differences in selection. When placed within the context of other studies, we conclude that arctic-alpine plant species often show strong plastic responses to spring warming, while evidence of evolutionary responses varies among species.

scholarly journals Environmental controls on ecosystem-scale cold season methane and carbon dioxide fluxes in an Arctic tundra ecosystem

2019 ◽  
Author(s):  
Dean Howard ◽  
Yannick Agnan ◽  
Detlev Helmig ◽  
Yu Yang ◽  
Daniel Obrist
Keyword(s):  
Carbon Dioxide ◽  
Methane Emission ◽  
Arctic Tundra ◽  
Cold Season ◽  
The Arctic ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Carbon Dioxide Fluxes ◽  
Soil Temperatures ◽  
Annual Total

Abstract. Understanding the processes that influence and control carbon cycling in Arctic tundra ecosystems is essential for making accurate predictions about what role these ecosystems will play in potential future climate change scenarios. Particularly, air–surface fluxes of methane and carbon dioxide are of interest as recent observations suggest that the vast stores of soil carbon found in the Arctic tundra are becoming more available to release to the atmosphere in the form of these greenhouse gases. Further, harsh wintertime conditions and complex logistics have limited the number of year-round and cold season studies and hence too our understanding of carbon cycle processes during these periods. We present here a two-year micrometeorological data set of methane and carbon dioxide fluxes that provides near-continuous data throughout the active summer and cold winter seasons. Net emission of methane and carbon dioxide in one of the study years totalled 3.7 and 89 g C m−2 a−1 respectively, with cold season methane emission representing 54% of the annual total. In the other year, net emission totals of methane and carbon dioxide were 4.9 and 485 g C m−2 a−1 respectively, with cold season methane emission here representing 82 % of the annual total – a larger proportion than has been previously reported in the Arctic tundra. Regression tree analysis suggests that, due to relatively warmer air temperatures and deeper snow depths, deeper soil horizons – where most microbial methanogenic activity takes place – remained warm enough to maintain efficient methane production whilst surface soil temperatures were simultaneously cold enough to limit microbial methanotrophic activity. These results provide valuable insight into how a changing Arctic climate may impact methane emission, and highlight a need to focus on soil temperatures throughout the entire active soil profile, rather than rely on air temperature as a proxy for modelling temperature–methane flux dynamics.

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