Hydro-climatic drivers of mid-winter break-up of river ice in western Canada and Alaska

2016 ◽  
Vol 48 (4) ◽  
pp. 945-956 ◽  
Author(s):  
B. W. Newton ◽  
T. D. Prowse ◽  
L. P. de Rham

The mid-winter break-up of a competent river ice cover can cause ice jamming and flooding, which can have profound impacts on the structure and strength of the ice cover. This research identifies 52 mid-winter break-up events in western Canada (1950–2008) and Alaska (1950–2014) and evaluates the hydro-climatic drivers including temperature and precipitation. The identified mid-winter break-up events are primarily located in the temperate zone, defined as the region between 400 and 1,000 winter (December–February) freezing degree-days. Further delineation by terrestrial biome revealed considerable variability in hydro-climatic triggers, particularly the role of freeze-thaw days (Tmax > 0 °C and Tmin < 0 °C) in Tundra and Boreal Forest/Taiga biomes and short-term (3-day) warming events in Temperate Coniferous Forests and Temperate Grasslands, Savannas, and Shrublands. The classification of 5-day sequences of mid-tropospheric circulation indicates that a persistent trough of low-pressure over Alaska and the North Pacific is the dominant pattern preceding mid-winter break-ups. Furthermore, the trough is stronger for events in British Columbia and Alberta compared with Alaska and the Yukon. The results of this research improve our understanding of the hydro-climatic conditions that generate mid-winter break-up events in western Canada and Alaska and will aid in the prediction and risk management of such events.

2021 ◽  
Vol 36 ◽  
pp. 01003
Author(s):  
Elena Vologzhanina ◽  
Galina Batalova

The results of the study of 12 varieties and promising lines of glumaceous oat in the competitive variety testing of the FASC of the North-East (Kirov region) in the period from 2018 to 2020 are presented. The purpose of the research is to assess the productivity, ecological plasticity and stability of the genotypes of glumaceous oat for feed and universal use in the conditions of the Volga-Vyatka region. The dependences of grain yield and dry matter harvesting on the state of agro-climatic resources (HTC), temperature and precipitation are established. The contrasting weather conditions during the years of research allowed to conduct the most complete assessment of the studied genotypes. The most favorable conditions for the formation of a high yield of green mass of oat were formed in 2020 (Ij=3.76), grain - in 2019 (Ij=1.35). The average degree of positive dependence of green mass yield on the height of oat plants was revealed (r=0.51). The variety of the high-intensity type of the universal direction Medved, promising lines of the mowing direction (178h13 and 245h14) are distinguished.


2020 ◽  
Vol 6 (2) ◽  
pp. 42-46
Author(s):  
M. Mammadova

The Zayamchay basin is selected by its complex structure, various climatic conditions, rich vegetation and soil–rich rocks. This variation of soil–forming factors has led to the formation of various forms of soil cover structure within the basin. Therefore, the study of land and its space manifestation — the soil cover structure, detail mapping, evaluation and optimization — both scientifically–theoretical and practical. The Zeyamchay basin, which is located on the north–western slope of the Lesser Caucasus, is the object of the research. The Zeyamchay basin is selected by its complex relief structure, various climatic conditions, rich vegetation and soil–rich rocks. The area of the basin is 94200 hectares. The basin covers part of Tovuz, Shamkir and Gadabay districts from the administrative point of view. These kind of soil–forming factors have led to the formation of different forms of soil cover structure within the basin. During the research, empirical information is collected from cartographic, soil research, aerospace, landscape and geomorphological methods and so on was used.


Author(s):  
Karen Radner ◽  
Nadine Moeller ◽  
D. T. Potts

With the emphasis of the Oxford History of the Ancient Near East firmly placed on the political, social, and cultural histories of the states and communities shaping Egypt and Western Asia (including the Levant, Anatolia, Mesopotamia, and Iran), this introduction to the five-volume series seeks to place the region in its environmental context. It discusses the lay of the land between the North African coast and the Hindu Kush, including the role of tectonics and geomorphology. It also considers some key issues regarding climatic conditions, focusing in particular on the significance of the Inter-Tropical Convergence Zone and the potential impact of megadroughts and pandemics.


2016 ◽  
Vol 77 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Anna Cedro

AbstractThe wild service tree (Sorbus torminalis L.) is a very rare tree species in Poland, where it reaches the north-eastern border of its natural range. The majority of this species’ stands is found in Wielkopolska. This study was aimed at examining the relationships between the growth and climate for trees of the species Sorbus torminalis L. growing in the Wielkopolska National Park and the Pniewy forest district (Wielkopolska). The samples for the analysis were taken from 63 trees. However, taking into account the missing growth rings and the difficult identification of the tree ring borders in sapwood, only ca. 30% of the samples could be synchronised and dated accurately. Applying the classic methods of dendrochronological dating, a 94- year STW chronology was constructed, spanning the years of 1920-2013. The chronology, in turn, was used as a basis for dendroclimatological analyses, including correlation, response function, and pointer years. The climatic data used in the analyses came from the meteorological station in Poznań; providing air temperature and precipitation for a period of 66 years (1948-2013) and 48 years of insolation data (1966-2013). Insolation had the highest negative impact and precipitation had the highest positive impact on the annual growth in May and June. Positive pointer years could be linked to humid months with low insolation during the growing season, while negative pointer years are characterised by deficient precipitation, a large number of sunny hours, and high air temperatures in the summer months.


2015 ◽  
Vol 42 (9) ◽  
pp. 645-655 ◽  
Author(s):  
Martin Jasek ◽  
Amy Pryse-Phillips

The objectives of the study were to describe the existing ice conditions in the Peace River and to predict changes as a result of the proposed Site C Clean Energy Project (the Project). The analyses of changes due to the Project were conducted using the CRISSP and PRTIGM models. Sixteen winters were simulated to provide a representative range of meteorological conditions on which to base the conclusions of the study. Potential changes are described in terms of the following ice characteristics: maximum upstream extent of ice cover; timing of ice cover formation and break-up; freeze-up and break-up water levels at the Town of Peace River; ice thickness; changes in ice conditions relevant for river ice crossings. The analyses also included predicting changes in these ice characteristics due to the combined influence of the Project and the proposed Dunvegan Hydro Project in Alberta. Two future climate scenarios were also considered.


2004 ◽  
Vol 35 (4-5) ◽  
pp. 281-293 ◽  
Author(s):  
Terry D. Prowse ◽  
Barrie R. Bonsal

Over most northern regions, break-up is primarily a spring event. Historical evidence, however, has shown that the timing of river-ice break-up has been shifting in many areas of the Northern Hemisphere and these shifts were associated with observed air temperatures during the break-up period. This paper reviews past trends in break-up from the Eurasian and North American circumpolar regions and synthesizes them into a regional and temporal context. It also evaluates various hydro-climatic explanations for these trends including associations with winter/spring air temperature variations and relationships to large-scale circulation patterns. Even more dramatic changes to break-up timing and magnitude are forecast to occur as the result of climate change. Insights toward future break-up conditions are discussed for two broad-scale regions: the North, a region forecast to experience the most pronounced warming, and the southern limit of the cold regions, a zone of particular cryospheric sensitivity to warming.


Author(s):  
Attila J. Trájer

AbstractFormer studies proposed that the speciation of the subgenus Paraphlebotomus happened in the Neogene Epoch in the circum-Mediterranean region due to the geographical segregation effect of the former Paratethys Sea. It was aimed to study whether the modelled Neogene ranges of Phlebotomus sergenti and Phlebotomus similis support or contradict this barrier role of the Paratethys in the speciation of Paraphlebotomus sandfly. For this purpose, the potential Neogene geographical ranges of Phlebotomus sergenti and Phlebotomus similis were modelled based on the present climatic requirements of the taxa. The Miocene models do not support the circum-Paratethyan migration of the ancestor of Phlebotomus similis. In general, Phlebotomus similis shows a low affinity to the North Paratethyan shorelines during the entire Miocene epoch. The only exceptions are the Tortonian and early Messinian periods when the climatic conditions could be suitable for Phlebotomus similis in the North Paratethyan shorelines. It was found that neither the modelled late Miocene, Pliocene nor the mid-Pleistocene period distributions of Phlebotomus sergenti and Phlebotomus similis shows notable differences in the suitability values in the Balkans and the Middle East. It is most plausible that the divergence of the Phlebotomus similis and its relatives was related to the tectonic subsidence of the Hellene Orogenic Belt and Phlebotomus similis specialised in the Balkan Peninsula and the present-day North Pontic area during the middle-late Miocene epoch. The Messinian desiccations of the Mediterranean Basin and the Zanclean re-flood caused the migration, but not the speciation of Phlebotomus similis and its sister taxa.


1979 ◽  
Vol 1979 (1) ◽  
pp. 387-396 ◽  
Author(s):  
Gee Tsang

ABSTRACT Laboratory study showed that oil spilled under river ice cover could be recovered from a slot cut on the ice cover if the slot was properly dimensioned and the river flow and oil properties met certain criteria. The parameters affecting the containment and recovery capability of a slot were identified and their quantitative effects were studied through systematic experiments. Design curves were derived for proper design of slots normal to the flow. The study revealed that slots at an angle to the flow were more effective in trapping the spilled oil. In addition, they guided the oil to the more desirable points for recovery. Design curves for angled slot diverters were also obtained. In addition to slots, imbedded barriers and slot-barrier combinations were also studied for their effectiveness in containing and diverting spilled oil. The quantitative effects of the affecting parameters were studied through experiments and design curves were obtained for proper design of barriers and slot-barrier combinations. The laboratory study was used to guide a successful field exercise in March 1978 on the North Saskatchewan River in Alberta. In the field exercise, more than 99 percent of the oil spilled upstream was recovered by the slot. The field results and the laboratory predictions are compared.


2021 ◽  
Author(s):  
Marina Fonti ◽  
Olga Churakova (Sidorova) ◽  
Ivan Tychkov

<p>Air temperature increase and change in precipitation regime have a significant impact on northern forests leading to the ambiguous consequences due to the complex interaction between the ecosystem plant components and permafrost. One of the major interests in such circumstances is to understand how tree growth of the main forest species of the Siberian North will change under altering climatic conditions. In this work, we applied the process-based Vaganov-Shashkin model (VS - model) of tree growth in order to estimate the daily impact of climatic conditions on tree-ring width of larch trees in northeastern Yakutia (Larix cajanderi Mayr.) and eastern Taimyr (Larix gmelinii Rupr. (Rupr.) for the period 1956-2003, and to determine the extent to which the interaction of climatic factors (temperature and precipitation) is reflected in the tree-ring anatomical structure. Despite the location of the study sites in the harsh conditions of the north, and temperature as the main limiting factor, it was possible to identify a period during the growing season when tree growth was limited by lack of soil moisture. The application of the VS-model for the studied regions allowed establishing in which period of the growing season the water stress is most often manifest itself, and how phenological phases (beginning, cessation, and duration of larch growth) vary among the years.</p><p>The research was funded by RFBR, Krasnoyarsk Territory and Krasnoyarsk Regional Fund of Science, project number 20-44-240001 and by the Russian Ministry of Science and Higher Education (projects FSRZ-2020-0010).</p>


Sign in / Sign up

Export Citation Format

Share Document