Download or read book Large scale Measurements of Net CO2 Flux and Energy Balance of Alaskan Arctic Tundra Ecosystems written by and published by . This book was released on 1997 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Temporal and Spatial Analysis of the Patterns and Controls on Carbon Dioxide Water Vapor and Energy Fluxes in the Alaskan Arctic Tundra written by Hyojung Kwon and published by . This book was released on 2005 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Temporal and spatial variability in the Arctic introduces considerable uncertainty in estimations of the current carbon and energy budget and Arctic ecosystem response to climate change. Few representative measurements are available for land-surface parameterization of the Arctic tundra in regional and global climate models. Continuous measurements of net ecosystem CO 2 exchange (NEE), water vapor, and energy exchange using the eddy covariance technique were conducted in Alaskan wet sedge tundra and moist tussock tundra during the summer seasons (June 1--August 31) from 1999 to 2003 in order to quantify seasonal and spatial NEE, water vapor, and energy fluxes and to assess primary controlling factors which drive the change in the fluxes for the Arctic tundra ecosystems. At the wet sedge tundra, seasonal variation in energy balance was substantial, indicating ground heat flux (G) was significant during the snow-melt and post-snowmelt periods, whereas sensible heat flux (H) was dominant during the plant growth. During the measurement periods, H was the main energy component comprising 52% of net radiation (R n), followed by latent heat flux (LE) at 26% and G representing 8% of R n . The energy balance and evapotranspiration were strongly influenced by the maritime climate that brought cold, humid air to the site. Warmer and drier conditions prevailed for the moist tussock tundra compared with that of the wet sedge tundra. The wet sedge tundra was a sink for carbon of 46.4 to 70.0 gC m -2 season -1, while the moist tussock tundra either lost carbon of up to 60.8 gC m -2 season -1 or was in balance. The wet sedge tundra showed an acclimation (e.g., over days) to temperature, while the moist tussock tundra illustrated a strong temperature dependence. Warming and drying accentuated ecosystem respiration in the moist tussock tundra causing a net loss of carbon. The contrasting patterns of carbon balance at the two sites demonstrate that spatial variability can be more important in landscape NEE than intra- and inter-seasonal variability due to environmental factors with respect to NEE. Better characterization of spatial variability in NEE and associated environmental controls is required to improve current and future predictions of the Arctic terrestrial carbon balance.

Download or read book Response of a Tundra Ecosystem to Elevated Atmospheric Carbon Dioxide and CO2 induced Climate Change Annual Technical Report written by and published by . This book was released on 1993 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Northern ecosystems contain up to 455 Gt of C in the soil active layer and upper permafrost, which is equivalent to approximately 60% of the carbon currently in the atmosphere as CO2. Much of this carbon is stored in the soil as dead organic matter. Its fate is subject to the net effects of global change on the plant and soil systems of northern ecosystems. The arctic alone contains about 60 Gt C, 90% of which is present in the soil active layer and upper permafrost, and is assumed to have been a sink for CO2 during the historic and recent geologic past. Depending on the nature, rate, and magnitude of global environmental change, the arctic may have a positive or negative feedback on global change. Results from the DOE- funded research efforts of 1990 and 1991 indicate that the arctic has become a source of CO2 to the atmosphere. Measurements made in the Barrow, Alaska region during 1992 support these results. This change coincides with recent climatic variation in the arctic, and suggests a positive feedback of arctic ecosystems on atmospheric CO2 and global change. There are obvious potential errors in scaling plot level measurements to landscape, mesoscale, and global spatial scales. In light of the results from the recent DOE-funded research, and the remaining uncertainties regarding the change in arctic ecosystem function due to high latitude warming, a revised set of research goals is proposed for the 1993--94 year. The research proposed in this application has four principal aspects: (A) Long- term response of arctic plants and ecosystems to elevated atmospheric CO2. (B) Circumpolar patterns of net ecosystem CO2 flux. (C) In situ controls by temperature and moisture on net ecosystem CO2 flux. (D) Scaling of CO2 flux from plot, to landscape, to regional scales.

Download or read book Response of a Tundra Ecosystem to Elevated Atmospheric Carbon Dioxide and CO2 induced Climate Change Final Report written by and published by . This book was released on 1996 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this research was to document current patterns of CO2 flux in selected locations of the circumpolar arctic, and to develop the information necessary to predict how these fluxes may be affected by climate change. In fulfillment of these objectives, net CO2 flux was measured at several sites on the North Slope of Alaska during the 1990--94 growing season (June--August) to determine the local and regional patterns of seasonal CO2 exchange. In addition, net CO2 flux was measured in the Russian and Icelandic Arctic to determine if the patterns of CO2 exchange observed in Arctic Alaska were representative of the circumpolar Arctic, while cold-season CO2 flux measurements were carried out during the 1993--94 winter season to determine the magnitude of CO2 efflux not accounted for by the growing season measurements. Manipulations of soil water table depth and surface temperature, which were identified from the extensive measurements as being the most important variables in determining the magnitude and direction of net CO2 exchange, were carried out during the 1993--94 growing seasons in tussock and wet sedge tundra ecosystems. Finally, measurements of CH4 flux were also measured at several of the North Slope study sites during the 1990--91 growing seasons.

Download or read book Response of a Tundra Ecosystem to Elevated Atmospheric Carbon Dioxide and CO2 induced Climate Change Post field Season Work Plan September 1 1994 November 30 1994 written by and published by . This book was released on 1994 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The preliminary data from the temperature and water table manipulations indicated that net CO2 flux of both tussock and wet sedge tundra ecosystems is sensitive to changes in water table depth and soil temperature. The preliminary results from the patch, landscape, and regional flux measurements indicate that there are large deficiencies in our current ability to extrapolate from patch and landscape levels to the region. During fall 1994, our primary goals are to: (1) Analyze a full season of net CO2 flux from the in situ manipulations, and determine the effects of water table depth and elevated temperature on the C balance of arctic ecosystems. Once this task is complete, the data will be published in a form that discusses the importance of these environmental controls, and their relevance to future CO2-induced climate change. (2) Analyze tower- and aircraft-based eddy correlation flux data, and develop methods to reduce the time required to analyze these data. (3) Determine the importance of environmental controls of the exchange of CO2 at each spatial scale, and to develop the necessary routines that will permit the scaling of fine-scale flux data to landscape and regional scales. (4) Prepare manuscripts for publication on net CO2 flux data for each spatial scale, latitudinal flux pattern, and on methods and considerations for scaling from point measurements to the landscape and regional scale.

Download or read book Der Austausch Von Energie Wasser und Kohlendioxid Zwischen Arktischer Feuchtgebiets Tundra und Der Atmosph re Im Nordsibirischen Lena Delta written by Lars Kutzbach and published by . This book was released on 2006 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Response of a Tundra Ecosytem to Elevated Atmospheric Carbon Dioxide and CO2 induced Climate Change Final Report written by and published by . This book was released on 1996 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this research was to document current patterns of CO2 flux in selected locations of the circumpolar arctic, and to develop the information necessary to predict how these fluxes may be affected by climate change. In fulfillment of these objectives, net CO2 flux was measured at several sites on the North Slope of Alaska during the 1990-94 growing season (June-August) to determine the local and regional patterns, of seasonal CO2 exchange. In addition, net CO2 flux was measured in the Russian and Icelandic Arctic to determine if the patterns of CO2 exchange observed in Arctic Alaska were representative of the circumpolar arctic, while cold-season CO2 flux measurements were carried out during the 1993-94 winter season to determine the magnitude of CO2 efflux not accounted for by the growing season measurements. Manipulations of soil water table depth and surface temperature, which were identified from the extensive measurements as being the most important variables in determining the magnitude and direction of net CO2 exchange, were carried out during the 1993-94 growing seasons in tussock and wet sedge tundra ecosystems. Finally, measurements of CH4 flux were also measured at several of the North Slope study sites during the 1990-91 growing seasons. Measurements were made on small (e.g. 0.5 m2) plots using a portable gas-exchange system and cuvette. The sample design allowed frequent measurements of net CO2 exchange and respiration over diurnal and seasonal cycles, and a large spatial extent that incorporated both locally and regionally diverse tundra surface types. Measurements both within and between ecosystem types typically extended over soil water table depth and temperature gradients, allowing for the indirect analysis of the effects of anticipated climate change scenarios on net CO2 exchange. In situ experiments provided a direct means for testing hypotheses.

Download or read book Landscape Function and Disturbance in Arctic Tundra written by James F. Reynolds and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following the discovery of large petroleum reserves in northern Alaska, the US Department of Energy implemented an integrated field and modeling study to help define potential impacts of energy-related disturbances on tundra ecosystems. This volume presents the major findings from this study, ranging from ecosystem physiology and biogeochemistry to landscape models that quantify the impact of road-building. An important resource for researchers and students interested in arctic ecology, as well as for environmental managers concerned with practical issues of disturbances.

Download or read book Seasonal Impacts of Climate Change on the Carbon Balance of Alaskan Arctic Tundra Ecosystems written by Kyle A. Arndt and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arctic ecosystems are warming at a rate twice that of the global mean with winters warming faster than the rest of the year. With short, relatively productive summers and freezing cold winters, the Arctic has been a long-term carbon sink, but that is changing. Until recently, measurements scarcely existed outside of the summer growing season and winters have been assumed negligible. But as data coverage increases, estimates show the cold season may release 1662 Tg of carbon per year, greater than summer uptake of 1,032 Tg of carbon based on process models. Here, I analyze dynamics that make up year-round carbon budget using a multi-faceted approach including eddy covariance and satellite imagery. I show that soil is staying unfrozen for longer periods in the fall (2.6 ± 0.5 days y−1 from 2001 to 2017), correlated to methane enhancements on the Alaska North Slope (0.79 ± 0.18 ppb CH4 day−1 unfrozen soil). This longterm temperature trend and elevated methane could be related to vegetation changes as well given the carbon dynamics are further controlled by vegetation communities. To address this, I analyzed fine scale trends of vegetation productivity showing an increase in NDVI over a similar timescale from 2002-2016 ([tau] = 0.65, p = 0.01, NDVI increase of 0.01 yr−1 ), which was correlated to earlier thaws (R2 = 0.77, F = 21.5, p

Download or read book Effects of Vegetation Soil Moisture and Ecosystem Development on Landscape scale CO2 and CH4 Exchange from Arctic Coastal Tundra written by and published by . This book was released on 2013 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic is rapidly changing as a result of climate forcing induced by rising greenhouse gas concentrations. Given the large soil organic carbon pools of this biome, understanding how potential changes to arctic ecosystems will affect the Arctic's net carbon balance is imperative for improving predictions of future global climate. However, complicating this understanding is the large heterogeneity of arctic landscapes. There is currently the need for more wholeecosystem studies not only to improve regional flux estimates but also to determine how smallscale variability integrates to form the whole-ecosystem response to climate-induced changes in tundra conditions. This dissertation addresses this research need with a combination of regionalscale observations and whole-ecosystem moisture experimentation in the arctic coastal tundra near Barrow, Alaska. Regional-scale variability in cumulative growing season net CO2 exchange (NEE) was very large and was strongly tied to declining productivity associated with ecosystem development across the dominant landscape unit: thaw lakes and an age sequence of drained thaw lake basins. Contrary to many previous small-scale studies, moisture (aside from lakes) was not a dominant factor controlling regional-scale variability in NEE. However, this result was supported by a study of whole-ecosystem NEE and ecosystem respiration (ER) in a large-scale moisture manipulation experiment. This study confirmed what the few previous large-scale experiments have found: that increased wetness does not necessarily reduce ER and increase carbon storage. Furthermore, the release to the atmosphere of respired CO2 in moist and wet conditions was strongly enhanced by increased wind speed. This effect was shown to be largely missed by small-scale chamber measurements and is currently inadequately considered in commonly used models to partition ER from NEE determined by eddy covariance. Landscapescale variability in CH4 emissions was also large, but was mostly controlled by ecosystem moisture status and had very little relation to ecosystem development or productivity, identifying contrasting patterns and controls on fluxes of CO2 and CH4. The large control of CH4 flux variability by soil moisture was confirmed by the large-scale moisture manipulation experiment in which an experimentally raised water table resulted in higher CH4 emission. This experiment identified further control of moisture on autumn CH4 emissions, linking the decline in autumn CH4 emissions to the decline in liquid moisture during soil freezing. A higher water table slowed the soil freezing process, prolonging higher CH4 emissions later into the autumn and early winter. Combined, these results indicate that the variability in CO2 and CH4 emissions is large but can be explained and predicted in order to improve and validate regional flux models. Taken together, these results suggest that increased soil moisture in arctic areas may increase both CO2 and CH4 emissions, while increased lake drainage could turn strong CO2 source areas into large CO2 sinks as vegetation develops and soil organic matter accumulates.

Download or read book Response of a Tundra Ecosystem to Elevated Atmospheric Carbon Dioxide and CO2 induced Climate Change Annual Report written by and published by . This book was released on 1991 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: This renewal represents a continuation request for the third year of our current research program. While this renewal follows the original research proposed, it is modified to reflect information gained in the first two years of the project. Important findings of the last 12 months include the fact that carbon is being lost as CO2 from most sites measured along a latitudinal transect from Toolik Lake to Prudhoe Bay, Alaska. All locations measured but one showed a net loss of carbon as CO2 to the atmosphere. The drier sites tended to show greater rates of carbon loss. The only site showing net carbon accumulation was the wettest tussock tundra site measured. The average rate of loss for all sites was about 180 g C m−2 y−2, or about 0.2 GtC y−1 for the circumpolar wet sedge tundra and tussock tundra combined. This observation fits well with the conclusion of Tans et al. (1990) that there is currently a high latitude terrestrial source of CO2 to the atmosphere. These high rates of carbon loss, combined with the very large store of carbon in northern ecosystems (about 500 GtC) suggested that the current rates of carbon loss from arctic tundra to the atmosphere should be further examined. This includes analysis of the temporal and spatial pattern of carbon flux, the pattern of carbon flux for different vegetation types and micro-habitats, and the moisture and temperature controls on ecosystem carbon loss to the atmosphere.

Download or read book Spatial and Temporal Patterns of Carbon Exchange in the Alaskan Arctic Tundra Ecosystem written by and published by . This book was released on 2010 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focuses on the spatial and temporal patterns of, and controls on, CO2 in the Alaskan Arctic tundra ecosystem. The sites investigated--wet sedge, moist acidic, and low tussock tundra--represent the dominant land cover types in the Arctic tundra ecosystem, yet none have previously been investigated continuously throughout the year. In the first part of the research presented here, new definitions of season are presented, which will allow better comparisons across sites, seasons, and years in the Arctic tundra, where season length varies among years and locations. The results of this, the first, continuous, yearlong Arctic tundra study in a moist acidic tundra region, show that while summer uptake was detected ( -11 g C m−2 yr−1), the annual carbon signal was overwhelmed by the non-summer seasons, resulting in a net annual carbon release of nearly 38 g C m−2 yr−1. Winter showed low metabolic rates over a long season resulting in a net source of carbon to the atmosphere. The transitional seasons of spring and fall demonstrated active rates over short durations and were also sources of carbon to the atmosphere. In addition to the variable pattern of carbon exchange, the controls on carbon varied by season as well. For example, the effect of increasing soil temperature was negatively related to net ecosystem exchange (NEE) during winter and summer, but positively related to NEE during spring and fall. These results indicate that continuous monitoring of carbon, and related environmental variables, is important in accurate estimation of the current total annual and seasonal carbon budgets. This information, in turn, is critical to our ability to predict, with confidence, future carbon budgets. In the second part of the research, three years of continuous carbon measurements are presented for a low tussock tundra region. This southern site is especially vulnerable to climate change effects because it is at the southern extent of the tundra ecosystem near the graminoid-shrub boundary and increased rates of decomposition, and the region is likely to undergo community compositional changes in the near future. This region is likely to experience deeper active layers in the future, potentially exposing large stocks of carbon. This southern system was a net source of carbon over the three-year period of study, with only two of the three summer seasons acting as net carbon sinks. In one year, drought was so severe that even during the summer season, respiration overwhelmed photosynthesis, leading to a large (87 g C m−2 yr−1) annual efflux compared to the other years of the study (which had 0.04 and 49 g C m−2 yr−1 annual carbon release). In the last part of this research, NEE was measured at three sites located along a latitudinal gradient that spanned the North Slope of Alaska. Only in the northernmost site at Barrow was net annual carbon uptake detected, leading to an average uptake rate of 80 g C m−2 yr−1. Increased temperatures and decreased rainfall led to greater uptake in this, the coldest and least well drained of the sites. The two inland sites were both net sources of carbon to the atmosphere over the three-year period, resulting in an average of 30 and 45 g C m−2 yr−1 at each of the sites. Site differences were the primary controls on carbon variation among the sites, but inter and intra-annual variation were also significant. These data represent the first continuous measurements in the Arctic tundra ecosystem, and highlight the high degree of heterogeneity in the tundra ecosystem. These data may be used to validate and further develop climate and ecosystem models and to more accurately depict the variability, both spatially and temporally, in the Arctic tundra ecosystem.

Download or read book Patterns and Controls on Methane and Carbon Dioxide Fluxes on the Arctic Coastal Plain Alaska written by Donatella Zona and published by . This book was released on 2009 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: My research focuses on the patterns and controls of CO2 and CH4 fluxes in vegetated drained lake basins on the Arctic Coastal Plain in northern Alaska. These land features account for the majority of the landscape in the Arctic Coastal Plain, but have never been systematically investigated with respect to their impact on trace gas fluxes in the global carbon budget. In the first part of my research I focused on the impacts of water table change on CO2 and CH4 fluxes in a vegetated drained lake basin, where the water table was manipulated. I showed that the water table drop below the surface may not decrease CH4 emissions if a simultaneous increase in thaw depth increases the soil volume available for methanogenesis. On the other hand, an increase in water table above the surface could increase the diffusive resistance to CH4 release and decrease its emission. The impact of water table increase on CO2 was also surprising. Contrary to the common prediction, I demonstrated that increasing the water table level can increase CO2 injection into the atmosphere. This CO2 loss from the ecosystem is likely due to an increase in respiration, for the increase soil volume in the flood area, and decrease in light at the level of the photosynthetic organs. In the last part of my research, I study the carbon dynamics of a number of vegetated drained lake basins, which drained from 50 to 2000 years ago, in the Arctic Coastal Plain. I characterized 12 vegetated drained lake basins in terms of net ecosystem exchange (NEE), ecosystem respiration (ER) and gross primary production (GPP), and investigated the seasonal patterns and environmental controls on CO2 fluxes. The comparison of the seasonal CO2 fluxes in vegetated drained lake basins of different age allowed me to test the validity of the traditional view that net primary production decreases with ecosystem maturity . I showed that ecosystems thousands of years old (i.e. old vegetated drained lake basins are still a CO2 sink in the global carbon budget.

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1020 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Net Emissions of Methane and Carbon Dioxide in Alaska written by Qianlai Zhuang and published by . This book was released on 2007 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to study the net methane (CH4) fluxes between Alaskan ecosystems and the atmosphere. We estimated that the current net emissions of CH4 (emissions minus consumption) from Alaskan soils are ~3 Tg CH4/yr. Wet tundra ecosystems are responsible for 75% of the region's net emissions, while dry tundra and upland boreal forests are responsible for 50% and 45% of total consumption over the region, respectively. In response to climate change over the 21st century, our simulations indicated that CH4 emissions from wet soils would be enhanced more than consumption by dry soils of tundra and boreal forests. As a consequence, we projected that net CH4 emissions will almost double by the end of the century in response to high-latitude warming and associated climate changes. When we placed these CH4 emissions in the context of the projected carbon budget (carbon dioxide [CO2] and CH4) for Alaska at the end of the 21st century, we estimated that Alaska will be a net source of greenhouse gases to the atmosphere of 69 Tg CO2 equivalents/yr, that is, a balance between net methane emissions of 131 Tg CO2 equivalents/yr and carbon sequestration of 17 Tg C/yr (62 Tg CO2 equivalents/yr).

Download or read book Handbook of Micrometeorology written by Xuhui Lee and published by Springer Science & Business Media. This book was released on 2006-01-20 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Micrometeorology is the most up-to-date reference for micrometeorological issues and methods related to the eddy covariance technique for estimating mass and energy exchange between the terrestrial biosphere and the atmosphere. It provides useful insight for interpreting estimates of mass and energy exchange and understanding the role of the terrestrial biosphere in global environmental change.

Download or read book Analysis of the Surface Energy Budget of a Low Arctic Valley Within the Forest tundra Ecotone written by Georg Lackner and published by . This book was released on 2021 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: The forest-tundra ecotone (FTE) is an environment where the boreal forest begins a transition to the arctic tundra. With an extent of about 13,400 km, this interface is probably the largest transition zone on Earth and covers large parts of northern Eurasia and North America. Its size makes it a factor of increasing importance for the Earth’s climate with global warming. Indeed,the very different properties of forest and tundra are reflected in the surface energy balance,which describes the energy and mass exchanges at the soil-atmosphere interface. In short, this balance reflects the distribution of net radiation into sensible and latent heat fluxes, as well as heat fluxes into the soil. To date, this balance has been little studied in the FTE, despite its crucial role in coupling the atmosphere and the soil which is essential for the thermal and hydrological regime of the land surface. The objective of this study is to analyze the surface energy balance at a Low-Arctic site in the FTE, on the east coast of Hudson Bay in eastern Canada, in summer and winter. To do so, we use data collected by a micrometeorological tower using the eddy covariance approach. The study site is the Tasiapik valley, 4.5 km long,where the upper parts of the valley are covered by shrub tundra that transforms into a boreal forest towards the lower parts of the valley. In addition, we compare the collected observations with simulations produced using the ISBA and SVS surface models in summer and the Crocus snow model in winter. The comparison with surface models is particularly important as they are used with atmospheric models to generate weather forecasts and climate projections.In summer, we found that 23% of the net radiation was converted to latent heat flux at our site, 35% to sensible heat flux, and about 15% to ground heat flux. This contrasts with six FLUXNET sites across the Arctic, where most of the net radiation is used to drive the latent heat flux, even though they all have much lower annual precipitation than our study site. We attribute this behavior to the high hydraulic conductivity of the soil (presence of littoral and intertidal sediments), typical of the coastal regions of the eastern Canadian Arctic. The ISBA and SVS land surface models overestimate the surface water content of these soils, but are able to accurately simulate turbulent heat fluxes, including sensible heat flux and, to a lesser extent, latent heat flux.In winter, the snow cover completely changes the surface energy balance. Energy losses due to longwave radiation are largely offset by the sensible heat flux, while the latent heat flux is minimal. At the surface of the snow cover, the heat flux in the snow is similar in magnitude to the sensible heat flux. As the snow cover stores very little heat, the magnitude of the heat flux in the snow is comparable to the heat flux in the ground. Overall, Crocus is able to reproduce the observed energy balance, but shows some shortcomings when simulating turbulent heatfluxes at an hourly time step under stable atmospheric conditions.Since the two vegetation types in the FTE, tundra and forest, have a contrasting effect on the snow cover on the ground, we analyzed the snowpack properties at each of the two environments. Again, we used the Crocus snow model to simulate snow properties at both sites.First, our observations show that snow height and density differ significantly between the two sites. At the forest site, the snow is about twice as thick as at the tundra site, and the density decreases from the ground to the snow surface, while the opposite is observed at the tundrasite. Crocus is not able to reproduce these density profiles in its standard configuration. By adjusting the density settings for fresh snow, compaction in the presence of vegetation and blown snow, we are able to simulate profiles comparable to the observations. We hypothesize that water vapor transport is the dominant mechanism shaping the density profile at the tundra site, while a combination of compaction due to the overburden weight and water vapor transport is responsible for the density profile at the forest site. This process is not included in Crocus and the adjustments partially compensate for this and are to some extent site-specific, making it difficult to apply the modifications implemented here on a larger scale.