Autumn Air Temperature Research Articles

State of polar climate in 2023

The year 2023 has become the warmest year on global record. As the Antarctic and Arctic are sensitive regions to global warming, the climate changes in 2023 in these regions have attracted widespread attention. In this study, using observations, reanalysis and remote sensing data, we reported detailed polar climate changes in 2023, including warming, sea ice, atmospheric composition and extreme events. Antarctic exhibited large east‒west regional differences and the coexistence of extreme warm and cold events. In Coats Land, Queen Maud Land and the Antarctic Peninsula, three and seven stations recorded the second and third highest autumn air temperatures in history, respectively. The Amundsen–Scott station experienced extreme warming event in July, with the temperature increasing by 40 °C in one day. Abnormal cooling was evident in the Ross Sea and neighboring regions which were predominantly winter (June–August) cold anomalies, with Marylin Station reaching the lowest winter temperature in history. The Arctic experienced the warmest summer after 1979, with an overall distribution of ‘warm land‒cold sea’ on annual average. Compared with the 1991–2020 average, the annual air temperature anomalies reached more than 2 °C in northern Canada and the Barents Sea–Kara Sea coast. Abnormal high summer temperature caused most severe wildfires in Canada on record and second largest daily cumulative melt area over the Greenland ice Sheet daily post-1979. Polar sea ice continued to decrease rapidly, with minimum sea ice extent in Antarctic and Arctic ranking the first and sixth lowest post-1979. For melt season, Arctic Ocean sea ice began to melt later in 2023 than the 2011–2023 average, and freeze onset was delayed due to high temperatures in summer and autumn. Additionally, the status of polar atmospheric greenhouse gases remains bleak, and major greenhouse gas concentrations continue to increase. The Antarctic ozone hole in 2023 formed approximately 10 d earlier and lasted longer than the 1979–2023 average, with a maximum daily area of 2.6 × 107 km2 on 21 September. This summary of polar climate changes in 2023 will help people better understand global climate change and draw attention to polar regions.

The effect of sowing dates and sowing rates of wintering pea varieties on protein percentage and yield of nutrients

There have been presented the study results on determining the quality of grain of wintering peas varieties ‘Fokus’ and ‘Zimus’ depending on agricultural methods. The purpose of the current study was to determine protein percentage and yield of basic nutrients in grain of wintering peas, depending on sowing dates and rates. The current study was carried out at the FSBSI “ARC “Donskoy” in 2019–2021. The soil of the experimental plot was represented by ordinary carbonate heavy loamy chernozem. The forecrop was winter wheat. Weather conditions during the years of study were characterized by increased air temperatures in autumn and the return of cold weather in spring, which led to significant damage and thinning of crops. The amount of productive precipitation during the period of grain filling had a positive effect on productivity formation. There has been found that the greatest collection of basic nutrients was obtained in the second ten days of October with a sowing rate of 1.2 and 1.4 million pcs/ha for the varieties ‘Fokus’ and ‘Zimus’, respectively. For the variety ‘Fokus’, the highest crude protein percentage was 25.42 %, with 2.58 t/ha of feed units, 0.557 t/ha of crude protein, 25.31 GJ/ha of metabolic energy, with 189 g of a supply of a feed unit with digestible protein. For the variety ‘Zimus’, the highest crude protein percentage was 25.46 %, with 2.57 t/ha of feed units, 0.555 t/ha of crude protein, 24.62 GJ/ha of metabolic energy, with 190 g of a supply of a feed unit with digestible protein. The studied varieties according to digestible protein percentage were at the level of 205–219 g per a kg of grain.

Agroclimatic mapping for olive cultivation in Brazil: pinpointing optimal growing regions.

This research aimed to identify the agroclimatic zones in Brazil, excluding Rio Grande do Sul, that are suitable for olive (Olea europaea L.) cultivation, considering both climatic and topographical factors. Olives require specific conditions: moderate winter temperatures (7-15 °C), warmer summers (25-35 °C) and sufficient water during growth and fruit maturation. They can endure some drought, making them a viable option for agricultural diversification. Using daily meteorological data from 1989 to 2023 from NASA-POWER, this study analyzed variables like air temperature (minimum and maximum) and rainfall. Key climate variables were the mean air temperature in winter (T_w), spring (T_s), summer (T_su) and autumn (T_a) and total annual precipitation (Prec). Criteria for suitability included: T_w between 5 and 20 °C, T_s between 15 and 23 °C, T_su between 15 and 30 °C, T_a between 15 and 22 °C, annual precipitation over 900 mm and altitude below 900 m. Geographic information system software and Python 3.8 were employed for data analysis and zoning. Results indicated that only 1.92% of the analyzed area, mainly in Minas Gerais, was suitable for olive cultivation. High temperatures and low rainfall in Brazil, particularly in the North and Midwest, make 59.56% of the country unsuitable for olive farming. Additionally, 18.58% of the land, mainly in the Northeast, faces challenges due to extreme heat (T_w) and insufficient water supply. © 2023 Society of Chemical Industry.

Применение фазового анализа для прогнозирования многолетней динамики температуры атмосферного воздуха

Long-term average values of atmospheric air temperature (annual, autumn, winter, spring and summer) are one of the key points used to make scientifically valid decisions on the adaptation of crops to changing climate and environmental conditions. Despite their widespread use for the analysis and forecasting of various meteorological parameters of the atmosphere, the nature of such series has not yet been sufficiently studied. This determines the relevance of detailed analysis and forecasting of time series of atmospheric air temperature. At the same time, they are considered to be formed under the influence of linear and cyclic factors. To identify cyclical components, one of the most powerful and adequate time series analysis tools called phase analysis is used. In this study, a phase portrait of the time series of average air temperatures for the autumn period at the Nalchik weather station from 1961 to 2022 is constructed for preforecast analysis. To select the most significant periods of quasi-cycles, the theory of fuzzy logic is used. On its basis an algorithm for the formation of a fuzzy set of quasi-cycle lengths is implemented. Further prediction of the values of the time series in the retrospective section is carried out by the least square method. Further forecasting of time series values in the retrospective section is carried out using the least squares method. According to the results of the conducted research, it was found that the proposed model makes it possible to predict the values of average autumn air temperatures with high accuracy (5%). In the time series of average autumn air temperatures, a cycle characteristic of the 11-year cycle of solar activity and its phases is traced. All the quality criteria of the proposed model meet the requirements for the quality and adequacy of forecast models. This model can be applied to the analysis and forecasting of the average values of atmospheric air temperatures for the spring, summer and winter periods, as well as the average annual temperatures in general. The research has shown that the time series characterizing the temperature regime of atmospheric air, which is very complex in nature, can be predicted using phase analysis.

Comparison of two methods for assessing the pollen allergy risk of urban parks in Chengdu City, China

The urban green space is an important inducer of pollen allergy. In recent years, the incidence of pollen allergy in China has increased from 5 % to 17.8 %, and it still rapidly increases. However, only few assessment methods of pollen allergy risk have been developed and applied in the urban green spaces. The feasibility and the accuracies of the assessment results of these methods has been unknown. Therefore, in this paper, the two best-known methods, total pollen concentration monitoring method and urban green zone allergenicity index (IUGZA) method, were both used to assess the pollen allergy risk of the same urban park (the People’s Park of Chengdu City, China). The impact factors and prediction consistency of both models were compared. The results showed that the proportion of medium and highly allergenic tree species reached up to 75.93 % in People’s Park. The total IUGZA value of this park was 0.69. A total of 36,171 pollen grains were collected here. The average pollen concentration of this park was 125.88 grains/cm2 per day. Both methods showed that the pollen allergy risk of the People's Park was the highest in spring. Correlation analysis showed that no vegetation characteristics of this park were correlated with IUGZA values and total pollen concentration. However, pollen concentration was extremely significantly correlated with air temperature and solar radiation in autumn and winter. Kendall’s concordance coefficient identified a super high consistency between total pollen concentration and IUGZA values in this park. This result means that both methods for assessing the risk of pollen allergy are effective. Based on the total pollen concentration, a polynomial formula was established for succinctly calculating the IUGZA. A three-step greening strategy is proposed to minimize the volume of allergen production and increase the well-being of users of urban parks in Chengdu City.

Bell-shaped tree-ring responses to air temperature drive productivity trends in long-lived mountain Mediterranean pines

We investigated the dendroclimatic response of a Pinus heldreichii metapopulation distributed over a wide elevation interval (from 882 to 2143 m a.s.l.), spanning from low mountain to upper subalpine vegetation belts in the southern Italian Apennines. The tested hypothesis is that wood growth along an elevational gradient is non-linearly related to air temperature. During three years of fieldwork (2012–2015) at 24 sites, we collected wood cores from a total of 214 pine trees with diameter at breast height from 19 to 180 cm (average 82.7 ± 32.9 cm). We used a combination of tree-ring and genetic methods to reveal factors involved in growth acclimation using a space-for-time approach. Scores from canonical correspondence analysis were used to combine individual tree-ring series into four composite chronologies related to air temperature along the elevation gradient. Overall, the June dendroclimatic response followed a bell-shaped thermal niche curve, increasing until a peak around 13–14 °C. A similarly bell-shaped response was found with previous autumn air temperature, and both dendroclimatic signals interacted with stem size and growth rates, generating a divergent growth response between the top and the bottom of the elevation gradient. Increased tree growth in the upper subalpine belt was consistent with the consequences of increasing air temperature under no drought stress. A positive link was uncovered between pine growth at all elevations and April mean temperature, with trees growing at the lowest elevations showing the strongest growth response. No elevational genetic differences were found, hence long-lived tree species with small geographical ranges may reverse their climatic response between the lower and upper bioclimatic zones of their environmental niche. Our study revealed a high resistance and acclimation capability of Mediterranean forest stands, and such low vulnerability to changing climatic conditions highlights the potential to store carbon in these ecosystems for the coming decades.

Vegetation Greening, Extended Growing Seasons, and Temperature Feedbacks in Warming Temperate Grasslands of China

Abstract Vegetation activity and phenology are significantly affected by climate change, and changes in vegetation activity and phenology can in turn affect regional or global climate patterns. As one of the world’s great biomes, temperate grasslands have undergone remarkable changes in recent decades, but the connections between vegetation activity and phenology changes and regional climate there have remained unclear. Using the observation minus reanalysis (OMR) method, this study investigated the possible effects of vegetation activity and vegetation growing season changes on air temperatures in temperate grasslands of China. The results showed that average NDVI of the temperate grassland significantly increased by 0.011 decade−1 for the growing season during 1982–2015. The growing season started earlier and ended later, resulting in an extension. Increased vegetation activity during spring and autumn significantly warmed spring and autumn air temperatures by reducing albedo. By contrast, summer greening had no significant effect on summer temperature, due to the opposing effects of decreased albedo and enhanced evapotranspiration on temperature. The earlier start and later end of the growing season contributed to warmer spring and autumn air temperatures. As phenological changes had no significant effect on summer temperature, the extended growing season warmed air temperature. Our results suggest that the climate change–induced increasing vegetation activity and extended growing seasons can further aggravate regional warming in temperate grasslands of China, implying that the effects of vegetation activity and phenology changes on regional climate should be considered in climate models for accurately simulating climate change in temperate grasslands.

The analysis of annual and seasonal surface air temperature trends of southern and southeastern Bosnia and Herzegovina from 1961 to 2017

In some areas of the world, regional climate change is in good agreement with global climate change. This study brings new information about what defines climate change in the contact area of Adriatic Sea and Southeastern Europe, and conclusions are based on trend analysis of annual and seasonal temperatures in the southern and southeastern parts of Bosnia and Herzegovina. Trend analysis was applied on mean annual surface air temperatures, mean maximum temperatures, and mean minimum temperatures of all four seasons. This study used 4 meteorological stations: Livno, Bileća, Mostar, and Ivan Sedlo for 56 years. The main statistical method is the Mann-Kendall test. The total number of analysis is 48. A statistically significant positive trend was determined in 36 analysis, while in the rest of the tests this was not the case. The highest amount of temperature increase is present in the mean maximum summer air temperatures in Livno and Ivan Sedlo. Mean minimum autumn air temperatures had the smallest increase. Negative trend is present in the mean autumn surface air temperatures and mean maximum autumn temperatures. Using a geographical information system resulted in visualizing regional differences in the spatial distribution of isotherms. The study area has combined the influence of orography and maritime effects of the Adriatic Sea. Having in mind these results, the growing temperature has been recognized as a problem which needs more attention in Bosnia and Herzegovina. Unfortunately, official documents which propose economic adaptation on climate change in this country are not at a satisfactory level.

Relationship between Arctic Sea Ice in Autumn and Subsequent July Air Temperature over East Asia and the Western North Pacific

Relationship between Arctic Sea Ice in Autumn and Subsequent July Air Temperature over East Asia and the Western North Pacific

Rapid soil and vegetation changes at regional scale in continental Antarctica

Antarctica is the last pristine environment on Earth, its biota being adapted to the harsh and extreme polar climate. Until now, soil formation and vegetation development in continental Antarctica were considered very slow due to the extreme conditions of this polar desert. Since the austral summer 2002/2003, a long-term monitoring network of the terrestrial ecosystems (soils, vegetation, active layer thickness) has been established at Victoria Land (VL) across a > 500 km latitudinal gradient of coastal sites (73°–77°S). In only one decade large ecosystem changes were detected. Climate was characterized by a significant increase of thawing degree days in northern VL and of autumn air temperature. No extreme climatic events (such as hot spells) where detected in the study period. Soil chemistry suffered large quantitative changes, clearly indicating rapid pedogenetic processes. In most soils the upper layers exhibited a strong alkalinization (pH increases up to 3 units) and increases in conductivity, anions and cations (in particular of SO4 and Na). The largest changes were observed in soils with low vegetation cover. Statistically significant differences in soil chemistry were detected between soils with high and low vegetation cover, the former showing lower pH, conductivity, Na and Cl. Most plots exhibited changes of total cover, species richness and floristic composition, with vegetation expansion in soils with low vegetation cover and the largest increase recorded at Apostrophe Island (northern VL). Principal Component Analysis (PCA) identified the main trend of vegetation change, with a shift from lower to higher cover and a secondary trend of change associated with a gradient of water availability, consistent with an increase in water instead of snow. Redundancy analysis (RDA) identified the trend of change in soil chemistry with increases in pH, conductivity, anions and cations associated with the concomitant decrease in C, N, NO3, PO4. The RDA confirmed that soil changes were associated with a gradient of vegetation change (from low to high cover) as well as of water availability, as already indirectly outlined by the PCA. Field manipulation experiments carried out at five locations of the network between 73°S and 77°S, simulating increases of precipitation from snow or water additions didn’t induce changes in soil pH, indicating that pulse events of snow accumulation or melting could not trigger persistent soil pH changes. These data allow hypothesize the occurrence of a main ecosystem change occurring at regional scale at Victoria Land. The slight air warming and its consequences on soil chemistry and vegetation, further highlight the sensitivity of the fragile Antarctic ecosystems to the consequences of even small changes in climate.

Efficiency of dung application on rice agroecosystems in Kuban

The effect of the combined application of dung and nitrification inhibitor Entec FL DMPP on the loss of ammonium nitrogen from meadow chernozem soil (corresponding to Gleyic Chernozem in WRB) under the conditions of rice cultivation in the Kuban was studied. On the rice irrigation system, a field experiment was performed with autumn and spring incorporation of dung at a rate of 30 t/ha, both separately and with the addition of a nitrification inhibitor against the background of mineral fertilizers. It was found that the inclusion of a nitrification inhibitor in the dung contributed to a decrease in nitrogen losses by 6.7-15.0% during their incorporation in autumn and by 10.8-18.1% in spring, occurring as a result of denitrification and leaching of nitrates, and optimum conditions of nitrogen nutrition for rice plants. A less pronounced effect of the nitrification inhibitor was noted during its autumn incorporation with dung, which is associated with a lower air temperature in autumn and a longer period from fertilization to rice sowing.

The chilling requirement of subtropical trees is fulfilled by high temperatures: A generalized hypothesis for tree endodormancy release and a method for testing it

ABSTRACT Spring phenology is a key phenomenon mediating the effects of climate change on terrestrial plants and ecosystems, but in regard to subtropical trees, the dormancy mechanisms that regulate spring phenology are still poorly understood. It has been suggested recently that similarly to temperate and boreal trees, subtropical tree species also show endodormancy and a chilling requirement of endodormancy release. However, there are no previous experimental results on the chilling temperature range that is effective for endodormancy release in subtropical trees. We studied endodormancy and the chilling requirement in four subtropical tree species experimentally. In addition to chilling in natural conditions, we applied controlled chilling at several constant temperatures ranging from -2 to +15 °C. Our results show endodormancy and a chilling requirement in the tree species studied and reveal several differences among the four species in the manifestation and depth of endodormancy. Most importantly, our findings indicate that contrary to the prevailing mainline conception that chilling temperatures are generally restricted to those below +10 °C, higher temperatures of up to +15 °C are also effective for endodormancy release in the subtropical tree species examined. An exact upper threshold of +10.4 °C has been experimentally established for boreal Betula pubescens. We hypothesized that this difference would be explained by differences in the occurrence of low autumn temperatures between the two respective climates. We developed a method for testing the hypothesis by analysing long-term climatic records in relation to the experimental findings. Tentative results supported our hypothesis. On the basis of this novel result, we put forward the testable generalized hypothesis that in any climatic conditions where trees show endodormancy, the range of temperatures physiologically effective in endodormancy release represents the range of typical autumn air temperatures occurring in those particular climatic conditions.

Assessment of nonlinear effects of a deep subgrid lake with an atmospheric single‐column model

AbstractSome nonlinear aspects due to the coupling of a single column atmospheric model (SCM) with both a land‐surface model (LSM) and a lake model has lately been published by Goyette in 2017. In this previous study, the surface type abruptly changed from land to an open water surface. This article further investigates the potential of this SCM to explore the nonlinear effects through the analysis of the impacts of fractional land and open water surfaces on the surface fluxes and variables, as well as on the atmospheric air temperature, specific humidity, and wind speed vertical profiles, with an application to deep Lake Geneva, Switzerland. It is shown that the coupling methodology depending on the surface type produced realistic and coherent results and indicated that the mean fluxes and other relevant quantities may not be simply averaged on the basis of the fractional area of the land and that of the open water. If Lake Geneva relative surface area is prescribed to its observed value with respect to the model grid‐mesh size, the remaining being land surface, results showed maximum seasonal mean differences of 7.5 and 5.4 W·m−2 for the latent and sensible heat flux in Autumn respectively, 1.6°C, 0.8 g·kg−1 for the screen‐level air temperature and specific humidity in Autumn respectively, and 0.6 m·s−1 for the anemometer‐level windspeed in Winter with respect to the original land surface, owing to the different behaviour of the vertical turbulent transfer of heat, moisture and momentum but also to the different thermal and radiative characteristics of land and water surfaces.

Spatiotemporal variability of snow cover timing and duration over the Eurasian continent during 1966–2012

The timing and duration of snow cover critically affect surface albedo, surface energy budgets, and hydrological processes. Previous studies using in-situ or satellite remote sensing data have mostly been site-specific (Siberia and the Tibetan Plateau), and remote sensing and/or modeling data include large uncertainties. Here, we used 1103 stations with long-term (1966–2012) ground-based snow measurements to investigate spatial and temporal variability in snow cover timing and duration and factors impacting those changes across the Eurasian continent. We found the earliest annual onset and latest disappearance of snow cover occurred along the Arctic coast, where the long-term (1971–2000) mean annual snow cover duration (SCD) was more than nine months which was the longest in this study. The shortest SCD, ≤10 days, was found in southern China. The first and last dates of snow cover (FD and LD, respectively), SCD, and the ratio of SCD to snow season length (RDL) were generally latitude dependent over the Eurasian Continent, while were elevation dependent on the Tibetan Plateau. During the period from 1966 through 2012, FD delayed and LD advanced by ~1 day/decade, and RDL increased by about 0.01/decade. The LD, SCD, and RDL anomalies (relative to the period 1971–2000) were also significantly correlated with latitude. Advances in LD and positive RDL were more significant in low-latitude regions, decreases in SCD were more significant in high-latitude regions. Changes in SCD were related to air temperature and snowfall in autumn and warming in spring. SCD specifically increased in the northern Xinjiang and northeastern China due to increased snowfall. The significant reduction in SCD in southwestern Russia, the Tibetan Plateau and along the Yangtze River was mainly affected by climate warming.

Changing River Ice Seasonality and Impacts on Interior Alaskan Communities

Abstract Subsistence harvesters in high latitudes rely on frozen rivers for winter access to local resources. During recent decades, interior Alaskan residents have observed changes in river ice regimes that are significant hindrances to travel and subsistence practices. We used remote sensing in combination with local observations to examine changes in seasonality of river breakup and freeze-up and to assess the implications on travel for subsistence harvesters. Spring and autumn air temperatures, respectively, were found to impact timing of breakup (−2.0 days °C−1) and freeze-up (+2.0 days °C−1). Spring air temperatures have increased by 0.2°–0.6°C decade−1 over the last 62–93 years, depending on study area and time period. Local observations indicate that the breakup season has advanced by about 6 days over the last century. Autumn air temperatures have not changed over the long term, but have been generally warmer over the last 15 years. Over various time periods throughout the last century, we found no change in freeze-up timing for some communities, whereas other communities showed delays of 1.0–2.1 days decade−1. The length of time the river was unsafe for travel during the freeze-up season was 2 to 3 times greater than during breakup. The duration of river ice cover for safe travel has declined over the last century and is expected to decline further as the climate continues to warm, thereby presenting new challenges to accessing subsistence resources and necessitating community adaptation.

Investigation into sensitivities of factors in outdoor thermal comfort indices

With the development of the urban city, increasing attention has been paid to outdoor thermal comfort. In this paper, an analysis of the sensitivities of different factors, including the personal factors and physical parameters of the thermal environment was conducted. The results showed that there was a strong linear relationship between the Physiological Equivalent Temperature (PET) and operation temperature. When the operation temperature was lower than 32 °C, the effect of air velocity on the PET was positive. However, the effects of other factors, including relative humidity, clothing insulation, and metabolic rate, on the PET were insignificant. An exponential relationship was found between the UTCI and the operation temperature. The effect of air velocity change on the UTCI became weaker and weaker with the increase of operation temperature. Compared with the PET, the linear relationship between the UTCI and relative humidity was clearer. A field survey of thermal comfort carried out in Guangzhou University was used for the validation of the thermal comfort models. It was observed that the clothing insulation requirement increased with the decrease of air temperature in autumn. The variations in metabolic rate were also obvious, from 1met to 3.8 met. More than 70% of the people had been walking before they arrived at the survey locations. In addition, there were some differences in the neutral PET and UTCI temperature between the metabolic rates of 1.0–2.0 met and of 2.6 met. Meanwhile, models of MTSV against the PET and UTCI under different metabolic rates were established.

Quantifying air temperature evolution in the permafrost region from 1901 to 2014

ABSTRACTPermafrost is sensitive to climate change. In recent decades, a growing body of research has focused mainly on the study of permafrost thaw, but leaving the climate change in the permafrost region that has not been adequately assessed, which is of first importance for the research on permafrost thaw. Using gridded observations from the Climatic Research Unit (CRU), in conjunction with the European Centre for Medium‐Range Weather Forecasts Reanalysis Interim (ERA‐Interim) and Japanese 55‐year Reanalysis (JRA‐55) data, this study investigates characteristics of air temperature evolution in the region of permafrost throughout the 20th century. Results show that yearly air temperatures in the permafrost region of the Northern Hemisphere experienced a statistically significant warming, with trends of 0.13 °C decade−1 for 1901–2014 and 0.40 °C decade−1 for 1979–2014. Winter air temperatures showed the greatest increase during 1901–2014, while autumn air temperatures increased the most during 1979–2014. In addition, increases in air temperature in high‐latitude permafrost sub‐region are greater than those in high‐elevation permafrost sub‐region, and air temperatures in the permafrost sub‐region of Mongolia have the largest trend from 1901 to 2014, followed by those in Russia, Alaska, Canada, and China. Air temperatures in the permafrost region increased 1.7 times more than temperatures globally from 1901 to 2014, and underwent an increase at a rate of 0.32 °C decade−1 during the period 1998–2014, when the global warming hiatus occurred with a trend of 0.06 °C decade−1. This implies that permafrost thaw may have continued during the global warming hiatus period. The close agreement between CRU data and ERA‐Interim and JRA‐55 reanalysis data indicates good reliability of air temperature evolution characteristics. These results provide information relevant to climate change in the permafrost region, and are useful for researching and understanding historical permafrost change.

Arctic sea ice cover in connection with climate change

Recently published studies on key issues in the evolution of Arctic sea ice cover are reviewed and attempts to answer disputable questions are made in the research part of the work. It is shown that climate warming, manifested in an increase in the surface air temperature, and reduction in the ice cover develop with a high degree of agreement in summer. Based on this fact, anomalies of the September ice-cover area have been retrieved from 1900. They show a significant decrease in the 1930–1940s, which is almost twice as low as in 2007–2012. The influence of fluctuations in the flow of warm and salty Atlantic water is noted in variations in the winter maximum of the ice-cover area in the Barents Sea. An accelerated positive trend has been ascertained for the air temperature in late autumn–early winter in 1993–2012 due to an increase in the open water area in late summer. Inherent regularities of the ice-cover-area variability made it possible to develop a prediction of the monthly values of sea-ice extent with a head time from 6 months to 2 years. Their strong correlation with summer air temperature is used to estimate the onset of summer ice clearance in the Arctic.

Climate processes in the nival-glacial zone of Trans-Ili Alatau and their impact on mountain glaciation and runoff

On the basis of the latest monitoring data of a high-mountainous glaciological station of Institute of Geography, Republic of Kazakhstan on modern climate changes in the nival-glacial zone and their occurrences in the mode of river runoff are analyzed. Tendencies of changes of the 10 meteorological elements for various intervals of averaging as for the years 1971–2011 are studied (winter, summer and annual mass balance of Central Tujyksu Glacier and annual runoff of the rivers of Ili river basin). Results of the analysis confirm continuation of climate warming in the region; the air temperature in nival-glacial zone raised is commensurable to growth of temperatures in foothill and low mountain zones; the dates of the beginning of snow melting and dates of stable transition of air temperature through 0 °C in the spring and on later terms in the autumn moved for the earlier time; the quantity of precipitation tended to increase especially for the cold period and July. Average temperatures of the cold period grew more intensively than in the summer period. Warming of the nival-glacial zone induced not only due to increase of summer temperatures, but also due to appreciable increase of autumn air temperatures especially in September as well as due to increases of the warm period duration. Starting from 1975 the significant positive trend in long-term fluctuations of runoff for all researched rivers is observed. For the period 1975–2011, steady growth of seasonal snow cover depth in the nival-glacial and middle-mountainous zones of Zailiyskiy Alatau is observed. Positive changes in the fluctuations of winter, summer and annual mass balance of glacier are observed. Nowadays natural climatic influences to the rivers runoff in Ili-Balkash region and renewed surface water resources exceed anthropogenic influences which were determining in the zone of runoff dispersion during the low-flow period.

Sensitivity of cold acclimation to elevated autumn temperature in field-grown Pinus strobus seedlings.

Climate change will increase autumn air temperature, while photoperiod decrease will remain unaffected. We assessed the effect of increased autumn air temperature on timing and development of cold acclimation and freezing resistance in Eastern white pine (EWP, Pinus strobus) under field conditions. For this purpose we simulated projected warmer temperatures for southern Ontario in a Temperature Free-Air-Controlled Enhancement (T-FACE) experiment and exposed EWP seedlings to ambient (Control) or elevated temperature (ET, +1.5°C/+3°C during day/night). Photosynthetic gas exchange, chlorophyll fluorescence, photoprotective pigments, leaf non-structural carbohydrates (NSC), and cold hardiness were assessed over two consecutive autumns. Nighttime temperature below 10°C and photoperiod below 12 h initiated downregulation of assimilation in both treatments. When temperature further decreased to 0°C and photoperiod became shorter than 10 h, downregulation of the light reactions and upregulation of photoprotective mechanisms occurred in both treatments. While ET seedlings did not delay the timing of the downregulation of assimilation, stomatal conductance in ET seedlings was decreased by 20–30% between August and early October. In both treatments leaf NSC composition changed considerably during autumn but differences between Control and ET seedlings were not significant. Similarly, development of freezing resistance was induced by exposure to low temperature during autumn, but the timing was not delayed in ET seedlings compared to Control seedlings. Our results indicate that EWP is most sensitive to temperature changes during October and November when downregulation of photosynthesis, enhancement of photoprotection, synthesis of cold-associated NSCs and development of freezing resistance occur. However, we also conclude that the timing of the development of freezing resistance in EWP seedlings is not affected by moderate temperature increases used in our field experiments.