Decrease In Winter Temperature Research Articles

HABITATION CONDITIONS OF THE CAVE LION IN THE MIDDLE INDIGIRKA RIVER BASIN, NORTH-EAST SIBERIA, DURING THE MIDDLE AND LATE PLENIGLACIAL: RECONSTRUCTION BASED ON PALYNOLOGICAL DATA

Pollen analyses of the sediment from skulls cavities of two cave lions Panthera spelaea from the middle Indigirka River basin, North-East Siberia, were performed to reconstruct the habitat conditions of the animals and to estimate changes in vegetation and climatic conditions in the region. Composition of the pollen and non-pollen palynomorphs indicates that the predators most likely died on the river floodplain or near the shore of the thermokarst lake, where grass/sedge meadows and shrub thickets, providing rich grazing grounds for large herbivores, existed. Palynological data indicate that both in the early Middle Pleniglacial and in the LGM the regional vegetation included forest, shrub tundra, meadow, mire and steppe communities similar to modern cold steppes in central Yakutia. During early Marine Isotope Stage (MIS) 3, the participation of arboreal vegetation was greater than in the Last Glacial Maximum (LGM) due to higher summer temperatures. In MIS 2, the role of open herbaceous cryoxerotic communities was greater, which is associated with a higher continentality of climate and a decrease in winter temperatures. This reconstruction is consistent with the general sequence of landscape and climatic changes in the Arctic and Subarctic regions of Siberia in the Middle and Late Pleniglacial, based on paleobotanical studies of the locations of mammoth fauna and multidisciplinary studies of the Late Pleniglacial sediments from a broader area.

Interannual variation of the Warm Arctic–Cold Eurasia pattern modulated by Ural blocking and the North Atlantic Oscillation under changing sea ice conditions

Together with rapid Arctic warming and sea ice decline, especially over the Barents–Kara seas (BKS), extreme cold winters have occurred frequently in mid-latitudes, particularly in Central Eurasia. A pattern with two distinct winter temperature anomalies centered over the BKS and Central Eurasia is known as the Warm Arctic–Cold Eurasia (WACE) pattern. The impacts of sea ice loss over the BKS and internal atmospheric variability on past WACE formation remain under discussion mainly due to the large internal atmospheric variability in the mid-latitudes. This study analyzed a large-ensemble historical experiment prescribing observed sea ice condition to investigate the role of internal atmospheric variability in the observed interannual variation of the WACE pattern. Comparison of ensemble members suggests that internal atmospheric variability is important for regulating the magnitude of the WACE pattern. Besides the strong effect of local sea ice loss, winter temperature over the BKS increases due to warm advection driven by the Ural blocking and positive phase of the North Atlantic Oscillation. A decrease in winter temperature over Central Eurasia is mainly attributable to the cold advection enhanced by Ural blocking rather than the remote effect of sea ice decline over the BKS. Our study reveals the importance of internal atmospheric variability in elucidating the observed interannual variation of the WACE pattern.

Potential winter-season bias of annual temperature variations in monsoonal Tibetan Plateau since the last deglaciation

Knowledge of paleotemperature variation in the Tibetan Plateau (TP) can provide potential insights to evaluate the future climate change under ongoing global warming and to improve our understanding of the controversial Holocene temperature changes between stacked proxy and model simulation. Here, we present a 115-yr-resolution record of bGDGTs (branched glycerol dialkyl glycerol tetraethers) based mean annual air temperature (MAAT) from Ngamring Co in the southern TP, spanning the past 18 ka. Our record reveals the MAAT generally responds to annual insolation and greenhouse gases changes, showing slight cooling during the deglaciation and remaining at low temperature until 6 ka BP, and then warming up to present. Combination with other records reveals the regional annual temperature shows a warming trend in the Holocene, which is in agreement with the model simulation rather than the stacked proxies. Importantly, the distinct cold interval during 10–6 ka BP is not present either in the simulation or in most of records for the adjacent region. We suggest such cold interval was a response to the positive North Atlantic Oscillation (NAO) conditions during the early Holocene, which led to a decrease in winter temperature and increased snowfall in the southern TP. Considering the consistent pattern of local annual and winter insolation over past 18 ka, and the high correlation between annual and winter temperature over the past 40 yr, we cautiously indicate that winter season may be crucial for the annual temperature in the TP. Additional quantitative records with clear seasonal signals, especially in winter, are needed to confirm our hypothesis.

Asian monsoon and vegetation shift: evidence from the Siwalik succession of India

AbstractQuantitative Miocene climate and vegetation data from the Siwalik succession of western Nepal indicate that the development of the Indian summer monsoon has had an impact, though in part, on vegetation changes. The climate and vegetation of the Lower (middle Miocene) and Middle (late Miocene–Pliocene) Siwalik successions of Darjeeling, eastern Himalaya, have been quantified. Reconstructed climate data, using the Coexistence Approach, suggest a decrease in winter temperatures and precipitation during the wettest months (MPwet) from the Lower to Middle Siwalik. The floristic assemblage suggests that Lower Siwalik forests were dominated by wet evergreen taxa, whereas deciduous ones became more dominant during the Middle Siwalik. The vegetation shift in the eastern Himalayan Siwalik was most likely due to a decrease in MPwet. The quantified climate–vegetation data from the eastern and western Himalayan Siwalik indicate that changes in the Indian summer monsoon had a profound impact on vegetation development during the period of deposition. We suggest that the decrease in winter temperature and summer monsoon rainfall during the Middle Siwalik might be linked with the Northern Hemisphere glaciation/cooling or a number of other things that were also going on at the time, including the continued rise of the Himalaya, and drying across the Tibetan region, which may have affected atmospheric circulation regionally.

Variability in observed snow depth over China from 1960 to 2014

AbstractSnow depth is a critical variable that reflects snow variability and has an important impact on the energy and hydrological cycles. However, snow depth changes in response to regional climate warming have not been quantified in detail across China. Here, we investigated the variability in observed snow depth based on a recently released dataset collected at ~1,500 stations from 1960 to 2014. To address the non‐normal distribution of daily snow depth data, the annual cumulative amount of snow depth (CASD) is employed, and the trend is calculated and tested for the change point and field significance. The results showed that CASD experienced a slight increase of 1.75%·decade−1in China. An increasing trend of CASD was observed in Northeastern and Northwestern China, a decreasing trend was observed in the eastern Tibetan Plateau, Loess Plateau, and Yangtze River Basin, and these changes were more remarkable after the 2000s. Since the 2000s, the increased CASD in Northwestern and Northeastern China has been accompanied by a significant decrease in winter temperature and a sharply increasing trend in snowfall events in the northeastern region. The decreased CASD in the Eastern Tibetan Plateau and Loess Plateau after the 2000s was accompanied by a decrease in snowfall events and an increase in winter temperature. Large‐scale atmospheric circulation, such as the Arctic Oscillation (AO), has a remarkable regional effect on the variability in snow depth. Statistically significant negative correlations were found in the northern part of China (i.e., positive AO phase with reduced CASD), while significant positive correlations were shown in the middle part of China (i.e., positive AO phase with enhanced CASD). Furthermore, China experienced an obviously shorter snow season during the whole period (decreased by 3.87%·decade−1), jointly resulting from later starting dates and earlier ending dates.

On the issue of ensuring a safe service life of high-risk objects of railway equipment in natural climatic conditions of Siberian, Northern and Arctic regions

More than half of the territory of Russia, according to climatic maps, is referred to arctic and subarctic belts and areas of a sharply continental climate with the decrease in winter temperatures up to -60 °С and lower. Such conditions worsen physical and mechanical properties of metals and soil and lead to a decrease in main performance indicators. For example, at an ambient temperature below -30 °C, the impact strength, cold and crack propagation resistance of steel noticeably decrease, which leads to a loss of plasticity. Because of this, during the operation in winter period, failures of structural elements of railway rolling stock and infrastructure increase. Therefore, the task of ensuring the safe service life of high-risk objects of railway transport in north conditions should be based on the establishment of an actual state of metal, mechanisms of damage accumulation, initiation and development of cracks from defects. The article provided is devoted to developing new trends and creating a scientific base to study interrelated processes of deformation, damage and failure; to analyze and develop methods for calculating and depleting the service life of technical equipment of railway transport in order to confirm their safe operation; to develop standards and methods for assessing technology-related risks and their countering in railway transport.

Climate forcing and the initiation of glacier advance during MIS-2 in the North Sikkim Himalaya, India

The present study investigates the relics of the most extensive glacier advances and their retreat in the transitional climatic zone of the Chopta valley, northern Sikkim Himalaya with an aim to understand the forcing factors. The optically stimulated luminescence (OSL) dating of the stratigraphically oldest glacier advance and its retreat in the Chopta valley revealed that the glacier advanced at ∼28 ± 2.8 ka and sustained through the global Last Glacial Maximum (gLGM; 26.5 ka and 19 ka; Mix et al., 2001). The deglaciation is manifested by recessional moraine (ridge) dated at ∼18 ± 2.2 ka. Comparing the results of the present study with the existing glacial chronologies from the Himalayan region, it has been observed that irrespective of the geographical locations; the intensified mid latitude-westerlies during the gLGM and the associated decrease in winter temperature was the major driver of glacier advance during the MIS-2.

Responses of photosynthetic parameters to differences in winter temperatures throughout a temperature gradient in two evergreen tree species

The temperature dependence of photosynthetic parameters has been a focus of interest during recent years owing to its profound implications in the new climate scenario. Many studies have addressed the short-term responses of photosynthetic parameters to temperature change. Less attention has been given to the intraspecific variability in the biochemical parameters of photosynthesis in response to differences in growth temperature. This study explores the effects of winter harshness on the leaf traits of two evergreen tree species (Quercus ilex and Q. suber). Leaf mass per unit area (LMA) and the concentrations of fiber, nitrogen (N), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in both species throughout a temperature gradient. Several photosynthetic parameters [maximum carboxylation rate (V cmax), maximum light-driven electron flux (J max), day respiration rate (R d) and relative stomatal limitation to photosynthesis] were assessed by measuring leaf response curves of net CO2 assimilation versus intercellular CO2 partial pressure. LMA and structural carbohydrate concentrations increased with the decrease in winter temperatures, whereas N concentrations did not show definite patterns. Chlorophyll, soluble proteins, Rubisco, V cmax and J max declined with the decrease in winter temperatures, whereas R d at a set common temperature (25 °C) was higher at colder sites. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates in cold environments is associated with a reduced N allocation to the photosynthetic machinery, which leads to reduced photosynthetic capacity.

Winter Irrigation Effects in Cotton Fields in Arid Inland Irrigated Areas in the North of the Tarim Basin, China

Winter irrigation is one of the water and salt management practices widely adopted in arid irrigated areas in the Tarim Basin located in the Xinjiang Uygur Autonomous Region in the People’s Republic of China. A winter irrigation study was carried out from November 2013 to March 2014 in Korla City. A cotton field was divided into 18 plots with a size of 3 m × 3 m and five winter irrigation treatments (1200 m3/ha, 1800 m3/ha, 2400 m3/ha, 3000 m3/ha, and 3600 m3/ha) and one non-irrigation as a control were designed. The results showed that the higher winter irrigation volumes allowed the significant short-term difference after the irrigation in the fields with the higher soil moisture content. Therefore, the soil moisture in the next sowing season could be maintained at the level which was slightly lower than field capacity and four times that in the non-irrigation treatment. The desalination effect of winter irrigation increased with the increase of water irrigation volume, but its efficiency decreased with the increase of water irrigation volume. The desalination effect was characterized by short-term desalination, long-term salt accumulation, and the time-dependent gradually decreasing trend. During the winter irrigation period, air temperature was the most important external influencing factor of the soil temperature. During the period of the decrease in winter temperatures from December to January, soil temperature in the 5-cm depth showed no significant difference in all the treatments and the control. However, during the period of rising temperatures from January to March, soil temperature in the control increased significantly, faster than that in all treatments. Under the same irrigation volume, the temperature difference between the upper soil layer and the lower soil layer increased during the temperature drop period and decreased during the temperature rise period. In this paper, we proposed the proper winter irrigation volume of 1800–3000 m3/ha and suggested that the irrigation timing should be delayed to early December or performed in several stages in the fields with the drainage system. Under the current strict water management and fixed water supply quota situation, the methods are of great practical significance.

Costs of leaf reinforcement in response to winter cold in evergreen species.

The competitive equilibrium between deciduous and evergreen plant species to a large extent depends on the intensity of the reduction in carbon gain undergone by evergreen leaves, associated with the leaf traits that confer resistance to stressful conditions during the unfavourable part of the year. This study explores the effects of winter harshness on the resistance traits of evergreen leaves. Leaf mass per unit area (LMA), leaf thickness and the concentrations of fibre, nitrogen (N), phosphorus (P), soluble protein, chlorophyll and ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) were determined in three evergreen and two deciduous species along a winter temperature gradient. In the evergreen species, LMA, thickness, and P and structural carbohydrate concentrations increased with the decrease in winter temperatures. Nitrogen and lignin concentrations did not show definite patterns in this regard. Chlorophyll, soluble proteins and Rubisco decreased with the increase in winter harshness. Our results suggest that an increase in LMA and in the concentration of structural carbohydrates would be a requirement for the leaves to cope with low winter temperatures. The evergreen habit would be associated with higher costs at cooler sites, because the cold resistance traits imply additional maintenance costs and reduced N allocation to the photosynthetic machinery, associated with structural reinforcement at colder sites.

'Winter mortality, temperature and influenza' Revisiting Curwen and Devis after a quarter of a century

Objectives: to update the still quoted 25-year-old finding that a drop in winter temperature by 1 oC below its mean is associated with 8,000 excess winter deaths in England and Wales. Methods: time-series regression of excess winter deaths between 1950/1 and 2011/12 on mean outside temperature, influenza and pneumonia deaths and a secular trend. Results: we find that a 1 oC decrease in winter temperature below its mean is associated with 5,100 excess winter deaths. Excess winter mortality has been falling on average by approximately 580 deaths per year. Conclusions: Our revised estimates should supersede Curwen and Devis’s in academic and official publications. Notwithstanding there has been some mitigation in the effects of winter temperature on mortality over the last 60 years, excess winter mortality - given its magnitude- should still be a major source of public health concern in England and Wales. Jose IPARRAGUIRRE, Chief Economist, Age UK, London, United Kingdom, and Universidad de Moron, Buenos Aires, Argentina. London, United Kingdom. E-mail: jose.iparraguirre@ageuk.org.uk . James GOODWIN, Head of Research Department in Age UK, London, United Kingdom.

A multiproxy study of Younger Dryas and Early Holocene climatic conditions from the Grabia River paleo-oxbow lake (central Poland)

Abstract A multi-proxy reconstruction of water depth, temperature and precipitation inferred from Cladocera, Chironomidae and pollen assemblages has been obtained from Świerczyna paleo-oxbow (central Poland) during the Younger Dryas (YD) and Early Holocene. Results suggest that the YD was relatively cold and comprised two main phases. The first (ca. 12,500–12,000 cal. yrs BP) is characterized by a continental climatic regime and a decrease in winter temperatures and precipitation but an increase in spring/summer precipitation. The second phase (ca. 12,000–11,500 cal. yrs BP) was more mild with a variable continental climate, an increase in summer and winter temperature, a lengthening of the growing season and increased annual precipitation. The reconstructed water level generally follows changes in spring and summer precipitation and length of growing season. The frequency and timing of hydroclimatic oscillations at Świerczyna show strong similarities to records from other sites in Europe. This confirms that oxbows and valley mire ecosystems respond to rapid climate change during the YD and Early Holocene. This study therefore brings new insights into the effects of climate changes on river environments, especially during the YD. We also discuss the limitations of water depth, temperature and precipitation reconstructions inferred from the studied biotic assemblages.

A Study of Maximum and Minimum Temperatures Trends at Junagadh (Saurashtra Region) of Gujarat, India

This paper, therefore, attempts to study temporal variation in temperature over Junagadh (Saurashtra Region) of Gujarat, India, India, during the period 1980-2011. The long-term change in temperature has been evaluated by Mann–Kendall rank statistics and linear trend. An important aspect of the present study is the significant cooling trend in mean annual temperature, which is more predominant during winter season. The summer season also shows significant cooling trend due to slightly decrease in Tmax. This cooling trend in Junagadh (Saurashtra Region) Gujarat, India temperature is supported by studies conducted by other researchers (Rupa Kumar and Hingane, 1988). These authors studied the temperature for Junagadh (Saurashtra region) Gujarat, India during the period 1980-2007 and observed a cooling trend, but not significant at any level. Against this background, in the present study, temperature data during the period 1980-2011 have been studied. The result indicates significant slightly decrease in winter temperature at 0.01 level. This suggests that the last decade has witnessed a phenomenal epoch in temperature series, leading to a decreasing trend from non-significant to significant. Contrary to this, the monsoon season shows warming trend. This may be due to significant increase in the low cloud amount during this season. We are still a long way from understanding the complex interaction of many physical processes that determine the evolution of climate.

A new circulation index to describe variations in winter temperature in Southwest China

A new circulation index (I SW) that can realistically describe winter temperature variations over Southwest China is defined based on analysis of the NCEP/NCAR reanalysis data (version 1) and the observations at 585 stations in China. The study period is from January 1961 to February 2011. The relationship between I SW and general circulation patterns in East Asia is also analyzed. Results show that I SW successfully captures the variations in winter temperature over Southwest China. High I SW values correspond to the intensified Mongolian high, the weakened Aleutian low, increases in the strength of the Middle East westerly jet stream over the south of the Tibetan Plateau (TP), and decreases in the strength of the subtropical westerly jet over the north of the TP. Meanwhile, the East Asian trough deepens and extends southwestward, making it easier for the cold air mass from the north to intrude Southwest China along the trough. These circulation patterns lead to a decrease in winter temperature over Southwest China (and vice versa). In addition to the East Asian winter monsoon, the two westerly jets that dominate the upper level circulation over East Asia also exert important influences on winter temperature in Southwest China, especially the Middle East westerly jet to the south of the TP.

Variability of Neogene Continental Climates in Northwest Europe - a detailed Study based on Microfloras

This study presents a detailed continental palaeoclimate record for the Neogene of Northwestern Europe. Palynomorph samples from continental to marginal marine deposits in 5 correlated sections from the Lower Rhine Basin (NW Germany) covering the time-span from Burdigalian to Zanclean are analysed. Independent time-control in the sections is provided by sequence stratigraphy. Based on 1470 microfloras 3 temperature (mean annual temperature, warm and cold month mean) and 4 precipitation variables (mean annual precipitation, mean monthly precipitation in the driest, wettest and warmest month) are quantified using the Coexistence Approach, a method employing climate requirements of Nearest Living Relatives of fossil taxa. In face of known limitations in climatic resolution of microflora-based data, present results confirm the major trends in continental Neogene climate evolution of Northwestern Europe as previously reconstructed from macroflora and, in addition, reveal climate change on shorter time scales. Our data suggest a distinct coupling of continental climate with the marine environmental system. Phases of eustatic sea-level lowstand connected to Neogene glaciation events (Mi events) are mirrored in the continental curves. The continental records also show cyclicity at different scales and amplitudes. Small-scale climate variability we observe in the Mid-Miocene and the Tortonian most probably is paced by eccentricity (100 kyr cycles), in the later part of the Langhian and early Serravallian 400 kyr cycles are expressed as well. Along the time-span regarded climate variability is characterized by non-proportional changes of climate variables. During the Miocene, cooling - mainly expressed by a decrease in winter temperature - commonly was connected to drying. A substantial shift of the climate system is indicated for the Pliocene where warm periods tended to be summer-dry, at the same time higher amplitudes of short-term changes point to decreasing climate stability.