Freezing dehydration damages roots of containerized Scots pine (Pinussylvestris) seedlings overwintering under subarctic conditions

1996 ◽  
Vol 26 (9) ◽  
pp. 1602-1609 ◽  
Author(s):  
Marja-Liisa Sutinen ◽  
Kari Mäkitalo ◽  
Raimo Sutinen
Keyword(s):  
Snow Cover ◽  
Growth Medium ◽  
Scots Pine ◽  
Sugar Content ◽  
Snow Accumulation ◽  
Root Tissue ◽  
Subzero Temperature ◽  
Subarctic Region ◽  
Winter Conditions ◽  
Living Root

The survival of conifer roots under winter conditions is not well understood. The effect of long-lasting freezing at extremely low temperatures on the survival of the roots of Scots pine (Pinussylvestris L.) seedlings from a timberline seed source was studied. One-year-old containerized seedlings were kept for 4 months under winter conditions typical of the subarctic region. The freezing treatment was accelerated by preventing snow accumulation on half of the seedlings. The proportion of living root tissue and the amount of sugars (glucose, fructose, and sucrose) and starch in the needles and roots were measured at weekly intervals. The temperature within the growth medium without snow cover fell on a number of occasions to −30 °C. The lowest temperature recorded within the snow-covered growth medium was −20 °C. The sugar content increased faster and to a higher level in the seedlings without snow cover, but it did not affect root survival. The proportion of living root tissue without a cover of snow decreased by 80% by the end of December, and the roots were completely injured by the end of February. There was only a slight decrease in the proportion of living roots among seedlings covered by snow. The reduced root survival was not directly related to exposure to the lowest freezing temperatures; instead, it was manifested some weeks after exposure. This suggests that dehydration resulting from prolonged severe freezing caused root damage. The presence of a cover of snow reduces subzero temperature extremes and the severity of dehydration; together, these result in enhanced root survival.

Seasonal variations in the properties and structural composition of sea ice and snow cover in the Bellingshausen and Amundsen Seas, Antarctica

1997 ◽  
Vol 43 (143) ◽  
pp. 138-151 ◽  
Author(s):  
M. O. Jeffries ◽  
K. Morris ◽  
W.F. Weeks ◽  
A. P. Worby
Keyword(s):  
Sea Ice ◽  
Isotopic Composition ◽  
Snow Cover ◽  
Sea Water ◽  
Ice Cores ◽  
Ice Cover ◽  
Snow Accumulation ◽  
Ice Formation ◽  
Frazil Ice ◽  
Core Sets

AbstractSixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

Experiments on wind-driven heat exchange processes over melting snow

2021 ◽  
Author(s):  
Michael Haugeneder ◽  
Tobias Jonas ◽  
Dylan Reynolds ◽  
Michael Lehning ◽  
Rebecca Mott
Keyword(s):  
Snow Cover ◽  
Surface Wind ◽  
Infrared Camera ◽  
Snow Accumulation ◽  
Internal Boundary ◽  
Small Scale ◽  
Snow Melt ◽  
Two Dimensional ◽  
Atmospheric Conditions ◽  
Near Surface

<p>Snowmelt runoff predictions in alpine catchments are challenging because of the high spatial variability of t<span>he snow cover driven by </span>various snow accumulation and ablation processes. In spring, the coexistence of bare and snow-covered ground engages a number of processes such as the enhanced lateral advection of heat over partial snow cover, the development of internal boundary layers, and atmospheric decoupling effects due to increasing stability at the snow cover. The interdependency of atmospheric conditions, topographic settings and snow coverage remains a challenge to accurately account for these processes in snow melt models.<br>In this experimental study, we used an Infrared Camera (VarioCam) pointing at thin synthetic projection screens with negligible heat capacity. Using the surface temperature of the screen as a proxy for the air temperature, we obtained a two-dimensional instantaneous measurement. Screens were installed across the transition between snow-free and snow-covered areas. With IR-measurements taken at 10Hz, we capture<span> the dynamics of turbulent temperature fluctuations</span><span> </span>over the patchy snow cover at high spatial and temporal resolution. From this data we were able to obtain high-frequency, two-dimensional windfield estimations adjacent to the surface.</p><p>Preliminary results show the formation of a stable internal boundary layer (SIBL), which was temporally highly variable. Our data suggest that the SIBL height is very shallow and strongly sensitive to the mean near-surface wind speed. Only strong gusts were capable of penetrating through this SIBL leading to an enhanced energy input to the snow surface.</p><p>With these type of results from our experiments and further measurements this spring we aim to better understand small scale energy transfer processes over patch snow cover and it’s dependency on the atmospheric conditions, enabling to improve parameterizations of these processes in coarser-resolution snow melt models.</p>

scholarly journals An outline of avalanches in the Tien Shan mountains

1992 ◽  
Vol 16 ◽  
pp. 7-10 ◽  
Author(s):  
Hu Ruji ◽  
Ma Hong ◽  
Wang Guo
Keyword(s):  
Snow Cover ◽  
Basal Layer ◽  
Liquid Water Content ◽  
Snow Accumulation ◽  
Tien Shan ◽  
Large Temperature ◽  
Snow Avalanches ◽  
Climatic Variations ◽  
Tien Shan Mountains ◽  
Seasonal Snow Cover

The seasonal snow cover in the Tien Shan mountains is characterized by low density, low liquid-water content and low temperature. It is known as typical dry snow. Large temperature gradients in the basal layer of the snow cover exist throughout the entire period of snow accumulation, and depth hoar is therefore extremely well-developed. Full-depth depth-hoar avalanches, however, seldom occur. Avalanches in the Tien Shan mountains are mostly loose snow avalanches. Although normally not large in size, they are the most dangerous type. The occurrence of hazardous avalanches shows cycles of about ten years because of periodic climatic variations.

scholarly journals Precipitation and snow cover in the Himalaya: from reanalysis to regional climate simulations

2013 ◽  
Vol 17 (10) ◽  
pp. 3921-3936 ◽  
Author(s):  
M. Ménégoz ◽  
H. Gallée ◽  
H. W. Jacobi
Keyword(s):  
Snow Cover ◽  
Climate Model ◽  
Regional Climate ◽  
Rain Gauge ◽  
Snow Accumulation ◽  
The Tibetan Plateau ◽  
Monsoon Period ◽  
Medium Range Weather Forecast ◽  
Snow Cover Extent ◽  
The Himalaya

Abstract. We applied a Regional Climate Model (RCM) to simulate precipitation and snow cover over the Himalaya, between March 2000 and December 2002. Due to its higher resolution, our model simulates a more realistic spatial variability of wind and precipitation than those of the reanalysis of the European Centre of Medium range Weather Forecast (ECMWF) used as lateral boundaries. In this region, we found very large discrepancies between the estimations of precipitation provided by reanalysis, rain gauges networks, satellite observations, and our RCM simulation. Our model clearly underestimates precipitation at the foothills of the Himalaya and in its eastern part. However, our simulation provides a first estimation of liquid and solid precipitation in high altitude areas, where satellite and rain gauge networks are not very reliable. During the two years of simulation, our model resembles the snow cover extent and duration quite accurately in these areas. Both snow accumulation and snow cover duration differ widely along the Himalaya: snowfall can occur during the whole year in western Himalaya, due to both summer monsoon and mid-latitude low pressure systems bringing moisture into this region. In Central Himalaya and on the Tibetan Plateau, a much more marked dry season occurs from October to March. Snow cover does not have a pronounced seasonal cycle in these regions, since it depends both on the quite variable duration of the monsoon and on the rare but possible occurrence of snowfall during the extra-monsoon period.

scholarly journals Modeling Snow Depth and Snow Water Equivalent Distribution and Variation Characteristics in the Irtysh River Basin, China

2021 ◽  
Vol 11 (18) ◽  
pp. 8365
Author(s):  
Liming Gao ◽  
Lele Zhang ◽  
Yongping Shen ◽  
Yaonan Zhang ◽  
Minghao Ai ◽  
...  
Keyword(s):  
Snow Cover ◽  
River Basin ◽  
Snow Depth ◽  
Snow Water Equivalent ◽  
Snow Accumulation ◽  
Implicit Scheme ◽  
Snow Water ◽  
Irtysh River ◽  
Simulation Results ◽  
The Irtysh River

Accurate simulation of snow cover process is of great significance to the study of climate change and the water cycle. In our study, the China Meteorological Forcing Dataset (CMFD) and ERA-Interim were used as driving data to simulate the dynamic changes in snow depth and snow water equivalent (SWE) in the Irtysh River Basin from 2000 to 2018 using the Noah-MP land surface model, and the simulation results were compared with the gridded dataset of snow depth at Chinese meteorological stations (GDSD), the long-term series of daily snow depth dataset in China (LSD), and China’s daily snow depth and snow water equivalent products (CSS). Before the simulation, we compared the combinations of four parameterizations schemes of Noah-MP model at the Kuwei site. The results show that the rainfall and snowfall (SNF) scheme mainly affects the snow accumulation process, while the surface layer drag coefficient (SFC), snow/soil temperature time (STC), and snow surface albedo (ALB) schemes mainly affect the melting process. The effect of STC on the simulation results was much higher than the other three schemes; when STC uses a fully implicit scheme, the error of simulated snow depth and snow water equivalent is much greater than that of a semi-implicit scheme. At the basin scale, the accuracy of snow depth modeled by using CMFD and ERA-Interim is higher than LSD and CSS snow depth based on microwave remote sensing. In years with high snow cover, LSD and CSS snow depth data are seriously underestimated. According to the results of model simulation, it is concluded that the snow depth and snow water equivalent in the north of the basin are higher than those in the south. The average snow depth, snow water equivalent, snow days, and the start time of snow accumulation (STSA) in the basin did not change significantly during the study period, but the end time of snow melting was significantly advanced.

scholarly journals Two years with extreme and little snowfall: effects on energy partitioning and surface energy exchange in a high-Arctic tundra ecosystem

2016 ◽  
Vol 10 (4) ◽  
pp. 1395-1413 ◽  
Author(s):  
Christian Stiegler ◽  
Magnus Lund ◽  
Torben Røjle Christensen ◽  
Mikhail Mastepanov ◽  
Anders Lindroth
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Snow Cover ◽  
Energy Exchange ◽  
Surface Energy Balance ◽  
Arctic Tundra ◽  
High Arctic ◽  
Snow Accumulation ◽  
Heat Fluxes ◽  
Tundra Ecosystem

Abstract. Snow cover is one of the key factors controlling Arctic ecosystem functioning and productivity. In this study we assess the impact of strong variability in snow accumulation during 2 subsequent years (2013–2014) on the land–atmosphere interactions and surface energy exchange in two high-Arctic tundra ecosystems (wet fen and dry heath) in Zackenberg, Northeast Greenland. We observed that record-low snow cover during the winter 2012/2013 resulted in a strong response of the heath ecosystem towards low evaporative capacity and substantial surface heat loss by sensible heat fluxes (H) during the subsequent snowmelt period and growing season. Above-average snow accumulation during the winter 2013/2014 promoted summertime ground heat fluxes (G) and latent heat fluxes (LE) at the cost of H. At the fen ecosystem a more muted response of LE, H and G was observed in response to the variability in snow accumulation. Overall, the differences in flux partitioning and in the length of the snowmelt periods and growing seasons during the 2 years had a strong impact on the total accumulation of the surface energy balance components. We suggest that in a changing climate with higher temperature and more precipitation the surface energy balance of this high-Arctic tundra ecosystem may experience a further increase in the variability of energy accumulation, partitioning and redistribution.

The Effect of Climate Change on River Flow and Snow Cover in the NOPEX Area Simulated by a Simple Water Balance Model

1997 ◽  
Vol 28 (4-5) ◽  
pp. 273-282 ◽  
Author(s):  
C-Y Xu ◽  
Sven Halldin
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Snow Cover ◽  
Annual Runoff ◽  
Snow Accumulation ◽  
Water Balance Model ◽  
Annual Precipitation ◽  
Balance Model ◽  
Climate Change Scenarios ◽  
Average Annual Runoff

Within the next few decades, changes in global temperature and precipitation patterns may appear, especially at high latitudes. A simple monthly water-balance model of the NOPEX basins was developed and used for the purposes of investigating the effects on water availability of changes in climate. Eleven case study catchments were used together with a number of climate change scenarios. The effects of climate change on average annual runoff depended on the ratio of average annual runoff to average annual precipitation, with the greatest sensitivity in the catchments with lowest runoff coefficients. A 20% increase in annual precipitation resulted in an increase in annual runoff ranging from 31% to 51%. The greatest changes in monthly runoff were in winter (from December to March) whereas the smallest changes were found in summer. The time of the highest spring flow changed from April to March. An increase in temperature by 4°C greatly shortened the time of snow cover and the snow accumulation period. The maximum amount of snow during these short winters diminished by 50% for the NOPEX area even with an assumed increase of total precipitation by 20%.

scholarly journals Graphene Oxide-Assisted Promotion of Plant Growth and Stability

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 758 ◽  
Author(s):  
Sunho Park ◽  
Kyoung Soon Choi ◽  
Sujin Kim ◽  
Yonghyun Gwon ◽  
Jangho Kim
Keyword(s):  
Arabidopsis Thaliana ◽  
Graphene Oxide ◽  
Plant Growth ◽  
Growth Medium ◽  
Fruit Ripening ◽  
Sugar Content ◽  
Flower Buds ◽  
Ripening Process ◽  
Number Of Leaves ◽  
Positive Effect

The control and promotion of plant and crop growth are important challenges globally. In this study, we have developed a nanomaterial-assisted bionic strategy for accelerating plant growth. Although nanomaterials have been shown to be toxic to plants, we demonstrate herein that graphene oxide can be used as a regulator tool for enhancing plant growth and stability. Graphene oxide was added to the growth medium of Arabidopsis thaliana L. as well as injected into the stem of the watermelon plant. We showed that with an appropriate amount provided, graphene oxide had a positive effect on plant growth in terms of increasing the length of roots, the area of leaves, the number of leaves, and the formation of flower buds. In addition, graphene oxide affected the watermelon ripeness, increasing the perimeter and sugar content of the fruit. We believe that graphene oxide may be used as a strategy for enabling the acceleration of both plant growth and the fruit ripening process.

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