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Jeffrey?D.?MirochaEmail author Branko?Kosovi? Judith?A.?Curry 《Boundary-Layer Meteorology》2005,117(1):37-71
A diagnostic study of heat transfer within the lower atmosphere and between the atmosphere and the surface of the Arctic Ocean
snow/ice pack during clear-sky conditions is conducted using data from the Surface Heat Budget of the Arctic Ocean (SHEBA)
field experiment. Surface heat budgets computed for four cloudy and four clear periods show that, while the net turbulent
heat fluxes at the surface are small during the cloudy periods, during the clear-sky periods they are a considerable source
of surface heating, balancing significant portions of the conductive heat fluxes from within the snow/ice pack. Analysis of
the dynamics and thermodynamics of the lower atmosphere during the clear-sky periods reveals that a considerable portion of
the heat lost to the surface by turbulent heat fluxes is balanced by locally strong heating near the atmospheric boundary-layer
(ABL) top due to the interaction of subsiding motions with the strong overlying temperature inversions surmounting the ABL.
This heat is then entrained into the ABL and transported to the surface by turbulent mixing, maintained by a combination of
vertical wind shear and wave-turbulence interactions. The frequency of stable, clear-sky periods, particularly during the
winter, combined with these results, suggests that the downward transfer of heat through the lower atmosphere and into the
surface represents an important component of the heat budgets of the lower atmosphere and snow/ice pack over the annual cycle 相似文献
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Abstract. The relative palatability of 13 algae common in the kelp beds of the west coast of the Cape Peninsula, South Africa, is experimentally investigated with respect to feeding by the sea urchin Parechinus angulosus.
We investigated 2 hypotheses: 1) that this important herbivore would feed selectively on these algae and 2) that Desmarestia firma, one of these algae, would be unattractive to Parechinus on account of the H2 S04 in the thallus.
Algal preferences are determined from 3 types of feeding experiment, results of which support our first hypothesis, and allow us to group the algae into 3 arbitrary categories: "preferred", "intermediate", and "non-preferred". To explain these patterns, we measured "relative astringen-cy" of each species (essentially a phenol measurement), and phenol content of 4 species (FOUN-DENIS method). Rates of feeding on single species are negatively correlated with relative astringen-cies (r = 0.76, P = 0.99). The high relative astringency of D. firma is caused by its high (18 % per dry mass) H2 S04 content, and it is non-preferred. Our results therefore support our second hypothesis. Other implications of these results are discussed. 相似文献
We investigated 2 hypotheses: 1) that this important herbivore would feed selectively on these algae and 2) that Desmarestia firma, one of these algae, would be unattractive to Parechinus on account of the H
Algal preferences are determined from 3 types of feeding experiment, results of which support our first hypothesis, and allow us to group the algae into 3 arbitrary categories: "preferred", "intermediate", and "non-preferred". To explain these patterns, we measured "relative astringen-cy" of each species (essentially a phenol measurement), and phenol content of 4 species (FOUN-DENIS method). Rates of feeding on single species are negatively correlated with relative astringen-cies (r = 0.76, P = 0.99). The high relative astringency of D. firma is caused by its high (18 % per dry mass) H
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Smiljana Đukičin Vučković Jasmina Đorđević Jelena Milanković Jovanov Branko Protić Tijana Đorđević 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2018,118(1):101-113
In the last decades, the development of transport infrastructure has been necessary because of the population increase and expansion of urban centres. Infrastructure development leads to modification and changes in areas characterized by high human population density. The lack of adequate transport infrastructure inhibits local economic and social performance. In the period of economic stability (from 1970 to 1990), important roads that increased the connectedness of the Kolubara District (Western Serbia) with other parts of the country and the surrounding countries were built, but there is still a need for the construction of new roads. In order to examine the attitude of the local population in regard to transport infrastructure, a survey was conducted using a questionnaire consisting of closed questions. This topic is one that has not previously been examined. The data obtained were analyzed statistically and showed that local people have a positive attitude towards the existing infrastructure and towards the construction of new roads. There are statistically significant differences between the attitudes of the local population in different municipalities. The results from this research offer an opportunity to develop guidelines which can influence traffic development in these and similar areas. 相似文献
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The structure-function parametersC
T
2
andC
v
2
of temperature and velocity, respectively, from the 1973 Minnesota experiments and from large-eddy and direct numerical simulations show a smooth transition from M–O similarity to the local scaling hypothesized by Nieuwstadt for the outer regions of the stable boundary layer. Under that hypothesis, turbulence statistics aloft depend on the local vertical fluxes of momentum and temperature, so these results suggest that remote-sensing measurements ofC
T
2
andC
v
2
could be used to infer vertical profiles of those fluxes. We argue that the sensitivity of the fluxes to unsteadiness, baroclinity, terrain slope, and breaking gravity waves precludes the universality of the vertical profiles of structure-function parameters in the stable PBL. We find that theC
T
2
profile is particularly sensitive to these effects, which is consistent with observations that it varies considerably from case to case. 相似文献
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