Permafrost thermal amelioration tests near Schefferville, Quebec

1976 ◽  
Vol 13 (12) ◽  
pp. 1694-1705 ◽  
Author(s):  
Frank H. Nicholson
Keyword(s):  
Snow Depth ◽  
Heat Losses ◽  
Mean Annual Temperature ◽  
Net Radiation ◽  
Natural Conditions ◽  
Plot Size ◽  
Summer Heat ◽  
Snow Fences ◽  
Test Result ◽  
Lateral Heat

Permafrost thermal amelioration techniques have been tested for 4 years near Schefferville (mean annual temperature −6 °C). The most important amelioration measure tested was the use of snow fences to increase snow depth and hence reduce winter heat losses, which affect the permafrost much more than changing the summer heat input conditions. However, when different summer treatments were tested, stripping the vegetation, darkening the ground and using thin transparent covers proved beneficial. Monitoring included deep ground temperature measurements (to 25 m), radiation instruments, lysimeters, and measurement of ground thermal properties. At 5 m depth, between 20 and 40 × 106 Jm−2 are gained and lost each year under natural conditions, whereas the amelioration gave a continuous gain of 20 × 106 Jm−2 per annum (nearly 2% of net radiation), increasing mean temperature by 2.5 °over 4 years. At the 10 m depth corresponding gains were 10 × 106 Jm−2 and 1.5°. The rocks (iron-rich) have high thermal conductivities, and slower amelioration results are likely in other areas. Limited plot size (7500 m2) has resulted in significant lateral heat loss. The overall test result is that the active layer has been greatly deepened but no thaw has yet been held through a full winter. The method would be useful in several mining applications, including the prevention of new permafrost.

scholarly journals Summer Heat and Ice Balances on Hodges Glacier, South Georgia, Falkland Islands Dependencies

1982 ◽  
Vol 28 (99) ◽  
pp. 221-238 ◽  
Author(s):  
I. G. G. Hogg ◽  
J. G. Paren ◽  
R. J. Timmis
Keyword(s):  
Latent Heat ◽  
Heat Balance ◽  
Significant Contribution ◽  
Heat Fluxes ◽  
Falkland Islands ◽  
Mountain Range ◽  
Ablation Zone ◽  
Net Radiation ◽  
Summer Heat ◽  
The Heat Balance

AbstractThe heat and ice balances of a temperate sub-Antarctic cirque glacier were measured through the 1973–74 melt season at an altitude midway between the climatic firn limit and the snout. The melt calculated from mean daily measurements at a single level of net radiation, wind-speed, temperature, and humidity agreed with that observed at nearby budget stakes. In the central ablation zone, radiation provided (54 ± 6)% and sensible fluxes (46 ± 6)% of the heat income through the summer, which was exceptionally warm and sunny. Latent-heat fluxes made no significant contribution to the heat balance. The calculation by Smith (1960) that the radiative, sensible, and latent heat fluxes contribute about equally to ablation in this zone has not been substantiated by measurement. The measured partition of the glacier’s heat balance suggested that maritime influences on its regime are mitigated by its position in the lee of a major mountain range.

Variation in canopy energy exchange characteristics across an ecosystem mosaic in the dry Mediterranean region

2020 ◽  
Author(s):  
Madi Amer ◽  
Rafael Stern ◽  
Eyal Rotenberg ◽  
Dan Yakir
Keyword(s):  
Mediterranean Region ◽  
Aridity Index ◽  
Heat Fluxes ◽  
Arid Ecosystems ◽  
Radiation Balance ◽  
Mean Annual Temperature ◽  
Canopy Conductance ◽  
Net Radiation ◽  
Radiative Balance ◽  
Semi Arid

<p>Assessment of the plant-climatic interactions in the land biosphere requires a combined perspective of both the biogeochemical effects (BGC; such as the carbon sink), and the biogeophysical effects (BGP; such as the vegetation albedo and radiative balance), which can often have contrasting consequences for ecosystem functioning and climate. Aiming to increase our knowledge on semi-arid ecosystems that are insufficiently represented in global studies, we examine the variations in key BGP features among different vegetation types in a dry Mediterranean region in southern Israel.</p><p>The study included planted pine forest (<em>pinus halepensis</em>), natural broad-leaf oak maquis (<em>Quercus calliprinos</em>), wheat field and a managed grassland, located in close proximity (within 2 km) under the same climatic conditions (mean annual temperature = 20.8C, annual mean precipitation, P= 403 mm, aridity index = 0.4). Using a state-of-the-art mobile laboratory, we carried out measurement campaigns of eddy covariance fluxes of CO2, sensible, H, and latent, LE, heat fluxes, and the radiation balance (incoming and outgoing short- and long-wave radiations) between the ecosystems and the atmosphere in different seasons during 2016-2018.</p><p>The results showed significant differences in net radiation and in albedo among the ecosystem, with net radiation values of ~666, ~582, ~443 and 456 W m<sup>-2 </sup>and albedo values of ~0.13, ~0.16, ~0.19 and ~0.20 for pines, maquis, wheat and grassland, respectively. The lowest albedo of the pine stand was associated with the largest H (a ‘convector effect’) of ~583 W m<sup>-2</sup> compared to ~313, ~198 and ~176 W m<sup>-2</sup> in the maquis, wheat and grassland ecosystems (midday means of peak activity season). The pine stand was also more adjusted to stress conditions than the oak maquis ecosystem through ‘avoidance’ of high activities during extreme conditions of heat and drought (reducing canopy conductance and associated fluxes). It is likely that the observed differences between the pine and oak maquis stand help explain the greater expansion of pine stands into the semi-arid regions, even to areas with mean annual P of 290 mm (aridity index = 0.2) where oak maquis cannot be found.</p>

scholarly journals Soil Moisture–Atmosphere Interactions during the 2003 European Summer Heat Wave

2007 ◽  
Vol 20 (20) ◽  
pp. 5081-5099 ◽  
Author(s):  
E. M. Fischer ◽  
S. I. Seneviratne ◽  
P. L. Vidale ◽  
D. Lüthi ◽  
C. Schär
Keyword(s):  
Soil Moisture ◽  
Heat Wave ◽  
Regional Climate ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Net Radiation ◽  
Temperature Anomalies ◽  
Continental Scale ◽  
Summer Heat

Abstract The role of land surface–related processes and feedbacks during the record-breaking 2003 European summer heat wave is explored with a regional climate model. All simulations are driven by lateral boundary conditions and sea surface temperatures from the ECMWF operational analysis and 40-yr ECMWF Re-Analysis (ERA-40), thereby prescribing the large-scale circulation. In particular, the contribution of soil moisture anomalies and their interactions with the atmosphere through latent and sensible heat fluxes is investigated. Sensitivity experiments are performed by perturbing spring soil moisture in order to determine its influence on the formation of the heat wave. A multiyear regional climate simulation for 1970–2000 using a fixed model setup is used as the reference period. A large precipitation deficit together with early vegetation green-up and strong positive radiative anomalies in the months preceding the extreme summer event contributed to an early and rapid loss of soil moisture, which exceeded the multiyear average by far. The exceptionally high temperature anomalies, most pronounced in June and August 2003, were initiated by persistent anticyclonic circulation anomalies that enabled a dominance of the local heat balance. In this experiment the hottest phase in early August is realistically simulated despite the absence of an anomaly in total surface net radiation. This indicates an important role of the partitioning of net radiation in latent and sensible heat fluxes, which is to a large extent controlled by soil moisture. The lack of soil moisture strongly reduced latent cooling and thereby amplified the surface temperature anomalies. The evaluation of the experiments with perturbed spring soil moisture shows that this quantity is an important parameter for the evolution of European heat waves. Simulations indicate that without soil moisture anomalies the summer heat anomalies could have been reduced by around 40% in some regions. Moreover, drought conditions are revealed to influence the tropospheric circulation by producing a surface heat low and enhanced ridging in the midtroposphere. This suggests a positive feedback mechanism between soil moisture, continental-scale circulation, and temperature.

scholarly journals EPIDEMIOLOGY OF BLACKHEAD IN TURKEYS UNDER APPROXIMATELY NATURAL CONDITIONS

1920 ◽  
Vol 31 (5) ◽  
pp. 633-646 ◽  
Author(s):  
Theobald Smith ◽  
H. W. Graybill
Keyword(s):  
Food Supply ◽  
Field Experiments ◽  
The Other ◽  
Mean Annual Temperature ◽  
Infectious Agents ◽  
View Point ◽  
Natural Conditions ◽  
Chicken Pox ◽  
Sources Of Infection ◽  
Ground Material

The foregoing experiments in outdoor, unprotected enclosures demonstrates the difficulties surrounding the rearing of turkeys. These are discussed from another view-point and to avoid repetition only a few outlying facts should be considered here. The occasional presence of coccidia, the presence of Heterakis papillosa in the ceca, the occurrence of cases of aspergillosis and of chicken-pox in incubator-bred birds which did not come in contact with other domesticated birds, except in a few cases with incubator-bred chickens, show clearly that turkeys are picking up from the ground material deposited by other birds. The agent of blackhead must come from the same sources. The field experiments show a steadily increasing concentration of the infection from 1917 to 1919, even though the ground had been ploughed and seeded before use. As a result, the various groups of turkeys became infected to a greater degree. The growth in the intensity of the disease may be in part ascribed to an accumulation on the soil of infectious agents during any given season after they had been introduced, but it is hardly acceptable as an explanation from season to season, when the soul was either virgin, as regards poultry yards, or ploughed deep and seeded before use. A more rational hypothesis is the gradual attraction of birds in larger numbers and greater variety on account of the food supply in the turkey enclosures and the more intensive cultivation of the land surrounding the laboratory and animal buildings since the beginning of the experiments in 1917. The intensity of the outbreaks due to the confining of young turkeys with birds over a year old which had been infected during the preceding year, or on ground previously occupied by them, was in all instances much greater than in the spontaneous outbreaks. The cases amounted to nearly 100 per cent of the exposed. On the other hand, the number of cases in the control flocks varied and was very low in some groups. It could have been kept down if the sick birds had been promptly removed and not permitted to recover on the same ground. However, the object of the experiment was not to suppress the disease, but to see to what extent it would develop. It is self-evident that the results obtained apply strictly only to that part of the country where the experiments were made. We have at present no means of knowing whether the sources of infection would become more numerous and concentrated with a higher mean annual temperature, or the reverse. Only by using incubator turkeys exclusively for such tests and eliminating the older turkeys and domesticated birds as carriers, can the miscellaneous, at present not controllable sources of the agents of this disease in different localities and the chances of successful rearing be determined.

Reconstruction of Annual Temperature (1590–1979) for Longmire, Washington, Derived from Tree Rings

1986 ◽  
Vol 25 (2) ◽  
pp. 223-234 ◽  
Author(s):  
Lisa J. Graumlich ◽  
Linda B. Brubaker
Keyword(s):  
20Th Century ◽  
Snow Depth ◽  
Response Surfaces ◽  
Cascade Range ◽  
Mean Annual Temperature ◽  
The Past ◽  
Larix Lyallii ◽  
Short Period ◽  
Negative Effect ◽  
Combine Information

Annual growth records from trees at timberline in the Cascade Range of Washington are correlated with variations in temperature and snow depth and used to reconstruct climatic variation in the past. Response surfaces indicate that growth of mountain hemlock (Tsuga mertensiana) and subalpine larch (Larix lyallii) is positively correlated with summer (July to September) temperature and negatively correlated with spring (March) snow depth when snow depth is at or below average. During years of above average snow depth, temperature has little effect on mountain hemlock but has a negative effect on growth in subalpine larch. These interactions make it difficult to reconstruct these climatic variables separately using standard methods. Mean annual temperature values, which combine information on both summer temperature and spring snow depth, were estimated from a regression model that reconstructs past temperature at Longmire, Washington, as a function of larch and hemlock tree-ring chronologies. The reconstruction of mean annual temperature shows temperatures between 1590 and 1900 to be approximately 1°C lower than those of the 20th century. Only during a short period from 1650 to 1690 did temperatures approach 20th-century values.

scholarly journals Summer Heat and Ice Balances on Hodges Glacier, South Georgia, Falkland Islands Dependencies

1982 ◽  
Vol 28 (99) ◽  
pp. 221-238 ◽  
Author(s):  
I. G. G. Hogg ◽  
J. G. Paren ◽  
R. J. Timmis
Keyword(s):  
Latent Heat ◽  
Heat Balance ◽  
Significant Contribution ◽  
Heat Fluxes ◽  
Falkland Islands ◽  
Mountain Range ◽  
Ablation Zone ◽  
Net Radiation ◽  
Summer Heat ◽  
The Heat Balance

AbstractThe heat and ice balances of a temperate sub-Antarctic cirque glacier were measured through the 1973–74 melt season at an altitude midway between the climatic firn limit and the snout. The melt calculated from mean daily measurements at a single level of net radiation, wind-speed, temperature, and humidity agreed with that observed at nearby budget stakes. In the central ablation zone, radiation provided (54 ± 6)% and sensible fluxes (46 ± 6)% of the heat income through the summer, which was exceptionally warm and sunny. Latent-heat fluxes made no significant contribution to the heat balance. The calculation by Smith (1960) that the radiative, sensible, and latent heat fluxes contribute about equally to ablation in this zone has not been substantiated by measurement. The measured partition of the glacier’s heat balance suggested that maritime influences on its regime are mitigated by its position in the lee of a major mountain range.

Seasonal and regional variations in coat characteristics of dairy cattle

1961 ◽  
Vol 12 (3) ◽  
pp. 528 ◽  
Author(s):  
A Berman ◽  
R Volcani
Keyword(s):  
Annual Cycle ◽  
Fibre Diameter ◽  
Day Length ◽  
Mean Annual Temperature ◽  
Maximum Weight ◽  
Jordan Valley ◽  
Natural Conditions ◽  
Climatic Regions ◽  
Hair Fibre ◽  
Hair Diameter

The annual cycle in coat growth and shedding rates was investigated in Holstein and Syrian x Holstein cattle (3.1-6.2% relationship to the Syrian) under natural conditions in three different climatic regions of Israel. Hair quantity, coat thickness, and hair diameter were tested monthly on an area of 100 cm2 on the thigh. 541 samples were taken during 1 year. Cows were tested in two herds in the Jordan Valley (mean annual temperature 23�C), one herd in the Coasral Plain (mean annual temperature 20.4�C), and one in the Jerusalem area (mean annual temperature 17.5�C). Hair quantity and coat thickness in the Jordan Valley were very- significantly smaller than in the other two regions. A clear cycle was observed in these three factors. Weight of hair reached the peak In January, then decreased to 50% of the maximum weight during April-Nay and increased again during May-June, reaching 75% of the maximum weight. From October hair growth continued, to the peak in January. Variations in coat thickness differed from those in weight of hair during summer, when coat thickness stayed lox and stable until autumn. Hair fibre diameter was lowest between December and March, then increased sharply until June. Hair quantity and coat thickness decreased more and faster in the Jordan Valley. These results show that day length is not the only factor influencing the annual cycle of hair quantity and coat thickness but that, apparently, the air temperature? are of influence too. In this experiment hair diameter was influenced only by variations in day length.

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