scholarly journals Spatial and Temporal Modelling of Biophysical Variables Within A High Arctic Wetland

2021 ◽  
Author(s):  
Gillian Ramasay
Keyword(s):  
Dynamic Systems ◽  
Temporal Variability ◽  
Hot Spots ◽  
Carbon Flux ◽  
Seasonal Changes ◽  
High Arctic ◽  
The Arctic ◽  
Layer Depth ◽  
Wetland Ecosystems ◽  
Temporal Modelling

The Arctic has experienced greater climate warming in the last decade than anywhere else, potentially shifting its carbon status from a sink to a source. Increasing temperatures impact nival wetlands that rely on a strong hydrological input from melting perennial snowpacks. Soil moisture, soil temperature and active layer depth are key biophysical variables in predicting carbon flux trajectories in this environment. How these variables interact is crucial in delineating links between snowmelt and seasonal changes in wetland productivity. To date, there have been numerous studies that have examined these variables, but few have investigated the relationships between these biophysical variables and wetland thaw patterns at a high spatial and temporal scale. This study found a decrease in temporal variability and reduced interactions between variables as the wetland thawed as well as localized hot spots of increased values and an overall east to west trend across the site. This implies that Arctic wetland ecosystems are dynamic systems that reach a level of stability during peak growth. They also exhibit changeable spatial patterns that cannot be generalized.

scholarly journals Spatial and Temporal Modelling of Biophysical Variables Within A High Arctic Wetland

2021 ◽  
Author(s):  
Gillian Ramasay
Keyword(s):  
Dynamic Systems ◽  
Temporal Variability ◽  
Hot Spots ◽  
Carbon Flux ◽  
Seasonal Changes ◽  
High Arctic ◽  
The Arctic ◽  
Layer Depth ◽  
Wetland Ecosystems ◽  
Temporal Modelling

The Arctic has experienced greater climate warming in the last decade than anywhere else, potentially shifting its carbon status from a sink to a source. Increasing temperatures impact nival wetlands that rely on a strong hydrological input from melting perennial snowpacks. Soil moisture, soil temperature and active layer depth are key biophysical variables in predicting carbon flux trajectories in this environment. How these variables interact is crucial in delineating links between snowmelt and seasonal changes in wetland productivity. To date, there have been numerous studies that have examined these variables, but few have investigated the relationships between these biophysical variables and wetland thaw patterns at a high spatial and temporal scale. This study found a decrease in temporal variability and reduced interactions between variables as the wetland thawed as well as localized hot spots of increased values and an overall east to west trend across the site. This implies that Arctic wetland ecosystems are dynamic systems that reach a level of stability during peak growth. They also exhibit changeable spatial patterns that cannot be generalized.

Summer phytoplankton of the northern Barents Sea (75–80º N)

2019 ◽  
pp. 8-19
Author(s):  
Larisa A. Pautova ◽  
Vladimir A. Silkin ◽  
Marina D. Kravchishina ◽  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Weighted Average ◽  
Arctic Basin ◽  
High Arctic ◽  
Alexandrium Tamarense ◽  
Warm Water ◽  
The Arctic ◽  
Absolute Maximum ◽  
Deep Trench ◽  
Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

scholarly journals Characterization of Transport Regimes and the Polar Dome during Arctic Spring and Summer using in-situ Aircraft Measurements

2019 ◽  
Author(s):  
Heiko Bozem ◽  
Peter Hoor ◽  
Daniel Kunkel ◽  
Franziska Köllner ◽  
Johannes Schneider ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
High Arctic ◽  
The Arctic ◽  
Trace Gas ◽  
Second Phase ◽  
Aerosol Formation ◽  
Transport Barrier ◽  
Data Set ◽  
Air Masses ◽  
Mixing Ratios

Abstract. The springtime composition of the Arctic lower troposphere is to a large extent controlled by transport of mid-latitude air masses into the Arctic, whereas during the summer precipitation and natural sources play the most important role. Within the Arctic region, there exists a transport barrier, known as the polar dome, which results from sloping isentropes. The polar dome, which varies in space and time, exhibits a strong influence on the transport of air masses from mid-latitudes, enhancing it during winter and inhibiting it during summer. Furthermore, a definition for the location of the polar dome boundary itself is quite sparse in the literature. We analyzed aircraft based trace gas measurements in the Arctic during two NETCARE airborne field camapigns (July 2014 and April 2015) with the Polar 6 aircraft of Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI), Bremerhaven, Germany, covering an area from Spitsbergen to Alaska (134° W to 17° W and 68° N to 83° N). For the spring (April 2015) and summer (July 2014) season we analyzed transport regimes of mid-latitude air masses travelling to the high Arctic based on CO and CO2 measurements as well as kinematic 10-day back trajectories. The dynamical isolation of the high Arctic lower troposphere caused by the transport barrier leads to gradients of chemical tracers reflecting different local chemical life times and sources and sinks. Particularly gradients of CO and CO2 allowed for a trace gas based definition of the polar dome boundary for the two measurement periods with pronounced seasonal differences. For both campaigns a transition zone rather than a sharp boundary was derived. For July 2014 the polar dome boundary was determined to be 73.5° N latitude and 299–303.5 K potential temperature, respectively. During April 2015 the polar dome boundary was on average located at 66–68.5° N and 283.5–287.5 K. Tracer-tracer scatter plots and probability density functions confirm different air mass properties inside and outside of the polar dome for the July 2014 and April 2015 data set. Using the tracer derived polar dome boundaries the analysis of aerosol data indicates secondary aerosol formation events in the clean summertime polar dome. Synoptic-scale weather systems frequently disturb this transport barrier and foster exchange between air masses from midlatitudes and polar regions. During the second phase of the NETCARE 2014 measurements a pronounced low pressure system south of Resolute Bay brought inflow from southern latitudes that pushed the polar dome northward and significantly affected trace gas mixing ratios in the measurement region. Mean CO mixing ratios increased from 77.9 ± 2.5 ppbv to 84.9 ± 4.7 ppbv from the first period to the second period. At the same time CO2 mixing ratios significantly dropped from 398.16 ± 1.01 ppmv to 393.81 ± 2.25 ppmv. We further analysed processes controlling the recent transport history of air masses within and outside the polar dome. Air masses within the spring time polar dome mainly experienced diabatic cooling while travelling over cold surfaces. In contrast air masses in the summertime polar dome were diabatically heated due to insolation. During both seasons air masses outside the polar dome slowly descended into the Arctic lower troposphere from above caused by radiative cooling. The ascent to the middle and upper troposphere mainly took place outside the Arctic, followed by a northward motion. Our results demonstrate the successful application of a tracer based diagnostic to determine the location of the polar dome boundary.

scholarly journals Metagenomic Analysis of Stress Genes in Microbial Mat Communities from Antarctica and the High Arctic

2011 ◽  
Vol 78 (2) ◽  
pp. 549-559 ◽  
Author(s):  
Thibault Varin ◽  
Connie Lovejoy ◽  
Anne D. Jungblut ◽  
Warwick F. Vincent ◽  
Jacques Corbeil
Keyword(s):  
High Arctic ◽  
Environmental Stresses ◽  
The Arctic ◽  
Functional Responses ◽  
Protein Coding ◽  
Content Type ◽  
Stress Genes ◽  
Cyanobacterial Genes ◽  
Shock Proteins ◽  
The Antarctic

ABSTRACTPolar and alpine microbial communities experience a variety of environmental stresses, including perennial cold and freezing; however, knowledge of genomic responses to such conditions is still rudimentary. We analyzed the metagenomes of cyanobacterial mats from Arctic and Antarctic ice shelves, using high-throughput pyrosequencing to test the hypotheses that consortia from these extreme polar habitats were similar in terms of major phyla and subphyla and consequently in their potential responses to environmental stresses. Statistical comparisons of the protein-coding genes showed similarities between the mats from the two poles, with the majority of genes derived fromProteobacteriaandCyanobacteria; however, the relative proportions differed, with cyanobacterial genes more prevalent in the Antarctic mat metagenome. Other differences included a higher representation ofActinobacteriaandAlphaproteobacteriain the Arctic metagenomes, which may reflect the greater access to diasporas from both adjacent ice-free lands and the open ocean. Genes coding for functional responses to environmental stress (exopolysaccharides, cold shock proteins, and membrane modifications) were found in all of the metagenomes. However, in keeping with the greater exposure of the Arctic to long-range pollutants, sequences assigned to copper homeostasis genes were statistically (30%) more abundant in the Arctic samples. In contrast, more reads matching the sigma B genes were identified in the Antarctic mat, likely reflecting the more severe osmotic stress during freeze-up of the Antarctic ponds. This study underscores the presence of diverse mechanisms of adaptation to cold and other stresses in polar mats, consistent with the proportional representation of major bacterial groups.

scholarly journals The Rossby radius in the Arctic Ocean

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 967-975 ◽  
Author(s):  
A. J. G. Nurser ◽  
S. Bacon
Keyword(s):  
Arctic Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
High Arctic ◽  
The Arctic ◽  
Hudson Bay ◽  
Ocean Eddies ◽  
Shelf Seas ◽  
The Impact

Abstract. The first (and second) baroclinic deformation (or Rossby) radii are presented north of ~60° N, focusing on deep basins and shelf seas in the high Arctic Ocean, the Nordic seas, Baffin Bay, Hudson Bay and the Canadian Arctic Archipelago, derived from climatological ocean data. In the high Arctic Ocean, the first Rossby radius increases from ~5 km in the Nansen Basin to ~15 km in the central Canadian Basin. In the shelf seas and elsewhere, values are low (1–7 km), reflecting weak density stratification, shallow water, or both. Seasonality strongly impacts the Rossby radius only in shallow seas, where winter homogenization of the water column can reduce it to below 1 km. Greater detail is seen in the output from an ice–ocean general circulation model, of higher resolution than the climatology. To assess the impact of secular variability, 10 years (2003–2012) of hydrographic stations along 150° W in the Beaufort Gyre are also analysed. The first-mode Rossby radius increases over this period by ~20%. Finally, we review the observed scales of Arctic Ocean eddies.

scholarly journals Numerical investigation of the Arctic ice-ocean boundary layer; implications for air-sea gas fluxes

2016 ◽  
Author(s):  
A. Bigdeli ◽  
B. Loose ◽  
S. T. Cole
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
The Arctic ◽  
Layer Depth ◽  
Near Surface ◽  
Resolution Model ◽  
Simplifying Assumptions ◽  
Vertical Spacing

Abstract. In ice-covered regions it can be challenging to determine air-sea exchange – for heat and momentum, but also for gases like carbon dioxide and methane. The harsh environment and relative data scarcity make it difficult to characterize even the physical properties of the ocean surface. Here, we seek a mechanistic interpretation for the rate of air-sea gas exchange (k) derived from radon-deficits. These require an estimate of the water column history extending 30 days prior to sampling. We used coarse resolution (36 km) regional configuration of the MITgcm with fine near surface vertical spacing (2 m) to evaluate the capability of the model to reproduce conditions prior to sampling. The model is used to estimate sea-ice velocity, concentration and mixed-layer depth experienced by the water column. We then compared the model results to existing field data including satellite, moorings and Ice-tethered profilers. We found that model-derived sea-ice coverage is 88 to 98 % accurate averaged over Beaufort Gyre, sea-ice velocities have 78 % correlation which resulted in 2 km/day error in 30 day trajectory of sea-ice. The model demonstrated the capacity to capture the broad trends in the mixed layer although with a bias and model water velocities showed only 29 % correlation with actual data. Overall, we find the course resolution model to be an inadequate surrogate for sparse data, however the simulation results are a slight improvement over several of the simplifying assumptions that are often made when surface ocean geochemistry, including the use of a constant mixed layer depth and a velocity profile that is purely wind-driven.

scholarly journals On the chemical dynamics of extracellular polysaccharides in the high Arctic surface microlayer

Ocean Science ◽  
2012 ◽  
Vol 8 (4) ◽  
pp. 401-418 ◽  
Author(s):  
Q. Gao ◽  
C. Leck ◽  
C. Rauschenberg ◽  
P. A. Matrai
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Compositional Analysis ◽  
Physicochemical Characteristics ◽  
High Arctic ◽  
The Arctic ◽  
Extracellular Polysaccharides ◽  
Surface Microlayer ◽  
Biological Origin ◽  
Ocean Study

Abstract. The surface microlayer (SML) represents a unique system of which the physicochemical characteristics may differ from those of the underlying subsurface seawater (SSW). Within the Arctic pack ice area, the SML has been characterized as enriched in small colloids of biological origin, resulting from extracellular polymeric secretions (EPS). During the Arctic Summer Cloud Ocean Study (ASCOS) in August 2008, particulate organic matter (POM, with size range > 0.22 μm) and dissolved organic matter (DOM, < 0.22 μm, obtained after filtration) samples were collected and chemically characterized from the SML and the corresponding SSW at an open lead centered at 87.5° N and 5° E. Total organic carbon was persistently enriched in the SML with a mean enrichment factor (EF) of 1.45 ± 0.41, whereas sporadic depletions of dissolved carbohydrates and amino acids were observed. Monosaccharide compositional analysis reveals that EPS in the Arctic lead was formed mainly of distinctive heteropolysaccharides, enriched in xylose, fucose and glucose. The mean concentrations of total hydrolysable neutral sugars in SSW were 94.9 ± 37.5 nM in high molecular weight (HMW) DOM (> 5 kDa) and 64.4 ± 14.5 nM in POM. The enrichment of polysaccharides in the SML appeared to be a common feature, with EFs ranging from 1.7 to 7.0 for particulate polysaccharides and 3.5 to 12.1 for polysaccharides in the HMW DOM fraction. A calculated monosaccharide yield suggests that polymers in the HMW DOM fraction were scavenged, without substantial degradation, into the SML. Bubble scavenging experiments showed that newly aggregated particles could be formed abiotically by coagulation of low molecular weight nanometer-sized gels. Aerosol particles, artificially generated by bubbling experiments, were enriched in polysaccharides by factors of 22–70, relative to the source seawater. We propose that bubble scavenging of surface-active polysaccharides could be one of the possible mechanisms for the enrichment of polysaccharides in the high Arctic open lead SML.

Sign in / Sign up

Export Citation Format

Share Document