Science.gov

Sample records for extreme winter warming

  1. Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community.

    PubMed

    Bokhorst, Stef; Bjerke, Jarle W; Davey, Matthew P; Taulavuori, Kari; Taulavuori, Erja; Laine, Kari; Callaghan, Terry V; Phoenix, Gareth K

    2010-10-01

    Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate spring-like development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more

  2. The Extremely Warm Early Winter 2000 in Europe: What is the Forcing

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Angell, J. K.; Atlas, R.; Ardizzone, J.; Demaree, G.; Jusem, J. C.; Koslowsky, D.; Terry, J.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    High variability characterizes the winter climate of central Europe: interannual fluctuations in the surface-air temperature as large as 18 C over large areas are fairly common. The extraordinary early-winter 2000 in Europe appears to be a departure to an unprecedented extreme of the existing climate patterns. Such anomalous events affect agriculture, forestry, fuel consumption, etc., and thus deserve in-depth analysis. Our analysis indicates that the high anomalies of the surface-air temperature are predominantly due to the southwesterly flow from the eastern North Atlantic, with a weak contribution by southerly flow from the western Mediterranean. Backward trajectories based on the SSM/I and NCEP Reanalysis datasets traced from west-central Europe indicate that the warm air masses flowing into Europe originate in the southern North Atlantic, where the surface-air temperatures exceed by 15c or more the climatic norms in Europe for late-November or early-December. Because such large ocean-to-continent temperature differences characterize the winter conditions, we refer to this episode which started in late November as occurring in the early winter. In this season, with the sun low over the horizon in Europe, absorption of insolation by the surface has little significance. The effect of cloudiness, a corollary to the low-level maritime-air advection, is a warming by a reduction of heat loss (greenhouse effect). In contrast, in the summer, clouds, by reducing absorption of insolation, produce a cooling, effect at the surface.

  3. Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard.

    PubMed

    Semenchuk, Philipp R; Elberling, Bo; Cooper, Elisabeth J

    2013-08-01

    The High Arctic winter is expected to be altered through ongoing and future climate change. Winter precipitation and snow depth are projected to increase and melt out dates change accordingly. Also, snow cover and depth will play an important role in protecting plant canopy from increasingly more frequent extreme winter warming events. Flower production of many Arctic plants is dependent on melt out timing, since season length determines resource availability for flower preformation. We erected snow fences to increase snow depth and shorten growing season, and counted flowers of six species over 5 years, during which we experienced two extreme winter warming events. Most species were resistant to snow cover increase, but two species reduced flower abundance due to shortened growing seasons. Cassiope tetragona responded strongly with fewer flowers in deep snow regimes during years without extreme events, while Stellaria crassipes responded partly. Snow pack thickness determined whether winter warming events had an effect on flower abundance of some species. Warming events clearly reduced flower abundance in shallow but not in deep snow regimes of Cassiope tetragona, but only marginally for Dryas octopetala. However, the affected species were resilient and individuals did not experience any long term effects. In the case of short or cold summers, a subset of species suffered reduced reproductive success, which may affect future plant composition through possible cascading competition effects. Extreme winter warming events were shown to expose the canopy to cold winter air. The following summer most of the overwintering flower buds could not produce flowers. Thus reproductive success is reduced if this occurs in subsequent years. We conclude that snow depth influences flower abundance by altering season length and by protecting or exposing flower buds to cold winter air, but most species studied are resistant to changes. Winter warming events, often occurring

  4. Snow cover and extreme winter warming events control flower abundance of some, but not all species in high arctic Svalbard

    PubMed Central

    Semenchuk, Philipp R; Elberling, Bo; Cooper, Elisabeth J

    2013-01-01

    Abstract The High Arctic winter is expected to be altered through ongoing and future climate change. Winter precipitation and snow depth are projected to increase and melt out dates change accordingly. Also, snow cover and depth will play an important role in protecting plant canopy from increasingly more frequent extreme winter warming events. Flower production of many Arctic plants is dependent on melt out timing, since season length determines resource availability for flower preformation. We erected snow fences to increase snow depth and shorten growing season, and counted flowers of six species over 5 years, during which we experienced two extreme winter warming events. Most species were resistant to snow cover increase, but two species reduced flower abundance due to shortened growing seasons. Cassiope tetragona responded strongly with fewer flowers in deep snow regimes during years without extreme events, while Stellaria crassipes responded partly. Snow pack thickness determined whether winter warming events had an effect on flower abundance of some species. Warming events clearly reduced flower abundance in shallow but not in deep snow regimes of Cassiope tetragona, but only marginally for Dryas octopetala. However, the affected species were resilient and individuals did not experience any long term effects. In the case of short or cold summers, a subset of species suffered reduced reproductive success, which may affect future plant composition through possible cascading competition effects. Extreme winter warming events were shown to expose the canopy to cold winter air. The following summer most of the overwintering flower buds could not produce flowers. Thus reproductive success is reduced if this occurs in subsequent years. We conclude that snow depth influences flower abundance by altering season length and by protecting or exposing flower buds to cold winter air, but most species studied are resistant to changes. Winter warming events, often

  5. Labile aluminium chemistry downstream a limestone treated lake and an acid tributary: effects of warm winters and extreme rainstorms.

    PubMed

    Andersen, Dag O

    2006-08-01

    The outlet from the limestone treated Lake Terjevann consisted mainly of well-mixed lake water (mean pH 6.1) during the ice-free seasons including the unusually warm winters of 1992 and 1993. However, during the ice-covered period acidic water (mean pH 4.8, mean inorganic aluminium (Al(i)) about 160 microg/l) from the catchment draining under the lake ice dominated. A downstream tributary was generally acid and rich in aluminium (mean pH 4.6, Al(i) about 230 microg/l). After an extreme rainstorm loaded with sea-salts cation exchange in the soil resulted in more than a doubling of the Al(i) concentration (reaching about 500 microg/l). It took 3-4 months until the Al(i) concentration returned to pre-event levels. During the ice-covered period, the acidic outlet and tributary waters resulted in acidic conditions below the confluence (pH<4.8, Al(i) about 150 microg/l) while during the ice-free periods the more neutral outlet water resulted in higher pH and lower Al(i) concentrations (pH>5.2, Al(i) about 95 microg/l). However, during the latter climatic conditions the water was most probably more harmful to fish due to hydrolysing and polymerizing aluminium. After the sea-salt event, the increased Al(i) concentration in the tributary made the zone below the confluence potentially more toxic (pH approximately 5, Al(i) approximately 250 microg/l). Expected global warming resulting in winter mean temperatures above 0 degrees C may eliminate the seasonal acidification of the outlet from limestone-treated lakes creating permanent toxic mixing zones in the confluence below acidic aluminium-rich tributaries. Besides, more frequent rainstorms as a consequence of global warming may increase the frequency of sea-salt events and the Al(i) concentrations in the mixing zones.

  6. Labile aluminium chemistry downstream a limestone treated lake and an acid tributary: effects of warm winters and extreme rainstorms.

    PubMed

    Andersen, Dag O

    2006-08-01

    The outlet from the limestone treated Lake Terjevann consisted mainly of well-mixed lake water (mean pH 6.1) during the ice-free seasons including the unusually warm winters of 1992 and 1993. However, during the ice-covered period acidic water (mean pH 4.8, mean inorganic aluminium (Al(i)) about 160 microg/l) from the catchment draining under the lake ice dominated. A downstream tributary was generally acid and rich in aluminium (mean pH 4.6, Al(i) about 230 microg/l). After an extreme rainstorm loaded with sea-salts cation exchange in the soil resulted in more than a doubling of the Al(i) concentration (reaching about 500 microg/l). It took 3-4 months until the Al(i) concentration returned to pre-event levels. During the ice-covered period, the acidic outlet and tributary waters resulted in acidic conditions below the confluence (pH<4.8, Al(i) about 150 microg/l) while during the ice-free periods the more neutral outlet water resulted in higher pH and lower Al(i) concentrations (pH>5.2, Al(i) about 95 microg/l). However, during the latter climatic conditions the water was most probably more harmful to fish due to hydrolysing and polymerizing aluminium. After the sea-salt event, the increased Al(i) concentration in the tributary made the zone below the confluence potentially more toxic (pH approximately 5, Al(i) approximately 250 microg/l). Expected global warming resulting in winter mean temperatures above 0 degrees C may eliminate the seasonal acidification of the outlet from limestone-treated lakes creating permanent toxic mixing zones in the confluence below acidic aluminium-rich tributaries. Besides, more frequent rainstorms as a consequence of global warming may increase the frequency of sea-salt events and the Al(i) concentrations in the mixing zones. PMID:16269168

  7. Winter warming from large volcanic eruptions

    SciTech Connect

    Robock, A.; Mao, J.

    1992-01-01

    An examination of the Northern Hemisphere winter surface temperature patterns after the 12 largest volcanic eruptions from 1883-1992 shows warming over Eurasia and North America and cooling over the Middle East which are significant at the 95 percent level. This pattern is found in the first winter after tropical eruptions, in the first or second winter after midlatitude eruptions, and in the second winter after high latitude eruptions. The effects are independent of the hemisphere of the volcanoes. An enhanced zonal wind driven by heating of the tropical stratosphere by the volcanic aerosols is responsible for the regions of warming, while the cooling is caused by blocking of incoming sunlight.

  8. Impact of warm winters on microbial growth

    NASA Astrophysics Data System (ADS)

    Birgander, Johanna; Rousk, Johannes; Axel Olsson, Pål

    2014-05-01

    Growth of soil bacteria has an asymmetrical response to higher temperature with a gradual increase with increasing temperatures until an optimum after which a steep decline occurs. In laboratory studies it has been shown that by exposing a soil bacterial community to a temperature above the community's optimum temperature for two months, the bacterial community grows warm-adapted, and the optimum temperature of bacterial growth shifts towards higher temperatures. This result suggests a change in the intrinsic temperature dependence of bacterial growth, as temperature influenced the bacterial growth even though all other factors were kept constant. An intrinsic temperature dependence could be explained by either a change in the bacterial community composition, exchanging less tolerant bacteria towards more tolerant ones, or it could be due to adaptation within the bacteria present. No matter what the shift in temperature tolerance is due to, the shift could have ecosystem scale implications, as winters in northern Europe are getting warmer. To address the question of how microbes and plants are affected by warmer winters, a winter-warming experiment was established in a South Swedish grassland. Results suggest a positive response in microbial growth rate in plots where winter soil temperatures were around 6 °C above ambient. Both bacterial and fungal growth (leucine incorporation, and acetate into ergosterol incorporation, respectively) appeared stimulated, and there are two candidate explanations for these results. Either (i) warming directly influence microbial communities by modulating their temperature adaptation, or (ii) warming indirectly affected the microbial communities via temperature induced changes in bacterial growth conditions. The first explanation is in accordance with what has been shown in laboratory conditions (explained above), where the differences in the intrinsic temperature relationships were examined. To test this explanation the

  9. a Climatology of Extreme Minimum Winter Temperatures in Ohio

    NASA Astrophysics Data System (ADS)

    Edgell, Dennis Joe

    The Extreme Minimum Winter Temperature (EMWT) is the coldest temperature recorded each winter at a given weather station. This variable is a measure of winter temperature stress. Extreme cold influences the geographic distribution of plants, and is a prime control for the production of some valuable fruit crops grown in Ohio. EMWT values are often used to map plant hardiness zones, however the magnitude of EMWT and the date that it occurs has varied widely from year to year. Climatic variables rarely remain constant over time, and the plant hardiness zones could shift significantly if the climate changes and there is a trend towards warmer EMWTs. Plants that have their present geographic ranges limited by cold winter temperatures could increase their spatial extent. Furthermore, EMWT has impacts on human health and has applications for architecture. EMWTs at eighty-nine weather stations in Ohio were analyzed. Summary statistics and return period intervals for critical EMWTs are tabulated and mapped. Return period maps may be more useful for environmental planning than plant hardiness zone maps based on average EMWT, especially in a variable climate. Graphical methods, curve fitting and a probability model for the mean were utilized to examine the long term trend. The EMWT has not warmed during the known climatic record of this variable in Ohio. This study demonstrates the need for more applied climatological studies based on the observed climate record, not obscured by the assumptions of the global warming paradigm.

  10. Global warming and extreme storm surges

    NASA Astrophysics Data System (ADS)

    Grinsted, Aslak

    2013-04-01

    I will show empirical evidence for how global warming has changed extreme storm surge statistics for different regions in the world. Are there any detectable changes beyond what we expect from sea level rise. What does this suggest about the future of hurricane surges such as from hurricane Katrina and superstorm Sandy?

  11. Properties of stratospheric warming events during northern winter.

    NASA Astrophysics Data System (ADS)

    Maury, Pauline; Claud, Chantal; Manzini, Elisa; Hauchecorne, Alain; Keckhut, Philippe

    2015-04-01

    During wintertime the polar mid-stratosphere is characterized by the setting up of westerly winds around the pole; the so-called polar vortex. The polar vortex is one of the most variable features of the zonal-mean circulation of the earth atmosphere, due to a highly non linear interaction between planetary-scale Rossby waves and the zonal flow. Indeed, the interaction between the upward tropospheric propagating waves and the polar vortex leads to a zonal flow weakening, implying a large day to day vortex variability. In the most dramatic cases the polar vortex breaks down, the stratospheric polar flow can reverse its direction and the temperatures can rise locally by more than 50K in a span of a few days. Such phenomena are known as Sudden Stratospheric Warmings (SSWs) and constitute, since their discovery, the most impressive dynamical events in the physical climate system. There are however situations where the polar vortex does not break down, but temperatures increase dramatically. In this study, we propose a global characterization of stratospheric warmings situations based on a temperature threshold in the 50-10hPa layer, in order to assess the properties of daily stratospheric temperature variability during the northern winter. The originality of this approch consists in evaluating the wintertime positive temperature anomalies in terms of intensity and duration. We will show that there is a wide spectrum of warming types. The major SSWs are the most extreme, but there are other events that share some common properties with the major ones. Though neglected, these latter warmings may play a key role in the coupling of the stratosphere-troposphere system.

  12. Changes in Arctic warm and cold spell occurrence during winter and summer

    NASA Astrophysics Data System (ADS)

    Matthes, Heidrun; Rinke, Annette; Dethloff, Klaus

    2016-04-01

    In the Arctic, climate change manifests with the strongest warming trends on the globe, especially in the cold season, associated with Arctic Amplification. However, climate change is not restricted to mean temperature but also expresses itself in changes of temperature extremes. It is under debate if climate extremes change similarly strong, and what mechanisms apply. Our study provides detailed regional information about two selected temperature extreme indices in the Arctic, namely warm and cold spells in winter and summer. Both indices detect lasting cold respectively warm periods that are based on extreme temperatures: cold nights as days where the daily minimum temperature is below the 10th percentile of minimum temperatures and warm day times where the daily maximum temperature is above the 90th percentile of maximum temperatures. We analyze the temporal evolution and variability of warm and cold spells from 1979-2013, based on daily station data and the ERA-Interim reanalysis. Calculated trends from both datasets suggest a widespread decrease of cold spells in winter and summer of up to -4 days/decade, with regional patches where trends are statistically significant throughout the Arctic. Winter trends are spatially heterogeneous, the reanalysis also shows small areas with statistically significant increases of cold spells throughout Siberia. Calculated changes in warm spells from both datasets are mostly small throughout the Arctic (below ± 1 day/decade) and statistically not significant. Remarkable exceptions are the Lena river basin in winter with a statistically significant decrease of up to 1.5 days/decade and areas in Scandinavia with statistically significant increases of up to 2.5 days/decade in winter and summer (again from both datasets). Changes in both warm and cold spells may be caused by two separate mechanisms: changes in occurrence of the underlying extremes (changes in the number of cold nights and warm daytimes) or changes in the temporal

  13. Recent high mountain rockfalls and warm daily temperature extremes

    NASA Astrophysics Data System (ADS)

    Allen, S. K.; Huggel, C.

    2012-04-01

    temperatures in the 7 days prior to failure, (between 6 - 9°C above average), and in three of these cases, temperatures exceeded even the 99th percentile. A further 3 events occurring in this region during the longer term heatwave of 2003 similarly were also preceded by extreme daily maximum temperatures. This relationship holds for other failures analysed in the northern, and eastern regions of the central Alps. Most interestingly, the weekly temperature anomaly, and the proportion of 'extreme' days, generally decreases as the analyses are extended from 1, 2, 3 and 4 weeks out from each failure. In other words, there is a notable warming, and conditions become increasingly extreme in the lead-up to slope failure. In addition to extreme summer temperatures, our analyses points towards a possible role of unusually warm autumn and spring days influencing slope stability. A linkage between short term periods of extremely warm temperatures and rock failure may be reasonably facilitated through melt water operating within rock discontinues, processes that have recently been measured in high-mountain rock faces, and are considered to be particularly important in spring/early summer melt periods. It is not clear whether slope failures during warm autumn periods can be linked to the same processes. Rockfalls in the winter months remain rare, however, the 27 December 2011 rock avalanche at Piz Cengalo, Val Bregaglia, Switzerland (ca 2-3million m3), occurred following the warmest year on record, potentially reinforcing the role of longer term warming destabilising bedrock with permafrost at depth.

  14. Changes in winter warming events in the Nordic Arctic Region

    NASA Astrophysics Data System (ADS)

    Vikhamar-Schuler, Dagrun; Isaksen, Ketil; Haugen, Jan Erik; Bjerke, Jarle Werner; Tømmervik, Hans

    2015-04-01

    In recent years winter warming events are frequently reported from Arctic areas. Extraordinarily warm weather episodes, occasionally combined with intense rainfall, cause severe ecological disturbance and great challenges for Arctic infrastructure. For example, the formation of ground ice due to winter rain or melting prevents reindeer from grazing, leads to vegetation browning, and impacts soil temperatures. The infrastructure may be affected by avalanches and floods resulting from intense snowmelt. The aim of our analysis is to study changes in warm spells during winter in the Nordic Arctic Region, here defined as the regions in Norway, Sweden and Finland north of the Arctic circle (66.5°N), including the Arctic islands Svalbard and Jan Mayen. Within this study area we have selected the longest available high quality observation series with daily temperature and precipitation. For studying future climate we use available regionally downscaled scenarios. We analyse three time periods: 1) the past 50-100 years, 2) the present (last 15 years, 2000-2014) and 3) the future (next 50-100 years). We define an extended winter season (October-April) and further divide it into three subseasons: 1) Early winter (October and November), 2) Mid-winter (December, January and February) and 3) Late-winter (March and April). We identify warm spells using two different classification criteria: a) days with temperature above 0°C (the melting temperature); and b) days with temperature in excess of the 90th percentile of the 1985-2014 temperature for each subseason. Both wet and dry warm spells are analysed. We compare the results for the mainland stations (maritime and inland stations) with the Arctic islands. All stations have very high frequency of warm weather events in the period 1930-1940s and for the last 15 years (2000-2014). For the most recent period the largest increase in number of warm spells are observed at the northernmost stations. We also find a continuation of this

  15. Changes in Extreme Warm and Cold Temperatures Associated with 20th Century Global Warming

    NASA Astrophysics Data System (ADS)

    Sardeshmukh, P. D.; Compo, G. P.; McColl, C.; Penland, C.

    2015-12-01

    Has 20thcentury global warming resulted in increases of extreme warm temperatures and decreases of extreme cold temperatures around the globe? One would certainly expect this to be so if the changes in the extreme temperature probabilities were determined only by the mean shift and not by changes in the width and/or shape of the temperature distribution. In reality, however, the latter two effects could also be important. Even ignoring changes of shape, it is easily shown that a 25% reduction of standard deviation, for example, can completely offset the effect of a mean positive shift of 0.5 standardized units on the probabilities of extreme positive values. A 25% increase of standard deviation can similarly offset the effect of the mean shift on the probabilities of extreme negative values. It is possible for such changes of standard deviation to occur in regions of large circulation and storminess changes associated with global warming. With this caveat in mind, we have investigated the change in probability of extreme weekly-averaged near-surface air temperatures, in both winter and summer, from the first half-century (1901-1950) to the last half-century (1960-2009) of the 1901 to 2009 period. We have done this using two newly available global atmospheric datasets (ERA-20C and 20CR-v2c) and large ensembles of global coupled climate model simulations of this period, plus very large ensembles of uncoupled atmospheric model simulations of our own. The results are revealing. In the tropics, the changes in the extreme warm and cold temperature probabilities are indeed generally consistent with those expected from the mean shift of the distribution. Outside the tropics, however, they are generally significantly inconsistent with the mean temperature shift, with many regions showing little or no change in the positive temperature extremes and in some instances even a decrease. In such regions, it is clear that the change in the temperature standard deviation is

  16. Passive thermal refugia provided warm water for Florida manatees during the severe winter of 2009-2010

    USGS Publications Warehouse

    Stith, B.M.; Slone, D.H.; de Wit, M.; Edwards, H.H.; Langtimm, C.A.; Swain, E.D.; Soderqvist, L.E.; Reid, J.P.

    2012-01-01

    Haloclines induced by freshwater inflow over tidal water have been identified as an important mechanism for maintaining warm water in passive thermal refugia (PTR) used by Florida manatees Trichechus manatus latirostris during winter in extreme southwestern Florida. Record-setting cold during winter 2009–2010 resulted in an unprecedented number of manatee deaths, adding to concerns that PTR may provide inadequate thermal protection during severe cold periods. Hydrological data from 2009–2010 indicate that 2 canal systems in the Ten Thousand Islands (TTI) region acted as PTR and maintained warm bottom-water temperatures, even during severe and prolonged cold periods. Aerial survey counts of live and dead manatees in TTI during the winter of 2009–2010 suggest that these PTR were effective at preventing mass mortality from hypothermia, in contrast to the nearby Everglades region, which lacks similar artificial PTR and showed high manatee carcass counts. Hydrological data from winter 2008–2009 confirmed earlier findings that without haloclines these artificial PTR may become ineffective as warm-water sites. Tidal pumping of groundwater appears to provide additional heat to bottom water during low tide cycles, but the associated thermal inversion is not observed unless salinity stratification is present. The finding that halocline-driven PTR can maintain warm water even under extreme winter conditions suggests that they may have significant potential as warm-water sites. However, availability and conflicting uses of freshwater and other management issues may make halocline-driven PTR unreliable or difficult to manage during winter.

  17. Increasing climate extremes under global warming - What is the driving force?

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Wang, S. Y.; Gillies, R. R.; Hipps, L.; Kravitz, B.; Rasch, P. J.

    2015-12-01

    More climate extreme events have occurred in recent years, including the continual development of extreme drought in California, the severe cold winters in the eastern U.S. since 2014, 2015 Washington drought, and excessive wildfire events over Alaska in 2015. These have been casually attributed to global warming. However, a need for further understanding of mechanisms responsible for climate extremes is growing. In this presentation, we'll use sets of climate model simulation that designed to identify the role of the oceanic feedback in increasing climate extremes under global warming. One is with a fully coupled climate model forced by 1% ramping CO2, and the other is with an atmosphere only model forced by the same CO2 forcing. By contrasting these two, an importance of the oceanic feedback in increasing climate extremes under global warming can be diagnosed.

  18. The impacts of temperature anomalies and political orientation on perceived winter warming

    NASA Astrophysics Data System (ADS)

    McCright, Aaron M.; Dunlap, Riley E.; Xiao, Chenyang

    2014-12-01

    Although perceptions of common weather phenomena moderately align with instrumental measurements of such phenomena, the evidence that weather or climatic conditions influence beliefs about anthropogenic climate change is mixed. This study addresses both foci, which are important to scholars who investigate human-environment interactions and observers who expect greater exposure to weather or climate extremes to translate into stronger support for climate change adaptive measures and mitigative policies. We analyse the extent to which state-level winter temperature anomalies influence the likelihood of perceiving local winter temperatures to be warmer than usual and attributing these warmer temperatures mainly to global warming. We show that actual temperature anomalies influence perceived warming but not attribution of such warmer-than-usual winter temperatures to global warming. Rather, the latter is influenced more by perceived scientific agreement; beliefs about the current onset, human cause, threat and seriousness of global warming; and political orientation. This is not surprising given the politicization of climate science and political polarization on climate change beliefs in recent years. These results suggest that personal experience with weather or climate variability may help cultivate support for adaptive measures, but it may not increase support for mitigation policies.

  19. Extremely cold events and sudden air temperature drops during winter season in the Czech Republic

    NASA Astrophysics Data System (ADS)

    Crhová, Lenka; Valeriánová, Anna; Holtanová, Eva; Müller, Miloslav; Kašpar, Marek; Stříž, Martin

    2014-05-01

    Today a great attention is turned to analysis of extreme weather events and frequency of their occurrence under changing climate. In most cases, these studies are focused on extremely warm events in summer season. However, extremely low values of air temperature during winter can have serious impacts on many sectors as well (e.g. power engineering, transportation, industry, agriculture, human health). Therefore, in present contribution we focus on extremely and abnormally cold air temperature events in winter season in the Czech Republic. Besides the seasonal extremes of minimum air temperature determined from station data, the standardized data with removed annual cycle are used as well. Distribution of extremely cold events over the season and the temporal evolution of frequency of occurrence during the period 1961-2010 are analyzed. Furthermore, the connection of cold events with extreme sudden temperature drops is studied. The extreme air temperature events and events of extreme sudden temperature drop are assessed using the Weather Extremity Index, which evaluates the extremity (based on return periods) and spatial extent of the meteorological extreme event of interest. The generalized extreme value distribution parameters are used to estimate return periods of daily temperature values. The work has been supported by the grant P209/11/1990 funded by the Czech Science Foundation.

  20. What caused the recent ``Warm Arctic, Cold Continents'' trend pattern in winter temperatures?

    NASA Astrophysics Data System (ADS)

    Sun, Lantao; Perlwitz, Judith; Hoerling, Martin

    2016-05-01

    The emergence of rapid Arctic warming in recent decades has coincided with unusually cold winters over Northern Hemisphere continents. It has been speculated that this "Warm Arctic, Cold Continents" trend pattern is due to sea ice loss. Here we use multiple models to examine whether such a pattern is indeed forced by sea ice loss specifically and by anthropogenic forcing in general. While we show much of Arctic amplification in surface warming to result from sea ice loss, we find that neither sea ice loss nor anthropogenic forcing overall yield trends toward colder continental temperatures. An alternate explanation of the cooling is that it represents a strong articulation of internal atmospheric variability, evidence for which is derived from model data, and physical considerations. Sea ice loss impact on weather variability over the high-latitude continents is found, however, to be characterized by reduced daily temperature variability and fewer cold extremes.

  1. Large stratospheric sudden warming in Antarctic late winter and shallow ozone hole in 1988

    SciTech Connect

    Kanzawa, Hiroshi; Kawaguchi, Sadao )

    1990-01-01

    There occurred a large stratospheric sudden warming in the southern hemisphere in late winter of 1988 which competes in suddenness and size with major mid-winter warmings in the northern hemisphere. Associated with the dynamical phenomenon of the sudden warming, total ozone increased over the eastern hemispheric part of Antarctica. The sudden warming as well as other warmings which followed it made the 1988 Antarctic ozone hole shallow in depth and small in area.

  2. Factors Contributing to Extremely Wet Winters in California

    NASA Astrophysics Data System (ADS)

    Jong, B. T.; Ting, M.; Seager, R.

    2015-12-01

    As California continues to battle the severe drought conditions, it becomes increasingly important to understand the atmospheric and oceanic conditions that may possible break this ongoing drought. Is a strong El Niño, such as the 2015/16 event, enough to break the drought? We examine in this study the possible factors that lead to extremely wet winters (the wettest 15%) in both Northern and Southern CA. The relationships between CA winter precipitation and sea surface temperature conditions in the Pacific, as well as atmospheric circulation are determined by using observational and reanalysis data from 1901 to 2010. One of the key features of the atmospheric circulation is the location of the low pressure anomaly, whether caused by El Niño or other factors. If the anomaly locates right off the US west coast, CA tends to be wet, and vice versa. Furthermore, the duration of the circulation anomaly seems to be crucial. During wet El Niño winters, the peak of the circulation anomaly is in the late winter, whereas, during non-wet El Niño winters, the peak of the anomaly is in the early winter. Thus, an El Niño that can last to late winter is more likely to cause an extremely wet winter in the state. The intensity of El Niño is another critical factor. In the wettest tercile late winter, a strong El Niño can bring about 200% of climatological precipitation to CA, while a weak El Niño can bring only less than 150% of climatology. In combination, only a strong El Niño that can last to late winter may make extremely wet winters very likely in CA. To explore the other factors, composites of circulation anomaly during wet & non-El Niño winters were also analyzed. The results show that a zonally propagating wave train, originating from western North Pacific, contributes to low pressure center and wet winter conditions in the state. Thus, coastal low pressure anomaly is a consistent feature for an extremely wet winters in California, but the origin of forcing can

  3. Mercury concentration in phytoplankton in response to warming of an autumn - winter season.

    PubMed

    Bełdowska, Magdalena; Kobos, Justyna

    2016-08-01

    Among other climate changes in the southern Baltic, there is a tendency towards warming, especially in autumn-winter. As a result, the ice cover on the coastal zone often fails to occur. This is conducive to the thriving of phytoplankton, in which metals, including mercury, can be accumulated. The dry deposition of atmospheric Hg during heating seasons is more intense than in non-heating seasons, owing to the combustion of fossil fuels for heating purposes. This has resulted in studies into the role of phytoplankton in the introduction of Hg into the first link of trophic chain, as a function of autumn and winter warming in the coastal zone of the lagoon. The studies were conducted at two stations in the coastal zone of the southern Baltic, in the Puck Lagoon, between December 2011 and May 2013. The obtained results show that, in the estuary region, the lack of ice cover can lead to a 30% increase and during an "extremely warm" autumn and winter an increase of up to three-fold in the mean annual Hg pool in phytoplankton (mass of Hg in phytoplankton per liter of seawater). The Hg content in phytoplankton was higher when Mesodinium rubrum was prevalent in the biomass, while the proportion of dinoflagellates was small. PMID:27176763

  4. Mercury concentration in phytoplankton in response to warming of an autumn - winter season.

    PubMed

    Bełdowska, Magdalena; Kobos, Justyna

    2016-08-01

    Among other climate changes in the southern Baltic, there is a tendency towards warming, especially in autumn-winter. As a result, the ice cover on the coastal zone often fails to occur. This is conducive to the thriving of phytoplankton, in which metals, including mercury, can be accumulated. The dry deposition of atmospheric Hg during heating seasons is more intense than in non-heating seasons, owing to the combustion of fossil fuels for heating purposes. This has resulted in studies into the role of phytoplankton in the introduction of Hg into the first link of trophic chain, as a function of autumn and winter warming in the coastal zone of the lagoon. The studies were conducted at two stations in the coastal zone of the southern Baltic, in the Puck Lagoon, between December 2011 and May 2013. The obtained results show that, in the estuary region, the lack of ice cover can lead to a 30% increase and during an "extremely warm" autumn and winter an increase of up to three-fold in the mean annual Hg pool in phytoplankton (mass of Hg in phytoplankton per liter of seawater). The Hg content in phytoplankton was higher when Mesodinium rubrum was prevalent in the biomass, while the proportion of dinoflagellates was small.

  5. Warmer and wetter winters: characteristics and implications of an extreme weather event in the High Arctic

    NASA Astrophysics Data System (ADS)

    Hansen, Brage B.; Isaksen, Ketil; Benestad, Rasmus E.; Kohler, Jack; Pedersen, Åshild Ø.; Loe, Leif E.; Coulson, Stephen J.; Larsen, Jan Otto; Varpe, Øystein

    2014-11-01

    One predicted consequence of global warming is an increased frequency of extreme weather events, such as heat waves, droughts, or heavy rainfalls. In parts of the Arctic, extreme warm spells and heavy rain-on-snow (ROS) events in winter are already more frequent. How these weather events impact snow-pack and permafrost characteristics is rarely documented empirically, and the implications for wildlife and society are hence far from understood. Here we characterize and document the effects of an extreme warm spell and ROS event that occurred in High Arctic Svalbard in January-February 2012, during the polar night. In this normally cold semi-desert environment, we recorded above-zero temperatures (up to 7 °C) across the entire archipelago and record-breaking precipitation, with up to 98 mm rainfall in one day (return period of >500 years prior to this event) and 272 mm over the two-week long warm spell. These precipitation amounts are equivalent to 25 and 70% respectively of the mean annual total precipitation. The extreme event caused significant increase in permafrost temperatures down to at least 5 m depth, induced slush avalanches with resultant damage to infrastructure, and left a significant ground-ice cover (˜5-20 cm thick basal ice). The ground-ice not only affected inhabitants by closing roads and airports as well as reducing mobility and thereby tourism income, but it also led to high starvation-induced mortality in all monitored populations of the wild reindeer by blocking access to the winter food source. Based on empirical-statistical downscaling of global climate models run under the moderate RCP4.5 emission scenario, we predict strong future warming with average mid-winter temperatures even approaching 0 °C, suggesting increased frequency of ROS. This will have far-reaching implications for Arctic ecosystems and societies through the changes in snow-pack and permafrost properties.

  6. Recurrent winter warming pulses enhance nitrogen cycling and soil biotic activity in temperate heathland and grassland mesocosms

    NASA Astrophysics Data System (ADS)

    Schuerings, J.; Jentsch, A.; Hammerl, V.; Lenz, K.; Henry, H. A. L.; Malyshev, A. V.; Kreyling, J.

    2014-06-01

    Winter air temperatures are projected to increase in the temperate zone, whereas snow cover is projected to decrease, leading to more extreme soil temperature variability, and potentially to changes in nutrient cycling. Therefore, we applied six winter warming pulses by infra-red heating lamps and surface heating wires in a field experiment over one winter in temperate heathland and grassland mesocosms. The experiment was replicated at two sites, a colder mountainous upland site with high snow accumulation and a warmer and dryer lowland site. Winter warming pulses enhanced soil biotic activity for both sites during winter, as indicated by 35% higher nitrogen (N) availability in the soil solution, 40% higher belowground decomposition and a 25% increase in the activity of the enzyme cellobiohydrolase. The mobilization of N differed between sites, and the incorporation of 15N into leaves was reduced by 31% in response to winter warming pulses, but only at the cold site, with significant reductions occurring for three of four tested plant species at this site. Furthermore, there was a trend of increased N leaching in response to the recurrent winter warming pulses. Overall, projected winter climate change in the temperate zone, with less snow and more variable soil temperatures, appears important for shifts in ecosystem functioning (i.e. nutrient cycling). While the effects of warming pulses on plant N mobilization did not differ among sites, reduced plant 15N incorporation at the colder temperate site suggests that frost damage may reduce plant performance in a warmer world, with important implications for nitrogen cycling and nitrogen losses from ecosystems.

  7. Demographic effects of extreme winter weather in the barn owl.

    PubMed

    Altwegg, Res; Roulin, Alexandre; Kestenholz, Matthias; Jenni, Lukas

    2006-08-01

    Extreme weather events can lead to immediate catastrophic mortality. Due to their rare occurrence, however, the long-term impacts of such events for ecological processes are unclear. We examined the effect of extreme winters on barn owl (Tyto alba) survival and reproduction in Switzerland over a 68-year period (approximately 20 generations). This long-term data set allowed us to compare events that occurred only once in several decades to more frequent events. Winter harshness explained 17 and 49% of the variance in juvenile and adult survival, respectively, and the two harshest winters were associated with major population crashes caused by simultaneous low juvenile and adult survival. These two winters increased the correlation between juvenile and adult survival from 0.63 to 0.69. Overall, survival decreased non-linearly with increasing winter harshness in adults, and linearly in juveniles. In contrast, brood size was not related to the harshness of the preceding winter. Our results thus reveal complex interactions between climate and demography. The relationship between weather and survival observed during regular years is likely to underestimate the importance of climate variation for population dynamics. PMID:16645855

  8. Extreme warm temperatures alter forest phenology and productivity in Europe.

    PubMed

    Crabbe, Richard A; Dash, Jadu; Rodriguez-Galiano, Victor F; Janous, Dalibor; Pavelka, Marian; Marek, Michal V

    2016-09-01

    Recent climate warming has shifted the timing of spring and autumn vegetation phenological events in the temperate and boreal forest ecosystems of Europe. In many areas spring phenological events start earlier and autumn events switch between earlier and later onset. Consequently, the length of growing season in mid and high latitudes of European forest is extended. However, the lagged effects (i.e. the impact of a warm spring or autumn on the subsequent phenological events) on vegetation phenology and productivity are less explored. In this study, we have (1) characterised extreme warm spring and extreme warm autumn events in Europe during 2003-2011, and (2) investigated if direct impact on forest phenology and productivity due to a specific warm event translated to a lagged effect in subsequent phenological events. We found that warmer events in spring occurred extensively in high latitude Europe producing a significant earlier onset of greening (OG) in broadleaf deciduous forest (BLDF) and mixed forest (MF). However, this earlier OG did not show any significant lagged effects on autumnal senescence. Needleleaf evergreen forest (NLEF), BLDF and MF showed a significantly delayed end of senescence (EOS) as a result of extreme warm autumn events; and in the following year's spring phenological events, OG started significantly earlier. Extreme warm spring events directly led to significant (p=0.0189) increases in the productivity of BLDF. In order to have a complete understanding of ecosystems response to warm temperature during key phenological events, particularly autumn events, the lagged effect on the next growing season should be considered. PMID:27152990

  9. Extreme warm temperatures alter forest phenology and productivity in Europe.

    PubMed

    Crabbe, Richard A; Dash, Jadu; Rodriguez-Galiano, Victor F; Janous, Dalibor; Pavelka, Marian; Marek, Michal V

    2016-09-01

    Recent climate warming has shifted the timing of spring and autumn vegetation phenological events in the temperate and boreal forest ecosystems of Europe. In many areas spring phenological events start earlier and autumn events switch between earlier and later onset. Consequently, the length of growing season in mid and high latitudes of European forest is extended. However, the lagged effects (i.e. the impact of a warm spring or autumn on the subsequent phenological events) on vegetation phenology and productivity are less explored. In this study, we have (1) characterised extreme warm spring and extreme warm autumn events in Europe during 2003-2011, and (2) investigated if direct impact on forest phenology and productivity due to a specific warm event translated to a lagged effect in subsequent phenological events. We found that warmer events in spring occurred extensively in high latitude Europe producing a significant earlier onset of greening (OG) in broadleaf deciduous forest (BLDF) and mixed forest (MF). However, this earlier OG did not show any significant lagged effects on autumnal senescence. Needleleaf evergreen forest (NLEF), BLDF and MF showed a significantly delayed end of senescence (EOS) as a result of extreme warm autumn events; and in the following year's spring phenological events, OG started significantly earlier. Extreme warm spring events directly led to significant (p=0.0189) increases in the productivity of BLDF. In order to have a complete understanding of ecosystems response to warm temperature during key phenological events, particularly autumn events, the lagged effect on the next growing season should be considered.

  10. Snow line analysis in the Romanian Carpathians under the influence of winter warming

    NASA Astrophysics Data System (ADS)

    Micu, Dana; Cosmin Sandric, Ionut

    2013-04-01

    The Romanian Carpathians are subject to winter warming as statistically proved by station measurements over a 47 year period (1961-2007). Herein, the snow season is considered to last from the 1st of November to the 30th of April, when snowpack usually reaches the highest stability and thickness. This paper investigates the signals of winter temperature and precipitation change at 17 mountain station located above 1,000 m, as being considered the main triggering factors of large fluctuations in snow amount and duration in these mountains. Fewer snowfalls were recorded all over the Romanian Carpathians after the mid 80s and over large mountain areas (including the alpine ones) the frequency of positive temperature extremes became higher (e.g. winter heat waves). Late Fall snowfalls and snowpack onsets (mainly in mid elevation areas, located below 1,700 m) and particularly the shifts towards early Spring snowmelts (at all the sites) were statistically proved to explain the decline of snow cover duration across the Carpathians. However, the sensitivity of snow cover duration to recent winter warming is still blurred in the high elevation areas (above 2,000 m). The trends in winter climate variability observed in the Romanian Carpathians beyond 1,000 m altitude are fairly comparable to those estimated in other European mountain ranges from observational data (e.g. the Swiss Alps, the French Alps and the Tatra Mts.). In relation to the climate change signals derived from observational data provided by low density mountain meteorological network (of about 3.3 stations per km2 in the areas above 1,000 m), the paper analysis the spatial probability and evolution trends of snow line in each winter season across the Romanian Carpathians, based on Landsat satellite data (MSS, TM and ETM+), with sufficiently high spatial (30 to 60 m) and temporal resolutions (850 images), over the 1973-2011 period. The Landsat coverage was considered suitable enough to enable an objective

  11. The Rapid Arctic Warming in Recent Decade and Its Impact on Eurasia Winter Weather

    NASA Astrophysics Data System (ADS)

    Kim, Seong-Joong; Kim, Baek-Min; Kim, Joo-Hong; Jun, Sang-Yoon

    2016-04-01

    The Arctic is warming much more rapidly than the lower latitudes. In contrast to the rapid Arctic warming, in winters of the recent decade, the cold-air outbreaks over East Asia occur more frequently and stronger than in 1990s. By accompanying the snow over East Asia, the strong cold surges have led to a severe socio-economic impact. Such severe cold surges in recent decade over east Asia is consistent with the more dominant negative phase of the Arctic Oscillation (AO), that may be attributed by the Arctic amplification. In both observation-based reanalysis and numerical model experiments, the Arctic sea ice melting leads to the weakening of the AO polarity by reducing the meridional temperature gradient through a heat flux feedback. The Arctic warming and associated sea ice melting over the Kara-Barents area in late fall and early winter first release a lot of heat to the atmosphere from the ocean by a strong contrast in temperature and moisture and higher height anomaly is developed over the Kara/Barents and the Ural mountains The anomalous anticyclonic anomaly over the Arctic strengthen the Siberian High and at the same time the east Asian trough is developed over the western coast of the North Pacific. Through the passage between the margin of the Siberian High and east Asian tough, an extremely cold air is transported from east Siberia to east Asia for sometimes more than a week. Such a severe sold air brings about the moisture from nearby ocean, largely influencing the daily lives and economy in Eurasia. The recent Arctic and associated sea ice melting is not only contributed to the local climate and weather, but also a severe weather in mid-latitudes through a modulation in polar vortex.

  12. The Rapid Arctic Warming and Its Impact on East Asian Winter Weather in Recent Decade

    NASA Astrophysics Data System (ADS)

    Kim, S. J.; Kim, B. M.; Kim, J. H.

    2015-12-01

    The Arctic is warming much more rapidly than the lower latitudes. In contrast to the rapid Arctic warming, in winters of the recent decade, the cold-air outbreaks over East Asia occur more frequently and stronger than in 1990s. By accompanying the snow over East Asia, the strong cold surges have led to a severe socio-economic impact. Such severe cold surges in recent decade over east Asia is consistent with the more dominant negative phase of the Arctic Oscillation (AO), that may be attributed by the Arctic amplification. In both observation-based reanalysis and numerical model experiments, the Arctic sea ice melting leads to the weakening of the AO polarity by reducing the meridional temperature gradient through a heat flux feedback. The Arctic warming and associated sea ice melting over the Kara-Barents area in late fall and early winter first release a lot of heat to the atmosphere from the ocean by a strong contrast in temperature and moisture and higher height anomaly is developed over the Kara/Barents and the Ural mountains The anomalous anticyclonic anomaly over the Arctic strengthen the Siberian High and at the same time the east Asian trough is developed over the western coast of the North Pacific. Through the passage between the margin of the Siberian High and east Asian tough, an extremely cold air is transported from east Siberia to east Asia for sometimes more than a week. Such a severe sold air brings about the moisture from nearby ocean, largely influencing the daily lives and economy in north East China, Korea, and Japan. The recent Arctic and associated sea ice melting is not only contributed to the local climate and weather, but also a severe weather in mid-latitudes through a modulation in polar vortex.

  13. Persisting cold extremes under 21st-century warming scenarios

    SciTech Connect

    Kodra, Evan A; Steinhaeuser, Karsten J K; Ganguly, Auroop R

    2011-01-01

    Analyses of climate model simulations and observations reveal that extreme cold events are likely to persist across each land-continent even under 21st-century warming scenarios. The grid-based intensity, duration and frequency of cold extreme events are calculated annually through three indices: the coldest annual consecutive three-day average of daily maximum temperature, the annual maximum of consecutive frost days, and the total number of frost days. Nine global climate models forced with a moderate greenhouse-gas emissions scenario compares the indices over 2091 2100 versus 1991 2000. The credibility of model-simulated cold extremes is evaluated through both bias scores relative to reanalysis data in the past and multi-model agreement in the future. The number of times the value of each annual index in 2091 2100 exceeds the decadal average of the corresponding index in 1991 2000 is counted. The results indicate that intensity and duration of grid-based cold extremes, when viewed as a global total, will often be as severe as current typical conditions in many regions, but the corresponding frequency does not show this persistence. While the models agree on the projected persistence of cold extremes in terms of global counts, regionally, inter-model variability and disparity in model performance tends to dominate. Our findings suggest that, despite a general warming trend, regional preparedness for extreme cold events cannot be compromised even towards the end of the century.

  14. Increasing water cycle extremes in California and in relation to ENSO cycle under global warming

    PubMed Central

    Yoon, Jin-Ho; Wang, S-Y Simon; Gillies, Robert R.; Kravitz, Ben; Hipps, Lawrence; Rasch, Philip J.

    2015-01-01

    Since the winter of 2013–2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)—in particular, extreme El Niño and La Niña events that modulate California's climate not only through its warm and cold phases but also its precursor patterns. PMID:26487088

  15. Increasing water cycle extremes in California and in relation to ENSO cycle under global warming.

    PubMed

    Yoon, Jin-Ho; Wang, S-Y Simon; Gillies, Robert R; Kravitz, Ben; Hipps, Lawrence; Rasch, Philip J

    2015-10-21

    Since the winter of 2013-2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)--in particular, extreme El Niño and La Niña events that modulate California's climate not only through its warm and cold phases but also its precursor patterns.

  16. Increasing water cycle extremes in California and in relation to ENSO cycle under global warming.

    PubMed

    Yoon, Jin-Ho; Wang, S-Y Simon; Gillies, Robert R; Kravitz, Ben; Hipps, Lawrence; Rasch, Philip J

    2015-01-01

    Since the winter of 2013-2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)--in particular, extreme El Niño and La Niña events that modulate California's climate not only through its warm and cold phases but also its precursor patterns. PMID:26487088

  17. Increasing water cycle extremes in California and in relation to ENSO cycle under global warming

    NASA Astrophysics Data System (ADS)

    Yoon, Jin-Ho; Wang, S.-Y. Simon; Gillies, Robert R.; Kravitz, Ben; Hipps, Lawrence; Rasch, Philip J.

    2015-10-01

    Since the winter of 2013-2014, California has experienced its most severe drought in recorded history, causing statewide water stress, severe economic loss and an extraordinary increase in wildfires. Identifying the effects of global warming on regional water cycle extremes, such as the ongoing drought in California, remains a challenge. Here we analyse large-ensemble and multi-model simulations that project the future of water cycle extremes in California as well as to understand those associations that pertain to changing climate oscillations under global warming. Both intense drought and excessive flooding are projected to increase by at least 50% towards the end of the twenty-first century; this projected increase in water cycle extremes is associated with a strengthened relation to El Niño and the Southern Oscillation (ENSO)--in particular, extreme El Niño and La Niña events that modulate California's climate not only through its warm and cold phases but also its precursor patterns.

  18. Is the change of winter wheat yield under warming caused by shortened reproductive period?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding the response of winter wheat growth and yield to climate change is essential for projecting grain production in a future warmer world. A field-scale open-warming experiment was conducted to quantify the response of winter wheat growth and yield under conventional tillage (CT) and no-ti...

  19. Change in abundance of pacific brant wintering in alaska: evidence of a climate warming effect?

    USGS Publications Warehouse

    Ward, D.H.; Dau, C.P.; Lee, T.; Sedinger, J.S.; Anderson, B.A.; Hines, J.E.

    2009-01-01

    Winter distribution of Pacific Flyway brant (Branta bernicla nigricans) has shifted northward from lowtemperate areas to sub-Arctic areas over the last 42 years. We assessed the winter abundance and distribution of brant in Alaska to evaluate whether climate warming may be contributing to positive trends in the most northern of the wintering populations. Mean surface air temperatures during winter at the end of the Alaska Peninsula increased about 1??C between 1963 and 2004, resulting in a 23% reduction in freezing degree days and a 34% decline in the number of days when ice cover prevents birds from accessing food resources. Trends in the wintering population fluctuated with states of the Pacific Decadal Oscillation, increasing during positive (warm) phases and decreasing during negative (cold) phases, and this correlation provides support for the hypothesis that growth in the wintering population of brant in Alaska is linked to climate warming. The size of the wintering population was negatively correlated with the number of days of strong northwesterly winds in November, which suggests that the occurrence of tailwinds favorable for migration before the onset of winter was a key factor in whether brant migrated from Alaska or remained there during winter. Winter distribution of brant on the Alaska Peninsula was highly variable and influenced by ice cover, particularly at the heavily used Izembek Lagoon. Observations of previously marked brant indicated that the Alaska wintering population was composed primarily of birds originating from Arctic breeding colonies that appear to be growing. Numbers of brant in Alaska during winter will likely increase as temperatures rise and ice cover decreases at high latitudes in response to climate warming. ?? The Arctic Institute of North America.

  20. The Remarkable 2003-2004 Winter and Other Recent Warm Winters in the Arctic Stratosphere Since the Late 1990s

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Krueger, Kirstin; Sabutis, Joseph L.; Sena, Sara Amina; Pawson, Steven

    2004-01-01

    The 2003-2004 Arctic winter was remarkable in the 40-year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly two months of vortex disruption with high-latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with two previous years, 1984-1985 and 1986-1987, with prolonged mid-winter warming periods shows unique characteristics of the 2003-2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over two standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (seven in the past six years) is unprecedented. Lower stratospheric temperatures were unusually high during six of the past seven years, with five having much lower than usual potential for PSC formation and ozone loss (nearly none in 1998-1999, 2001-2002 and 2003-2004, and very little in 1997-1998 and 2000-2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of five of the last seven years with very low PSC potential would be expected to occur randomly once every approximately 850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.

  1. Shifts in winter distribution in birds: effects of global warming and local habitat change.

    PubMed

    Valiela, Ivan; Bowen, Jennifer L

    2003-11-01

    As global warming intensified toward the end of the 20th century, there was a northward shift in winter ranges of bird species in Cape Cod, Massachusetts, USA. These poleward shifts were correlated to local increases in minimum winter temperatures and global temperature anomalies. This evidence, plus other recent results, suggests that during the last two decades global warming has led to massive and widespread biogeographic shifts with potentially major ecological and human consequences. Local habitat changes associated with urban sprawl affected mainly forest birds with more northern winter distributions. In Cape Cod, the effects of warming on bird distributions are more substantial at the start of the 21st century, than those of habitat alteration, but as urban sprawl continues its importance may rival that of global warming.

  2. Meridional heat transport at the onset of winter stratospheric warming

    NASA Technical Reports Server (NTRS)

    Conte, M.

    1981-01-01

    A continuous vertical flow of energy toward high altitude was verified. This process produced a dynamic instability of the stratospheric polar vortex. A meridional heat transport ws primed toward the north, which generated a warming trend.

  3. The Remarkable 2003--2004 Winter and Other Recent Warm Winters in the Arctic Stratosphere Since the Late 1990s

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Kruger, Kirstin; Sabutis, Joseph L.; Sena, Sara Amina; Pawson, Steven

    2005-01-01

    The 2003-2004 Arctic winter was remarkable in the approximately 50-year record of meteorological analyses. A major warming beginning in early January 2004 led to nearly 2 months of vortex disruption with high-latitude easterlies in the middle to lower stratosphere. The upper stratospheric vortex broke up in late December, but began to recover by early January, and in February and March was the strongest since regular observations began in 1979. The lower stratospheric vortex broke up in late January. Comparison with 2 previous years, 1984-1985 and 1986-1987, with prolonged midwinter warming periods shows unique characteristics of the 2003-2004 warming period: The length of the vortex disruption, the strong and rapid recovery in the upper stratosphere, and the slow progression of the warming from upper to lower stratosphere. January 2004 zonal mean winds in the middle and lower stratosphere were over 2 standard deviations below average. Examination of past variability shows that the recent frequency of major stratospheric warmings (7 in the past 6 years) is unprecedented. Lower stratospheric temperatures were unusually high during 6 of the past 7 years, with 5 having much lower than usual potential for polar stratospheric cloud (PSC) formation and ozone loss (nearly none in 1998-1999, 2001-2002, and 2003-2004, and very little in 1997-1998 and 2000-2001). Middle and upper stratospheric temperatures, however, were unusually low during and after February. The pattern of 5 of the last 7 years with very low PSC potential would be expected to occur randomly once every 850 years. This cluster of warm winters, immediately following a period of unusually cold winters, may have important implications for possible changes in interannual variability and for determination and attribution of trends in stratospheric temperatures and ozone.

  4. Analysis of extreme summers and prior late winter/spring conditions in central Europe

    NASA Astrophysics Data System (ADS)

    Träger-Chatterjee, C.; Müller, R. W.; Bendix, J.

    2013-05-01

    Drought and heat waves during summer in mid-latitudes are a serious threat to human health and agriculture and have negative impacts on the infrastructure, such as problems in energy supply. The appearance of such extreme events is expected to increase with the progress of global warming. A better understanding of the development of extremely hot and dry summers and the identification of possible precursors could help improve existing seasonal forecasts in this regard, and could possibly lead to the development of early warning methods. The development of extremely hot and dry summer seasons in central Europe is attributed to a combined effect of the dominance of anticyclonic weather regimes and soil moisture-atmosphere interactions. The atmospheric circulation largely determines the amount of solar irradiation and the amount of precipitation in an area. These two variables are themselves major factors controlling the soil moisture. Thus, solar irradiation and precipitation are used as proxies to analyse extreme sunny and dry late winter/spring and summer seasons for the period 1958-2011 in Germany and adjacent areas. For this purpose, solar irradiation data from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis dataset, as well as remote sensing data are used. Precipitation data are taken from the Global Precipitation Climatology Project. To analyse the atmospheric circulation geopotential data at 850 hPa are also taken from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis datasets. For the years in which extreme summers in terms of high solar irradiation and low precipitation are identified, the previous late winter/spring conditions of solar irradiation and precipitation in Germany and adjacent areas are analysed. Results show that if the El Niño-Southern Oscillation (ENSO) is not very intensely developed, extremely high solar irradiation amounts, together with extremely low precipitation

  5. Extreme Winter/Early-Spring Temperature Anomalies in Central Europe

    NASA Technical Reports Server (NTRS)

    Otterman, Joseph; Atlas, Robert; Ardizzone, Joseph; Brakke, Thomas; Chou, Shu-Hsien; Jusem, Juan Carlos; Glantz, Michael; Rogers, Jeff; Sud, Yogesh; Susskind, Joel

    2000-01-01

    Extreme seasonal fluctuations of the surface-air temperature characterize the climate of central Europe, 45-60 deg North Temperature difference between warm 1990 and cold 1996 in the January-March period, persisting for more than two weeks at a time, amounted to 18 C for extensive areas. These anomalies in the surface-air temperature stem in the first place from differences in the low level flow from the eastern North-Atlantic: the value of the Index 1na of southwesterlies over the eastern North-Atlantic was 8.0 m/s in February 1990, but only 2.6 m/ s in February 1996. The primary forcing by warm advection to positive anomalies in monthly mean surface temperature produced strong synoptic-scale uplift at the 700 mb level over some regions in Europe. The strong uplift contributed in 1990 to a much larger cloud-cover over central Europe, which reduced heat-loss to space (greenhouse effect). Thus, spring arrived earlier than usual in 1990, but later than usual in 1996.

  6. Extreme Precipitation Events in Saudi Arabia: Tropical-Extratropical Interactions in Autumn, Winter and Spring

    NASA Astrophysics Data System (ADS)

    De Vries, Andries Jan; Feldstein, Steven B.; Fnais, Mohammed; Tyrlis, Evangelos; Lelieveld, Jos

    2014-05-01

    The Middle East has a very dry climate, however, at times, extreme rainfall can cause flash floods with severe societal impacts. Using reanalysis (ERA-Interim) and observational precipitation (TRMM 3B42 and station) data, we study the underlying synoptic-scale atmospheric dynamics of three extreme precipitation events in Saudi Arabia occurring in autumn, winter and spring. All three cases involve strong tropical-extratropical interactions. A midlatitude upper level trough, associated with Rossby wave breaking, intrudes into the subtropics and interacts with the (sub)tropical low level circulation, which triggers intensive poleward transport of tropical moisture and strong upward motions. The autumn case (November 2009) shows enhanced moisture transport over the Arabian and Red Seas together with the northward extension of the Red Sea trough, i.e. being an "Active Red Sea Trough" event. The winter case (January 2005) has characteristics of a tropical plume and involves the coupling of an equatorward penetrating cyclonic disturbance and the tropical low pressure zone over Equatorial Africa, significant moisture transport over central Africa and an intensified subtropical jet stream. The spring case (April-May 2013) demonstrates a prolonged period of intense convective activity, promoted by strong surface heating, a quasi-stationary upper level trough and associated cold air, and a persistent low level warm and moist air flow, partly originating from the southern hemispheric Indian Ocean through a cross-equatorial surge. The three events are strongly influenced by the seasonality of the climatological large-scale circulation.

  7. Increasing water cycle extremes in California and relation to ENSO cycle under global warming

    SciTech Connect

    Yoon, Jin -Ho; Wang, S. -Y. Simon; Gillies, Robert R.; Kravitz, Benjamin S.; Hipps, Lawrence; Rasch, Philip J.

    2015-10-21

    California has experienced its most severe drought in recorded history since the winter of 2013-2014. The long duration of drought has stressed statewide water resources and the economy, while fueling an extraordinary increase in wildfires. The effects of global warming on the regional climate include a hotter and drier climate, as well as earlier snowmelt, both of which exacerbate drought conditions. However, connections between a changing climate and how climate oscillations modulate regional water cycle extremes are not well understood. Here we analyze large-ensemble simulations of future climate change in California using the Community Earth System Model version 1 (CESM1) and multiple climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Both intense drought and excessive flooding are projected to increase by at least 50% toward the end of the 21st century. Furthermore, the projected increase in water cycle extremes is associated with tighter relation to El Niño and Southern Oscillation (ENSO), particularly extreme El Niño and La Niña events, which modulates California’s climate not only through its warm and cold phases, but also ENSO’s precursor patterns.

  8. Increasing water cycle extremes in California and relation to ENSO cycle under global warming

    DOE PAGES

    Yoon, Jin -Ho; Wang, S. -Y. Simon; Gillies, Robert R.; Kravitz, Benjamin S.; Hipps, Lawrence; Rasch, Philip J.

    2015-10-21

    California has experienced its most severe drought in recorded history since the winter of 2013-2014. The long duration of drought has stressed statewide water resources and the economy, while fueling an extraordinary increase in wildfires. The effects of global warming on the regional climate include a hotter and drier climate, as well as earlier snowmelt, both of which exacerbate drought conditions. However, connections between a changing climate and how climate oscillations modulate regional water cycle extremes are not well understood. Here we analyze large-ensemble simulations of future climate change in California using the Community Earth System Model version 1 (CESM1)more » and multiple climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Both intense drought and excessive flooding are projected to increase by at least 50% toward the end of the 21st century. Furthermore, the projected increase in water cycle extremes is associated with tighter relation to El Niño and Southern Oscillation (ENSO), particularly extreme El Niño and La Niña events, which modulates California’s climate not only through its warm and cold phases, but also ENSO’s precursor patterns.« less

  9. ON THE INSTABILITY OF TROPICAL WESTERN PACIFIC WARM POOL DURING THE BOREAL WINTER AND SPRING

    SciTech Connect

    BARR-KUMARAKULASINGHE,S.A.

    1998-03-23

    A source of instability in the western Pacific warm pool is shown to be due to sea surface elevation variations caused by changes in the zonal sea-surface temperature (SST) gradient and the changes in the Pacific Ocean basin length in relation to the warm pool latitudinal location. The variation of the sea-surface elevation is measured by using the thermocline depth response calculated from a two-layer ocean. The warm pool is shown to be barely at equilibrium during the boreal late winter and early spring by comparing the measured thermocline at 110{degree}W, 0{degree}E with the calculated thermocline depth. Based on this analysis, a failure or reversal of the climatological zonal winds are apparently not a necessary precursor for the instability of the warm pool and initiation of a warm event. A warm event can be initiated by an increase in the size of the warm pool and/or an increase in zonal SST differences during the boreal/winter spring. This mechanism could be an alternate mechanism for El-Nino Southern Oscillation (ENSO) dynamics to that postulated by Bjeknes (1969).

  10. [Effects of nighttime warming on winter wheat root growth and soil nutrient availability].

    PubMed

    Zhang, Ming-Qian; Chen, Jin; Guo, Jia; Tian, Yun-Lu; Yang, Shi-Jia; Zhang, Li; Yang, Bing; Zhang, Wei-Jian

    2013-02-01

    Climate warming has an obvious asymmetry between day and night, with a greater increment of air temperature at nighttime than at daytime. By adopting passive nighttime warming (PNW) system, a two-year field experiment of nighttime warming was conducted in the main production areas of winter wheat in China (Shijiazhuang of Hebei Province, Xuzhou of Jiangsu Province, Xuchang of Henan Province, and Zhenjiang of Jiangsu Province) in 2009 and 2010, with the responses of soil pH and available nutrient contents during the whole growth periods and of wheat root characteristics at heading stage determined. As compared with the control (no nighttime warming), nighttime warming decreased the soil pH and available nutrient contents significantly, and increased the root dry mass and root/shoot ratio to a certain extent. During the whole growth period of winter wheat, nighttime warming decreased the soil pH in Shijiazhuang, Xuzhou, Xuchang, and Zhenjiang averagely by 0.4%, 0.4%, 0.7%, and 0.9%, the soil alkaline nitrogen content averagely by 8.1%, 8.1%, 7.1%, and 6.0%, the soil available phosphorus content averagely by 15.7%, 12.1%, 19.6%, and 25.8%, and the soil available potassium content averagely by 11.5%, 7.6%, 7.6% , and 10.1%, respectively. However, nighttime warming increased the wheat root dry mass at heading stage in Shijiazhuang, Xuzhou, and Zhenjiang averagely by 31. 5% , 27.0%, and 14.5%, and the root/shoot ratio at heading stage in Shijiazhuang, Xuchang, and Zhenjiang averagely by 23.8%, 13.7% and 9.7%, respectively. Our results indicated that nighttime warming could affect the soil nutrient supply and winter wheat growth via affecting the soil chemical properties. PMID:23705390

  11. [Effects of nighttime warming on winter wheat root growth and soil nutrient availability].

    PubMed

    Zhang, Ming-Qian; Chen, Jin; Guo, Jia; Tian, Yun-Lu; Yang, Shi-Jia; Zhang, Li; Yang, Bing; Zhang, Wei-Jian

    2013-02-01

    Climate warming has an obvious asymmetry between day and night, with a greater increment of air temperature at nighttime than at daytime. By adopting passive nighttime warming (PNW) system, a two-year field experiment of nighttime warming was conducted in the main production areas of winter wheat in China (Shijiazhuang of Hebei Province, Xuzhou of Jiangsu Province, Xuchang of Henan Province, and Zhenjiang of Jiangsu Province) in 2009 and 2010, with the responses of soil pH and available nutrient contents during the whole growth periods and of wheat root characteristics at heading stage determined. As compared with the control (no nighttime warming), nighttime warming decreased the soil pH and available nutrient contents significantly, and increased the root dry mass and root/shoot ratio to a certain extent. During the whole growth period of winter wheat, nighttime warming decreased the soil pH in Shijiazhuang, Xuzhou, Xuchang, and Zhenjiang averagely by 0.4%, 0.4%, 0.7%, and 0.9%, the soil alkaline nitrogen content averagely by 8.1%, 8.1%, 7.1%, and 6.0%, the soil available phosphorus content averagely by 15.7%, 12.1%, 19.6%, and 25.8%, and the soil available potassium content averagely by 11.5%, 7.6%, 7.6% , and 10.1%, respectively. However, nighttime warming increased the wheat root dry mass at heading stage in Shijiazhuang, Xuzhou, and Zhenjiang averagely by 31. 5% , 27.0%, and 14.5%, and the root/shoot ratio at heading stage in Shijiazhuang, Xuchang, and Zhenjiang averagely by 23.8%, 13.7% and 9.7%, respectively. Our results indicated that nighttime warming could affect the soil nutrient supply and winter wheat growth via affecting the soil chemical properties.

  12. Impact of global warming on the Asian winter monsoon in a coupled GCM

    NASA Astrophysics Data System (ADS)

    Hu, Zeng-Zhen; Bengtsson, Lennart; Arpe, Klaus

    2000-02-01

    The Asian winter monsoon (AWM) response to the global warming was investigated through a long-term integration of the transient greenhouse warming with the ECHAM4/OPYC3 CGCM. The physics of the response was studied through analyses of the impact of the global warming on the variations of the ocean and land contrast near the ground in the Asian and western Pacific region and the east Asian trough and jet stream in the middle and upper troposphere. Forcing of transient eddy activity on the zonal circulation over the Asian and western Pacific region was also analyzed. It is found that in the global warming scenario the winter northeasterlies along the Pacific coast of the Eurasian continent weaken systematically and significantly, and intensity of the AWM reduces evidently, but the AWM variances on the interannual and interdecadal scales are not affected much by the global warming. It is suggested that the global warming makes the climate over the most part of Asia to be milder with enhanced moisture in winter. In the global warming scenario the contrasts of the sea level pressure and the near-surface temperature between the Asian continent and the Pacific Ocean become significantly smaller, northward and eastward shifts and weakening of the east Asian trough and jet stream in the middle and upper troposphere are found. As a consequence, the cold air in the AWM originating from the east Asian trough and high latitudes is less powerful. In addition, feedback of the transient activity also makes a considerable contribution to the higher-latitude shift of the jet stream over the North Pacific in the global warming scenario.

  13. The role of the tropical West Pacific in the extreme northern hemisphere winter of 2013/14

    NASA Astrophysics Data System (ADS)

    Watson, Peter; Weisheimer, Antje; Knight, Jeff; Palmer, Tim

    2016-04-01

    In the 2013/14 winter, the eastern USA was exceptionally cold, the Bering Strait region was exceptionally warm, California was in the midst of drought and the UK suffered severe flooding. It has been suggested that elevated SSTs in the tropical West Pacific (TWPAC) were partly to blame due to their producing a Rossby wavetrain that propagated into the extratropics. We find that seasonal forecasts with the tropical atmosphere relaxed towards a reanalysis give 2013/14 winter-mean anomalies with strong similarities to those observed in the Northern Hemisphere, indicating that low-latitude anomalies had a role in the development of the extremes. Relaxing just the TWPAC produces a strong wavetrain over the North Pacific and North America in January, but not in the winter-mean. This suggests that anomalies in this region alone had a large influence, but cannot explain the extremes through the whole winter. We also examine the response to applying the observed TWPAC SST anomalies in two atmospheric general circulation models. We find that this does produce winter-mean anomalies in the North Pacific and North America resembling those observed, but that the tropical forcing of Rossby waves due to the applied SST anomalies appears stronger than that in reanalysis, except in January. Therefore both experiments indicate that the TWPAC influence was important, but the true strength of the TWPAC influence is uncertain. None of the experiments indicate a strong systematic impact of the TWPAC anomalies on Europe.

  14. The role of the tropical West Pacific in the extreme Northern Hemisphere winter of 2013/2014

    NASA Astrophysics Data System (ADS)

    Watson, Peter A. G.; Weisheimer, Antje; Knight, Jeff R.; Palmer, T. N.

    2016-02-01

    In the 2013/2014 winter, the eastern U.S. was exceptionally cold, the Bering Strait region was exceptionally warm, California was in the midst of drought, and the UK suffered severe flooding. It has been suggested that elevated sea surface temperatures (SSTs) in the tropical West Pacific (TWPAC) were partly to blame due to them producing a Rossby wave train that propagated into the extratropics. We find that seasonal forecasts with the tropical atmosphere relaxed toward a reanalysis give 2013/2014 winter mean anomalies with strong similarities to those observed in the Northern Hemisphere, indicating that low-latitude anomalies had a role in the development of the extremes. Relaxing just the TWPAC produces a strong wave train over the North Pacific and North America in January, but not in the winter mean. This suggests that anomalies in this region alone had a large influence but cannot explain the extremes through the whole winter. We also examine the response to applying the observed TWPAC SST anomalies in two atmospheric general circulation models. We find that this does produce winter mean anomalies in the North Pacific and North America resembling those observed and that the tropical forcing of Rossby waves due to the applied SST anomalies appears stronger than that in reanalysis, except in January. Therefore, both experiments indicate that the TWPAC influence was important, but the true strength of the TWPAC influence is uncertain. None of the experiments indicate a strong systematic impact of the TWPAC anomalies on Europe.

  15. A method to measure winter precipitation and sublimation under global warming conditions

    NASA Astrophysics Data System (ADS)

    Herndl, Markus; Slawitsch, Veronika; von Unold, Georg

    2016-04-01

    Winter precipitation and snow sublimation are fundamental components of the alpine moisture budget. Much work has been done in the study of these processes and its important contribution to the annual water balance. Due to the above-average sensitivity of the alpine region to climate change, a change in the importance and magnitude of these water balance parameters can be expected. To determine these effects, a lysimeter-facility enclosed in an open-field climate manipulation experiment was established in 2015 at AREC Raumberg-Gumpenstein which is able to measure winter precipitation and sublimation under global warming conditions. In this facility, six monolithic lysimeters are equipped with a snow cover monitoring system, which separates the snow cover above the lysimeter automatically from the surrounding snow cover. Three of those lysimeters were exposed to a +3°C scenario and three lysimeters to ambient conditions. Weight data are recorded every minute and therefore it is possible to get high-resolution information about the water balance parameter in winter. First results over two snow event periods showed that the system can measure very accurately winter precipitation and sublimation especially in comparison with other measurement systems and usually used models. Also first trends confirm that higher winter temperatures may affect snow water equivalent and snow cover duration. With more data during the next years using this method, it is possible to quantify the influence of global warming on water balance parameters during the winter periods.

  16. Extreme temperature contrast of the year 2012 in Greece: An exceptionally cold winter and a record breaking summer

    NASA Astrophysics Data System (ADS)

    Tolika, Konstantia; Anagnostopoulou, Christina; Maheras, Panagiotis; Velikou, Kondylia

    2013-04-01

    During the past decade several regions all over Europe have experienced severe heat waves with serious social and environmental impacts. The year of 2003 was characterized by record breaking high temperatures for central Europe, while the year of 2007 was a remarkably warm year of the majority of the Eastern Mediterranean. During this year, three major heat waves were detected in Greece during summer and abnormally high temperatures were also observed through the cold season of 2007. It was found that the winter minimum temperatures were statistically more extreme than the summer maxima. Moreover, exceptionally high maximum and minimum temperatures occurred in November of 2010 affection the entire Greek region while September of the following year was also characterized by large departures of maximum temperatures from the long term mean values and the highest minimum temperature average in comparison to the reference period 1958-2000. The past year (2012) could also be characterized as a year of extremes. This time a temperature contrast was detected in the domain of study with a prolonged cold - season spell during winter and new record - breaking extreme maximum and minimum summer temperatures. More specifically it was found that the summer of 2012 was the warmest one since 1958. The whole season was characterized by long - lasting warm conditions with large departures from the long term (up to 4oC for Tmax) and this warming phenomenon was more intense during July and August. In contrast the winter season (December 2011 - February 2012) was found to be in the ten coldest winters of the last 55 years. The departures from the mean are lower than summer (1oC to 1.5oC negative anomalies) but most of the days were found to have lower Tmax, Tmin and Tmean values than the average daily temperatures of the period 1958-2000. Finally, it is worth mentioning that the year of 2012 was characterized by the highest annual temperature range reaching up to 26oC in several

  17. Climatic warming increases winter wheat yield but reduces grain nitrogen concentration in east China.

    PubMed

    Tian, Yunlu; Zheng, Chengyan; Chen, Jin; Chen, Changqing; Deng, Aixing; Song, Zhenwei; Zhang, Baoming; Zhang, Weijian

    2014-01-01

    Climatic warming is often predicted to reduce wheat yield and grain quality in China. However, direct evidence is still lacking. We conducted a three-year experiment with a Free Air Temperature Increase (FATI) facility to examine the responses of winter wheat growth and plant N accumulation to a moderate temperature increase of 1.5°C predicted to prevail by 2050 in East China. Three warming treatments (AW: all-day warming; DW: daytime warming; NW: nighttime warming) were applied for an entire growth period. Consistent warming effects on wheat plant were recorded across the experimental years. An increase of ca. 1.5°C in daily, daytime and nighttime mean temperatures shortened the length of pre-anthesis period averagely by 12.7, 8.3 and 10.7 d (P<0.05), respectively, but had no significant impact on the length of the post-anthesis period. Warming did not significantly alter the aboveground biomass production, but the grain yield was 16.3, 18.1 and 19.6% (P<0.05) higher in the AW, DW and NW plots than the non-warmed plot, respectively. Warming also significantly increased plant N uptake and total biomass N accumulation. However, warming significantly reduced grain N concentrations while increased N concentrations in the leaves and stems. Together, our results demonstrate differential impacts of warming on the depositions of grain starch and protein, highlighting the needs to further understand the mechanisms that underlie warming impacts on plant C and N metabolism in wheat.

  18. Climatic Warming Increases Winter Wheat Yield but Reduces Grain Nitrogen Concentration in East China

    PubMed Central

    Deng, Aixing; Song, Zhenwei; Zhang, Baoming; Zhang, Weijian

    2014-01-01

    Climatic warming is often predicted to reduce wheat yield and grain quality in China. However, direct evidence is still lacking. We conducted a three-year experiment with a Free Air Temperature Increase (FATI) facility to examine the responses of winter wheat growth and plant N accumulation to a moderate temperature increase of 1.5°C predicted to prevail by 2050 in East China. Three warming treatments (AW: all-day warming; DW: daytime warming; NW: nighttime warming) were applied for an entire growth period. Consistent warming effects on wheat plant were recorded across the experimental years. An increase of ca. 1.5°C in daily, daytime and nighttime mean temperatures shortened the length of pre-anthesis period averagely by 12.7, 8.3 and 10.7 d (P<0.05), respectively, but had no significant impact on the length of the post-anthesis period. Warming did not significantly alter the aboveground biomass production, but the grain yield was 16.3, 18.1 and 19.6% (P<0.05) higher in the AW, DW and NW plots than the non-warmed plot, respectively. Warming also significantly increased plant N uptake and total biomass N accumulation. However, warming significantly reduced grain N concentrations while increased N concentrations in the leaves and stems. Together, our results demonstrate differential impacts of warming on the depositions of grain starch and protein, highlighting the needs to further understand the mechanisms that underlie warming impacts on plant C and N metabolism in wheat. PMID:24736557

  19. Extreme Winter Cyclones in the North Atlantic in a CESM1.0.1 Last Millennium Climate Simulation

    NASA Astrophysics Data System (ADS)

    Blumer, Sandro R.; Raible, Christoph C.; Lehner, Flavio; Stocker, Thomas F.

    2015-04-01

    Extreme cyclones and their associated impacts are a major threat to mankind, as they often result in heavy precipitation events and severe winds. The last millennium is closest to the Anthropocene and has the best coverage of paleoclimatic information. Therefore, it could serve as a test bed for estimating natural forcing variations beyond the recent observational period and could deliver insights into the frequency and intensity of extreme events, including strong cyclones and their dependency on internal variability and external forcing. The aim of this study is to investigate how the frequency and intensity of extreme cyclones in the North Atlantic have changed in the last millennium, in particular during prolonged cold and warm periods and which changes might be expected for the 21st century. We use a comprehensive fully-coupled transient climate simulation of the last millennium (AD 1000-2100) with a relatively high spatial (0.9x1.25 degrees) resolution and define six climatic periods according to prolonged cold or warm phases: Medieval Climate Anomaly (MCA), AD 1150-1200, Little Ice Age (LIA), AD 1450-1500, Maunder Minimum (MMI), AD 1645-1720, Historical (HIS), AD 1850-2005, Modern (MOD), 1960-2010 and Projection (PRO), AD 2006-2099. Cyclones are then detected and tracked in 12-hourly output using an algorithm that is based on the geopotential height field on 1000 hPa. Additionally, two intensity criteria for extreme cyclones are defined: the 90 percentile of the mean gradient in geopotential and the 90 percentile of the precipitation within a radius of 500 km around the cyclone centre at every time step during the lifetime of a cyclone. These criteria consider two aspects of cyclone's intensity: extremes in wind and precipitation. The results show that extremes of North Atlantic winter cyclone intensity are significantly stronger with respect to the geopotential height gradient during prolonged cold periods and weaker during prolonged warm periods

  20. Extreme winter cyclones and the extinction of a reindeer population (Invited)

    NASA Astrophysics Data System (ADS)

    Walsh, J. E.; Klein, D. R.; Shulski, M.

    2009-12-01

    While strong cyclones are not unusual are not unusual in the subpolar North Pacific storm track, an exceptional series of storm events in early 1964 decimated the reindeer population of St. Matthew Island in the central Bering Sea. This case illustrates how severe winter storms can lead to species extinction when overpopulated species are restricted to islands or fractured habitats where dispersal is not an option. The strongest storm occurred in early February when a surface low pressure system that originated over the warm waters offshore of Japan tracked eastward from the warm waters offshore of Japan. The intensification of the low then accelerated as the storm approached the Aleutians, where the central pressure decreased to 957 hPa, a pressure typical of Category 3 hurricanes. The track and intensity of the low were such that St. Matthew Island was in the storm’s northwest quadrant during the peak-intensity phase. The pressure difference between the intense cyclone and the Siberian high exceeded 100 hPa -- a pressure difference between these two locations that was the largest in the entire 60-year period of the NCEP reanalysis. This record pressure difference led to extremely strong northerly winds that brought bitterly cold arctic air over St. Matthew Island, which was in the storm’s northwest quadrant. The wind chill temperature dropped to -50°C and remained colder than -40°C almost continuously for a full week. In this presentation, we examine the storm’s evolution and place the winter of early 1964 into the context of the historical cyclone climatological of the North Pacific.

  1. Windowpane flounder (Scophthalmus aquosus) and winter flounder (Pseudopleuronectes americanus) responses to cold temperature extremes in a Northwest Atlantic estuary

    NASA Astrophysics Data System (ADS)

    Wilber, Dara H.; Clarke, Douglas G.; Alcoba, Catherine M.; Gallo, Jenine

    2016-01-01

    The effect of climate variability on flatfish includes not only the effects of warming on sensitive life history stages, but also impacts from more frequent or unseasonal extreme cold temperatures. Cold weather events can affect the overwintering capabilities of flatfish near their low temperature range limits. We examined the responses of two flatfish species, the thin-bodied windowpane (Scophthalmus aquosus) and cold-tolerant winter flounder (Pseudopleuronectes americanus), to variable winter temperatures in a Northwest Atlantic estuary using abundance and size data collected during a monitoring study, the Aquatic Biological Survey, conducted from 2002 to 2010. Winter and spring abundances of small (50 to 120 mm total length) juvenile windowpane were positively correlated with adult densities (spawning stock) and fall temperatures (thermal conditions experienced during post-settlement development for the fall-spawned cohort) of the previous year. Windowpane abundances in the estuary were significantly reduced and the smallest size class was nearly absent after several consecutive years with cold (minimum temperatures < 1 °C) winters. Interannual variation in winter flounder abundances was unrelated to the severity of winter temperatures. A Paulik diagram illustrates strong positive correlations between annual abundances of sequential winter flounder life history stages (egg, larval, Age-1 juvenile, and adult male) within the estuary, reflecting residency within the estuary through their first year of life. Temperature variables representing conditions during winter flounder larval and post-settlement development were not significant factors in multiple regression models exploring factors that affect juvenile abundances. Likewise, densities of predators known to consume winter flounder eggs and/or post-settlement juveniles were not significantly related to interannual variation in winter flounder juvenile abundances. Colder estuarine temperatures through the

  2. No snow for Christmas: the impact of the 2015 extreme winter on CO2 fluxes in European mountain grasslands

    NASA Astrophysics Data System (ADS)

    Cremonese, Edoardo; Galvagno, Marta; Hammerle, Albin; Filippa, Gianluca; Wohlfahrt, Georg

    2016-04-01

    The increasing frequency in extreme climate events is very likely to impact the Alps since this region is characterized by very sensitive ecosystems. Typical alpine ecosystems such as mountain grasslands, show a strong seasonality in carbon uptake and release mostly driven by the onset and the end of the snow season. Extreme climate events, such as long warm and/or dry periods, could change typical snow cover temporal pattern, thereby altering the duration of the period of CO2 uptake and release. In recent years many studies have analyzed the impact of delayed or anticipated snowmelt on alpine plant phenology, growth and carbon cycling. However, little is known on the effects of a delayed onset of the snow season. During 2015 the whole planet witnessed several record-breaking warm spells which exceptionally warmed the Alps where the temperature anomaly reached +4°C during both the autumn and winter periods. In particular, the onset of the 2015 winter in the Alps was marked by one of the most prolonged lack of snow in years. In this study, we investigate and discuss the impact of the altered temperature and precipitation pattern during the autumn/winter 2015 on the net ecosystem CO2 exchange of mountain grasslands at high and low altitudes measured by means of the eddy covariance method. In particular we test the following hypotheses: (i) The presence of a snowpack impedes plant photosynthesis, while without a snowpack, plant net CO2 uptake may be possible even during wintertime provided temperatures are warm enough. (ii) Below a snowpack, soil temperatures are around zero degrees Celsius, allowing for microbial activity resulting in intermediate soil respiration; without a snow cover soil temperatures may be either lower or higher than zero degrees Celsius, decreasing or increasing soil respiration. The magnitude and direction of the net ecosystem CO2 exchange of mountain grassland ecosystems is governed by the complex interplay of the factors addressed in

  3. [Effects of Reduced Water and Diurnal Warming on Winter-Wheat Biomass and Soil Respiration].

    PubMed

    Wu, Yang-zhou; Chen, Jian; Hu, Zheng-hua; Xie, Yan; Chen, Shu-tao; Zhang, Xue-song; Shen, Shuang-he; Chen, Xi

    2016-01-15

    Field experiments were conducted in winter wheat-growing season to investigate the effect of reduced water and diurnal warming on wheat biomass and soil respiration. The experimental treatments included the control (CK), 30% reduced water (W), diurnal warming (T, enhanced 2 degrees C), and the combined treatment (TW, 30% reduced water plus diurnal warming 2 degrees C). Soil respiration rate was measured using a static chamber-gas chromatograph technique. The results showed that in the winter wheat-growing season, compared to CK, T and TW treatments significantly increased shoot biomass by 46.0% (P = 0.002) and 19.8% (P = 0.032) during the elongation-booting stage, respectively. T and TW treatments also significantly increased the harvested shoot biomass by 19.8% (P = 0.050) and 34.6% (P = 0.028), respectively. On the other hand, W treatment had no significant effect on shoot biomass, and W, T, and TW treatments didn't significantly change the root biomass. T and W treatments had no significant effect on the mean respiration rate (MRR) of soil (P > 0.05). TW treatment significantly decreased soil MRR by 22.4% (P = 0.049). We also found T treatment decreased the temperature sensitivity coefficients of soil respiration (Q10). The results of our study suggested that compared to the single treatment (reduced water or diurnal warming), the combined treatment (reduced water plus diurnal warming) may have different effects on agroecosystem.

  4. [Effects of Reduced Water and Diurnal Warming on Winter-Wheat Biomass and Soil Respiration].

    PubMed

    Wu, Yang-zhou; Chen, Jian; Hu, Zheng-hua; Xie, Yan; Chen, Shu-tao; Zhang, Xue-song; Shen, Shuang-he; Chen, Xi

    2016-01-15

    Field experiments were conducted in winter wheat-growing season to investigate the effect of reduced water and diurnal warming on wheat biomass and soil respiration. The experimental treatments included the control (CK), 30% reduced water (W), diurnal warming (T, enhanced 2 degrees C), and the combined treatment (TW, 30% reduced water plus diurnal warming 2 degrees C). Soil respiration rate was measured using a static chamber-gas chromatograph technique. The results showed that in the winter wheat-growing season, compared to CK, T and TW treatments significantly increased shoot biomass by 46.0% (P = 0.002) and 19.8% (P = 0.032) during the elongation-booting stage, respectively. T and TW treatments also significantly increased the harvested shoot biomass by 19.8% (P = 0.050) and 34.6% (P = 0.028), respectively. On the other hand, W treatment had no significant effect on shoot biomass, and W, T, and TW treatments didn't significantly change the root biomass. T and W treatments had no significant effect on the mean respiration rate (MRR) of soil (P > 0.05). TW treatment significantly decreased soil MRR by 22.4% (P = 0.049). We also found T treatment decreased the temperature sensitivity coefficients of soil respiration (Q10). The results of our study suggested that compared to the single treatment (reduced water or diurnal warming), the combined treatment (reduced water plus diurnal warming) may have different effects on agroecosystem. PMID:27078968

  5. Notes and Correspondence: The effect of enhanced greenhouse warming on winter cyclone frequencies and strengths

    SciTech Connect

    Lambert, S.J.

    1995-05-01

    The extratropical winter cyclone climatologies for the Northern and Southern Hemispheres are presented for a control, or 1 x CO{sub 2} simulation, and an enhanced greenhouse warming, or 2 x CO{sub 2} simulation, using the second generation Canadian Climate Centre general circulation model. When compared to the control climatology, the 2 x CO{sub 2} simulation exhibits a significant reduction in the total number of lows in both winter hemispheres. Although the total number of cyclones decreases, the frequency of intense cyclones increases, with this behavior being more significant in the Northern Hemisphere. Examination of the storm tracks in both simulations indicates that there is little change in their geographical positions with global warming. 10 refs., 8 figs., 4 tabs.

  6. The Trends in Excess Mortality in Winter vs. Summer in a Sub-Tropical City and Its Association with Extreme Climate Conditions.

    PubMed

    Chau, Pui Hing; Woo, Jean

    2015-01-01

    While there is literature on excess winter mortality, there are few studies examining the evolution of its trend which may be changing in parallel with global warming. This study aimed to examine the trend in the excess mortality in winter as compared to summer among the older population in a sub-tropical city and to explore its association with extreme weather. We used a retrospective study based on the registered deaths among the older population in Hong Kong during 1976-2010. An Excess Mortality for Winter versus Summer (EMWS) Index was used to quantify the excess number of deaths in winter compared to summer. Multiple linear regressions were used to analyze the trends and its association with extreme weather. Overall, the EMWS Index for ischemic heart disease, cerebrovascular diseases, chronic lower respiratory diseases, pneumonia, and other causes were 43.0%, 34.2%, 42.7%, 23.4% and 17.6%, respectively. Significant decline was observed in the EMWS Index for chronic lower respiratory diseases and other causes. The trend in the index for cerebrovascular diseases depended on the age group, with older groups showing a decline but younger groups not showing any trend. Meteorological variables, in terms of extreme weather, were associated with the trends in the EMWS Index. We concluded that shrinking excess winter mortality from cerebrovascular diseases and chronic lower respiratory diseases was found in a sub-tropical city. These trends were associated with extreme weather, which coincided with global warming.

  7. Winter cold of eastern continental boundaries induced by warm ocean waters.

    PubMed

    Kaspi, Yohai; Schneider, Tapio

    2011-03-31

    In winter, northeastern North America and northeastern Asia are both colder than other regions at similar latitudes. This has been attributed to the effects of stationary weather systems set by elevated terrain (orography), and to a lack of maritime influences from the prevailing westerly winds. However, the differences in extent and orography between the two continents suggest that further mechanisms are involved. Here we show that this anomalous winter cold can result in part from westward radiation of large-scale atmospheric waves--nearly stationary Rossby waves--generated by heating of the atmosphere over warm ocean waters. We demonstrate this mechanism using simulations with an idealized general circulation model, with which we show that the extent of the cold region is controlled by properties of Rossby waves, such as their group velocity and its dependence on the planetary rotation rate. Our results show that warm ocean waters contribute to the contrast in mid-latitude winter temperatures between eastern and western continental boundaries not only by warming western boundaries, but also by cooling eastern boundaries.

  8. Nutritional condition of Pacific Black Brant wintering at the extremes of their range

    USGS Publications Warehouse

    Mason, D.D.; Barboza, P.S.; Ward, D.H.

    2006-01-01

    Endogenous stores of energy allow birds to survive periods of severe weather and food shortage during winter. We documented changes in lipid, protein, moisture, and ash in body tissues of adult female Pacific Black Brant (Branta bernicla nigricans) and modeled the energetic costs of wintering. Birds were collected at the extremes of their winter range, in Alaska and Baja California, Mexico. Body lipids decreased over winter for birds in Alaska but increased for those in Baja California. Conversely, body protein increased over winter for Brant in Alaska and remained stable for birds in Baja California. Lipid stores likely fuel migration for Brant wintering in Baja California and ensure winter survival for those in Alaska. Increases in body protein may support earlier reproduction for Brant in Alaska. Predicted energy demands were similar between sites during late winter but avenues of expenditure were different. Birds in Baja California spent more energy on lipid synthesis while those in Alaska incurred higher thermoregulatory costs. Estimated daily intake rates of eelgrass were similar between sites in early winter; however, feeding time was more constrained in Alaska because of high tides and short photoperiods. Despite differences in energetic costs and foraging time, Brant wintering at both sites appeared to be in good condition. We suggest that wintering in Alaska may be more advantageous than long-distance migration if winter survival is similar between sites and constraints on foraging time do not impair body condition. ?? The Cooper Ornithological Society 2006.

  9. Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming

    PubMed Central

    Cronin, Timothy W.; Tziperman, Eli

    2015-01-01

    High-latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. We use an idealized single-column atmospheric model across a range of conditions to study the polar night process of air mass transformation from high-latitude maritime air, with a prescribed initial temperature profile, to much colder high-latitude continental air. We find that a low-cloud feedback—consisting of a robust increase in the duration of optically thick liquid clouds with warming of the initial state—slows radiative cooling of the surface and amplifies continental warming. This low-cloud feedback increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature, effectively suppressing Arctic air formation. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ∼10 d for initial maritime surface air temperatures of 20 °C. These results, supplemented by an analysis of Coupled Model Intercomparison Project phase 5 climate model runs that shows large increases in cloud water path and surface cloud longwave forcing in warmer climates, suggest that the “lapse rate feedback” in simulations of anthropogenic climate change may be related to the influence of low clouds on the stratification of the lower troposphere. The results also indicate that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates. PMID:26324919

  10. Low clouds suppress Arctic air formation and amplify high-latitude continental winter warming.

    PubMed

    Cronin, Timothy W; Tziperman, Eli

    2015-09-15

    High-latitude continents have warmed much more rapidly in recent decades than the rest of the globe, especially in winter, and the maintenance of warm, frost-free conditions in continental interiors in winter has been a long-standing problem of past equable climates. We use an idealized single-column atmospheric model across a range of conditions to study the polar night process of air mass transformation from high-latitude maritime air, with a prescribed initial temperature profile, to much colder high-latitude continental air. We find that a low-cloud feedback--consisting of a robust increase in the duration of optically thick liquid clouds with warming of the initial state--slows radiative cooling of the surface and amplifies continental warming. This low-cloud feedback increases the continental surface air temperature by roughly two degrees for each degree increase of the initial maritime surface air temperature, effectively suppressing Arctic air formation. The time it takes for the surface air temperature to drop below freezing increases nonlinearly to ∼ 10 d for initial maritime surface air temperatures of 20 °C. These results, supplemented by an analysis of Coupled Model Intercomparison Project phase 5 climate model runs that shows large increases in cloud water path and surface cloud longwave forcing in warmer climates, suggest that the "lapse rate feedback" in simulations of anthropogenic climate change may be related to the influence of low clouds on the stratification of the lower troposphere. The results also indicate that optically thick stratus cloud decks could help to maintain frost-free winter continental interiors in equable climates.

  11. Potentially Extreme Population Displacement and Concentration in the Tropics Under Non-Extreme Warming

    NASA Astrophysics Data System (ADS)

    Hsiang, Solomon M.; Sobel, Adam H.

    2016-06-01

    Evidence increasingly suggests that as climate warms, some plant, animal, and human populations may move to preserve their environmental temperature. The distances they must travel to do this depends on how much cooler nearby surfaces temperatures are. Because large-scale atmospheric dynamics constrain surface temperatures to be nearly uniform near the equator, these displacements can grow to extreme distances in the tropics, even under relatively mild warming scenarios. Here we show that in order to preserve their annual mean temperatures, tropical populations would have to travel distances greater than 1000 km over less than a century if global mean temperature rises by 2 °C over the same period. The disproportionately rapid evacuation of the tropics under such a scenario would cause migrants to concentrate in tropical margins and the subtropics, where population densities would increase 300% or more. These results may have critical consequences for ecosystem and human wellbeing in tropical contexts where alternatives to geographic displacement are limited.

  12. Potentially Extreme Population Displacement and Concentration in the Tropics Under Non-Extreme Warming.

    PubMed

    Hsiang, Solomon M; Sobel, Adam H

    2016-06-09

    Evidence increasingly suggests that as climate warms, some plant, animal, and human populations may move to preserve their environmental temperature. The distances they must travel to do this depends on how much cooler nearby surfaces temperatures are. Because large-scale atmospheric dynamics constrain surface temperatures to be nearly uniform near the equator, these displacements can grow to extreme distances in the tropics, even under relatively mild warming scenarios. Here we show that in order to preserve their annual mean temperatures, tropical populations would have to travel distances greater than 1000 km over less than a century if global mean temperature rises by 2 °C over the same period. The disproportionately rapid evacuation of the tropics under such a scenario would cause migrants to concentrate in tropical margins and the subtropics, where population densities would increase 300% or more. These results may have critical consequences for ecosystem and human wellbeing in tropical contexts where alternatives to geographic displacement are limited.

  13. Potentially Extreme Population Displacement and Concentration in the Tropics Under Non-Extreme Warming

    PubMed Central

    Hsiang, Solomon M.; Sobel, Adam H.

    2016-01-01

    Evidence increasingly suggests that as climate warms, some plant, animal, and human populations may move to preserve their environmental temperature. The distances they must travel to do this depends on how much cooler nearby surfaces temperatures are. Because large-scale atmospheric dynamics constrain surface temperatures to be nearly uniform near the equator, these displacements can grow to extreme distances in the tropics, even under relatively mild warming scenarios. Here we show that in order to preserve their annual mean temperatures, tropical populations would have to travel distances greater than 1000 km over less than a century if global mean temperature rises by 2 °C over the same period. The disproportionately rapid evacuation of the tropics under such a scenario would cause migrants to concentrate in tropical margins and the subtropics, where population densities would increase 300% or more. These results may have critical consequences for ecosystem and human wellbeing in tropical contexts where alternatives to geographic displacement are limited. PMID:27278823

  14. Potentially Extreme Population Displacement and Concentration in the Tropics Under Non-Extreme Warming.

    PubMed

    Hsiang, Solomon M; Sobel, Adam H

    2016-01-01

    Evidence increasingly suggests that as climate warms, some plant, animal, and human populations may move to preserve their environmental temperature. The distances they must travel to do this depends on how much cooler nearby surfaces temperatures are. Because large-scale atmospheric dynamics constrain surface temperatures to be nearly uniform near the equator, these displacements can grow to extreme distances in the tropics, even under relatively mild warming scenarios. Here we show that in order to preserve their annual mean temperatures, tropical populations would have to travel distances greater than 1000 km over less than a century if global mean temperature rises by 2 °C over the same period. The disproportionately rapid evacuation of the tropics under such a scenario would cause migrants to concentrate in tropical margins and the subtropics, where population densities would increase 300% or more. These results may have critical consequences for ecosystem and human wellbeing in tropical contexts where alternatives to geographic displacement are limited. PMID:27278823

  15. The assessment of contributions of SST anomalies to the interannual variability of winter extreme precipitation in Southeast China

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Fraedrich, K.; Zhu, X.; Sielmann, F.; Zhi, X.

    2014-12-01

    Tropical SST anomalies are among the largest drivers of circulation regime changes on interannual time scales due to its characteristic heat capacity decay time scales. The with extreme precipitation associated circulation anomalies and the corresponding atmospheric response to SST anomalies are derived from ECMWF ERA-Interim reanalysis data by employing composite analysis and lagged maximum covariance analysis (MCA). The results show that the interannual variability of extreme winter precipitation in Southeast China is in close accordance with the interannual variability of total winter precipitation. Both are associated with similar abnormal circulation regimes, but for extreme precipitation events the circulation anomalies are significantly intensified. In addition, two main moisture transport channels are captured: one extends from the North Indian Ocean through India and the Bay of Bengal to South China, and the other from the West Pacific Ocean through Maritime Continent and South China Sea towards South China, which are related to the preceding autumn SST patterns, El Niño and the Indian Ocean dipole (IOD), respectively. El Niño (La Niña) SST anomalies induce anomalous anticyclonic (cyclonic) circulation over Philippine Sea, which is favorable (unfavorable) to warm and humid air transport to South China from the tropical West Pacific by southwesterly (northeasterly) anomalies. Under these circulations, northeasterlies of East Asian Winter Monsoon are weakened (strengthened) resulting in extreme precipitation to be more (less) frequent in Southeast China. During the positive (negative) IOD phase, abundant (reduced) moisture transport to South China from tropical regions through India and Bay of Bengal is observed due to the weakened (strengthened) Walker circulations and abnormal anticyclonic (cyclonic) circulation over India, leading to a higher (lower) likelihood for extreme precipitation events in Southeast China.

  16. Short-term cropland responses to temperature extreme events during late winter

    NASA Astrophysics Data System (ADS)

    De Simon, G.; Alberti, G.; Delle Vedove, G.; Peressotti, A.; Zaldei, A.; Miglietta, F.

    2013-04-01

    In recent years, several studies have focused on terrestrial ecosystem response to extreme events. Most of this research has been conducted in natural ecosystems, but few have considered agro-ecosystems. In this study, we investigated the impact of a manipulated warmer or cooler late winter-early spring on the carbon budget and final harvest of a soybean crop (Glycine max (L.) Merr.). Soil temperature was altered by manipulating soil albedo by covering the soil surface with a layer of inert silica gravel. We tested three treatments: cooling (Co), warming (W), mix (M) and control (C). An automated system continuously measured soil heterotrophic respiration (Rh), soil temperature profiles, and soil water content across the entire year in each plot. Phenological phases were periodically assessed and final harvest was measured in each plot. Results showed that treatments had only a transient effect on daily Rh rates which did not result in a total annual carbon budget significantly different from control, even though cooling showed a significant reduction in final harvest. We also observed anticipation in seed germination in both W and M treatments and a delay in germination for Co. Moreover, plant density and growth increased in W and M and decreased in Co.

  17. Short-term cropland responses to temperature extreme events during late winter

    NASA Astrophysics Data System (ADS)

    De Simon, G.; Alberti, G.; Delle Vedove, G.; Peressotti, A.; Zaldei, A.; Miglietta, F.

    2013-08-01

    In recent years, several studies have focused on terrestrial ecosystem response to extreme events. Most of this research has been conducted in natural ecosystems, but few have considered agroecosystems. In this study, we investigated the impact of a manipulated warmer or cooler late winter/early spring on the carbon budget and final harvest of a soybean crop (Glycine max (L.) Merr.). Soil temperature was altered by manipulating soil albedo by covering the soil surface with a layer of inert silica gravel. We tested three treatments - cooling (Co), warming (W), mix (M) - and control (C). An automated system continuously measured soil heterotrophic respiration (Rh), soil temperature profiles, and soil water content across the entire year in each plot. Phenological phases were periodically assessed and final harvest was measured in each plot. Results showed that treatments had only a transient effect on daily Rh rates, which did not result in a total annual carbon budget significantly different from control, even though cooling showed a significant reduction in final harvest. We also observed anticipation in emergence in both W and M treatments and a delay in emergence for Co. Moreover, plant density and growth increased in W and M and decreased in Co. In conclusion, from the results of our experiment we can assert that an increase in the frequency of both heat and cold waves is unlikely to have large effects on the overall annual carbon balance of irrigated croplands.

  18. Influence of atmospheric energy transport on amplification of winter warming in the Arctic

    NASA Astrophysics Data System (ADS)

    Alekseev, Genrikh; Kuzmina, Svetlana; Urazgildeeva, Aleksandra; Bobylev, Leonid

    2016-04-01

    The study was performed on base reanalysis ERA/Interim to discover the link between amplified warming in the high Arctic and the atmospheric transport of heat and water vapor through the 70 ° N. The partitioning transports across the Atlantic and Pacific "gates" is established the link between variations of atmospheric flux through the "gates" and a larger part of the variability of the average surface air temperature, water vapor content and its trends in the winter 1980-2014. Influence of winter (December-February) atmospheric transport across the Atlantic "gate" at the 1000 hPa on variability of average for January-February surface air temperature to north 70° N is estimated correlation coefficient 0.75 and contribution to the temperature trend 40%. These results for the first time denote the leading role of increasing atmospheric transport on the amplification of winter warming in the high Arctic. The investigation is supported with RFBR project 15-05-03512.

  19. Observed decreases in the Canadian outdoor skating season due to recent winter warming

    NASA Astrophysics Data System (ADS)

    Damyanov, Nikolay N.; Damon Matthews, H.; Mysak, Lawrence A.

    2012-03-01

    Global warming has the potential to negatively affect one of Canada’s primary sources of winter recreation: hockey and ice skating on outdoor rinks. Observed changes in winter temperatures in Canada suggest changes in the meteorological conditions required to support the creation and maintenance of outdoor skating rinks; while there have been observed increases in the ice-free period of several natural water bodies, there has been no study of potential trends in the duration of the season supporting the construction of outdoor skating rinks. Here we show that the outdoor skating season (OSS) in Canada has significantly shortened in many regions of the country as a result of changing climate conditions. We first established a meteorological criterion for the beginning, and a proxy for the length of the OSS. We extracted this information from daily maximum temperature observations from 1951 to 2005, and tested it for significant changes over time due to global warming as well as due to changes in patterns of large-scale natural climate variability. We found that many locations have seen a statistically significant decrease in the OSS length, particularly in Southwest and Central Canada. This suggests that future global warming has the potential to significantly compromise the viability of outdoor skating in Canada.

  20. North Atlantic Surface Winds Examined as the Source of Warm Advection into Europe in Winter

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Angell, J. K.; Ardizzone, J.; Atlas, Robert; Schubert, S.; Starr, D.; Wu, M.-L.

    2002-01-01

    When from the southwest, North Atlantic ocean surface winds are known to bring warm and moist airmasses into central Europe in winter. By tracing backward trajectories from western Europe, we establish that these airmasses originate in the southwestern North Atlantic, in the very warm regions of the Gulf Stream. Over the eastern North Atlantic, Lt the gateway to Europe, the ocean-surface winds changed directions in the second half of the XXth century, those from the northwest and from the southeast becoming so infrequent, that the direction from the southwest became even more dominant. For the January-to-March period, the strength of south-westerlies in this region, as well as in the source region, shows in the years 1948-1995 a significant increase, above 0.2 m/sec/ decade. Based on the sensitivity of the surface temperature in Europe, slightly more than 1 C for a 1m/sec increase in the southwesterly wind, found in the previous studies, the trend in the warm advection accounts for a large part of the warming in Europe established for this period in several reports. However, for the most recent years, 1996-2001, the positive trend in the southwesterly advection appears to be is broken, which is consistent with unseasonally cold events reported in Europe in those winters. This study had, some bearing on evaluating the respective roles of the North Atlantic Oscillation and the Greenhouse Gas Global warming, GGG, in the strong winter warming observed for about half a century over the northern-latitude continents. Changes in the ocean-surface temperatures induced by GGG may have produced the dominant southwesterly direction of the North Atlantic winds. However, this implies a monotonically (apart from inherent interannual variability) increasing advection, and if the break in the trend which we observe after 1995 persists, this mechanism is counter-indicated. The 1948-1995 trend in the south-westerlies could then be considered to a large degree attributable to the

  1. The 2015-2016 Arctic winter: Perspectives on extremes in polar processing and meteorological variability from the 12-year record of Aura Microwave Limb Sounder measurements

    NASA Astrophysics Data System (ADS)

    Santee, Michelle; Manney, Gloria; Lambert, Alyn; Livesey, Nathaniel; Lawrence, Zachary

    2016-04-01

    In the last decade, the Arctic lower stratosphere has seen some of the most dynamically disturbed winters, with stratospheric sudden warmings that curtailed polar processing early in the season and limited chemical ozone loss, as well as several winters marked by exceptionally cold conditions and severe chemical ozone loss. The occurrence in recent winters of different combinations of extreme meteorological conditions, and their impact on polar chemical processes, has underscored the Arctic stratosphere's sensitivity to a spectrum of dynamical variability. Launched as part of NASA's Aura satellite in July 2004, the Microwave Limb Sounder (MLS) provides an extensive suite of measurements enabling quantification of polar processing and chemical ozone loss. Here we use MLS observations in conjunction with meteorological analyses in a comprehensive analysis of the Arctic winter of 2015-2016. An unusually large volume of low temperatures in the early winter led to strong depletion in gas-phase HNO3 and H2O associated with polar stratospheric cloud formation. As a consequence of this early-winter processing and an elongated vortex with significant portions exposed to sunlight, substantial chlorine activation (enhanced abundances of ClO, depressed abundances of HCl) was evident far earlier than is typical in Arctic winter. The degree of polar processing and chemical ozone loss in this winter will be placed in the context of the previous 11 Arctic winters observed by Aura MLS.

  2. Intensity of heat stress in winter wheat—phenology compensates for the adverse effect of global warming

    NASA Astrophysics Data System (ADS)

    Eyshi Rezaei, Ehsan; Siebert, Stefan; Ewert, Frank

    2015-02-01

    Higher temperatures during the growing season are likely to reduce crop yields with implications for crop production and food security. The negative impact of heat stress has also been predicted to increase even further for cereals such as wheat under climate change. Previous empirical modeling studies have focused on the magnitude and frequency of extreme events during the growth period but did not consider the effect of higher temperature on crop phenology. Based on an extensive set of climate and phenology observations for Germany and period 1951-2009, interpolated to 1 × 1 km resolution and provided as supplementary data to this article (available at stacks.iop.org/ERL/10/024012/mmedia), we demonstrate a strong relationship between the mean temperature in spring and the day of heading (DOH) of winter wheat. We show that the cooling effect due to the 14 days earlier DOH almost fully compensates for the adverse effect of global warming on frequency and magnitude of crop heat stress. Earlier heading caused by the warmer spring period can prevent exposure to extreme heat events around anthesis, which is the most sensitive growth stage to heat stress. Consequently, the intensity of heat stress around anthesis in winter crops cultivated in Germany may not increase under climate change even if the number and duration of extreme heat waves increase. However, this does not mean that global warning would not harm crop production because of other impacts, e.g. shortening of the grain filling period. Based on the trends for the last 34 years in Germany, heat stress (stress thermal time) around anthesis would be 59% higher in year 2009 if the effect of high temperatures on accelerating wheat phenology were ignored. We conclude that climate impact assessments need to consider both the effect of high temperature on grain set at anthesis but also on crop phenology.

  3. Body shrinkage due to Arctic warming reduces red knot fitness in tropical wintering range.

    PubMed

    van Gils, Jan A; Lisovski, Simeon; Lok, Tamar; Meissner, Włodzimierz; Ożarowska, Agnieszka; de Fouw, Jimmy; Rakhimberdiev, Eldar; Soloviev, Mikhail Y; Piersma, Theunis; Klaassen, Marcel

    2016-05-13

    Reductions in body size are increasingly being identified as a response to climate warming. Here we present evidence for a case of such body shrinkage, potentially due to malnutrition in early life. We show that an avian long-distance migrant (red knot, Calidris canutus canutus), which is experiencing globally unrivaled warming rates at its high-Arctic breeding grounds, produces smaller offspring with shorter bills during summers with early snowmelt. This has consequences half a world away at their tropical wintering grounds, where shorter-billed individuals have reduced survival rates. This is associated with these molluscivores eating fewer deeply buried bivalve prey and more shallowly buried seagrass rhizomes. We suggest that seasonal migrants can experience reduced fitness at one end of their range as a result of a changing climate at the other end.

  4. Body shrinkage due to Arctic warming reduces red knot fitness in tropical wintering range.

    PubMed

    van Gils, Jan A; Lisovski, Simeon; Lok, Tamar; Meissner, Włodzimierz; Ożarowska, Agnieszka; de Fouw, Jimmy; Rakhimberdiev, Eldar; Soloviev, Mikhail Y; Piersma, Theunis; Klaassen, Marcel

    2016-05-13

    Reductions in body size are increasingly being identified as a response to climate warming. Here we present evidence for a case of such body shrinkage, potentially due to malnutrition in early life. We show that an avian long-distance migrant (red knot, Calidris canutus canutus), which is experiencing globally unrivaled warming rates at its high-Arctic breeding grounds, produces smaller offspring with shorter bills during summers with early snowmelt. This has consequences half a world away at their tropical wintering grounds, where shorter-billed individuals have reduced survival rates. This is associated with these molluscivores eating fewer deeply buried bivalve prey and more shallowly buried seagrass rhizomes. We suggest that seasonal migrants can experience reduced fitness at one end of their range as a result of a changing climate at the other end. PMID:27174985

  5. Has global warming changed timing of winter-spring streamflows over North America?

    NASA Astrophysics Data System (ADS)

    Kam, J.; Knutson, T. R.; Milly, P. C. D.

    2015-12-01

    Wherever snowmelt runoff substantially contributes to winter-spring streamflows, warmer winter-spring temperature can accelerate snow melt and reduce later streamflows. These changes can adversely affect human activities and ecological communities (e.g. flood, drought, salmon survival rate, and blooming season). Here we investigate changes in timing of winter-spring streamflows over North America (NA) during 1933-2013 and 1951-2000 using observed streamflow and simulated runoff from pre-industrial (unforced) control and historical (realistically forced) runs from the Geophysical Fluid Dynamics Laboratory Climate Model version 3. The study regions are north of 41˚N in NA. We analyze winter-spring center of volume date (WSCV), the date by which half of the accumulated January through June daily streamflow volume occurs. We first performed a sliding trend analysis of WSCV for time periods starting in various years (1951 through 1984) and ending in 2000. We found that the observed decreasing trends (Theil-Sen slopes) of WSCV over the northeast and northwest U.S. regions are at the edge of detectability (i.e., lie near the edge of the 5th-95th percentile envelope of control runs) for trends beginning any time between 1950 and 1970, but are consistent with the envelope of historical runs for all beginning trend years. Interestingly, for the 1933-2013 analysis, results for the northwest U.S. show that the observed trends of WSCV are positive for periods beginning as early as the mid-1960s, and inconsistent with historical runs for periods beginning in the mid-1950s and later. Aside from this inconsistency, observed trends to 2013 are consistent with both control and historical runs. This study suggests that internal variability has played a major role in timing of winter-spring streamflows to date, despite global warming, and thus that clear detection and attribution of WSCV trends in the study regions may require longer streamflow records than those now available.

  6. Cropland responses to extreme winter temperature events: results from a manipulation experiment in north-eastern Italy

    NASA Astrophysics Data System (ADS)

    De Simon, G.; Alberti, G.; Delle Vedove, G.; Peressotti, A.; Zaldei, A.; Miglietta, F.

    2011-12-01

    In the last years, several studies has focused on terrestrial ecosystem response to climate warming. Most of them have been conducted on natural ecosystems (forests or grasslands), but few have considered intensively managed ecosystems such as croplands despite of their global extension. In particular, extreme events, such as temperature changes outside the growing season (winter) when soil is not covered by plants, can have a strong impact on soil respiration, residues decomposition, yield and overall net biome production (NBP). In this study, we investigated the response of soil respiration (total and heterotrophic), aboveground NPP, yield and NBP on a soybean crop (Glycine max (L.) Merr.) due to a manipulated warmer or cooler winter. The experiment was carried out in Beano (46°00' N 13°01'E, Italy). Soil albedo and soil temperature were manipulated by covering soil surface during late winter with a layer of inert ceramized silica gravel. We tested three treatments with three replicates each: cooling (Co; white gravel), warming (W; black gravel), mix (M; black and white 4:1 gravel) and control (C; bare soil). An automated soil respiration system measured continuously total soil CO2 efflux across all the year and heterotrophic respiration after sowing in root exclusion subplots. Additionally, soil temperature profiles (0, 2.5, 5 and 10 cm depth), soil water content (between 5 and 10 cm depth) were monitored in each plot. After sowing, soybean phenological phases were periodically assessed and final yield was measured in each plot. Preliminary results showed a significant change in upper soil temperature between gravel application and canopy closure (maximum of + 5.8 °C and - 6.8 °C in the warming and cooling treatments, respectively). However, warming had only a transient effect on soil respiration (increase) before sowing. Thereafter, as soon as fresh organic matter availability decreased, soil respiration rate decreased and annual budget was not

  7. Cropland responses to extreme winter temperature events: results from a manipulation experiment in north-eastern Italy

    NASA Astrophysics Data System (ADS)

    De Simon, G.; Alberti, G.; Delle Vedove, G.; Peressotti, A.; Zaldei, A.; Miglietta, F.

    2012-04-01

    In the last years, several studies has focused on terrestrial ecosystem response to climate warming. Most of them have been conducted on natural ecosystems (forests or grasslands), but few have considered intensively managed ecosystems such as croplands despite of their global extension. In particular, extreme events, such as temperature changes outside the growing season (winter) when soil is not covered by plants, can have a strong impact on soil respiration, residues decomposition, yield and overall net biome production (NBP). In this study, we investigated the response of soil respiration (total and heterotrophic), aboveground NPP, yield and NBP on a soybean crop (Glycine max (L.) Merr.) due to a manipulated warmer or cooler winter. The experiment was carried out in Beano (46°00' N 13°01'E, Italy). Soil albedo and soil temperature were manipulated by covering soil surface during late winter with a layer of inert ceramized silica gravel. We tested three treatments with three replicates each: cooling (Co; white gravel), warming (W; black gravel), mix (M; black and white 4:1 gravel) and control (C; bare soil). An automated soil respiration system measured continuously total soil CO2 efflux across all the year and heterotrophic respiration after sowing in root exclusion subplots. Additionally, soil temperature profiles (0, 2.5, 5 and 10 cm depth), soil water content (between 5 and 10 cm depth) were monitored in each plot. After sowing, soybean phenological phases were periodically assessed and final yield was measured in each plot. Results showed a significant change in upper soil temperature between gravel application and canopy closure (maximum of + 5.8 °C and - 6.8 °C in the warming and cooling treatments, respectively). However, warming had only a transient effect on soil respiration (increase) before sowing. Thereafter, as soon as fresh organic matter availability decreased, soil respiration rate decreased and annual budget was not significantly different

  8. Energy consumption and the unexplained winter warming over northern Asia and North America

    NASA Astrophysics Data System (ADS)

    Zhang, Guang J.; Cai, Ming; Hu, Aixue

    2013-05-01

    The worldwide energy consumption in 2006 was close to 498 exajoules. This is equivalent to an energy convergence of 15.8TW into the populated regions, where energy is consumed and dissipated into the atmosphere as heat. Although energy consumption is sparsely distributed over the vast Earth surface and is only about 0.3% of the total energy transport to the extratropics by atmospheric and oceanic circulations, this anthropogenic heating could disrupt the normal atmospheric circulation pattern and produce a far-reaching effect on surface air temperature. We identify the plausible climate impacts of energy consumption using a global climate model. The results show that the inclusion of energy use at 86 model grid points where it exceeds 0.4Wm-2 can lead to remote surface temperature changes by as much as 1K in mid- and high latitudes in winter and autumn over North America and Eurasia. These regions correspond well to areas with large differences in surface temperature trends between observations and global warming simulations forced by all natural and anthropogenic forcings. We conclude that energy consumption is probably a missing forcing for the additional winter warming trends in observations.

  9. Winter survival and deacclimation of perennials under warming climate: physiological perspectives.

    PubMed

    Pagter, Majken; Arora, Rajeev

    2013-01-01

    Appropriate timing and rate of cold deacclimation and the ability to reacclimate are important components of winter survival of perennials in temperate and boreal zones. In association with the progressive increase in atmospheric CO₂, temperate and boreal winters are becoming progressively milder, and temperature patterns are becoming irregular with increasing risk of unseasonable warm spells during the colder periods of plants' annual cycle. Because deacclimation is mainly driven by temperature, these changes pose a risk for untimely/premature deacclimation, thereby rendering plant tissue vulnerable to freeze-injury by a subsequent frost. Research also indicates that elevated CO₂ may directly impact deacclimation. Hence, understanding the underlying cellular mechanisms of how deacclimation and reacclimation capacity are affected by changes in environmental conditions is important to ensure winter survival and the sustainability of plant sources under changing climate. Relative to cold acclimation, deacclimation is a little studied process, but the limited evidence points to specific changes occurring in the transcriptome and proteome during deacclimation. Loss of freezing tolerance is additionally associated with substantial changes in cell/tissue-water relations and carbohydrate metabolism; the latter also impacted by temperature-driven, altered respiratory metabolism. This review summarizes recent progress in understanding the physiological mechanisms of deacclimation and how they may be impacted by climate change. PMID:22583023

  10. Winter survival and deacclimation of perennials under warming climate: physiological perspectives.

    PubMed

    Pagter, Majken; Arora, Rajeev

    2013-01-01

    Appropriate timing and rate of cold deacclimation and the ability to reacclimate are important components of winter survival of perennials in temperate and boreal zones. In association with the progressive increase in atmospheric CO₂, temperate and boreal winters are becoming progressively milder, and temperature patterns are becoming irregular with increasing risk of unseasonable warm spells during the colder periods of plants' annual cycle. Because deacclimation is mainly driven by temperature, these changes pose a risk for untimely/premature deacclimation, thereby rendering plant tissue vulnerable to freeze-injury by a subsequent frost. Research also indicates that elevated CO₂ may directly impact deacclimation. Hence, understanding the underlying cellular mechanisms of how deacclimation and reacclimation capacity are affected by changes in environmental conditions is important to ensure winter survival and the sustainability of plant sources under changing climate. Relative to cold acclimation, deacclimation is a little studied process, but the limited evidence points to specific changes occurring in the transcriptome and proteome during deacclimation. Loss of freezing tolerance is additionally associated with substantial changes in cell/tissue-water relations and carbohydrate metabolism; the latter also impacted by temperature-driven, altered respiratory metabolism. This review summarizes recent progress in understanding the physiological mechanisms of deacclimation and how they may be impacted by climate change.

  11. Winter warming as an important co-driver for Betula nana growth in western Greenland during the past century

    PubMed Central

    Hollesen, Jørgen; Buchwal, Agata; Rachlewicz, Grzegorz; Hansen, Birger U; Hansen, Marc O; Stecher, Ole; Elberling, Bo

    2015-01-01

    Growing season conditions are widely recognized as the main driver for tundra shrub radial growth, but the effects of winter warming and snow remain an open question. Here, we present a more than 100 years long Betula nana ring-width chronology from Disko Island in western Greenland that demonstrates a highly significant and positive growth response to both summer and winter air temperatures during the past century. The importance of winter temperatures for Betula nana growth is especially pronounced during the periods from 1910–1930 to 1990–2011 that were dominated by significant winter warming. To explain the strong winter importance on growth, we assessed the importance of different environmental factors using site-specific measurements from 1991 to 2011 of soil temperatures, sea ice coverage, precipitation and snow depths. The results show a strong positive growth response to the amount of thawing and growing degree-days as well as to winter and spring soil temperatures. In addition to these direct effects, a strong negative growth response to sea ice extent was identified, indicating a possible link between local sea ice conditions, local climate variations and Betula nana growth rates. Data also reveal a clear shift within the last 20 years from a period with thick snow depths (1991–1996) and a positive effect on Betula nana radial growth, to a period (1997–2011) with generally very shallow snow depths and no significant growth response towards snow. During this period, winter and spring soil temperatures have increased significantly suggesting that the most recent increase in Betula nana radial growth is primarily triggered by warmer winter and spring air temperatures causing earlier snowmelt that allows the soils to drain and warm quicker. The presented results may help to explain the recently observed ‘greening of the Arctic’ which may further accelerate in future years due to both direct and indirect effects of winter warming. PMID:25788025

  12. Extreme temperature events over the South America during winter and summer: A comparison between coupled global models and reanalysis data

    NASA Astrophysics Data System (ADS)

    Custodio, M. D.; Da Rocha, R.

    2012-12-01

    The variations of extreme climatic events had been described and analyzed in the scientific literature. Both extremes of precipitation and temperature until now are not well represented by regional or global climate models. Additionally, it is important to characterize possible changes in extreme events. The only certainty is that the extreme events such as heat waves, floods, droughts, or storms may imply in severe societal and economical impacts, since they cause significant damage to agriculture, ecology and infrastructure, injury, and loss of life. Therefore, in a scenario of global warming it is necessary understanding and explaining extreme events and to know if global models may represent these events. The South America (SA) climate is characterized by different precipitation regimes and its variability has great influences of the large scale phenomena in the interanual (El Niño South Oscilation - ENSO) and intraseasonal (Maden Julian Oscilation - MJO) timescales. Normally, the Coupled Global Climate Models (CGCM) use low horizontal resolution and present difficult to simulate these low frequency variability phenomena. The goal of this work is to evaluate the performance of two versions of the High-Resolution Global Environmental Models in capturing the signal of interannual and intraseasonal variability of temperature over South America (SA) during austral summer and winter. The coupled models have 135 (HadGEM) and 90 km (HiGEM) of horizontal resolution. The simulated climatologies were compared with temperature data from ERA-Interim (ERAIN) for the period 1989 to 2008 while for the models the period was 1979-2008. The temperature monthly time-series were filtered on the interanual (period > 365 days) and daily time-series on the intraseasonal (30-90 days) timescales using the Fast Fourier Transform (FFT). Extremes temperature (warm and cold periods) are defined according to the 75th and 25th quartiles of the temperature anomaly distributions on interanual

  13. A Global Analysis of the Link between Soil Moisture Dynamics and Warm Extremes.

    NASA Astrophysics Data System (ADS)

    Casagrande, E.; Kondapalli, N. K.; Mueller, B.; Miralles, D. G.; Molini, A.

    2014-12-01

    Under future climatic scenarios long-lasting warm extremes, such as heat waves, are expected to become more intense, persistent and frequent for both temperate and arid regions, resulting in diverse but nonetheless significant impacts for the human health, sustainable development and economy of these regions. As the underlying processes responsible for triggering and sustaining warm extremes are extremely variegate and yet not well understood, the occurrence of extreme events such heat waves and prolonged droughts results exceedingly difficult to predict and model. Major uncertainties arise from the fact that warm extremes mainly derive from the interplay of large-scale atmospheric processes and local feedbacks operating across very different spatial and temporal scales, and are characterized by several thresholds, limiting factors and non-linearities determining their deviation from the "classical" extreme-value theory.In this study we explore - from a global point of view - the role of local and synoptic dynamical components in initiating warm extremes and in determining their spatial and temporal clustering. Previous studies have already highlighted the role of large negative soil moisture anomalies in causing and sustaining long periods of dry and hot weather. For this reason we propose here a novel approach to the characterization of warm extremes, based on the conditioning of traditional air temperature quintile statistics to antecedent soil moisture conditions. Case studies from different climatic regimes are shown in order to prove the major and varied role of antecedent soil moisture conditions across the different regions of the world. In addition, we also investigate the connection between regional climate features and large-scale dynamics during warm extremes by the joint usage of classical diagnostic analysis and novel statistics for the detection of cross-scale interactions.

  14. Are Stronger North-Atlantic Southwesterlies Forcing to the Late Winter Warming in Europe?

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Atlas, Robert; Chou, S.-H.; Jusem, J. C.; Pielke, R. A., Sr.; Chase, T. N.; Rogers, J.; Russell, G. L.; Schubert, S. D.; Sud, Y. C.

    2001-01-01

    We examine a possible mechanism leading to late-winter warming and thus to an early spring in Europe. From the NCEP Reanalysis, we extract for the years 1948-1999 ocean-surface winds over the eastern North Atlantic, and air temperatures at the surface, T(sub s), and at the 500 mb level, T(sub 500), in late-winter and spring. T(sub s) is extracted at six European locations, all at 50.5 N, ranging in longitude from 1.9 E (northeastern France) to 26.2 E (Ukraine). To quantify the advection of maritime air into Europe, we evaluate for 3-pentad groups the Index I(sub na) of the southwesterlies at 45 N; 20 W: I(sub na) is the average wind speed at this point if the direction is from the quadrant 180-270 deg (when the direction is different, the contribution counts as zero). In late winter correlations C(sub it) between the Index I(sub na) and the temperature T(sub s) are substantial, up to the 0.6 level, in western Europe (but weaker correlations for Poland and Ukraine). C(sub it) drops sharply by mid-March, taking occasionally negative values subsequently. This drop in C(sub it) indicates that maritime air advection is no longer associated closely with the surface-air warming, the role of immolation becomes important, and thus the drop in C(sub it) marks the arrival of spring. Correlations C(sub i delta) between I(sub na) and our lapse-rate parameter delta, the difference between T(sub s) and T(sub 500), indicate that the flow of warm maritime-air from the North Atlantic into this 'corridor' at 50.5 N is predominantly at low tropospheric level. By computing the best linear fit to I(sub na) and T(sub s), the trends for the period 1948-1999 are evaluated. The trends are appreciable in the second half of February and the first half of March. Our 3-pentad analysis points to the interval from mid-February to mid-March as the end-of-winter period in which the southwesterlies over the eastern North Atlantic become stronger and the surface-air temperatures in Europe rise

  15. Atmospheric response to Indian Ocean Dipole forcing: changes of Southeast China winter precipitation under global warming

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Sielmann, Frank; Fraedrich, Klaus; Zhi, Xiefei

    2016-05-01

    To investigate the relationship between autumn Indian Ocean Dipole (IOD) events and the subsequent winter precipitation in Southeast China (SEC), observed fields of monthly precipitation, sea surface temperature (SST) and atmospheric circulation are subjected to a running and a maximum correlation analysis. The results show a significant change of the relevance of IOD for the early modulation of SEC winter precipitation in the 1980s. After 1980, positive correlations suggest prolonged atmospheric responses to IOD forcing, which are linked to an abnormal moisture supply initiated in autumn and extended into the subsequent winter. Under global warming two modulating factors are relevant: (1) an increase of the static stability has been observed suppressing vertical heat and momentum transports; (2) a positive (mid-level) cloud-radiation feedback jointly with the associated latent heating (apparent moisture sink Q2) explains the prolongation of positive as well as negative SST anomalies by conserving the heating (apparent heat source Q1) in the coupled atmosphere-ocean system. During the positive IOD events in fall (after 1980) the dipole heating anomalies in the middle and lower troposphere over the tropical Indian Ocean are prolonged to winter by a positive mid-level cloud-radiative feedback with latent heat release. Subsequently, thermal adaptation leads to an anticyclonic anomaly over Eastern India overlying the anomalous cooling SST of the tropical Eastern Indian Ocean enhancing the moisture flow from the tropical Indian Ocean through the Bay of Bengal into South China, following the northwestern boundary of the anticyclonic circulation anomaly over east India, thereby favoring abundant precipitation in SEC.

  16. Global warming and changes in risk of concurrent climate extremes: Insights from the 2014 California drought

    NASA Astrophysics Data System (ADS)

    AghaKouchak, Amir; Cheng, Linyin; Mazdiyasni, Omid; Farahmand, Alireza

    2014-12-01

    Global warming and the associated rise in extreme temperatures substantially increase the chance of concurrent droughts and heat waves. The 2014 California drought is an archetype of an event characterized by not only low precipitation but also extreme high temperatures. From the raging wildfires, to record low storage levels and snowpack conditions, the impacts of this event can be felt throughout California. Wintertime water shortages worry decision-makers the most because it is the season to build up water supplies for the rest of the year. Here we show that the traditional univariate risk assessment methods based on precipitation condition may substantially underestimate the risk of extreme events such as the 2014 California drought because of ignoring the effects of temperature. We argue that a multivariate viewpoint is necessary for assessing risk of extreme events, especially in a warming climate. This study discusses a methodology for assessing the risk of concurrent extremes such as droughts and extreme temperatures.

  17. The Robust Dynamical Contribution to Precipitation Extremes in Idealized Warming Simulations across Model Resolutions

    SciTech Connect

    Lu, Jian; Leung, Lai-Yung R.; Yang, Qing; Chen, Gang; Collins, William D.; Li, Fuyu; Hou, Zhangshuan; Feng, Xuelei

    2014-04-28

    The impact of the circulation shift under climate warming on the distribution of precipitation extremes and the associated sensitivity to model resolution are investigated using the aquaplanet Community Atmosphere Model CAM3. The response of the probability density function of the precipitation to a uniform SST warming can be interpreted as superimposition of a dynamically induced poleward shift and a thermodynamically induced upward shift toward higher intensities, which give rise to manyfold increase in the frequency of the most extreme categories of the precipitation events at the poleward side of the midlatitude storm track. Meanwhile, the thermodynamic contribution to the intensification of the precipitation extremes is substantially less than expected from the Clausius-Clapeyron relation, implicative of significant change in the vertical structure of the precipitation processes. While coarser resolutions underestimate the dynamical contribution to the increase of precipitation extremes, a modest increase of the equator-to-pole SST warming gradient can have a significant opposite effect.

  18. Warm pool/cold tongue El Niño and Indian winter Monsoon

    NASA Astrophysics Data System (ADS)

    Dimri, A. P.

    2016-08-01

    In view of the recent global changes in the hydrological, glaciological, agricultural, socio-economic studies, etc., particularly, over the northern Indian region, Indian winter (December, January, February—DJF) monsoon (IWM) has important role. Geographical positioning of the Indian subcontinent having mighty Himalayas in the north and surrounding ocean in the south makes assessment of IWM important and interesting to study. During IWM, the western Himalayas (WH) receives almost one-third of annual precipitation due to eastward moving extratropical cyclonic storms, western disturbances (WDs), embedded within the large scale subtropical westerly jet (SWJ). In addition, IWM is found to be in phase with the El Niño—Southern Oscillation (ENSO). With reference to the recent decade's finding of having different phases of El Niño- warm pool (WP) and cold tongue (CT)—it is imperative to see how these phases affect IWM. In the present study a simple mechanism between IWM with different phases of these El Niño and their relationship is studied and deliberated upon. WP and CT El Niño phase composites are prepared and their corresponding role in tandem with IWM is provided. It is found that during WP (CP) El Niño phase WH (foothill of the Indian Himalayan) region receives higher amount of winter precipitation. It is attributed to the fact that equatorial central Pacific warming makes more conducive proposition for intensification of the WDs and thus associated higher precipitation over western part of the Indian Himalayas. Northward shift of confluence over northern Atlantic region during WP El Niño phase dampens the SWJ leading to longer residence time for weather events—WDs—over the WH region. In addition, strengthening of Hadley cell leads to higher northward transport of moisture from the Indian Ocean region.

  19. Extreme warm season thunderstorm systems and the urban environment

    NASA Astrophysics Data System (ADS)

    Ntelekos, Alexandros Anastasios

    The consequences of a flood are amplified when it occurs in urban environments by virtue of the large concentration of people and wealth affected. This dissertation is devoted to advancing the understanding of the ways that warm season thunderstorm systems interact with the urban environment to produce flooding. The area of study is the northeastern United States with particular focus over the urban environments of Baltimore, Washington, DC, and New York City. The complex topography of the northeastern United States, with the Appalachian Mountains to the west, and the land-ocean boundary to the east of the heavily urbanized northeastern corridor, presents the analyses with great challenges. At the same time, it increases their relevance since most of the world's urban cores are built close to complex terrain. Warm season thunderstorm systems that produce short-duration, high-intensity rain-fall events are shown to be the major flash flooding agents over the urban corridor of the northeastern US. Established theories of inadvertent weather modification by urban environments are put to the test with the use of advanced models and multiple observational techniques. The results reveal unexplored links of inadvertent weather modification arising from synergies between the urban canopy layer and the land-ocean boundary. Aerosols are also shown to play an important role in rain-fall enhancement, under certain environmental conditions that are examined through combined observational analyses and numerical model experiments. The last part of this dissertation is devoted to synthesizing the links between flooding and the urban environment to perform a critical review of the US flood policy framework. Projections of end-of-the 21st Century annual flood costs are made, and recommendations are provided for a modernization of the policy framework to more efficiently mitigate the effects of floods in the future.

  20. Life stage influences the resistance and resilience of black mangrove forests to winter climate extremes

    USGS Publications Warehouse

    Osland, Michael J.; Day, Richard H.; From, Andrew S.; McCoy, Megan L.; McLeod, Jennie L.; Kelleway, Jeffrey

    2015-01-01

    In subtropical coastal wetlands on multiple continents, climate change-induced reductions in the frequency and intensity of freezing temperatures are expected to lead to the expansion of woody plants (i.e., mangrove forests) at the expense of tidal grasslands (i.e., salt marshes). Since some ecosystem goods and services would be affected by mangrove range expansion, there is a need to better understand mangrove sensitivity to freezing temperatures as well as the implications of changing winter climate extremes for mangrove-salt marsh interactions. In this study, we investigated the following questions: (1) how does plant life stage (i.e., ontogeny) influence the resistance and resilience of black mangrove (Avicennia germinans) forests to freezing temperatures; and (2) how might differential life stage responses to freeze events affect the rate of mangrove expansion and salt marsh displacement due to climate change? To address these questions, we quantified freeze damage and recovery for different life stages (seedling, short tree, and tall tree) following extreme winter air temperature events that occurred near the northern range limit of A. germinans in North America. We found that life stage affects black mangrove forest resistance and resilience to winter climate extremes in a nonlinear fashion. Resistance to winter climate extremes was high for tall A. germinans trees and seedlings, but lowest for short trees. Resilience was highest for tall A. germinans trees. These results suggest the presence of positive feedbacks and indicate that climate-change induced decreases in the frequency and intensity of extreme minimum air temperatures could lead to a nonlinear increase in mangrove forest resistance and resilience. This feedback could accelerate future mangrove expansion and salt marsh loss at rates beyond what would be predicted from climate change alone. In general terms, our study highlights the importance of accounting for differential life stage responses and

  1. Nectar yeasts warm the flowers of a winter-blooming plant.

    PubMed

    Herrera, Carlos M; Pozo, María I

    2010-06-22

    Yeasts are ubiquitous in terrestrial and aquatic microbiota, yet their ecological functionality remains relatively unexplored in comparison with other micro-organisms. This paper formulates and tests the novel hypothesis that heat produced by the sugar catabolism of yeast populations inhabiting floral nectar can increase the temperature of floral nectar and, more generally, modify the within-flower thermal microenvironment. Two field experiments were designed to test this hypothesis for the winter-blooming herb Helleborus foetidus (Ranunculaceae). In experiment 1, the effect of yeasts on the within-flower thermal environment was tested by excluding them from flowers, while in experiment 2 the test involved artificial inoculation of virgin flowers with yeasts. Nectary temperature (T(nect)), within-flower air temperature (T(flow)) and external air temperature (T(air)) were measured on experimental and control flowers in both experiments. Experimental exclusion of yeasts from the nectaries significantly reduced, and experimental addition of yeasts significantly increased, the temperature excess of nectaries (DeltaT(nect) = T(nect) - T(air)) and the air space inside flowers in relation to the air just outside the flowers. In non-experimental flowers exposed to natural pollinator visitation, DeltaT(nect) was linearly related to log yeast cell density in nectar, and reached +6 degrees C in nectaries with the densest yeast populations. The warming effect of nectar-dwelling yeasts documented in this study suggests novel ecological mechanisms potentially linking nectarivorous microbes with winter-blooming plants and their insect pollinators.

  2. Nectar yeasts warm the flowers of a winter-blooming plant

    PubMed Central

    Herrera, Carlos M.; Pozo, María I.

    2010-01-01

    Yeasts are ubiquitous in terrestrial and aquatic microbiota, yet their ecological functionality remains relatively unexplored in comparison with other micro-organisms. This paper formulates and tests the novel hypothesis that heat produced by the sugar catabolism of yeast populations inhabiting floral nectar can increase the temperature of floral nectar and, more generally, modify the within-flower thermal microenvironment. Two field experiments were designed to test this hypothesis for the winter-blooming herb Helleborus foetidus (Ranunculaceae). In experiment 1, the effect of yeasts on the within-flower thermal environment was tested by excluding them from flowers, while in experiment 2 the test involved artificial inoculation of virgin flowers with yeasts. Nectary temperature (Tnect), within-flower air temperature (Tflow) and external air temperature (Tair) were measured on experimental and control flowers in both experiments. Experimental exclusion of yeasts from the nectaries significantly reduced, and experimental addition of yeasts significantly increased, the temperature excess of nectaries (ΔTnect = Tnect − Tair) and the air space inside flowers in relation to the air just outside the flowers. In non-experimental flowers exposed to natural pollinator visitation, ΔTnect was linearly related to log yeast cell density in nectar, and reached +6°C in nectaries with the densest yeast populations. The warming effect of nectar-dwelling yeasts documented in this study suggests novel ecological mechanisms potentially linking nectarivorous microbes with winter-blooming plants and their insect pollinators. PMID:20147331

  3. Infrared warming reduced winter wheat yields and some physiological parameters, which were mitigated by irrigation and worsened by delayed sowing.

    PubMed

    Fang, Shibo; Su, Hua; Liu, Wei; Tan, Kaiyan; Ren, Sanxue

    2013-01-01

    Winter wheat has a central role in ensuring the food security and welfare of 1.3 billion people in China. Extensive previous studies have concluded that winter wheat yields would decrease with higher temperatures, owing to warming-induced soil drying or shortening of phenophase. Temperature in China is predicted to increase by 1-5°C by 2100, which may greatly impact plant production and cause other negative effects. We performed a manipulative field experiment, creating diverse growth regimes for wheat by infrared radiation (IR) warming day and night, including IR warming only (DW), IR warming + delayed sowing dates (DS), IR warming + increased irrigation (IW), and a control (CK). The results show that IR warming increased daily average wheat canopy and soil temperatures by 2.0°C and 2.3°C, respectively. DW was associated with an advanced maturity of 10 days and yield reduction of 8.2%. IR-warming effects on the photosynthetic apparatus of wheat varied with season as well as significant differences were found in the booting stage. DS represented a worsened situation, lowering yield per plant by 16.4%, with a significant decline in aboveground biomass and functional leaf area. Wheat under DS showed double-peak patterns of diurnal gas exchange during booting stages and, consequently, lower photosynthetic capacity with high transpiration for cooling. Significantly lower actual water use efficiency and intrinsic water use efficiency from jointing to anthesis stages were also found under DS. However, IW had no significant difference from CK, irrespective of yield and photosynthesis. Therefore, we concluded that delayed sowing date may not be a good choice for winter wheat, whereas a thoroughly-watered wheat agroecosystem should be promoted in the context of global warming.

  4. Indirect Radiative Warming Effect in the Winter and Spring Arctic Associated with Aerosol Pollution from Mid-latitude Regions

    NASA Astrophysics Data System (ADS)

    Zhao, Chuanfeng; Garrett, Timothy

    2016-04-01

    Different from global cooling effects of aerosols and aerosol-cloud interactions, anthropogenic aerosols from mid-latitude are found to play an increased warming effect in the Arctic in later winter and early spring. Using four-year (2000-2003) observation of aerosol, cloud and radiation at North Slope of Alaska, it is found that the aerosols can increase cloud droplet effective radius 3 um for fixed liquid water path, and increase cloud thermal emissivity about 0.05-0.08. In other words, aerosols are associated with a warming of 1-1.6 degrees (3-5 W/m2) in the Arctic during late winter and early spring solely due to their first indirect effect. Further analysis indicates that total aerosol climate effects are even more significant (8-10 W/m2), with about 50% contribution from aerosol first indirect effect and another 50% contribution from complicated feedbacks. It also shows strong seasonal distribution of the aerosol indirect radiative effects, with warming effects in seasons other than in summer. However, only the significant warming effect in winter and spring passes through the significance test. The strong warming effect due to aerosol indirect effect could be further strengthened through following feedbacks involving the surface albedo (early ice melting).

  5. Ecosystem Carbon Dynamics in Response to Five Winters of Experimental Soil Warming and Permafrost Degradation

    NASA Astrophysics Data System (ADS)

    Mauritz, M.; Schuur, E. A. G.; Bracho, R. G.; Celis, G.; Natali, S.; Hutchings, J. A.; Salmon, V. G.; Webb, E.

    2014-12-01

    Arctic permafrost soils store 1700 Pg carbon (C), almost half the global soil C. For millennia permafrost soil C has been protected from decomposition by cold, waterlogged conditions. Warming temperatures will likely thaw permafrost, however the impact on arctic C balance is uncertain. Nutrient availability is predicted to increase with thaw depth and promote plant growth, potentially creating an ecosystem C sink. However, deeper thaw could also increase microbial respiration and eventually exceed C gains. Using data from a warming experiment in sub-arctic moist acidic tundra, designed to insulate soils in winter and stimulate permafrost degradation, we investigated spatial and temporal drivers of ecosystem C balance. Net ecosystem exchange (NEE) was measured continuously from May-September 2009-2013 using clear automated chambers; ecosystem respiration (Reco) was extrapolated from low light NEE and gross primary productivity (GPP) was derived (GPP = NEE-Reco). Five years of warming led to progressive increases in active layer depth. Active layer depth was positively correlated with cumulative growing season NEE, GPP and Reco. Although warming increased Reco the ecosystem remained a C sink during the growing season because high Reco was offset by increased plant growth and GPP. Eriophorum vaginatum growth accounted for most of the increased plant biomass, and was correlated with cumulative growing season GPP and Reco. NEE, GPP and Reco all peaked mid-season, and the mid-season amplitudes increased annually leading to higher cumulative NEE, GPP and Reco. In the shoulder seasons NEE and GPP were similar among years. In contrast, Reco increased at the end of the growing season each year, and high mid-season GPP was positively correlated with end season Reco. Thus, conditions that promoted plant growth also promoted C loss. These results suggest plant responses to permafrost thaw are an important driver of C dynamics. Reco associated with high biomass may result from

  6. How predictable is the winter extremely cold days over temperate East Asia?

    NASA Astrophysics Data System (ADS)

    Luo, Xiao; Wang, Bin

    2016-07-01

    Skillful seasonal prediction of the number of extremely cold day (NECD) has considerable benefits for climate risk management and economic planning. Yet, predictability of NECD associated with East Asia winter monsoon remains largely unexplored. The present work estimates the NECD predictability in temperate East Asia (TEA, 30°-50°N, 110°-140°E) where the current dynamical models exhibit limited prediction skill. We show that about 50 % of the total variance of the NECD in TEA region is likely predictable, which is estimated by using a physics-based empirical (P-E) model with three consequential autumn predictors, i.e., developing El Niño/La Niña, Eurasian Arctic Ocean temperature anomalies, and geopotential height anomalies over northern and eastern Asia. We find that the barotropic geopotential height anomaly over Asia can persist from autumn to winter, thereby serving as a predictor for winter NECD. Further analysis reveals that the sources of the NECD predictability and the physical basis for prediction of NECD are essentially the same as those for prediction of winter mean temperature over the same region. This finding implies that forecasting seasonal mean temperature can provide useful information for prediction of extreme cold events. Interpretation of the lead-lag linkages between the three predictors and the predictand is provided for stimulating further studies.

  7. Responses of the photosynthetic apparatus to winter conditions in broadleaved evergreen trees growing in warm temperate regions of Japan.

    PubMed

    Tanaka, Chizuru; Nakano, Takashi; Yamazaki, Jun-Ya; Maruta, Emiko

    2015-01-01

    Photosynthetic characteristics of two broadleaved evergreen trees, Quercus myrsinaefolia and Machilus thunbergii, were compared in autumn and winter. The irradiance was similar in both seasons, but the air temperature was lower in winter. Under the winter conditions, net photosynthesis under natural sunlight (Anet) in both species dropped to 4 μmol CO2 m(-2) s(-1), and the quantum yield of photosystem II (PSII) photochemistry in dark-adapted leaves (Fv/Fm) also dropped to 0.60. In both species the maximum carboxylation rates of Rubisco (V(cmax)) decreased, and the amount of Rubisco increased in winter. A decline in chlorophyll (Chl) concentration and an increase in the Chl a/b ratio in winter resulted in a reduction in the size of the light-harvesting antennae. From measurements of Chl a fluorescence parameters, both the relative fraction and the energy flux rates of thermal dissipation through other non-photochemical processes were markedly elevated in winter. The results indicate that the photosynthetic apparatus in broadleaved evergreen species in warm temperate regions responds to winter through regulatory mechanisms involving the downregulation of light-harvesting and photosynthesis coupled with increased photoprotective thermal energy dissipation to minimize photodamage in winter. These mechanisms aid a quick restart of photosynthesis without the development of new leaves in the following spring. PMID:25500451

  8. Responses of the photosynthetic apparatus to winter conditions in broadleaved evergreen trees growing in warm temperate regions of Japan.

    PubMed

    Tanaka, Chizuru; Nakano, Takashi; Yamazaki, Jun-Ya; Maruta, Emiko

    2015-01-01

    Photosynthetic characteristics of two broadleaved evergreen trees, Quercus myrsinaefolia and Machilus thunbergii, were compared in autumn and winter. The irradiance was similar in both seasons, but the air temperature was lower in winter. Under the winter conditions, net photosynthesis under natural sunlight (Anet) in both species dropped to 4 μmol CO2 m(-2) s(-1), and the quantum yield of photosystem II (PSII) photochemistry in dark-adapted leaves (Fv/Fm) also dropped to 0.60. In both species the maximum carboxylation rates of Rubisco (V(cmax)) decreased, and the amount of Rubisco increased in winter. A decline in chlorophyll (Chl) concentration and an increase in the Chl a/b ratio in winter resulted in a reduction in the size of the light-harvesting antennae. From measurements of Chl a fluorescence parameters, both the relative fraction and the energy flux rates of thermal dissipation through other non-photochemical processes were markedly elevated in winter. The results indicate that the photosynthetic apparatus in broadleaved evergreen species in warm temperate regions responds to winter through regulatory mechanisms involving the downregulation of light-harvesting and photosynthesis coupled with increased photoprotective thermal energy dissipation to minimize photodamage in winter. These mechanisms aid a quick restart of photosynthesis without the development of new leaves in the following spring.

  9. The link between convective organization and extreme precipitation in a warming climate

    NASA Astrophysics Data System (ADS)

    Pendergrass, Angeline

    2016-04-01

    The rate of increase of extreme precipitation in response to global warming varies dramatically across simulations of warming with different climate models, particularly over the tropical oceans, for reasons that have yet to be established. Here, we propose one possible mechanism: changing organization of convection with climate. Recently, self-organization of convection has been studied in global radiative-convective equilibrium climate model simulations. We analyze a set of 20 simulations forced by fixed SSTs at 2 degree increments from 287 to 307 K with the Community Atmosphere Model version 5 (CAM5). In these simulations, a transition from unorganized to organized convection occurs at just over 300 K. Precipitation extremes increase steadily with warming before and after the transition from unorganized to organized states, but at the transition the change in extreme precipitation is much larger. We develop a metric for convective organization in conjunction with the characteristics of extreme precipitation events (defined as events with precipitation over a percentile threshold of daily rainfall accumulation): the number of events, their area, their lifetime, and their mean rainfall, and use this to explore the connection between extreme precipitation and organization. We also apply this metric to CMIP5 simulations to evaluate whether our mechanism has bearing on the range of tropical ocean extreme precipitation response across this set of comprehensive climate models.

  10. Does winter warming enhance cold CO2 emission from temperate continental soils?

    NASA Astrophysics Data System (ADS)

    Kurganova, Irina; Lopes de Gerenyu, Valentin; Khoroshaev, Dmitry

    2016-04-01

    revealed during the early spring FTC. They corresponded to a rapid thawing of frozen soils due to the customary rise of air temperature at the beginning of March. These CO2 emission pulses during early spring contributed between 43% and 70% to the total cold CO2 fluxes from frozen soils ('Ref" and "NoSn" variants). The contribution of spring fluxes from unfrozen soils ("NoFr" treatment) to the total cold CO2 emission was about 25%. Our findings produce evidence that winter warming in temperate continental regions has resulted in a reduction in the permanent snow pack, an increase in the frequency of freezing-thawing events and can be followed by a prolongation of the period when soils remain frozen. Soil respiration fluxes were greatly reduced owing to an increase in frost stress both for plants and for the soil microbial community. Therefore, winter warming in temperate continental areas decreases cold CO2 emissions from soils into the atmosphere and is expected thereby to lead to a rise in the annual carbon sink in ecosystems. This study was supported by the Russian Science Foundation (14-14-00625) and the Russian Foundation for Basic Research (project 15-04-05156a).

  11. Extreme Cold: A Prevention Guide to Promote Your Personal Health and Safety

    MedlinePlus

    ... www.bt.cdc.gov/disasters/winter/ hen winter temperatures drop significantly below normal, staying warm and safe can become a chal- lenge. Extremely cold temperatures often accompany a winter storm, so you may ...

  12. Disease transmission in an extreme environment: nematode parasites infect reindeer during the Arctic winter.

    PubMed

    Carlsson, Anja M; Justin Irvine, R; Wilson, Kenneth; Piertney, Stuart B; Halvorsen, Odd; Coulson, Stephen J; Stien, Audun; Albon, Steve D

    2012-07-01

    Parasitic nematodes are found in almost all wild vertebrate populations but few studies have investigated these host-parasite relationships in the wild. For parasites with free-living stages, the external environment has a major influence on life-history traits, and development and survival is generally low at sub-zero temperatures. For reindeer that inhabit the high Arctic archipelago of Svalbard, parasite transmission is expected to occur in the summer, due to the extreme environmental conditions and the reduced food intake by the host in winter. Here we show experimentally that, contrary to most parasitic nematodes, Marshallagia marshalli of Svalbard reindeer is transmitted during the Arctic winter. Winter transmission was demonstrated by removing parasites in the autumn, using a novel delayed-release anthelmintic bolus, and estimating re-infection rates in reindeer sampled in October, February and April. Larval stages of nematodes were identified using molecular tools, whereas adult stages were identified using microscopy. The abundance of M. marshalli adult worms and L4s increased significantly from October to April, indicating that reindeer were being infected with L3s from the pasture throughout the winter. To our knowledge, this study is the first to experimentally demonstrate over-winter transmission of a gastro-intestinal nematode parasite in a wild animal. Potential mechanisms associated with this unusual transmission strategy are discussed in light of our knowledge of the life-history traits of this parasite.

  13. North Atlantic summers have warmed more than winters since 1353, and the response of marine zooplankton

    PubMed Central

    Kamenos, Nicholas A.

    2010-01-01

    Modeling and measurements show that Atlantic marine temperatures are rising; however, the low temporal resolution of models and restricted spatial resolution of measurements (i) mask regional details critical for determining the rate and extent of climate variability, and (ii) prevent robust determination of climatic impacts on marine ecosystems. To address both issues for the North East Atlantic, a fortnightly resolution marine climate record from 1353–2006 was constructed for shallow inshore waters and compared to changes in marine zooplankton abundance. For the first time summer marine temperatures are shown to have increased nearly twice as much as winter temperatures since 1353. Additional climatic instability began in 1700 characterized by ∼5–65 year climate oscillations that appear to be a recent phenomenon. Enhanced summer-specific warming reduced the abundance of the copepod Calanus finmarchicus, a key food item of cod, and led to significantly lower projected abundances by 2040 than at present. The faster increase of summer marine temperatures has implications for climate projections and affects abundance, and thus biomass, near the base of the marine food web with potentially significant feedback effects for marine food security. PMID:21148422

  14. Response of snow-dependent hydrologic extremes to continued global warming

    PubMed Central

    Diffenbaugh, Noah S.; Scherer, Martin; Ashfaq, Moetasim

    2013-01-01

    Snow accumulation is critical for water availability in the northern hemisphere 1,2, raising concern that global warming could have important impacts on natural and human systems in snow-dependent regions 1,3. Although regional hydrologic changes have been observed (e.g., 1,3–5), the time of emergence of extreme changes in snow accumulation and melt remains a key unknown for assessing climate change impacts 3,6,7. We find that the CMIP5 global climate model ensemble exhibits an imminent shift towards low snow years in the northern hemisphere, with areas of western North America, northeastern Europe, and the Greater Himalaya showing the strongest emergence during the near-term decades and at 2°C global warming. The occurrence of extremely low snow years becomes widespread by the late-21st century, as do the occurrence of extremely high early-season snowmelt and runoff (implying increasing flood risk), and extremely low late-season snowmelt and runoff (implying increasing water stress). Our results suggest that many snow-dependent regions of the northern hemisphere are likely to experience increasing stress from low snow years within the next three decades, and from extreme changes in snow-dominated water resources if global warming exceeds 2°C above the pre-industrial baseline. PMID:24015153

  15. Reproducing under a warming climate: long winter flowering and extended flower longevity in the only Mediterranean and maritime Primula.

    PubMed

    Aronne, G; Buonanno, M; De Micco, V

    2015-03-01

    Under the pressure of global warming, general expectations of species migration and evolution of adaptive traits should always be confirmed with species-specific studies. Within this framework, some species can be used as study systems to predict possible consequences of global warming also on other relatives. Unlike its mountain congeneric, Primula palinuri Petagn. has endured all the climatic fluctuations since the Pleistocene, while surviving on Mediterranean coastal cliffs. The aim of this work was to investigate the possible evolution of reproductive biological and ecological traits in P. palinuri adaptation to a warmer environment. Data showed that flowering starts in mid-winter; single flowers remain open for over a month, changing from pendulous to erect. The number of insects visiting flowers of P. palinuri increases during the flowering season, and pollination reduces flower longevity. Overall, the best pollen performances, in terms of viability and germinability, occur at winter temperatures, while pollinator activity prolongs flowering until spring. Moreover, extended longevity of single flowers optimises reproductive success. Both phenotypic plasticity and selective processes might have occurred in P. palinuri. However, we found that reproductive traits of the only Mediterranean Primula remain more associated with cold mountain habitats than warm coastal cliffs. Given the rapid trend of climate warming, migration and new adaptive processes in P. palinuri are unlikely. Response to past climate warming of P. palinuri provides useful indications for future scenarios in other Primula species.

  16. Effects of Cardamom Mountains on the formation of the winter warm pool in the gulf of Thailand

    NASA Astrophysics Data System (ADS)

    Li, Jiaxun; Zhang, Ren; Ling, Zheng; Bo, Wenbo; Liu, Yuhong

    2014-12-01

    A small-scale winter warm pool covering an area of about 75,000 km2 in the Gulf of Thailand (GoT) was uncovered using a suite of new high resolution satellite observations and historical in situ data. The core temperature of this warm pool is about 0.5-0.8 °C higher than that of the surroundings. The warm pool exists from the surface to the bottom of the sea. It forms in the first ten days of November, evolves to a mature stage from the mid-November to the early in January, and begins to decay in the mid-January. Our results show the formation of the warm pool is well correlated with the Cardamom Mountains on the Indo-China Peninsula. Due to the orographic effect of Cardamom Mountains, the low surface latent heat flux resulting from the wind wake leads to the formation of the warm pool in the sea. The interannual variability of the warm pool is affected by the El Niño-Southern Oscillation (ENSO) by modulating the strength of northeast monsoon each year. The warm pool has a possible implication for the marine ecosystem in the GoT.

  17. Changes in Extremely Hot Summers over the Global Land Area under Various Warming Targets.

    PubMed

    Wang, Lei; Huang, Jianbin; Luo, Yong; Yao, Yao; Zhao, Zongci

    2015-01-01

    Summer temperature extremes over the global land area were investigated by comparing 26 models of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) with observations from the Goddard Institute for Space Studies (GISS) and the Climate Research Unit (CRU). Monthly data of the observations and models were averaged for each season, and statistics were calculated for individual models before averaging them to obtain ensemble means. The summers with temperature anomalies (relative to 1951-1980) exceeding 3σ (σ is based on the local internal variability) are defined as "extremely hot". The models well reproduced the statistical characteristics evolution, and partly captured the spatial distributions of historical summer temperature extremes. If the global mean temperature increases 2°C relative to the pre-industrial level, "extremely hot" summers are projected to occur over nearly 40% of the land area (multi-model ensemble mean projection). Summers that exceed 5σ warming are projected to occur over approximately 10% of the global land area, which were rarely observed during the reference period. Scenarios reaching warming levels of 3°C to 5°C were also analyzed. After exceeding the 5°C warming target, "extremely hot" summers are projected to occur throughout the entire global land area, and summers that exceed 5σ warming would become common over 70% of the land area. In addition, the areas affected by "extremely hot" summers are expected to rapidly expand by more than 25%/°C as the global mean temperature increases by up to 3°C before slowing to less than 16%/°C as the temperature continues to increase by more than 3°C. The area that experiences summers with warming of 5σ or more above the warming target of 2°C is likely to maintain rapid expansion of greater than 17%/°C. To reduce the impacts and damage from severely hot summers, the global mean temperature increase should remain low.

  18. Changes in Extremely Hot Summers over the Global Land Area under Various Warming Targets.

    PubMed

    Wang, Lei; Huang, Jianbin; Luo, Yong; Yao, Yao; Zhao, Zongci

    2015-01-01

    Summer temperature extremes over the global land area were investigated by comparing 26 models of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) with observations from the Goddard Institute for Space Studies (GISS) and the Climate Research Unit (CRU). Monthly data of the observations and models were averaged for each season, and statistics were calculated for individual models before averaging them to obtain ensemble means. The summers with temperature anomalies (relative to 1951-1980) exceeding 3σ (σ is based on the local internal variability) are defined as "extremely hot". The models well reproduced the statistical characteristics evolution, and partly captured the spatial distributions of historical summer temperature extremes. If the global mean temperature increases 2°C relative to the pre-industrial level, "extremely hot" summers are projected to occur over nearly 40% of the land area (multi-model ensemble mean projection). Summers that exceed 5σ warming are projected to occur over approximately 10% of the global land area, which were rarely observed during the reference period. Scenarios reaching warming levels of 3°C to 5°C were also analyzed. After exceeding the 5°C warming target, "extremely hot" summers are projected to occur throughout the entire global land area, and summers that exceed 5σ warming would become common over 70% of the land area. In addition, the areas affected by "extremely hot" summers are expected to rapidly expand by more than 25%/°C as the global mean temperature increases by up to 3°C before slowing to less than 16%/°C as the temperature continues to increase by more than 3°C. The area that experiences summers with warming of 5σ or more above the warming target of 2°C is likely to maintain rapid expansion of greater than 17%/°C. To reduce the impacts and damage from severely hot summers, the global mean temperature increase should remain low. PMID:26090931

  19. Quantifying the influence of observed global warming on the probability of unprecedented extreme climate events

    NASA Astrophysics Data System (ADS)

    Diffenbaugh, N. S.; Rajaratnam, B.; Charland, A.; Haugen, M.; Horton, D. E.; Singh, D.; Swain, D. L.; Tsiang, M.

    2014-12-01

    Now that observed global warming has been clearly attributed to human activities, there has been increasing interest in the extent to which that warming has influenced the occurrence and severity of individual extreme climate events. However, although trends in the extremes of the seasonal- and daily-scale distributions of climate records have been analyzed for many years, quantifying the contribution of observed global warming to individual events that are unprecedented in the observed record presents a particular scientific challenge. We will describe a modified method for leveraging observations and large climate model ensembles to quantify the influence of observed global warming on the probability of unprecedented extreme events. In this approach, we first diagnose the causes of the individual event in order to understand which climate processes to target in the probability quantification. We then use advanced statistical techniques to quantify the uncertainty in the return period of the event in the observed record. We then use large ensembles of climate model simulations to quantify the distribution of return period ratios between the current level of climate forcing and the pre-industrial climate forcing. We will compare the structure of this approach to other approaches that exist in the literature. We will then examine a set of individual extreme events that have been analyzed in the literature, and compare the results of our approach with those that have been previously published. We will conclude with a discussion of the observed agreement and disagreement between the different approaches, including implications for interpretation of the role of human forcing in shaping unprecedented extreme events.

  20. Are winter-active species vulnerable to climate warming? A case study with the wintergreen terrestrial orchid, Tipularia discolor.

    PubMed

    Marchin, Renée M; Dunn, Robert R; Hoffmann, William A

    2014-12-01

    In the eastern United States, winter temperature has been increasing nearly twice as fast as summer temperature, but studies of warming effects on plants have focused on species that are photosynthetically active in summer. The terrestrial orchid Tipularia discolor is leafless in summer and acquires C primarily in winter. The optimum temperature for photosynthesis in T. discolor is higher than the maximum temperature throughout most of its growing season, and therefore growth can be expected to increase with warming. Contrary to this hypothesis, experimental warming negatively affected reproductive fitness (number of flowering stalks, flowers, fruits) and growth (change in leaf area from 2010 to 2012) in T. discolor. Temperature in June-July was critical for flowering, and mean July temperature greater than 29 °C (i.e., 2.5 °C above ambient) eliminated reproduction. Warming of 1.2 °C delayed flowering by an average of 10 days and fruiting by an average of 5 days. Warming of 4.4 °C reduced relative growth rates by about 60%, which may have been partially caused by the direct effects of temperature on photosynthesis and respiration. Warming indirectly increased vapor pressure deficit (VPD) by 0.2-0.5 kPa, and leaf-to-air VPD over 1.3 kPa restricted stomatal conductance of T. discolor to 10-40% of maximum conductance. These results highlight the need to account for changes in VPD when estimating temperature responses of plant species under future warming scenarios. Increasing temperature in the future will likely be an important limiting factor to the distribution of T. discolor, especially along the southern edge of its range.

  1. Arctic sea ice loss and recent extreme cold winter in Eurasia

    NASA Astrophysics Data System (ADS)

    Mori, Masato; Watanabe, Masahiro; Ishii, Masayoshi; Kimoto, Masahide

    2014-05-01

    Extreme cold winter over the Eurasia has occurred more frequently in recent years. Observational evidence in recent studies shows that the wintertime cold anomalies over the Eurasia are associated with decline of Arctic sea ice in preceding autumn to winter season. However, the tropical and/or mid-latitude sea surface temperature (SST) anomalies have great influence on the mid- and high-latitude atmospheric variability, it is difficult to isolate completely the impacts of sea ice change from observational data. In this study, we examine possible linkage between the Arctic sea ice loss and the extreme cold winter over the Eurasia using a state-of-the-art MIROC4 (T106L56) atmospheric general circulation model (AGCM) to assess the pure atmospheric responses to sea ice reduction. We perform two sets of experiments with different realistic sea ice boundary conditions calculated by composite of observed sea ice concentration; one is reduced sea ice extent case (referred to as LICE run) and another is enhanced case (HICE run). In both experiments, the model is integrated 6-month from September to February with 100-member ensemble under the climatological SST boundary condition. The difference in ensemble mean of each experiment (LICE minus HICE) shows cold anomalies over the Eurasia in winter and its spatial pattern is very similar to corresponding observation, though the magnitude is smaller than observation. This result indicates that a part of observed cold anomaly can be attributed to the Arctic sea ice loss. We would like to introduce more important results and mechanisms in detail in my presentation.

  2. A Downturn of the Strong Winter-Warming Trend In Europe

    NASA Technical Reports Server (NTRS)

    Otterman, Joseph; Atlas, Robert; Bungato, Dennis; Koslowsky, Dirk; Wos, Alojzy; Atlas, Robert (Technical Monitor)

    2002-01-01

    Surface-air temperatures measured in winter at 3 meteorological stations in central Europe rise substantially for most of the second-half of the 20th century. This means shorter winter, and longer growing season, which has positive implications for regional agriculture. However, these positive trends stopped in winter of 1996, and for the recent 7 years no further climatic amelioration is reported.

  3. Winter climate extremes and their role for priming SOM decomposition under the snow

    NASA Astrophysics Data System (ADS)

    Gavazov, Konstantin; Bahn, Michael

    2015-04-01

    The central research question of this project is how soil respiration and soil microbial community composition and activity of subalpine grasslands are affected by extreme winter climate events, such as mid-winter snowmelt and subsequent advanced growing season date. In the scope of this talk, focus will be laid on the assumptions that (1) reduced snow cover leads to intensive freeze-thaw cycles in the soil with larger amplitudes of microbial biomass, DOC and soil CO2 production and efflux over the course of winter, and shifts peak microbial activity to deeper soil layers with limited and recalcitrant substrate; (2) causes a shift in microbial community composition towards decreased fungal/bacterial ratios; and (3) results in a stronger incorporation of labile C in microbial biomass and more pronounced priming effects of soil organic matter turnover. Our findings indicate that snow removal, induces a strong and immediate negative effect on the physiology of soil microbes, impairing them in their capacity for turnover of SOM in the presence of labile substances (priming). This effect however is transient and soil microbes recover within the same winter. The reason for that is that snow removal did not produce any measurable (PLFA) changes in soil microbial community composition. The advanced start of the growing season, as a result of snow removal in mid-winter, granted the bacterial part of the microbial community more active in the uptake of labile substrates and the turnover of SOM than the fungal one. This finding is in line with the concept for a seasonal shift towards bacterial-dominated summer microbial community composition and could bring about implications for the plant-microbe competition for resources at the onset of the growing season.

  4. Response of snow-dependent hydrologic extremes to continued global warming

    SciTech Connect

    Diffenbaugh, Noah; Scherer, Martin; Ashfaq, Moetasim

    2012-01-01

    Snow accumulation is critical for water availability in the Northern Hemisphere1,2, raising concern that global warming could have important impacts on natural and human systems in snow-dependent regions1,3. Although regional hydrologic changes have been observed (for example, refs 1,3 5), the time of emergence of extreme changes in snow accumulation and melt remains a key unknown for assessing climate- change impacts3,6,7. We find that the CMIP5 global climate model ensemble exhibits an imminent shift towards low snow years in the Northern Hemisphere, with areas of western North America, northeastern Europe and the Greater Himalaya showing the strongest emergence during the near- termdecadesandat2 Cglobalwarming.Theoccurrenceof extremely low snow years becomes widespread by the late twenty-first century, as do the occurrences of extremely high early-season snowmelt and runoff (implying increasing flood risk), and extremely low late-season snowmelt and runoff (implying increasing water stress). Our results suggest that many snow-dependent regions of the Northern Hemisphere are likely to experience increasing stress from low snow years within the next three decades, and from extreme changes in snow-dominated water resources if global warming exceeds 2 C above the pre-industrial baseline.

  5. Link between warm conveyor belts and fronts and the impact on extreme rainfall

    NASA Astrophysics Data System (ADS)

    Catto, Jennifer; Madonna, Erica; Joos, Hanna; Wernli, Heini; Rudeva, Irina; Simmonds, Ian

    2015-04-01

    The various dynamical features within extratropical cyclones have been shown to be very important for the precipitation produced by these systems. Warm conveyor belts (WCBs) and fronts are both strongly associated with total and extreme precipitation in the midlatitudes. Here we have brought together two automated feature detection methods to answer questions on the frequency of matching of fronts and WCBs, whether this depends on frontal type or height of WCB, and the impact this matching has on extreme precipitation events. We find that WCBs and fronts are strongly related in the midlatitudes - annually 60% of WCBs are associated with cold fronts and around 50% associated with warm fronts, and a fairly large proportion associated with both together. The frequency of linked WCBs and fronts shows a strong seasonal cycle. In some regions warm fronts are more strongly linked to WCBs than cold fronts. To the east of Australia in particular, there are often WCBs not associated with fronts at all. Fronts that co-occur with a WCB are much more likely to produce an extreme precipitation event.

  6. Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015.

    PubMed

    Sun, Yele; Chen, Chen; Zhang, Yingjie; Xu, Weiqi; Zhou, Libo; Cheng, Xueling; Zheng, Haitao; Ji, Dongsheng; Li, Jie; Tang, Xiao; Fu, Pingqing; Wang, Zifa

    2016-01-01

    We investigate the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze episode that occurred in northern China during winter 2015 using comprehensive ground and vertical measurements, along with receptor and dispersion model analysis. Our results indicate that the life cycle of a severe winter haze episode typically consists of four stages: (1) rapid formation initiated by sudden changes in meteorological parameters and synchronous increases in most aerosol species, (2) persistent evolution with relatively constant variations in secondary inorganic aerosols and secondary organic aerosols, (3) further evolution associated with fog processing and significantly enhanced sulfate levels, and (4) clearing due to dry, cold north-northwesterly winds. Aerosol composition showed substantial changes during the formation and evolution of the haze episode but was generally dominated by regional secondary aerosols (53-67%). Our results demonstrate the important role of regional transport, largely from the southwest but also from the east, and of coal combustion emissions for winter haze formation in Beijing. Also, we observed an important downward mixing pathway during the severe haze in 2015 that can lead to rapid increases in certain aerosol species. PMID:27243909

  7. Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015

    PubMed Central

    Sun, Yele; Chen, Chen; Zhang, Yingjie; Xu, Weiqi; Zhou, Libo; Cheng, Xueling; Zheng, Haitao; Ji, Dongsheng; Li, Jie; Tang, Xiao; Fu, Pingqing; Wang, Zifa

    2016-01-01

    We investigate the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze episode that occurred in northern China during winter 2015 using comprehensive ground and vertical measurements, along with receptor and dispersion model analysis. Our results indicate that the life cycle of a severe winter haze episode typically consists of four stages: (1) rapid formation initiated by sudden changes in meteorological parameters and synchronous increases in most aerosol species, (2) persistent evolution with relatively constant variations in secondary inorganic aerosols and secondary organic aerosols, (3) further evolution associated with fog processing and significantly enhanced sulfate levels, and (4) clearing due to dry, cold north-northwesterly winds. Aerosol composition showed substantial changes during the formation and evolution of the haze episode but was generally dominated by regional secondary aerosols (53–67%). Our results demonstrate the important role of regional transport, largely from the southwest but also from the east, and of coal combustion emissions for winter haze formation in Beijing. Also, we observed an important downward mixing pathway during the severe haze in 2015 that can lead to rapid increases in certain aerosol species. PMID:27243909

  8. Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015.

    PubMed

    Sun, Yele; Chen, Chen; Zhang, Yingjie; Xu, Weiqi; Zhou, Libo; Cheng, Xueling; Zheng, Haitao; Ji, Dongsheng; Li, Jie; Tang, Xiao; Fu, Pingqing; Wang, Zifa

    2016-05-31

    We investigate the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze episode that occurred in northern China during winter 2015 using comprehensive ground and vertical measurements, along with receptor and dispersion model analysis. Our results indicate that the life cycle of a severe winter haze episode typically consists of four stages: (1) rapid formation initiated by sudden changes in meteorological parameters and synchronous increases in most aerosol species, (2) persistent evolution with relatively constant variations in secondary inorganic aerosols and secondary organic aerosols, (3) further evolution associated with fog processing and significantly enhanced sulfate levels, and (4) clearing due to dry, cold north-northwesterly winds. Aerosol composition showed substantial changes during the formation and evolution of the haze episode but was generally dominated by regional secondary aerosols (53-67%). Our results demonstrate the important role of regional transport, largely from the southwest but also from the east, and of coal combustion emissions for winter haze formation in Beijing. Also, we observed an important downward mixing pathway during the severe haze in 2015 that can lead to rapid increases in certain aerosol species.

  9. Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015

    NASA Astrophysics Data System (ADS)

    Sun, Yele; Chen, Chen; Zhang, Yingjie; Xu, Weiqi; Zhou, Libo; Cheng, Xueling; Zheng, Haitao; Ji, Dongsheng; Li, Jie; Tang, Xiao; Fu, Pingqing; Wang, Zifa

    2016-05-01

    We investigate the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze episode that occurred in northern China during winter 2015 using comprehensive ground and vertical measurements, along with receptor and dispersion model analysis. Our results indicate that the life cycle of a severe winter haze episode typically consists of four stages: (1) rapid formation initiated by sudden changes in meteorological parameters and synchronous increases in most aerosol species, (2) persistent evolution with relatively constant variations in secondary inorganic aerosols and secondary organic aerosols, (3) further evolution associated with fog processing and significantly enhanced sulfate levels, and (4) clearing due to dry, cold north-northwesterly winds. Aerosol composition showed substantial changes during the formation and evolution of the haze episode but was generally dominated by regional secondary aerosols (53–67%). Our results demonstrate the important role of regional transport, largely from the southwest but also from the east, and of coal combustion emissions for winter haze formation in Beijing. Also, we observed an important downward mixing pathway during the severe haze in 2015 that can lead to rapid increases in certain aerosol species.

  10. Net nitrogen mineralization and leaching in response to warming and nitrogen deposition in a temperate old field: the importance of winter temperature.

    PubMed

    Turner, Michelle M; Henry, Hugh A L

    2010-01-01

    While climate warming can increase plant N availability over the growing season by increasing rates of N mineralization, increased N mineralization over winter at a time when plant roots are largely inactive, coupled with an increased frequency of soil freeze-thaw cycles, may increase soil N leaching losses. We examined changes in soil net N mineralization and N leaching in response to warming and N addition (6 g m(-2) year(-1)) in a factorial experiment conducted in a temperate old field. We used two warming treatments, year-round and winter-only warming, to isolate the effects of winter warming on soil N dynamics from the year-round warming effects. We estimated net N mineralization using in situ soil cores with resin bags placed at the bottom to catch throughput, and we measured N leaching using lysimeters located below the plant rooting zone at a depth of 50 cm. There were minor effects of warming on changes in soil extractable N and resin N in the soil cores over winter. Nevertheless, the overall effects of both warming and N addition on net N mineralization (the sum of changes in soil extractable N and resin N) were not significant over this period. Likewise, there were no significant treatment effects on the concentration of N in leachate collected below the plant rooting zone. However, in response to winter warming, net N mineralization over summer was approximately double that of both the ambient and year-round warming treatments. This result demonstrates a potentially large and unexpected effect of winter warming on soil N availability in this old field system. PMID:19690892

  11. Intensity, duration, and frequency of precipitation extremes under 21st-century warming scenarios

    SciTech Connect

    Kao, Shih-Chieh; Ganguly, Auroop R

    2011-01-01

    Recent research on the projection of precipitation extremes has either focused on conceptual physical mechanisms that generate heavy precipitation or rigorous statistical methods that extrapolate tail behavior. However, informing both climate prediction and impact assessment requires concurrent physically and statistically oriented analysis. A combined examination of climate model simulations and observation-based reanalysis data sets suggests more intense and frequent precipitation extremes under 21st-century warming scenarios. Utilization of statistical extreme value theory and resampling-based uncertainty quantification combined with consideration of the Clausius-Clapeyron relationship reveals consistently intensifying trends for precipitation extremes at a global-average scale. However, regional and decadal analyses reveal specific discrepancies in the physical mechanisms governing precipitation extremes, as well as their statistical trends, especially in the tropics. The intensifying trend of precipitation extremes has quantifiable impacts on intensity-duration-frequency curves, which in turn have direct implications for hydraulic engineering design and water-resources management. The larger uncertainties at regional and decadal scales suggest the need for caution during regional-scale adaptation or preparedness decisions. Future research needs to explore the possibility of uncertainty reduction through higher resolution global climate models, statistical or dynamical downscaling, as well as improved understanding of precipitation extremes processes.

  12. Attributing extreme precipitation in the Black Sea region to sea surface warming

    NASA Astrophysics Data System (ADS)

    Meredith, Edmund; Semenov, Vladimir; Maraun, Douglas; Park, Wonsun; Chernokulsky, Alexander

    2016-04-01

    Higher sea surface temperatures (SSTs) warm and moisten the overlying atmosphere, increasing the low-level atmospheric instability, the moisture available to precipitating systems and, hence, the potential for intense convective systems. Both the Mediterranean and Black Sea regions have seen a steady increase in summertime SSTs since the early 1980s, by over 2 K in places. This raises the question of how this SST increase has affected convective precipitation extremes in the region, and through which mechanisms any effects are manifested. In particular, the Black Sea town of Krymsk suffered an unprecedented precipitation extreme in July 2012, which may have been influenced by Black Sea warming, causing over 170 deaths. To address this question, we adopt two distinct modelling approaches to event attribution and compare their relative merits. In the first, we use the traditional probabilistic event attribution approach involving global climate model ensembles representative of the present and a counterfactual past climate where regional SSTs have not increased. In the second, we use the conditional event attribution approach, taking the 2012 Krymsk precipitation extreme as a showcase example. Under the second approach, we carry out ensemble sensitivity experiments of the Krymsk event at convection-permitting resolution with the WRF regional model, and test the sensitivity of the event to a range of SST forcings. Both experiments show the crucial role of recent Black Sea warming in amplifying the 2012 Krymsk precipitation extreme. In the conditional event attribution approach, though, the explicit simulation of convective processes provides detailed insight into the physical mechanisms behind the extremeness of the event, revealing the dominant role of dynamical (i.e. static stability and vertical motions) over thermodynamical (i.e. increased atmospheric moisture) changes. Additionally, the wide range of SST states tested in the regional setup, which would be

  13. Soccer-Specific Warm-Up and Lower Extremity Injury Rates in Collegiate Male Soccer Players

    PubMed Central

    Grooms, Dustin R.; Palmer, Thomas; Onate, James A.; Myer, Gregory D.; Grindstaff, Terry

    2013-01-01

    Context: A number of comprehensive injury-prevention programs have demonstrated injury risk-reduction effects but have had limited adoption across athletic settings. This may be due to program noncompliance, minimal exercise supervision, lack of exercise progression, and sport specificity. A soccer-specific program described as the F-MARC 11+ was developed by an expert group in association with the Federation Internationale de Football Association (FIFA) Medical Assessment and Research Centre (F-MARC) to require minimal equipment and implementation as part of regular soccer training. The F-MARC 11+ has been shown to reduce injury risk in youth female soccer players but has not been evaluated in an American male collegiate population. Objective: To investigate the effects of a soccer-specific warm-up program (F-MARC 11+) on lower extremity injury incidence in male collegiate soccer players. Design: Cohort study. Setting: One American collegiate soccer team followed for 2 seasons. Patients or Other Participants: Forty-one male collegiate athletes aged 18–25 years. Intervention(s): The F-MARC 11+ program is a comprehensive warm-up program targeting muscular strength, body kinesthetic awareness, and neuromuscular control during static and dynamic movements. Training sessions and program progression were monitored by a certified athletic trainer. Main Outcome Measure(s): Lower extremity injury risk and time lost to lower extremity injury. Results: The injury rate in the referent season was 8.1 injuries per 1000 exposures with 291 days lost and 2.2 injuries per 1000 exposures and 52 days lost in the intervention season. The intervention season had reductions in the relative risk (RR) of lower extremity injury of 72% (RR = 0.28, 95% confidence interval = 0.09, 0.85) and time lost to lower extremity injury (P < .01). Conclusions: This F-MARC 11+ program reduced overall risk and severity of lower extremity injury compared with controls in collegiate-aged male soccer

  14. The influence of atmospheric blocking on extreme winter minimum temperatures in North America

    NASA Astrophysics Data System (ADS)

    Whan, Kirien; Zwiers, Francis; Sillmann, Jana

    2016-04-01

    Regional climate models (RCMs) are the primary source of high-resolution climate projections and it is of crucial importance to evaluate their ability to simulate extreme events under current climate conditions. Many extreme events are influenced by circulation features that occur outside, or on the edges of, RCM domains. Thus it is of interest to know whether such dynamically controlled aspects of extremes are well represented by RCMs. This study assesses the relationship between upstream blocking and cold temperature extremes over North America in observations, reanalysis products (ERA-Interim, NARR) and RCMs (CanRCM4, CRCM5, HIRHAM5, RCA4). Generalized extreme value distributions were fitted to winter minimum temperature (TNn) incorporating blocking frequency (BF) as a covariate, which has a significant influence on TNn. The magnitude of blocking influence in the RCMs is consistent with observations but the spatial extent varies. CRCM5 and HIRHAM5 reproduce the pattern of influence best compared to observations. CanRCM4 and RCA4 capture the influence of blocking in British Columbia and the northeastern United States but the extension of influence that is seen in observations and reanalysis, into the southern United States is not evident. The difference in the 20-year return value (20RV) of TNn between high and low BF indicates that blocking is associated with a decrease of up to 15°C in the 20RV over the majority of the United States and in western Canada. In northern North America the difference in the 20RV is positive as blocking is associated with warmer temperatures. The 20RVs are generally simulated well by the RCMs.

  15. Impact of the Extreme Warming of 2012 on Shelfbreak Frontal Structure North of Cape Hatteras

    NASA Astrophysics Data System (ADS)

    Gawarkiewickz, G.

    2014-12-01

    Continental shelf circulation north of Cape Hatteras is complex, with southward flowing Middle Atlantic Bight shelf water intersecting the Gulf Stream and subducting offshore into the Gulf Stream. In May, 2012, a cruise was conducted in order to study the shelf circulation and acoustic propagation through fish schools in the area. An important aspect of the study was to use Autonomous Underwater Vehicles to map fish schools with a sidescan sonar. High-resolution hydrographic surveys to map the continental shelf water masses and shelfbreak frontal structure were sampled to relate oceanographic conditions to the fish school distributions. The cold pool water mass over the continental shelf in May 2012 was extremely warm, with temperature anomalies of up to 5 Degrees C relative to observations from the same area in May, 1996. The normal cross-shelf temperature gradients within the shelfbreak front were not present because of the warming. As a result, the shelf density field was much more buoyant than usual, which led to an accelerated shelfbreak jet. Moored velocity measurements at the 60 m isobath recorded alongshelf flow of as much as 0.6 m/s. The anticipated fish species were not observed over the continental shelf. Some comments on the forcing leading to the large scale warming will be presented, along with a brief discussion of the impact of the warming on the marine ecosystem in the northeast U.S.

  16. The extreme Northern Hemisphere winter of 2013/4: The role of tropical SSTs

    NASA Astrophysics Data System (ADS)

    Watson, Peter; Knight, Jeff; Weisheimer, Antje; Palmer, Tim

    2015-04-01

    The winter of 2013/4 stood out for its extreme cold weather in eastern North America and very strong North Atlantic jet stream, bringing severe flooding to the UK in particular. The extreme weather was not confidently forecast by any seasonal prediction system, begging the question of whether there was any remote driver that could have been used to improve the forecasts, and whether the numerical models used are deficient in some important way. We analyse in particular the role of tropical sea surface temperatures (SSTs). We show that, in both the ECMWF and Met Office forecast models, imposing the positive SST anomalies that were present in the tropical west Pacific causes cold anomalies in eastern North America, through a teleconnection mediated by a Rossby wave train. This indicates that these SST anomalies had a role in causing the extreme American weather. Results from further sets of model ensembles will be presented to show additional significant influences from Tropical Atlantic and Indian Ocean SST anomalies.

  17. Warm-season diurnal circulations and heat extremes over the northwest U.S

    NASA Astrophysics Data System (ADS)

    Brewer, Matthew C.

    Summer synoptic circulations over the northwest U.S., and their interactions with regional terrain, land/water contrasts, and surface heating, give rise to a variety of fascinating meteorological phenomena, many of which have yet to be explored. Furthermore, it is largely unknown how projected future warming associated with increased greenhouse gases will modify these important features. The work herein seeks to ameliorate this with a comprehensive examination of two important aspects of northwest U.S. summer weather and climate: diurnal circulations and changes to the conditions associated with extreme temperatures under anthropogenic global warming. To simulate regional diurnal circulations, GFS model output was obtained for July and August 2009-2011. These data were categorized into hour of the day, composited, and the resulting files were used to initialize and provide boundary conditions to a WRF (version 3.5) model run. It was shown that, when compared to observations, this WRF run sufficiently simulates average diurnal variability. Using this simulation, the diurnal circulations of the region were described, including several important wind features within the Strait of Juan de Fuca, the Snoqualmie Pass, and the Columbia River Gorge. Also, regional nocturnal low-level wind maxima are described, including one over the northern Willamette valley and another over the high plateau of eastern Oregon. Recent work by the authors has elucidated the physical mechanisms that drive heat extremes over the northwest U.S., including the necessity of a ridge aloft, with associated subsidence and advection warming. Also, easterly flow is crucial for keeping the marine air at bay, and producing downslope flow and adiabatic warming on the western slopes of regional north-south terrain barriers. Given the rising temperatures projected under anthropogenic global warming, how are these conditions, and associated low-level temperature distributions, projected to change? As a

  18. Increasing contrasts between wet and dry precipitation extremes during the "global warming hiatus" (1998-2013)

    NASA Astrophysics Data System (ADS)

    Lau, W. K. M.; Wu, H. T.

    2015-12-01

    We investigate changes in daily precipitation extremes using TRMM data (1998-2013), which coincides with the so-called "global warming hiatus". Results show a structural change in probability distribution functions (pdf) of local precipitation events (LPE) during this period, indicating more intense LPE, less moderate LPE, and more dry (no-rain) days globally. Analyses for land and ocean separately reveal more complex and nuanced changes over land, characterized by a strong positive trend (+12.0% per decade, 99% confidence level (c.l.)) in frequency of extreme LPE's over the Northern Hemisphere extratropics during the wet season, but a negative global trend (-6.6% per decade, 95% c.l.) during the dry season. Analyses of the risk of drought based on the number of dry days show a significant global drying trend (3.2% per decade, 99% c.l.) over land during the dry season. Regions of pronounced increased drought include western and central US, northeastern Asia and southern Europe/Mediterranean. Trends in cloud distributions from TRMM VIS-IR, and relative humidity from reanalysis have also been examined. Overall, the changes in water cycle parameters are consistent with increasing contrasts between wet and dry precipitation extremes, as reported in previous studies based on observations and climate model projections for a longer period, implying changes in global water cycle was underway during 1998-2013 as if there is no "global warming hiatus". The implications of the present results will be discussed.

  19. Role of Sea Surface Warming in Triggering Amplification of Coastal Rainfall Extremes

    NASA Astrophysics Data System (ADS)

    Meredith, Edmund; Semenov, Vladimir; Maraun, Douglas; Park, Wonsun; Chernokulsky, Alexander

    2015-04-01

    Whether recent changes in the occurrence of meteorological extremes are attributable to a warmer climate remains a challenging question. One area where the potential for extreme summertime convective precipitation has grown recently, along with substantial sea surface temperature (SST) increase, is the Black Sea and Mediterranean (BSM) region. To study mechanisms through which SST increase may impact BSM convective extremes, we take the July 2012 precipitation extreme near the Black Sea town of Krymsk as a recent showcase example. The event was related to a slow moving low pressure system crossing the eastern Black Sea, advecting warm and moist air towards the coast. Two waves of convection resulted in precipitation totals that dwarfed all previous events in the instrumental record, dating back to the 1930s, and over 170 deaths. The synoptic environment which led to this event is typical of that found with intense summertime precipitation in the BSM region. We carry out ensemble sensitivity experiments over an eastern Black Sea domain with the WRF regional model, using multiply nested sub-domains, increasing to 600 m convection resolving resolution. The model's ability to reproduce the event with observed SST forcing is first verified, before a series of additional ensembles with altered SST is created. These ensembles consist of subtracting (adding) the 1982 - 2012 trend in Black Sea SST from (to) the observed 2012 SST field in 20% increments, giving a total of 11 ensembles whose SST differ from the observed field by between -100% and +100% of the warming trend. We demonstrate that such an intense precipitation event would not have been possible without the recent Black Sea warming. The increased SST enhances low-level instability, allowing deep convection to be triggered and causing a more than 300% increase in precipitation. Additionally, a highly nonlinear precipitation response to incrementally increasing SST suggests that Black Sea SSTs have exceeded a

  20. Increased frequency of extreme Indian Ocean Dipole events due to greenhouse warming.

    PubMed

    Cai, Wenju; Santoso, Agus; Wang, Guojian; Weller, Evan; Wu, Lixin; Ashok, Karumuri; Masumoto, Yukio; Yamagata, Toshio

    2014-06-12

    The Indian Ocean dipole is a prominent mode of coupled ocean-atmosphere variability, affecting the lives of millions of people in Indian Ocean rim countries. In its positive phase, sea surface temperatures are lower than normal off the Sumatra-Java coast, but higher in the western tropical Indian Ocean. During the extreme positive-IOD (pIOD) events of 1961, 1994 and 1997, the eastern cooling strengthened and extended westward along the equatorial Indian Ocean through strong reversal of both the mean westerly winds and the associated eastward-flowing upper ocean currents. This created anomalously dry conditions from the eastern to the central Indian Ocean along the Equator and atmospheric convergence farther west, leading to catastrophic floods in eastern tropical African countries but devastating droughts in eastern Indian Ocean rim countries. Despite these serious consequences, the response of pIOD events to greenhouse warming is unknown. Here, using an ensemble of climate models forced by a scenario of high greenhouse gas emissions (Representative Concentration Pathway 8.5), we project that the frequency of extreme pIOD events will increase by almost a factor of three, from one event every 17.3 years over the twentieth century to one event every 6.3 years over the twenty-first century. We find that a mean state change--with weakening of both equatorial westerly winds and eastward oceanic currents in association with a faster warming in the western than the eastern equatorial Indian Ocean--facilitates more frequent occurrences of wind and oceanic current reversal. This leads to more frequent extreme pIOD events, suggesting an increasing frequency of extreme climate and weather events in regions affected by the pIOD.

  1. Increased frequency of extreme Indian Ocean Dipole events due to greenhouse warming.

    PubMed

    Cai, Wenju; Santoso, Agus; Wang, Guojian; Weller, Evan; Wu, Lixin; Ashok, Karumuri; Masumoto, Yukio; Yamagata, Toshio

    2014-06-12

    The Indian Ocean dipole is a prominent mode of coupled ocean-atmosphere variability, affecting the lives of millions of people in Indian Ocean rim countries. In its positive phase, sea surface temperatures are lower than normal off the Sumatra-Java coast, but higher in the western tropical Indian Ocean. During the extreme positive-IOD (pIOD) events of 1961, 1994 and 1997, the eastern cooling strengthened and extended westward along the equatorial Indian Ocean through strong reversal of both the mean westerly winds and the associated eastward-flowing upper ocean currents. This created anomalously dry conditions from the eastern to the central Indian Ocean along the Equator and atmospheric convergence farther west, leading to catastrophic floods in eastern tropical African countries but devastating droughts in eastern Indian Ocean rim countries. Despite these serious consequences, the response of pIOD events to greenhouse warming is unknown. Here, using an ensemble of climate models forced by a scenario of high greenhouse gas emissions (Representative Concentration Pathway 8.5), we project that the frequency of extreme pIOD events will increase by almost a factor of three, from one event every 17.3 years over the twentieth century to one event every 6.3 years over the twenty-first century. We find that a mean state change--with weakening of both equatorial westerly winds and eastward oceanic currents in association with a faster warming in the western than the eastern equatorial Indian Ocean--facilitates more frequent occurrences of wind and oceanic current reversal. This leads to more frequent extreme pIOD events, suggesting an increasing frequency of extreme climate and weather events in regions affected by the pIOD. PMID:24919920

  2. Differential impacts of ocean acidification and warming on winter and summer progeny of a coastal squid (Loligo vulgaris).

    PubMed

    Rosa, Rui; Trübenbach, Katja; Pimentel, Marta S; Boavida-Portugal, Joana; Faleiro, Filipa; Baptista, Miguel; Dionísio, Gisela; Calado, Ricardo; Pörtner, Hans O; Repolho, Tiago

    2014-02-15

    Little is known about the capacity of early life stages to undergo hypercapnic and thermal acclimation under the future scenarios of ocean acidification and warming. Here, we investigated a comprehensive set of biological responses to these climate change-related variables (2°C above winter and summer average spawning temperatures and ΔpH=0.5 units) during the early ontogeny of the squid Loligo vulgaris. Embryo survival rates ranged from 92% to 96% under present-day temperature (13-17°C) and pH (8.0) scenarios. Yet, ocean acidification (pH 7.5) and summer warming (19°C) led to a significant drop in the survival rates of summer embryos (47%, P<0.05). The embryonic period was shortened by increasing temperature in both pH treatments (P<0.05). Embryo growth rates increased significantly with temperature under present-day scenarios, but there was a significant trend reversal under future summer warming conditions (P<0.05). Besides pronounced premature hatching, a higher percentage of abnormalities was found in summer embryos exposed to future warming and lower pH (P<0.05). Under the hypercapnic scenario, oxygen consumption rates decreased significantly in late embryos and newly hatched paralarvae, especially in the summer period (P<0.05). Concomitantly, there was a significant enhancement of the heat shock response (HSP70/HSC70) with warming in both pH treatments and developmental stages. Upper thermal tolerance limits were positively influenced by acclimation temperature, and such thresholds were significantly higher in late embryos than in hatchlings under present-day conditions (P<0.05). In contrast, the upper thermal tolerance limits under hypercapnia were higher in hatchlings than in embryos. Thus, we show that the stressful abiotic conditions inside the embryo's capsules will be exacerbated under near-future ocean acidification and summer warming scenarios. The occurrence of prolonged embryogenesis along with lowered thermal tolerance limits under such

  3. Areas of potential suitability and survival of Dendroctonus valens in China under extreme climate warming scenario.

    PubMed

    He, S Y; Ge, X Z; Wang, T; Wen, J B; Zong, S X

    2015-08-01

    The areas in China with climates suitable for the potential distribution of the pest species red turpentine beetle (RTB) Dendroctonus valens LeConte (Coleoptera: Scolytidae) were predicted by CLIMEX based on historical climate data and future climate data with warming estimated. The model used a historical climate data set (1971-2000) and a simulated climate data set (2010-2039) provided by the Tyndall Centre for Climate Change (TYN SC 2.0). Based on the historical climate data, a wide area was available in China with a suitable climate for the beetle in which every province might contain suitable habitats for this pest, particularly all of the southern provinces. The northern limit of the distribution of the beetle was predicted to reach Yakeshi and Elunchun in Inner Mongolia, and the western boundary would reach to Keerkezi in Xinjiang Province. Based on a global-warming scenario, the area with a potential climate suited to RTB in the next 30 years (2010-2039) may extend further to the northeast. The northern limit of the distribution could reach most parts of south Heilongjiang Province, whereas the western limit would remain unchanged. Combined with the tendency for RTB to spread, the variation in suitable habitats within the scenario of extreme climate warming and the multiple geographical elements of China led us to assume that, within the next 30 years, RTB would spread towards the northeast, northwest, and central regions of China and could be a potentially serious problem for the forests of China.

  4. The "warm" Marine Isotope Stage 31 in the Labrador Sea: Low surface salinities and cold subsurface waters prevented winter convection

    NASA Astrophysics Data System (ADS)

    Aubry, A. M. R.; Vernal, A.; Hillaire-Marcel, C.

    2016-09-01

    Surface and subsurface conditions in the Labrador Sea during Marine Isotope Stage (MIS) 31 at the Integrated Ocean Drilling Program Site U1305 off southwest Greenland are reconstructed based on dinocyst and foraminifer assemblages. Isotopic compositions of planktonic (Neogloboquadrina pachyderma, Np) and benthic (Cibicides wuellerstorfi, Cw, and Oridorsalis umbonatus, Ou) foraminifera provide further information about water properties in the mesopelagic layer as well as at the seafloor. Dinocyst proxy reconstructions indicate low salinities (32-34.5), cool winters (3-6°C), and mild summers (10-15°C) in the surface water layer during the MIS 31 "optimum". However, planktonic foraminifer assemblages largely dominated by Np suggest relatively cold subsurface conditions in winter and summer (<4°C). Lower δ13C values in Np versus Cw further suggest either a lesser-ventilated mesopelagic layer than the bottom one or high organic matter oxidation rates at Np habitat depth. The dinocyst and planktonic foraminifer records together suggest a strong stratification between the surface and subsurface water layers. Isotopic and micropaleontological data thus converge toward paleoceanographical conditions unsuitable for convection and intermediate or deep water formation in the Labrador Sea during the warm MIS 31 interglacial, a situation comparable to the one that prevailed during the warm MIS 5e.

  5. The influence of tropical forcing on extreme winter precipitation in the western Himalaya

    NASA Astrophysics Data System (ADS)

    Cannon, Forest; Carvalho, Leila M. V.; Jones, Charles; Hoell, Andrew; Norris, Jesse; Kiladis, George N.; Tahir, Adnan A.

    2016-04-01

    Within the Karakoram and western Himalaya (KH), snowfall from winter westerly disturbances (WD) maintains the region's snowpack and glaciers, which melt seasonally to sustain water resources for downstream populations. WD activity and subsequent precipitation are influenced by global atmospheric variability and tropical-extratropical interactions. On interannual time-scales, El Niño related changes in tropical diabatic heating induce a Rossby wave response over southwest Asia that is linked with enhanced dynamical forcing of WD and available moisture. Consequently, extreme orographic precipitation events are more frequent during El Niño than La Niña or neutral conditions. A similar spatial pattern of tropical diabatic heating is produced by the MJO at intraseasonal scales. In comparison to El Niño, the Rossby wave response to MJO activity is less spatially uniform over southwest Asia and varies on shorter time-scales. This study finds that the MJO's relationship with WD and KH precipitation is more complex than that of ENSO. Phases of the MJO propagation cycle that favor the dynamical enhancement of WD simultaneously suppress available moisture over southwest Asia, and vice versa. As a result, extreme precipitation events in the KH occur with similar frequency in most phases of the MJO, however, there is a transition in the relative importance of dynamical forcing and moisture in WD to orographic precipitation in the KH as the MJO evolves. These findings give insight into the dynamics and predictability of extreme precipitation events in the KH through their relationship with global atmospheric variability, and are an important consideration in evaluating Asia's water resources.

  6. Simulated austral winter response of the Hadley circulation and stationary Rossby wave propagation to a warming climate

    NASA Astrophysics Data System (ADS)

    Freitas, Ana C. V.; Frederiksen, Jorgen S.; O'Kane, Terence J.; Ambrizzi, Tércio

    2016-09-01

    Ensemble simulations, using both coupled ocean-atmosphere (AOGCM) and atmosphere only (AGCM) general circulation models, are employed to examine the austral winter response of the Hadley circulation (HC) and stationary Rossby wave propagation (SRW) to a warming climate. Changes in the strength and width of the HC are firstly examined in a set of runs with idealized sea surface temperature (SST) perturbations as boundary conditions in the AGCM. Strong and weak SST gradient experiments (SG and WG, respectively) simulate changes in the HC intensity, whereas narrow (5°S-5°N) and wide (30°S-30°N) SST warming experiments simulate changes in the HC width. To examine the combined impact of changes in the strength and width of the HC upon SRW propagation two AOGCM simulations using different scenarios of increasing carbon dioxide (CO2) concentrations are employed. We show that, in contrast to a wide SST warming, the atmospheric simulations with a narrow SST warming produce stronger and very zonally extended Rossby wave sources, leading to stronger and eastward shifted troughs and ridges. Simulations with SST anomalies, either in narrow or wide latitude bands only modify the intensity of the troughs and ridges. SST anomalies outside the narrow latitude band of 5°S-5°N do not significantly affect the spatial pattern of SRW propagation. AOGCM simulations with 1 %/year increasing CO2 concentrations or 4 times preindustrial CO2 levels reveal very similar SRW responses to the atmospheric only simulations with anomalously wider SST warming. Our results suggest that in a warmer climate, the changes in the strength and width of the HC act in concert to significantly alter SRW sources and propagation characteristics.

  7. Past extreme warming events linked to massive carbon release from thawing permafrost.

    PubMed

    DeConto, Robert M; Galeotti, Simone; Pagani, Mark; Tracy, David; Schaefer, Kevin; Zhang, Tingjun; Pollard, David; Beerling, David J

    2012-04-01

    Between about 55.5 and 52 million years ago, Earth experienced a series of sudden and extreme global warming events (hyperthermals) superimposed on a long-term warming trend. The first and largest of these events, the Palaeocene-Eocene Thermal Maximum (PETM), is characterized by a massive input of carbon, ocean acidification and an increase in global temperature of about 5 °C within a few thousand years. Although various explanations for the PETM have been proposed, a satisfactory model that accounts for the source, magnitude and timing of carbon release at the PETM and successive hyperthermals remains elusive. Here we use a new astronomically calibrated cyclostratigraphic record from central Italy to show that the Early Eocene hyperthermals occurred during orbits with a combination of high eccentricity and high obliquity. Corresponding climate-ecosystem-soil simulations accounting for rising concentrations of background greenhouse gases and orbital forcing show that the magnitude and timing of the PETM and subsequent hyperthermals can be explained by the orbitally triggered decomposition of soil organic carbon in circum-Arctic and Antarctic terrestrial permafrost. This massive carbon reservoir had the potential to repeatedly release thousands of petagrams (10(15) grams) of carbon to the atmosphere-ocean system, once a long-term warming threshold had been reached just before the PETM. Replenishment of permafrost soil carbon stocks following peak warming probably contributed to the rapid recovery from each event, while providing a sensitive carbon reservoir for the next hyperthermal. As background temperatures continued to rise following the PETM, the areal extent of permafrost steadily declined, resulting in an incrementally smaller available carbon pool and smaller hyperthermals at each successive orbital forcing maximum. A mechanism linking Earth's orbital properties with release of soil carbon from permafrost provides a unifying model accounting for the salient

  8. Linked Extreme Weather Events during Winter 2009-2010 and 2010-2011 in the Context of Northern Hemisphere Circulation Anomalies

    NASA Astrophysics Data System (ADS)

    Bosart, L. F.; Archambault, H. M.; Cordeira, J. M.

    2011-12-01

    /PNA phase transition was associated with an extreme weather event that brought severe and record-setting cold to parts of the U.S. and Mexico, a powerful snow and ice storm in the Central U.S., and a subsequent and spectacular warm-up east of the Rockies. The purpose of this presentation will be to present an overview of the structure and evolution of the large-scale NH circulation anomalies during the 2009-2010 and 2010-2011 winters. Emphasis will be placed on showing how individual synoptic-scale weather events (e.g., recurving and transitioning western Pacific tropical cyclones, diabatically driven upper-level outflow from organized deep convection associated with the Madden-Julian Oscillation, and western North Atlantic storminess) contributed to the formation of significant and persistent large-scale circulation anomalies and how these large-scale circulation anomalies in turn impacted the storm tracks, regional temperature and precipitation anomalies, and the associated extreme weather.

  9. More extreme swings of the South Pacific convergence zone due to greenhouse warming.

    PubMed

    Cai, Wenju; Lengaigne, Matthieu; Borlace, Simon; Collins, Matthew; Cowan, Tim; McPhaden, Michael J; Timmermann, Axel; Power, Scott; Brown, Josephine; Menkes, Christophe; Ngari, Arona; Vincent, Emmanuel M; Widlansky, Matthew J

    2012-08-16

    The South Pacific convergence zone (SPCZ) is the Southern Hemisphere's most expansive and persistent rain band, extending from the equatorial western Pacific Ocean southeastward towards French Polynesia. Owing to its strong rainfall gradient, a small displacement in the position of the SPCZ causes drastic changes to hydroclimatic conditions and the frequency of extreme weather events--such as droughts, floods and tropical cyclones--experienced by vulnerable island countries in the region. The SPCZ position varies from its climatological mean location with the El Niño/Southern Oscillation (ENSO), moving a few degrees northward during moderate El Niño events and southward during La Niña events. During strong El Niño events, however, the SPCZ undergoes an extreme swing--by up to ten degrees of latitude toward the Equator--and collapses to a more zonally oriented structure with commensurately severe weather impacts. Understanding changes in the characteristics of the SPCZ in a changing climate is therefore of broad scientific and socioeconomic interest. Here we present climate modelling evidence for a near doubling in the occurrences of zonal SPCZ events between the periods 1891-1990 and 1991-2090 in response to greenhouse warming, even in the absence of a consensus on how ENSO will change. We estimate the increase in zonal SPCZ events from an aggregation of the climate models in the Coupled Model Intercomparison Project phases 3 and 5 (CMIP3 and CMIP5) multi-model database that are able to simulate such events. The change is caused by a projected enhanced equatorial warming in the Pacific and may lead to more frequent occurrences of extreme events across the Pacific island nations most affected by zonal SPCZ events.

  10. Winter warming as an important co-driver for Betula nana growth in western Greenland during the past century.

    PubMed

    Hollesen, Jørgen; Buchwal, Agata; Rachlewicz, Grzegorz; Hansen, Birger U; Hansen, Marc O; Stecher, Ole; Elberling, Bo

    2015-06-01

    Growing season conditions are widely recognized as the main driver for tundra shrub radial growth, but the effects of winter warming and snow remain an open question. Here, we present a more than 100 years long Betula nana ring-width chronology from Disko Island in western Greenland that demonstrates a highly significant and positive growth response to both summer and winter air temperatures during the past century. The importance of winter temperatures for Betula nana growth is especially pronounced during the periods from 1910-1930 to 1990-2011 that were dominated by significant winter warming. To explain the strong winter importance on growth, we assessed the importance of different environmental factors using site-specific measurements from 1991 to 2011 of soil temperatures, sea ice coverage, precipitation and snow depths. The results show a strong positive growth response to the amount of thawing and growing degree-days as well as to winter and spring soil temperatures. In addition to these direct effects, a strong negative growth response to sea ice extent was identified, indicating a possible link between local sea ice conditions, local climate variations and Betula nana growth rates. Data also reveal a clear shift within the last 20 years from a period with thick snow depths (1991-1996) and a positive effect on Betula nana radial growth, to a period (1997-2011) with generally very shallow snow depths and no significant growth response towards snow. During this period, winter and spring soil temperatures have increased significantly suggesting that the most recent increase in Betula nana radial growth is primarily triggered by warmer winter and spring air temperatures causing earlier snowmelt that allows the soils to drain and warm quicker. The presented results may help to explain the recently observed 'greening of the Arctic' which may further accelerate in future years due to both direct and indirect effects of winter warming.

  11. Winter warming as an important co-driver for Betula nana growth in western Greenland during the past century.

    PubMed

    Hollesen, Jørgen; Buchwal, Agata; Rachlewicz, Grzegorz; Hansen, Birger U; Hansen, Marc O; Stecher, Ole; Elberling, Bo

    2015-06-01

    Growing season conditions are widely recognized as the main driver for tundra shrub radial growth, but the effects of winter warming and snow remain an open question. Here, we present a more than 100 years long Betula nana ring-width chronology from Disko Island in western Greenland that demonstrates a highly significant and positive growth response to both summer and winter air temperatures during the past century. The importance of winter temperatures for Betula nana growth is especially pronounced during the periods from 1910-1930 to 1990-2011 that were dominated by significant winter warming. To explain the strong winter importance on growth, we assessed the importance of different environmental factors using site-specific measurements from 1991 to 2011 of soil temperatures, sea ice coverage, precipitation and snow depths. The results show a strong positive growth response to the amount of thawing and growing degree-days as well as to winter and spring soil temperatures. In addition to these direct effects, a strong negative growth response to sea ice extent was identified, indicating a possible link between local sea ice conditions, local climate variations and Betula nana growth rates. Data also reveal a clear shift within the last 20 years from a period with thick snow depths (1991-1996) and a positive effect on Betula nana radial growth, to a period (1997-2011) with generally very shallow snow depths and no significant growth response towards snow. During this period, winter and spring soil temperatures have increased significantly suggesting that the most recent increase in Betula nana radial growth is primarily triggered by warmer winter and spring air temperatures causing earlier snowmelt that allows the soils to drain and warm quicker. The presented results may help to explain the recently observed 'greening of the Arctic' which may further accelerate in future years due to both direct and indirect effects of winter warming. PMID:25788025

  12. Global-warming-induced Increases in Extreme Precipitation are Smallest over Mountains

    NASA Astrophysics Data System (ADS)

    Shi, X.; Durran, D. R.

    2015-12-01

    Climate-model simulations predict an intensification of extreme precipitation in almost all areas of the world under global warming. Geographical variations in the magnitude of this intensification are clearly evident in the simulations, but most previous efforts to understand the factors responsible for the changes in extreme precipitation have focused on zonal averages, neglecting the variations that occur in different regions at the same latitude. Here we present climate-model simulations for an ocean-covered earth having simple idealized continents with north-south mountain barriers in its northern midlatitudes. We show that the sensitivity of extreme precipitation to increases in the global mean surface temperature is 3 %/K lower over the mountains than over the oceans and the plains. Fundamental factors responsible for changes in precipitation intensity may be divided between thermodynamic effects, arising through changes in temperature and moisture, and dynamical effects, produced by changes in the ascent rates of saturated air parcels. The difference in sensitivity among these regions is not due to thermodynamic effects, but rather to differences between the gravity-wave dynamics governing vertical velocities over the mountains and the cyclone dynamics governing vertical motions over the oceans and plains.

  13. Impacts of extraordinary warm and cold late-winter temperatures on observed and modelled plant phenology in Switzerland

    NASA Astrophysics Data System (ADS)

    Rutishauser, This; Stöckli, Reto

    2010-05-01

    The impact of gradual change in the climate system during the second half of the 20th century left a strong imprint on the timing of seasonal events in biotic and biotic systems such as e.g. plant development stages and the greenness of the Earth's surface. Temporal trends in seasonal events largely correspond to the effects expected from the increases in temperature. The impact of extraordinary temperature and precipitation events on plant phenology in spring is less understood. For example a strong early-spring frost event in the USA in April 2007 lead to reduced greenness and freeze damage to leaves and fruits of natural and horticultural species whereas a winter warming event in northern Scandinavia in December 2007 caused considerable damage to sub-Arctic dwarf shrub vegetation and reduced vegetation activity (26% reduced maximum Normalized Difference Vegetation Index NDVI relative to the previous year) in the following summer. In Germany and Switzerland, the effects of the extraordinary warm temperature anomalies of autumn 2006, winter 2006/2007 and spring 2007 showed strong impacts on selected plant phenological phases back to 1951 and 1702. Common hazel and snowdrop flowered up to 35 days earlier in Germany and beech and fruits tree were two weeks earlier in Switzerland. This contribution presents empirical evidence of extraordinary warm and cold late-winter temperatures on species-specific plant phenology and modelled landscape-scale phenology in Switzerland in the period 1958-2008. Species-specific observations were extracted from the Swiss Plant Phenological Network of MeteoSwiss for 23 low-altitude stations and 12 stations that report to the Global Climate Observation System (GCOS). Observations cover all climate regions and altitudes. For each GCOS station we also estimated daily Leaf Area Index with a prognostic phenology model. The model's empirical parameter space was constrained by assimilated Fraction of Photosynthetically Active Radiation

  14. Temperature inverted haloclines provide winter warm-water refugia for manatees in southwest Florida

    USGS Publications Warehouse

    Stith, Bradley M.; Reid, James P.; Langtimm, Catherine A.; Swain, Eric D.; Doyle, Terry J.; Slone, Daniel H.; Decker, Jeremy D.; Soderqvist, Lars E.

    2010-01-01

    Florida manatees (Trichechus manatus latirostris) overwintering in the Ten Thousand Islands and western Everglades have no access to power plants or major artesian springs that provide warm-water refugia in other parts of Florida. Instead, hundreds of manatees aggregate at artificial canals, basins, and natural deep water sites that act as passive thermal refugia (PTR). Monitoring at two canal sites revealed temperature inverted haloclines, which provided warm salty bottom layers that generally remained above temperatures considered adverse for manatees. At the largest PTR, the warmer bottom layer disappeared unless significant salt stratification was maintained by upstream freshwater inflow over a persistent tidal wedge. A detailed three-dimensional hydrology model showed that salinity stratification inhibited vertical convection induced by atmospheric cooling. Management or creation of temperature inverted haloclines may be a feasible and desirable option for resource managers to provide passive thermal refugia for manatees and other temperature sensitive aquatic species.

  15. Design of an Extreme Ultraviolet Spectrometer Suite for Isochoric-Heated Warm-Dense-Matter Studies

    NASA Astrophysics Data System (ADS)

    Ivancic, S.; Stillman, C. R.; Nilson, P. M.; Froula, D. H.

    2015-11-01

    An ultrafast streaked extreme ultraviolet (XUV) spectrometer (5 to 35 nm) is in development for the measurement of warm dense matter (WDM). In contrast to other forms of pyrometry where the temperature is inferred from bulk x-ray emission, XUV emission is restricted to the sample surface, allowing for the measurement of temperature at the material-vacuum interface. The measurement of the surface temperature is of particular importance in constraining models for the release of WDM. The divergence of surface and bulk temperature measurements may indicate gradients in temperature in the target. Coupling the XUV spectrometer to an ultrafast streak camera allows for the observation of picosecond time-scale evolution of the surface layer temperature. Two high-throughput XUV spectrometers are being designed to measure the time-resolved and absolute XUV emission. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  16. Extreme monsoon precipitation events over South Asia in a warming world

    NASA Astrophysics Data System (ADS)

    Raghavan, K.; Sabin, T. P.; Mujumdar, M.; Priya, P.

    2012-04-01

    The recent series of flood events over Pakistan and Northwest India during the monsoon seasons of 2010 and 2011 are examples of extreme phenomena during the last century that have evoked considerable interest among various scientific communities. One of the causes for the 2010 intense precipitation over Pakistan has been attributed to the interaction between the tropical monsoon surge and southward intruding extra-tropical circulation anomalies (Hong et al. 2011). On the other hand, it has been hypothesized by Mujumdar et al. (2012) that the westward shift of the West Pacific Subtropical High (WPSH) in response to the strong La Nina conditions during 2010 was instrumental in altering the convection and circulation over the Bay of Bengal and the monsoon trough region, which in turn sustained the moist convective activities over Indo-Pak through transport of moisture from the Arabian Sea. However several aspects of the dynamics of these intense monsoon precipitation events are not adequately understood especially when atmospheric convective instabilities are expected to amplify in the backdrop of the ongoing global warming. Here, we have carried out a set of ensemble simulation experiments using a high-resolution global climate model to understand the evolution of intense monsoon precipitation events over Pakistan and Northwest India as in 2010. The results based on the model simulations indicate that while interactions among the WPSH, the South Asian monsoon trough and sub-tropical westerlies are conducive for development of convective instabilities over the Indo-Pak region, the local convective activities are found to significantly amplify in response to the large build up of moisture associated with global warming. The present results have implications in understanding how extreme monsoon precipitation events in the Indo-Pak region might have responded to past climatic variations.

  17. Establishing a missing link: warm summers and winter snow cover promote shrub expansion into alpine tundra in Scandinavia.

    PubMed

    Hallinger, Martin; Manthey, Michael; Wilmking, Martin

    2010-06-01

    *Shrub expansion in alpine and arctic areas is a process with possibly profound implications for ecosystem functioning. The recent shrub expansion has been mainly documented by remote sensing techniques, but the drivers for this process largely remain hypotheses. *Here, we outline a dendrochronological method, adapted to shrubs, to address these hypotheses and then present a mechanism for the current shrub expansion by linking recent climate change to shrub growth performance in northern Sweden. *A pronounced increase in radial and vertical growth during recent decades along an elevational gradient from treeline to shrubline indicates an ongoing shrub expansion. Age distribution of the shrub population indicates the new colonization of shrubs at high elevations. *Shrub growth is correlated with warm summers and winter snow cover and suggests the potential for large-scale ecosystem changes if climate change continues as projected.

  18. Wintering birds avoid warm sunshine: predation and the costs of foraging in sunlight.

    PubMed

    Carr, Jennie M; Lima, Steven L

    2014-03-01

    Wintering birds can gain significant thermal benefits by foraging in direct sunlight. However, exposure to bright sunlight might make birds easier to detect by predators and may also cause visual glare that can reduce a bird's ability to monitor the environment. Thus, birds likely experience a trade-off between the thermal benefits and predation-related costs of foraging in direct sunlight. To examine this possible thermoregulation-predation trade-off, we monitored the behavior of mixed-species flocks of wintering emberizid sparrows foraging in alternating strips of sunlight and shade. On average, these sparrows routinely preferred to forage in the shade, despite midday air temperatures as much as 30 °C below their thermoneutral zone. This preference for shade was strongest at relatively high temperatures when the thermal benefits of foraging in sunlight were reduced, suggesting a thermoregulation-predation trade-off. Glare could be reduced if birds faced away from the sun while feeding in direct sunlight, but we found that foraging birds tended to face southward (the direction of the sun). We speculate that other factors, such as the likely direction of predator approach, may explain this southerly orientation, particularly if predators use solar glare to their advantage during an attack. This interpretation is supported by the fact that birds had the weakest southerly orientation on cloudy days. Wintering birds may generally avoid foraging in direct sunlight to minimize their risk of predation. However, given the thermal benefits of sunshine, such birds may benefit from foraging in habitats that provide a mosaic of sunlit and shaded microhabitats.

  19. More-frequent extreme northward shifts of eastern Indian Ocean tropical convergence under greenhouse warming.

    PubMed

    Weller, Evan; Cai, Wenju; Min, Seung-Ki; Wu, Lixin; Ashok, Karumuri; Yamagata, Toshio

    2014-08-15

    The Intertropical Convergence Zone (ITCZ) in the tropical eastern Indian Ocean exhibits strong interannual variability, often co-occurring with positive Indian Ocean Dipole (pIOD) events. During what we identify as an extreme ITCZ event, a drastic northward shift of atmospheric convection coincides with an anomalously strong north-minus-south sea surface temperature (SST) gradient over the eastern equatorial Indian Ocean. Such shifts lead to severe droughts over the maritime continent and surrounding islands but also devastating floods in southern parts of the Indian subcontinent. Understanding future changes of the ITCZ is therefore of major scientific and socioeconomic interest. Here we find a more-than-doubling in the frequency of extreme ITCZ events under greenhouse warming, estimated from climate models participating in the Coupled Model Intercomparison Project phase 5 that are able to simulate such events. The increase is due to a mean state change with an enhanced north-minus-south SST gradient and a weakened Walker Circulation, facilitating smaller perturbations to shift the ITCZ northwards.

  20. Understanding factors influencing vulnerable older people keeping warm and well in winter: a qualitative study using social marketing techniques

    PubMed Central

    Lusambili, Adelaide; Homer, Catherine; Abbott, Joanne; Cooke, Joanne Mary; Stocks, Amanda Jayne; McDaid, Kathleen Anne

    2012-01-01

    Objectives To understand the influences and decisions of vulnerable older people in relation to keeping warm in winter. Design A qualitative study incorporating in-depth, semi-structured individual and group interviews, framework analysis and social marketing segmentation techniques. Setting Rotherham, South Yorkshire, UK. Participants 50 older people (>55) and 25 health and social care staff underwent individual interview. The older people also had household temperature measurements. 24 older people and 19 health and social care staff participated in one of the six group interviews. Results Multiple complex factors emerged to explain whether vulnerable older people were able to keep warm. These influences combined in various ways that meant older people were not able to or preferred not to access help or change home heating behaviour. Factors influencing behaviours and decisions relating to use of heating, spending money, accessing cheaper tariffs, accessing benefits or asking for help fell into three main categories. These were situational and contextual factors, attitudes and values, and barriers. Barriers included poor knowledge and awareness, technology, disjointed systems and the invisibility of fuel and fuel payment. Findings formed the basis of a social marketing segmentation model used to develop six pen portraits that illustrated how factors that conspire against older people being able to keep warm. Conclusions The findings illustrate how and why vulnerable older people may be at risk of a cold home. The pen portraits provide an accessible vehicle and reflective tool to raise the capacity of the NHS in responding to their needs in line with the Cold Weather Plan. PMID:22798252

  1. Can a nudge keep you warm? Using nudges to reduce excess winter deaths: insight from the Keeping Warm in Later Life Project (KWILLT)

    PubMed Central

    Allmark, Peter; Tod, Angela M.

    2014-01-01

    Nudges are interventions that aim to change people's behaviour through changing the environment in which they choose rather than appealing to their reasoning. Nudges have been proposed as of possible use in relation to health-related behaviour. However, nudges have been criticized as ethically dubious because they bypass peoples reasoning and (anyway) are of little help in relation to affecting ill-health that results from social determinants, such as poverty. Reducing the rate of excess winter deaths (EWDs) is a public health priority; however, EWD seems clearly to be socially determined such that nudges arguably have little role. This article defends two claims: (i) nudges could have a place in tackling even the heavily socially determined problem of EWD. We draw on evidence from an empirical study, the Keeping Warm in Later Life Project (KWILLT), to argue that in some cases the risk of cold is within the person’s control to some extent such that environmental modifications to influence behaviour such as nudges are possible. (ii) Some uses of behavioural insights in the form of nudges are acceptable, including some in the area of EWD. We suggest a question-based framework by which to judge the ethical acceptability of nudges. PMID:23873728

  2. Can a nudge keep you warm? Using nudges to reduce excess winter deaths: insight from the Keeping Warm in Later Life Project (KWILLT).

    PubMed

    Allmark, Peter; Tod, Angela M

    2014-03-01

    Nudges are interventions that aim to change people's behaviour through changing the environment in which they choose rather than appealing to their reasoning. Nudges have been proposed as of possible use in relation to health-related behaviour. However, nudges have been criticized as ethically dubious because they bypass peoples reasoning and (anyway) are of little help in relation to affecting ill-health that results from social determinants, such as poverty. Reducing the rate of excess winter deaths (EWDs) is a public health priority; however, EWD seems clearly to be socially determined such that nudges arguably have little role. This article defends two claims: (i) nudges could have a place in tackling even the heavily socially determined problem of EWD. We draw on evidence from an empirical study, the Keeping Warm in Later Life Project (KWILLT), to argue that in some cases the risk of cold is within the person's control to some extent such that environmental modifications to influence behaviour such as nudges are possible. (ii) Some uses of behavioural insights in the form of nudges are acceptable, including some in the area of EWD. We suggest a question-based framework by which to judge the ethical acceptability of nudges. PMID:23873728

  3. Communicating Climate Uncertainties: Challenges and Opportunities Related to Spatial Scales, Extreme Events, and the Warming 'Hiatus'

    NASA Astrophysics Data System (ADS)

    Casola, J. H.; Huber, D.

    2013-12-01

    Many media, academic, government, and advocacy organizations have achieved sophistication in developing effective messages based on scientific information, and can quickly translate salient aspects of emerging climate research and evolving observations. However, there are several ways in which valid messages can be misconstrued by decision makers, leading them to inaccurate conclusions about the risks associated with climate impacts. Three cases will be discussed: 1) Issues of spatial scale in interpreting climate observations: Local climate observations may contradict summary statements about the effects of climate change on larger regional or global spatial scales. Effectively addressing these differences often requires communicators to understand local and regional climate drivers, and the distinction between a 'signal' associated with climate change and local climate 'noise.' Hydrological statistics in Missouri and California are shown to illustrate this case. 2) Issues of complexity related to extreme events: Climate change is typically invoked following a wide range of damaging meteorological events (e.g., heat waves, landfalling hurricanes, tornadoes), regardless of the strength of the relationship between anthropogenic climate change and the frequency or severity of that type of event. Examples are drawn from media coverage of several recent events, contrasting useful and potentially confusing word choices and frames. 3) Issues revolving around climate sensitivity: The so-called 'pause' or 'hiatus' in global warming has reverberated strongly through political and business discussions of climate change. Addressing the recent slowdown in warming yields an important opportunity to raise climate literacy in these communities. Attempts to use recent observations as a wedge between climate 'believers' and 'deniers' is likely to be counterproductive. Examples are drawn from Congressional testimony and media stories. All three cases illustrate ways that decision

  4. Changes in extreme temperature and precipitation events in the Loess Plateau (China) during 1960-2013 under global warming

    NASA Astrophysics Data System (ADS)

    Sun, Wenyi; Mu, Xingmin; Song, Xiaoyan; Wu, Dan; Cheng, Aifang; Qiu, Bing

    2016-02-01

    In recent decades, extreme climatic events have been a major issue worldwide. Regional assessments on various climates and geographic regions are needed for understanding uncertainties in extreme events' responses to global warming. The objective of this study was to assess the annual and decadal trends in 12 extreme temperature and 10 extreme precipitation indices in terms of intensity, frequency, and duration over the Loess Plateau during 1960-2013. The results indicated that the regionally averaged trends in temperature extremes were consistent with global warming. The occurrence of warm extremes, including summer days (SU), tropical nights (TR), warm days (TX90), and nights (TN90) and a warm spell duration indicator (WSDI), increased by 2.76 (P < 0.01), 1.24 (P < 0.01), 2.60 (P = 0.0003), 3.41 (P < 0.01), and 0.68 (P = 0.0041) days/decade during the period of 1960-2013, particularly, sharp increases in these indices occurred in 1985-2000. Over the same period, the occurrence of cold extremes, including frost days (FD), ice days (ID), cold days (TX10) and nights (TN10), and a cold spell duration indicator (CSDI) exhibited decreases of - 3.22 (P < 0.01), - 2.21 (P = 0.0028), - 2.71 (P = 0.0028), - 4.31 (P < 0.01), and - 0.69 (P = 0.0951) days/decade, respectively. Moreover, extreme warm events in most regions tended to increase while cold indices tended to decrease in the Loess Plateau, but the trend magnitudes of cold extremes were greater than those of warm extremes. The growing season (GSL) in the Loess Plateau was lengthened at a rate of 3.16 days/decade (P < 0.01). Diurnal temperature range (DTR) declined at a rate of - 0.06 °C /decade (P = 0.0931). Regarding the precipitation indices, the annual total precipitation (PRCPTOT) showed no obvious trends (P = 0.7828). The regionally averaged daily rainfall intensity (SDII) exhibited significant decreases (- 0.14 mm/day/decade, P = 0.0158), whereas consecutive dry days (CDD) significantly increased (1.96 days

  5. Moving in extreme environments: open water swimming in cold and warm water.

    PubMed

    Tipton, Michael; Bradford, Carl

    2014-01-01

    Open water swimming (OWS), either 'wild' such as river swimming or competitive, is a fast growing pastime as well as a part of events such as triathlons. Little evidence is available on which to base high and low water temperature limits. Also, due to factors such as acclimatisation, which disassociates thermal sensation and comfort from thermal state, individuals cannot be left to monitor their own physical condition during swims. Deaths have occurred during OWS; these have been due to not only thermal responses but also cardiac problems. This paper, which is part of a series on 'Moving in Extreme Environments', briefly reviews current understanding in pertinent topics associated with OWS. Guidelines are presented for the organisation of open water events to minimise risk, and it is concluded that more information on the responses to immersion in cold and warm water, the causes of the individual variation in these responses and the precursors to the cardiac events that appear to be the primary cause of death in OWS events will help make this enjoyable sport even safer.

  6. Moving in extreme environments: open water swimming in cold and warm water

    PubMed Central

    2014-01-01

    Open water swimming (OWS), either ‘wild’ such as river swimming or competitive, is a fast growing pastime as well as a part of events such as triathlons. Little evidence is available on which to base high and low water temperature limits. Also, due to factors such as acclimatisation, which disassociates thermal sensation and comfort from thermal state, individuals cannot be left to monitor their own physical condition during swims. Deaths have occurred during OWS; these have been due to not only thermal responses but also cardiac problems. This paper, which is part of a series on ‘Moving in Extreme Environments’, briefly reviews current understanding in pertinent topics associated with OWS. Guidelines are presented for the organisation of open water events to minimise risk, and it is concluded that more information on the responses to immersion in cold and warm water, the causes of the individual variation in these responses and the precursors to the cardiac events that appear to be the primary cause of death in OWS events will help make this enjoyable sport even safer. PMID:24921042

  7. Variability in projected elevation dependent warming in boreal midlatitude winter in CMIP5 climate models and its potential drivers

    NASA Astrophysics Data System (ADS)

    Rangwala, Imtiaz; Sinsky, Eric; Miller, James R.

    2016-04-01

    The future rate of climate change in mountains has many potential human impacts, including those related to water resources, ecosystem services, and recreation. Analysis of the ensemble mean response of CMIP5 global climate models (GCMs) shows amplified warming in high elevation regions during the cold season in boreal midlatitudes. We examine how the twenty-first century elevation-dependent response in the daily minimum surface air temperature [d(ΔTmin)/dz] varies among 27 different GCMs during winter for the RCP 8.5 emissions scenario. The focus is on regions within the northern hemisphere mid-latitude band between 27.5°N and 40°N, which includes both the Rocky Mountains and the Tibetan Plateau/Himalayas. We find significant variability in d(ΔTmin)/dz among the individual models ranging from 0.16 °C/km (10th percentile) to 0.97 °C/km (90th percentile), although nearly all of the GCMs (24 out of 27) show a significant positive value for d(ΔTmin)/dz. To identify some of the important drivers associated with the variability in d(ΔTmin)/dz during winter, we evaluate the co-variance between d(ΔTmin)/dz and the differential response of elevation-based anomalies in different climate variables as well as the GCMs' spatial resolution, their global climate sensitivity, and their elevation-dependent free air temperature response. We find that d(ΔTmin)/dz has the strongest correlation with elevation-dependent increases in surface water vapor, followed by elevation-dependent decreases in surface albedo, and a weak positive correlation with the GCMs' free air temperature response.

  8. Effects of warm winter temperature on the abundance and gonotrophic activity of Culex (Diptera: Culicidae) in California.

    PubMed

    Reisen, William K; Thiemann, Tara; Barker, Christopher M; Lu, Helen; Carroll, Brian; Fang, Ying; Lothrop, Hugh D

    2010-03-01

    Culex tarsalis Coquillett, Cx. quinquefasciatus Say, and Cx. pipiens L. were collected during the warm winter of 2009 using dry ice-baited and gravid traps and walk-in red boxes positioned in desert, urban, and agricultural habitats in Riverside, Los Angeles, Kern, and Yolo Counties. Temperatures exceeded the preceding 50 yr averages in all locations for most of January, whereas rainfall was absent or below average. Abundance of Culex species in traps during January ranged from 83 to 671% of the prior 5 yr average in all locations. Few females collected resting were in diapause during January based on follicular measurements. Evidence for early season gonotrophic activity included the detection of freshly bloodfed, gravid, and parous females in resting collections, gravid oviposition site-seeking females in gravid female traps, and nulliparous and parous host-seeking females at dry ice-baited traps. Female Culex seemed to employ multiple overwintering strategies in California, including larval and adult quiescence, adult female diapause, and an intermediate situation with adult females collected with enlarged follicles, but without evident vitellogenesis. West Nile, St. Louis, or western equine encephalitis viruses were not detected in 198 pools of adults or 56 pools of adults reared from field-collected immatures collected during January and February 2009. Our preliminary data may provide insight into how climate change may extend the mosquito season in California. PMID:20380305

  9. The impact of ENSO and the NAO on extreme winter precipitation in North America in observations and regional climate models

    NASA Astrophysics Data System (ADS)

    Whan, Kirien; Zwiers, Francis

    2016-05-01

    The relationship between winter precipitation in North America and indices of the North Atlantic Oscillation (NAO) and El Niño-Southern Oscillation (ENSO) is evaluated using non-stationary generalized extreme value distributions with the indices as covariates. Both covariates have a statistically significant influence on precipitation that is well simulated by two regional climate models (RCMs), CanRCM4 and CRCM5. The observed influence of the NAO on extreme precipitation is largest in eastern North America, with the likelihood of a negative phase extreme rainfall event decreased in the north and increased in the south under the positive phase of the NAO. This pattern is generally well simulated by the RCMs although there are some differences in the extent of influence, particularly south of the Great Lakes. A La Niña-magnitude extreme event is more likely to occur under El Niño conditions in California and the southern United States, and less likely in most of Canada and a region south of the Great Lakes. This broad pattern is also simulated well by the RCMs but they do not capture the increased likelihood in California. In some places the extreme precipitation response in the RCMs to external forcing from a covariate is of the opposite sign, despite use of the same lateral boundary conditions and dynamical core. This demonstrates the importance of model physics for teleconnections to extreme precipitation.

  10. Bacterial responses to fluctuations and extremes in temperature and brine salinity at the surface of Arctic winter sea ice.

    PubMed

    Ewert, Marcela; Deming, Jody W

    2014-08-01

    Wintertime measurements near Barrow, Alaska, showed that bacteria near the surface of first-year sea ice and in overlying saline snow experience more extreme temperatures and salinities, and wider fluctuations in both parameters, than bacteria deeper in the ice. To examine impacts of such conditions on bacterial survival, two Arctic isolates with different environmental tolerances were subjected to winter-freezing conditions, with and without the presence of organic solutes involved in osmoprotection: proline, choline, or glycine betaine. Obligate psychrophile Colwellia psychrerythraea strain 34H suffered cell losses under all treatments, with maximal loss after 15-day exposure to temperatures fluctuating between -7 and -25 °C. Osmoprotectants significantly reduced the losses, implying that salinity rather than temperature extremes presents the greater stress for this organism. In contrast, psychrotolerant Psychrobacter sp. strain 7E underwent miniaturization and fragmentation under both fluctuating and stable-freezing conditions, with cell numbers increasing in most cases, implying a different survival strategy that may include enhanced dispersal. Thus, the composition and abundance of the bacterial community that survives in winter sea ice may depend on the extent to which overlying snow buffers against extreme temperature and salinity conditions and on the availability of solutes that mitigate osmotic shock, especially during melting.

  11. Global and Regional Variations in Mean Temperature and Warm Extremes in Large-Member Historical AGCM Simulation

    NASA Astrophysics Data System (ADS)

    Kamae, Y.; Shiogama, H.; Imada, Y.; Mori, M.; Arakawa, O.; Mizuta, R.; Yoshida, K.; Ishii, M.; Watanabe, M.; Kimoto, M.; Ueda, H.

    2015-12-01

    Frequency of heat extremes during the summer season has increased continuously since the late 20th century despite the global warming hiatus. In previous studies, anthropogenic influences, natural variation in sea surface temperature (SST), and internal atmospheric variabilities are suggested to be factors contributing to the increase in the frequency of warm extremes. Here 100-member ensemble historical simulations were performed (called "database for Probabilistic Description of Future climate"; d4PDF) to examine physical mechanisms responsible for the increasing hot summers and attribute to the anthropogenic influences or natural climate variability. 60km resolution MRI-AGCM ensemble simulations can reproduce historical variations in the mean temperature and warm extremes. Natural SST variability in the Pacific and Atlantic Oceans contribute to the decadal variation in the frequency of hot summers in the Northern Hemisphere middle latitude. For example, the surface temperature over western North America, including California, is largely influenced by anomalous atmospheric circulation pattern associated with Pacific SST variability. Future projections based on anomalous SST patterns derived from coupled climate model simulations will also be introduced.

  12. Future Variations of Wave Climate in Winter Japan: Application of Pseudo Global Warming Dynamic Downscaling Method for CMIP5 output and a Wave Model Simulation

    NASA Astrophysics Data System (ADS)

    Taniguchi, K.

    2014-12-01

    Ocean waves change alongshore topographies and their effects reach to ecological systems and coastal infrastructures. Ocean waves are mainly formed by sea surface wind, then variations in sea surface winds can cause changes in ocean waves. Under the condition of global warming, atmospheric motion will change in future climate and they will give changes in wave climates. However, effects of global warming on wave climate have not yet investigated in detail. In this study, a dynamic downscaling method by a weather prediction model (WRF developed by NCAR) is applied to obtain detail information of sea surface wind in the present and future climates. The ocean wave is simulated by a wave model (WaveWatch-III developed by NOAA) with the downscaled wind in the present and future climate, then variations in wave climate in future are investigated. For future climate, climate projections in Coupled Model Intercomparison Project phase 5 (CMIP5) are used. For future scenario, the representative concentrate pathways 4.5 (RCP4.5) is selected. Variations of ocean waves in the Sea of Japan is focused in this work. Over the Sea of Japan, the strong northwesterly blows from the Eurasian Continent to the Japan islands in winter and causes high waves, and sometimes it causes marine accidents and breaks in coastal civil structures. The results of WaveWatch-III showed that the maximum value of significant wave height becomes smaller in the northern and central part of the Sea of Japan, however, clear increases are found in the southern part in future. In some regions, the maximum wave heights in future become 4 meter larger than in present. On the other hand, there are variations in frequency distribution of significant wave height. The frequency of modestly high waves increases and the low wave frequency decreases mainly in January and February (even in areas with smaller maximum significant wave height in future). Without extremely high ocean waves, variations in frequency

  13. Variations of Kelvin waves around the TTL region during the stratospheric sudden warming events in the Northern Hemisphere winter

    NASA Astrophysics Data System (ADS)

    Jia, Yue; Zhang, Shao Dong; Yi, Fan; Huang, Chun Ming; Huang, Kai Ming; Gong, Yun; Gan, Quan

    2016-03-01

    Spatial and temporal variabilities of Kelvin waves during stratospheric sudden warming (SSW) events are investigated by the ERA-Interim reanalysis data, and the results are validated by the COSMIC temperature data. A case study on an exceptionally large SSW event in 2009, and a composite analysis comprising 18 events from 1980 to 2013 are presented. During SSW events, the average temperature increases by 20 K in the polar stratosphere, while the temperature in the tropical stratosphere decreases by about 4 K. Kelvin wave with wave numbers 1 and 2, and periods 10-20 days, clearly appear around the tropical tropopause layer (TTL) during SSWs. The Kelvin wave activity shows obvious coupling with the convection localized in the India Ocean and western Pacific (Indo-Pacific) region. Detailed analysis suggests that the enhanced meridional circulation driven by the extratropical planetary wave forcing during SSW events leads to tropical upwelling, which further produces temperature decrease in the tropical stratosphere. The tropical upwelling and cooling consequently result in enhancement of convection in the equatorial region, which excites the strong Kelvin wave activity. In addition, we investigated the Kelvin wave acceleration to the eastward zonal wind anomalies in the equatorial stratosphere during SSW events. The composite analysis shows that the proportion of Kelvin wave contribution ranges from 5 to 35 % during SSWs, much larger than in the non-SSW mid-winters (less than 5 % in the stratosphere). However, the Kelvin wave alone is insufficient to drive the equatorial eastward zonal wind anomalies during the SSW events, which suggests that the effects of other types of equatorial waves may not be neglected.

  14. Detecting Climate Signals in Precipitation Extremes from TRMM (1998-2013) - Increasing Contrast Between Wet and Dry Extremes During the "Global Warming Hiatus"

    NASA Technical Reports Server (NTRS)

    Wu, Huey-Tzu Jenny; Lau, William K.-M.

    2016-01-01

    We investigate changes in daily precipitation extremes using Tropical Rainfall Measuring Mission (TRMM) data (1998-2013), which coincides with the "global warming hiatus." Results show a change in probability distribution functions of local precipitation events (LPEs) during this period consistent with previous global warming studies, indicating increasing contrast between wet and dry extremes, with more intense LPE, less moderate LPE, and more dry (no rain) days globally. Analyses for land and ocean separately reveal more complex and nuanced changes over land, characterized by a strong positive trend (+12.0% per decade, 99% confidence level (c.l.)) in frequency of extreme LPEs over the Northern Hemisphere extratropics during the wet season but a negative global trend (-6.6% per decade, 95% c.l.) during the dry season. A significant global drying trend (3.2% per decade, 99% c.l.) over land is also found during the dry season. Regions of pronounced increased dry events include western and central U.S., northeastern Asia, and Southern Europe/Mediterranean.

  15. Extreme Winter Cyclones in the North Atlantic in a Last Millennium Climate Simulation with CESM1.0.1

    NASA Astrophysics Data System (ADS)

    Blumer, Sandro R.; Raible, Christoph C.; Lehner, Flavio; Stocker, Thomas F.

    2016-04-01

    Extreme cyclones and their associated impacts are a major threat to mankind, as they often result in heavy precipitation events and severe winds. The last millennium is closest to the Anthropocene and has the best coverage of paleo-climatic information. Therefore, it can serve as a test bed for estimating natural forcing variations beyond the recent observational period and can deliver insight into the frequency and intensity of extreme events, including strong cyclones and their dependency on internal variability and external forcing. The aim of this study is to investigate how the frequency and intensity of extreme cyclones in the North Atlantic have changed in the last millennium, and investigate phases which deviate more than one standard deviation. In particular the changes during prolonged cold and warm periods and the 21st century are analysed to assess the external forcing imprint. We use a comprehensive fully-coupled transient climate simulation of the last millennium (AD 1000-2100) with a relatively high spatial (0.9x1.25 degrees) resolution. Cyclones are then detected and tracked in 12-hourly output using an algorithm that is based on the geopotential height field on 1000 hPa. In addition to the tracking, a Gaussian function is fitted to the depressions in the geopotential height field at every time step in order to have a geometric representation of the low pressure systems. Additionally, two intensity indices for extreme cyclones are defined: the 90 percentile of the mean gradient in geopotential and the 90 percentile of the precipitation within a radius of one standard deviation of the approximated Gaussian function around the cyclone. These criteria consider two aspects of cyclone's intensity: extremes in wind and precipitation. A 30-yr running window is applied to the entire simulation. Within each window the cyclone frequency and the indices for extreme wind and extreme precipitation cyclones are averaged. This analysis reveals decadal to

  16. Near cessation of Eighteen Degree Water renewal in the western North Atlantic in the warm winter of 2011-2012

    NASA Astrophysics Data System (ADS)

    Billheimer, Sam; Talley, Lynne D.

    2013-12-01

    The winter of 2011-2012 was a particularly weak season for the renewal of "Eighteen Degree Water" (EDW), the Subtropical Mode Water of the western North Atlantic, as demonstrated by Argo and repeat hydrography. Weak, late winter buoyancy forcing produced shallower than usual winter mixed layers throughout the subtropical gyre, failing to thoroughly ventilate the underlying mode water, and can likely be attributed to the coinciding high, positive phase of the North Atlantic Oscillation (NAO). The only region where EDW was renewed was in the far northeastern Sargasso Sea where it is understood that the Gulf Stream plays a central role in formation; no EDW formed over the large regions of the gyre where deep winter mixed layers driven by surface buoyancy loss normally create EDW. The present investigation evaluates 2011-2012 winter buoyancy content anomalies, surface buoyancy fluxes, and advection of buoyancy via the Gulf Stream and compares them with the previous seven winters that exhibited more vigorous EDW formation. The weak 2011-2012 formation did not result from increased Gulf Stream heat advection, and was also not driven by preconditioning as the buoyancy content of the region prior to the onset of winter forcing was not unusually high. Rather, the weak formation resulted from climatologically weak surface cooling late in winter. The winter of 2007-2008 also experienced particularly weak EDW formation under similar conditions, including a high NAO and weak late winter surface cooling.

  17. Is Shade Beneficial for Mediterranean Shrubs Experiencing Periods of Extreme Drought and Late-winter Frosts?

    PubMed Central

    Valladares, Fernando; Zaragoza-Castells, Joana; Sánchez-Gómez, David; Matesanz, Silvia; Alonso, Beatriz; Portsmuth, Angelika; Delgado, Antonio; Atkin, Owen K.

    2008-01-01

    Background and Aims Plants are naturally exposed to multiple, frequently interactive stress factors, most of which are becoming more severe due to global change. Established plants have been reported to facilitate the establishment of juvenile plants, but net effects of plant–plant interactions are difficult to assess due to complex interactions among environmental factors. An investigation was carried out in order to determine how two dominant evergreen shrubs (Quercus ilex and Arctostaphylos uva-ursi) co-occurring in continental, Mediterranean habitats respond to multiple abiotic stresses and whether the shaded understorey conditions ameliorate the negative effects of drought and winter frosts on the physiology of leaves. Methods Microclimate and ecophysiology of sun and shade plants were studied at a continental plateau in central Spain during 2004–2005, with 2005 being one of the driest and hottest years on record; several late-winter frosts also occurred in 2005. Key Results Daytime air temperature and vapour pressure deficit were lower in the shade than in the sun, but soil moisture was also lower in the shade during the spring and summer of 2005, and night-time temperatures were higher in the shade. Water potential, photochemical efficiency, light-saturated photosynthesis, stomatal conductance and leaf 13C composition differed between sun and shade individuals throughout the seasons, but differences were species specific. Shade was beneficial for leaf-level physiology in Q. ilex during winter, detrimental during spring for both species, and of little consequence in summer. Conclusions The results suggest that beneficial effects of shade can be eclipsed by reduced soil moisture during dry years, which are expected to be more frequent in the most likely climate change scenarios for the Mediterranean region. PMID:18819947

  18. Abrupt summer warming and changes in temperature extremes over Northeast Asia since the mid-1990s: Drivers and physical processes

    NASA Astrophysics Data System (ADS)

    Dong, Buwen; Sutton, Rowan T.; Chen, Wei; Liu, Xiaodong; Lu, Riyu; Sun, Ying

    2016-09-01

    This study investigated the drivers and physical processes for the abrupt decadal summer surface warming and increases in hot temperature extremes that occurred over Northeast Asia in the mid-1990s. Observations indicate an abrupt increase in summer mean surface air temperature (SAT) over Northeast Asia since the mid-1990s. Accompanying this abrupt surface warming, significant changes in some temperature extremes, characterized by increases in summer mean daily maximum temperature (Tmax), daily minimum temperature (Tmin), annual hottest day temperature (TXx), and annual warmest night temperature (TNx) were observed. There were also increases in the frequency of summer days (SU) and tropical nights (TR). Atmospheric general circulation model experiments forced by changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gas (GHG) concentrations, and anthropogenic aerosol (AA) forcing, relative to the period 1964-93, reproduced the general patterns of observed summer mean SAT changes and associated changes in temperature extremes, although the abrupt decrease in precipitation since the mid-1990s was not simulated. Additional model experiments with different forcings indicated that changes in SST/SIE explained 76% of the area-averaged summer mean surface warming signal over Northeast Asia, while the direct impact of changes in GHG and AA explained the remaining 24% of the surface warming signal. Analysis of physical processes indicated that the direct impact of the changes in AA (through aerosol-radiation and aerosol-cloud interactions), mainly related to the reduction of AA precursor emissions over Europe, played a dominant role in the increase in TXx and a similarly important role as SST/SIE changes in the increase in the frequency of SU over Northeast Asia via AA-induced coupled atmosphere-land surface and cloud feedbacks, rather than through a direct impact of AA changes on cloud condensation nuclei. The modelling results also imply

  19. Responses to Global Warming Over the Eastern and Central Tibetan Plateau as Reflected in Day-time and Night-time Temperatures, Extreme Temperature Events, and Growing Season Length During 1961-2003

    NASA Astrophysics Data System (ADS)

    Yin, Z.; Liu, X.; Shao, X.

    2006-12-01

    This study examines the trends and variation patterns in daily maximum (day-time) and minimum (night-time) temperatures (hereafter referred to as Tm and Tn), extreme events, and growing season lengths over the eastern and central Tibetan Plateau (TP), in comparison with the results from other regions. Data during the period 1961-2003 from 66 weather stations over the eastern and central TP with elevations above 2000 m are used in this study, after going through rigorous quality assessment/quality control procedures. Statistically significant warming trends are identified in various measures of the temperature regime, especially in night- time temperatures, extreme warm/cold events, and diurnal temperature range (DTR). We find that the trends in Tn and Tm display distinct spatial patterns in the study region. The warming trends in winter night-time temperatures are among the highest when compared with studies conducted in other regions. Our results also confirm the asymmetric pattern of greater warming trends in minimum or night-time temperatures as compared to the day-time temperatures, which reduces the DTR in the region. Based on the time-varying percentiles of Tn and Tm, prominent warming trends are found in Tn during cold season months across the relative temperature scale of both warm and cold events. The warming in night-time temperatures causes the number of frost days to decrease significantly and the number of warm days to increase. The mean length of growing season has increased by approximately 17 days during the 43-year study period for the region. Most of the record-setting months for cold events are found in the earlier part of the study period, while that of the warm events have occurred mostly in the later half, especially since the 1990s. The changes in the temperature regime in this region may have brought regional-specific impacts on the ecosystems. It is found that grain production in Qinghai Province, located in the northeastern part of the

  20. Improving Conservation of Florida Manatees ( Trichechus manatus latirostris): Conceptualization and Contributions Toward a Regional Warm-Water Network Management Strategy for Sustainable Winter Habitat

    NASA Astrophysics Data System (ADS)

    Flamm, Richard Owen; Reynolds, John Elliot; Harmak, Craig

    2013-01-01

    We used southwestern Florida as a case study to lay the groundwork for an intended and organized decision-making process for managing warm-water habitat needed by endangered manatees to survive winters in Florida. Scientists and managers have prioritized (a) projecting how the network of warm-water sites will change over the next 50 years as warmed industrial discharges may expire and as flows of natural springs are reduced through redirection of water for human uses, and (b) mitigating such changes to prevent undue consequences to manatees. Given the complexities introduced by manatee ecology; agency organizational structure; shifting public demands; fluctuating resource availability; and managing within interacting cultural, social, political, and environmental contexts, it was clear that a structured decision process was needed. To help promote such a process, we collected information relevant to future decisions including maps of known and suspected warm-water sites and prototyped a characterization of sites and networks. We propose steps that would lead to models that might serve as core tools in manatee/warm-water decision-making, and we summarized topics relevant for informed decision-making (e.g., manatee spatial cognition, risk of cold-stress morbidity and mortality, and human dimensions). A major impetus behind this effort is to ensure proactively that robust modeling tools are available well in advance of the anticipated need for a critical management decision.

  1. Improving conservation of Florida manatees (Trichechus manatus latirostris): conceptualization and contributions toward a regional warm-water network management strategy for sustainable winter habitat.

    PubMed

    Flamm, Richard Owen; Reynolds, John Elliot; Harmak, Craig

    2013-01-01

    We used southwestern Florida as a case study to lay the groundwork for an intended and organized decision-making process for managing warm-water habitat needed by endangered manatees to survive winters in Florida. Scientists and managers have prioritized (a) projecting how the network of warm-water sites will change over the next 50 years as warmed industrial discharges may expire and as flows of natural springs are reduced through redirection of water for human uses, and (b) mitigating such changes to prevent undue consequences to manatees. Given the complexities introduced by manatee ecology; agency organizational structure; shifting public demands; fluctuating resource availability; and managing within interacting cultural, social, political, and environmental contexts, it was clear that a structured decision process was needed. To help promote such a process, we collected information relevant to future decisions including maps of known and suspected warm-water sites and prototyped a characterization of sites and networks. We propose steps that would lead to models that might serve as core tools in manatee/warm-water decision-making, and we summarized topics relevant for informed decision-making (e.g., manatee spatial cognition, risk of cold-stress morbidity and mortality, and human dimensions). A major impetus behind this effort is to ensure proactively that robust modeling tools are available well in advance of the anticipated need for a critical management decision.

  2. Improving conservation of Florida manatees (Trichechus manatus latirostris): conceptualization and contributions toward a regional warm-water network management strategy for sustainable winter habitat.

    PubMed

    Flamm, Richard Owen; Reynolds, John Elliot; Harmak, Craig

    2013-01-01

    We used southwestern Florida as a case study to lay the groundwork for an intended and organized decision-making process for managing warm-water habitat needed by endangered manatees to survive winters in Florida. Scientists and managers have prioritized (a) projecting how the network of warm-water sites will change over the next 50 years as warmed industrial discharges may expire and as flows of natural springs are reduced through redirection of water for human uses, and (b) mitigating such changes to prevent undue consequences to manatees. Given the complexities introduced by manatee ecology; agency organizational structure; shifting public demands; fluctuating resource availability; and managing within interacting cultural, social, political, and environmental contexts, it was clear that a structured decision process was needed. To help promote such a process, we collected information relevant to future decisions including maps of known and suspected warm-water sites and prototyped a characterization of sites and networks. We propose steps that would lead to models that might serve as core tools in manatee/warm-water decision-making, and we summarized topics relevant for informed decision-making (e.g., manatee spatial cognition, risk of cold-stress morbidity and mortality, and human dimensions). A major impetus behind this effort is to ensure proactively that robust modeling tools are available well in advance of the anticipated need for a critical management decision. PMID:23161252

  3. Response of shoal grass, Halodule wrightii, to extreme winter conditions in the Lower Laguna Madre, Texas

    USGS Publications Warehouse

    Hicks, D.W.; Onuf, C.P.; Tunnell, J.W.

    1998-01-01

    Effects of a severe freeze on the shoal grass, Halodule wrightii, were documented through analysis of temporal and spatial trends in below-ground biomass. The coincidence of the second lowest temperature (-10.6??C) in 107 years of record, 56 consecutive hours below freezing, high winds and extremely low water levels exposed the Laguna Madre, TX, to the most severe cold stress in over a century. H. wrightii tolerated this extreme freeze event. Annual pre- and post-freeze surveys indicated that below-ground biomass estimated from volume was Unaffected by the freeze event. Nor was there any post-freeze change in biomass among intertidal sites directly exposed to freezing air temperatures relative to subtidal sites which remained submerged during the freezing period.

  4. Warming combined with more extreme precipitation regimes modifies the water sources used by trees

    DOE PAGES

    Grossiord, Charlotte; Sevanto, Sanna; Dawson, Todd E.; Adams, Henry D.; Collins, Adam D.; Dickman, Lee T.; Newman, Brent D.; Stockton, Elizabeth A.; McDowell, Nate G.

    2016-09-09

    The persistence of vegetation under climate change will depend on a plant's capacity to exploit water resources. In addition, we analyzed water source dynamics in piñon pine and juniper trees subjected to precipitation reduction, atmospheric warming, and to both simultaneously.

  5. Madeira Extreme Floods: 2009/2010 Winter. Case study - 2nd and 20th of February

    NASA Astrophysics Data System (ADS)

    Pires, V.; Marques, J.; Silva, A.

    2010-09-01

    Floods are at world scale the natural disaster that affects a larger fraction of the population. It is a phenomenon that extends it's effects to the surrounding areas of the hydrographic network (basins, rivers, dams) and the coast line. Accordingly to USA FEMA (Federal Emergency Management Agency) flood can be defined as:"A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties from: Overflow of inland or tidal waters; Unusual and rapid accumulation or runoff of surface waters from any source; Mudflow; Collapse or subsidence of land along the shore of a lake or similar body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels that result in a flood as defined above." A flash flood is the result of intense and long duration of continuous precipitation and can result in dead casualties (i.e. floods in mainland Portugal in 1967, 1983 and 1997). The speed and strength of the floods either localized or over large areas, results in enormous social impacts either by the loss of human lives and or the devastating damage to the landscape and human infrastructures. The winter of 2009/2010 in Madeira Island was characterized by several episodes of very intense precipitation (specially in December 2009 and February 2010) adding to a new record of accumulated precipitation since there are records in the island. In February two days are especially rainy with absolute records for the month of February (daily records since 1949): 111mm and 97mm on the 2nd and 20th respectively. The accumulated precipitation ended up with the terrible floods on the 20th of February causing the lost of dozens of human lives and hundreds of millions of Euros of losses The large precipitation occurrences either more intense precipitation in a short period or less intense precipitation during a larger period are sometimes the precursor of

  6. Regional modeling sensitivity experiments for interpreting the UK Winter 2013-2014 extreme rain

    NASA Astrophysics Data System (ADS)

    Omrani, H.; Vautard, R.; Schaller, N.; Allen, M. R.

    2015-12-01

    During the winter 2013/2014, the UK saw heavy rainfalls associated with a succession of storms reaching Southern England causing widespread flooding, power cuts and major disruptions to transport. The January precipitation set a record for several rain gauge stations in Southern England. The aim of this study is to evaluate the contribution of the anthropogenic climate change, represented by a modification of the sea surface temperature (SST) on the January precipitation. For that, we conducted a sensitivity experiment by running a set of 108 four-months simulations using WRF model with 9 different physics and 12 different SST fields; 9 for the factual world and 99 for the counter-factual world. A spectral nudging technique was used here to ensure a same atmospheric circulation patterns for all the simulations. Therefore, only the thermodynamic effect is considered here. The analysis is focused on January precipitation over the southern England. Results show for 0,5°C SST difference over the Northern Atlantic, the precipitation in the factual simulations is between 0,4 and 8% higher than the precipitation in the counter-factual simulations depending on the physic. A validation test shows that this value is closer to 8% for the "best physic" simulation. It also show a strong spatial variability where in some region the precipitation is higher in the counter-factual world compared the factual world. Finally, a backward trajectories were calculated to evaluate the sensitivity of the moisture sources and air mass trajectories to the SST in the factual and the counter-factual world.

  7. Changes in sub-daily precipitation extremes in a global climate model with super-parameterization under CO2 warming

    NASA Astrophysics Data System (ADS)

    Khairoutdinov, Marat; Zhou, Xin

    2015-04-01

    Virtually all of the projections for future change of extreme precipitation statistics under CO2 warming have been made using global climate models (GCMs) in which clouds and, in particular, convective cloud systems are not explicitly resolved, but rather parameterized. In our study, a different kind of a GCM, a super-parameterized Community Atmosphere Model (SP-CAM), is employed. In SP-CAM, all the conventional cloud parameterizations are replaced with a small-domain cloud resolving model (CRM), called super-parameterization (SP). The SP is embedded in each grid column of the host GCM. The resolution of each embedded CRM is 4 km, which is generally sufficient to explicitly represent deep convection, which is mostly responsible for extreme precipitation events. In this study, we use the SP-CAM to contrast to the present and to conventional climate model, CAM, the sub-daily extreme precipitation statistics in response to the sea-surface temperatures (SSTs) and CO2 levels as projected for the end of 21st century in response to the IPCC AR5 RCP8.5 emission scenario. Different mechanisms for extreme precipitation changes are discussed.

  8. Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

    NASA Astrophysics Data System (ADS)

    Dong, Buwen; Sutton, Rowan T.; Shaffrey, Len

    2016-05-01

    Analysis of observations indicates that there was a rapid increase in summer (June-August) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This study focuses on understanding causes of the rapid summer warming and associated temperature extreme changes. A set of experiments using the atmospheric component of the state-of-the-art HadGEM3 global climate model have been carried out to quantify relative roles of changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and anthropogenic aerosols (AAer). Results indicate that the model forced by changes in all forcings reproduces many of the observed changes since the mid-1990s over Western Europe. Changes in SST/SIE explain 62.2 ± 13.0 % of the area averaged seasonal mean warming signal over Western Europe, with the remaining 37.8 ± 13.6 % of the warming explained by the direct impact of changes in GHGs and AAer. Results further indicate that the direct impact of the reduction of AAer precursor emissions over Europe, mainly through aerosol-radiation interaction with additional contributions from aerosol-cloud interaction and coupled atmosphere-land surface feedbacks, is a key factor for increases in annual hottest day temperature and in frequency of summer days. It explains 45.5 ± 17.6 % and 40.9 ± 18.4 % of area averaged signals for these temperature extremes. The direct impact of the reduction of AAer precursor emissions over Europe acts to increase DTR locally, but the change in DTR is countered by the direct impact of GHGs forcing. In the next few decades, greenhouse gas concentrations will continue to rise and AAer precursor

  9. [Effects of Warming and Straw Application on Soil Respiration and Enzyme Activity in a Winter Wheat Cropland].

    PubMed

    Chen, Shu-tao; Sang, Lin; Zhang, Xu; Hu, Zheng-hua

    2016-02-15

    In order to investigate the effects of warming and straw application on soil respiration and enzyme activity, a field experiment was performed from November 2014 to May 2015. Four treatments, which were control (CK), warming, straw application, and warming and straw application, were arranged in field. Seasonal variability in soil respiration, soil temperature and soil moisture for different treatments were measured. Urease, invertase, and catalase activities for different treatments were measured at the elongation, booting, and anthesis stages. The results showed that soil respiration in different treatments had similar seasonal variation patterns. Seasonal mean soil respiration rates for the CK, warming, straw application, and warming and straw application treatments were 1.46, 1.96, 1.92, and 2.45 micromol x (m2 x s)(-1), respectively. ANOVA indicated that both warming and straw applications significantly (P < 0.05) enhanced soil respiration compared to the control treatment. The relationship between soil respiration and soil temperature in different treatments fitted with the exponential regression function. The exponential regression functions explained 34.3%, 28.1%, 24.6%, and 32.0% variations of soil respiration for CK, warming, straw application, and warming and straw application treatments, respectively. Warming and straw applications significantly (P < 0.05) enhanced urease, invertase, and catalase activities compared to CK. The relationship between soil respiration and urease activity fitted with a linear regression function, with the P value of 0.061. The relationship between soil respiration and invertase (P = 0.013), and between soil respiration and catalase activity (P = 0.002) fitted well with linear regression functions.

  10. [Effects of Warming and Straw Application on Soil Respiration and Enzyme Activity in a Winter Wheat Cropland].

    PubMed

    Chen, Shu-tao; Sang, Lin; Zhang, Xu; Hu, Zheng-hua

    2016-02-15

    In order to investigate the effects of warming and straw application on soil respiration and enzyme activity, a field experiment was performed from November 2014 to May 2015. Four treatments, which were control (CK), warming, straw application, and warming and straw application, were arranged in field. Seasonal variability in soil respiration, soil temperature and soil moisture for different treatments were measured. Urease, invertase, and catalase activities for different treatments were measured at the elongation, booting, and anthesis stages. The results showed that soil respiration in different treatments had similar seasonal variation patterns. Seasonal mean soil respiration rates for the CK, warming, straw application, and warming and straw application treatments were 1.46, 1.96, 1.92, and 2.45 micromol x (m2 x s)(-1), respectively. ANOVA indicated that both warming and straw applications significantly (P < 0.05) enhanced soil respiration compared to the control treatment. The relationship between soil respiration and soil temperature in different treatments fitted with the exponential regression function. The exponential regression functions explained 34.3%, 28.1%, 24.6%, and 32.0% variations of soil respiration for CK, warming, straw application, and warming and straw application treatments, respectively. Warming and straw applications significantly (P < 0.05) enhanced urease, invertase, and catalase activities compared to CK. The relationship between soil respiration and urease activity fitted with a linear regression function, with the P value of 0.061. The relationship between soil respiration and invertase (P = 0.013), and between soil respiration and catalase activity (P = 0.002) fitted well with linear regression functions. PMID:27363163

  11. Design and quantification of an extreme winter storm scenario for emergency preparedness and planning exercises in California

    USGS Publications Warehouse

    Dettinger, M.D.; Martin, Ralph F.; Hughes, M.; Das, T.; Neiman, P.; Cox, D.; Estes, G.; Reynolds, D.; Hartman, R.; Cayan, D.; Jones, L.

    2012-01-01

    The USGS Multihazards Project is working with numerous agencies to evaluate and plan for hazards and damages that could be caused by extreme winter storms impacting California. Atmospheric and hydrological aspects of a hypothetical storm scenario have been quantified as a basis for estimation of human, infrastructure, economic, and environmental impacts for emergency-preparedness and flood-planning exercises. In order to ensure scientific defensibility and necessary levels of detail in the scenario description, selected historical storm episodes were concatentated to describe a rapid arrival of several major storms over the state, yielding precipitation totals and runoff rates beyond those occurring during the individual historical storms. This concatenation allowed the scenario designers to avoid arbitrary scalings and is based on historical occasions from the 19th and 20th Centuries when storms have stalled over the state and when extreme storms have arrived in rapid succession. Dynamically consistent, hourly precipitation, temperatures, barometric pressures (for consideration of storm surges and coastal erosion), and winds over California were developed for the so-called ARkStorm scenario by downscaling the concatenated global records of the historical storm sequences onto 6- and 2-km grids using a regional weather model of January 1969 and February 1986 storm conditions. The weather model outputs were then used to force a hydrologic model to simulate ARkStorm runoff, to better understand resulting flooding risks. Methods used to build this scenario can be applied to other emergency, nonemergency and non-California applications. ?? 2011 The Author(s).

  12. Extreme collisions between planetesimals as the origin of warm dust around a Sun-like star.

    PubMed

    Song, Inseok; Zuckerman, B; Weinberger, Alycia J; Becklin, E E

    2005-07-21

    The slow but persistent collisions between asteroids in our Solar System generate a tenuous cloud of dust known as the zodiacal light (because of the light the dust reflects). In the young Solar System, such collisions were more common and the dust production rate should have been many times larger. Yet copious dust in the zodiacal region around stars much younger than the Sun has rarely been found. Dust is known to orbit around several hundred main-sequence stars, but this dust is cold and comes from a Kuiper-belt analogous region out beyond the orbit of Neptune. Despite many searches, only a few main-sequence stars reveal warm (> 120 K) dust analogous to zodiacal dust near the Earth. Signs of planet formation (in the form of collisions between bodies) in the regions of stars corresponding to the orbits of the terrestrial planets in our Solar System have therefore been elusive. Here we report an exceptionally large amount of warm, small, silicate dust particles around the solar-type star BD+20,307 (HIP 8920, SAO 75016). The composition and quantity of dust could be explained by recent frequent or huge collisions between asteroids or other 'planetesimals' whose orbits are being perturbed by a nearby planet. PMID:16034411

  13. Statistical Downscaling of Gusts During Extreme European Winter Storms Using Radial-Basis-Function Networks

    NASA Astrophysics Data System (ADS)

    Voigt, M.; Lorenz, P.; Kruschke, T.; Osinski, R.; Ulbrich, U.; Leckebusch, G. C.

    2012-04-01

    Winterstorms and related gusts can cause extensive socio-economic damages. Knowledge about the occurrence and the small scale structure of such events may help to make regional estimations of storm losses. For a high spatial and temporal representation, the use of dynamical downscaling methods (RCM) is a cost-intensive and time-consuming option and therefore only applicable for a limited number of events. The current study explores a methodology to provide a statistical downscaling, which offers small scale structured gust fields from an extended large scale structured eventset. Radial-basis-function (RBF) networks in combination with bidirectional Kohonen (BDK) maps are used to generate the gustfields on a spatial resolution of 7 km from the 6-hourly mean sea level pressure field from ECMWF reanalysis data. BDK maps are a kind of neural network which handles supervised classification problems. In this study they are used to provide prototypes for the RBF network and give a first order approximation for the output data. A further interpolation is done by the RBF network. For the training process the 50 most extreme storm events over the North Atlantic area from 1957 to 2011 are used, which have been selected from ECMWF reanalysis datasets ERA40 and ERA-Interim by an objective wind based tracking algorithm. These events were downscaled dynamically by application of the DWD model chain GME → COSMO-EU. Different model parameters and their influence on the quality of the generated high-resolution gustfields are studied. It is shown that the statistical RBF network approach delivers reasonable results in modeling the regional gust fields for untrained events.

  14. Intensification of seasonal temperature extremes prior to the 2°C global warming target

    NASA Astrophysics Data System (ADS)

    Anderson, B. T.

    2011-12-01

    Given current international efforts to limit human-induced global-mean near-surface temperature increases to 2°C, relative to the pre-industrial era, there is an interest in determining what unavoidable impacts to physical, biological, and socio-economic systems might occur even if this target were met. In our research we show that substantial fractions of the globe could experience seasonal-mean temperature extremes with unprecedented regularity, even if the global-mean temperature remains below the 2°C target currently envisioned. These results have significant implications for agriculture and crop yield; disease and human health; and ecosystems and biodiversity. To obtain these results, we first develop a novel method for combining numerical-model estimates of near-term increases in grid-point temperatures with stochastically generated anomalies derived from high-resolution observations during the last half of the 20th century. This method has practical advantages because it generates results at fine spatial resolution without relying on computationally-intensive regional-model experiments; it explicitly incorporates information derived from the observations regarding interannual-to-decadal variations in seasonal-mean temperatures; and it includes the generation of thousands of realizations of the possible impacts of a global mean temperature increase on local occurrences of hot extremes. Using this method we find that even given the "committed" future global-mean temperature increase of 0.6°C (1.4°C relative to the pre-industrial era) historical seasonal-mean temperature extremes will be exceeded in at least half of all years-equivalently, the historical extreme values will become the norm-for much of Africa, the southeastern and central portions of Asia, Indonesia, and the Amazon. Should the global-mean temperature increase reach 2°C (relative to the pre-industrial era), it is more likely than not that these same regions, along with large portions of

  15. Magnitude of extreme heat waves in present climate and their projection in a warming world

    NASA Astrophysics Data System (ADS)

    Russo, Simone; Dosio, Alessandro; Graversen, Rune G.; Sillmann, Jana; Carrao, Hugo; Dunbar, Martha B.; Singleton, Andrew; Montagna, Paolo; Barbola, Paulo; Vogt, Jürgen V.

    2014-11-01

    An extreme heat wave occurred in Russia in the summer of 2010. It had serious impacts on humans and natural ecosystems, it was the strongest recorded globally in recent decades and exceeded in amplitude and spatial extent the previous hottest European summer in 2003. Earlier studies have not succeeded in comparing the magnitude of heat waves across continents and in time. This study introduces a new Heat Wave Magnitude Index that can be compared over space and time. The index is based on the analysis of daily maximum temperature in order to classify the strongest heat waves that occurred worldwide during the three study periods 1980-1990, 1991-2001, and 2002-2012. In addition, multimodel ensemble outputs from the Coupled Model Intercomparison Project Phase 5 are used to project future occurrence and severity of heat waves, under different Representative Concentration Pathways, adopted by the Intergovernmental Panel on Climate Change for its Fifth Assessment Report (AR5). Results show that the percentage of global area affected by heat waves has increased in recent decades. Moreover, model predictions reveal an increase in the probability of occurrence of extreme and very extreme heat waves in the coming years, in particular, by the end of this century, under the most severe IPCC AR5 scenario, events of the same severity as that in Russia in the summer of 2010 will become the norm and are projected to occur as often as every 2 years for regions such as southern Europe, North America, South America, Africa, and Indonesia.

  16. Deeper winter snow reduces ecosystem C losses but increases the global warming potential of Arctic tussock tundra over the growing season.

    NASA Astrophysics Data System (ADS)

    Blanc-Betes, E.; Welker, J. M.; Gomez-Casanovas, N.; Gonzalez-Meler, M. A.

    2015-12-01

    Arctic winter precipitation is projected to increase globally over the next decades, spatial variability encompassing areas with increases and decreases in winter snow. Changes in winter precipitation strongly affect C dynamics in Arctic systems and may lead to major positive climate forcing feedbacks. However, impacts of predicted changes in snowfall and accumulation on the rate and form of C fluxes (CO2 and CH4) and associated forcing feedbacks from Arctic tundra remain uncertain. We investigated how changes in winter precipitation affect net ecosystem CO2 and CH4 fluxes and budgets of moist acidic tundra in an 18-yrs snow fence experiment over a complete growing season at Toolik Lake, AK. Arctic tundra under ambient winter precipitation (CTL) was a net source of CO2 and CH4, yielding net C losses over the growing season. Reduced snow (-15-30% snow depth; RS) switched the system to a net CO2 sink mostly by limiting SOC decomposition within colder soils. Snow additions progressively reduced net ecosystem CO2 losses compared to CTL, switching the system into a weaker net CO2 source with medium additions (+20-45% snow depth; MS) and into a small net CO2 sink with high additions (+70-100% snow depth; HS). Increasingly wetter soils with snow additions constrained the temperature sensitivity of aerobic decomposition and favored the anaerobic metabolism, buffering ecosystem CO2 losses despite substantial soil warming. Accordingly, Arctic tundra switched from a sustained CH4 sink at RS site to an increasingly stronger CH4 source with snow additions. Accounting for both CO2 and CH4, the RS site became a net C sink over the growing season, overall reducing the global warming potential (CO2 equiv.; GWP) of the system relative to CTL. Snow additions progressively reduced net C losses at the MS site compared to CTL and the system transitioned into a net C sink at HS plots, partly due to the slower metabolism of anaerobic decomposition. However, given the greater radiative

  17. Attribution of the Recent Winter Arctic warming and Sea-Ice Decline with Observation-based Data and Coupled Climate Model Simulations

    NASA Astrophysics Data System (ADS)

    Lee, S.; Park, D. S. R.; Feldstein, S. B.; Franzke, C. L. E.

    2015-12-01

    Wintertime Arctic sea ice extent has been declining since the late 20th century, particularly over the Atlantic sector that encompasses the Barents-Kara Seas and Baffin Bay. This sea-ice decline is attributable to various Arctic environmental changes, such as enhanced downward infrared radiation (IR), preseason sea-ice reduction, enhanced inflow of warm Atlantic water into the Arctic Ocean, and sea-ice export. However, their relative contributions are uncertain. Utilizing ERA-Interim reanalysis and satellite-based data, it is shown here that a positive trend of downward IR accounts for nearly half of the sea-ice concentration (SIC) decline during the 1979-2011 winter over the Atlantic sector. Furthermore, we find that the Arctic downward IR increase is driven by horizontal atmospheric water flux and warm air advection into the Arctic, and not by evaporation and surface heat flux from the Arctic Ocean. These horizontal heat fluxes are linked to La-Nina-like tropical convection. In all CMIP5 climate models that are analyzed here, high pattern correlations are found between the surface air temperature trend and downward IR trend. However, there are two groups of CMIP5 models: one with small correlations between the Arctic surface air temperature trend and the surface heat flux trend (Group 1), and the other with large correlations (Group 2) between the same two variables. There is evidence that the Group 1 models are consistent with the aforementioned observation-based finding that the Arctic warming is closely related to large-scale circulation changes. In contrast, the Group 2 models are at odds with this observation in that their Arctic warming is more closely tied to surface heat fluxes than with the large-scale circulation change. Interestingly, while Group 1 models have a warm or weak bias, Group 2 models have large cold biases in the Arctic. This difference suggests that deficiencies that cause the cold bias of the mean state may contribute to the surface heat

  18. Understanding future projected changes and historical trends in extreme climate and streamflow events in warm boreal permafrost basins of Interior Alaska

    NASA Astrophysics Data System (ADS)

    Bennett, K. E.; Cherry, J. E.; Walsh, J. E.; Hinzman, L. D.

    2014-12-01

    Changes in future and historical extreme events may have disastrous consequences in vulnerable systems such as the warm- permafrost-dominated Interior region of Alaska. This paper presents a study examining extreme hydro-climate events (temperature, precipitation and streamflow) in Interior Alaskan watersheds, focused on results from Fairbanks, Alaska, located within the Chena River basin. Results are presented for an ensemble of global climate models (GCMs) and emission scenarios, run through to 2100. GCMs, selected for performance over the Alaskan domain, project the largest increases in minimum daily minimum temperature (TNn), compared to maximum daily maximum temperature (TXx), in the winter and spring at the Fairbanks Airport station. The increases in TNn and TXx are much larger (two to four times) than the across GCM standard deviations, indicating robustness in the projected changes. Statistically significant increases in five-day maximum precipitation are also projected to occur by the 2080s, with the largest increases expected for the summer and fall seasons. Streamflow projections provided by running the Sacramento Soil Moisture Accounting model, coupled with the SNOW17 snow model, are analyzed using a generalized extreme value (GEV) theorem and nonparametric trend approach. The Chena River basin exhibits linear nonstationary increases in maximum and minimum annual streamflow projected by the 2080s under both the RCP 4.5 and RCP 8.5 scenarios, minimized by the Akaike Information Criteria statistic, corrected for small sample sizes. Changes are indicative of increased flow volumes in the summer and fall, following precipitation changes projected to occur during these seasons. These changes are distinct from trends and GEV analysis performed on the historical streamflow series, which indicate declining flows associated with the loss of snowpack observed as a statistically significant reduction in relative flow volume (-49%, p-value 0.01) during the May

  19. Application of an extreme winter storm scenario to identify vulnerabilities, mitigation options, and science needs in the Sierra Nevada mountains, USA

    USGS Publications Warehouse

    Albano, Christine M.; Dettinger, Michael; McCarthy, Maureen; Schaller, Kevin D.; Wellborn, Toby; Cox, Dale A.

    2016-01-01

    In the Sierra Nevada mountains (USA), and geographically similar areas across the globe where human development is expanding, extreme winter storm and flood risks are expected to increase with changing climate, heightening the need for communities to assess risks and better prepare for such events. In this case study, we demonstrate a novel approach to examining extreme winter storm and flood risks. We incorporated high-resolution atmospheric–hydrologic modeling of the ARkStorm extreme winter storm scenario with multiple modes of engagement with practitioners, including a series of facilitated discussions and a tabletop emergency management exercise, to develop a regional assessment of extreme storm vulnerabilities, mitigation options, and science needs in the greater Lake Tahoe region of Northern Nevada and California, USA. Through this process, practitioners discussed issues of concern across all phases of the emergency management life cycle, including preparation, response, recovery, and mitigation. Interruption of transportation, communications, and interagency coordination were among the most pressing concerns, and specific approaches for addressing these issues were identified, including prepositioning resources, diversifying communications systems, and improving coordination among state, tribal, and public utility practitioners. Science needs included expanding real-time monitoring capabilities to improve the precision of meteorological models and enhance situational awareness, assessing vulnerabilities of critical infrastructure, and conducting cost–benefit analyses to assess opportunities to improve both natural and human-made infrastructure to better withstand extreme storms. Our approach and results can be used to support both land use and emergency planning activities aimed toward increasing community resilience to extreme winter storm hazards in mountainous regions.

  20. Extreme coastal storms along the north coast of Ireland: hydrodynamic forcing and beach response during the winter seasons of 2013/14 and 2014/15

    NASA Astrophysics Data System (ADS)

    Loureiro, Carlos; Marianne, O'Connor; Guisado-Pintado, Emilia; Jackson, Derek; Cooper, Andrew

    2016-04-01

    The increase in storminess (frequency, duration and magnitude) and the occurrence of extreme coastal storms partly associated with climate change, represent pressing concerns for coastal communities in many regions globally. The Atlantic seaboard of Europe has recently experienced record-breaking winter seasons, particularly in Ireland and the UK, where the 2013/14 winter was characterised as the stormiest on record according to measured levels of total precipitation, extreme wind speeds, and particularly the frequency and intensity of cyclone activity. The enhanced cyclone activity during 2013/14 has resulted in unprecedented sequences of extreme water levels and energetic waves and gave rise to widespread coastal erosion and flooding, setting new benchmarks for coastal analysis and offered a glimpse of future storm impact scenarios. A regional analysis of hydrodynamic forcing along the north coast of Ireland over the last two extended winter seasons (October to March) has revealed that, although 2013/14 was indeed characterised by an exceptional frequency and intensity of coastal storms, the 2014/15 extended winter was significantly stormier. Not only was the number of individual storm events higher, but also the duration and intensity was greater, including record values of offshore significant wave height. The geomorphic response along the sandy coastal stretches of the north coast of Ireland, evaluated from morphological change at a diverse group of beach sites, revealed considerable differences in beach erosion and actual shoreline response. Variability in beach changes during these two extreme winter seasons is attributed to a variety of factors. These include localised coastal orientation relative to particular storm tracks, the embayed and highly compartmentalised setting of most of the beaches, as well as site-specific morphodynamic mechanisms such as large rip-current cells forcing the onset and/or reactivation of erosional hotspots. Such heterogeneous

  1. Changing precipitation extremes in a warming climate: A basis for design flood estimation

    NASA Astrophysics Data System (ADS)

    Wasko, Conrad; Sharma, Ashish

    2016-04-01

    The potential for increasing intensity of future rainfall events has significant implications for flooding and the design of infrastructure. However the questions of how precipitation will change in the future, how important these changes are to flooding, and how engineers incorporate these changes into hydrologic design remain as open questions. In the absence of reliable point based estimates of how precipitation will change, many studies investigate the historical relationship between rainfall intensity and temperature as a proxy for what may happen in a warmer climate. Much of the research to date has focussed on changing precipitation intensity, however, temporal and spatial patterns of precipitation are just as important. Here we link higher temperatures to changes in temporal and spatial patterns of extreme precipitation events. We show, using observed high quality precipitation records from Australia covering all major climatic zones, that storms are intensifying in both time and space resulting in a greater potential for flooding especially in urban locales around the world. Given that precipitation and antecedent conditions are changing, and, the impacts to flooding are significant, methods of incorporating these changes in catchment modelling are required. Continuous simulation offers a natural flexibility to incorporate the many correlated changes in precipitation that may occur in a future climate. An argument for such a framework using existing continuous simulation alternatives is articulated in concluding this presentation.

  2. Chemical forms and sources of extremely high nitrate and chloride in winter aerosol pollution in the Kanto Plain of Japan

    NASA Astrophysics Data System (ADS)

    Kaneyasu, Naoki; Yoshikado, Hiroshi; Mizuno, Tateki; Sakamoto, Kazuhiko; Soufuku, Masataka

    The spatial distributions, chemical forms, and potential sources have been investigated for extremely high concentrations of Cl - and NO -3 in aerosols collected during an extensive study for winter pollution episodes in the Kanto Plain of Japan. Air monitoring are conducted at 10 sites including the rooftops of skyscrapers during two measurement periods in November-December 1991. Similarity in the diurnal variation patterns of NO -3 among the sampling sites suggests that its precursor HNO 3 is formed by reactions in the atmosphere, while difference in the maximum concentration of Cl - between the sites indicates the presence of local sources. Measurements at ground level and on the rooftops of skyscrapers show that the pronounced diurnal variations of both components are phenomena occurring in the layer extending from the ground surface to at least 200 m height. Intensified measurements at two ground sites indicate that (1) NO -3 and non sea-salt Cl - are predominantly in the fine mode, (2) [NO -3] + [Cl -] and [NH +4] are in equivalence, (3) gaseous HCl, HNO 3, and NH 3 are in equilibrium with particulate NH 4Cl and NH 4NO 3. From these results, it is concluded that measured Cl - and NO -3 are predominantly in the form of NH 4Cl and NH 4NO 3, respectively. The behavior of peroxyacetyl nitrate (PAN) indicates that HNO 3, the precursor of NO -3, is produced in the photochemical reactions of the NO x-hydrocarbons system. The elevated concentration of NO 2 measured simultaneously in the pollution episodes is regarded as an alternative form of O 3 produced in photochemical reactions. As the precursor of Cl - in aerosols, sources of HCl are discussed, and the emission from incineration of domestic and industrial waste in the area is estimated.

  3. Investigation of the structure and stability of the lower atmosphere by microwave ground-based sensing over Nizhniy Novgorod, Russia during abnormally warm winter 2013 - 2014

    NASA Astrophysics Data System (ADS)

    Karashtin, Dmitriy; Berezin, Evgeny; Kulikov, Mikhail; Feigin, Alexander

    2014-05-01

    The monitoring of the lower atmosphere structure and stability is required for studying the processes of the convection in the atmosphere, determining the mutual influence of global climate change trends and the current state of regional climate systems, which have an impact on the appearance of dangerous meteorological events (heavy rains, thunderstorms, hail, floods, squalls, tornadoes, etc). There are many methods of measuring structure of the atmosphere: contact (rocket and balloon), contactless - active (lidar) and passive (radiometric), with the placement of the instrumentation on the satellite, airplanes and the Earth's surface (ground-based). For the convection processes study in order to predict dangerous meteorological events the ground-based radiometric sensing of the structure of the lower atmosphere seems to be the most suitable due to higher time and spatial resolution. This report discusses the peculiarities of the structure of the lower atmosphere over Nizhniy Novgorod, Russia during the abnormally warm winter 2013 - 2014 retrieved from measurements by radiometric complex HATPRO-G3 by Radiometer Physics GmbH. This complex gives vertical thermal and water vapor profiles of the lower atmosphere (0 - 10 km) with time resolution of a few minutes, horizontally resolution of about 10 kilometers and vertically resolution of about 100 meters. The analysis of the structure and stability of the lower atmosphere is based on the vertical distribution of virtual potential temperature derived from these measurements under the hydrostatic approximation. Also the comparison of the results for the abnormally winter 2013 - 2014 and the data computed from the Weather Research and Forecasting (WRF) Model (http://www.wrf-model.org) for winter 2011 - 2012 is discussed.

  4. Impact of Anthropogenic Land Cover Change on Warm Temperature Extremes : the summer 2003 heat waves as a testbed

    NASA Astrophysics Data System (ADS)

    Stéfanon, M.

    2013-12-01

    Events similar to the 2003 mega heat wave will be likely more frequent, intense and longer by the end of the 21st century owing to enhanced atmospheric greenhouse-gas concentrations. Policies for climate mitigation privileges carbon sequestration techniques while land cover change (LCC) may be a preferred alternative in terms of environmental impact, where geography permits. Biogeophysical factors such as albedo, evapotranspiration, and surface roughness may have locally the potential to offset the biogeochemical impact of increased greenhouse-gas. However, so far the set of existing (but not consistent) LCC impact studies conducted in the Mediterranean have contradictory results on summer temperature (cooling or warming). Using the Model of the Regional Coupled Earth system (MORCE), the impact of an afforestation scenario (POT) is conducted for both 2002 and 2003 years, and compared to an agricultural scenario (CUR). The favorable meteorological conditions in spring 2003 fasten the development of agricultural vegetation in CUR compared to a) conditions in 2002, and b) to the development of trees in POT. This greater photosynthetic capacity of crops, followed by larger evapotranspiration rates, dampens the extreme values of temperature from April to the end of June 2003 (locally by 3°C) and more specifically during the June heat-wave (locally by 1.6°C). It contributes to increase the differences between POT and CUR in 2003 compared to 2002. In July vegetation starts to get limited by soil moisture, and agricultural plants are most affected than trees because of their shallower roots. From early July to October, trees are not too water limited. They can still evaporate, while water stress in CUR makes croplands contribute to enhance the warm summer temperatures, especially in 2003. The very hot summer 2003 July-August temperatures are therefore amplified (resp. dampened) by the presence of crops (resp. trees) in CUR (resp. POT). However this cooling capacity of

  5. Influences of Meteorological Anomalies on An Extreme Winter Haze Event in Beijing - A Numerical Study Using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Wang, Tao; Zha, Qiaozhi; Lv, Menyao; Zhang, Qiang

    2014-05-01

    Beijing has made great efforts to reduce anthropogenic emissions for the last decade and its air quality, consequently, does show a slight improvement since 2007 as reflected by the decreasing Air Pollution Index (API) trend. However, during the January 2013, this megacity was frequently shrouded by heavy haze and the PM2.5 observed in an urban site was higher than 75 μg m-3for two thirds of that month. On 12th January, an unprecedented haze event assaulted Beijing with the daily PM2.5 soared to 568.5 μg m-3 and API hit the upper limit. Through the analysis of historical meteorological data, we found that Beijing experienced the lowest average wind speed and the highest relative humidity (RH) in this January since 2000 and the frequency of prevailing northerly winter winds was abnormally low. We suggested that the high PM2.5 levels during this month including the extreme haze were mainly attributed to the climate anomalies in wind and RH. A series of simulations using a coupled meteorology-chemistry model (WRF-Chem) was used to study the role of the unique climate anomalies played in the episode as a case. The unusual week winds at surface and strong southerly winds at the 300-900 m layer created a strong temperature inversion and thus humidity and pollutants were trapped within the shallow boundary layer beneath the inversion, which was the main reason for the episode. Sensitivity simulations suggested that the local emission was the major contributor at the surface (40 m) whereas the regional contribution dominated at the upper layer (40-1500 m). Emergency and more stringent long-term emission controls should be applied in Beijing and surrounding provinces to prevent severe pollutions in case similar anomalous meteorological conditions occur again. During the episode, both surface weather pattern and transport pathway showed unique behaviors under the climate anomalies. The transport pathway even extended from the East China Plain, indicating that emission

  6. Contribution of the land-use forcing to the increase in risk of warm extreme events since 1850 over North America from constrained CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Lejeune, Quentin; Davin, Edouard; Seneviratne, Sonia

    2016-04-01

    During the industrial period, large areas of North America experienced a reduction in forest cover and an expansion of agricultural areas. There is indication that this has affected the intensity and frequency of temperature extremes through changes in biophysical land surface properties (Christidis et al., 2013, Pitman et al., 2012). However, it has never been addressed in the context of a multi-model transient experiment ensemble. Here we intend to constrain CMIP5 models with observations in order to assess the contribution of historical land-cover changes (LCC) to changes in the risk of warm extreme events over North America. We have retained only six models from the CMIP5 ensemble that can reproduce the local warming effect of deforestation during daytime, which was identified in present-day observations of the impact of deforestation on mean summer temperature (Lee et al, 2011). As for its observed cooling effect during nighttime, we kept the sole model that is able to simulate it. Using a framework derived from the Fraction of Attributable Risk methodology, we have then quantified by how much the increase in risk of getting a particular extreme event driven by increased greenhouse gas concentrations (GHG) was damped or amplified over areas which were largely affected by LCC, compared to surrounding ones that experienced few LCC over the same period. We find that the constrained model ensemble indicates an amplification by between 10 and more than 100% by local LCC of the increase in risk of occurrence of a warm extreme event corresponding to the 90th percentile during the pre-industrial period, depending on the model. This amplification factor gets higher for more extreme events, rising to at least 20% for the 995th permille. Regarding nighttime temperatures, the retained model indicates that historical LCC have locally more than cancelled the effect of increased GHG concentrations on the frequency of warm extreme events corresponding to between the 90th

  7. Response of precipitation extremes to idealized global warming in an aqua-planet climate model: Towards robust projection across different horizontal resolutions

    SciTech Connect

    Li, F.; Collins, W.D.; Wehner, M.F.; Williamson, D.L.; Olson, J.G.

    2011-04-15

    Current climate models produce quite heterogeneous projections for the responses of precipitation extremes to future climate change. To help understand the range of projections from multimodel ensembles, a series of idealized 'aquaplanet' Atmospheric General Circulation Model (AGCM) runs have been performed with the Community Atmosphere Model CAM3. These runs have been analysed to identify the effects of horizontal resolution on precipitation extreme projections under two simple global warming scenarios. We adopt the aquaplanet framework for our simulations to remove any sensitivity to the spatial resolution of external inputs and to focus on the roles of model physics and dynamics. Results show that a uniform increase of sea surface temperature (SST) and an increase of low-to-high latitude SST gradient both lead to increase of precipitation and precipitation extremes for most latitudes. The perturbed SSTs generally have stronger impacts on precipitation extremes than on mean precipitation. Horizontal model resolution strongly affects the global warming signals in the extreme precipitation in tropical and subtropical regions but not in high latitude regions. This study illustrates that the effects of horizontal resolution have to be taken into account to develop more robust projections of precipitation extremes.

  8. Response of precipitation extremes to global warming in an aqua-planet climate model: towards robust projection from regional to global scales

    NASA Astrophysics Data System (ADS)

    Li, F.; Collins, W.; Wehner, M. F.; Williamson, D.; Olson, J.

    2010-12-01

    Robust projection of precipitation extremes is essential for human society to prepare for future climate change. To understand the inconsistencies of the projections across the climate models, a series of idealized “aquaplanet” AGCM runs have been performed with CAM3 to investigate the effects of horizontal resolution on precipitation extreme projections under two simple global warming scenarios. The absence of orography helps diagnose the response of the physics responsible for extreme rainfall to change with resolution. Results show that a uniform increase of sea surface temperature (SST) and an increase of low-to-high latitude SST gradient both lead to increase of precipitation and precipitation extremes for most latitudes. The perturbed SSTs generally have stronger impacts on precipitation extremes compared with mean precipitation. Model horizontal-resolution strongly affects the global warming signals in the extreme precipitation in the low-mid latitudes, but not in high latitude regions. This study illustrates the need for resolution-invariant treatment of atmospheric processes.

  9. Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015-2016.

    PubMed

    Jiménez-Muñoz, Juan C; Mattar, Cristian; Barichivich, Jonathan; Santamaría-Artigas, Andrés; Takahashi, Ken; Malhi, Yadvinder; Sobrino, José A; Schrier, Gerard van der

    2016-09-08

    The El Niño-Southern Oscillation (ENSO) is the main driver of interannual climate extremes in Amazonia and other tropical regions. The current 2015/2016 EN event was expected to be as strong as the EN of the century in 1997/98, with extreme heat and drought over most of Amazonian rainforests. Here we show that this protracted EN event, combined with the regional warming trend, was associated with unprecedented warming and a larger extent of extreme drought in Amazonia compared to the earlier strong EN events in 1982/83 and 1997/98. Typical EN-like drought conditions were observed only in eastern Amazonia, whilst in western Amazonia there was an unusual wetting. We attribute this wet-dry dipole to the location of the maximum sea surface warming on the Central equatorial Pacific. The impacts of this climate extreme on the rainforest ecosystems remain to be documented and are likely to be different to previous strong EN events.

  10. Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015-2016.

    PubMed

    Jiménez-Muñoz, Juan C; Mattar, Cristian; Barichivich, Jonathan; Santamaría-Artigas, Andrés; Takahashi, Ken; Malhi, Yadvinder; Sobrino, José A; Schrier, Gerard van der

    2016-01-01

    The El Niño-Southern Oscillation (ENSO) is the main driver of interannual climate extremes in Amazonia and other tropical regions. The current 2015/2016 EN event was expected to be as strong as the EN of the century in 1997/98, with extreme heat and drought over most of Amazonian rainforests. Here we show that this protracted EN event, combined with the regional warming trend, was associated with unprecedented warming and a larger extent of extreme drought in Amazonia compared to the earlier strong EN events in 1982/83 and 1997/98. Typical EN-like drought conditions were observed only in eastern Amazonia, whilst in western Amazonia there was an unusual wetting. We attribute this wet-dry dipole to the location of the maximum sea surface warming on the Central equatorial Pacific. The impacts of this climate extreme on the rainforest ecosystems remain to be documented and are likely to be different to previous strong EN events. PMID:27604976

  11. Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015–2016

    PubMed Central

    Jiménez-Muñoz, Juan C.; Mattar, Cristian; Barichivich, Jonathan; Santamaría-Artigas, Andrés; Takahashi, Ken; Malhi, Yadvinder; Sobrino, José A.; Schrier, Gerard van der

    2016-01-01

    The El Niño-Southern Oscillation (ENSO) is the main driver of interannual climate extremes in Amazonia and other tropical regions. The current 2015/2016 EN event was expected to be as strong as the EN of the century in 1997/98, with extreme heat and drought over most of Amazonian rainforests. Here we show that this protracted EN event, combined with the regional warming trend, was associated with unprecedented warming and a larger extent of extreme drought in Amazonia compared to the earlier strong EN events in 1982/83 and 1997/98. Typical EN-like drought conditions were observed only in eastern Amazonia, whilst in western Amazonia there was an unusual wetting. We attribute this wet-dry dipole to the location of the maximum sea surface warming on the Central equatorial Pacific. The impacts of this climate extreme on the rainforest ecosystems remain to be documented and are likely to be different to previous strong EN events. PMID:27604976

  12. Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015–2016

    NASA Astrophysics Data System (ADS)

    Jiménez-Muñoz, Juan C.; Mattar, Cristian; Barichivich, Jonathan; Santamaría-Artigas, Andrés; Takahashi, Ken; Malhi, Yadvinder; Sobrino, José A.; Schrier, Gerard Van Der

    2016-09-01

    The El Niño-Southern Oscillation (ENSO) is the main driver of interannual climate extremes in Amazonia and other tropical regions. The current 2015/2016 EN event was expected to be as strong as the EN of the century in 1997/98, with extreme heat and drought over most of Amazonian rainforests. Here we show that this protracted EN event, combined with the regional warming trend, was associated with unprecedented warming and a larger extent of extreme drought in Amazonia compared to the earlier strong EN events in 1982/83 and 1997/98. Typical EN-like drought conditions were observed only in eastern Amazonia, whilst in western Amazonia there was an unusual wetting. We attribute this wet-dry dipole to the location of the maximum sea surface warming on the Central equatorial Pacific. The impacts of this climate extreme on the rainforest ecosystems remain to be documented and are likely to be different to previous strong EN events.

  13. Warmed winters and weakened precipitation on Mt. Everest (central southern Himalaya) impacts glaciers, lakes, permafrost, and river discharges

    NASA Astrophysics Data System (ADS)

    Salerno, F.; Guyennon, N.; Thakuri, S.; Freppaz, M.; Balestrini, R.; Vuillermoz, E.; Tartari, G.

    2014-12-01

    This contribution aims linking temperature and precipitation patterns detected at high elevation of south slopes of Mt. Everest with a) glacier and lake surfaces, b) altitude limit of permafrost, c) frequency of daily river discharges. The study is carried out though: a) the daily temperature and precipitation reconstruction of the last twenty years (1994-2013) at 5050 m a.s.l. and 25 AWSs located at lower elevation and on Tibetan Plateau b) glacier surfaces (about 400 km2) and lake areas (more than 100 lakes) since 60s using all available satellite imagery c) permafrost distribution carried out with soil temperature measurements (2010-2012) compared with previous studies (70s) d) the results of a stochastic frequency model (wavelet analysis) for detecting river discharge changes in frequency of the Dud Koshi River basin (3000 km2) since 60s. We observed an increasing temperature trend occurred mainly in winter months, but during the summer ones we observed a slight decreasing of maximum temperature. We confirm for these high elevations the generalized weakening of the monsoon already observed in literature accounting here over 50% of reduction in the last 20 years! In the previous period (70s to 90s) gridded an reanalysis data revealed for our reference site a slighter increase of mean temperature and weak increase of precipitation. Main climate change driven implications: - The accelerated shrinkage of glaciers observed in the last twenty years, usually inferred to the temperature increase during the summer months, is ascribed here mainly to the regional monsoon weakening. - Supraglacial lakes confirm the acceleration of the negative mass balance of glaciers due to reduced ice velocities caused by decreased precipitation. - Unconnected lakes confirms precisely the observed precipitation trend. - The altitudinal limit of the permanent permafrost seems to be unchanged since the beginning '90s (probably due to stationary summer temperature). - Rivers discharges

  14. Midlatitude Winter Storms Propagating into the United States: Diagnosing the Moisture Sources for Extreme Precipitation Events in the Intermountain West

    NASA Astrophysics Data System (ADS)

    Alexander, M. A.; Scott, J.; Swales, D. J.; Hughes, M.; Barsugli, J. J.; Mahoney, K. M.

    2013-12-01

    It is not obvious how the large volume of water necessary to sustain intense precipitation events in the intermountain west reach their destination given the distance from the moisture source in the Pacific and the complex topography that impedes the flow of moisture to that region. Since flow over mountain causes air to cool and thus hold less moisture, air parcels may take unique pathways and/or have multiple moisture sources, to retain enough water to have intense precipitation events in states such as Arizona, Colorado, Idaho and Utah. In general, it would be useful to both scientists and water mangers, to better understand the synoptic and climatic processes that influence heavy precipitation events in the US intermountain west. Atmospheric rivers (ARs), long narrow bands of enhanced water vapor transport, are the dominant mechanism for generating intense precipitation events along the west coast of the US during winter. While studies over the past 10 years have extensively explored the impact of atmospheric rivers on the temperature and precipitation west of the Sierra Nevada and Cascade mountains, their influence on the weather in the intermountain west remains an open question. For example, does much of the moisture transport occur through narrow gaps in the mountains or can it remain in the atmosphere after passing over higher topography? What synoptic features are important for heavy precipitation to occur? We investigate extreme precipitation events and their relation to atmospheric rivers in the US intermountain west (taken here to be between the Sierra Nevada/Cascade Mountains and the Continental Divide). We employ empirical orthogonal function (EOFs) of integrated water vapor transport (IVT), air-parcel trajectory analysis, and time-averaged climate diagnostics to determine the moisture pathways and the broader set of processes that result in these intense precipitation events. These analyses will be performed using Climate Forecast System Reanalysis

  15. Quantitative and qualitative responses of soil organic carbon to six years of extreme soil warming in a subarctic grassland in Iceland

    NASA Astrophysics Data System (ADS)

    Poeplau, Christopher; Leblans, Niki I. W.; Sigurdsson, Bjarni D.; Kätterer, Thomas

    2016-04-01

    Terrestrial carbon cycle feedbacks to global warming are expected, but constitute a major uncertainty in climate models. Soils in northern latitudes store a large proportion of the total global biosphere carbon stock and might thus become a strong source of CO2 when warmed. Long-term in situ observations of warming effects on soil organic carbon (SOC) dynamics are indispensable for an in depth understanding of the involved processes. We investigated the effect of six years of soil warming on SOC quantity and quality in a geothermally heated grassland soil in Iceland. We isolated five fractions of SOC along an extreme soil warming gradient of +0 to +40°C. Those fractions vary conceptually in turnover time from active to passive in the following order: particulate organic matter (POM), dissolved organic carbon (DOC), SOC in sand and stable aggregates (SA), SOC in silt and clay (SC-rSOC) and resistant SOC (rSOC). Soil warming of 1°C increased bulk SOC by 22% (0-10 cm) and 27% (20-30 cm), while further warming led to exponential SOC depletion of up to 79% (0-10 cm) and 74% (20-30) in the most heated plots (~ +40°C). Only the SA fraction was more sensitive than the bulk soil, with 93% (0-10 cm) and 86% (20-30 cm) losses and with the highest relative enrichment in 13C (+1.6‰ in 0-10 cm and +1.3‰ in 20-30 cm). In addition, the mass of the SA fraction did significantly decline along the warming gradient, which we explained by devitalization of aggregate binding mechanisms. As a consequence, the fine SC fraction mass increased with warming which explained the relative enrichment of presumably more slow-cycling SOC (R2=0.61 in 0-10 cm and R2=0.92 in 20-30 cm). Unexpectedly, no difference was observed between the responses of SC-rSOC (slow-cycling) and rSOC (passive) to warming. Furthermore, the 13C enrichment by trophic fractionation in the passive rSOC fraction was equal to this in the bulk soil. We therefore conclude that the sensitivity of SOC to warming was not a

  16. Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

    PubMed

    Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

    2012-05-01

    Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season.

  17. Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

    PubMed

    Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

    2012-05-01

    Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. PMID:21839679

  18. Is "Warm Arctic, Cold Continent" A Fingerprint Pattern of Climate Change?

    NASA Astrophysics Data System (ADS)

    Hoerling, M. P.; Sun, L.; Perlwitz, J.

    2015-12-01

    Cold winters and cold waves have recently occurred in Europe, central Asia and the Midwest to eastern United States, even as global mean temperatures set record highs and Arctic amplification of surface warming continued. Since 1979, Central Asia winter temperatures have in fact declined. Conjecture has it that more cold extremes over the mid-latitude continents should occur due to global warming and the impacts of Arctic sea ice loss. A Northern Hemisphere temperature signal termed the "Warm Arctic, Cold Continent" pattern has thus been surmised. Here we use a multi-model approach to test the hypothesis that such a pattern is indeed symptomatic of climate change. Diagnosis of a large model ensemble of historical climate simulations shows some individual realizations to yield cooling trends over Central Asia, but importantly the vast majority show warming. The observed cooling has thus likely been a low probability state of internal variability, not a fingerprint of forced climate change. We show that daily temperature variations over continents decline in winter due to global warming, and cold waves become less likely. This is partly related to diminution of Arctic cold air reservoirs due to warming-induced sea ice loss. Nonetheless, we find some evidence and present a physical basis that Arctic sea ice loss alone can induce a winter cooling over Central Asia, though with a magnitude that is appreciably smaller than the overall radiative-forced warming signal. Our results support the argument that recent cooling trends over central Asia, and cold extreme events over the winter continents, have principally resulted from atmospheric internal variability and have been neither a forced response to Arctic seas ice loss nor a symptom of global warming. The paradigm of climate change is thus better expressed as "Warm Arctic, Warm Continent" for the NH winter.

  19. Grain Yield and Water Use Efficiency in Extremely-Late Sown Winter Wheat Cultivars under Two Irrigation Regimes in the North China Plain

    PubMed Central

    Wang, Bin; Zhang, Yinghua; Hao, Baozhen; Xu, Xuexin; Zhao, Zhigan; Wang, Zhimin; Xue, Qingwu

    2016-01-01

    Wheat production is threatened by water shortages and groundwater over-draft in the North China Plain (NCP). In recent years, winter wheat has been increasingly sown extremely late in early to mid-November after harvesting cotton or pepper. To improve water use efficiency (WUE) and guide the extremely late sowing practices, a 3-year field experiment was conducted under two irrigation regimes (W1, one-irrigation, 75 mm at jointing; W2, two-irrigation, 75 mm at jointing and 75 mm at anthesis) in 3 cultivars differing in spike size (HS4399, small spike; JM22, medium spike; WM8, large spike). Wheat was sown in early to mid-November at a high seeding rate of 800–850 seeds m−2. Average yields of 7.42 t ha−1 and WUE of 1.84 kg m−3 were achieved with an average seasonal evapotranspiration (ET) of 404 mm. Compared with W2, wheat under W1 did not have yield penalty in 2 of 3 years, and had 7.9% lower seasonal ET and 7.5% higher WUE. The higher WUE and stable yield under W1 was associated with higher 1000-grain weight (TGW) and harvest index (HI). Among the 3 cultivars, JM22 had 5.9%–8.9% higher yield and 4.2%–9.3% higher WUE than WM8 and HS4399. The higher yield in JM22 was attributed mainly to higher HI and TGW due to increased post-anthesis biomass and deeper seasonal soil water extraction. In conclusion, one-irrigation with a medium-sized spike cultivar JM22 could be a useful strategy to maintain yield and high WUE in extremely late-sown winter wheat at a high seeding rate in the NCP. PMID:27100187

  20. Extreme Winter Precipitation Events in the Western United States: The impact of ENSO and the Madden-Julian Oscillation

    NASA Astrophysics Data System (ADS)

    Schubert, S.; Chang, Y.; Suarez, M.; Pegion, P.

    2005-05-01

    The west coast of the United States occasionally experiences intense winter storms that account for a major fraction of the total seasonal rain(snow)fall. In some cases, it is not a single storm, but a series of storms, that batter the west coast in a matter of few weeks. These storms, unfortunately, are often associated with flooding, mudslides and other disasters that can lead to extensive property damage and even loss of life. In this talk, I will review our current understanding of the nature of these storms and the extent to which their occurrence is impacted by El Nino/Southern Oscillation and the Madden Julian Oscillation. The results are based on 50 years of precipitation observations, NCEP/NCAR reanalyses, and idealized experiments with a global atmospheric general circulation model.

  1. Extreme defoliation reduces tree growth but not C and N storage in a winter-deciduous species

    PubMed Central

    Piper, Frida I.; Gundale, Michael J.; Fajardo, Alex

    2015-01-01

    Background and Aims There is a growing concern about how forests will respond to increased herbivory associated with climate change. Carbon (C) and nitrogen (N) limitation are hypothesized to cause decreasing growth after defoliation, and eventually mortality. This study examines the effects of a natural and massive defoliation by an insect on mature trees’ C and N storage, which have rarely been studied together, particularly in winter-deciduous species. Methods Survival, growth rate, carbon [C, as non-structural carbohydrate (NSC) concentration] and nitrogen (N) storage, defences (tannins and total polyphenols), and re-foliation traits were examined in naturally defoliated and non-defoliated adult trees of the winter-deciduous temperate species Nothofagus pumilio 1 and 2 years after a massive and complete defoliation caused by the caterpillar of Ormiscodes amphimone (Saturniidae) during summer 2009 in Patagonia. Key Results Defoliated trees did not die but grew significantly less than non-defoliated trees for at least 2 years after defoliation. One year after defoliation, defoliated trees had similar NSC and N concentrations in woody tissues, higher polyphenol concentrations and lower re-foliation than non-defoliated trees. In the second year, however, NSC concentrations in branches were significantly higher in defoliated trees while differences in polyphenols and re-foliation disappeared and decreased, respectively. Conclusions The significant reduction in growth following defoliation was not caused by insufficient C or N availability, as frequently assumed; instead, it was probably due to growth limitations due to factors other than C or N, or to preventative C allocation to storage. This study shows an integrative approach to evaluating plant growth limitations in response to disturbance, by examining major resources other than C (e.g. N), and other C sinks besides storage and growth (e.g. defences and re-foliation). PMID:25851136

  2. How Were Southwest Pacific Pelagic Ecosystems Affected by Extreme Global Warming During the Initial Eocene Thermal Maximum?

    NASA Astrophysics Data System (ADS)

    Hollis, C. J.; Crouch, E. M.; Dickens, G. R.

    2004-12-01

    Four sections in eastern New Zealand provide the only South Pacific record of the initial Eocene thermal maximum (IETM): a siliciclastic outer shelf section (Tawanui, Hawkes Bay) and three pelagic-hemipelagic sections forming an outer shelf-upper slope transect across a carbonate ramp (Muzzle, Dee and Mead Streams, Clarence Valley). Although the rocks are too indurated to yield reliable oxygen isotope data, the IETM is identified by bulk carbonate carbon isotopes as a sharp negative excursion followed by gradual recovery over 0.6 to 4.0 m. In all sections, the excursion is mirrored by terrigenous sediment concentration, due to reduced biogenic (carbonate and silica) input and increased terrigenous input. Increased precipitation under warm humid conditions appears to have increased terrestrial discharge, recorded by deposition of smectitic marl in pelagic settings and illite/kaolinite-bearing smectitic mudstone in neritic settings. Eutrophic conditions are inferred for the IETM interval at Tawanui based on dysoxia, carbonate dissolution, an acme for the peridinioid dinocyst Apectodinium and abundant Toweius spp in nannofossil assemblages. Continued abundance of Toweius and replacement of Apectodinium by peridinioids of the Deflandrea complex suggests that eutrophic, albeit cooler, conditions persisted for at least 0.5 Ma after the IETM. In contrast, the IETM in Clarence Valley is marked by reduced biogenic silica content but little change in carbonate, and no evidence for carbonate dissolution. Sparse, poorly preserved palynomorphs assemblages suggest organic matter was oxidised under fully oxic conditions. Reduced numbers of upwelling indicators in the siliceous microfossil assemblage and common warm-water planktic foraminifera (Morozovella spp.), nannoplankton (Discoaster spp.) and radiolarians (e.g. Podocyrtis and Theocorys spp.) signal a switch from eutrophic to oligotrophic conditions and significant warming of near-surface waters. A progressive increase in

  3. Hydrological consequences of global warming

    SciTech Connect

    Miller, Norman L.

    2009-06-01

    The 2007 Intergovernmental Panel for Climate Change indicates there is strong evidence that the atmospheric concentration of carbon dioxide far exceeds the natural range over the last 650,000 years, and this recent warming of the climate system is unequivocal, resulting in more frequent extreme precipitation events, earlier snowmelt runoff, increased winter flood likelihoods, increased and widespread melting of snow and ice, longer and more widespread droughts, and rising sea level. The effects of recent warming has been well documented and climate model projections indicate a range of hydrological impacts with likely to very likely probabilities (67 to 99 percent) of occurring with significant to severe consequences in response to a warmer lower atmosphere with an accelerating hydrologic cycle.

  4. Factors affecting the distribution of mallards wintering in the Mississippi alluvial valley

    USGS Publications Warehouse

    Nichols, J.D.; Reinecke, K.J.; Hines, J.E.

    1983-01-01

    The Mississippi Alluvial Valley (MAV) is the principal wintering area for mallards (Anas platyrhynchos ) in the Mississippi Flyway. Here the authors consider it a distinct habitat, i.e., fitness is relatively homogeneous among ducks within the MAV but different from that of ducks in other such habitats. They analyzed recovery distributions of mallards banded preseason (July-September 1950-1980) to test hypotheses concerning the effects of winter temperatures, precipitation, and population levels on mallard winter distribution. When two groups of years that comprised extremes of warm and cold winter weather were compared, recovery distributions of all four age and sex classes (adult males and females, young males and females) differed significantly; recoveries were located farther south in cold years. The authors concluded that temperature, water conditions, and population size affect the habitat suitability of mallard wintering areas and that mallards exhibit considerable flexibility in winter distribution associated with these factors.

  5. Climatic and biotic extreme events moderate long-term responses of above- and belowground sub-Arctic heathland communities to climate change.

    PubMed

    Bokhorst, Stef; Phoenix, Gareth K; Berg, Matty P; Callaghan, Terry V; Kirby-Lambert, Christopher; Bjerke, Jarle W

    2015-11-01

    Climate change impacts are not uniform across the Arctic region because interacting factors causes large variations in local ecosystem change. Extreme climatic events and population cycles of herbivores occur simultaneously against a background of gradual climate warming trends and can redirect ecosystem change along routes that are difficult to predict. Here, we present the results from sub-Arctic heath vegetation and its belowground micro-arthropod community in response to the two main drivers of vegetation damage in this region: extreme winter warming events and subsequent outbreaks of the defoliating autumnal moth caterpillar (Epirrita autumnata). Evergreen dwarf shrub biomass decreased (30%) following extreme winter warming events and again by moth caterpillar grazing. Deciduous shrubs that were previously exposed to an extreme winter warming event were not affected by the moth caterpillar grazing, while those that were not exposed to warming events (control plots) showed reduced (23%) biomass from grazing. Cryptogam cover increased irrespective of grazing or winter warming events. Micro-arthropods declined (46%) following winter warming but did not respond to changes in plant community. Extreme winter warming and caterpillar grazing suppressed the CO2 fluxes of the ecosystem. Evergreen dwarf shrubs are disadvantaged in a future sub-Arctic with more stochastic climatic and biotic events. Given that summer warming may further benefit deciduous over evergreen shrubs, event and trend climate change may both act against evergreen shrubs and the ecosystem functions they provide. This is of particular concern given that Arctic heath vegetation is typically dominated by evergreen shrubs. Other components of the vegetation showed variable responses to abiotic and biotic events, and their interaction indicates that sub-Arctic vegetation response to multiple pressures is not easy to predict from single-factor responses. Therefore, while biotic and climatic events may

  6. Climatic and biotic extreme events moderate long-term responses of above- and belowground sub-Arctic heathland communities to climate change.

    PubMed

    Bokhorst, Stef; Phoenix, Gareth K; Berg, Matty P; Callaghan, Terry V; Kirby-Lambert, Christopher; Bjerke, Jarle W

    2015-11-01

    Climate change impacts are not uniform across the Arctic region because interacting factors causes large variations in local ecosystem change. Extreme climatic events and population cycles of herbivores occur simultaneously against a background of gradual climate warming trends and can redirect ecosystem change along routes that are difficult to predict. Here, we present the results from sub-Arctic heath vegetation and its belowground micro-arthropod community in response to the two main drivers of vegetation damage in this region: extreme winter warming events and subsequent outbreaks of the defoliating autumnal moth caterpillar (Epirrita autumnata). Evergreen dwarf shrub biomass decreased (30%) following extreme winter warming events and again by moth caterpillar grazing. Deciduous shrubs that were previously exposed to an extreme winter warming event were not affected by the moth caterpillar grazing, while those that were not exposed to warming events (control plots) showed reduced (23%) biomass from grazing. Cryptogam cover increased irrespective of grazing or winter warming events. Micro-arthropods declined (46%) following winter warming but did not respond to changes in plant community. Extreme winter warming and caterpillar grazing suppressed the CO2 fluxes of the ecosystem. Evergreen dwarf shrubs are disadvantaged in a future sub-Arctic with more stochastic climatic and biotic events. Given that summer warming may further benefit deciduous over evergreen shrubs, event and trend climate change may both act against evergreen shrubs and the ecosystem functions they provide. This is of particular concern given that Arctic heath vegetation is typically dominated by evergreen shrubs. Other components of the vegetation showed variable responses to abiotic and biotic events, and their interaction indicates that sub-Arctic vegetation response to multiple pressures is not easy to predict from single-factor responses. Therefore, while biotic and climatic events may

  7. Behavior of zonal mean aerosol extinction ratio and its relationship with zonal mean temperature during the winter 1978-1979 stratospheric warming

    NASA Technical Reports Server (NTRS)

    Wang, P.-H.; Mccormick, M. P.

    1985-01-01

    The behavior of the zonal mean aerosol extinction ratio in the lower stratosphere near 75 deg N and its relationship with the zonal mean temperature during the January-February 1979 stratospheric sudden warming have been investigated based on the satellite sensor SAM II (Stratospheric Aerosol Measurement) and auxiliary meteorological measurements. The results indicate that distinct changes in the zonal mean aerosol extinction ratio occurred during this stratospheric sudden warming. It is also found that horizontal eddy transport due to planetary waves may have played a significant role in determining the distribution of the zonal mean aerosol extinction ratio.

  8. Holocene winter climate variability in mid-latitude western North America.

    PubMed

    Ersek, Vasile; Clark, Peter U; Mix, Alan C; Cheng, Hai; Edwards, R Lawrence

    2012-01-01

    Water resources in western North America depend on winter precipitation, yet our knowledge of its sensitivity to climate change remains limited. Similarly, understanding the potential for future loss of winter snow pack requires a longer perspective on natural climate variability. Here we use stable isotopes from a speleothem in southwestern Oregon to reconstruct winter climate change for much of the past 13,000 years. We find that on millennial time scales there were abrupt transitions between warm-dry and cold-wet regimes. Temperature and precipitation changes on multi-decadal to century timescales are consistent with ocean-atmosphere interactions that arise from mechanisms similar to the Pacific Decadal Oscillation. Extreme cold-wet and warm-dry events that punctuated the Holocene appear to be sensitive to solar forcing, possibly through the influence of the equatorial Pacific on the winter storm tracks reaching the US Pacific Northwest region. PMID:23187619

  9. Fossil vs. non-fossil sources of fine carbonaceous aerosols in four Chinese cities during the extreme winter haze episode of 2013

    NASA Astrophysics Data System (ADS)

    Zhang, Y.-L.; Huang, R.-J.; El Haddad, I.; Ho, K.-F.; Cao, J.-J.; Han, Y.; Zotter, P.; Bozzetti, C.; Daellenbach, K. R.; Canonaco, F.; Slowik, J. G.; Salazar, G.; Schwikowski, M.; Schnelle-Kreis, J.; Abbaszade, G.; Zimmermann, R.; Baltensperger, U.; Prévôt, A. S. H.; Szidat, S.

    2015-02-01

    During winter 2013, extremely high concentrations (i.e., 4-20 times higher than the World Health Organization guideline) of PM2.5 (particulate matter with an aerodynamic diameter < 2.5 μm) mass concentrations (24 h samples) were found in four major cities in China including Xi'an, Beijing, Shanghai and Guangzhou. Statistical analysis of a combined data set from elemental carbon (EC), organic carbon (OC), 14C and biomass-burning marker measurements using Latin hypercube sampling allowed a quantitative source apportionment of carbonaceous aerosols. Based on 14C measurements of EC fractions (six samples each city), we found that fossil emissions from coal combustion and vehicle exhaust dominated EC with a mean contribution of 75 ± 8% across all sites. The remaining 25 ± 8% was exclusively attributed to biomass combustion, consistent with the measurements of biomass-burning markers such as anhydrosugars (levoglucosan and mannosan) and water-soluble potassium (K+). With a combination of the levoglucosan-to-mannosan and levoglucosan-to-K+ ratios, the major source of biomass burning in winter in China is suggested to be combustion of crop residues. The contribution of fossil sources to OC was highest in Beijing (58 ± 5%) and decreased from Shanghai (49 ± 2%) to Xi'an (38 ± 3%) and Guangzhou (35 ± 7%). Generally, a larger fraction of fossil OC was from secondary origins than primary sources for all sites. Non-fossil sources accounted on average for 55 ± 10 and 48 ± 9% of OC and total carbon (TC), respectively, which suggests that non-fossil emissions were very important contributors of urban carbonaceous aerosols in China. The primary biomass-burning emissions accounted for 40 ± 8, 48 ± 18, 53 ± 4 and 65 ± 26% of non-fossil OC for Xi'an, Beijing, Shanghai and Guangzhou, respectively. Other non-fossil sources excluding primary biomass burning were mainly attributed to formation of secondary organic carbon (SOC) from non-fossil precursors such as biomass

  10. Causes of the northern high-latitude land surface winter climate change

    NASA Astrophysics Data System (ADS)

    Liu, Jiping; Curry, Judith A.; Dai, Yongjiu; Horton, Radley

    2007-07-01

    In the past two decades, the northern high-latitude (>40°N, NHL) land surface winter climate has experienced some of the most rapid changes on Earth, warming at almost 2.5 times the global average warming. Here we examine impacts of two dominant climate modes - Arctic Oscillation (AO) and Aleutian Low (AL) - on the winter NHL land surface temperature for the period 1958-2004, showing that 1) a combination of the AO and AL explains 70% of the variance of the NHL land surface temperature variability, including the cooling during the 1960s and 1970s and the persistent warming thereafter; and 2) interactions between the AO and AL tend to constrain impacts of the extremes of the AO and AL and minimize spatiotemporal extremes in the NHL climate. The amplification of the winter NHL land surface warming relative to the global average warming can be attributed to the combination of the AO and AL, although the extent to which the greenhouse warming may influence the AO and AL is uncertain.

  11. Winter Storms and Extreme Cold

    MedlinePlus

    ... and weight. Heavier oils congeal more at low temperatures and do not lubricate as well. Thermostat - ensure ... and become slippery. Wind Chill - Windchill is the temperature it “feels like” when you are outside. The ...

  12. Impact of multi-decadal scale changes in large-scale circulation in the North Atlantic sector on Mediterranean winter extreme hydroclimate.

    NASA Astrophysics Data System (ADS)

    Barcikowska, Monika; Kapnick, Sarah

    2016-04-01

    The Mediterranean region, located in the transition zone between the dry subtropical and wet European climate, is very sensitive to changes in the global mean climate state. Those changes, either radiatively forced or caused by intrinsic climate variability, may have a large impact on the presently observed and future hydroclimate in the region. Observations are usually insufficiently long to investigate and attribute decadal-scale hydroclimate changes. On the other hand, models still struggle to correctly reproduce the main mechanisms controlling Mediterranean hydroclimate and have resolutions that are too coarse to realistically simulate extreme hydroclimatic phenomena. In this study we employ two simulations: GFDL CM2.1 and CM2.5. GFDL CM2.5 has higher spatial and temporal resolution, and has been shown to provide a reliable representation of large-scale circulation and its impact on the Mediterranean hydroclimate. This representation is consistent with observations, to the extent that observations are available. Multi-channel singular spectrum analysis (MSSA) was applied to isolate spatio-temporal patterns of two components, which dominate the coupled ocean-atmosphere multidecadal variability over the Northern Atlantic and a large part of Europe. These components resemble the observed North Atlantic Oscillation and Eastern Atlantic Pattern (Hurrel 1999, Hurrel 2003). Both modulate the winter mean state atmospheric flow over the North Atlantic and European regions in their own unique way, which impacts precipitation over North Africa, the Mediterranean Sea and southern Europe on decadal time scales. These results provide a necessary foundation for the second part of the study, where we quantify the influence of anthropogenic forcing on large-scale atmospheric circulation and associated Mediterranean hydroclimate.

  13. Spatial and temporal variation in daily temperature indices in summer and winter seasons over India (1969-2012)

    NASA Astrophysics Data System (ADS)

    Kumar, Naresh; Jaswal, A. K.; Mohapatra, M.; Kore, P. A.

    2016-06-01

    Spatial and temporal variations in summer and winter extreme temperature indices are studied by using daily maximum and minimum temperatures data from 227 surface meteorological stations well distributed over India for the period 1969-2012. For this purpose, time series for six extreme temperature indices namely, hot days (HD), very hot days (VHD), extremely hot days (EHD), cold nights (CN), very cold nights (VCN), and extremely cold nights (ECN) are calculated for all the stations. In addition, time series for mean extreme temperature indices of summer and winter seasons are also analyzed. Study reveals high variability in spatial distribution of threshold temperatures of extreme temperature indices over the country. In general, increasing trends are observed in summer hot days indices and decreasing trends in winter cold night indices over most parts of the country. The results obtained in this study indicate warming in summer maximum and winter minimum temperatures over India. Averaged over India, trends in summer hot days indices HD, VHD, and EHD are significantly increasing (+1.0, +0.64, and +0.32 days/decade, respectively) and winter cold night indices CN, VCN, and ECN are significantly decreasing (-0.93, -0.47, and -0.15 days/decade, respectively). Also, it is observed that the impact of extreme temperature is higher along the west coast for summer and east coast for winter.

  14. Winter Survival: A Consumer's Guide to Winter Preparedness.

    ERIC Educational Resources Information Center

    Department of Energy, Washington, DC.

    This booklet discusses a variety of topics to help consumers prepare for winter. Tips for the home include: winterizing the home, dealing with a loss of heat or power failure, and what you need to have on hand. Another section gives driving tips and what to do in a storm. Health factors include suggestions for keeping warm, signs and treatment for…

  15. Synoptic conditions during wintertime temperature extremes in Alaska

    NASA Astrophysics Data System (ADS)

    Cassano, John J.; Cassano, Elizabeth N.; Seefeldt, Mark W.; Gutowski, William J.; Glisan, Justin M.

    2016-04-01

    The large-scale atmospheric state associated with widespread wintertime warm and cold extremes in southern Alaska was identified using 1989 to 2007 European Centre for Medium-Range Weather Forecasts Interim Re-Analysis (ERA-I) data. Extremes were defined as days with the coldest and warmest 1% of daily temperatures. Widespread extreme events were identified for days when at least 25 50 km grid cells in the study domain met the extreme temperature criteria. A total of 55 cold and 74 warm extreme days were identified in 19 winters. Composites of the atmospheric state from 5 days before through the day of the extreme events were analyzed to assess the large-scale atmospheric state associated with the extremes. The method of self-organizing maps (SOMs) was used to identify the range of sea level pressure (SLP) patterns present in the ERA-I December-February data, and these SLP patterns were then used to stratify the extreme days by their large-scale atmospheric circulation. Composites for all warm or cold extreme days showed less intense features than those for specific SLP patterns. In all of the composites temperature advection, strongest at 700 hPa, and anomalous longwave radiation were the primary factors that led to the extreme events. The anomalous downwelling longwave radiation was due to either reduced cloud cover, during cold extremes, or to increased cloud cover, during warm extremes. The SOM composites provided additional insight into the temporal evolution of the extreme days and highlighted different portions of southern Alaska most likely to experience temperature extremes for a given SOM SLP pattern.

  16. Short winters threaten temperate fish populations

    PubMed Central

    Farmer, Troy M.; Marschall, Elizabeth A.; Dabrowski, Konrad; Ludsin, Stuart A.

    2015-01-01

    Although climate warming is expected to benefit temperate ectotherms by lengthening the summer growing season, declines in reproductive success following short, warm winters may counter such positive effects. Here we present long-term (1973–2010) field patterns for Lake Erie yellow perch, Perca flavescens, which show that failed annual recruitment events followed short, warm winters. Subsequent laboratory experimentation and field investigations revealed how reduced reproductive success following short, warm winters underlie these observed field patterns. Following short winters, females spawn at warmer temperatures and produce smaller eggs that both hatch at lower rates and produce smaller larvae than females exposed to long winters. Our research suggests that continued climate warming can lead to unanticipated, negative effects on temperate fish populations. PMID:26173734

  17. On-Going Temperature Extremes in Siberia

    NASA Astrophysics Data System (ADS)

    Shulgina, T. M.; Gordov, E. P.

    2014-12-01

    Ongoing global climate changes accompanied by the restructuring of global processes in the atmosphere and biosphere are strongly pronounced in the Northern Eurasia regions, especially in Siberia. Temperature trends (grows up to 0.5 °C per decade), more frequent occurrence of temperature extremes provoked serious natural disasters (2010 heat waves in Russia, 2013 flood in Russia's Far East) led to socio-economical impact (crop damages, infrastructure failures, respectively). To get reliable knowledge on location, frequency and magnitude of observed extremes we have studied daily max/min temperature trends based on ECMWF ERA Interim Reanalysis data (0,25°×0,25°). This dataset is most accurately reproduces observed temperature behavior in the region. Statistical analysis of daily temperature time series (1979-2012) indicates the asymmetric changes in distribution tails of such extreme indices as warm/cold days/nights. Namely, the warming during winter cold nights is stronger than during warm nights, especially over the north of Siberia. Increases in minimum temperatures are more significant than in maximum temperatures. Warming determined at the high latitudes of the region is achieved mostly due to winter temperature changes. South area of Siberia has slightly cooling during winter and summer. Results obtained provide regional decision-makers with detailed high spatial and temporal resolution climatic information required for adaptation and mitigation measures development. Calculations presented have been realized using information-computational web-GIS system "Climate" (http://climate.scert.ru/) which automatically generates the archive of calculated fields ready for multidisciplinary studies of regional climate change impacts. The authors acknowledge partial financial support for this research from the RFBR (13-05-12034, 14-05-00502), SB RAS 131 and VIII.80.2.1.) and grant of the President of RF (№ 181).

  18. Simulated distributions of Baltic Sea-ice in warming climate and consequences for the winter habitat of the Baltic ringed seal.

    PubMed

    Meier, H E Markus; Döscher, Ralf; Halkka, Antti

    2004-06-01

    Sea-ice in the Baltic Sea in present and future climates is investigated. The Rossby Centre Regional Atmosphere-Ocean model was used to perform a set of 30-year-long time slice experiments. For each of the two driving global models HadAM3H and ECHAM4/OPYC3, one control run (1961-1990) and two scenario runs (2071-2100) based upon the SRES A2 and B2 emission scenarios were conducted. The future sea-ice volume in the Baltic Sea is reduced by 83% on average. The Bothnian Sea, large areas of the Gulf of Finland and Gulf of Riga, and the outer parts of the southwestern archipelago of Finland will become ice-free in the mean. The presented scenarios are used to study the impact of climate change on the Baltic ringed seal (Phoca hispida botnica). Climate change seems to be a major threat to all southern populations. The only fairly good winter sea-ice habitat is found to be confined to the Bay of Bothnia.

  19. Variability of Winter Air Temperature in Mid-Latitude Europe

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Ardizzone, J.; Atlas, R.; Bungato, D.; Cierniewski, J.; Jusem, J. C.; Przybylak, R.; Schubert, S.; Starr, D.; Walczewski, J.

    2002-01-01

    The aim of this paper is to report extreme winter/early-spring air temperature (hereinafter temperature) anomalies in mid-latitude Europe, and to discuss the underlying forcing to these interannual fluctuations. Warm advection from the North Atlantic in late winter controls the surface-air temperature, as indicated by the substantial correlation between the speed of the surface southwesterlies over the eastern North Atlantic (quantified by a specific Index Ina) and the 2-meter level air temperatures (hereinafter Ts) over Europe, 45-60 deg N, in winter. In mid-March and subsequently, the correlation drops drastically (quite often it is negative). This change in the relationship between Ts and Ina marks a transition in the control of the surface-air temperature: absorption of insolation replaces the warm advection as the dominant control. This forcing by maritime-air advection in winter was demonstrated in a previous publication, and is re-examined here in conjunction with extreme fluctuations of temperatures in Europe. We analyze here the interannual variability at its extreme by comparing warm-winter/early-spring of 1989/90 with the opposite scenario in 1995/96. For these two December-to-March periods the differences in the monthly mean temperature in Warsaw and Torun, Poland, range above 10 C. Short-term (shorter than a month) fluctuations of the temperature are likewise very strong. We conduct pentad-by-pentad analysis of the surface-maximum air temperature (hereinafter Tmax), in a selected location, examining the dependence on Ina. The increased cloudiness and higher amounts of total precipitable water, corollary effects to the warm low-level advection. in the 1989/90 winter, enhance the positive temperature anomalies. The analysis of the ocean surface winds is based on the Special Sensor Microwave/Imager (SSM/I) dataset; ascent rates, and over land wind data are from the European Centre for Medium-Range Weather Forecasts (ECMWF); maps of 2-m temperature, cloud

  20. Changes in weather and climate extremes over Korea and possible causes: A review

    NASA Astrophysics Data System (ADS)

    Min, Seung-Ki; Son, Seok-Woo; Seo, Kyong-Hwan; Kug, Jong-Seong; An, Soon-Il; Choi, Yong-Sang; Jeong, Jee-Hoon; Kim, Baek-Min; Kim, Ji-Won; Kim, Yeon-Hee; Lee, June-Yi; Lee, Myong-In

    2015-05-01

    Weather and climate extremes exert devastating influence on human society and ecosystem around the world. Recent observations show increase in frequency and intensity of climate extremes around the world including East Asia. In order to assess current status of the observed changes in weather and climate extremes and discuss possible mechanisms, this study provides an overview of recent analyses on such extremes over Korea and East Asia. It is found that the temperature extremes over the Korean Peninsula exhibit long-term warming trends with more frequent hot events and less frequent cold events, along with sizeable interannual and decadal variabilities. The comprehensive review on the previous literature further suggests that the weather and climate extremes over East Asia can be affected by several climate factors of external and internal origins. It has been assessed that greenhouse warming leads to increase in warm extremes and decrease in cold extremes over East Asia, but recent Arctic sea-ice melting and associated warming tends to bring cold snaps to East Asia during winter. Internal climate variability such as tropical intraseasonal oscillation and El Niño-Southern Oscillation can also exert considerable impacts on weather and climate extremes over Korea and East Asia. It is, however, noted that our current understanding is far behind to estimate the effect of these climate factors on local weather and climate extremes in a quantitative sense.

  1. Weak precipitation, warm winters and springs impact glaciers of south slopes of Mt. Everest (central Himalaya) in the last two decades (1994-2013)

    NASA Astrophysics Data System (ADS)

    Salerno, F.; Guyennon, N.; Thakuri, S.; Viviano, G.; Romano, E.; Vuillermoz, E.; Cristofanelli, P.; Stocchi, P.; Agrillo, G.; Ma, Y.; Tartari, G.

    2014-12-01

    Studies on recent climate trends from the Himalayan range are limited, and even completely absent at high elevation. This contribution specifically explores the southern slopes of Mt. Everest (central Himalaya), analyzing the minimum, maximum, and mean temperature and precipitation time series reconstructed from seven stations located between 2660 and 5600m a.s.l. over the last twenty years (1994-2013). We complete this analysis with data from all the existing ground weather stations located on both sides of the mountain range (Koshi Basin) over the same period. Overall we observe that the main and more significant increase in temperature is concentrated outside of the monsoon period. At higher elevations minimum temperature (0.072 ± 0.011 °C a-1, p < 0.001) increased far more than maximum temperature (0.009 ± 0.012 °C a-1, p > 0.1), while mean temperature increased by 0.044 ± 0.008 °C a-1, p < 0.05. Moreover, we note a substantial precipitation weakening (9.3 ± 1.8mm a-1, p < 0.01 during the monsoon season). The annual rate of decrease at higher elevation is similar to the one at lower altitudes on the southern side of the Koshi Basin, but here the drier conditions of this remote environment make the fractional loss much more consistent (47% during the monsoon period). This study contributes to change the perspective on which climatic driver (temperature vs. precipitation) led mainly the glacier responses in the last twenty years. The main implications are the following: (1) the negative mass balances of glaciers observed in this region can be more ascribed to less accumulation due to weaker precipitation than to an increase of melting processes. (2) The melting processes have only been favored during winter and spring months and close to the glaciers terminus. (3) A decreasing of the probability of snowfall has significantly interested only the glaciers ablation zones (10%, p < 0.05), but the magnitude of this phenomenon is decidedly lower than the

  2. Fourfold higher tundra volatile emissions due to arctic summer warming

    NASA Astrophysics Data System (ADS)

    Lindwall, Frida; Schollert, Michelle; Michelsen, Anders; Blok, Daan; Rinnan, Riikka

    2016-03-01

    Biogenic volatile organic compounds (BVOCs), which are mainly emitted by vegetation, may create either positive or negative climate forcing feedbacks. In the Subarctic, BVOC emissions are highly responsive to temperature, but the effects of climatic warming on BVOC emissions have not been assessed in more extreme arctic ecosystems. The Arctic undergoes rapid climate change, with air temperatures increasing at twice the rate of the global mean. Also, the amount of winter precipitation is projected to increase in large areas of the Arctic, and it is unknown how winter snow depth affects BVOC emissions during summer. Here we examine the responses of BVOC emissions to experimental summer warming and winter snow addition—each treatment alone and in combination—in an arctic heath during two growing seasons. We observed a 280% increase relative to ambient in BVOC emissions in response to a 4°C summer warming. Snow addition had minor effects on growing season BVOC emissions after one winter but decreased BVOC emissions after the second winter. We also examined differences between canopy and air temperatures and found that the tundra canopy surface was on average 7.7°C and maximum 21.6°C warmer than air. This large difference suggests that the tundra surface temperature is an important driver for emissions of BVOCs, which are temperature dependent. Our results demonstrate a strong response of BVOC emissions to increasing temperatures in the Arctic, suggesting that emission rates will increase with climate warming and thereby feed back to regional climate change.

  3. Global warming

    NASA Astrophysics Data System (ADS)

    Houghton, John

    2005-06-01

    'Global warming' is a phrase that refers to the effect on the climate of human activities, in particular the burning of fossil fuels (coal, oil and gas) and large-scale deforestation, which cause emissions to the atmosphere of large amounts of 'greenhouse gases', of which the most important is carbon dioxide. Such gases absorb infrared radiation emitted by the Earth's surface and act as blankets over the surface keeping it warmer than it would otherwise be. Associated with this warming are changes of climate. The basic science of the 'greenhouse effect' that leads to the warming is well understood. More detailed understanding relies on numerical models of the climate that integrate the basic dynamical and physical equations describing the complete climate system. Many of the likely characteristics of the resulting changes in climate (such as more frequent heat waves, increases in rainfall, increase in frequency and intensity of many extreme climate events) can be identified. Substantial uncertainties remain in knowledge of some of the feedbacks within the climate system (that affect the overall magnitude of change) and in much of the detail of likely regional change. Because of its negative impacts on human communities (including for instance substantial sea-level rise) and on ecosystems, global warming is the most important environmental problem the world faces. Adaptation to the inevitable impacts and mitigation to reduce their magnitude are both necessary. International action is being taken by the world's scientific and political communities. Because of the need for urgent action, the greatest challenge is to move rapidly to much increased energy efficiency and to non-fossil-fuel energy sources.

  4. Stratospheric sudden warming and lunar tide

    NASA Astrophysics Data System (ADS)

    Yamazaki, Yosuke; Kosch, Michael

    2016-07-01

    A stratospheric sudden warming is a large-scale disturbance in the middle atmosphere. Recent studies have shown that the effect of stratospheric sudden warnings extends well into the upper atmosphere. A stratospheric sudden warming is often accompanied by an amplification of lunar tides in the ionosphere/theremosphere. However, there are occasionally winters when a stratospheric sudden warming occurs without an enhancement of the lunar tide in the upper atmosphere, and other winters when large lunar tides are observed without a strong stratospheric sudden warming. We examine the winters when the correlation breaks down and discuss possible causes.

  5. Early winter cold spells over the Euro-Mediterranean region

    NASA Astrophysics Data System (ADS)

    Toreti, Andrea; Xoplaki, Elena; Luterbacher, Juerg

    2016-04-01

    In a changing climate context, temperature extremes are expected to heavily impact societies and economies. Projected changes in warm extremes have been extensively investigated, while less efforts are devoted to cold extremes. Despite the projected warming of the climate system, cold extremes could still occur and have an impact on several sectors, such as human health and agriculture. Here, we focus on cold spells that have a potential high impact, i.e. early winter cold spells occurring after a mild-to-warm autumn. Projected changes of these events over the Euro-Mediterranean region are analysed by using the latest Euro-Cordex simulations under the scenarios RCP4.5 and RCP8.5. In terms of spatial extension of cold spells, a significant reduction can be seen only at the end of the 21st century and under the RCP8.5 scenario. As for the changes in intensity in the mid-century, no consistency is found among models over large areas. At the end of the century, the north-eastern part of the domain and northern Africa are projected to be early-cold-spell free under the RCP4.5 scenario, while, almost the entire domain is projected to be early-cold-spell free under the RCP8.5 scenario.

  6. Titan's Emergence from Winter

    NASA Technical Reports Server (NTRS)

    Flasar, F. Michael; Achterberg, Richard; Jennings, Donald; Schinder, Paul

    2011-01-01

    We summarize the changes in Titans thermal structure derived from Cassini CIRS and radio-occultation data during the transition from winter to early spring. Titan's surface, and middle atmosphere show noticeable seasonal change, whereas that in most of the troposphere is mated. This can be understood in terms of the relatively small radiative relaxation time in the middle atmosphere and much larger time scale in the troposphere. The surface exhibits seasonal change because the heat capacity in an annual skin depth is much smaller than that in the lowest scale height of the troposphere. Surface temperatures rise 1 K at raid and high latitudes in the winter northern hemisphere and cool in the southern hemisphere. Changes in in the middle atmosphere are more complicated. Temperatures in the middle stratosphere (approximately 1 mbar) increase by a few kelvin at mid northern latitudes, but those at high latitudes first increase as that region moves out of winter shadow, and then decrease. This probably results from the combined effect of increased solar heating as the suit moves higher in the sky and the decreased adiabatic warming as the sinking motions associated with the cross-equatorial meridional cell weaken. Consistent with this interpretation, the warm temperatures observed higher up at the winter polar stratopause cool significantly.

  7. Delayed flowering and global warming

    NASA Astrophysics Data System (ADS)

    Cook, B. I.; Wolkovich, E. M.; Parmesan, C.

    2011-12-01

    Within general trends toward earlier spring, observed cases of species and ecosystems that have not advanced their phenology, or have even delayed it, appear paradoxical, especially when made in temperate regions experiencing significant warming. The typical interpretation of this pattern has been that non-responders are insensitive to relatively small levels of warming over the past 40 years, while species showing delays are often viewed as statistical noise or evidence for unknown confounding factors at play. However, plant physiology studies suggest that when winter chilling (vernalization) is required to initiate spring development, winter warming may retard spring events, masking expected advances caused by spring warming. Here, we analyzed long-term data on phenology and seasonal temperatures from 490 species on two continents and demonstrate that 1) apparent non-responders are indeed responding to warming, but their responses to winter and spring warming are opposite in sign, 2) observed trends in first flowering date depend strongly on the magnitude of a given species' response to autumn/winter versus spring warming, and 3) inclusion of these effects strongly improves hindcast predictions of long-term flowering trends. With a few notable exceptions, climate change research has focused on the overall mean trend towards phenological advance, minimizing discussion of apparently non-responding species. Our results illuminate an under-studied source of complexity in wild species responses and support the need for models incorporating diverse environmental cues in order to improve predictability of species responses to anthropogenic climate change.

  8. Extremely rapid acclimation of Escherichia coli to high temperature over a few generations of a fed-batch culture during slow warming

    PubMed Central

    Guyot, Stéphane; Pottier, Laurence; Hartmann, Alain; Ragon, Mélanie; Hauck Tiburski, Julia; Molin, Paul; Ferret, Eric; Gervais, Patrick

    2014-01-01

    This study aimed to demonstrate that adequate slow heating rate allows two strains of Escherichia coli rapid acclimation to higher temperature than upper growth and survival limits known to be strain-dependent. A laboratory (K12-TG1) and an environmental (DPD3084) strain of E. coli were subjected to rapid (few seconds) or slow warming (1°C 12 h−1) in order to (re)evaluate upper survival and growth limits. The slow warming was applied from the ancestral temperature 37°C to total cell death 46–54°C: about 30 generations were propagated. Upper survival and growth limits for rapid warming (46°C) were lower than for slow warming (46–54°C). The thermal limit of survival for slow warming was higher for DPD3084 (50–54°C). Further experiments conducted on DPD3084, showed that mechanisms involved in this type of thermotolerance were abolished by a following cooling step to 37°C, which allowed to imply reversible mechanisms as acclimation ones. Acquisition of acclimation mechanisms was related to physical properties of the plasma membrane but was not inhibited by unavoidable appearance of aggregated proteins. In conclusion, E.coli could be rapidly acclimated within few generations over thermal limits described in the literature. Such a study led us to propose that rapid acclimation may give supplementary time to the species to acquire a stable adaptation through a random mutation. PMID:24357618

  9. How Much Winter Stratospheric Polar-cap Warming Is Explained By Upward-propagating Planetary Waves In CMIP5 Models?: Part 1. An Indirect Approach Using A Wave Interference Index

    NASA Astrophysics Data System (ADS)

    Kim, J.; Kim, B.

    2013-12-01

    The breaking of upward-propagating planetary (typically characterized by the combination of zonal wave number 1 and 2) waves in the stratosphere is regarded as one of the factors that provoke the sudden stratospheric warming (SSW) and the accompanying collapse of stratospheric polar vortex during winter. It is also known that if the anomalous stationary wave pattern is in phase with that of the climatology during a certain period, this period is dynamically favorable for the upward propagation and amplification of planetary waves. This kind of phenomenon that amplitude of resultant wave increases by combining two or more waves in phase is called the constructive interference. Our research evaluates whether and to what degree the Coupled Model Intercomparison Project Phase 5 (CMIP5) models simulate such a relation between tropospheric wave interference and Northern polar stratosphere temperature anomaly during winter. Here the 500-hPa wave interference index (WII500) is defined as the coefficient that is obtained by projecting the anomaly of wave number 1 and 2 components of 500-hPa geopotential height onto its climatology. Using monthly outputs of the CMIP5 historical runs currently available to us, we examine the lagged relationship (R-square) between the WII500 during November-December-January (NDJ) and the polar-cap temperature anomaly at 50 hPa (PCT50) during December-January-February (DJF) on an interannual timescale. By sampling uncertainty in R-squares of 33-yr samples (chosen fit with the modern reanalysis period, 1980-2012) with bootstrap resampling, we obtain the sampled medians for all models. The observed relations are then calculated using six reanalyses (ERA-40, ERA-Interim, JRA-25, MERRA, NCEP-R1, and NCEP-R2), and the 5-95% confidence interval of their observed R-square is obtained again with bootstrap resampling of all six reanalyses blended. Then we evaluate which CMIP5 model simulates the WII500-PCT50 relation within the probable range of

  10. Extremes and non-linearities in central England temperatures

    NASA Astrophysics Data System (ADS)

    Palutikof, J. P.; Brabson, B. B.; Holt, T.

    2003-04-01

    It is widely recognized that the impact of climate change on the occurrence of extremes is likely to have greater implications for human societies and the natural environment than any change in the mean. As part of the EU-funded MICE project, we have explored the changing characteristics of extremes over time, taking the example of the central England temperature record. This is a long homogeneous record constructed from between one and four sites, and for daily mean temperatures, extending back to 1772. For the observed record, we use the Generalized Pareto distributions applied to independent exceedances to look at the behaviour of winter and summer extremes in twenty-year overlapping periods. This analysis shows that the cold winter and hot summer extremes have warmed more steeply than their means, and this trend can be related to changes in the atmospheric circulation. For the future, we perform the same analysis over the period up to 2100 for a grid box selected from the HadCM3 GCM (A2 emissions scenario) to be representative of central England. In this case we find that hot summer extremes rise very rapidly compared to the mean, and this can be related to an increase in the length and number of very hot spells in summer (and accompanying reductions in occurrences of very cold winter spells). Finally, a comparison is made of the behaviour of extremes in the HadCM3 experiments forced with the A2 and B2 emissions scenarios.

  11. Warm Hands and Feet

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Comfort Products, Inc. was responsible for the cold weather glove and thermal boots, adapted from a spacesuit design that kept astronauts warm or cool in the temperature extremes of the Apollo Moon Mission. Gloves and boots are thermally heated. Batteries are worn inside wrist of glove or sealed in sole of skiboot and are rechargeable hundreds of times. They operate flexible resistance circuit which is turned on periodically when wearer wants to be warm.

  12. Can Multiple Cropping Help to Avoid the Impacts of Heat Extremes? The Case of Winter Wheat/Soybean Double Cropping in the United States

    NASA Astrophysics Data System (ADS)

    Seifert, C.; Lobell, D. B.

    2014-12-01

    In adapting U.S. agriculture to the climate of the 21st century, multiple cropping presents a unique opportunity to help offset projected negative trends in agricultural production while moving critical crop yield formation periods outside of the hottest months of the year. Critical constraints on this practice include moisture availability, and, more importantly, growing season length. We review evidence that this last constraint has decreased in the previous quarter century, allowing for more winter wheat/soybean double cropping in previously phenologically constrained areas. We also carry this pattern forward to 2100, showing a 126% to 211% increase in the area phenologically suitable for double cropping under the RCP45 and RCP85 scenarios respectively. These results suggest that climate change will relieve phenological constraints on wheat-soy double cropping systems over much of the United States, changing production patterns and crop rotations as areas become suitable for the practice.

  13. The role of convection permitting modeling to evaluate the contribution of the anthropogenic climate change on the UK Winter 2013-2014 extreme rain

    NASA Astrophysics Data System (ADS)

    Omrani, Hiba; Vautard, Robert

    2016-04-01

    During the winter 2013/2014, the UK saw heavy rainfalls associated with a succession of storms reaching Southern England causing widespread flooding, power cuts and major disruptions to transport. The January precipitation set a record for several rain gauge stations in Southern England. The aim of this study is to evaluate the contribution of the anthropogenic climate change, represented by a modification of the sea surface temperature (SST) on the January precipitation. For that, we conducted a sensitivity experiment by running a set of two-months simulations using WRF model with 50km horizontal resolution simulation and 2 km convection permitting simulation centered over the southern UK. We also investigated the sensitivity to the model physics. Results show that the horizontal resolution plays an important role for interpreting the results. Indeed, the low resolution simulation showed no robust signal to attribute this event. However, the convection permitting simulations gave more consistent results over the studied area.

  14. Nutrition for winter sports.

    PubMed

    Meyer, Nanna L; Manore, Melinda M; Helle, Christine

    2011-01-01

    Winter sports are played in cold conditions on ice or snow and often at moderate to high altitude. The most important nutritional challenges for winter sport athletes exposed to environmental extremes include increased energy expenditure, accelerated muscle and liver glycogen utilization, exacerbated fluid loss, and increased iron turnover. Winter sports, however, vary greatly regarding their nutritional requirements due to variable physiological and physique characteristics, energy and substrate demands, and environmental training and competition conditions. What most winter sport athletes have in common is a relatively lean physique and high-intensity training periods, thus they require greater energy and nutrient intakes, along with adequate food and fluid before, during, and after training. Event fuelling is most challenging for cross-country skiers competing in long events, ski jumpers aiming to reduce their body weight, and those winter sport athletes incurring repeated qualification rounds and heats. These athletes need to ensure carbohydrate availability throughout competition. Finally, winter sport athletes may benefit from dietary and sport supplements; however, attention should be paid to safety and efficacy if supplementation is considered.

  15. Winter Weeds.

    ERIC Educational Resources Information Center

    Lindberg, Lois

    1981-01-01

    Try to learn all you can about a plant in the winter. As the season changes, you can see what the dried seed pod is like in bloom. You are a convert if you notice a spectacular show of summer wildflowers and wonder what sort of winter weed will result. (Author/CM)

  16. Isolating Stratospheric Warmings -- Mesosphere to Troposphere

    NASA Astrophysics Data System (ADS)

    Coughlin, K.

    Stratospheric Warming events exhibit the most drastic changes seen in the stratosphere and yet the categorization of these events continues to be adhoc Understandably the definitions of major warming minor warmings and or Canadian warmings often depend on the scientific problem at hand And yet we show here that these events are statistically separated from the rest of the days in the winter stratosphere We show how warmings can be isolated and defined in a objective manner Furthermore we are then able to show the effect of these warmings from the mesosphere down to the troposphere

  17. Nuclear Winter.

    ERIC Educational Resources Information Center

    Ehrlich, Anne

    1984-01-01

    "Nuclear Winter" was recently coined to describe the climatic and biological effects of a nuclear war. These effects are discussed based on models, simulations, scenarios, and projections. Effects on human populations are also considered. (JN)

  18. Global Warming.

    ERIC Educational Resources Information Center

    Hileman, Bette

    1989-01-01

    States the foundations of the theory of global warming. Describes methodologies used to measure the changes in the atmosphere. Discusses steps currently being taken in the United States and the world to slow the warming trend. Recognizes many sources for the warming and the possible effects on the earth. (MVL)

  19. Winter wren populations show adaptation to local climate.

    PubMed

    Morrison, Catriona A; Robinson, Robert A; Pearce-Higgins, James W

    2016-06-01

    Most studies of evolutionary responses to climate change have focused on phenological responses to warming, and provide only weak evidence for evolutionary adaptation. This could be because phenological changes are more weakly linked to fitness than more direct mechanisms of climate change impacts, such as selective mortality during extreme weather events which have immediate fitness consequences for the individuals involved. Studies examining these other mechanisms may be more likely to show evidence for evolutionary adaptation. To test this, we quantify regional population responses of a small resident passerine (winter wren Troglodytes troglodytes) to a measure of winter severity (number of frost days). Annual population growth rate was consistently negatively correlated with this measure, but the point at which different populations achieved stability (λ = 1) varied across regions and was closely correlated with the historic average number of frost days, providing strong evidence for local adaptation. Despite this, regional variation in abundance remained negatively related to the regional mean number of winter frost days, potentially as a result of a time-lag in the rate of evolutionary response to climate change. As expected from Bergmann's rule, individual wrens were heavier in colder regions, suggesting that local adaptation may be mediated through body size. However, there was no evidence for selective mortality of small individuals in cold years, with annual variation in mean body size uncorrelated with the number of winter frost days, so the extent to which local adaptation occurs through changes in body size, or another mechanism remains uncertain. PMID:27429782

  20. Winter wren populations show adaptation to local climate.

    PubMed

    Morrison, Catriona A; Robinson, Robert A; Pearce-Higgins, James W

    2016-06-01

    Most studies of evolutionary responses to climate change have focused on phenological responses to warming, and provide only weak evidence for evolutionary adaptation. This could be because phenological changes are more weakly linked to fitness than more direct mechanisms of climate change impacts, such as selective mortality during extreme weather events which have immediate fitness consequences for the individuals involved. Studies examining these other mechanisms may be more likely to show evidence for evolutionary adaptation. To test this, we quantify regional population responses of a small resident passerine (winter wren Troglodytes troglodytes) to a measure of winter severity (number of frost days). Annual population growth rate was consistently negatively correlated with this measure, but the point at which different populations achieved stability (λ = 1) varied across regions and was closely correlated with the historic average number of frost days, providing strong evidence for local adaptation. Despite this, regional variation in abundance remained negatively related to the regional mean number of winter frost days, potentially as a result of a time-lag in the rate of evolutionary response to climate change. As expected from Bergmann's rule, individual wrens were heavier in colder regions, suggesting that local adaptation may be mediated through body size. However, there was no evidence for selective mortality of small individuals in cold years, with annual variation in mean body size uncorrelated with the number of winter frost days, so the extent to which local adaptation occurs through changes in body size, or another mechanism remains uncertain.

  1. Winter wren populations show adaptation to local climate

    PubMed Central

    Morrison, Catriona A.; Robinson, Robert A.; Pearce-Higgins, James W.

    2016-01-01

    Most studies of evolutionary responses to climate change have focused on phenological responses to warming, and provide only weak evidence for evolutionary adaptation. This could be because phenological changes are more weakly linked to fitness than more direct mechanisms of climate change impacts, such as selective mortality during extreme weather events which have immediate fitness consequences for the individuals involved. Studies examining these other mechanisms may be more likely to show evidence for evolutionary adaptation. To test this, we quantify regional population responses of a small resident passerine (winter wren Troglodytes troglodytes) to a measure of winter severity (number of frost days). Annual population growth rate was consistently negatively correlated with this measure, but the point at which different populations achieved stability (λ = 1) varied across regions and was closely correlated with the historic average number of frost days, providing strong evidence for local adaptation. Despite this, regional variation in abundance remained negatively related to the regional mean number of winter frost days, potentially as a result of a time-lag in the rate of evolutionary response to climate change. As expected from Bergmann's rule, individual wrens were heavier in colder regions, suggesting that local adaptation may be mediated through body size. However, there was no evidence for selective mortality of small individuals in cold years, with annual variation in mean body size uncorrelated with the number of winter frost days, so the extent to which local adaptation occurs through changes in body size, or another mechanism remains uncertain. PMID:27429782

  2. Exceptionally cold and mild winters in Europe (1951-2010)

    NASA Astrophysics Data System (ADS)

    Twardosz, Robert; Kossowska-Cezak, Urszula

    2016-07-01

    Extreme thermal conditions appear to occupy an important place among research subjects at a time of climate warming. This study investigates the frequency, duration and spatial extent of thermally anomalous winters in Europe during the 60 years between 1951 and 2010. Exceptionally cold winters (ECWs) and exceptionally mild winters (EMWs) were identified using the statistical criterion of plus/minus two standard deviations from the long-term winter temperature (January-December) recorded at 60 weather stations. It was demonstrated that ECWs have occurred more frequently and covered larger territories than EMWs and that they may occur anywhere in Europe, while EMWs were limited to its southern and western parts. ECWs are characterised by greater absolute temperature anomalies, as anomalies greater than |6.0 °C| account for 35 % of ECWs, but only for 8 % of EMWs. The greatest anomalies are found in the east of the continent. The largest territory affected by an ECW included 24 stations in 1962/1963, while the equivalent among the EMWs included 11 stations in 2006/2007. The study also confirmed an expected trend whereby ECWs diminished in frequency in favour of EMWs in the second half of the 60-year study period.

  3. Trends in temperature extremes over nine integrated agricultural regions in China, 1961-2011

    NASA Astrophysics Data System (ADS)

    Wu, Xushu; Wang, Zhaoli; Zhou, Xiaowen; Lai, Chengguang; Chen, Xiaohong

    2016-06-01

    By characterizing the patterns of temperature extremes over nine integrated agricultural regions (IARs) in China from 1961 to 2011, this study performed trend analyses on 16 extreme temperature indices using a high-resolution (0.5° × 0.5°) daily gridded dataset and the Mann-Kendall method. The results show that annually, at both daytime and nighttime, cold extremes significantly decreased but warm extremes significantly increased across all IARs. Overall, nighttimes tended to warm faster than daytimes. Diurnal temperature ranges (DTR) diminished, apart from the mid-northern Southwest China Region and the mid-Loess Plateau Region. Seasonally, DTR widely diminished across all IARs during the four seasons except for spring. Higher minimum daily minimum temperature (TNn) and maximum daily maximum temperature (TXx), in both summer and winter, were recorded for most IARs except for the Huang-Huai-Hai Region; in autumn, all IARs generally encountered higher TNn and TXx. In all seasons, warming was observed at daytime and nighttime but, again, nighttimes warmed faster than daytimes. The results also indicate a more rapid warming trend in Northern and Western China than in Southern and Eastern China, with accelerated warming at high elevations. The increases in TNn and TXx might cause a reduction in agriculture yield in spring over Northern China, while such negative impact might occur in Southern China during summer. In autumn and winter, however, the negative impact possibly occurred in most of the IARs. Moreover, increased TXx in the Pearl River Delta and Yangtze River Delta is possibly related to rapid local urbanization. Climatically, the general increase in temperature extremes across Chinese IARs may be induced by strengthened Northern Hemisphere Subtropical High or weakened Northern Hemisphere Polar Vortex.

  4. The seesaw effect of winter temperature change on the recruitment of cotton bollworms Helicoverpa armigera through mismatched phenology.

    PubMed

    Reddy, Gadi V P; Shi, Peijian; Hui, Cang; Cheng, Xiaofei; Ouyang, Fang; Ge, Feng

    2015-12-01

    Knowing how climate change affects the population dynamics of insect pests is critical for the future of integrated pest management. Rising winter temperatures from global warming can drive increases in outbreaks of some agricultural pests. In contrast, here we propose an alternative hypothesis that both extremely cold and warm winters can mismatch the timing between the eclosion of overwintering pests and the flowering of key host plants. As host plants normally need higher effective cumulative temperatures for flowering than insects need for eclosion, changes in flowering time will be less dramatic than changes in eclosion time, leading to a mismatch of phenology on either side of the optimal winter temperature. We term this the "seesaw effect." Using a long-term dataset of the Old World cotton bollworm Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in northern China, we tested this seesaw hypothesis by running a generalized additive model for the effects of the third generation moth in the preceding year, the winter air temperature, the number of winter days below a critical temperature and cumulative precipitation during winter on the demography of the overwintering moth. Results confirmed the existence of the seesaw effect of winter temperature change on overwintering populations. Pest management should therefore consider the indirect effect of changing crop phenology (whether due to greenhouse cultivation or to climate change) on pest outbreaks. As arthropods from mid- and high latitudes are actually living in a cooler thermal environment than their physiological optimum in contrast to species from lower latitudes, the effects of rising winter temperatures on the population dynamics of arthropods in the different latitudinal zones should be considered separately. The seesaw effect makes it more difficult to predict the average long-term population dynamics of insect pests at high latitudes due to the potential sharp changes in annual growth rates

  5. PMP-1 Report: the Fourth Winter of PMP-1, 1981 - 1982: a Winter with Several Interesting Features

    NASA Technical Reports Server (NTRS)

    Labitzke, K.

    1982-01-01

    A synoptic description is given for the fourth winter of pre-MAP project 1 (PMP-1), 1981/82. The main characteristics of this winter are a Canadian warming in the beginning of December, a very strong minor warming in January, and an early final warming in mid-March. The eddy momentum budget, calculated from the daily height and temperature charts, is discussed in terms of the divergence of the Eliassen-Palm-vector.

  6. Winter Workshop.

    ERIC Educational Resources Information Center

    Council of Outdoor Educators of Quebec, Montreal.

    Materials on 11 topics presented at a winter workshop for Quebec outdoor educators have been compiled into this booklet. Action story, instant replay, shoe factory, sound and action, and find an object to fit the description are described and recommended as group dynamic activities. Directions for five games (Superlative Selection; Data…

  7. Winter Wonderlands

    ERIC Educational Resources Information Center

    Coy, Mary

    2011-01-01

    Listening to people complain about the hardships of winter and the dreariness of the nearly constant gray sky prompted the author to help her sixth graders recognize and appreciate the beauty that surrounds them for nearly five months of the year in western New York. The author opines that if students could see things more artistically, the winter…

  8. Winter Games.

    ERIC Educational Resources Information Center

    Tarbuth, Lawson, Comp.

    Educators may find activities for indoor and outdoor winter programs in the games of the traditional Eskimo. These games are dominated by few-step operations and low level structural organization. For the most part they are quickly organized, begun, terminated, and ready to be recommenced. All types of games can be found, including quiet ones,…

  9. Effects of extreme spring temperatures on phenology: a case study from Munich and Ingolstadt

    NASA Astrophysics Data System (ADS)

    Jochner, Susanne; Menzel, Annette

    2010-05-01

    Extreme events - e.g. warm spells or heavy precipitation events - are likely to increase in the future both in frequency and intensity. Therefore, research on extreme events gains new importance; also in terms of plant development which is mostly triggered by temperatures. An arising question is how plants respond to an extreme warm spell when following an extreme cold winter season. This situation could be studied in spring 2009 in the greater area of Munich and Ingolstadt by phenological observations of flowering and leaf unfolding of birch (Betula pendula L.) and flowering of horse chestnut (Aesculus hippocastanum L.). The long chilling period of winter 2008 and spring 2009 was followed by an immediate strong forcing of flowering and leaf unfolding, especially for birch. This extreme weather situation diminished the difference between urban and rural dates of onset. Another important fact that could be observed in the proceeding period of December 2008 to April 2009 was the reduced temperature difference among urban and rural sites (urban heat island effect). Long-term observations (1951-2008) of the phenological network of the German Meteorological Service (DWD) were used to identify years with reduced urban-rural differences between onset times in the greater area of Munich in the past. Statistical analyses were conducted in order to answer the question whether the sequence of extreme warm and cold events leads to a decreased difference in phenological onset times or if this behaviour can be attributed to extreme warm springs themselves or to the decreased urban heat island effect which is mostly affected by general atmospheric circulation patterns.

  10. The State of the Warm and Cold Gas in the Extreme Starburst at the Core of the Phoenix Galaxy Cluster (SPT-CLJ2344-4243)

    NASA Astrophysics Data System (ADS)

    McDonald, Michael; Swinbank, Mark; Edge, Alastair C.; Wilner, David J.; Veilleux, Sylvain; Benson, Bradford A.; Hogan, Michael T.; Marrone, Daniel P.; McNamara, Brian R.; Wei, Lisa H.; Bayliss, Matthew B.; Bautz, Marshall W.

    2014-03-01

    We present new optical integral field spectroscopy (Gemini South) and submillimeter spectroscopy (Submillimeter Array) of the central galaxy in the Phoenix cluster (SPT-CLJ2344-4243). This cluster was previously reported to have a massive starburst (~800 M ⊙ yr-1) in the central, brightest cluster galaxy, most likely fueled by the rapidly cooling intracluster medium. These new data reveal a complex emission-line nebula, extending for >30 kpc from the central galaxy, detected at [O II]λλ3726, 3729, [O III]λλ4959, 5007, Hβ, Hγ, Hδ, [Ne III]λ3869, and He II λ4686. The total Hα luminosity, assuming Hα/Hβ = 2.85, is L Hα = 7.6 ± 0.4 ×1043 erg s-1, making this the most luminous emission-line nebula detected in the center of a cool core cluster. Overall, the relative fluxes of the low-ionization lines (e.g., [O II], Hβ) to the UV continuum are consistent with photoionization by young stars. In both the center of the galaxy and in a newly discovered highly ionized plume to the north of the galaxy, the ionization ratios are consistent with both shocks and active galactic nucleus (AGN) photoionization. We speculate that this extended plume may be a galactic wind, driven and partially photoionized by both the starburst and central AGN. Throughout the cluster we measure elevated high-ionization line ratios (e.g., He II/Hβ, [O III]/Hβ), coupled with an overall high-velocity width (FWHM gsim 500 km s-1), suggesting that shocks are likely important throughout the interstellar medium of the central galaxy. These shocks are most likely driven by a combination of stellar winds from massive young stars, core-collapse supernovae, and the central AGN. In addition to the warm, ionized gas, we detect a substantial amount of cold, molecular gas via the CO(3-2) transition, coincident in position with the galaxy center. We infer a molecular gas mass of M_{H_2} = 2.2 ± 0.6 × 1010 M ⊙, which implies that the starburst will consume its fuel in ~30 Myr if it is not

  11. The state of the warm and cold gas in the extreme starburst at the core of the Phoenix galaxy cluster (SPT-CLJ2344-4243)

    SciTech Connect

    McDonald, Michael; Bautz, Marshall W.; Swinbank, Mark; Edge, Alastair C.; Hogan, Michael T.; Wilner, David J.; Bayliss, Matthew B.; Veilleux, Sylvain; Benson, Bradford A.; Marrone, Daniel P.; McNamara, Brian R.; Wei, Lisa H.

    2014-03-20

    We present new optical integral field spectroscopy (Gemini South) and submillimeter spectroscopy (Submillimeter Array) of the central galaxy in the Phoenix cluster (SPT-CLJ2344-4243). This cluster was previously reported to have a massive starburst (∼800 M {sub ☉} yr{sup –1}) in the central, brightest cluster galaxy, most likely fueled by the rapidly cooling intracluster medium. These new data reveal a complex emission-line nebula, extending for >30 kpc from the central galaxy, detected at [O II]λλ3726, 3729, [O III]λλ4959, 5007, Hβ, Hγ, Hδ, [Ne III]λ3869, and He II λ4686. The total Hα luminosity, assuming Hα/Hβ = 2.85, is L {sub Hα} = 7.6 ± 0.4 ×10{sup 43} erg s{sup –1}, making this the most luminous emission-line nebula detected in the center of a cool core cluster. Overall, the relative fluxes of the low-ionization lines (e.g., [O II], Hβ) to the UV continuum are consistent with photoionization by young stars. In both the center of the galaxy and in a newly discovered highly ionized plume to the north of the galaxy, the ionization ratios are consistent with both shocks and active galactic nucleus (AGN) photoionization. We speculate that this extended plume may be a galactic wind, driven and partially photoionized by both the starburst and central AGN. Throughout the cluster we measure elevated high-ionization line ratios (e.g., He II/Hβ, [O III]/Hβ), coupled with an overall high-velocity width (FWHM ≳ 500 km s{sup –1}), suggesting that shocks are likely important throughout the interstellar medium of the central galaxy. These shocks are most likely driven by a combination of stellar winds from massive young stars, core-collapse supernovae, and the central AGN. In addition to the warm, ionized gas, we detect a substantial amount of cold, molecular gas via the CO(3-2) transition, coincident in position with the galaxy center. We infer a molecular gas mass of M{sub H{sub 2}} = 2.2 ± 0.6 × 10{sup 10} M {sub ☉}, which implies that

  12. Titan's Winter Polar Vortex

    NASA Technical Reports Server (NTRS)

    Flasar, F.M.; Achterberg, R.K.; Schinder, P.J.

    2008-01-01

    Titan's atmosphere has provided an interesting study in contrasts and similarities with Earth's. While both have N$_2$ as the dominant constituent and comparable surface pressures $\\sim1$ bar, Titan's next most abundant molecule is CH$_4$, not O$_2$, and the dissociative breakup of CH$_4$ and N$_2$ by sunlight and electron impact leads to a suite of hydrocarbons and nitriles, and ultimately the photochemical smog that enshrouds the moon. In addition, with a 15.95-day period, Titan is a slow rotator compared to Earth. While the mean zonal terrestrial winds are geostrophic, Titan's are mostly cyclostrophic, whipping around the moon in as little as 1 day. Despite the different dynamical regime, Titan's winter stratosphere exhibits several characteristics that should be familiar to terrestrial meteorologists. The cold winter pole near the 1 -mbar level is circumscribed by strong winds (up to 190 m/s) that act as a barrier to mixing with airmasses at lower latitudes. There is evidence of enhancement of several organic species over the winter pole, indicating subsidence. The adiabatic heating associated with this subsidence gives rise to a warm anomaly at the 0.01-mbar level, raising the stratopause two scale heights above its location at equatorial latitudes. Condensate ices have been detected in Titan's lower stratosphere within the winter polar vortex from infrared spectra. Although not always unambiguously identified, their spatial distribution exhibits a sharp gradient, decreasing precipitously across the vortex away from the winter pole. The interesting question of whether there is important heterogeneous chemistry occurring within the polar vortex, analogous to that occurring in the terrestrial polar stratospheric clouds in the ozone holes, has not been addressed. The breakup of Titan's winter polar vortex has not yet been observed. On Earth, the polar vortex is nonlinearly disrupted by interaction with large-amplitude planetary waves. Large-scale waves have not

  13. Winter mortality and its causes.

    PubMed

    Keatinge, W R

    2002-11-01

    In the 1970s scientific research focussed for the first time on dramatic rises in mortality every winter, and on smaller rises in unusually hot weather. Following the recent decline in influenza epidemics, approximately half of excess winter deaths are due to coronary thrombosis. These peak about two days after the peak of a cold spell. Approximately half the remaining winter deaths are caused by respiratory disease, and these peak about 12 days after peak cold. The rapid coronary deaths are due mainly to haemoconcentration resulting from fluid shifts during cold exposure; some later coronary deaths are secondary to respiratory disease. Heat related deaths often result from haemoconcentration resulting from loss of salt and water in sweat. With the possible exception of some tropical countries, global warming can be expected to reduce cold related deaths more than it increases the rarer heat related deaths, but statistics on populations in different climates suggest that, given time, people will adjust to global warming with little change in either mortality. Some measures may be needed to control insect borne diseases during global warming, but current indications are that cold will remain the main environmental cause of illness and death. Air pollution in cities may also still be causing some deaths, but these are hard to differentiate from the more numerous deaths due to associated cold weather, and clear identification of pollution deaths may need more extensive data than is currently available.

  14. Learning through a Winter's Tale

    ERIC Educational Resources Information Center

    Vidotto, Kristie

    2010-01-01

    In this article, the author shares her experience during the final semester of Year 11 Theatre Studies when she performed a monologue about Hermione from "The Winter's Tale". This experience was extremely significant to her because it nearly made her lose faith in one of the most important parts of her life, drama. She believes this experience,…

  15. Characterizing the Response of Fluvial Systems to Extreme Global Warming During the Early Eocene Climatic Optimum: An Analysis of the Wasatch and Green River Formations, Uinta Basin, UT

    NASA Astrophysics Data System (ADS)

    Jones, E. R.; Plink-Bjorklund, P.

    2013-12-01

    The Wasatch and Green River Formations in the Uinta Basin, UT contain fluvial sandstones that record changes in terrestrial sedimentation coincident with Paleocene-Eocene Thermal Maximum (PETM) and at least six post-PETM hyperthermal climate change events. While proxies for chemical weathering rates during the PETM have been developed using the marine osmium isotope record, to date there has been little research on chemical weathering rates in proximal terrestrial depocenters. This work is one part of a multi-proxy research effort combining quantitative petrographic analysis, the stable carbon isotope record, and a high-resolution stratigraphic and sedimentologic framework across the southern margin of the Uinta Basin. Relative tectonic quiescence in the Uinta Basin during the Early Eocene suggests that climate is the forcing mechanism controlling fluvial architecture and composition, and gradual basin subsidence has preserved at least six pulses of greenhouse climate change during the Early Eocene Climatic Optimum (EECO). Terrestrial records of PETM climate do not support a humid climate with increased precipitation as previously suggested from marine proxies of climate change. Instead, terrestrial records of the PETM climate show evidence of prolonged drought punctuated by intense terrestrial flooding events in mid-latitude continental interiors. Increases in chemical weathering rates during the PETM due to increased temperature and average precipitation is cited as a key carbon sink to initiate a recovery phase where atmospheric CO2 returned to normal concentrations. If terrestrial records of chemical weathering rates differ substantially from marine proxies the carbon-cycle dynamics active during the EECO must be reconsidered. Initial results of this study show that these peak hyperthermal climate change conditions in the Uinta Basin preserve more compositionally and texturally immature sediments due to extremely high erosion and deposition rates, and subdued

  16. Physical characteristics of Eurasian winter temperature variability

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Yul; Son, Seok-Woo

    2016-04-01

    Despite the on-going global warming, recent winters in Eurasian mid-latitudes were much colder than average. In an attempt to better understand the physical characteristics for cold Eurasian winters, major sources of variability in surface air temperature (SAT) are investigated based on cyclostationary EOF analysis. The two leading modes of SAT variability represent the effect of Arctic amplification (AA) and the Arctic oscillation (AO), respectively. These two modes are distinct in terms of the physical characteristics, including surface energy fluxes and tropospheric circulations, and result in significantly different winter SAT patterns over the Eurasian continent. The AA-related SAT anomalies are dipolar with warm Arctic, centered at the Barents–Kara Seas, and cold East Asia. In contrast, the negative AO-related SAT anomalies are characterized by widespread cold anomalies in Northern Eurasia. Relative importance of the AA and the negative AO contributions to cold Eurasian winters is sensitive to the region of interest.

  17. Amplitude and frequency of temperature extremes over the North Atlantic region

    NASA Astrophysics Data System (ADS)

    Nogaj, M.; Yiou, P.; Parey, S.; Malek, F.; Naveau, P.

    2006-05-01

    Recent studies on extreme events have focused on the potential change of their intensity during the 20th century, but their frequency evolution has often been overlooked although its socio-economic impact is equally important. This paper focuses on extreme events of high and low temperatures and their amplitude and frequency changes over the last 60 years in the North Atlantic (NA) region. We analyze the temporal evolution of the amplitude and frequency of extreme events through the parameters of an extreme value distribution applied to NCEP reanalysis for the winter and summer seasons. We examine the relation of the statistics of extremes with greenhouse gas forcing and an atmospheric circulation index and obtain a spatial distribution of the trends of those extreme parameters. We find that the frequency of warm extremes increases over most of the NA while their magnitude does not vary as systematically. Apart from the Labrador Sea and parts of Scandinavia, the features of winter cold extremes exhibit decreasing or no trends.

  18. Increased hurricane activity during the Early Toarcian extreme warmth

    NASA Astrophysics Data System (ADS)

    Bodin, Stephane; Krencker, Francois-Nicolas; Suan, Guillaume; Heimhofer, Ulrich; Immenhauser, Adrian

    2014-05-01

    Theoretical considerations led to the postulation that hurricane activity should increase on a warming planet. Finding physical proof for this relationship remains, however, a difficult task since no clear trend is yet emerging from records of present-day anthropogenic warming. The geological past offers the opportunity to test this hypothesis by assessing episodes of extreme warming events, such as the Toarcian Oceanic Anoxic Event (T-OAE, Early Jurassic, ca. 180 Ma). The T-OAE is characterized by a rapid 4-5°C global warming likely induced by the massive release of greenhouse gases into the atmosphere as a consequence of the activity of the Karoo-Ferrar large igneous province. Within the western Tethyan realm (Morocco, Portugal, France, England, etc.), a systematic increase in the occurrence of storm-related deposits is observed within the shallow-water sediments deposited during the T-OAE, notably at its onset. Increased tempestite occurrences can be observed in both siliciclastic- and carbonate-dominated environments. In the Moroccan High Atlas, hummocky cross-stratification (HCS) occurs ubiquitous within the T-OAE, but is otherwise rare in this tide-dominated basin. Interestingly, the palaeolatitude of the High Atlas Basin (10°N during the Early Jurassic) rules out winter storms as the driving mechanism behind the formation of the HCS, and suggests therefore a significant increase of tropical hurricane activity associated with the Early Toarcian global warming.

  19. Simulated trends of extreme climate indices for the Carpathian basin using outputs of different regional climate models

    NASA Astrophysics Data System (ADS)

    Pongracz, R.; Bartholy, J.; Szabo, P.; Pieczka, I.; Torma, C. S.

    2009-04-01

    Regional climatological effects of global warming may be recognized not only in shifts of mean temperature and precipitation, but in the frequency or intensity changes of different climate extremes. Several climate extreme indices are analyzed and compared for the Carpathian basin (located in Central/Eastern Europe) following the guidelines suggested by the joint WMO-CCl/CLIVAR Working Group on climate change detection. Our statistical trend analysis includes the evaluation of several extreme temperature and precipitation indices, e.g., the numbers of severe cold days, winter days, frost days, cold days, warm days, summer days, hot days, extremely hot days, cold nights, warm nights, the intra-annual extreme temperature range, the heat wave duration, the growing season length, the number of wet days (using several threshold values defining extremes), the maximum number of consecutive dry days, the highest 1-day precipitation amount, the greatest 5-day rainfall total, the annual fraction due to extreme precipitation events, etc. In order to evaluate the future trends (2071-2100) in the Carpathian basin, daily values of meteorological variables are obtained from the outputs of various regional climate model (RCM) experiments accomplished in the frame of the completed EU-project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). Horizontal resolution of the applied RCMs is 50 km. Both scenarios A2 and B2 are used to compare past and future trends of the extreme climate indices for the Carpathian basin. Furthermore, fine-resolution climate experiments of two additional RCMs adapted and run at the Department of Meteorology, Eotvos Lorand University are used to extend the trend analysis of climate extremes for the Carpathian basin. (1) Model PRECIS (run at 25 km horizontal resolution) was developed at the UK Met Office, Hadley Centre, and it uses the boundary conditions from the HadCM3 GCM. (2) Model Reg

  20. Explaining unusual winter lightning in Japan

    NASA Astrophysics Data System (ADS)

    Shindo, Takatoshi; Ishii, Masaru; Williams, Earle

    2011-11-01

    Third International Symposium on Winter Lightning; Sapporo, Japan, 15-16 June 2011 Japan's meteorological setting in winter is unusual: It is an island in a relatively warm sea frequently overswept by colder air from Siberia. This sets up appreciable atmospheric instability in the fringe of the land adjacent to the Sea of Japan. Heavy snowstorms overlap the edge of the island and produce extraordinarily energetic lightning flashes that initiate from points on the ground (known as ground-to-cloud (GC) strokes) and wreak havoc on power lines and, more recently, wind turbines. These troublesome and costly conditions set the stage for the third in a series of conferences on winter lightning.

  1. Cosmic Rays, the Black Pole and Extreme Climate.

    NASA Astrophysics Data System (ADS)

    Ely, J.

    2001-04-01

    The Magnetic Coupling Model predicts many climate anomalies due to solar oscillations (from gravitational torque impulses), galactic cosmic ray modulations, etc, back thru the Pleistocene. A major process in this era is Hale cycle reconnection of solar and galactic B, causing strong recurring "Cirrus Holes." These: shift pressure centers, making drought cycles, record floods, etc; disguised global warming (causing disunity on its reality) by high contrast (deglaciating) climate in the northern hemisphere in alternate sunspot cycles. Fossil fuel CO2 ended major ice ages and risks imminent rapid (decade) CO2 runaway via sea surface exchange (see refs: Ely, Session A8, APS Mtg March 2001; Bette Hileman, Chem Eng News 9, Apr 24, 2000; Ely, Proc. IEEE Conf. Oceans '91, 3: 1658-1665, 1991) Polar regions warm much more in summer than the global averages and now, having lost snow cover, in the Arctic radiate as a black body in winter becoming extremely cold. Hence, altho the record highest average first quarter year US temperature was in April 2000, the most severe US winter ever recorded began in Nov, due to polar breakthrough. Using fossil fuel to survive the winter, hastens the 6m sea level rise.

  2. Winter leaf reddening in 'evergreen' species.

    PubMed

    Hughes, Nicole M

    2011-05-01

    Leaf reddening during autumn in senescing, deciduous tree species has received widespread attention from the public and in the scientific literature, whereas leaf reddening in evergreen species during winter remains largely ignored. Winter reddening can be observed in evergreen herbs, shrubs, vines and trees in Mediterranean, temperate, alpine, and arctic regions, and can persist for several months before dissipating with springtime warming. Yet, little is known about the functional significance of this colour change, or why it occurs in some species but not others. Here, the biochemistry, physiology and ecology associated with winter leaf reddening are reviewed, with special focus on its possible adaptive function. Photoprotection is currently the favoured hypothesis for winter reddening, but alternative explanations have scarcely been explored. Intraspecific reddening generally increases with sunlight incidence, and may also accompany photosynthetic inferiority in photosynthetically 'weak' (e.g. low-nitrogen) individuals. Red leaves tend to show symptoms of shade acclimation relative to green, consistent with a photoprotective function. However, winter-red and winter-green species often cohabitate the same high-light environments, and exhibit similar photosynthetic capacities. The factors dictating interspecific winter leaf colouration therefore remain unclear. Additional outstanding questions and future directions are also highlighted, and possible alternative functions of winter reddening discussed.

  3. Global Warming?

    ERIC Educational Resources Information Center

    Eichman, Julia Christensen; Brown, Jeff A.

    1994-01-01

    Presents information and data on an experiment designed to test whether different atmosphere compositions are affected by light and temperature during both cooling and heating. Although flawed, the experiment should help students appreciate the difficulties that researchers face when trying to find evidence of global warming. (PR)

  4. Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA

    SciTech Connect

    LeCain, Daniel; Smith, David; Morgan, Jack; Kimball, Bruce A.; Pendall, Elise; Miglietta, Franco; Liang, Wenju

    2015-02-06

    In order to plan for global changing climate experiments are being conducted in many countries, but few have monitored the effects of the climate change treatments (warming, elevated CO₂) on the experimental plot microclimate. During three years of an eight year study with year-round feedback-controlled infra-red heater warming (1.5/3.0°C day/night) and growing season free-air CO₂ enrichment (600 ppm) in the mixed-grass prairie of Wyoming, USA, we monitored soil, leaf, canopy-air, above-canopy-air temperatures and relative humidity of control and treated experimental plots and evaluated ecologically important temperature differentials. Leaves were warmed somewhat less than the target settings (1.1 & 1.5°C day/night) but soil was warmed more creating an average that matched the target settings extremely well both during the day and night plus the summer and winter. The site typically has about 50% bare or litter covered soil, therefore soil heat transfer is more critical than in dense canopy ecosystems. The Wyoming site commonly has strong winds (5 ms⁻¹ average) and significant daily and seasonal temperature fluctuations (as much as 30°C daily) but the warming system was nearly always able to maintain the set temperatures regardless of abiotic variation. The within canopy-air was only slightly warmed and above canopy-air was not warmed by the system, therefore convective warming was minor. Elevated CO₂ had no direct effect nor interaction with the warming treatment on microclimate. Relative humidity within the plant canopy was only slightly reduced by warming. Soil water content was reduced by warming but increased by elevated CO₂. This study demonstrates the importance of monitoring the microclimate in manipulative field global change experiments so that critical physiological and ecological conclusions can be determined. Highly variable energy demand fluctuations showed that passive IR heater warming systems will not maintain desired warming for much

  5. Microclimatic performance of a free-air warming and CO₂ enrichment experiment in windy Wyoming, USA

    DOE PAGES

    LeCain, Daniel; Smith, David; Morgan, Jack; Kimball, Bruce A.; Pendall, Elise; Miglietta, Franco; Liang, Wenju

    2015-02-06

    In order to plan for global changing climate experiments are being conducted in many countries, but few have monitored the effects of the climate change treatments (warming, elevated CO₂) on the experimental plot microclimate. During three years of an eight year study with year-round feedback-controlled infra-red heater warming (1.5/3.0°C day/night) and growing season free-air CO₂ enrichment (600 ppm) in the mixed-grass prairie of Wyoming, USA, we monitored soil, leaf, canopy-air, above-canopy-air temperatures and relative humidity of control and treated experimental plots and evaluated ecologically important temperature differentials. Leaves were warmed somewhat less than the target settings (1.1 & 1.5°C day/night)more » but soil was warmed more creating an average that matched the target settings extremely well both during the day and night plus the summer and winter. The site typically has about 50% bare or litter covered soil, therefore soil heat transfer is more critical than in dense canopy ecosystems. The Wyoming site commonly has strong winds (5 ms⁻¹ average) and significant daily and seasonal temperature fluctuations (as much as 30°C daily) but the warming system was nearly always able to maintain the set temperatures regardless of abiotic variation. The within canopy-air was only slightly warmed and above canopy-air was not warmed by the system, therefore convective warming was minor. Elevated CO₂ had no direct effect nor interaction with the warming treatment on microclimate. Relative humidity within the plant canopy was only slightly reduced by warming. Soil water content was reduced by warming but increased by elevated CO₂. This study demonstrates the importance of monitoring the microclimate in manipulative field global change experiments so that critical physiological and ecological conclusions can be determined. Highly variable energy demand fluctuations showed that passive IR heater warming systems will not maintain desired warming

  6. -induced continental warming

    NASA Astrophysics Data System (ADS)

    Kamae, Youichi; Watanabe, Masahiro; Kimoto, Masahide; Shiogama, Hideo

    2014-11-01

    In this the second of a two-part study, we examine the physical mechanisms responsible for the increasing contrast of the land-sea surface air temperature (SAT) in summertime over the Far East, as observed in recent decades and revealed in future climate projections obtained from a series of transient warming and sensitivity experiments conducted under the umbrella of the Coupled Model Intercomparison Project phase 5. On a global perspective, a strengthening of land-sea SAT contrast in the transient warming simulations of coupled atmosphere-ocean general circulation models is attributed to an increase in sea surface temperature (SST). However, in boreal summer, the strengthened contrast over the Far East is reproduced only by increasing atmospheric CO2 concentration. In response to SST increase alone, the tropospheric warming over the interior of the mid- to high-latitude continents including Eurasia are weaker than those over the surrounding oceans, leading to a weakening of the land-sea SAT contrast over the Far East. Thus, the increasing contrast and associated change in atmospheric circulation over East Asia is explained by CO2-induced continental warming. The degree of strengthening of the land-sea SAT contrast varies in different transient warming scenarios, but is reproduced through a combination of the CO2-induced positive and SST-induced negative contributions to the land-sea contrast. These results imply that changes of climate patterns over the land-ocean boundary regions are sensitive to future scenarios of CO2 concentration pathways including extreme cases.

  7. Global Warming: Understanding and Teaching the Forecast.

    ERIC Educational Resources Information Center

    Andrews, Bill

    1995-01-01

    A resource for teaching about the consequences of global warming. Discusses feedback from the temperature increase, changes in the global precipitation pattern, effects on agriculture, weather extremes, effects on forests, effects on biodiversity, effects on sea levels, and actions which will help the global community cope with global warming. (LZ)

  8. Human influence on climate in the 2014 southern England winter floods and their impacts

    NASA Astrophysics Data System (ADS)

    Schaller, Nathalie; Kay, Alison L.; Lamb, Rob; Massey, Neil R.; van Oldenborgh, Geert Jan; Otto, Friederike E. L.; Sparrow, Sarah N.; Vautard, Robert; Yiou, Pascal; Ashpole, Ian; Bowery, Andy; Crooks, Susan M.; Haustein, Karsten; Huntingford, Chris; Ingram, William J.; Jones, Richard G.; Legg, Tim; Miller, Jonathan; Skeggs, Jessica; Wallom, David; Weisheimer, Antje; Wilson, Simon; Stott, Peter A.; Allen, Myles R.

    2016-06-01

    A succession of storms reaching southern England in the winter of 2013/2014 caused severe floods and #451 million insured losses. In a large ensemble of climate model simulations, we find that, as well as increasing the amount of moisture the atmosphere can hold, anthropogenic warming caused a small but significant increase in the number of January days with westerly flow, both of which increased extreme precipitation. Hydrological modelling indicates this increased extreme 30-day-average Thames river flows, and slightly increased daily peak flows, consistent with the understanding of the catchment’s sensitivity to longer-duration precipitation and changes in the role of snowmelt. Consequently, flood risk mapping shows a small increase in properties in the Thames catchment potentially at risk of riverine flooding, with a substantial range of uncertainty, demonstrating the importance of explicit modelling of impacts and relatively subtle changes in weather-related risks when quantifying present-day effects of human influence on climate.

  9. Could behaviour and not physiological thermal tolerance determine winter survival of aphids in cereal fields?

    PubMed

    Alford, Lucy; Andrade, Thiago Oliveira; Georges, Romain; Burel, Françoise; van Baaren, Joan

    2014-01-01

    Traits of physiological thermotolerance are commonly measured in the laboratory as predictors of the field success of ectotherms at unfavourable temperatures (e.g. during harsh winters, heatwaves, or under conditions of predicted global warming). Due to being more complicated to measure, behavioural thermoregulation is less commonly studied, although both physiology and behaviour interact to explain the survival of ectotherms. The aphids Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae are commercially important pests of temperate cereal crops. Although coexisting, these species markedly differ in winter success, with R. padi being the most abundant species during cold winters, followed by S. avenae and lastly M. dirhodum. To better understand the thermal physiology and behavioural factors contributing to differential winter success, the lethal temperature (physiological thermotolerance) and the behaviour of aphids in a declining temperature regime (behavioural thermotolerance) of these three species were investigated. Physiological thermotolerance significantly differed between the three species, with R. padi consistently the least cold tolerant and S. avenae the most cold tolerant. However, although the least cold tolerant of the study species, significantly more R. padi remained attached to the host plant at extreme sub-zero temperatures than S. avenae and M. dirhodum. Given the success of anholocyclic R. padi in harsh winters compared to its anholocyclic counterparts, this study illustrates that behavioural differences could be more important than physiological thermotolerance in explaining resistance to extreme temperatures. Furthermore it highlights that there is a danger to studying physiological thermotolerance in isolation when ascertaining risks of ectotherm invasions, the establishment potential of exotic species in glasshouses, or predicting species impacts under climate change scenarios.

  10. Worrying about weird winters.

    PubMed

    Sinclair, Brent

    2014-01-01

    Winter is a key determinant of biological processes in temperate, alpine, and polar environments. Winters are changing, yet we currently lack the knowledge to adequately predict the impacts of climate change on winter biology, or to link winter conditions to the growing-season performance of most organisms. PMID:27580991

  11. New Index for Winter Temperature of the Korean Peninsula and the East Asia based on the atmospheric teleconnection patterns

    NASA Astrophysics Data System (ADS)

    Kim, S. T.; Sohn, S. J.

    2015-12-01

    This study proposes a new index for monitoring and predicting winter temperature of the Korean Peninsula based on dominant atmospheric winter teleconnection modes and the utilization of the index is extended further to representing the East Asia Winter Monsoon (EAWM). Among the teleconnection modes it is found that both East Atlantic (EA) and Western Pacific (WP) modes are most strongly correlated with the Korean winter temperature in a way that the modes are partly associated with change in sea level pressure (SLP) around the Korean Peninsula. Particularly, the EA and WP modes are related with SLP variation over both Siberian High region and the Kuroshio extension region to the east of Japan, respectively. Based on this relationship, the two boxed regions representing the northeast-southwest SLP gradients are determined for the new index, which is found to be related with the EAWM circulation. The SLP gradients control the intensity of surface winds blowing into the Korean Peninsula from the Siberian regions which can transport cold air. The index shows the best performance in representing winter climate not only for the Korean Peninsula but also for the East Asia among the SLP-based EAWM indices. Furthermore, the new index maintains a better correlation with the winter temperature of both the East Asia and Korea over a certain period of years (i.e., running 30 year periods) than other SLP based EAWM indices and also shows good performance in delineating extreme cold/warm winters. The predictability of the new index and its usable potential for winter temperature prediction in coupled climate models are assessed and discussed further.

  12. Global climate change and reindeer: effects of winter weather on the autumn weight and growth of calves.

    PubMed

    Weladji, Robert B; Holand, Øystein

    2003-07-01

    Reindeer/caribou (Rangifer tarandus), which constitute a biological resource of vital importance for the physical and cultural survival of Arctic residents, and inhabit extremely seasonal environments, have received little attention in the global change debate. We investigated how body weight and growth rate of reindeer calves were affected by large-scale climatic variability [measured by the North Atlantic Oscillation (NAO) winter index] and density in one population in central Norway. Body weights of calves in summer and early winter, as well as their growth rate (summer to early winter), were significantly influenced by density and the NAO index when cohorts were in utero. Males were heavier and had higher absolute growth than females, but there was no evidence that preweaning condition of male and female calves were influenced differently by the NAO winter index. Increasing NAO index had a negative effect on calves' body weight and growth rate. Increasing density significantly reduced body weight and growth rate of calves, and accentuated the effect of the NAO winter index. Winters with a higher NAO index are thus severe for reindeer calves in this area and their effects are associated with nutritional stress experienced by the dams during pregnancy or immediately after calving. Moreover, increased density may enhance intra-specific competition and limits food available at the individual level within cohorts. We conclude that if the current pattern of global warming continues, with greater change occurring in northern latitudes and during winter as is predicted, reduced body weight of reindeer calves may be a consequence in areas where winters with a high NAO index are severe. This will likely have an effect on the livelihood of many northern indigenous peoples, both economically and culturally.

  13. Spatiotemporal variations of temperature and precipitation extremes in the Poyang Lake basin, China

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Xiao, Mingzhong; Singh, Vijay P.; Wang, Yeqiao

    2016-05-01

    Daily temperature and precipitation data from 15 rain gauges covering a period of 1957-2011 were analyzed using the Mann-Kendall trend test with the aim to investigate changing characteristics of weather extremes in the Poyang Lake basin, the largest freshwater lake in China. Also, the connection between El Niño Southern Oscillation (ENSO) and precipitation extremes is analyzed and possible causes for the connection are briefly discussed. Results indicate that (1) warming, characterized by a decreasing trend in frost days and a significant decrease of temperature extremes defined by lower temperature, in the Poyang Lake basin is observed. Temperature extremes, defined by higher temperature indices such as hot days, exhibit moderate changes with no significant trends. Moreover, warming occurs mainly in the northern part of the Poyang Lake basin; (2) precipitation changes are intensifying as reflected by increasing precipitation extremes. However, these changes are different from 1 month to another and the intensification is found mainly in winter and/or summer months; (3) the influence of ENSO on precipitation changes in the Poyang Lake basin is evident with a time lag of longer than 3 months. This should be due to the fact that higher sea surface temperature tends to trigger the occurrence of convective precipitation regimes. Results of this study are important for modeling the occurrence of precipitation extremes in a changing climate and regional climatic responses to global climate changes.

  14. How extreme are extremes?

    NASA Astrophysics Data System (ADS)

    Cucchi, Marco; Petitta, Marcello; Calmanti, Sandro

    2016-04-01

    High temperatures have an impact on the energy balance of any living organism and on the operational capabilities of critical infrastructures. Heat-wave indicators have been mainly developed with the aim of capturing the potential impacts on specific sectors (agriculture, health, wildfires, transport, power generation and distribution). However, the ability to capture the occurrence of extreme temperature events is an essential property of a multi-hazard extreme climate indicator. Aim of this study is to develop a standardized heat-wave indicator, that can be combined with other indices in order to describe multiple hazards in a single indicator. The proposed approach can be used in order to have a quantified indicator of the strenght of a certain extreme. As a matter of fact, extremes are usually distributed in exponential or exponential-exponential functions and it is difficult to quickly asses how strong was an extreme events considering only its magnitude. The proposed approach simplify the quantitative and qualitative communication of extreme magnitude

  15. Photosynthetic response of Persian Gulf acroporid corals to summer versus winter temperature deviations

    PubMed Central

    Saleh, Abolfazl; Mehdinia, Ali; Shirvani, Arash; Kayal, Mohsen

    2015-01-01

    With on-going climate change, coral susceptibility to thermal stress constitutes a central concern in reefconservation. In the Persian Gulf, coral reefs are confronted with a high seasonal variability in water temperature, and both hot and cold extremes have been associated with episodes of coral bleaching and mortality. Using physiological performance as a measure of coral health, we investigated the thermal susceptibility of the common acroporid, Acropora downingi, near Hengam Island where the temperature oscillates seasonally in the range 20.2–34.2 °C. In a series of two short-term experiments comparing coral response in summer versus winter conditions, we exposed corals during each season (1) to the corresponding seasonal average and extreme temperature levels in a static thermal environment, and (2) to a progressive temperature deviation from the annual mean toward the corresponding extreme seasonal value and beyond in a dynamic thermal environment. We monitored four indictors of coral physiological performance: net photosynthesis (Pn), dark respiration (R), autotrophic capability (Pn/R), and survival. Corals exposed to warming during summer showed a decrease in net photosynthesis and ultimately died, while corals exposed to cooling during winter were not affected in their photosynthetic performance and survival. Coral autotrophic capability Pn/R was lower at the warmer thermal level within eachseason, and during summer compared to winter. Corals exposed to the maximum temperature of summer displayed Pn/R < 1, inferring that photosynthetic performance could not support basal metabolic needs under this environment. Our results suggest that the autotrophic performance of the Persian Gulf A. downingi is sensitive to the extreme temperatures endured in summer, and therefore its populations may be impacted by future increases in water temperature. PMID:26157627

  16. Photosynthetic response of Persian Gulf acroporid corals to summer versus winter temperature deviations.

    PubMed

    Vajed Samiei, Jahangir; Saleh, Abolfazl; Mehdinia, Ali; Shirvani, Arash; Kayal, Mohsen

    2015-01-01

    With on-going climate change, coral susceptibility to thermal stress constitutes a central concern in reefconservation. In the Persian Gulf, coral reefs are confronted with a high seasonal variability in water temperature, and both hot and cold extremes have been associated with episodes of coral bleaching and mortality. Using physiological performance as a measure of coral health, we investigated the thermal susceptibility of the common acroporid, Acropora downingi, near Hengam Island where the temperature oscillates seasonally in the range 20.2-34.2 °C. In a series of two short-term experiments comparing coral response in summer versus winter conditions, we exposed corals during each season (1) to the corresponding seasonal average and extreme temperature levels in a static thermal environment, and (2) to a progressive temperature deviation from the annual mean toward the corresponding extreme seasonal value and beyond in a dynamic thermal environment. We monitored four indictors of coral physiological performance: net photosynthesis (Pn), dark respiration (R), autotrophic capability (Pn/R), and survival. Corals exposed to warming during summer showed a decrease in net photosynthesis and ultimately died, while corals exposed to cooling during winter were not affected in their photosynthetic performance and survival. Coral autotrophic capability Pn/R was lower at the warmer thermal level within eachseason, and during summer compared to winter. Corals exposed to the maximum temperature of summer displayed Pn/R < 1, inferring that photosynthetic performance could not support basal metabolic needs under this environment. Our results suggest that the autotrophic performance of the Persian Gulf A. downingi is sensitive to the extreme temperatures endured in summer, and therefore its populations may be impacted by future increases in water temperature. PMID:26157627

  17. Spatial and temporal changes in daily temperature extremes in China during 1960-2011

    NASA Astrophysics Data System (ADS)

    Shen, Xiangjin; Liu, Binhui; Lu, Xianguo; Fan, Gaohua

    2016-09-01

    Based on daily maximum and minimum temperature data from 437 weather stations over China, this study examined the spatiotemporal change of temperature extremes in China from 1960 to 2011. Results showed a general downward trends in the occurrence of cold days (TX10) and nights (TN10) (base period 1961-1990), but upward tendency on the occurrence of warm days (TX90) and nights (TN90), the temperatures of coldest day (TXn), coldest night (TNn), warmest day (TXx), and warmest night (TNx) in China and most climate regions. At the national scale, TX10 and TN10 have significantly decreased by -1.89 and -4.39 days/decade, and TX90 and TN90 have significantly increased by 2.49 and 4.72 days/decade from 1960 to 2011. The national average trends for TXn, TNn, TXx, and TNx were 0.28, 0.54, 0.17, and 0.27 °C/decade, respectively. The temporal changes of extremes indices showed that changes in cold (warm) relative indices may be primarily related to that of corresponding winter (summer) Tmax and Tmin, respectively. Regionally, the magnitudes of changes in extreme indices decreased from the north to south of China. However, we found significant increase of warm extremes, especially warm days and nights in Southeast China. For most climate regions, the trend magnitudes in warm days/nights were larger than that in cold days/nights, but the trend in coldest temperature was much higher than that in warmest temperature. The trend magnitudes in minimum temperature indices were larger than those based on daily maximum temperature, explaining the faster increase of Tmin than Tmax in China.

  18. A Winter Survival Unit.

    ERIC Educational Resources Information Center

    Phillips, Ronald E.

    1979-01-01

    The article is a condensation of materials from the winter survival unit of a Canadian snow ecology course. The unit covers: cold physiology, frostbite, snowblindness, hypothermia, winter campout, and survival strategies. (SB)

  19. Winter Weather Emergencies

    MedlinePlus

    Severe winter weather can lead to health and safety challenges. You may have to cope with Cold related health problems, including ... there are no guarantees of safety during winter weather emergencies, you can take actions to protect yourself. ...

  20. The 2009-2010 arctic stratospheric winter - general evolution, mountain waves and predictability of an operational weather forecast model

    NASA Astrophysics Data System (ADS)

    Dörnbrack, A.; Pitts, M. C.; Poole, L. R.; Orsolini, Y. J.; Nishii, K.; Nakamura, H.

    2011-12-01

    The relatively warm 2009-2010 Arctic winter was an exceptional one as the North Atlantic Oscillation index attained persistent extreme negative values. Here, selected aspects of the Arctic stratosphere during this winter inspired by the analysis of the international field experiment RECONCILE are presented. First of all, and as a kind of reference, the evolution of the polar vortex in its different phases is documented. Special emphasis is put on explaining the formation of the exceptionally cold vortex in mid winter after a sequence of stratospheric disturbances which were caused by upward propagating planetary waves. A major sudden stratospheric warming (SSW) occurring near the end of January 2010 concluded the anomalous cold vortex period. Wave ice polar stratospheric clouds were frequently observed by spaceborne remote-sensing instruments over the Arctic during the cold period in January 2010. Here, one such case observed over Greenland is analysed in more detail and an attempt is made to correlate flow information of an operational numerical weather prediction model to the magnitude of the mountain-wave induced temperature fluctuations. Finally, it is shown that the forecasts of the ECMWF ensemble prediction system for the onset of the major SSW were very skilful and the ensemble spread was very small. However, the ensemble spread increased dramatically after the major SSW, displaying the strong non-linearity and internal variability involved in the SSW event.

  1. The 2009-2010 Arctic stratospheric winter - general evolution, mountain waves and predictability of an operational weather forecast model

    NASA Astrophysics Data System (ADS)

    Dörnbrack, A.; Pitts, M. C.; Poole, L. R.; Orsolini, Y. J.; Nishii, K.; Nakamura, H.

    2012-04-01

    The relatively warm 2009-2010 Arctic winter was an exceptional one as the North Atlantic Oscillation index attained persistent extreme negative values. Here, selected aspects of the Arctic stratosphere during this winter inspired by the analysis of the international field experiment RECONCILE are presented. First of all, and as a kind of reference, the evolution of the polar vortex in its different phases is documented. Special emphasis is put on explaining the formation of the exceptionally cold vortex in mid winter after a sequence of stratospheric disturbances which were caused by upward propagating planetary waves. A major sudden stratospheric warming (SSW) occurring near the end of January 2010 concluded the anomalous cold vortex period. Wave ice polar stratospheric clouds were frequently observed by spaceborne remote-sensing instruments over the Arctic during the cold period in January 2010. Here, one such case observed over Greenland is analysed in more detail and an attempt is made to correlate flow information of an operational numerical weather prediction model to the magnitude of the mountain-wave induced temperature fluctuations. Finally, it is shown that the forecasts of the ECMWF ensemble prediction system for the onset of the major SSW were very skilful and the ensemble spread was very small. However, the ensemble spread increased dramatically after the major SSW, displaying the strong non-linearity and internal variability involved in the SSW event.

  2. Winter Climate Limits Subantarctic Low Forest Growth and Establishment

    PubMed Central

    Harsch, Melanie A.; McGlone, Matt S.; Wilmshurst, Janet M.

    2014-01-01

    Campbell Island, an isolated island 600 km south of New Zealand mainland (52°S, 169°E) is oceanic (Conrad Index of Continentality  = −5) with small differences between mean summer and winter temperatures. Previous work established the unexpected result that a mean annual climate warming of c. 0.6°C since the 1940's has not led to upward movement of the forest limit. Here we explore the relative importance of summer and winter climatic conditions on growth and age-class structure of the treeline forming species, Dracophyllum longifolium and Dracophyllum scoparium over the second half of the 20th century. The relationship between climate and growth and establishment were evaluated using standard dendroecological methods and local climate data from a meteorological station on the island. Growth and establishment were correlated against climate variables and further evaluated within hierarchical regression models to take into account the effect of plot level variables. Winter climatic conditions exerted a greater effect on growth and establishment than summer climatic conditions. Establishment is maximized under warm (mean winter temperatures >7 °C), dry winters (total winter precipitation <400 mm). Growth, on the other hand, is adversely affected by wide winter temperature ranges and increased rainfall. The contrasting effect of winter warmth on growth and establishment suggests that winter temperature affects growth and establishment through differing mechanisms. We propose that milder winters enhance survival of seedlings and, therefore, recruitment, but increases metabolic stress on established plants, resulting in lower growth rates. Future winter warming may therefore have complex effects on plant growth and establishment globally. PMID:24691026

  3. Winter climate limits subantarctic low forest growth and establishment.

    PubMed

    Harsch, Melanie A; McGlone, Matt S; Wilmshurst, Janet M

    2014-01-01

    Campbell Island, an isolated island 600 km south of New Zealand mainland (52 °S, 169 °E) is oceanic (Conrad Index of Continentality  =  -5) with small differences between mean summer and winter temperatures. Previous work established the unexpected result that a mean annual climate warming of c. 0.6 °C since the 1940's has not led to upward movement of the forest limit. Here we explore the relative importance of summer and winter climatic conditions on growth and age-class structure of the treeline forming species, Dracophyllum longifolium and Dracophyllum scoparium over the second half of the 20th century. The relationship between climate and growth and establishment were evaluated using standard dendroecological methods and local climate data from a meteorological station on the island. Growth and establishment were correlated against climate variables and further evaluated within hierarchical regression models to take into account the effect of plot level variables. Winter climatic conditions exerted a greater effect on growth and establishment than summer climatic conditions. Establishment is maximized under warm (mean winter temperatures >7 °C), dry winters (total winter precipitation <400 mm). Growth, on the other hand, is adversely affected by wide winter temperature ranges and increased rainfall. The contrasting effect of winter warmth on growth and establishment suggests that winter temperature affects growth and establishment through differing mechanisms. We propose that milder winters enhance survival of seedlings and, therefore, recruitment, but increases metabolic stress on established plants, resulting in lower growth rates. Future winter warming may therefore have complex effects on plant growth and establishment globally. PMID:24691026

  4. Recent changes in Serbian climate extreme indices from 1961 to 2010

    NASA Astrophysics Data System (ADS)

    Malinovic-Milicevic, Slavica; Radovanovic, Milan M.; Stanojevic, Gorica; Milovanovic, Bosko

    2016-05-01

    The evolution of daily extreme temperature and precipitation from 1961 to 2010 in Serbia was investigated. Trends of five temperature indices, three precipitation indices, and four combined indices were calculated at ten temperature and ten precipitation stations located within the study area, and their corresponding significances were tested using the Student's t test. Obtained results suggest that the time periods of extremely hot weather last longer, while the periods of extremely cold weather are shortened. Trends of duration of extreme temperature conditions were most pronounced in summer season. Periods of mild weather conditions are extended. Amount and intensity of precipitation had statistically significant increase only during autumn and were most pronounced in the northern and western parts of the country. On an average, there was no significant decrease in the maximum number of consecutive dry days or increase in the wet days (except in autumn). The investigation of four combined temperature-precipitation regimes showed the domination of "dry" regimes over "wet," increasing trend of "warm" regimes and decreasing trend of "cold" regimes. The correlation between the examined extreme indices and the large-scale circulation patterns showed that EA and NAO had significant influence on duration of winter warm periods, while their influence on duration of cold periods cannot be confirmed with certainty.

  5. The impact of global warming on Mount Everest.

    PubMed

    Moore, G W K; Semple, John L

    2009-01-01

    Global warming impacts a wide range of human activities and ecosystems. One unanticipated consequence of the warming is an increase in barometric pressure throughout the troposphere. Mount Everest's extreme height and resulting low barometric pressure places humans near its summit in an extreme state of hypoxia. Here we quantify the degree with which this warming is increasing the barometric pressure near Everest's summit and argue that it is of such a magnitude as to make the mountain, over time, easier to climb.

  6. Novel psychrotolerant picocyanobacteria isolated from Chesapeake Bay in the winter.

    PubMed

    Xu, Yongle; Jiao, Nianzhi; Chen, Feng

    2015-08-01

    Picocyanobacteria are major primary producers in the ocean, especially in the tropical or subtropical oceans or during warm seasons. Many "warm" picocyanobacterial species have been isolated and characterized. However, picocyanobacteria in cold environments or cold seasons are much less studied. In general, little is known about the taxonomy and ecophysiology of picocyanobacteria living in the winter. In this study, 17 strains of picocyanobacteria were isolated from Chesapeake Bay, a temperate estuarine ecosystem, during the winter months. These winter isolates belong to five distinct phylogenetic lineages, and are distinct from the picocyanobacteria previously isolated from the warm seasons. The vast majority of the winter isolates were closely related to picocyanobacteria isolated from other cold environments like Arctic or subalpine waters. The winter picocyanobacterial isolates were able to maintain slow growth or prolonged dormancy at 4°C. Interestingly, the phycoerythrin-rich strains outperformed the phycocyanin-rich strains at cold temperature. In addition, winter picocyanobacteria changed their morphology when cultivated at 4°C. The close phylogenetic relationship between the winter picocyanobacteria and the picocyanobacteria living in high latitude cold regions indicates that low temperature locations select specific ecotypes of picocyanobacteria. PMID:26986796

  7. Novel psychrotolerant picocyanobacteria isolated from Chesapeake Bay in the winter.

    PubMed

    Xu, Yongle; Jiao, Nianzhi; Chen, Feng

    2015-08-01

    Picocyanobacteria are major primary producers in the ocean, especially in the tropical or subtropical oceans or during warm seasons. Many "warm" picocyanobacterial species have been isolated and characterized. However, picocyanobacteria in cold environments or cold seasons are much less studied. In general, little is known about the taxonomy and ecophysiology of picocyanobacteria living in the winter. In this study, 17 strains of picocyanobacteria were isolated from Chesapeake Bay, a temperate estuarine ecosystem, during the winter months. These winter isolates belong to five distinct phylogenetic lineages, and are distinct from the picocyanobacteria previously isolated from the warm seasons. The vast majority of the winter isolates were closely related to picocyanobacteria isolated from other cold environments like Arctic or subalpine waters. The winter picocyanobacterial isolates were able to maintain slow growth or prolonged dormancy at 4°C. Interestingly, the phycoerythrin-rich strains outperformed the phycocyanin-rich strains at cold temperature. In addition, winter picocyanobacteria changed their morphology when cultivated at 4°C. The close phylogenetic relationship between the winter picocyanobacteria and the picocyanobacteria living in high latitude cold regions indicates that low temperature locations select specific ecotypes of picocyanobacteria.

  8. Microclimatic Performance of a Free-Air Warming and CO2 Enrichment Experiment in Windy Wyoming, USA

    PubMed Central

    LeCain, Daniel; Smith, David; Morgan, Jack; Kimball, Bruce A.; Pendall, Elise; Miglietta, Franco

    2015-01-01

    In order to plan for global changing climate experiments are being conducted in many countries, but few have monitored the effects of the climate change treatments (warming, elevated CO2) on the experimental plot microclimate. During three years of an eight year study with year-round feedback-controlled infra-red heater warming (1.5/3.0°C day/night) and growing season free-air CO2 enrichment (600 ppm) in the mixed-grass prairie of Wyoming, USA, we monitored soil, leaf, canopy-air, above-canopy-air temperatures and relative humidity of control and treated experimental plots and evaluated ecologically important temperature differentials. Leaves were warmed somewhat less than the target settings (1.1 & 1.5°C day/night) but soil was warmed more creating an average that matched the target settings extremely well both during the day and night plus the summer and winter. The site typically has about 50% bare or litter covered soil, therefore soil heat transfer is more critical than in dense canopy ecosystems. The Wyoming site commonly has strong winds (5 ms-1 average) and significant daily and seasonal temperature fluctuations (as much as 30°C daily) but the warming system was nearly always able to maintain the set temperatures regardless of abiotic variation. The within canopy-air was only slightly warmed and above canopy-air was not warmed by the system, therefore convective warming was minor. Elevated CO2 had no direct effect nor interaction with the warming treatment on microclimate. Relative humidity within the plant canopy was only slightly reduced by warming. Soil water content was reduced by warming but increased by elevated CO2. This study demonstrates the importance of monitoring the microclimate in manipulative field global change experiments so that critical physiological and ecological conclusions can be determined. Highly variable energy demand fluctuations showed that passive IR heater warming systems will not maintain desired warming for much of the

  9. Precipitation regime and stable oxygen isotopes at Dome C, East Antarctica - a comparison of two extreme years 2009 and 2010

    NASA Astrophysics Data System (ADS)

    Schlosser, E.; Stenni, B.; Valt, M.; Cagnati, A.; Powers, J. G.; Manning, K. W.; Raphael, M.; Duda, M. G.

    2015-11-01

    At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements have been initiated in 2006 and are being continued until today. The amounts and stable isotope ratios of the precipitation samples as well as crystal types are determined. Within the measuring period, the two years 2009 and 2010 showed striking contrasting temperature and precipitation anomalies, particularly in the winter seasons. The reasons for these anomalies and their relation to stable isotope ratios are analysed using data from the mesoscale atmospheric model WRF (Weather Research and Forecasting Model) run under the Antarctic Mesoscale Prediction System (AMPS). 2009 was relatively warm and moist due to frequent warm air intrusions connected to amplification of Rossby waves in the circumpolar westerlies, whereas the winter of 2010 was extremely dry and cold. It is shown that while in 2010 a strong zonal atmospheric flow was dominant, in 2009 an enhanced meridional flow prevailed, which increased the meridional transport of heat and moisture onto the East Antarctic plateau and led to a number of high-precipitation/warming events at Dome C. This was also evident in a positive (negative) SAM index and a negative (positive) ZW3 index during the winter months of 2010 (2009). Changes in the frequency or seasonality of such event-type precipitation can lead to a strong bias in the air temperature derived from stable water isotopes in ice cores.

  10. Precipitation and synoptic regime in two extreme years 2009 and 2010 at Dome C, Antarctica - implications for ice core interpretation

    NASA Astrophysics Data System (ADS)

    Schlosser, Elisabeth; Stenni, Barbara; Valt, Mauro; Cagnati, Anselmo; Powers, Jordan G.; Manning, Kevin W.; Raphael, Marilyn; Duda, Michael G.

    2016-04-01

    At the East Antarctic deep ice core drilling site Dome C, daily precipitation measurements were initiated in 2006 and are being continued until today. The amounts and stable isotope ratios of the precipitation samples as well as crystal types are determined. Within the measuring period, the two years 2009 and 2010 showed striking contrasting temperature and precipitation anomalies, particularly in the winter seasons. The reasons for these anomalies are analysed using data from the mesoscale atmospheric model WRF (Weather Research and Forecasting Model) run under the Antarctic Mesoscale Prediction System (AMPS). 2009 was relatively warm and moist due to frequent warm air intrusions connected to amplification of Rossby waves in the circumpolar westerlies, whereas the winter of 2010 was extremely dry and cold. It is shown that while in 2010 a strong zonal atmospheric flow was dominant, in 2009 an enhanced meridional flow prevailed, which increased the meridional transport of heat and moisture onto the East Antarctic plateau and led to a number of high-precipitation/warming events at Dome C. This was also evident in a positive (negative) SAM (Southern Annular Mode) index and a negative (positive) ZW3 (zonal wave number three) index during the winter months of 2010 (2009). Changes in the frequency or seasonality of such event-type precipitation can lead to a strong bias in the air temperature derived from stable water isotopes in ice cores.

  11. The role of synoptic and intraseasonal anomalies on the life cycle of rainfall extremes over South America: non-summer conditions

    NASA Astrophysics Data System (ADS)

    Hirata, Fernando E.; Grimm, Alice M.

    2016-09-01

    Previous study showed that the interaction of synoptic disturbances with intraseasonal anomalies is important for heavy rainfall in the South Atlantic Convergence Zone and the La Plata basin during the austral summer. Here, we conduct similar analysis to study the evolution of rainfall extremes during austral spring (SON), fall (MAM) and winter (JJA). A relatively homogeneous region over southeastern South America, whose limits change little from season to season, is heavily affected by extreme precipitation events, as indicated by the value of the 95th percentile of daily rainfall, higher during the spring season (16.94 mm day-1) and lower in winter (13.79 mm day-1). From 1979 to 2013, extreme rainfall events are more frequent in spring (131 events) and less frequent in fall (112 events). Similar to summertime extreme events, synoptic-scale waves continue to be the main drivers of extreme precipitation over the region. The interaction between these waves and intraseasonal anomalies during the development of rainfall extremes over southeastern South America is observed especially during neutral ENSO and La Niña conditions. Warm ENSO phases tend to favor more frequent extremes in all three seasons and extreme events during El Niños are associated with synoptic waves, with no significant interaction with intraseasonal anomalies.

  12. Extreme warming, photic zone euxinia and sea level rise during the Paleocene/Eocene Thermal Maximum on the Gulf of Mexico Coastal Plain; connecting marginal marine biotic signals, nutrient cycling and ocean deoxygenation

    NASA Astrophysics Data System (ADS)

    Sluijs, A.; van Roij, L.; Harrington, G. J.; Schouten, S.; Sessa, J. A.; LeVay, L. J.; Reichart, G.-J.; Slomp, C. P.

    2013-12-01

    The Paleocene/Eocene Thermal Maximum (PETM, ~56 Ma) was a ~200 kyr episode of global warming, associated with massive injections of 13C-depleted carbon into the ocean-atmosphere system. Although climate change during the PETM is relatively well constrained, effects on marine oxygen and nutrient cycling remain largely unclear. We identify the PETM in a sediment core from the US margin of the Gulf of Mexico. Biomarker-based paleotemperature proxies (MBT/CBT and TEX86) indicate that continental air and sea surface temperatures warmed from 27-29 °C to ~35 °C, although variations in the relative abundances of terrestrial and marine biomarkers may have influenced the record. Vegetation changes as recorded from pollen assemblages supports profound warming. Lithology, relative abundances of terrestrial vs. marine palynomorphs as well as dinoflagellate cyst and biomarker assemblages indicate sea level rise during the PETM, consistent with previously recognized eustatic rise. The recognition of a maximum flooding surface during the PETM changes regional sequence stratigraphic interpretations, which allows us to exclude the previously posed hypothesis that a nearby fossil found in PETM-deposits represents the first North American primate. Within the PETM we record the biomarker isorenieratane, diagnostic of euxinic photic zone conditions. A global data compilation indicates that deoxygenation occurred in large regions of the global ocean in response to warming, hydrological change, and carbon cycle feedbacks, particularly along continental margins, analogous to modern trends. Seafloor deoxygenation and widespread anoxia likely caused phosphorus regeneration from suboxic and anoxic sediments. We argue that this fuelled shelf eutrophication, as widely recorded from microfossil studies, increasing organic carbon burial along continental margins as a negative feedback to carbon input and global warming. If properly quantified with future work, the PETM offers the opportunity to

  13. Measurements of Chlorine Partitioning in the Winter Arctic Stratosphere

    NASA Technical Reports Server (NTRS)

    Stachnik, R.; Salawitch, R.; Engel, A.; Schmidt, U.

    1999-01-01

    Under the extremely cold conditions in the polar winter stratosphere, heterogeneous reactions involving HCl and CIONO(sub 2) on the surfaces of polar stratospheric cloud particles can release large amounts of reactive chlorine from these reservoirs leading to rapid chemical loss of ozone in the Arctic lower stratosphere during late winter and early spring.

  14. Poleward expansion of mangroves is a threshold response to decreased frequency of extreme cold events

    PubMed Central

    Cavanaugh, Kyle C.; Kellner, James R.; Forde, Alexander J.; Gruner, Daniel S.; Parker, John D.; Rodriguez, Wilfrid; Feller, Ilka C.

    2014-01-01

    Regional warming associated with climate change is linked with altered range and abundance of species and ecosystems worldwide. However, the ecological impacts of changes in the frequency of extreme events have not been as well documented, especially for coastal and marine environments. We used 28 y of satellite imagery to demonstrate that the area of mangrove forests has doubled at the northern end of their historic range on the east coast of Florida. This expansion is associated with a reduction in the frequency of “extreme” cold events (days colder than −4 °C), but uncorrelated with changes in mean annual temperature, mean annual precipitation, and land use. Our analyses provide evidence for a threshold response, with declining frequency of severe cold winter events allowing for poleward expansion of mangroves. Future warming may result in increases in mangrove cover beyond current latitudinal limits of mangrove forests, thereby altering the structure and function of these important coastal ecosystems. PMID:24379379

  15. Distribution of alewives in southeastern Lake Ontario in autumn and winter: a clue to winter mortalities

    USGS Publications Warehouse

    Bergstedt, Roger A.; O'Gorman, Robert

    1989-01-01

    Alewives Alosa pseudoharengus in the Great Lakes are thought to avoid extreme cold in winter by moving to deep water where the temperature is usually highest because of inverse thermal stratification. Information collected in Lake Ontario during autumn and winter 1981–1984 with an echo sounder and bottom and midwater trawls indicated that many alewives remained at depths above 110 m, regardless of water temperature. Alewives in the Great Lakes that did not descend to greater depths would be exposed to potentially lethal temperatures during cold winters.inters.

  16. Global Warming And Meltwater

    NASA Astrophysics Data System (ADS)

    Bratu, S.

    2012-04-01

    glaciers, permafrost and sea ice. Other likely effects of the warming include more frequent occurrences of extreme weather events including heat waves, droughts and heavy rainfall events, species extinctions due to shifting temperature regimes, and changes in agricultural yields. Meltwater is the water released by the melting of snow or ice, including glacial ice and ice shelves in the oceans. Meltwater is often found in the ablation zone of glaciers, where the rate of snow cover is reduced. In a report published in June 2007, the United Nations Environment Program estimated that global warming could lead to 40% of the world's population being affected by the loss of glaciers, snow and the associated meltwater in Asia. This is one of many activities of the physics laboratory that the students of our high school are involved in.

  17. Modeling the Pineapple Express phenomenon via Multivariate Extreme Value Theory

    NASA Astrophysics Data System (ADS)

    Weller, G.; Cooley, D. S.

    2011-12-01

    The pineapple express (PE) phenomenon is responsible for producing extreme winter precipitation events in the coastal and mountainous regions of the western United States. Because the PE phenomenon is also associated with warm temperatures, the heavy precipitation and associated snowmelt can cause destructive flooding. In order to study impacts, it is important that regional climate models from NARCCAP are able to reproduce extreme precipitation events produced by PE. We define a daily precipitation quantity which captures the spatial extent and intensity of precipitation events produced by the PE phenomenon. We then use statistical extreme value theory to model the tail dependence of this quantity as seen in an observational data set and each of the six NARCCAP regional models driven by NCEP reanalysis. We find that most NCEP-driven NARCCAP models do exhibit tail dependence between daily model output and observations. Furthermore, we find that not all extreme precipitation events are pineapple express events, as identified by Dettinger et al. (2011). The synoptic-scale atmospheric processes that drive extreme precipitation events produced by PE have only recently begun to be examined. Much of the current work has focused on pattern recognition, rather than quantitative analysis. We use daily mean sea-level pressure (MSLP) fields from NCEP to develop a "pineapple express index" for extreme precipitation, which exhibits tail dependence with our observed precipitation quantity for pineapple express events. We build a statistical model that connects daily precipitation output from the WRFG model, daily MSLP fields from NCEP, and daily observed precipitation in the western US. Finally, we use this model to simulate future observed precipitation based on WRFG output driven by the CCSM model, and our pineapple express index derived from future CCSM output. Our aim is to use this model to develop a better understanding of the frequency and intensity of extreme

  18. Stationary Wave Interference and its Relation to Tropical Convection and Climate Extremes

    NASA Astrophysics Data System (ADS)

    Feldstein, S. B.; Goss, M.; Lee, S.

    2015-12-01

    The impact of interference between transient eddies and the climatological stationary eddies is examined with ERA-Interim Reanalysis data. Composite calculations show that constructive interference during winter occurs about one week after enhanced Warm Pool convection, and is followed by the excitation of the positive phase of the Pacific/North American teleconnection pattern, an increase in surface air temperature over much of the extratropical Northern Hemisphere, along with a reduction of sea ice in the Barents and Kara Seas, a deceleration of the stratospheric polar vortex, and the excitation of the negative phase of the Arctic Oscillation. This surface warming does occur without prior Warm Pool convection, but it is enhanced and prolonged when constructive interference occurs in concert with the convection. This suggests that climate extremes may be more likely to occur when particular processes, such as Warm Pool convection and constructive interference, occur together. Opposite features are observed when there is destructive interference. To further investigate the influence of tropical convection, a series of idealized multi-level primitive equation model calculations is performed. The model's heating profiles are determined from composite CMAP precipitation anomalies for La Niña and El Niño months, and for MJO phase 1 and phase 5. As in the atmosphere, the model calculations find extratropical 300-hPa geopotential height anomalies of opposite sign for MJO phase 1 and El Nino heating, even though the heating profiles closely resemble each other. (Analogous results were found for MJO phase 5 and La Nina.) The model was also run with individual heating anomalies in key geographic locations. The results suggest that the extratropical response to both ENSO and MJO convective heating anomalies can be understood as arising from the competing influences of Warm Pool and central Pacific tropical convection. These results allude to the possibility that the

  19. Global warming: it's not only size that matters

    NASA Astrophysics Data System (ADS)

    Hegerl, Gabriele C.

    2011-09-01

    impacts than temperatures that have occurred frequently due to internal climate variability. Determining when exactly temperatures enter unusual ranges may be done in many different ways (and the paper shows several, and more could be imagined), but the main result of first local emergence in low latitudes remains robust. A worrying factor is that the regions where the signal is expected to emerge first, or is already emerging are largely regions in Africa, parts of South and Central America, and the Maritime Continent; regions that are vulnerable to climate change for a variety of regions (see IPCC 2007), and regions which contribute generally little to global greenhouse gas emissions. In contrast, strong emissions of greenhouse gases occur in regions of low warming-to-variability ratio. To get even closer to the relevance of this finding for impacts, it would be interesting to place the emergence of highly unusual summer temperatures in the context not of internal variability, but in the context of variability experienced by the climate system prior to the 20th century, as, e.g. documented in palaeoclimatic reconstructions and simulated in simulations of the last millennium (see Jansen et al 2007). External forcing has moved the temperature range around more strongly for some regions and in some seasons than others. For example, while reconstructions of summer temperatures in Europe appear to show small long-term variations, winter shows deep drops in temperature in the little Ice Age and a long-term increase since then (Luterbacher et al 2004), which was at least partly caused by external forcing (Hegerl et al 2011a) and therefore 'natural variability' may be different from internal variability. A further interesting question in attempts to provide a climate-based proxy for impacts of climate change is: to what extent does the rapidity of change matter, and how does it compare to trends due to natural variability? It is reasonable to assume that fast changes impact

  20. Synoptic climatological study on precipitation in the Hokuriku District of Central Japan associated with the cold air outbreak in early winter (With Comparison to that in midwinter for the 1983/1984 winter)

    NASA Astrophysics Data System (ADS)

    Kato, Kuranoshin; Nishimura, Nanako; Haga, Yuichi

    2014-05-01

    . According to the case study for 1983/84 winter, although the "wintertime pressure pattern" appeared rather frequently already from early November, each event of that pattern tended to persist only a several days. In addition, the organization of the shallow convective clouds in the cold air outbreak situation as often found in midwinter was not clearly observed. However, strong cold air advection in early winter as in midwinter over the warm underlying sea, at least in the mature stage of each "wintertime pressure situation", seems to enable the extremely huge amount of LH and the equivalently intense SH to that in midwinter, resulting in the large daily precipitation there through the enhancement of the air mass transformation process over the Japan Sea.

  1. Warming shifts 'worming': effects of experimental warming on invasive earthworms in northern North America.

    PubMed

    Eisenhauer, Nico; Stefanski, Artur; Fisichelli, Nicholas A; Rice, Karen; Rich, Roy; Reich, Peter B

    2014-01-01

    Climate change causes species range shifts and potentially alters biological invasions. The invasion of European earthworm species across northern North America has severe impacts on native ecosystems. Given the long and cold winters in that region that to date supposedly have slowed earthworm invasion, future warming is hypothesized to accelerate earthworm invasions into yet non-invaded regions. Alternatively, warming-induced reductions in soil water content (SWC) can also decrease earthworm performance. We tested these hypotheses in a field warming experiment at two sites in Minnesota, USA by sampling earthworms in closed and open canopy in three temperature treatments in 2010 and 2012. Structural equation modeling revealed that detrimental warming effects on earthworm densities and biomass could indeed be partly explained by warming-induced reductions in SWC. The direction of warming effects depended on the current average SWC: warming had neutral to positive effects at high SWC, whereas the opposite was true at low SWC. Our results suggest that warming limits the invasion of earthworms in northern North America by causing less favorable soil abiotic conditions, unless warming is accompanied by increased and temporally even distributions of rainfall sufficient to offset greater water losses from higher evapotranspiration. PMID:25363633

  2. Warming shifts 'worming': effects of experimental warming on invasive earthworms in northern North America.

    PubMed

    Eisenhauer, Nico; Stefanski, Artur; Fisichelli, Nicholas A; Rice, Karen; Rich, Roy; Reich, Peter B

    2014-11-03

    Climate change causes species range shifts and potentially alters biological invasions. The invasion of European earthworm species across northern North America has severe impacts on native ecosystems. Given the long and cold winters in that region that to date supposedly have slowed earthworm invasion, future warming is hypothesized to accelerate earthworm invasions into yet non-invaded regions. Alternatively, warming-induced reductions in soil water content (SWC) can also decrease earthworm performance. We tested these hypotheses in a field warming experiment at two sites in Minnesota, USA by sampling earthworms in closed and open canopy in three temperature treatments in 2010 and 2012. Structural equation modeling revealed that detrimental warming effects on earthworm densities and biomass could indeed be partly explained by warming-induced reductions in SWC. The direction of warming effects depended on the current average SWC: warming had neutral to positive effects at high SWC, whereas the opposite was true at low SWC. Our results suggest that warming limits the invasion of earthworms in northern North America by causing less favorable soil abiotic conditions, unless warming is accompanied by increased and temporally even distributions of rainfall sufficient to offset greater water losses from higher evapotranspiration.

  3. Warming shifts `worming': effects of experimental warming on invasive earthworms in northern North America

    NASA Astrophysics Data System (ADS)

    Eisenhauer, Nico; Stefanski, Artur; Fisichelli, Nicholas A.; Rice, Karen; Rich, Roy; Reich, Peter B.

    2014-11-01

    Climate change causes species range shifts and potentially alters biological invasions. The invasion of European earthworm species across northern North America has severe impacts on native ecosystems. Given the long and cold winters in that region that to date supposedly have slowed earthworm invasion, future warming is hypothesized to accelerate earthworm invasions into yet non-invaded regions. Alternatively, warming-induced reductions in soil water content (SWC) can also decrease earthworm performance. We tested these hypotheses in a field warming experiment at two sites in Minnesota, USA by sampling earthworms in closed and open canopy in three temperature treatments in 2010 and 2012. Structural equation modeling revealed that detrimental warming effects on earthworm densities and biomass could indeed be partly explained by warming-induced reductions in SWC. The direction of warming effects depended on the current average SWC: warming had neutral to positive effects at high SWC, whereas the opposite was true at low SWC. Our results suggest that warming limits the invasion of earthworms in northern North America by causing less favorable soil abiotic conditions, unless warming is accompanied by increased and temporally even distributions of rainfall sufficient to offset greater water losses from higher evapotranspiration.

  4. Historical trends and extremes in boreal Alaska river basins

    SciTech Connect

    Bennett, Katrina E.; Cannon, Alex J.; Hinzman, Larry

    2015-05-12

    Climate change will shift the frequency, intensity, duration and persistence of extreme hydroclimate events and have particularly disastrous consequences in vulnerable systems such as the warm permafrost-dominated Interior region of boreal Alaska. This work focuses on recent research results from nonparametric trends and nonstationary generalized extreme value (GEV) analyses at eight Interior Alaskan river basins for the past 50/60 years (1954/64–2013). Trends analysis of maximum and minimum streamflow indicates a strong (>+50%) and statistically significant increase in 11-day flow events during the late fall/winter and during the snowmelt period (late April/mid-May), followed by a significant decrease in the 11-day flow events during the post-snowmelt period (late May and into the summer). The April–May–June seasonal trends show significant decreases in maximum streamflow for snowmelt dominated systems (<–50%) and glacially influenced basins (–24% to –33%). Annual maximum streamflow trends indicate that most systems are experiencing declines, while minimum flow trends are largely increasing. Nonstationary GEV analysis identifies time-dependent changes in the distribution of spring extremes for snowmelt dominated and glacially dominated systems. Temperature in spring influences the glacial and high elevation snowmelt systems and winter precipitation drives changes in the snowmelt dominated basins. The Pacific Decadal Oscillation was associated with changes occurring in snowmelt dominated systems, and the Arctic Oscillation was linked to one lake dominated basin, with half of the basins exhibiting no change in response to climate variability. The paper indicates that broad scale studies examining trend and direction of change should employ multiple methods across various scales and consider regime dependent shifts to identify and understand changes in extreme streamflow within boreal forested watersheds of Alaska.

  5. Historical trends and extremes in boreal Alaska river basins

    DOE PAGES

    Bennett, Katrina E.; Cannon, Alex J.; Hinzman, Larry

    2015-05-12

    Climate change will shift the frequency, intensity, duration and persistence of extreme hydroclimate events and have particularly disastrous consequences in vulnerable systems such as the warm permafrost-dominated Interior region of boreal Alaska. This work focuses on recent research results from nonparametric trends and nonstationary generalized extreme value (GEV) analyses at eight Interior Alaskan river basins for the past 50/60 years (1954/64–2013). Trends analysis of maximum and minimum streamflow indicates a strong (>+50%) and statistically significant increase in 11-day flow events during the late fall/winter and during the snowmelt period (late April/mid-May), followed by a significant decrease in the 11-day flowmore » events during the post-snowmelt period (late May and into the summer). The April–May–June seasonal trends show significant decreases in maximum streamflow for snowmelt dominated systems (<–50%) and glacially influenced basins (–24% to –33%). Annual maximum streamflow trends indicate that most systems are experiencing declines, while minimum flow trends are largely increasing. Nonstationary GEV analysis identifies time-dependent changes in the distribution of spring extremes for snowmelt dominated and glacially dominated systems. Temperature in spring influences the glacial and high elevation snowmelt systems and winter precipitation drives changes in the snowmelt dominated basins. The Pacific Decadal Oscillation was associated with changes occurring in snowmelt dominated systems, and the Arctic Oscillation was linked to one lake dominated basin, with half of the basins exhibiting no change in response to climate variability. The paper indicates that broad scale studies examining trend and direction of change should employ multiple methods across various scales and consider regime dependent shifts to identify and understand changes in extreme streamflow within boreal forested watersheds of Alaska.« less

  6. Extreme weather event in spring 2013 delayed breeding time of Great Tit and Blue Tit.

    PubMed

    Glądalski, Michał; Bańbura, Mirosława; Kaliński, Adam; Markowski, Marcin; Skwarska, Joanna; Wawrzyniak, Jarosław; Zieliński, Piotr; Bańbura, Jerzy

    2014-12-01

    The impact of climatic changes on life cycles by re-scheduling the timing of reproduction is an important topic in studies of biodiversity. Global warming causes and will probably cause in the future not only raising temperatures but also an increasing frequency of extreme weather events. In 2013, the winter in central and north Europe ended late, with low temperatures and long-retained snow cover--this extreme weather phenomenon acted in opposition to the increasing temperature trend. In 2013, thermal conditions measured by the warmth sum in the period 15 March–15 April, a critical time for early breeding passerines, went far beyond the range of the warmth sums for at least 40 preceding years. Regardless of what was the reason for the extreme early spring 2013 and assuming that there is a potential for more atypical years because of climate change, we should look closely at every extreme phenomenon and its consequences for the phenology of organisms. In this paper, we report that the prolonged occurrence of winter conditions during the time that is crucial for Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) reproduction caused a substantial delay in the onset of egg laying in comparison with typical springs.

  7. Cyclone and Anticyclone Activities Impact Eurasian Surface Climate and Cause Extreme Cold Events ?

    NASA Astrophysics Data System (ADS)

    Lu, C.; Zhang, X.; Guan, Z.; Wang, Z.; Qin, Y.

    2014-12-01

    Extreme cold winter weather events have more frequently occurred during recent decades over the Eurasian continent, in conjunction with the rapidly warming Arctic. Although various contributing factors have been examined, including changes in the atmospheric circulation, increase in meridional span of jet stream fluctuation, and anomalous snow and sea ice forcing, it still remains unclear how internally or externally altered large-scale atmospheric dynamics has driven daily-based extreme cold events. In this study, we further investigated variability of and changes in extratropical storm tracks and anticyclones and their resultant dynamic and thermodynamic role in causing extreme cold weathers over Eurasia. The major approach employed is a modified automated cyclone and anticyclone identification and tracking algorithm. Our results reinforced our previous finding that storms have weakened and anticyclones have intensified over Eurasia during 1978/79-2011/2012 winter seasons. Corresponding to these long-term changes, anomalous high pressure occurred over the Ural area, providing fundamental dynamic setting favoring occurrence of blocking events. As a consequence, polar cold air was advected southward to the midlatitude, causing extreme cold events. Along with this dynamic process, snow cover also extended southward to reduce surface absorption of downwelling shortwave radiation and further the cooling process. Barents-Kara sea ice forcing was examined to identify underlying physical mechanisms for changes in storm tracks and anticyclone activities.

  8. Extreme rapid warming yields high functional survivals of vitrified 8-cell mouse embryos even when suspended in a half-strength vitrification solution and cooled at moderate rates to −196°C✰

    PubMed Central

    Seki, Shinsuke; Jin, Bo; Mazu, Peter

    2014-01-01

    To cryopreserve cells, it is essential to avoid intracellular ice formation during cooling and warming. One way to do so is to subject them to procedures that convert cell water into a non-crystalline glass. Current belief is that to achieve this vitrification, cells must be suspended in very high concentrations of glass-inducing solutes (i.e., ≥ 6 molal) and cooled at very high rates (i.e., >> 1,000°C/min). We report here that both these beliefs are incorrect with respect to the vitrification of 8-cell mouse embryos. In this study, precompaction 8-cell embryos were vitrified in several dilutions of EAFS10/10 using various cooling rates and warming rates. Survival was based on morphology, osmotic functionality, and on the ability to develop to expanded blastocysts. With a warming rate of 117,500°C/min, the percentages of embryos vitrified in 1×, 0.75×, and 0.5× EAFS that developed to blastocysts were 93%, 92%, and 86%, respectively. And the percentages of morphological survivors that developed to expanded blastocysts were 100%, 92%, and 97%, respectively. Even when the solute concentration of the EAFS was reduced to 33% of normal, we obtained 40% functional survival of these 8-cell embryos. PMID:24333434

  9. Decadal variability of the North Pacific Polar Front: Subsurface warming versus surface cooling

    NASA Astrophysics Data System (ADS)

    Belkin, Igor; Krishfield, Richard; Honjo, Susumu

    2002-05-01

    Over 200 hydrographic sections are used to trace the Polar Front defined as the southern boundary of the ``pure'' subarctic stratification with a pronounced, extremely cold, subsurface temperature minimum underlain by a temperature maximum. The front extends from 40°N off Japan to 57°N in the Gulf of Alaska where it retroflects and continues WSW with the Alaskan Stream. The front's decadal variability from 1977-1999 is examined along 150°E, 170°E, 175.5°E, and 180°E. At these longitudes the front is relatively stable, except for 170°E, where it shifts north-south by 400 km every 6 years. Most time series reveal a subsurface warming of ~1°C per decade, and a surface cooling, of the front. Since the subsurface temperature minimum is a remnant of winter convection, the subsurface warming signals an amelioration of the winter climate, whereas the summer climate becomes colder.

  10. Winters fuels report

    SciTech Connect

    1995-10-27

    The outlook for distillate fuel oil this winter is for increased demand and a return to normal inventory patterns, assuming a resumption of normal, cooler weather than last winter. With industrial production expected to grow slightly from last winter`s pace, overall consumption is projected to increase 3 percent from last winter, to 3.4 million barrels per day during the heating season (October 1, 1995-March 31, 1996). Much of the supply win come from stock drawdowns and refinery production. Estimates for the winter are from the Energy Information Administration`s (EIA) 4th Quarter 1995 Short-Tenn Energy Outlook (STEO) Mid-World Oil Price Case forecast. Inventories in place on September 30, 1995, of 132 million barrels were 9 percent below the unusually high year-earlier level. Inventories of high-sulfur distillate fuel oil, the principal type used for heating, were 13 percent lower than a year earlier. Supply problems are not anticipated because refinery production and the ready availability of imports should be adequate to meet demand. Residential heating off prices are expected to be somewhat higher than last winter`s, as the effects of lower crude oil prices are offset by lower distillate inventories. Heating oil is forecast to average $0.92 per gallon, the highest price since the winter of 1992-93. Diesel fuel (including tax) is predicted to be slightly higher than last year at $1.13 per gallon. This article focuses on the winter assessment for distillate fuel oil, how well last year`s STEO winter outlook compared to actual events, and expectations for the coming winter. Additional analyses include regional low-sulfur and high-sulfur distillate supply, demand, and prices, and recent trends in distillate fuel oil inventories.

  11. Dynamic characteristics of observed sudden warmings

    NASA Technical Reports Server (NTRS)

    Dartt, D. G.; Venne, D. E.

    1986-01-01

    The planetary wave dynamics of stratospheric sudden warmings in the Northern Hemisphere for a large number of observed events that occurred during winters from 1970 to 1975 and 1978 to 1981 are investigated. The analysis describes wave propagation and zonal flow interaction from the troposphere upwards to near 50 km, and in some years to near 80 km. Three primary topics are covered here: (1) the interaction of zonally propagating and quasi-stationary planetary waves during warming events; (2) planetary wave influence on zonal flow near the stratopause; and (3) planetary wave propagation to near 80 km as seen from Stratospheric and Mesospheric Sounder (SAMS) data.

  12. Communicating Certainty About Nuclear Winter

    NASA Astrophysics Data System (ADS)

    Robock, A.

    2013-12-01

    Report of the Intergovernmental Panel on Climate Change (IPCC), I inserted a paragraph pointing out that volcanic eruptions serve as an analog that supports new work on nuclear winter. This is the first time that nuclear winter has been in the IPCC report. I will tell the story of the discussions within our chapter, with review editors, and with the IPCC leadership that resulted in a box in Chapter 8 that discusses nuclear winter. We gave a briefing to John Holdren, the President's Science Advisor, about the work. Daniel Ellsberg, Fidel Castro, and Mikhail Gorbachev found out about our work, and used the results to appeal for nuclear abolition. In 2013 the work was featured at the Conference on the Humanitarian Impact of Nuclear Weapons in Oslo, Norway attended by 132 nations, and I gave a TEDx talk, I published an opinion piece on the CNN website, and I gave an invited public lecture in Nagasaki, Japan, all about the climatic consequences of nuclear war. I am now using Twitter and Facebook to communicate about nuclear winter. The threat that nuclear weapons pose to the planet is a much easier problem to solve than global warming. We need to eliminate nuclear weapons so we have the luxury of working on the global warming problem without the possibility of the existential global threat still posed by the global nuclear arsenal.

  13. Fast acclimation of freezing resistance suggests no influence of winter minimum temperature on the range limit of European beech.

    PubMed

    Lenz, Armando; Hoch, Günter; Vitasse, Yann

    2016-04-01

    Low temperature extremes drive species distribution at a global scale. Here, we assessed the acclimation potential of freezing resistance in European beech (Fagus sylvaticaL.) during winter. We specifically asked (i) how do beech populations growing in contrasting climates differ in their maximum freezing resistance, (ii) do differences result from genetic differentiation or phenotypic plasticity to preceding temperatures and (iii) is beech at risk of freezing damage in winter across its distribution range. We investigated the genetic and environmental components of freezing resistance in buds of adult beech trees from three different populations along a natural large temperature gradient in north-western Switzerland, including the site holding the cold temperature record in Switzerland. Freezing resistance of leaf primordia in buds varied significantly among populations, with LT50values (lethal temperature for 50% of samples) ranging from -25 to -40 °C, correlating with midwinter temperatures of the site of origin. Cambial meristems and the pith of shoots showed high freezing resistance in all three populations, with only a trend to lower freezing resistance at the warmer site. After hardening samples at -6 °C for 5 days, freezing resistance of leaf primordia increased in all provenances by up to 4.5 K. After additional hardening at -15 °C for 3 days, all leaf primordia were freezing resistant to -40 °C. We demonstrate that freezing resistance ofF. sylvaticahas a high ability to acclimate to temperature changes in winter, whereas the genetic differentiation of freezing resistance among populations seems negligible over this small geographic scale but large climatic gradient. In contrast to the assumption made in most of the species distribution models, we suggest that absolute minimum temperature in winter is unlikely to shape the cold range limit of beech. We conclude that the rapid acclimation of freezing resistance to winter temperatures allows

  14. Stratospheric winter climate response to ENSO in three chemistry-climate models

    NASA Astrophysics Data System (ADS)

    Fischer, A. M.; Shindell, D. T.; Winter, B.; Bourqui, M. S.; Faluvegi, G.; Rozanov, E.; Schraner, M.; Brönnimann, S.

    2008-07-01

    Three different chemistry-climate models are compared with respect to their simulation of the stratospheric response to extreme cases of ENSO. Ensemble simulations of an unusually warm ENSO event (1940-1941) compared to a very cold event (1975-1976) reveal a weaker and warmer polar vortex in the Northern Hemisphere winter. This follows from anomalously propagating waves decelerating the zonal flow and strengthening the residual mean circulation. Models are in good agreement in simulating the observed (statistically reconstructed for the case 1941) flow in the lower stratosphere over the Pacific North American region, but less so over the North Atlantic European sector with insufficient reproduction of the wave structure. Modeled column ozone is reduced in the Tropics and increased on average in the northern extra tropics in accord with the general pattern seen in observations and in line with an intensification of the Brewer-Dobson circulation.

  15. Global warming, insurance losses and financial industry

    SciTech Connect

    Low, N.C.

    1996-12-31

    Global warming causes extremely bad weather in the near term. They have already caught the attention of the insurance industry, as they suffered massive losses in the last decade. Twenty-one out of the 25 largest catastrophes in the US, mainly in the form of hurricanes have occurred in the last decade. The insurance industry has reacted by taking the risk of global warming in decisions as to pricing and underwriting decisions. But they have yet to take a more active role in regulating the factors that contributes to global warming. How global warming can impact the financial industry and the modern economy is explored. Insurance and modern financial derivatives are key to the efficient functioning of the modern economy, without which the global economy can still function but will take a giant step backward. Any risk as global warming that causes economic surprises will hamper the efficient working of the financial market and the modern economy.

  16. Storing snow for the next winter: Two case studies on the application of snow farming.

    NASA Astrophysics Data System (ADS)

    Grünewald, Thomas; Wolfsperger, Fabian

    2016-04-01

    Snow farming is the conservation of snow during the warm half-year. This means that large piles of snow are formed in spring in order to be conserved over the summer season. Well-insulating materials such as chipped wood are added as surface cover to reduce melting. The aim of snow farming is to provide a "snow guaranty" for autumn or early winter - this means that a specific amount of snow will definitively be available, independent of the weather conditions. The conserved snow can then be used as basis for the preparation of winter sports grounds such as cross-country tracks or ski runs. This helps in the organization of early winter season sport events such as World Cup races or to provide appropriate training conditions for athletes. We present a study on two snow farming projects, one in Davos (Switzerland) and one in the Martell valley of South Tyrol. At both places snow farming has been used for several years. For the summer season 2015, we monitored both snow piles in order to assess the amount of snow conserved. High resolution terrestrial laser scanning was performed to measure snow volumes of the piles at the beginning and at the end of the summer period. Results showed that only 20% to 30 % of the snow mass was lost due to ablation. This mass loss was surprisingly low considering the extremely warm and dry summer. In order to identify the most relevant drivers of snow melt we also present simulations with the sophisticated snow cover models SNOWPACK and Alpine3D. The simulations are driven by meteorological input data recorded in the vicinity of the piles and enable a detailed analysis of the relevant processes controlling the energy balance. The models can be applied to optimize settings for snow farming and to examine the suitability of new locations, configurations or cover material for future snow farming projects.

  17. Discrimination of a major stratospheric warming event in February-March 1984 from earlier minor warmings

    NASA Technical Reports Server (NTRS)

    Johnson, K. W.; Quiroz, R. S.; Gelman, M. E.

    1985-01-01

    As part of its responsibility for stratospheric monitoring, the Climate Analysis Center derives time trends of various dynamic parameters from NMC stratospheric analyses. Selected figures from this stratospheric monitoring data base are published in Climate Diagnostics Bulletin in March and October, after each hemispheric winter. During the Northern Hemisphere winter of December 1983-February 1984 several warming events may be seen in the plot of 60 deg. N zonal mean temperatures for 10 mb. Minor warmings may be noted in early December, late December, mid January and early February. A major warming with the 60 deg. N zonal mean temperatures reaching -40C is observed in late February, associated with a circulation reversal. In all of the minor warming episodes, there is a polarward movement of the Aleutian anticyclone; however, at 10 mb the North Pole remains in the cyclonic circulation of the stratospheric vortex which is not displaced far from its usual position. In the case of the later February major warming, the 10 mb circulation pattern over the North Pole is anticyclonic, and the cyclonic circulation has moved to the south and east with a considerable elongation. Cross sections of heat transport and momentum transport are not dramatically different for the minor and major warming episodes.

  18. Global Weirding? - Using Very Large Ensembles and Extreme Value Theory to assess Changes in Extreme Weather Events Today

    NASA Astrophysics Data System (ADS)

    Otto, F. E. L.; Mitchell, D.; Sippel, S.; Black, M. T.; Dittus, A. J.; Harrington, L. J.; Mohd Saleh, N. H.

    2014-12-01

    A shift in the distribution of socially-relevant climate variables such as daily minimum winter temperatures and daily precipitation extremes, has been attributed to anthropogenic climate change for various mid-latitude regions. However, while there are many process-based arguments suggesting also a change in the shape of these distributions, attribution studies demonstrating this have not currently been undertaken. Here we use a very large initial condition ensemble of ~40,000 members simulating the European winter 2013/2014 using the distributed computing infrastructure under the weather@home project. Two separate scenarios are used:1. current climate conditions, and 2. a counterfactual scenario of "world that might have been" without anthropogenic forcing. Specifically focusing on extreme events, we assess how the estimated parameters of the Generalized Extreme Value (GEV) distribution vary depending on variable-type, sampling frequency (daily, monthly, …) and geographical region. We find that the location parameter changes for most variables but, depending on the region and variables, we also find significant changes in scale and shape parameters. The very large ensemble allows, furthermore, to assess whether such findings in the fitted GEV distributions are consistent with an empirical analysis of the model data, and whether the most extreme data still follow a known underlying distribution that in a small sample size might otherwise be thought of as an out-lier. The ~40,000 member ensemble is simulated using 12 different SST patterns (1 'observed', and 11 best guesses of SSTs with no anthropogenic warming). The range in SSTs, along with the corresponding changings in the NAO and high-latitude blocking inform on the dynamics governing some of these extreme events. While strong tele-connection patterns are not found in this particular experiment, the high number of simulated extreme events allows for a more thorough analysis of the dynamics than has been

  19. Recent trends of extreme temperature indices for the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Fonseca, D.; Carvalho, M. J.; Marta-Almeida, M.; Melo-Gonçalves, P.; Rocha, A.

    2016-08-01

    Climate change and extreme climate events have a significant impact on societies and ecosystems. As a result, climate change projections, especially related with extreme temperature events, have gained increasing importance due to their impacts on the well-being of the population and ecosystems. However, most studies in the field are based on coarse global climate models (GCMs). In this study, we perform a high resolution downscaling simulation to evaluate recent trends of extreme temperature indices. The model used was Weather Research and Forecast (WRF) forced by MPI-ESM-LR, which has been shown to be one of the more robust models to simulate European climate. The domain used in the simulations includes the Iberian Peninsula and the simulation covers the 1986-2005 period (i.e. recent past). In order to study extreme temperature events, trends were computed using the Theil-Sen method for a set of temperature indexes defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). For this, daily values of minimum and maximum temperatures were used. The trends of the indexes were computed for annual and seasonal values and the Mann-Kendall Trend test was used to evaluate their statistical significance. In order to validate the results, a second simulation, in which WRF was forced by ERA-Interim, was performed. The results suggest an increase in the number of warm days and warm nights, especially during summer and negative trends for cold nights and cold days for the summer and spring. For the winter, contrary to the expected, the results suggest an increase in cold days and cold nights (warming hiatus). This behavior is supported by the WRF simulation forced by ERA-Interim for the autumn days, pointing to an extension of the warming hiatus phenomenon to the remaining seasons. These results should be used with caution since the period used to calculate the trends may not be long enough for this purpose. However, the general sign of trends are similar for

  20. Climatic changes and associated impacts in the Mediterranean resulting from a 2 °C global warming

    NASA Astrophysics Data System (ADS)

    Giannakopoulos, C.; Le Sager, P.; Bindi, M.; Moriondo, M.; Kostopoulou, E.; Goodess, C. M.

    2009-08-01

    Climatic changes over the Mediterranean basin in 2031-2060, when a 2 °C global warming is most likely to occur, are investigated with the HadCM3 global circulation model and their impacts on human activities and natural ecosystem are assessed. Precipitation and surface temperature changes are examined through mean and extreme values analysis, under the A2 and B2 emission scenarios. Confidence in results is obtained via bootstrapping. Over the land areas, the warming is larger than the global average. The rate of warming is found to be around 2 °C in spring and winter, while it reaches 4 °C in summer. An additional month of summer days is expected, along with 2-4 weeks of tropical nights. Increase in heatwave days and decrease in frost nights are expected to be a month inland. In the northern part of the basin the widespread drop in summer rainfall is partially compensated by a winter precipitation increase. One to 3 weeks of additional dry days lead to a dry season lengthened by a week and shifted toward spring in the south of France and inland Algeria, and autumn elsewhere. In central Mediterranean droughts are extended by a month, starting a week earlier and ending 3 weeks later. The impacts of these climatic changes on human activities such as agriculture, energy, tourism and natural ecosystems (forest fires) are also assessed. Regarding agriculture, crops whose growing cycle occurs mostly in autumn and winter show no changes or even an increase in yield. In contrast, summer crops show a remarkable decrease of yield. This different pattern is attributed to a lengthier drought period during summer and to an increased rainfall in winter and autumn. Regarding forest fire risk, an additional month of risk is expected over a great part of the basin. Energy demand levels are expected to fall significantly during a warmer winter period inland, whereas they seem to substantially increase nearly everywhere during summer. Extremely high summer temperatures in the

  1. Effect of simulated fall heat waves on cold hardiness and winter survival of hemlock looper, Lambdina fiscellaria (Lepidoptera: Geometridae).

    PubMed

    Vallières, Rosemarie; Rochefort, Sophie; Berthiaume, Richard; Hébert, Christian; Bauce, Éric

    2015-02-01

    The hemlock looper (Lambdina fiscellaria) is an important pest of eastern Canadian forests. The ongoing climate warming could modify the seasonal ecology of this univoltine species that lays eggs at the end of summer and overwinters at this stage. Indeed, the increase in frequency and intensity of extreme climatic events such as fall heat waves could interfere with the winter metabolism of the hemlock looper. Moreover, the host plant quality, which influences the quantity of insect energetic reserves, the geographic origin of populations and the conditions prevailing during the cold acclimation period, could cause various responses of this pest to climate warming. The main objective of this study is to determine the impact of these factors on hemlock looper winter biology. In October 2010, hemlock looper eggs initially collected from two geographic areas in the province of Québec, and from parents reared on two host plants, were exposed to fall heat waves of different intensities during 5 consecutive days. Supercooling points and cryoprotectant levels were measured on eggs on four different dates in 2010-2011 and survival rate was measured in April 2011. Our results show that hemlock looper eggs have a very low supercooling point and high levels of trehalose, glucose and mannitol in September and November. However, there is no clear relationship between the concentration of these compounds and the decrease in supercooling points. Contents in trehalose, glucose and mannitol were significantly influenced by fall heat waves and by the origin of the population. Winter survival of eggs from the temperate population was negatively affected by strong heat waves while the boreal population was not affected. This study suggests that the metabolism and winter survival of temperate hemlock looper populations in Québec will be more affected by fall heat waves that will increase in frequency due to climate change, than boreal populations.

  2. Winter Art Education Project

    ERIC Educational Resources Information Center

    Jokela, Timo

    2007-01-01

    The purpose of this article is to describe how the Department of Art Education at the University of Lapland in Finland has developed winter art as a method of environmental and community-based art education. I will focus on the Snow Show Winter Art Education Project, a training project funded by the European Union and the State Provincial Office…

  3. Evaluation of large-scale meteorological patterns associated with temperature extremes in the NARCCAP regional climate model simulations

    NASA Astrophysics Data System (ADS)

    Loikith, Paul C.; Waliser, Duane E.; Lee, Huikyo; Neelin, J. David; Lintner, Benjamin R.; McGinnis, Seth; Mearns, Linda O.; Kim, Jinwon

    2015-12-01

    Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of well-simulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts.

  4. Solar aquaculture: A wintering technique for parent prawns

    SciTech Connect

    Cao Jin Long

    1994-09-01

    A new method of providing the warm water needed for parent prawn wintering using solar energy is described. Using solar energy for prawn wintering involves heat collection, heat storage and temperature maintenance. The system designed provides sufficient energy for the safe wintering of prawns with suitable water temperatures. The temperature control facilities consist of three parts: a salt gradient solar pond, a shallow solar pond and a plastic house. The technique involves use of a shallow solar pond for collection and storage of heat. The average temperature in the wintering pond plastic house was 11 degrees C and the minimum temperature in January was 5.4 degrees C. This system allowed the wintering process to be conducted using solar energy alone and may extend aquaculture to higher latitudes. The ratio of net profit with the solar energy system over investment is 1.5 which makes it economically viable.

  5. Climate warming could increase recruitment success in glacier foreland plants

    PubMed Central

    Mondoni, Andrea; Pedrini, Simone; Bernareggi, Giulietta; Rossi, Graziano; Abeli, Thomas; Probert, Robin J.; Ghitti, Michele; Bonomi, Costantino; Orsenigo, Simone

    2015-01-01

    Background and Aims Glacier foreland plants are highly threatened by global warming. Regeneration from seeds on deglaciated terrain will be crucial for successful migration and survival of these species, and hence a better understanding of the impacts of climate change on seedling recruitment is urgently needed to predict future plant persistence in these environments. This study presents the first field evidence of the impact of climate change on recruitment success of glacier foreland plants. Methods Seeds of eight foreland species were sown on a foreland site at 2500 m a.s.l., and at a site 400 m lower in altitude to simulate a 2·7 °C increase in mean annual temperature. Soil from the site of origin was used to reproduce the natural germination substrate. Recruitment success, temperature and water potential were monitored for 2 years. The response of seed germination to warming was further investigated in the laboratory. Key Results At the glacier foreland site, seedling emergence was low (0 to approx. 40 %) and occurred in summer in all species after seeds had experienced autumn and winter seasons. However, at the warmer site there was a shift from summer to autumn emergence in two species and a significant increase of summer emergence (13–35 % higher) in all species except two. Survival and establishment was possible for 60–75 % of autumn-emerged seedlings and was generally greater under warmer conditions. Early snowmelt in spring caused the main ecological factors enhancing the recruitment success. Conclusions The results suggest that warming will influence the recruitment of glacier foreland species primarily via the extension of the snow-free period in spring, which increases seedling establishment and results in a greater resistance to summer drought and winter extremes. The changes in recruitment success observed here imply that range shifts or changes in abundance are possible in a future warmer climate, but overall success may be dependent

  6. Winter thunderstorms in central Europe in the past and the present

    NASA Astrophysics Data System (ADS)

    Munzar, Jan; Franc, Marek

    Thunderstorms in the territories of the Czech Republic and neighbouring countries are almost exclusively the only phenomena occurring in the warm season. In the cold half of the year, from October to March, an average incidence of thunderstorms is only 2%, with the least occurrence being recorded in January. Yet, winter thunderstorms are dangerous particularly for air traffic because during them, the cloud base is rapidly falling down and visibility is suddenly worsening due to heavy snowfall. Notwithstanding these facts, the issue of their occurrence in the central European space has been paid little attention so far. Long years of study into historical weather extremes in the territory of the Czech Republic revealed over 10 chronicle entries on the occurrence of winter thunderstorms in the period between November and February from the 16th to the beginning of the 20th centuries. The irregular phenomenon was even devoted three occasional prints in central Europe in the second half of the 16th century, two of which were issued in Germany. Fires caused by winter thunderstorms were no sporadic cases. The occurrence of thunderstorms in winter was apparently associated with the passage of pronounced cold fronts. This can be documented on cases from the end of December 1555 when heavy thunderstorms and consequent fires were recorded within a short period of time in Holland, Germany and in Czech lands. It is assumed that the situation in 1627 was similar when a winter thunderstorm was recorded in Prague and in Holešov, southeastern Moravia on 28 December. In February 1581, a thunderstorm in Prague became one of three unusual events publicized by the local occasional newspaper. The beginning of modern studies into winter thunderstorms dates back to the 1960s with the use of lightning flash counters and later also with the use of systems for large-scale lightning flash detection and localization. However, more comprehensive meteorological and climatological assessments of

  7. Global warming, bad weather, insurance losses and the global economy

    SciTech Connect

    Low, N.C.; Shen, S.

    1996-09-01

    Global warming causes extremely bad weather in the near term. The impact on the insurance industry is described. Why global warming in the near term causes very bad weather is explained. The continuing trend of very bad weather and the future impact on the insurance industry is explored. How very bad weather can affect the global financial market is explained. Taking a historical view of the development of the modern economy, the authors describe in the near term the impact of global warming on the global economy. The long term impact of global warming on the global economy and the human race is explored. Opportunities presented by global warming are described.

  8. Large Scale Influences on Drought and Extreme Precipitation Events in the United States

    NASA Astrophysics Data System (ADS)

    Collow, A.; Bosilovich, M. G.; Koster, R. D.; Eichmann, A.

    2015-12-01

    Observations indicate that extreme weather events are increasing and it is likely that this trend will continue through the 21st century. However, there is uncertainty and disagreement in recent literature regarding the mechanisms by which extreme temperature and precipitation events are increasing, including the suggestion that enhanced Arctic warming has resulted in an increase in blocking events and a more meridional flow. A steady gradual increase in heavy precipitation events has been observed in the Midwestern and Northeastern United States, while the Southwestern United States, particularly California, has experienced suppressed precipitation and an increase in consecutive dry days over the past few years. The frequency, intensity, and duration of heavy precipitation events in the Midwestern United States and Northeastern United States, as well as drought in the Southwestern United States are examined using the Modern Era Retrospective Analysis for Research and Applications Version-2 (MERRA-2). Indices developed by the Expert Team on Climate Change Detection and Indices representing drought and heavy precipitation events have been calculated using the MERRA-2 dataset for the period of 1980 through 2014. Trends in these indices are analyzed and the indices are compared to large scale circulations and climate modes using a composite and statistical linkages approach. Statistically significant correlations are present in the summer months between heavy precipitation events and meridional flow despite the lack of enhanced Arctic warming, contradicting the suggested mechanisms. Weaker, though still significant, correlations are observed in the winter months when the Arctic is warming more rapidly than the Midlatitudes.

  9. Rapid warming of Large Marine Ecosystems

    NASA Astrophysics Data System (ADS)

    Belkin, Igor M.

    2009-04-01

    The need to understand local effects of global climate change is most urgent in the Large Marine Ecosystems (LMEs) since marine ecosystem-based management requires information on the LME scale. Reported here is a study of sea surface temperature (SST) change in the World Ocean LMEs in 1957-2006 that revealed strong regional variations in the rate of SST change. The rapid warming in 1982-2006 was confined to the Subarctic Gyre, European Seas, and East Asian Seas. These LMEs warmed at rates 2-4 times the global mean rate. The most rapid warming was observed in the land-locked or semi-enclosed European and East Asian Seas (Baltic Sea, North Sea, Black Sea, Japan Sea/East Sea, and East China Sea) and also over the Newfoundland-Labrador Shelf. The Indian Ocean LMEs’ warming was slow, while two major upwelling areas - California and Humboldt Currents - experienced a slight cooling. The Subarctic Gyre warming was likely caused by natural variability related to the North Atlantic Oscillation. The extremely rapid surface warming in the enclosed and semi-enclosed European and East Asian Seas surrounded by major industrial/population agglomerations may have resulted from the observed terrestrial warming directly affecting the adjacent coastal seas. Regions of freshwater influence in the European and East Asian Seas seem to play a special role in modulating and exacerbating global warming effects on the regional scale.

  10. Urban climate effects on extreme temperatures in Madison, Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Schatz, Jason; Kucharik, Christopher J.

    2015-09-01

    As climate change increases the frequency and intensity of extreme heat, cities and their urban heat island (UHI) effects are growing, as are the urban populations encountering them. These mutually reinforcing trends present a growing risk for urban populations. However, we have limited understanding of urban climates during extreme temperature episodes, when additional heat from the UHI may be most consequential. We observed a historically hot summer and historically cold winter using an array of up to 150 temperature and relative humidity sensors in and around Madison, Wisconsin, an urban area of population 402 000 surrounded by lakes and a rural landscape of agriculture, forests, wetlands, and grasslands. In the summer of 2012 (third hottest since 1869), Madison’s urban areas experienced up to twice as many hours ⩾32.2 °C (90 °F), mean July TMAX up to 1.8 °C higher, and mean July TMIN up to 5.3 °C higher than rural areas. During a record setting heat wave, dense urban areas spent over four consecutive nights above the National Weather Service nighttime heat stress threshold of 26.7 °C (80 °F), while rural areas fell below 26.7 °C nearly every night. In the winter of 2013-14 (coldest in 35 years), Madison’s most densely built urban areas experienced up to 40% fewer hours ⩽-17.8 °C (0 °F), mean January TMAX up to 1 °C higher, and mean January TMIN up to 3 °C higher than rural areas. Spatially, the UHI tended to be most intense in areas with higher population densities. Temporally, both daytime and nighttime UHIs tended to be slightly more intense during more-extreme heat days compared to average summer days. These results help us understand the climates for which cities must prepare in a warming, urbanizing world.

  11. Coastal Greenland air temperature extremes 1890-2010

    NASA Astrophysics Data System (ADS)

    Mernild, Sebastian H.; Hanna, Edward; Cappelen, John

    2013-04-01

    We use observed air temperature data series from fourteen meteorological stations in coastal Greenland (located all around the Greenland Ice Sheet (GrIS)) for 1960-2010, where long-term records for five of the stations extend back to 1890, to illustrate the annual and monthly temporal and spatial distribution of temperature extremes. We find that the 2000s (2001-2010) had the highest number of mean annual air temperature (MAAT) warm extremes, and the 1890s (1891-1900) the highest number of cold extremes. For the 2000s the number of warm extremes was significantly higher by around 50% than the number in the 1940s (the Early Twentieth Century Warm Period): the decade with the second highest occurrence of MAAT warm extremes. Since 1960, based on MAAT the number of cold extremes has decreased on the decadal timescale, while warm extremes have increased leading to a higher occurrence of extremes (cold plus warm extremes): an almost similar pattern occurred on mean monthly and on monthly mean daily maximum and minimum scales. Further, a division of Greenland into east and west sectors shows that the occurrence of cold (warm) extremes was more pronounced in the East than in the West in the 1960s and 1970s (mid-1980s to the 2000s).

  12. Tropical Pacific impacts on cooling North American winters

    NASA Astrophysics Data System (ADS)

    Sigmond, Michael; Fyfe, John C.

    2016-10-01

    The North American continent generally experienced a cooling trend in winter over the early 2000s. This cooling trend represented a significant deviation from expected anthropogenic warming and so requires explanation. Previous studies indicate that climate variations in the tropical Pacific contributed to many mid-latitude climate variations over the early twenty-first century. Here we show using large ensembles of fully coupled, partially coupled and uncoupled model simulations that in northwest North America the winter cooling was primarily a remote response to climate fluctuations in the tropical Pacific. By contrast, in central North America the winter cooling appears to have resulted from a relatively rare fluctuation in mid-latitude circulation that was unrelated to the tropical Pacific. Our results highlight how decadal climate signals--both remote and local in origin--can together offset anthropogenic warming to produce continental-scale cooling.

  13. Warm Up with Skill.

    ERIC Educational Resources Information Center

    Hoyle, R. J.; Smith, Robert F.

    1989-01-01

    Too little time is often spent on warm-up activities in the school or recreation class. Warm-ups are often perfunctory and unimaginative. Several suggestions are made for warm-up activities that incorporate both previously learned and new skills, while preparing the body for more vigorous activity. (IAH)

  14. Geo-spatial analysis of temporal trends of temperature and its extremes over India using daily gridded (1°×1°) temperature data of 1969-2005

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Seshasai, M. V. R.; Rao, S. V. C. Kameswara; Dadhwal, V. K.

    2016-07-01

    Daily gridded (1°×1°) temperature data (1969-2005) were used to detect spatial patterns of temporal trends of maximum and minimum temperature (monthly and seasonal), growing degree days (GDDs) over the crop-growing season (kharif, rabi, and zaid) and annual frequencies of temperature extremes over India. The direction and magnitude of trends, at each grid level, were estimated using the Mann-Kendall statistics (α = 0.05) and further assessed at the homogeneous temperature regions using a field significance test (α=0.05). General warming trends were observed over India with considerable variations in direction and magnitude over space and time. The spatial extent and the magnitude of the increasing trends of minimum temperature (0.02-0.04 °C year-1) were found to be higher than that of maximum temperature (0.01-0.02 °C year-1) during winter and pre-monsoon seasons. Significant negative trends of minimum temperature were found over eastern India during the monsoon months. Such trends were also observed for the maximum temperature over northern and eastern parts, particularly in the winter month of January. The general warming patterns also changed the thermal environment of the crop-growing season causing significant increase in GDDs during kharif and rabi seasons across India. The warming climate has also caused significant increase in occurrences of hot extremes such as hot days and hot nights, and significant decrease in cold extremes such as cold days and cold nights.

  15. Impacts of extreme precipitation and seasonal changes in precipitation on plants

    NASA Astrophysics Data System (ADS)

    Zeppel, M. J. B.; Wilks, J.; Lewis, J. D.

    2013-10-01

    The hydrological cycle is predicted to become more intense in future climates, with both larger precipitation events and longer times between events. Redistribution of precipitation may occur both within and across seasons, and the resulting wide fluctuations in soil water content may dramatically affect plants. Though these responses remain poorly understood, recent research in this emerging field suggests the effects of redistributed precipitation may differ from predictions based on previous drought studies. We review available studies on both extreme precipitation (redistribution within seasons) and seasonal changes in precipitation (redistribution across seasons) on grasslands and forests. Extreme precipitation differentially affected Aboveground Net Primary Productivity (ANPP), depending on whether extreme precipitation led to increased or decreased soil water content (SWC), which differed based on the current precipitation at the site. Specifically, studies to date reported that extreme precipitation decreased ANPP in mesic sites, but, conversely, increased ANPP in xeric sites, suggesting that plant available water is a key factor driving responses to extreme precipitation. Similarly, the effects of seasonal changes in precipitation on ANPP, phenology, and leaf and fruit development varied with the effect on SWC. Reductions in spring or summer generally had negative effects on plants, associated with reduced SWC, while subsequent reductions in autumn or winter had little effect on SWC or plants. Similarly, increased summer precipitation had a more dramatic impact on plants than winter increases in precipitation. The patterns of response suggest xeric biomes may respond positively to extreme precipitation, while comparatively mesic biomes may be more likely to be negatively affected. And, seasonal changes in precipitation during warm or dry seasons may have larger effects than changes during cool or wet seasons. Accordingly, responses to redistributed

  16. The Winter Is Past.

    ERIC Educational Resources Information Center

    Busch, Phyllis S.

    1985-01-01

    Teacher, writer, and naturalist Phyllis S. Busch takes the reader on an early evening woodland walk in March, describing the many changes in plants and animals that are perceptible by sight, smell, and sound as nature awakens from winter. (NEC)

  17. Permafrost degradation stimulates carbon loss from experimentally warmed tundra.

    PubMed

    Natali, Susan M; Schuur, Edward A G; Webb, Elizabeth E; Pries, Caitlin E Hicks; Crummer, Kathryn G

    2014-03-01

    A large pool of organic carbon (C) has been accumulating in the Arctic for thousands of years because cold and waterlogged conditions have protected soil organic material from microbial decomposition. As the climate warms this vast and frozen C pool is at risk of being thawed, decomposed, and released to the atmosphere as greenhouse gasses. At the same time, some C losses may be offset by warming-mediated increases in plant productivity. Plant and microbial responses to warming ultimately determine net C exchange from ecosystems, but the timing and magnitude of these responses remain uncertain. Here we show that experimental warming and permafrost (ground that remains below 0 degrees C for two or more consecutive years) degradation led to a two-fold increase in net ecosystem C uptake during the growing season. However, warming also enhanced winter respiration, which entirely offset growing-season C gains. Winter C losses may be even higher in response to actual climate warming than to our experimental manipulations, and, in that scenario, could be expected to more than double overall net C losses from tundra to the atmosphere. Our results highlight the importance of winter processes in determining whether tundra acts as a C source or sink, and demonstrate the potential magnitude of C release from the permafrost zone that might be expected in a warmer climate.

  18. International scientists on nuclear winter

    SciTech Connect

    Malone, T.F.

    1985-12-01

    A report by the International Council of Scientific Unions (ICSU) leads new support to the warning of extreme climatic disruptions that would follow a nuclear war. The two-volume report does not deal explicitly with public policy questions, but focuses on scientific knowledge of physical effects and biological responses. The author reviews studies made since the warning of a nuclear winter began in 1982, and evaluates the new report. He finds the message of the report to be a clear warning that a major nuclear war would threaten the entire world. He hopes it will be a catalyst to world opinion in the same way that the public responded to the incident of radioactive fallout striking a Japanese fishing vessel in 1954.

  19. Local adaptations to frost in marginal and central populations of the dominant forest tree Fagus sylvatica L. as affected by temperature and extreme drought in common garden experiments

    PubMed Central

    Kreyling, Juergen; Buhk, Constanze; Backhaus, Sabrina; Hallinger, Martin; Huber, Gerhard; Huber, Lukas; Jentsch, Anke; Konnert, Monika; Thiel, Daniel; Wilmking, Martin; Beierkuhnlein, Carl

    2014-01-01

    Local adaptations to environmental conditions are of high ecological importance as they determine distribution ranges and likely affect species responses to climate change. Increased environmental stress (warming, extreme drought) due to climate change in combination with decreased genetic mixing due to isolation may lead to stronger local adaptations of geographically marginal than central populations. We experimentally observed local adaptations of three marginal and four central populations of Fagus sylvaticaL., the dominant native forest tree, to frost over winter and in spring (late frost). We determined frost hardiness of buds and roots by the relative electrolyte leakage in two common garden experiments. The experiment at the cold site included a continuous warming treatment; the experiment at the warm site included a preceding summer drought manipulation. In both experiments, we found evidence for local adaptation to frost, with stronger signs of local adaptation in marginal populations. Winter frost killed many of the potted individuals at the cold site, with higher survival in the warming treatment and in those populations originating from colder environments. However, we found no difference in winter frost tolerance of buds among populations, implying that bud survival was not the main cue for mortality. Bud late frost tolerance in April differed between populations at the warm site, mainly because of phenological differences in bud break. Increased spring frost tolerance of plants which had experienced drought stress in the preceding summer could also be explained by shifts in phenology. Stronger local adaptations to climate in geographically marginal than central populations imply the potential for adaptation to climate at range edges. In times of climate change, however, it needs to be tested whether locally adapted populations at range margins can successfully adapt further to changing conditions. PMID:25035801

  20. Local adaptations to frost in marginal and central populations of the dominant forest tree Fagus sylvatica L. as affected by temperature and extreme drought in common garden experiments.

    PubMed

    Kreyling, Juergen; Buhk, Constanze; Backhaus, Sabrina; Hallinger, Martin; Huber, Gerhard; Huber, Lukas; Jentsch, Anke; Konnert, Monika; Thiel, Daniel; Wilmking, Martin; Beierkuhnlein, Carl

    2014-03-01

    Local adaptations to environmental conditions are of high ecological importance as they determine distribution ranges and likely affect species responses to climate change. Increased environmental stress (warming, extreme drought) due to climate change in combination with decreased genetic mixing due to isolation may lead to stronger local adaptations of geographically marginal than central populations. We experimentally observed local adaptations of three marginal and four central populations of Fagus sylvaticaL., the dominant native forest tree, to frost over winter and in spring (late frost). We determined frost hardiness of buds and roots by the relative electrolyte leakage in two common garden experiments. The experiment at the cold site included a continuous warming treatment; the experiment at the warm site included a preceding summer drought manipulation. In both experiments, we found evidence for local adaptation to frost, with stronger signs of local adaptation in marginal populations. Winter frost killed many of the potted individuals at the cold site, with higher survival in the warming treatment and in those populations originating from colder environments. However, we found no difference in winter frost tolerance of buds among populations, implying that bud survival was not the main cue for mortality. Bud late frost tolerance in April differed between populations at the warm site, mainly because of phenological differences in bud break. Increased spring frost tolerance of plants which had experienced drought stress in the preceding summer could also be explained by shifts in phenology. Stronger local adaptations to climate in geographically marginal than central populations imply the potential for adaptation to climate at range edges. In times of climate change, however, it needs to be tested whether locally adapted populations at range margins can successfully adapt further to changing conditions.

  1. Winter Weather: Indoor Safety

    MedlinePlus

    ... cover windows with blankets at night. Monitor Body Temperature Infants less than one year old should never ... infants and try to maintain a warm indoor temperature. If the temperature cannot be maintained, make temporary ...

  2. Investigating NARCCAP Precipitation Extremes via Bivariate Extreme Value Theory (Invited)

    NASA Astrophysics Data System (ADS)

    Weller, G. B.; Cooley, D. S.; Sain, S. R.; Bukovsky, M. S.; Mearns, L. O.

    2013-12-01

    We introduce methodology from statistical extreme value theory to examine the ability of reanalysis-drive regional climate models to simulate past daily precipitation extremes. Going beyond a comparison of summary statistics such as 20-year return values, we study whether the most extreme precipitation events produced by climate model simulations exhibit correspondence to the most extreme events seen in observational records. The extent of this correspondence is formulated via the statistical concept of tail dependence. We examine several case studies of extreme precipitation events simulated by the six models of the North American Regional Climate Change Assessment Program (NARCCAP) driven by NCEP reanalysis. It is found that the NARCCAP models generally reproduce daily winter precipitation extremes along the Pacific coast quite well; in contrast, simulation of past daily summer precipitation extremes in a central US region is poor. Some differences in the strength of extremal correspondence are seen in the central region between models which employ spectral nudging and those which do not. We demonstrate how these techniques may be used to draw a link between extreme precipitation events and large-scale atmospheric drivers, as well as to downscale extreme precipitation simulated by a future run of a regional climate model. Specifically, we examine potential future changes in the nature of extreme precipitation along the Pacific coast produced by the pineapple express (PE) phenomenon. A link between extreme precipitation events and a "PE Index" derived from North Pacific sea-surface pressure fields is found. This link is used to study PE-influenced extreme precipitation produced by a future-scenario climate model run.

  3. Six-month lead downscaling prediction of winter-spring drought in South Korea based on multi-model ensemble

    NASA Astrophysics Data System (ADS)

    Sohn, Soo-Jin; Ahn, Joong-Bae; Tam, Chi-Yung

    2013-04-01

    Given the changing climate, advance information on hydrological extremes such as droughts will help in planning for disaster mitigation and facilitate better decision making for water availability management. A deficit of precipitation for long-term time scales beyond 6 months has impacts on the hydrological sectors such as ground water, streamflow, and reservoir storage. The potential of using a dynamical-statistical method for long-lead drought prediction was investigated. In particular, the APEC Climate Center (APCC) 1-Tier multi-model ensemble (MME) was downscaled for predicting the standardized precipitation evapotranspiration index (SPEI) over 60 stations in South Korea. SPEI depends on both of precipitation and temperature, and can incorporate the impact of global warming on the balance between precipitation and evapotranspiration. It was found that 1-Tier MME has difficulties in capturing the local temperature and rainfall variations over extratropical land areas, and has no skill in predicting SPEI during boreal winter and spring. On the other hand, temperature and precipitation predictions were substantially improved in the downscaled MME (DMME). In conjunction with variance inflation, DMME can give reasonably skillful six-month-lead forecasts of SPEI for the winter-to-spring period. The results could potentially improve hydrological extreme predictions using meteorological forecasts for policymaker and stakeholders in water management sector for better climate adaption.

  4. Applying Poultry Litter in the Fall to Fertilize Corn May not be Advisable Under Warm Climate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Row crop farmers prefer to apply poultry litter in the fall or winter but whether this practice is safe environmentally and effective for production in regions with warm fall and winter months is not well researched and documented. Research in Mississippi tested the effectiveness of fall- versus spr...

  5. Persistent cold air outbreaks over North America in a warming climate

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Leung, L. Ruby; Lu, Jian; Masato, Giacomo

    2015-04-01

    This study examines future changes of cold air outbreaks (CAOs) using a multi-model ensemble of global climate simulations from the Coupled Model Intercomparison Project Phase 5 and high resolution regional climate simulations. Overall, climate models agree on a dip in CAO duration across North America, but the percentage change is consistently smaller from western Canada to the upper mid-western US with historically more frequent CAO. By decomposing the changes of the probability density function of daily surface temperature into changes due to mean warming and changes in standard deviation (std) and skewness/higher order moments, the contributions of each factor to CAO changes are quantified. Results show that CAO changes can be explained largely by the mean warming, but the decrease in temperature std contributes to about 20% reduction of CAO from Alaska to northeastern US and eastern Canada possibly due to the Arctic amplification and weakening of storm track. A thermodynamical modulation of the skewness called the ‘0 °C mode’ effect is found to operate prominently along the 0 °C isotherm hemispherically and reduce CAO in western and northeastern US with winter snow cover by up to 10%. This effect also produces a manifold increase in CAO events over the Arctic sea ice. An increased frequency in atmospheric blocking also contributes to increases in CAO duration over Alaska and the Arctic region. Regional simulations revealed more contributions of existing snowpack to CAO in the near future over the Rocky Mountain, southwestern US, and Great Lakes areas through surface albedo effects. Overall, the multi-model projections emphasize that cold extremes do not completely disappear in a warming climate. Concomitant with the relatively smaller reduction in CAO events in northwestern US, the top five most extreme CAO events may still occur, and wind chill will continue to have societal impacts in that region.

  6. Extreme conditions over Europe and North America: role of the Atlantic Multidecadal Variability

    NASA Astrophysics Data System (ADS)

    Ruprich-Robert, Yohan; Msadek, Rym; Delworth, Tom

    2016-04-01

    The Atlantic Multidecadal Variability (AMV) is the result and possibly the source of marked modulations of the climate over many areas of the globe. For instance, the relatively warm and dry climate of North America throughout the 30-yr interval of 1931-60, during which the Dust Bowl and the 1950's drought occurred, has been linked to the concomitant warm phase of the AMV. During this period relative warm and wet conditions prevailed over Europe. After 1960, the Atlantic began to cool, and for almost three decades the North American climate turned wetter and cooler whereas Europe experienced cooler and dryer conditions. However, the shortness of the historical observations compared to the AMV period suggested by longer proxy (~60-80yr) does not allow to firmly conclude on the causal effect of the AMV. We use a model approach to isolate the causal role of the AMV on the occurrence of extreme events over Europe and North America. We present experiments based on two GFDL global climate models, a low resolution version, CM2.1 and a higher resolution model for the atmospheric component, FLOR. In both model experiments sea surface temperatures in the North Atlantic sector are restored to the observed AMV pattern, while the other basins are left fully coupled. In order to explore and robustly isolate the AMV impacts on extreme events, we use large ensemble simulations (100 members for CM2.1 and 50 for FLOR) that we run for 20 years. We find that a positive phase of the AMV increases the frequency of occurrence of drought over North America and of extremely cold/warm conditions over Northern/Central Europe during winter/summer. Interestingly, we find that the AMV impacts on these extreme conditions are modulated by the Pacific response to the AMV itself. Members that develop a weak Pacific response show more extreme events over Europe whereas those that develop a strong Pacific response show more extreme events over North America.

  7. Recent warming at Summit, Greenland: Global context and implications

    NASA Astrophysics Data System (ADS)

    McGrath, Daniel; Colgan, William; Bayou, Nicolas; Muto, Atsuhiro; Steffen, Konrad

    2013-05-01

    at Summit, Greenland suggest that the annual mean near-surface air temperature increased at 0.09 ± 0.01°C/a over the 1982-2011 climatology period. This rate of warming, six times the global average, places Summit in the 99th percentile of all globally observed warming trends over this period. The rate of warming at Summit is increasing over time. During the instrumental period (1987-2011), warming has been greatest in the winter season, although the implications of summer warming are more acute. The annual maximum elevation of the equilibrium line and dry snow line has risen at 44 and 35 m/a over the past 15 and 18 years, respectively. Extrapolation of this observed trend now suggests, with 95% confidence intervals, that the dry snow facies of the Greenland Ice Sheet will inevitably transition to percolation facies. There is a 50% probability of this transition occurring by 2025.

  8. Global Warming and Neotropical Rainforests: A Historical Perspective

    NASA Astrophysics Data System (ADS)

    Jaramillo, Carlos; Cárdenas, Andrés

    2013-05-01

    There is concern over the future of the tropical rainforest (TRF) in the face of global warming. Will TRFs collapse? The fossil record can inform us about that. Our compilation of 5,998 empirical estimates of temperature over the past 120 Ma indicates that tropics have warmed as much as 7°C during both the mid-Cretaceous and the Paleogene. We analyzed the paleobotanical record of South America during the Paleogene and found that the TRF did not expand toward temperate latitudes during global warm events, even though temperatures were appropriate for doing so, suggesting that solar insolation can be a constraint on the distribution of the tropical biome. Rather, a novel biome, adapted to temperate latitudes with warm winters, developed south of the tropical zone. The TRF did not collapse during past warmings; on the contrary, its diversity increased. The increase in temperature seems to be a major driver in promoting diversity.

  9. Warming modifies trophic cascades and eutrophication in experimental freshwater communities.

    PubMed

    Kratina, Pavel; Greig, Hamish S; Thompson, Patrick L; Carvalho-Pereira, Ticiana S A; Shurin, Jonathan B

    2012-06-01

    Climate warming is occurring in concert with other anthropogenic changes to ecosystems. However, it is unknown whether and how warming alters the importance of top-down vs. bottom-up control over community productivity and variability. We performed a 16-month factorial experimental manipulation of warming, nutrient enrichment, and predator presence in replicated freshwater pond mesocosms to test their independent and interactive impacts. Warming strengthened trophic cascades from fish to primary producers, and it decreased the impact of eutrophication on the mean and temporal variation of phytoplankton biomass. These impacts varied seasonally, with higher temperatures leading to stronger trophic cascades in winter and weaker algae blooms under eutrophication in summer. Our results suggest that higher temperatures may shift the control of primary production in freshwater ponds toward stronger top-down and weaker bottom-up effects. The dampened temporal variability of algal biomass under eutrophication at higher temperatures suggests that warming may stabilize some ecosystem processes.

  10. Changes in Concurrent Precipitation and Temperature Extremes

    DOE PAGES

    Hao, Zengchao; AghaKouchak, Amir; Phillips, Thomas J.

    2013-08-01

    While numerous studies have addressed changes in climate extremes, analyses of concurrence of climate extremes are scarce, and climate change effects on joint extremes are rarely considered. This study assesses the occurrence of joint (concurrent) monthly continental precipitation and temperature extremes in Climate Research Unit (CRU) and University of Delaware (UD) observations, and in 13 Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate simulations. Moreover, the joint occurrences of precipitation and temperature extremes simulated by CMIP5 climate models are compared with those derived from the CRU and UD observations for warm/wet, warm/dry, cold/wet, and cold/dry combinations of joint extremes.more » The number of occurrences of these four combinations during the second half of the 20th century (1951–2004) is assessed on a common global grid. CRU and UD observations show substantial increases in the occurrence of joint warm/dry and warm/wet combinations for the period 1978–2004 relative to 1951–1977. The results show that with respect to the sign of change in the concurrent extremes, the CMIP5 climate model simulations are in reasonable overall agreement with observations. The results reveal notable discrepancies between regional patterns and the magnitude of change in individual climate model simulations relative to the observations of precipitation and temperature.« less

  11. Changes in Concurrent Precipitation and Temperature Extremes

    SciTech Connect

    Hao, Zengchao; AghaKouchak, Amir; Phillips, Thomas J.

    2013-08-01

    While numerous studies have addressed changes in climate extremes, analyses of concurrence of climate extremes are scarce, and climate change effects on joint extremes are rarely considered. This study assesses the occurrence of joint (concurrent) monthly continental precipitation and temperature extremes in Climate Research Unit (CRU) and University of Delaware (UD) observations, and in 13 Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate simulations. Moreover, the joint occurrences of precipitation and temperature extremes simulated by CMIP5 climate models are compared with those derived from the CRU and UD observations for warm/wet, warm/dry, cold/wet, and cold/dry combinations of joint extremes. The number of occurrences of these four combinations during the second half of the 20th century (1951–2004) is assessed on a common global grid. CRU and UD observations show substantial increases in the occurrence of joint warm/dry and warm/wet combinations for the period 1978–2004 relative to 1951–1977. The results show that with respect to the sign of change in the concurrent extremes, the CMIP5 climate model simulations are in reasonable overall agreement with observations. The results reveal notable discrepancies between regional patterns and the magnitude of change in individual climate model simulations relative to the observations of precipitation and temperature.

  12. Winter depression and diabetes.

    PubMed

    Ernst, Christine R

    2012-12-01

    Depression is a common and often harmful disorder, which is frequently associated with the winter season. Research has shown a link between type 2 diabetes mellitus and depression. Furthermore, diabetics with depression have a higher rate of adverse outcomes. Little has been published regarding the seasonality of depression in diabetics. The case report described in this article concerns a 65-year-old woman with type 2 diabetes and a history of winter depression. Current evidence-based management options are reviewed. PMID:23089656

  13. Preliminary Evidence for the Amplification of Global Warming in Shallow, Intertidal Estuarine Waters

    EPA Science Inventory

    Over the past 50 years, mean annual water temperature in northeastern U.S. estuaries has increased by approximately 1.2°C, with most of the warming recorded in the winter and early spring. We hypothesize that this warming may be amplified in the shallow (<2m), nearshore portions ...

  14. Global warming reduces plant reproductive output for temperate multi-inflorescence species on the Tibetan plateau.

    PubMed

    Liu, Yinzhan; Mu, Junpeng; Niklas, Karl J; Li, Guoyong; Sun, Shucun

    2012-07-01

    • Temperature is projected to increase more during the winter than during the summer in cold regions. The effects of winter warming on reproductive effort have not been examined for temperate plant species. • Here, we report the results of experimentally induced seasonal winter warming (0.4 and 2.4°C increases in growing and nongrowing seasons, respectively, using warmed and ambient open-top chambers in a Tibetan Plateau alpine meadow) for nine indeterminate-growing species producing multiple (single-flowered or multi-flowered) inflorescences and three determinate-growing species producing single inflorescences after a 3-yr period of warming. • Warming reduced significantly flower number and seed production per plant for all nine multi-inflorescence species, but not for the three single-inflorescence species. Warming had an insignificant effect on the fruit to flower number ratio, seed size and seed number per fruit among species. The reduction in seed production was largely attributable to the decline in flower number per plant. The flowering onset time was unaffected for nine of the 12 species. Therefore, the decline in flower production and seed production in response to winter warming probably reflects a physiological response (e.g. metabolic changes associated with flower production). • Collectively, the data indicate that global warming may reduce flower and seed production for temperate herbaceous species and will probably have a differential effect on single- vs multi-inflorescence species.

  15. Simulation of the December 1998 Stratospheric Major Warming

    NASA Technical Reports Server (NTRS)

    Manney, G. L.; Lahoz, W. A.; Swinbank, R.; ONeill, A.; Connew, P. M.; Zurek, R. W.

    1999-01-01

    Prior to 1991, major warmings (defined by increasing zonal mean temperatures and zonal mean easterly winds from 60degN to the pole at 10 hPa) typically occurred approximately once every two Arctic winters; a major warming in mid-Dec. 1998 was the first since Feb. 1991. The Dec. 1998 warming was also the second earliest on record. The earliest, and the only other major warming on record before the end of Dec. was in early Dec 1987; prior to that, the earliest was in late Dec./early Jan. 1984-85. The 1984-85 and 1987 warmings resulted in the warmest and weakest lower stratospheric polar vortices in the 20 years before 1998-99. Fig. 1 compares temperatures and vortex strength in 1998-99 with those in the previous 20 years, using the US National Center for Environmental Prediction (NCEP) record; 1987-88 and 1984-85 are also highlighted. The Dec. 1998 warming had a more pronounced effect on mid-stratospheric temperatures than the Dec. 1987 warming (Fig. 1a), although smaller than that of warmings later in winter (e.g., 1984-85). 10-hPa temperatures fell well below average again in late Jan. 1999 and remained unusually low until an early final warming began in late Feb. 840 K PV gradients (Fig. 1c) set a record minimum in Jan. 1999, but were near average in Feb before the final warming. The effect of the Dec. 1998 warming on lower stratospheric temperatures was comparable to that of other major warmings; there was a brief period of record-high minimum 46-hPa temperatures in early Jan 1999 (Fig. 1b), and temperatures then fell to near average for a short period in mid-Feb. Lower stratospheric PV gradients were the weakest on record during the 1998-99 winter (Fig. 1d). The evolution of the vortex and minimum temperatures during 1998-99 was remarkably similar to that during 1987-88, the only previous year when a major warming was observed before the end of Dec.

  16. Impact of declining Arctic sea ice on winter snowfall.

    PubMed

    Liu, Jiping; Curry, Judith A; Wang, Huijun; Song, Mirong; Horton, Radley M

    2012-03-13

    While the Arctic region has been warming strongly in recent decades, anomalously large snowfall in recent winters has affected large parts of North America, Europe, and east Asia. Here we demonstrate that the decrease in autumn Arctic sea ice area is linked to changes in the winter Northern Hemisphere atmospheric circulation that have some resemblance to the negative phase of the winter Arctic oscillation. However, the atmospheric circulation change linked to the reduction of sea ice shows much broader meridional meanders in midlatitudes and clearly different interannual variability than the classical Arctic oscillation. This circulation change results in more frequent episodes of blocking patterns that lead to increased cold surges over large parts of northern continents. Moreover, the increase in atmospheric water vapor content in the Arctic region during late autumn and winter driven locally by the reduction of sea ice provides enhanced moisture sources, supporting increased heavy snowfall in Europe during early winter and the northeastern and midwestern United States during winter. We conclude that the recent decline of Arctic sea ice has played a critical role in recent cold and snowy winters.

  17. Impacts of Climate Change On The Occurrence of Extreme Events: The Mice Project

    NASA Astrophysics Data System (ADS)

    Palutikof, J. P.; Mice Team

    It is widely accepted that climate change due to global warming will have substan- tial impacts on the natural environment, and on human activities. Furthermore, it is increasingly recognized that changes in the severity and frequency of extreme events, such as windstorm and flood, are likely to be more important than changes in the average climate. The EU-funded project MICE (Modelling the Impacts of Climate Extremes) commenced in January 2002. It seeks to identify the likely changes in the occurrence of extremes of rainfall, temperature and windstorm due to global warm- ing, using information from climate models as a basis, and to study the impacts of these changes in selected European environments. The objectives are: a) to evaluate, by comparison with gridded and station observations, the ability of climate models to successfully reproduce the occurrence of extremes at the required spatial and temporal scales. b) to analyse model output with respect to future changes in the occurrence of extremes. Statistical analyses will determine changes in (i) the return periods of ex- tremes, (ii) the joint probability of extremes (combinations of damaging events such as windstorm followed by heavy rain), (iii) the sequential behaviour of extremes (whether events are well-separated or clustered) and (iv) the spatial patterns of extreme event occurrence across Europe. The range of uncertainty in model predictions will be ex- plored by analysing changes in model experiments with different spatial resolutions and forcing scenarios. c) to determine the impacts of the predicted changes in extremes occurrence on selected activity sectors: agriculture (Mediterranean drought), commer- cial forestry and natural forest ecosystems (windstorm and flood in northern Europe, fire in the Mediterranean), energy use (temperature extremes), tourism (heat stress and Mediterranean beach holidays, changes in the snow pack and winter sports ) and civil protection/insurance (windstorm and flood

  18. Temperature extremes, density dependence, and southern pine beetle (Coleoptera: Curculionidae) population dynamics in east Texas.

    PubMed

    Friedenberg, Nicholas A; Sarkar, Sudipta; Kouchoukos, Nicholas; Billings, Ronald F; Ayres, Matthew P

    2008-06-01

    Previous studies of the southern pine beetle, Dendroctonus frontalis Zimm., established that its population in east Texas responds to a delayed density-dependent process, whereas no clear role of climate has been determined. We tested two biological hypotheses for the influence of extreme temperatures on annual southern pine beetle population growth in the context of four alternative hypotheses for density-dependent population regulation. The significance of climate variables and their interaction with population regulation depended on the model of density dependence. The best model included both direct and delayed density dependence of a cubic rather than linear form. Population growth declined with the number of days exceeding 32 degrees C, temperatures previously reported to reduce brood survival. Density dependence also changed with the number of hot days. Growth was highest in years with average minimum winter temperatures. Severely cold winters may reduce survival, whereas warm winters may reduce the efficiency of spring infestation formation. Whereas most previous studies have incorporated climate as an additive effect on growth, we found that the form of delayed density dependence changed with the number of days >32 degrees C. The interaction between temperature and regulation, a potentially common phenomenon in ecology, may explain why southern pine beetle outbreaks do not occur at perfectly regular intervals. Factors other than climate, such as forest management and direct suppression, may have contributed significantly to the timing, severity, and eventual cessation of outbreaks since the mid-1950s.

  19. Mammals in Winter.

    ERIC Educational Resources Information Center

    Wapner, Suzanne

    1985-01-01

    Mammals that tolerate the winter cold and stay active all year exploit the harsh northern climate to their advantage. By simple experiments and observation you can better understand their adaptations which include furry bodies, snowshoe feet, extra blubber, light coloration, and strategically distributed food caches. (JHZ)

  20. The News. Winter 2007

    ERIC Educational Resources Information Center

    Giles, Ray, Ed.

    2007-01-01

    This Winter 2007 quarterly newsletter from the Community College League of California includes: (1) Incumbents: Some Win, Some Lose in November Trustee Elections; (2) Voters Approve $2 Billion in Bonds; (3) Photos from the "Together We Can" conference; (4) Report, Media Criticize Transfer, Completion Rates and Colleges; (5) District Leader…

  1. Teaching Ecology in Winter.

    ERIC Educational Resources Information Center

    Clearing: Nature and Learning in the Pacific Northwest, 1984

    1984-01-01

    Presents ideas for teaching ecology in the winter. Suggested topic areas or units include snow insulation and density, snowflakes and snow crystals, goldenrod galls, bird behavior, survival techniques, bacteriology and decomposition, trees and keying, biomass and productivity, pollution, and soil organisms. A sample student activity sheet is…

  2. Winter Playscape Dreaming

    ERIC Educational Resources Information Center

    Keeler, Rusty

    2006-01-01

    Winter, like all seasons, adds a new sense of mystery and discovery to the world of young children. It is the time when they can study snowflakes, find icicles, or observe the birds that share their yards. This article presents ideas and suggestions on how to plan a playscape. A playscape is a man-made seasonal playground for young children. It…

  3. Winter Here and Now.

    ERIC Educational Resources Information Center

    Finlay, Joy

    This book contains a wide variety of winter-oriented ideas and activities that can be adapted to all elementary grade levels and can also be integrated into existing mathematics, science, social studies, and/or art programs. The activities aim to help students develop the skills of observation, appreciation, and problem solving as well as…

  4. Warmer winters modulate life history and energy storage but do not affect sensitivity to a widespread pesticide in an aquatic insect.

    PubMed

    Arambourou, Hélène; Stoks, Robby

    2015-10-01

    Despite the increased attention for the effects of pesticides under global warming no studies tested how winter warming affects subsequent sensitivity to pesticides. Winter warming is expected to cause delayed negative effects when it increases metabolic rates and thereby depletes energy reserves. Using a common-garden experiment, we investigated the combined effect of a 4 °C increase in winter temperature and subsequent exposure to chlorpyrifos in the aquatic larvae of replicated low- and high-latitude European populations of the damselfly Ischnura elegans. The warmer winter (8 °C) resulted in a higher winter survival and higher growth rates compared to the cold winter (4 °C) commonly experienced by European high-latitude populations. Low-latitude populations were better at coping with the warmer winter, indicating thermal adaptation to the local winter temperatures. Subsequent chlorpyrifos exposure at 20 °C induced strong negative effects on survival, growth rate, lipid content and acetylcholinesterase activity while phenoloxidase activity increased. These pesticide effects were not affected by winter warming. Our results suggest that for species where winter warming has positive effects on life history, no delayed effects on the sensitivity to subsequent pesticide exposure should be expected. PMID:26261878

  5. Impact of winter cooling on the northern part of the Black Sea.

    NASA Astrophysics Data System (ADS)

    Savchenko, Anatolii

    2016-07-01

    Climate change in the future may have a negative impact on many countries due to the increasing surface temperature and sea level rise. Probably, unprecedented largest positive trend of surface temperature, which observed since the mid XX century, has associated with increasing human activities around the world. Moreover, this warming will continue in this century, and at the end of the XXI century will be 2 - 5 ºC. Thus, investigation and monitoring of current climate are very important and necessary tasks. Regional model data (downscaling) and satellite data are used, because of underdeveloped network of meteorological stations in the northern part of the Black Sea region. Experiment of downscaling was carried out for the Black Sea region with a high spatial resolution of 0.22° x 0.22° for 1958 - 2007(daily values). For the Black Sea were also used satellite data of sea surface temperature(SST) from MyOcean-2 Project, which CNR(Rome) has reprocessed Pathfinder V5.2 (PFV52) AVHRR data over period 1981 - 2012 with daily gap-free maps (L4) at the original PFV52 resolution at 0.04° x 0.04°. Correlation between satellite SST and surface temperature from regional model climate are amounted 0,99. Thus, surface temperature of model and satellite data for the Black Sea is much correlated between yourself. The following integral characteristics of the Black Sea are referred to the area of sea limited by the 44 - 47º N and 28 - 34º E. Maximum cooling of the north-western part of the Black Sea in winter is occurs after invasion of cold air across the northern border of the basin. In addition, this water area is also interesting in the presence of her huge oil and gas reserves, as well as the construction of liquefied gas (crude oil) terminals. The maximum values of total heat flux (sensible + latent heat fluxes= Q) corresponding to the minimum values of SST are observed during the periods of the negative phase of the NAO. Besides, fluxes with extreme days P (Q) = 95

  6. Characteristics of atmospheric circulation patterns associated with extreme temperatures over North America in observations and climate models

    NASA Astrophysics Data System (ADS)

    Loikith, Paul C.

    Motivated by a desire to understand the physical mechanisms involved in future anthropogenic changes in extreme temperature events, the key atmospheric circulation patterns associated with extreme daily temperatures over North America in the current climate are identified. Several novel metrics are used to systematically identify and describe these patterns for the entire continent. The orientation, physical characteristics, and spatial scale of these circulation patterns vary based on latitude, season, and proximity to important geographic features (i.e., mountains, coastlines). The anomaly patterns associated with extreme cold events tend to be similar to, but opposite in sign of, those associated with extreme warm events, especially within the westerlies, and tend to scale with temperature in the same locations. The influence of the Pacific North American (PNA) pattern, the Northern Annular Mode (NAM), and the El Niño-Southern Oscillation (ENSO) on extreme temperature days and months shows that associations between extreme temperatures and the PNA and NAM are stronger than associations with ENSO. In general, the association with extremes tends to be stronger on monthly than daily time scales. Extreme temperatures are associated with the PNA and NAM in locations typically influenced by these circulation patterns; however many extremes still occur on days when the amplitude and polarity of these patterns do not favor their occurrence. In winter, synoptic-scale, transient weather disturbances are important drivers of extreme temperature days; however these smaller-scale events are often concurrent with amplified PNA or NAM patterns. Associations are weaker in summer when other physical mechanisms affecting the surface energy balance, such as anomalous soil moisture content, are associated with extreme temperatures. Analysis of historical runs from seventeen climate models from the CMIP5 database suggests that most models simulate realistic circulation patterns

  7. Middle-Atmosphere Polar Warming at Mars

    NASA Astrophysics Data System (ADS)

    McDunn, T. L.; Bougher, S. W.; Kleinboehl, A.; Forget, F.; Murphy, J. R.; Smith, M. D.; Mischna, M. A.

    2011-12-01

    Polar Warming (PW) is a dynamical feature of the Martian atmosphere that consists of a temperature enhancement over mid-to-high latitudes during winter, spring, and autumn. It produces a reversal of the meridional temperature gradient and temperature inversions over mid-to-high latitudes. This phenomenon is the result of a global Hadley circulation which is a thermally-direct response to diabatic forcing caused by: (a) differential insolation, and (b) absorption of solar infrared radiation by suspended dust [1-4]. Previous studies of PW [5-9] have been limited by data paucity. Consequently, several important aspects of PW climatology have gone unknown. Now, sufficient data is available for in-depth characterization of the structure and variability of this phenomenon in the middle atmosphere [manuscript in preparation]. In this paper we define a warming index and characterize PW as observed by MCS/MRO, SPICAM/Mars Express, and the accelerometer experiments that flew on MGS, Mars Odyssey, and MRO. During most seasons, PW manifests between p = 1-10 Pa and the top of the MCS dataset, and during seasons where SPICAM and ACC data are available, warming often persists through the extent of these data as well (i.e., up to p = 1.0 x 10-4 Pa). PW maximizes in the vertical between p = 1.9 to 0.5 Pa. We find the latitude of maximum temperature tends to move pole-ward with decreasing pressure, indicating a pole-ward slant with height of the descending branch of the Hadley cell. We find PW tends to be stronger on the nightside than on the dayside. As expected from previous studies, we find PW is stronger during northern winter solstice (Ls = 270°) than during southern winter solstice (Ls = 90°). Interestingly, however, we find PW in both the northern hemisphere and the southern hemisphere is stronger during Ls = 180° than during other seasons. This is unexpected because: (a) early studies focused on PW as strictly a winter phenomenon, and (b) dust optical depth is generally

  8. Establishing native warm season grasses on Eastern Kentucky strip mines

    SciTech Connect

    Barnes, T.G.; Larkin, J.L.; Arnett, M.B.

    1998-12-31

    The authors evaluated various methods of establishing native warm season grasses on two reclaimed Eastern Kentucky mines from 1994--1997. Most current reclamation practices incorporate the use of tall fescue (Festuca arundinacea) and other cool-season grasses/legumes that provide little wildlife habitats. The use of native warm season grasses will likely improve wildlife habitat on reclaimed strip mines. Objectives of this study were to compare the feasibility of establishing these grasses during fall, winter, or spring using a native rangeland seeder or hydroseeding; a fertilizer application at planting; or cold-moist stratification prior to hydroseeding. Vegetative cover, bare ground, species richness, and biomass samples were collected at the end of each growing season. Native warm season grass plantings had higher plant species richness compared to cool-season reclamation mixtures. There was no difference in establishment of native warm season grasses as a result of fertilization or seeding technique. Winter native warm season grass plantings were failures and cold-moist stratification did not increase plant establishment during any season. As a result of a drought during 1997, both cool-season and warm season plantings were failures. Cool-season reclamation mixtures had significantly more vegetative cover and biomass compared to native warm season grass mixtures and the native warm season grass plantings did not meet vegetative cover requirements for bond release. Forbs and legumes that established well included pale purple coneflower (Echinacea pallida), lance-leaf coreopsis (Coreopsis lanceolata), round-headed lespedeza (Lespedeza capitata), partridge pea (Cassia fasiculata), black-eyed susan (Rudbeckia hirta), butterfly milkweed (Asclepias tuberosa), and bergamot (Monarda fistulosa). Results from two demonstration plots next to research plots indicate it is possible to establish native warm season grasses on Eastern Kentucky strip mines for wildlife habitat.

  9. Deciduous Plant Twigs in Winter

    ERIC Educational Resources Information Center

    Clark, Eloise

    1977-01-01

    Describing, via illustration and narrative, the winter twigs found in the U.S., this article presents a sophisticated discussion of: beech, white ash, aspen, sycamore, red oak, butternut, and other winter twigs. (JC)

  10. A Pan-arctic Survey about the Meaning of Winter Respiration in Northern High Latitudes

    NASA Astrophysics Data System (ADS)

    Selbmann, A. K.; Natali, S.

    2015-12-01

    The arctic is warming at twice the rate of the rest of the planet, with the greatest warming occurring during the winter months. Despite the cold temperatures during the winter, microbial activity continues and leads to a release of soil carbon during a criticial period when plant uptake has ceased. Due to the warming climate, huge pools of carbon stored in permafrost soils are expected to be released to the atmosphere. To identify the annual carbon balance of arctic ecosystems and potential impacts caused by a rise in temperatures, understanding the magnitude of winter respiration is essential. In order to refine current and future estimates of carbon loss from permafrost ecosystems, we conducted a pan-arctic synthesis of winter respiration from northern high latitude regions. We examined differences in cumulative winter respiration among permafrost zones, biomes, ecosystem types, and effects of measurement method on winter respiration estimates. We also examined effect of air temperature and precipitation (Worldclim database) on rates of winter respiration. The database contained 169 measurement points from 46 study sites located throughout the permafrost zones. We found that 21.6 % of annual respiration is happening during non-growing season, which can shift ecosystems from annual sinks during the growing season to net sources of carbon on an annual basis. Across studies, the average carbon loss during the winter was 66 g CO2-C. There was a strong relationship between mean annual air temperature and winter respiration, and lower respiration in continuous compared to discontinuous permafrost zones and northern areas without permafrost. The present results clarify the contribution of winter respiration to annual carbon balance and show the sensitivity of carbon release to rising temperatures in northern high latitudes. These results suggest that permafrost degradation and increased temperature will lead to a higher release of carbon from the Arctic in wintertime

  11. Warm Dense Matter: An Overview

    SciTech Connect

    Kalantar, D H; Lee, R W; Molitoris, J D

    2004-04-21

    This document provides a summary of the ''LLNL Workshop on Extreme States of Materials: Warm Dense Matter to NIF'' which was held on 20, 21, and 22 February 2002 at the Wente Conference Center in Livermore, CA. The warm dense matter regime, the transitional phase space region between cold material and hot plasma, is presently poorly understood. The drive to understand the nature of matter in this regime is sparking scientific activity worldwide. In addition to pure scientific interest, finite temperature dense matter occurs in the regimes of interest to the SSMP (Stockpile Stewardship Materials Program). So that obtaining a better understanding of WDM is important to performing effective experiments at, e.g., NIF, a primary mission of LLNL. At this workshop we examined current experimental and theoretical work performed at, and in conjunction with, LLNL to focus future activities and define our role in this rapidly emerging research area. On the experimental front LLNL plays a leading role in three of the five relevant areas and has the opportunity to become a major player in the other two. Discussion at the workshop indicated that the path forward for the experimental efforts at LLNL were two fold: First, we are doing reasonable baseline work at SPLs, HE, and High Energy Lasers with more effort encouraged. Second, we need to plan effectively for the next evolution in large scale facilities, both laser (NIF) and Light/Beam sources (LCLS/TESLA and GSI) Theoretically, LLNL has major research advantages in areas as diverse as the thermochemical approach to warm dense matter equations of state to first principles molecular dynamics simulations. However, it was clear that there is much work to be done theoretically to understand warm dense matter. Further, there is a need for a close collaboration between the generation of verifiable experimental data that can provide benchmarks of both the experimental techniques and the theoretical capabilities. The conclusion of this

  12. Global warming and the hydrologic cycle

    NASA Astrophysics Data System (ADS)

    Loaiciga, Hugo A.; Valdes, Juan B.; Vogel, Richard; Garvey, Jeff; Schwarz, Harry

    1996-01-01

    Starting with a review of the basic processes that govern greenhouse warming, we have demonstrated that the hydrologic cycle plays a key role in the heat balance of the Earth's surface—atmosphere system. Through the water and other climatic feedbacks, the hydrologic cycle is shown to be a key factor in the climate's evolution as greenhouse gases continue to build up in the atmosphere. This paper examines the current predictive capability of general circulation models linked with macroscale and landscape-scale hydrologic models that simulate regional and local hydrologic regimes under global warming scenarios. Issues concerning hydrologic model calibration and validation in the context of climate change are addressed herein. It is shown that the natural uncertainty in hydrologic regimes in the present climate introduces a signal-to-noise interpretation problem for discerning greenhouse-induced variations in regional hydrologic regimes. Simulations of river basins by means of macroscale hydrologic models nested within general circulation models have been implemented in a few selected cases. From the perspective of water resources management, such simulations, carried out in detail under greenhouse-warming scenarios in midlatitudinal basins of the United States, predict shorter winter seasons, larger winter floods, drier and more frequent summer weather, and overall enhanced and protracted hydrologic variability. All these predictions point to potentially worsening conditions for flood control, water storage, and water supply in areas of semiarid midlatitudinal climate currently dependent of spring snowmelt. Little information of this type is currently available for other areas of the world. Practice of sound water resources engineering principles ought to be adequate to cope with additional hydrologic uncertainty that might arise from global warming.

  13. Evaluating the Large-Scale Environment of Extreme Events Using Reanalyses

    NASA Astrophysics Data System (ADS)

    Bosilovich, M. G.; Schubert, S. D.; Koster, R. D.; da Silva, A. M., Jr.; Eichmann, A.

    2014-12-01

    Extreme conditions and events have always been a long standing concern in weather forecasting and national security. While some evidence indicates extreme weather will increase in global change scenarios, extremes are often related to the large scale atmospheric circulation, but also occurring infrequently. Reanalyses assimilate substantial amounts of weather data and a primary strength of reanalysis data is the representation of the large-scale atmospheric environment. In this effort, we link the occurrences of extreme events or climate indicators to the underlying regional and global weather patterns. Now, with greater than 3o years of data, reanalyses can include multiple cases of extreme events, and thereby identify commonality among the weather to better characterize the large-scale to global environment linked to the indicator or extreme event. Since these features are certainly regionally dependent, and also, the indicators of climate are continually being developed, we outline various methods to analyze the reanalysis data and the development of tools to support regional evaluation of the data. Here, we provide some examples of both individual case studies and composite studies of similar events. For example, we will compare the large scale environment for Northeastern US extreme precipitation with that of highest mean precipitation seasons. Likewise, southerly winds can shown to be a major contributor to very warm days in the Northeast winter. While most of our development has involved NASA's MERRA reanalysis, we are also looking forward to MERRA-2 which includes several new features that greatly improve the representation of weather and climate, especially for the regions and sectors involved in the National Climate Assessment.

  14. Projected changes in snowfall extremes and interannual variability of snowfall in the western United States

    NASA Astrophysics Data System (ADS)

    Lute, A. C.; Abatzoglou, J. T.; Hegewisch, K. C.

    2015-02-01

    Projected warming will have significant impacts on snowfall accumulation and melt, with implications for water availability and management in snow-dominated regions. Changes in snowfall extremes are confounded by projected increases in precipitation extremes. Downscaled climate projections from 20 global climate models were bias-corrected to montane Snowpack Telemetry stations across the western United States to assess mid-21st century changes in the mean and variability of annual snowfall water equivalent (SFE) and extreme snowfall events, defined by the 90th percentile of cumulative 3 day SFE amounts. Declines in annual SFE and number of snowfall days were projected for all stations. Changes in the magnitude of snowfall event quantiles were sensitive to historical winter temperature. At climatologically cooler locations, such as in the Rocky Mountains, changes in the magnitude of snowfall events mirrored changes in the distribution of precipitation events, with increases in extremes and less change in more moderate events. By contrast, declines in snowfall event magnitudes were found for all quantiles in warmer locations. Common to both warmer and colder sites was a relative increase in the magnitude of snowfall extremes compared to annual SFE and a larger fraction of annual SFE from snowfall extremes. The coefficient of variation of annual SFE increased up to 80% in warmer montane regions due to projected declines in snowfall days and the increased contribution of snowfall extremes to annual SFE. In addition to declines in mean annual SFE, more frequent low-snowfall years and less frequent high-snowfall years were projected for every station.

  15. Winter Wilderness Travel and Camping.

    ERIC Educational Resources Information Center

    Gilchrest, Norman

    Knowledge and skill are needed for safe and enjoyable travel and camping in the wilderness in winter. The beauty of snow and ice, reduced human use, and higher tolerance of animals toward humans make the wilderness attractive during winter. The uniqueness of winter travel presents several challenges that are not present in other seasons. Safety is…

  16. Trend analysis of extreme climate indices using simulated temperature and precipitation time series for the Carpathian basin

    NASA Astrophysics Data System (ADS)

    Pongracz, R.; Bartholy, J.; Szabo, P.; Kovacs, G.

    2009-09-01

    Global warming may be recognized both in shifts of regional mean climate, and also, in the frequency and intensity changes of different climate extremes. Several climate extreme indices are analyzed and compared for the Carpathian basin (located in Central/Eastern Europe) following the guidelines suggested by the joint WMO-CCl/CLIVAR Working Group on climate change detection. Our statistical trend analysis includes the evaluation of several extreme temperature and precipitation indices using different threshold values. In order to evaluate the expected trends (by 2071-2100 relative to the 1961-1990 reference period) in the Carpathian basin, daily values of meteorological variables are obtained from the outputs of various regional climate model (RCM) experiments accomplished in the frame of the completed EU-project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). Horizontal resolution of the applied RCMs is 50 km. Two emission scenarios (A2 and B2) are used to compare past and future simulated values of the extreme climate indices for the Carpathian basin. Furthermore, fine-resolution climate experiments of two additional RCMs adapted and run at the Department of Meteorology, Eotvos Lorand University are used to extend the trend analysis of climate extremes for the Carpathian basin. (1) Model PRECIS (run at 25 km horizontal resolution) was developed at the UK Met Office, Hadley Centre, and it uses the boundary conditions from the HadCM3 GCM. (2) Model RegCM3 (run at 10 km horizontal resolution) was developed by Giorgi et al. and it is available from the ICTP (International Centre for Theoretical Physics). Analysis of the simulated daily temperature datasets suggests that the detected regional warming is expected to continue in the 21st century. Cold temperature extremes are projected to decrease while warm extremes tend to increase significantly. Expected changes of annual precipitation indices are

  17. Ecosystem Greenhouse Gas Fluxes Respond Directly to Weather Not Climate: A Case Study on the Relationship of Global Atmospheric Circulation, Foehn Frequency, and Winter Weather to Northern Alps Regional Grassland Phenology and Carbon Cycling

    NASA Astrophysics Data System (ADS)

    Desai, A. R.; Wohlfahrt, G.; Zeeman, M. J.; Katata, G.; Mauder, M.; Schmid, H. P. E.

    2014-12-01

    The impact of climate change on regional ecosystem structure and biogeochemical cycling has two important aspects that require better elaboration to improve projections of these effects. The first is that ecosystems don't respond directly to climate, but indirectly via frequency and occurrence of weather systems, which are driven by climatic shifts in global circulation and radiative processes. The second is that many responses of ecosystems to these weather patterns and extremes are lagged in time. Here, we examine these aspects for northern Alpine grasslands. Long-term eddy covariance flux tower and phenology observations in Austria and Germany and biophysical models reveal a strong influence of winter air temperature, snowfall, and snowmelt frequency on winter grass mortality and spring grassland carbon uptake. Further, the mode of climate variability that drives winter air temperature and snow depth patterns is primarily the frequency of strong regional southerly Foehn flow that promotes warm, dry conditions in winter. Finally, we demonstrate that much of the interannual variance in Foehn frequency and southerly flow is driven by statistics and climatic trends of 500 hPa pressure patterns in Greenland, part of the Arctic Oscillation. However, a few years, including the unusually warm and dry winter of 2013-2014 appear to have secondary, possibly local thermotopographic circulation factors that promoted its weather conditions regionally, which also included primarily cool and wet conditions in northern Europe and the southern Alps. These findings demonstrate that the regional response of ecosystems to climate change is modulated by how large-scale circulation patterns influence local meteorology and topographic flows both during and outside the growing season and provides a framework for future assessment and climate model improvements of linkages of climate change, weather patterns, and ecosystem responses.

  18. A successful forecast of an El Nino winter

    SciTech Connect

    Kerr, R.A.

    1992-01-24

    This year, for the first time, weather forecasters used signs of a warming in the tropical Pacific as the basis for a long-range prediction of winter weather patterns across the United States. Now forecasters are talking about the next step: stretching the lead time for such forecasts by a year or more. That seems feasible because although this Pacific warming was unmistakable by the time forecasters at the National Weather Service's Climate Analysis Center (CAC) in Camp Springs, Maryland, issued their winter forecast, the El Nino itself had been predicted almost 2 years in advance by a computer model. Next time around, the CAC may well be listening to the modelers and predicting El Nino-related patterns of warmth and flooding seasons in advance.

  19. Warm autoimmune hemolytic anemia.

    PubMed

    Naik, Rakhi

    2015-06-01

    Warm autoimmune hemolytic anemia (AIHA) is defined as the destruction of circulating red blood cells (RBCs) in the setting of anti-RBC autoantibodies that optimally react at 37°C. The pathophysiology of disease involves phagocytosis of autoantibody-coated RBCs in the spleen and complement-mediated hemolysis. Thus far, treatment is aimed at decreasing autoantibody production with immunosuppression or reducing phagocytosis of affected cells in the spleen. The role of complement inhibitors in warm AIHA has not been explored. This article addresses the diagnosis, etiology, and treatment of warm AIHA and highlights the role of complement in disease pathology.

  20. Winter ecology of spectacled eiders: Environmental characteristics and population change

    USGS Publications Warehouse

    Petersen, M.R.; Douglas, D.C.

    2004-01-01

    We described characteristics of the wintering area used by Spectacled Eiders (Somateria fischeri) in the Bering Sea, Alaska, and evaluated these characteristics in relation to long-term population trends. Remoteness, limited daylight, and extreme weather conditions precluded direct observations, so we derived the location of the wintering area from satellite telemetry, ice conditions from remotely sensed data, weather conditions from archived data sets, and benthic communities from the literature. Based on analyses of two indices spanning 1957-2002 and 1988-2002, we identified no single environmental parameter that explained the precipitous decline in nesting populations in western Alaska. In general, we found that the number of days with extreme sea ice in winter, extreme winds, and winds in spring explained the greatest variability in annual indices. These analyses support the conclusion that annual population estimates on the breeding grounds can be negatively impacted by extended periods of dense sea-ice concentration and weather during the previous winter. Examination of population indices did not support the hypothesis that changes in benthic community on the wintering grounds have contributed to the decline or inhibited the recovery of the Spectacled Eider breeding population in western Alaska.

  1. Warm and Cool Dinosaurs.

    ERIC Educational Resources Information Center

    Mannlein, Sally

    2001-01-01

    Presents an art activity in which first grade students draw dinosaurs in order to learn about the concept of warm and cool colors. Explains how the activity also helped the students learn about the concept of distance when drawing. (CMK)

  2. Draft global warming study

    SciTech Connect

    Not Available

    1990-01-01

    The 1990 Resource Program Global Warming Study examines potential Bonneville Power Administration (BPA) resource alternatives related to the risk of global warming. The study evaluates strategies for reducing net carbon emissions, and identifies the net carbon contribution of certain resource strategies designed to reduce those emissions. Carbon dioxide (CO{sub 2}) is the greenhouse gas'' most associated with electricity production. The main purpose of the global warming study is to identify possible courses of action that BPA might take to reduce its contributions to the risk of global warming and to estimate the efficacy and costs of each approach. The principal measure of effectiveness is the reduction in total atmospheric carbon emissions compared to a base case. 13 refs., 2 tabs.

  3. Reconciling Warming Trends

    NASA Technical Reports Server (NTRS)

    Schmidt, Gavin A.; Shindell, Drew T.; Tsigaridis, Konstantinos

    2014-01-01

    Climate models projected stronger warming over the past 15 years than has been seen in observations. Conspiring factors of errors in volcanic and solar inputs, representations of aerosols, and El NiNo evolution, may explain most of the discrepancy.

  4. Decreased winter severity increases viability of a montane frog population

    PubMed Central

    McCaffery, Rebecca M.; Maxell, Bryce A.

    2010-01-01

    Many proximate causes of global amphibian declines have been well documented, but the role that climate change has played and will play in this crisis remains ambiguous for many species. Breeding phenology and disease outbreaks have been associated with warming temperatures, but, to date, few studies have evaluated effects of climate change on individual vital rates and subsequent population dynamics of amphibians. We evaluated relationships among local climate variables, annual survival and fecundity, and population growth rates from a 9-year demographic study of Columbia spotted frogs (Rana luteiventris) in the Bitterroot Mountains of Montana. We documented an increase in survival and breeding probability as severity of winter decreased. Therefore, a warming climate with less severe winters is likely to promote population viability in this montane frog population. More generally, amphibians and other ectotherms inhabiting alpine or boreal habitats at or near their thermal ecological limits may benefit from the milder winters provided by a warming climate as long as suitable habitats remain intact. A more thorough understanding of how climate change is expected to benefit or harm amphibian populations at different latitudes and elevations is essential for determining the best strategies to conserve viable populations and allow for gene flow and shifts in geographic range. PMID:20421473

  5. Decreased winter severity increases viability of a montane frog population.

    PubMed

    McCaffery, Rebecca M; Maxell, Bryce A

    2010-05-11

    Many proximate causes of global amphibian declines have been well documented, but the role that climate change has played and will play in this crisis remains ambiguous for many species. Breeding phenology and disease outbreaks have been associated with warming temperatures, but, to date, few studies have evaluated effects of climate change on individual vital rates and subsequent population dynamics of amphibians. We evaluated relationships among local climate variables, annual survival and fecundity, and population growth rates from a 9-year demographic study of Columbia spotted frogs (Rana luteiventris) in the Bitterroot Mountains of Montana. We documented an increase in survival and breeding probability as severity of winter decreased. Therefore, a warming climate with less severe winters is likely to promote population viability in this montane frog population. More generally, amphibians and other ectotherms inhabiting alpine or boreal habitats at or near their thermal ecological limits may benefit from the milder winters provided by a warming climate as long as suitable habitats remain intact. A more thorough understanding of how climate change is expected to benefit or harm amphibian populations at different latitudes and elevations is essential for determining the best strategies to conserve viable populations and allow for gene flow and shifts in geographic range.

  6. Global Warming: Settled Science? Unsettled Media Debate??

    NASA Astrophysics Data System (ADS)

    Schneider, S. H.

    2007-12-01

    The Intergovernmental Panel on Climate Change recently assessed the approximate 0.75°C warming since 1850 as an "unequivocal" trend. This is very rare and strong language for scientists who often lead with their caveats, not with their concerns. Later, the same report says it is "very likely" (i.e.- greater that 90% chance) that most of the warming of the past several decades can be attributed to human activities, primarily greenhouse gas emissions. So far, the science sounds "settled". Furthermore, the IPCC, as well as many other national assessments, assigns very high confidence to projections of further warming, intensified tropical cyclones, more extremes of drought and flood, and melting mountain glaciers and arctic sea ice in the twenty-first century. Still sounds settled. However, the likely range of warming projected by IPCC to 2100 varies by a whopping factor of 6: 1.1-6.4°C above 1990 levels-- hardly "settled science". Projections of precipitation are equivocal even as to the direction of change. Therefore, IPCC Working Group 2 recommends a "risk management" approach to dealing with the combination of well establish and remaining speculative components of global warming that nonetheless pose potentially serious risks to human and natural systems.

  7. Polar Warming Drivers

    NASA Astrophysics Data System (ADS)

    McDunn, T. L.; Bougher, S. W.; Mischna, M. A.; Murphy, J. R.

    2012-12-01

    Polar warming is a dynamically induced temperature enhancement over mid-to-high latitudes that results in a reversed (poleward) meridional temperature gradient. This phenomenon was recently characterized over the 40-90 km altitude region [1] based on nearly three martian years of Mars Climate Sounder observations [2, 3]. Here we investigate which forcing mechanisms affect the magnitude and distribution of the observed polar warming by conducting simulations with the Mars Weather Research and Forecasting General Circulation Model [4, 5]. We present simulations confirming the influence topography [6] and dust loading [e.g., 7] have upon polar warming. We then present simulations illustrating the modulating influence gravity wave momentum deposition exerts upon polar warming, consistent with previous modeling studies [e.g., 8]. The results of this investigation suggest the magnitude and distribution of polar warming in the martian middle atmosphere is modified by gravity wave activity and that the characteristics of the gravity waves that most significantly affect polar warming vary with season. References: [1] McDunn, et al., 2012 (JGR), [2]Kleinböhl, et al., 2009 (JGR), [3] Kleinböhl, et al., 2011 (JQSRT), [4] Richardson, et al., 2007 (JGR), [5] Mischna, et al., 2011 (Planet. Space Sci.), [6] Richardson and Wilson, 2002 (Nature), [7] Haberle, et al., 1982 (Icarus), [8] Barnes, 1990 (JGR).

  8. Divergence of the diapause transcriptome in apple maggot flies: winter regulation and post-winter transcriptional repression.

    PubMed

    Meyers, Peter J; Powell, Thomas H Q; Walden, Kimberly K O; Schieferecke, Adam J; Feder, Jeffrey L; Hahn, Daniel A; Robertson, Hugh M; Berlocher, Stewart H; Ragland, Gregory J

    2016-09-01

    The duration of dormancy regulates seasonal timing in many organisms and may be modulated by day length and temperature. Though photoperiodic modulation has been well studied, temperature modulation of dormancy has received less attention. Here, we leverage genetic variation in diapause in the apple maggot fly, Rhagoletis pomonella, to test whether gene expression during winter or following spring warming regulates diapause duration. We used RNAseq to compare transcript abundance during and after simulated winter between an apple-infesting population and a hawthorn-infesting population where the apple population ends pupal diapause earlier than the hawthorn-infesting population. Marked differences in transcription between the two populations during winter suggests that the 'early' apple population is developmentally advanced compared with the 'late' hawthorn population prior to spring warming, with transcripts participating in growth and developmental processes relatively up-regulated in apple pupae during the winter cold period. Thus, regulatory differences during winter ultimately drive phenological differences that manifest themselves in the following summer. Expression and polymorphism analysis identify candidate genes in the Wnt and insulin signaling pathways that contribute to population differences in seasonality. Both populations remained in diapause and displayed a pattern of up- and then down-regulation (or vice versa) of growth-related transcripts following warming, consistent with transcriptional repression. The ability to repress growth stimulated by permissive temperatures is likely critical to avoid mismatched phenology and excessive metabolic demand. Compared with diapause studies in other insects, our results suggest some overlap in candidate genes/pathways, though the timing and direction of changes in transcription are likely species specific. PMID:27312473

  9. Climate change in our backyards: the reshuffling of North America's winter bird communities.

    PubMed

    Princé, Karine; Zuckerberg, Benjamin

    2015-02-01

    Much of the recent changes in North American climate have occurred during the winter months, and as result, overwintering birds represent important sentinels of anthropogenic climate change. While there is mounting evidence that bird populations are responding to a warming climate (e.g., poleward shifts) questions remain as to whether these species-specific responses are resulting in community-wide changes. Here, we test the hypothesis that a changing winter climate should favor the formation of winter bird communities dominated by warm-adapted species. To do this, we quantified changes in community composition using a functional index--the Community Temperature Index (CTI)--which measures the balance between low- and high-temperature dwelling species in a community. Using data from Project FeederWatch, an international citizen science program, we quantified spatiotemporal changes in winter bird communities (n = 38 bird species) across eastern North America and tested the influence of changes in winter minimum temperature over a 22-year period. We implemented a jackknife analysis to identify those species most influential in driving changes at the community level and the population dynamics (e.g., extinction or colonization) responsible for these community changes. Since 1990, we found that the winter bird community structure has changed with communities increasingly composed of warm-adapted species. This reshuffling of winter bird communities was strongest in southerly latitudes and driven primarily by local increases in abundance and regional patterns of colonization by southerly birds. CTI tracked patterns of changing winter temperature at different temporal scales ranging from 1 to 35 years. We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America.

  10. Climate change in our backyards: the reshuffling of North America's winter bird communities.

    PubMed

    Princé, Karine; Zuckerberg, Benjamin

    2015-02-01

    Much of the recent changes in North American climate have occurred during the winter months, and as result, overwintering birds represent important sentinels of anthropogenic climate change. While there is mounting evidence that bird populations are responding to a warming climate (e.g., poleward shifts) questions remain as to whether these species-specific responses are resulting in community-wide changes. Here, we test the hypothesis that a changing winter climate should favor the formation of winter bird communities dominated by warm-adapted species. To do this, we quantified changes in community composition using a functional index--the Community Temperature Index (CTI)--which measures the balance between low- and high-temperature dwelling species in a community. Using data from Project FeederWatch, an international citizen science program, we quantified spatiotemporal changes in winter bird communities (n = 38 bird species) across eastern North America and tested the influence of changes in winter minimum temperature over a 22-year period. We implemented a jackknife analysis to identify those species most influential in driving changes at the community level and the population dynamics (e.g., extinction or colonization) responsible for these community changes. Since 1990, we found that the winter bird community structure has changed with communities increasingly composed of warm-adapted species. This reshuffling of winter bird communities was strongest in southerly latitudes and driven primarily by local increases in abundance and regional patterns of colonization by southerly birds. CTI tracked patterns of changing winter temperature at different temporal scales ranging from 1 to 35 years. We conclude that a shifting winter climate has provided an opportunity for smaller, southerly distributed species to colonize new regions and promote the formation of unique winter bird assemblages throughout eastern North America. PMID:25322929

  11. Will loss of snow cover during climatic warming expose New Zealand alpine plants to increased frost damage?

    PubMed

    Bannister, Peter; Maegli, Tanja; Dickinson, Katharine J M; Halloy, Stephan R P; Knight, Allison; Lord, Janice M; Mark, Alan F; Spencer, Katrina L

    2005-06-01

    If snow cover in alpine environments were reduced through climatic warming, plants that are normally protected by snow-lie in winter would become exposed to greater extremes of temperature and solar radiation. We examined the annual course of frost resistance of species of native alpine plants from southern New Zealand that are normally buried in snowbanks over winter (Celmisia haastii and Celmisia prorepens) or in sheltered areas that may accumulate snow (Hebe odora) and other species, typical of more exposed areas, that are relatively snow-free (Celmisia viscosa, Poa colensoi, Dracophyllum muscoides). The frost resistance of these principal species was in accord with habitat: those from snowbanks or sheltered areas showed the least frost resistance, whereas species from exposed areas had greater frost resistance throughout the year. P. colensoi had the greatest frost resistance (-32.5 degrees C). All the principal species showed a rapid increase in frost resistance from summer to early winter (February-June) and maximum frost resistance in winter (July-August). The loss of resistance in late winter to early summer (August-December) was most rapid in P. colensoi and D. muscoides. Seasonal frost resistance of the principal species was more strongly related to daylength than to temperature, although all species except C. viscosa were significantly related to temperature when the influence of daylength was accounted for. Measurements of chlorophyll fluorescence indicated that photosynthetic efficiency of the principal species declined with increasing daylength. Levels of frost resistance of the six principal alpine plant species, and others measured during the growing season, were similar to those measured in tropical alpine areas and somewhat more resistant than those recorded in alpine areas of Europe. The potential for frost damage was greatest in spring. The current relationship of frost resistance with daylength is sufficient to prevent damage at any time of

  12. Winter photosynthetic activity of twenty temperate semi-desert sand grassland species.

    PubMed

    Tuba, Zoltán; Csintalan, Zsolt; Szente, Kálmán; Nagy, Zoltán; Fekete, Gábor; Larcher, Walter; Lichtenthaler, Hartmut K

    2008-09-29

    The winter photosynthetic activity (quantified by net CO(2) assimilation rates and chlorophyll (Chl) a fluorescence parameters) of 20 plant species (including two lichens and two mosses) of a Hungarian temperate semi-desert sand grassland was determined on one occasion per year in 1984, 1989 and 1994. Throughout winter, the overwintering green shoots, leaves or thalli were regularly exposed to below zero temperatures at night and daytime temperatures of 0-5 degrees C. In situ tissue temperature varied between -2.1 and +6.9 degrees C and the photosynthetic photon flux density (PPFD) between 137 and 351 micromol m(-2)s(-1). Under these conditions 18 of the grassland species exhibited photosynthetic CO(2) uptake (range: vascular plants ca. 0.2-3.8 micromol m(-2)s(-1), cryptogams 0.3-2.79 micromol kg(-1)s(-1)) and values of 0.9-5.1 of the Chl fluorescence decrease ratio R(Fd). In 1984, Festuca vaginata and Sedum sexangulare had net CO(2) assimilation at leaf temperatures of -0.85 to -1.2 degrees C. In 1989, all species except Cladonia furcata showed net CO(2) assimilation at tissue temperatures of 0 to +3.3 degrees C, with the highest rates observed in Poa bulbosa and F. vaginata. The latter showed a net CO(2) assimilation saturation at a PPFD of 600 micromol m(-2)s(-1) and a temperature optimum between +5 and +18 degrees C. At the 1994 measurements, the photosynthetic rates were higher at higher tissue water contents. The two mosses and lichens had a net photosynthesis (range: 1.1-2.79 micromol CO(2)kg(-1)s(-1)) at 2 degrees C tissue temperature and at 4-5 degrees C air temperature. Ca. 80% of the vascular grassland plant species maintained a positive C-balance during the coldest periods of winter, with photosynthetic rates of 1.5-3.8 micromol CO(2)m(-2)s(-1). In an extremely warm beginning March of the relatively warm winter of 2006/2007, the dicotyledonous plants had much higher CO(2) assimilation rates on a Chl (range 6-14.9 micromol g(-1)Chl s(-1)) and on a dry

  13. The recent warming trend in North Greenland

    NASA Astrophysics Data System (ADS)

    Orsi, Anais; Kawamura, Kenji; Masson-Delmotte, Valerie; Landais, Amaelle; Severinghaus, Jeff

    2015-04-01

    The arctic is the fastest warming region on Earth, but it is also one where there is little historical data. Although summer warming causes melt, the annual temperature trend is dominated by the winter and fall season, which are much less well documented. In addition, the instrumental record relies principally on coastal weather stations, and there are very few direct temperature observations in the interior dating back more than 30 years, especially in North Greenland, where the current warming trend is the largest. Here, we present a temperature reconstruction from NEEM (51°W, 77°N), in North Greenland, for the last 100 years, which allows us to put the recent trend in the context of the longer term climate. We use a combination of two independent proxies to reconstruct the temperature history at NEEM: borehole temperature and inert gas isotope measurements in the firn. Borehole temperature takes advantage of the low temperature diffusivity of the snow and ice, which allows the temperature history to be preserved in the ice for several centuries. Temperature gradients in the firn (old snow above the ice) influence the gas isotopic composition: thermal fractionation causes heavy isotopes to concentrate on the cold end of the firn column. We measured the isotopes of inert gases (N2, Ar and Kr), which have a constant atmospheric composition through time, and use the thermal fractionation signal as an additional constraint on the temperature history at the site. We find that NEEM has been warming by 0.86±0.22°C/decade over the past 30 years, from -28.55±0.29°C for the 1900-1970 average to -26.77±0.16°C for the 2000-2010 average. The warming rate at NEEM is similar to that of Greenland Summit, and confirms the large warming trends in North Greenland (polar amplification) and high altitude sites (tropospheric rather than surface warming). Water isotopes show that the recent past has not met the level of the 1928 anomaly; but the average of the past 30 years has

  14. Winter Frost and Fog

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30oS. The subtle, wavy pattern is a manifestation of fog.

    Location near: 28oS, 286oW Illumination from: upper left Season: Southern Winter

  15. Warm up to the idea: Global warming is here

    SciTech Connect

    Lynch, C.F.

    1996-07-01

    This article summarizes recent information about global warming as well as the history of greenhouse gas emissions which have lead to more and more evidence of global warming. The primary source detailed is the second major study report on global warming by the Intergovernmental Panel on climate change. Along with comments about the environmental effects of global warming such as coastline submersion, the economic, social and political aspects of alleviating greenhouse emissions and the threat of global warming are discussed.

  16. Long range global warming

    SciTech Connect

    Rolle, K.C.; Pulkrabek, W.W.; Fiedler, R.A.

    1995-12-31

    This paper explores one of the causes of global warming that is often overlooked, the direct heating of the environment by engineering systems. Most research and studies of global warming concentrate on the modification that is occurring to atmospheric air as a result of pollution gases being added by various systems; i.e., refrigerants, nitrogen oxides, ozone, hydrocarbons, halon, and others. This modification affects the thermal radiation balance between earth, sun and space, resulting in a decrease of radiation outflow and a slow rise in the earth`s steady state temperature. For this reason the solution to the problem is perceived as one of cleaning up the processes and effluents that are discharged into the environment. In this paper arguments are presented that suggest, that there is a far more serious cause for global warming that will manifest itself in the next two or three centuries; direct heating from the exponential growth of energy usage by humankind. Because this is a minor contributor to the global warming problem at present, it is overlooked or ignored. Energy use from the combustion of fuels and from the output of nuclear reactions eventually is manifest as warming of the surroundings. Thus, as energy is used at an ever increasing rate the consequent global warming also increases at an ever increasing rate. Eventually this rate will become equal to a few percent of solar radiation. When this happens the earth`s temperature will have risen by several degrees with catastrophic results. The trends in world energy use are reviewed and some mathematical models are presented to suggest future scenarios. These models can be used to predict when the global warming problem will become undeniably apparent, when it will become critical, and when it will become catastrophic.

  17. The impact of winter and spring temperatures on temperate tree budburst dates: results from an experimental climate manipulation.

    PubMed

    Fu, Yongshuo H; Campioli, Matteo; Deckmyn, Gaby; Janssens, Ivan A

    2012-01-01

    Budburst phenology is a key driver of ecosystem structure and functioning, and it is sensitive to global change. Both cold winter temperatures (chilling) and spring warming (forcing) are important for budburst. Future climate warming is expected to have a contrasting effect on chilling and forcing, and subsequently to have a non-linear effect on budburst timing. To clarify the different effects of warming during chilling and forcing phases of budburst phenology in deciduous trees, (i) we conducted a temperature manipulation experiment, with separate winter and spring warming treatments on well irrigated and fertilized saplings of beech, birch and oak, and (ii) we analyzed the observations with five temperature-based budburst models (Thermal Time model, Parallel model, Sequential model, Alternating model, and Unified model). The results show that both winter warming and spring warming significantly advanced budburst date, with the combination of winter plus spring warming accelerating budburst most. As expected, all three species were more sensitive to spring warming than to winter warming. Although the different chilling requirement, the warming sensitivity was not significantly different among the studied species. Model evaluation showed that both one- and two- phase models (without and with chilling, respectively) are able to accurately predict budburst. For beech, the Sequential model reproduced budburst dates best. For oak and birch, both Sequential model and the Thermal Time model yielded good fit with the data but the latter was slightly better in case of high parameter uncertainty. However, for late-flushing species, the Sequential model is likely be the most appropriate to predict budburst data in a future warmer climate. PMID:23071786

  18. Changes in Terrestrial Water Availability under Global Warming

    NASA Astrophysics Data System (ADS)

    Lan, C. W.; Lo, M. H.; Chou, C.

    2014-12-01

    Under global warming, the annual range of precipitation is widening (Chou and Lan, 2012; Chou et al., 2013) and the frequency of precipitation extreme events also increases. Due to nonlinear responses of land hydrological process to precipitation extremes, runoff can increase exponentially, and on the hard hand, soil water storage may decline. In addition, IPCC AR5 indicates that soil moisture decreases in most areas under the global warming scenario. In this study, we use NCAR Community Land Model version 4 (CLM4) to simulate changes in terrestrial available water (TAW, defined as the precipitation minus evaporation minus runoff, and then divided by the precipitation) under global warming. Preliminary results show that the TAW has clear seasonal variations. Compared to previous studies, which do not include the runoff in the calculations of the available water, our estimates on the TAW has much less available water in high latitudes through out the year, especially under extreme precipitation events.

  19. Spirit's Winter Work Site

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Annotated Version

    This portion of an image acquired by the Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment camera shows the Spirit rover's winter campaign site. Spirit was parked on a slope tilted 11 degrees to the north to maximize sunlight during the southern winter season. 'Tyrone' is an area where the rover's wheels disturbed light-toned soils. Remote sensing and in-situ analyses found the light-toned soil at Tyrone to be sulfate rich and hydrated. The original picture is catalogued as PSP_001513_1655_red and was taken on Sept. 29, 2006.

    NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

  20. Six month-lead downscaling prediction of winter to spring drought in South Korea based on a multimodel ensemble

    NASA Astrophysics Data System (ADS)

    Sohn, Soo-Jin; Ahn, Joong-Bae; Tam, Chi-Yung

    2013-02-01

    Abstract The potential of using a dynamical-statistical method for long-lead drought prediction was investigated. In particular, the APEC Climate Center one-tier multimodel ensemble (MME) was downscaled for predicting the standardized precipitation evapotranspiration index (SPEI) over 60 stations in South Korea. SPEI depends on both precipitation and temperature, and can incorporate the effect of global <span class="hlt">warming</span> on the balance between precipitation and evapotranspiration. It was found that the one-tier MME has difficulty in capturing the local temperature and rainfall variations over extratropical land areas, and has no skill in predicting SPEI during boreal <span class="hlt">winter</span> and spring. On the other hand, temperature and precipitation predictions were substantially improved in the downscaled MME. In conjunction with variance inflation, downscaled MME can give reasonably skillful 6 month-lead forecasts of SPEI for the <span class="hlt">winter</span> to spring period. Our results could lead to more reliable hydrological <span class="hlt">extreme</span> predictions for policymakers and stakeholders in the water management sector, and for better mitigation and climate adaptations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=STS053-97-050&hterms=forgiveness+breakup&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dforgiveness%2Bbreakup','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=STS053-97-050&hterms=forgiveness+breakup&qs=Ntx%3Dmode%2Bmatchany%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dforgiveness%2Bbreakup"><span id="translatedtitle">Breakup of <span class="hlt">Winter</span> Ice Packs, Shantar Island, Sea of Okhotsk, CIS</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1992-01-01</p> <p>The breakup of <span class="hlt">winter</span> ice packs around Shantar Island (55.0N, 138.0E) off the coast of Khabarovsk Kray Oblast, CIS, produced this mosaic of icebergs, bergy bits and growlers in the Sea of Okhotsk as the as an unusual <span class="hlt">warming</span> spell in mid <span class="hlt">winter</span> temporarly melted parts of the sea ice. Oceanographers use these photos to study the interaction of coastal and ocean currents, tides and winds on the movement of ice floes at sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ClDy..tmp..265W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ClDy..tmp..265W"><span id="translatedtitle">Tropospheric circulation during the early twentieth century Arctic <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wegmann, Martin; Brönnimann, Stefan; Compo, Gilbert P.</p> <p>2016-06-01</p> <p>The early twentieth century Arctic <span class="hlt">warming</span> (ETCAW) between 1920 and 1940 is an exceptional feature of climate variability in the last century. Its <span class="hlt">warming</span> rate was only recently matched by recent <span class="hlt">warming</span> in the region. Unlike recent <span class="hlt">warming</span> largely attributable to anthropogenic radiative forcing, atmospheric <span class="hlt">warming</span> during the ETCAW was strongest in the mid-troposphere and is believed to be triggered by an exceptional case of natural climate variability. Nevertheless, ultimate mechanisms and causes for the ETCAW are still under discussion. Here we use state of the art multi-member global circulation models, reanalysis and reconstruction datasets to investigate the internal atmospheric dynamics of the ETCAW. We investigate the role of boreal <span class="hlt">winter</span> mid-tropospheric heat transport and circulation in providing the energy for the large scale <span class="hlt">warming</span>. Analyzing sensible heat flux components and regional differences, climate models are not able to reproduce the heat flux evolution found in reanalysis and reconstruction datasets. These datasets show an increase of stationary eddy heat flux and a decrease of transient eddy heat flux during the ETCAW. Moreover, tropospheric circulation analysis reveals the important role of both the Atlantic and the Pacific sectors in the convergence of southerly air masses into the Arctic during the <span class="hlt">warming</span> event. Subsequently, it is suggested that the internal dynamics of the atmosphere played a major role in the formation in the ETCAW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.6554D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.6554D"><span id="translatedtitle">Changes in annual temperature and precipitation <span class="hlt">extremes</span> in the Carpathians since AD 1961</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dumitrescu, Alexandru; Birsan, Marius-Victor; Magdalena Micu, Dana; Cheval, Sorin</p> <p>2014-05-01</p> <p> high and low elevation areas. The positive shift in the upper tail of summer maximum temperature distribution largely explains the intensification of this signal after mid 1980s or early 1990s, over extended areas within the Carpathian region. The changes in the occurrence of tropical nights are substantial only in low elevation areas (below 700 m) located outside the Carpathian Mountains, which are particularly exposed to persistent and intense <span class="hlt">warm</span> spells in summer. The <span class="hlt">Warm</span> Spell Duration Index is increasing over 60% of the area, showing a coherent pattern related rather to geographical position than to elevation. The shifts in the lower end of minimum temperature distribution suggest a lower frequency of <span class="hlt">extreme</span> cold conditions, favouring an extended increase in the probability of warmer <span class="hlt">winter</span> temperatures. The areas experiencing significant decreases of cold spell duration are rather scattered across the region. The trend patterns are consistent over the region (there are no mixed trends for a given index). Regional differences in climate <span class="hlt">extreme</span> trends within the Carpathian region are related to altitude, rather than latitude. The (annual) East Atlantic pattern shows strong correlations with the <span class="hlt">warm</span>-related indices. Our results are in agreement with previous studies on precipitation and temperature <span class="hlt">extremes</span> in the region. This study has been done within the project CC-WARE (SEE/D/0143/2.1/X).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27145612','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27145612"><span id="translatedtitle">Beyond arctic and alpine: the influence of <span class="hlt">winter</span> climate on temperate ecosystems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ladwig, Laura M; Ratajczak, Zak R; Ocheltree, Troy W; Hafich, Katya A; Churchill, Amber C; Frey, Sarah J K; Fuss, Colin B; Kazanski, Clare E; Muñoz, Juan D; Petrie, Matthew D; Reinmann, Andrew B; Smith, Jane G</p> <p>2016-02-01</p> <p><span class="hlt">Winter</span> climate is expected to change under future climate scenarios, yet the majority of <span class="hlt">winter</span> ecology research is focused in cold-climate ecosystems. In many temperate systems, it is unclear how <span class="hlt">winter</span> climate relates to biotic responses during the growing season. The objective of this study was to examine how <span class="hlt">winter</span> weather relates to plant and animal communities in a variety of terrestrial ecosystems ranging from <span class="hlt">warm</span> deserts to alpine tundra. Specifically, we examined the association between <span class="hlt">winter</span> weather and plant phenology, plant species richness, consumer abundance, and consumer richness in 11 terrestrial ecosystems associated with the U.S. Long-Term Ecological Research (LTER) Network. To varying degrees, <span class="hlt">winter</span> precipitation and temperature were correlated with all biotic response variables. Bud break was tightly aligned with end of <span class="hlt">winter</span> temperatures. For half the sites, <span class="hlt">winter</span> weather was a better predictor of plant species richness than growing season weather. Warmer <span class="hlt">winters</span> were correlated with lower consumer abundances in both temperate and alpine systems. Our findings suggest <span class="hlt">winter</span> weather may have a strong influence on biotic activity during the growing season and should be considered in future studies investigating the effects of climate change on both alpine and temperate systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27145612','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27145612"><span id="translatedtitle">Beyond arctic and alpine: the influence of <span class="hlt">winter</span> climate on temperate ecosystems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ladwig, Laura M; Ratajczak, Zak R; Ocheltree, Troy W; Hafich, Katya A; Churchill, Amber C; Frey, Sarah J K; Fuss, Colin B; Kazanski, Clare E; Muñoz, Juan D; Petrie, Matthew D; Reinmann, Andrew B; Smith, Jane G</p> <p>2016-02-01</p> <p><span class="hlt">Winter</span> climate is expected to change under future climate scenarios, yet the majority of <span class="hlt">winter</span> ecology research is focused in cold-climate ecosystems. In many temperate systems, it is unclear how <span class="hlt">winter</span> climate relates to biotic responses during the growing season. The objective of this study was to examine how <span class="hlt">winter</span> weather relates to plant and animal communities in a variety of terrestrial ecosystems ranging from <span class="hlt">warm</span> deserts to alpine tundra. Specifically, we examined the association between <span class="hlt">winter</span> weather and plant phenology, plant species richness, consumer abundance, and consumer richness in 11 terrestrial ecosystems associated with the U.S. Long-Term Ecological Research (LTER) Network. To varying degrees, <span class="hlt">winter</span> precipitation and temperature were correlated with all biotic response variables. Bud break was tightly aligned with end of <span class="hlt">winter</span> temperatures. For half the sites, <span class="hlt">winter</span> weather was a better predictor of plant species richness than growing season weather. Warmer <span class="hlt">winters</span> were correlated with lower consumer abundances in both temperate and alpine systems. Our findings suggest <span class="hlt">winter</span> weather may have a strong influence on biotic activity during the growing season and should be considered in future studies investigating the effects of climate change on both alpine and temperate systems. PMID:27145612</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26703633','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26703633"><span id="translatedtitle">Role of Acclimatization in Weather-Related Human Mortality During the Transition Seasons of Autumn and Spring in a Thermally <span class="hlt">Extreme</span> Mid-Latitude Continental Climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Freitas, Christopher R; Grigorieva, Elena A</p> <p>2015-12-01</p> <p>Human mortality is closely related to natural climate-determined levels of thermal environmental stress and the resulting thermophysiological strain. Most climate-mortality research has focused on seasonal <span class="hlt">extremes</span> during <span class="hlt">winter</span> and summer when mortality is the highest, while relatively little attention has been paid to mortality during the transitional seasons of autumn and spring. The body acclimatizes to heat in the summer and cold in <span class="hlt">winter</span> and readjusts through acclimatization during the transitions between the two during which time the body experiences the thermophysiological strain of readjustment. To better understand the influences of weather on mortality through the acclimatization process, the aim here is to examine the periods that link very cold and very <span class="hlt">warms</span> seasons. The study uses the Acclimatization Thermal Strain Index (ATSI), which is a comparative measure of short-term thermophysiological impact on the body. ATSI centers on heat exchange with the body’s core via the respiratory system, which cannot be protected. The analysis is based on data for a major city in the climatic region of the Russian Far East characterized by very hot summers and <span class="hlt">extremely</span> cold <span class="hlt">winters</span>. The results show that although mortality peaks in <span class="hlt">winter</span> (January) and is at its lowest in summer (August), there is not a smooth rise through autumn nor a smooth decline through spring. A secondary peak occurs in autumn (October) with a smaller jump in May. This suggests the acclimatization from <span class="hlt">warm</span>-to-cold produces more thermophysiological strain than the transition from cold-to-<span class="hlt">warm</span>. The study shows that ATSI is a useful metric for quantifying the extent to which biophysical adaptation plays a role in increased strain on the body during re-acclimatization and for this reason is a more appropriate climatic indictor than air temperature alone. The work gives useful bioclimatic information on risks involved in transitional seasons in regions characterized by climatic <span class="hlt">extremes</span>. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26703633','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26703633"><span id="translatedtitle">Role of Acclimatization in Weather-Related Human Mortality During the Transition Seasons of Autumn and Spring in a Thermally <span class="hlt">Extreme</span> Mid-Latitude Continental Climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Freitas, Christopher R; Grigorieva, Elena A</p> <p>2015-11-26</p> <p>Human mortality is closely related to natural climate-determined levels of thermal environmental stress and the resulting thermophysiological strain. Most climate-mortality research has focused on seasonal <span class="hlt">extremes</span> during <span class="hlt">winter</span> and summer when mortality is the highest, while relatively little attention has been paid to mortality during the transitional seasons of autumn and spring. The body acclimatizes to heat in the summer and cold in <span class="hlt">winter</span> and readjusts through acclimatization during the transitions between the two during which time the body experiences the thermophysiological strain of readjustment. To better understand the influences of weather on mortality through the acclimatization process, the aim here is to examine the periods that link very cold and very <span class="hlt">warms</span> seasons. The study uses the Acclimatization Thermal Strain Index (ATSI), which is a comparative measure of short-term thermophysiological impact on the body. ATSI centers on heat exchange with the body’s core via the respiratory system, which cannot be protected. The analysis is based on data for a major city in the climatic region of the Russian Far East characterized by very hot summers and <span class="hlt">extremely</span> cold <span class="hlt">winters</span>. The results show that although mortality peaks in <span class="hlt">winter</span> (January) and is at its lowest in summer (August), there is not a smooth rise through autumn nor a smooth decline through spring. A secondary peak occurs in autumn (October) with a smaller jump in May. This suggests the acclimatization from <span class="hlt">warm</span>-to-cold produces more thermophysiological strain than the transition from cold-to-<span class="hlt">warm</span>. The study shows that ATSI is a useful metric for quantifying the extent to which biophysical adaptation plays a role in increased strain on the body during re-acclimatization and for this reason is a more appropriate climatic indictor than air temperature alone. The work gives useful bioclimatic information on risks involved in transitional seasons in regions characterized by climatic <span class="hlt">extremes</span>. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4690898','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4690898"><span id="translatedtitle">Role of Acclimatization in Weather-Related Human Mortality During the Transition Seasons of Autumn and Spring in a Thermally <span class="hlt">Extreme</span> Mid-Latitude Continental Climate</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>de Freitas, Christopher R.; Grigorieva, Elena A.</p> <p>2015-01-01</p> <p>Human mortality is closely related to natural climate-determined levels of thermal environmental stress and the resulting thermophysiological strain. Most climate-mortality research has focused on seasonal <span class="hlt">extremes</span> during <span class="hlt">winter</span> and summer when mortality is the highest, while relatively little attention has been paid to mortality during the transitional seasons of autumn and spring. The body acclimatizes to heat in the summer and cold in <span class="hlt">winter</span> and readjusts through acclimatization during the transitions between the two during which time the body experiences the thermophysiological strain of readjustment. To better understand the influences of weather on mortality through the acclimatization process, the aim here is to examine the periods that link very cold and very <span class="hlt">warms</span> seasons. The study uses the Acclimatization Thermal Strain Index (ATSI), which is a comparative measure of short-term thermophysiological impact on the body. ATSI centers on heat exchange with the body’s core via the respiratory system, which cannot be protected. The analysis is based on data for a major city in the climatic region of the Russian Far East characterized by very hot summers and <span class="hlt">extremely</span> cold <span class="hlt">winters</span>. The results show that although mortality peaks in <span class="hlt">winter</span> (January) and is at its lowest in summer (August), there is not a smooth rise through autumn nor a smooth decline through spring. A secondary peak occurs in autumn (October) with a smaller jump in May. This suggests the acclimatization from <span class="hlt">warm</span>-to-cold produces more thermophysiological strain than the transition from cold-to-<span class="hlt">warm</span>. The study shows that ATSI is a useful metric for quantifying the extent to which biophysical adaptation plays a role in increased strain on the body during re-acclimatization and for this reason is a more appropriate climatic indictor than air temperature alone. The work gives useful bioclimatic information on risks involved in transitional seasons in regions characterized by climatic <span class="hlt">extremes</span>. This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AtmRe.127..195D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AtmRe.127..195D"><span id="translatedtitle">Recent changes in daily precipitation and surface air temperature <span class="hlt">extremes</span> in mainland Portugal, in the period 1941-2007</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Lima, M. Isabel P.; Santo, Fátima Espírito; Ramos, Alexandre M.; de Lima, João L. M. P.</p> <p>2013-06-01</p> <p>Changes in the climatology of precipitation and surface air temperature are being investigated worldwide, searching for changes in variability, the mean and <span class="hlt">extreme</span> events (maximum and minimum). By exploring recent adjustments in the climate of mainland Portugal, particularly in the intensity, frequency and duration of <span class="hlt">extreme</span> events, this study investigates trends in selected specific indices that are calculated from daily precipitation data from 57 and surface air temperature data from 23 measuring stations scattered across the territory. Special attention is paid to regional differences and variations in seasonality. The data cover the periods 1941-2007 for precipitation, and 1941-2006 for temperature. They are explored at the annual and seasonal scales and for different sub-periods. Results show that trends in annual precipitation indices are generally weak and, overall, not statistically significant at the 5% level. Nevertheless, a decreasing trend is revealed by regional indices of total wet-day precipitation and <span class="hlt">extreme</span> precipitation (above the 99th percentile). Seasonal precipitation exhibits significant decreasing trends in spring precipitation, while <span class="hlt">extreme</span> heavy precipitation events, in terms of both magnitude and frequency, have become more pronounced in autumn. Results for <span class="hlt">winter</span> and summer suggest that the <span class="hlt">extremes</span> have not suffered any significant aggravation. Trends for air temperature are statistically more significant and marked than for precipitation and indicate general <span class="hlt">warming</span> across the territory. This <span class="hlt">warming</span> trend is revealed very consistently by the time series of individual stations and regional mean temperature, and is also consistent with the findings reported in other studies for Portugal and at the European scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988EOSTr..69..820W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988EOSTr..69..820W"><span id="translatedtitle">Model predicts global <span class="hlt">warming</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wainger, Lisa A.</p> <p></p> <p>Global greenhouse <span class="hlt">warming</span> will be clearly identifiable by the 1990s, according to eight scientists who have been studying climate changes using computer models. Researchers at NASA's Goddard Space Flight Center, Goddard Institute for Space Studies, New York, and the Massachusetts Institute of Technology, Cambridge, say that by the 2010s, most of the globe will be experiencing “substantial” <span class="hlt">warming</span>. The level of <span class="hlt">warming</span> will depend on amounts of trace gases, or greenhouse gases, in the atmosphere.Predictions for the next 70 years are based on computer simulations of Earth's climate. In three runs of the model, James Hansen and his colleagues looked at the effects of changing amounts of atmospheric gases with time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22695877','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22695877"><span id="translatedtitle">Global <span class="hlt">warming</span> and allergy in Asia Minor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bajin, Munir Demir; Cingi, Cemal; Oghan, Fatih; Gurbuz, Melek Kezban</p> <p>2013-01-01</p> <p>The earth is <span class="hlt">warming</span>, and it is <span class="hlt">warming</span> quickly. Epidemiological studies have demonstrated that global <span class="hlt">warming</span> is correlated with the frequency of pollen-induced respiratory allergy and allergic diseases. There is a body of evidence suggesting that the prevalence of allergic diseases induced by pollens is increasing in developed countries, a trend that is also evident in the Mediterranean area. Because of its mild <span class="hlt">winters</span> and sunny days with dry summers, the Mediterranean area is different from the areas of central and northern Europe. Classical examples of allergenic pollen-producing plants of the Mediterranean climate include Parietaria, Olea and Cupressaceae. Asia Minor is a Mediterranean region that connects Asia and Europe, and it includes considerable coastal areas. Gramineae pollens are the major cause of seasonal allergic rhinitis in Asia Minor, affecting 1.3-6.4 % of the population, in accordance with other European regions. This article emphasizes the importance of global climate change and anticipated increases in the prevalence and severity of allergic disease in Asia Minor, mediated through worsening air pollution and altered local and regional pollen production, from an otolaryngologic perspective.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1817150I&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..1817150I&link_type=ABSTRACT"><span id="translatedtitle">Seasonal Forecasts for Northern Hemisphere <span class="hlt">Winter</span> 2015/16</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ineson, Sarah; Scaife, Adam; Comer, Ruth; Dunstone, Nick; Fereday, David; Folland, Chris; Gordon, Margaret; Karpechko, Alexey; Knight, Jeff; MacLachlan, Craig; Smith, Doug; Walker, Brent</p> <p>2016-04-01</p> <p>The northern <span class="hlt">winter</span> of 2015/16 gave rise to the strongest El Niño event since 1997/8. Central and eastern Pacific sea surface temperature anomalies exceeded three degrees and closely resembled the strong El Niño in <span class="hlt">winter</span> of 1982/3. A second feature of this <span class="hlt">winter</span> was a strong westerly phase of the Quasi-Biennial Oscillation and very strong winds in the stratospheric polar night jet. At the surface, intense extratropical circulation anomalies occurred in both the North Pacific and North Atlantic that were consistent with known teleconnections to the observed phases of ENSO and the QBO. The North Atlantic Oscillation was very positive in the early <span class="hlt">winter</span> period (Nov-Dec) and was more blocked in the late <span class="hlt">winter</span>. Initialised climate predictions were able to capture these signals at seasonal lead times. This case study adds to the evidence that north Atlantic circulation exhibits predictability on seasonal timescales, and in this case we show that even aspects of the detailed pattern and sub-seasonal evolution were predicted, providing warning of increased risk of <span class="hlt">extreme</span> events such as the intense rainfall which caused <span class="hlt">extreme</span> flooding in the UK in December.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6395050','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6395050"><span id="translatedtitle"><span class="hlt">Winter</span> fuels report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1990-11-29</p> <p>The <span class="hlt">Winter</span> Fuels Report is intended to provide concise, timely information to the industry, the press, policymakers, consumers, analysts, and state and local governments on the following topics: distillate fuel oil net production, imports and stocks for all PADD's and product supplied on a US level; propane net product supplied on a US level; propane net production, imports and stocks for Petroleum Administration for Defense Districts (PADD) I, II, and III; natural gas supply and disposition and underground storage for the United States and consumption for all PADD's; residential and wholesale pricing data for propane and heating oil for those states participating in the joint Energy Information Administration (EIA)/State Heating Oil and Propane Program; crude oil and petroleum price comparisons for the United States and selected cities; and US total heating degree-days by city. 27 figs, 12 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=PIA05690&hterms=Utopia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DUtopia','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=PIA05690&hterms=Utopia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DUtopia"><span id="translatedtitle"><span class="hlt">Winter</span> Clouds Over Mie</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>12 March 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image shows late <span class="hlt">winter</span> clouds over the 104 km (65 mi) diameter crater, Mie. Cellular clouds occur in the lower martian atmosphere, surrounding Mie Crater. Their cloudtops are at an altitude that is below the crater rim. Higher than the crater rim occurs a series of lee wave clouds, indicating air circulation moving from west/northwest (left) toward the east/southeast (right). Mie Crater is located in Utopia Planitia, not too far from the Viking 2 landing site, near 48.5 N, 220.4 W. Sunlight illuminates this January 2004 scene from the lower left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25712272','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25712272"><span id="translatedtitle">Ice cover extent drives phytoplankton and bacterial community structure in a large north-temperate lake: implications for a <span class="hlt">warming</span> climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beall, B F N; Twiss, M R; Smith, D E; Oyserman, B O; Rozmarynowycz, M J; Binding, C E; Bourbonniere, R A; Bullerjahn, G S; Palmer, M E; Reavie, E D; Waters, Lcdr M K; Woityra, Lcdr W C; McKay, R M L</p> <p>2016-06-01</p> <p>Mid-<span class="hlt">winter</span> limnological surveys of Lake Erie captured <span class="hlt">extremes</span> in ice extent ranging from expansive ice cover in 2010 and 2011 to nearly ice-free waters in 2012. Consistent with a <span class="hlt">warming</span> climate, ice cover on the Great Lakes is in decline, thus the ice-free condition encountered may foreshadow the lakes future <span class="hlt">winter</span> state. Here, we show that pronounced changes in annual ice cover are accompanied by equally important shifts in phytoplankton and bacterial community structure. Expansive ice cover supported phytoplankton blooms of filamentous diatoms. By comparison, ice free conditions promoted the growth of smaller sized cells that attained lower total biomass. We propose that isothermal mixing and elevated turbidity in the absence of ice cover resulted in light limitation of the phytoplankton during <span class="hlt">winter</span>. Additional insights into microbial community dynamics were gleaned from short 16S rRNA tag (Itag) Illumina sequencing. UniFrac analysis of Itag sequences showed clear separation of microbial communities related to presence or absence of ice cover. Whereas the ecological implications of the changing bacterial community are unclear at this time, it is likely that the observed shift from a phytoplankton community dominated by filamentous diatoms to smaller cells will have far reaching ecosystem effects including food web disruptions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20715613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20715613"><span id="translatedtitle"><span class="hlt">Winter</span> climate change: a critical factor for temperate vegetation performance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kreyling, Juergen</p> <p>2010-07-01</p> <p><span class="hlt">Winter</span> ecological processes are important drivers of vegetation and ecosystem functioning in temperate ecosystems. There, <span class="hlt">winter</span> conditions are subject to rapid climate change. The potential loss of a longer-lasting snow cover with implications to other plant-related climate parameters and overwintering strategies make the temperate zone particularly vulnerable to <span class="hlt">winter</span> climate change. A formalized literature search in the ISI Web of Science shows that plant related research on the effects of <span class="hlt">winter</span> climate change is generally underrepresented. Temperate regions in particular are rarely studied in this respect, although the few existing studies imply strong effects of <span class="hlt">winter</span> climate change on species ranges, species compositions, phenology, or frost injury. The generally positive effect of <span class="hlt">warming</span> on plant survival and production may be counteracted by effects such as an increased frost injury of roots and shoots, an increased insect pest risk, or a disrupted synchrony between plants and pollinators. Based on the literature study, gaps in current knowledge are discussed. Understanding the relative effects of interacting climate parameters, as well as a stronger consideration of shortterm events and variability of climatic conditions is urgent. With respect to plant response, it would be particularly worthwhile to account for hidden players such as pathogens, pollinators, herbivores, or fungal partners in mycorrhization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20715613','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20715613"><span id="translatedtitle"><span class="hlt">Winter</span> climate change: a critical factor for temperate vegetation performance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kreyling, Juergen</p> <p>2010-07-01</p> <p><span class="hlt">Winter</span> ecological processes are important drivers of vegetation and ecosystem functioning in temperate ecosystems. There, <span class="hlt">winter</span> conditions are subject to rapid climate change. The potential loss of a longer-lasting snow cover with implications to other plant-related climate parameters and overwintering strategies make the temperate zone particularly vulnerable to <span class="hlt">winter</span> climate change. A formalized literature search in the ISI Web of Science shows that plant related research on the effects of <span class="hlt">winter</span> climate change is generally underrepresented. Temperate regions in particular are rarely studied in this respect, although the few existing studies imply strong effects of <span class="hlt">winter</span> climate change on species ranges, species compositions, phenology, or frost injury. The generally positive effect of <span class="hlt">warming</span> on plant survival and production may be counteracted by effects such as an increased frost injury of roots and shoots, an increased insect pest risk, or a disrupted synchrony between plants and pollinators. Based on the literature study, gaps in current knowledge are discussed. Understanding the relative effects of interacting climate parameters, as well as a stronger consideration of shortterm events and variability of climatic conditions is urgent. With respect to plant response, it would be particularly worthwhile to account for hidden players such as pathogens, pollinators, herbivores, or fungal partners in mycorrhization. PMID:20715613</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18240681','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18240681"><span id="translatedtitle">Temperature-associated dynamics of songbird <span class="hlt">winter</span> distributions and abundances.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Butler, J Russell; MacMynowski, Dena P; Laurent, Chad; Root, Terry L</p> <p>2007-12-01</p> <p>Using Christmas Bird Count data, we analyze the annual spatio-temporal abundances of six passerine species in the upper Great Plains, US (1960-1990). This study provides new insight into how global <span class="hlt">warming</span> could cause separation of species within present-day communities. We find that <span class="hlt">winter</span> relative abundances of similarly-sized songbirds are differentially affected by ambient <span class="hlt">winter</span> temperature. As such, average annual <span class="hlt">winter</span> temperature fluctuations (i.e., severity of <span class="hlt">winter</span>) are significantly (P < 0.05) correlated with the relative abundances of three species while the other three are not. Our conditional probability-of-occurrence analysis indicates that the abundances of the three temperature-associated species declined markedly below -4 degrees C while the abundances of the other three species fluctuated little from 8 degrees C to -16 degrees C. We conclude that even in colder climates i) the <span class="hlt">winter</span> distributions of some, but not all, songbirds are directly or indirectly limited by temperature; and ii) these birds have dynamic abundances that can quickly respond to temperature changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6515033','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6515033"><span id="translatedtitle"><span class="hlt">Winter</span> movements of four fish species near a thermal plume in northern Minnesota</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ross, M.J.; Winter, J.D.</p> <p>1981-01-01</p> <p>Four fish species were studied during the <span class="hlt">winter</span> of 1975 to compare their <span class="hlt">winter</span> movements near the thermal plume of a power plant. Seventeen yellow perch (Perca flavescens), six northern pike (Esox lucius), three walleyes (Stizostedion vitreum), and two largemouth bass (Micropterus salmoides) were equipped with radio frequency transmitters. The spatial distributions differed among species. Only the largemouth bass confined their movements to heated water areas. The yellow perch, which was of particular interest, do not seem to be attracted to <span class="hlt">warm</span> <span class="hlt">winter</span> waters, and thus locate themselves in the peripheral areas of the discharge bay and fail to reproduce. This finding is contrary to those of previous studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100009654','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100009654"><span id="translatedtitle">Liquid Cooling/<span class="hlt">Warming</span> Garment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koscheyev, Victor S.; Leon, Gloria R.; Dancisak, Michael J.</p> <p>2010-01-01</p> <p>The NASA liquid cooling/ventilating garment (LCVG) currently in use was developed over 40 years ago. With the commencement of a greater number of extra-vehicular activity (EVA) procedures with the construction of the International Space Station, problems of astronaut comfort, as well as the reduction of the consumption of energy, became more salient. A shortened liquid cooling/<span class="hlt">warming</span> garment (SLCWG) has been developed based on physiological principles comparing the efficacy of heat transfer of different body zones; the capability of blood to deliver heat; individual muscle and fat body composition as a basis for individual thermal profiles to customize the zonal sections of the garment; and the development of shunts to minimize or redirect the cooling/<span class="hlt">warming</span> loop for different environmental conditions, physical activity levels, and emergency situations. The SLCWG has been designed and completed, based on extensive testing in rest, exercise, and antiorthostatic conditions. It is more energy efficient than the LCVG currently used by NASA. The total length of tubing in the SLCWG is approximately 35 percent less and the weight decreased by 20 percent compared to the LCVG. The novel features of the innovation are: 1. The efficiency of the SLCWG to maintain thermal status under <span class="hlt">extreme</span> changes in body surface temperatures while using significantly less tubing than the LCVG. 2. The construction of the garment based on physiological principles of heat transfer. 3. The identification of the body areas that are most efficient in heat transfer. 4. The inclusion of a hood as part of the garment. 5. The lesser consumption of energy.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27538725','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27538725"><span id="translatedtitle">Desert Amplification in a <span class="hlt">Warming</span> Climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Liming</p> <p>2016-01-01</p> <p>Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950-2099 by large-scale ecoregion and find strongest <span class="hlt">warming</span> consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a <span class="hlt">warming</span> climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global <span class="hlt">warming</span> associated with water vapor feedbacks over land in low- and mid- latitudes where surface <span class="hlt">warming</span> rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus <span class="hlt">extremely</span> sensitive to changes of water vapor. PMID:27538725</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27538725','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27538725"><span id="translatedtitle">Desert Amplification in a <span class="hlt">Warming</span> Climate.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Liming</p> <p>2016-08-19</p> <p>Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950-2099 by large-scale ecoregion and find strongest <span class="hlt">warming</span> consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a <span class="hlt">warming</span> climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global <span class="hlt">warming</span> associated with water vapor feedbacks over land in low- and mid- latitudes where surface <span class="hlt">warming</span> rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus <span class="hlt">extremely</span> sensitive to changes of water vapor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4990907','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4990907"><span id="translatedtitle">Desert Amplification in a <span class="hlt">Warming</span> Climate</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhou, Liming</p> <p>2016-01-01</p> <p>Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950–2099 by large-scale ecoregion and find strongest <span class="hlt">warming</span> consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a <span class="hlt">warming</span> climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global <span class="hlt">warming</span> associated with water vapor feedbacks over land in low- and mid- latitudes where surface <span class="hlt">warming</span> rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus <span class="hlt">extremely</span> sensitive to changes of water vapor. PMID:27538725</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...631065Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...631065Z"><span id="translatedtitle">Desert Amplification in a <span class="hlt">Warming</span> Climate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Liming</p> <p>2016-08-01</p> <p>Here I analyze the observed and projected surface temperature anomalies over land between 50°S-50°N for the period 1950–2099 by large-scale ecoregion and find strongest <span class="hlt">warming</span> consistently and persistently seen over driest ecoregions such as the Sahara desert and the Arabian Peninsula during various 30-year periods, pointing to desert amplification in a <span class="hlt">warming</span> climate. This amplification enhances linearly with the global mean greenhouse gases(GHGs) radiative forcing and is attributable primarily to a stronger GHGs-enhanced downward longwave radiation forcing reaching the surface over drier ecoregions as a consequence of a warmer and thus moister atmosphere in response to increasing GHGs. These results indicate that desert amplification may represent a fundamental pattern of global <span class="hlt">warming</span> associated with water vapor feedbacks over land in low- and mid- latitudes where surface <span class="hlt">warming</span> rates depend inversely on ecosystem dryness. It is likely that desert amplification might involve two types of water vapor feedbacks that maximize respectively in the tropical upper troposphere and near the surface over deserts, with both being very dry and thus <span class="hlt">extremely</span> sensitive to changes of water vapor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=mural&pg=3&id=EJ1002704','ERIC'); return false;" href="http://eric.ed.gov/?q=mural&pg=3&id=EJ1002704"><span id="translatedtitle"><span class="hlt">Warm</span> and Cool Cityscapes</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Jubelirer, Shelly</p> <p>2012-01-01</p> <p>Painting cityscapes is a great way to teach first-grade students about <span class="hlt">warm</span> and cool colors. Before the painting begins, the author and her class have an in-depth discussion about big cities and what types of buildings or structures that might be seen in them. They talk about large apartment and condo buildings, skyscrapers, art museums,…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121.9441G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121.9441G"><span id="translatedtitle">Interannual modulation of East African early short rains by the <span class="hlt">winter</span> Arctic Oscillation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gong, Dao-Yi; Guo, Dong; Mao, Rui; Yang, Jing; Gao, Yongqi; Kim, Seong-Joong</p> <p>2016-08-01</p> <p>In the present study, we analyzed the interannual linkage between the boreal <span class="hlt">winter</span> Arctic Oscillation (AO) and East African early short rains. When the Indian Ocean Dipole and El Niño-Southern Oscillation variance are excluded by linear regression, the boreal <span class="hlt">winter</span> AO index is significantly correlated with the October East African precipitation over the domain of 5°N-5°S and 35°-45°E for the period 1979-2014, r =+ 0.46. The upper ocean heat content likely acts as a medium that links the AO and East African precipitation. Significant subsurface <span class="hlt">warming</span> and positive upper ocean heat content anomalies occur over the western Indian Ocean during the autumn following positive AO <span class="hlt">winters</span>, which enriches the atmospheric moisture, intensifies convection, and enhances precipitation. Oceanic dynamics play a key role in causing this subsurface <span class="hlt">warming</span>. <span class="hlt">Winter</span> AO-related atmospheric circulation creates anomalous wind stress, which forces a downwelling oceanic Rossby wave between 60°-75°E and 5°-10°S, where the thermocline significantly deepens. This Rossby wave propagates westward and accompanies significant subsurface <span class="hlt">warming</span> along the thermocline. The Rossby wave arrives at the western Indian Ocean in the late summer, significantly <span class="hlt">warming</span> the region to the west of 55°E at a depth of 60-100 m. This <span class="hlt">warming</span> remains significant through October. Correspondingly, the upper ocean heat content significantly increases by approximately 2-3 × 108 J m-2 in the region west of 60°E between 5° and 10°S. The role of these oceanic dynamics in linking the <span class="hlt">winter</span> AO, and anomalous subsurface <span class="hlt">warming</span> was tested by numerical experiments with an oceanic general circulation model. The experiments were performed with the forcing of AO-related wind stress anomalies over the Indian Ocean in the <span class="hlt">winter</span>. The oceanic Rossby wave generated in the central Indian Ocean during boreal <span class="hlt">winter</span>, the consequent subsurface <span class="hlt">warming</span>, and the anomalous upper ocean heat content in October over the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015STP.....1d..47P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015STP.....1d..47P"><span id="translatedtitle">Ionospheric reaction on sudden stratospheric <span class="hlt">warming</span> events in Russiás Asia region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Polyakova, Anna; Perevalova, Natalya; Chernigovskaya, Marina</p> <p>2015-12-01</p> <p>The response of the ionosphere to sudden stratospheric <span class="hlt">warmings</span> (SSWs) in the Asian region of Russia is studied. Two SSW events observed in 2008-2009 and 2012-2013 <span class="hlt">winter</span> periods of <span class="hlt">extreme</span> solar minimum and moderate solar maximum are considered. To detect the ionospheric effects caused by SSWs, we carried out a joint analysis of global ionospheric maps (GIM) of the total electron content (TEC), MLS (Microwave Limb Sounder, EOS Aura) measurements of temperature vertical profiles, as well as NCEP/NCAR and UKMO Reanalysis data. For the first time, it was found that during strong SSWs, in the mid-latitude ionosphere the amplitude of diurnal TEC variation decreases nearly half compared to quiet days. At the same time, the intensity of TEC deviations from the background level increases. It was also found that at SSW peak the midday TEC maximum decreases, and night/morning TEC values increase compared to quiet days. It was shown that during SSWs, TEC dynamics was identical for different geophysical conditions.The response of the ionosphere to sudden stratospheric <span class="hlt">warmings</span> (SSWs) in the Asian region of Russia is studied. Two SSW events observed in 2008-2009 and 2012-2013 <span class="hlt">winter</span> periods of <span class="hlt">extreme</span> solar minimum and moderate solar maximum are considered. To detect the ionospheric effects caused by SSWs, we carried out a joint analysis of global ionospheric maps (GIM) of the total electron content (TEC), MLS (Microwave Limb Sounder, EOS Aura) measurements of temperature vertical profiles, as well as NCEP/NCAR and UKMO Reanalysis data. For the first time, it was found that during strong SSWs, in the mid-latitude ionosphere the amplitude of diurnal TEC variation decreases nearly half compared to quiet days. At the same time, the intensity of TEC deviations from the background level increases. It was also found that at SSW peak the midday TEC maximum decreases, and night/morning TEC values increase compared to quiet days. It was shown that during SSWs, TEC dynamics was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ThApC.119..229Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ThApC.119..229Z"><span id="translatedtitle">Interannual variability of <span class="hlt">winter</span> precipitation in Southeast China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Ling; Fraedrich, Klaus; Zhu, Xiuhua; Sielmann, Frank; Zhi, Xiefei</p> <p>2015-01-01</p> <p>The observed <span class="hlt">winter</span> (DJF) precipitation in Southeast China (1961-2010) is characterized by a monopole pattern of the 3-monthly Standardized Precipitation Index (SPI-3) whose interannual variability is related to the anomalies of East Asian <span class="hlt">Winter</span> Monsoon (EAWM) systems. Dynamic composites and linear regression analysis indicate that the intensity of EAWM and Siberia High (SH), the position of East Asian Trough (EAT), and El Niño events and sea surface temperature (SST) anomalies over South China Sea (SCS) influence different regions of anomalous Southeast China <span class="hlt">winter</span> precipitation on interannual scales. The circulation indices (EAWM index, SH index, and EAT index) mainly affect the <span class="hlt">winter</span> precipitation in the eastern part of Southeast China. El Niño events affect the South China <span class="hlt">winter</span> precipitation due to the anticyclone anomalies over Philippines. The effect of SCS SST anomalies on the <span class="hlt">winter</span> precipitation is mainly in the southern part of Yangtze River. Thus, a set of circulation regimes, represented by a handful indices, provide the basis for modeling precipitation anomalies or <span class="hlt">extremes</span> in future climate projections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H42D..06D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H42D..06D"><span id="translatedtitle">Anthropogenic <span class="hlt">Warming</span> Has Increased Drought Risk In California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diffenbaugh, N. S.; Swain, D. L.; Touma, D. E.</p> <p>2015-12-01</p> <p>California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo precipitation, the highest annual temperature, and the most <span class="hlt">extreme</span> drought indicators on record. The <span class="hlt">extremely</span> <span class="hlt">warm</span> and dry conditions have led to acute water shortages, groundwater overdraft, critically low streamflow, and enhanced wildfire risk. Analyzing historical climate observations from California, we find that precipitation deficits in California were more than twice as likely to yield drought years if they occurred when conditions were <span class="hlt">warm</span>. We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with <span class="hlt">warm</span> conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also <span class="hlt">warm</span>. Further, a large ensemble of climate model realizations reveals that additional global <span class="hlt">warming</span> over the next few decades is very likely to create ˜100% probability that any annual-scale dry period is also <span class="hlt">extremely</span> <span class="hlt">warm</span>. We therefore conclude that anthropogenic <span class="hlt">warming</span> is increasing the probability of co-occurring <span class="hlt">warm</span>-dry conditions like those that have created the acute human and ecosystem impacts associated with the "exceptional" 2012-2014 drought in California.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25733875','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25733875"><span id="translatedtitle">Anthropogenic <span class="hlt">warming</span> has increased drought risk in California.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Diffenbaugh, Noah S; Swain, Daniel L; Touma, Danielle</p> <p>2015-03-31</p> <p>California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo precipitation, the highest annual temperature, and the most <span class="hlt">extreme</span> drought indicators on record. The <span class="hlt">extremely</span> <span class="hlt">warm</span> and dry conditions have led to acute water shortages, groundwater overdraft, critically low streamflow, and enhanced wildfire risk. Analyzing historical climate observations from California, we find that precipitation deficits in California were more than twice as likely to yield drought years if they occurred when conditions were <span class="hlt">warm</span>. We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with <span class="hlt">warm</span> conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also <span class="hlt">warm</span>. Further, a large ensemble of climate model realizations reveals that additional global <span class="hlt">warming</span> over the next few decades is very likely to create ∼ 100% probability that any annual-scale dry period is also <span class="hlt">extremely</span> <span class="hlt">warm</span>. We therefore conclude that anthropogenic <span class="hlt">warming</span> is increasing the probability of co-occurring <span class="hlt">warm</span>-dry conditions like those that have created the acute human and ecosystem impacts associated with the "exceptional" 2012-2014 drought in California.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25733875','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25733875"><span id="translatedtitle">Anthropogenic <span class="hlt">warming</span> has increased drought risk in California.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Diffenbaugh, Noah S; Swain, Daniel L; Touma, Danielle</p> <p>2015-03-31</p> <p>California is currently in the midst of a record-setting drought. The drought began in 2012 and now includes the lowest calendar-year and 12-mo precipitation, the highest annual temperature, and the most <span class="hlt">extreme</span> drought indicators on record. The <span class="hlt">extremely</span> <span class="hlt">warm</span> and dry conditions have led to acute water shortages, groundwater overdraft, critically low streamflow, and enhanced wildfire risk. Analyzing historical climate observations from California, we find that precipitation deficits in California were more than twice as likely to yield drought years if they occurred when conditions were <span class="hlt">warm</span>. We find that although there has not been a substantial change in the probability of either negative or moderately negative precipitation anomalies in recent decades, the occurrence of drought years has been greater in the past two decades than in the preceding century. In addition, the probability that precipitation deficits co-occur with <span class="hlt">warm</span> conditions and the probability that precipitation deficits produce drought have both increased. Climate model experiments with and without anthropogenic forcings reveal that human activities have increased the probability that dry precipitation years are also <span class="hlt">warm</span>. Further, a large ensemble of climate model realizations reveals that additional global <span class="hlt">warming</span> over the next few decades is very likely to create ∼ 100% probability that any annual-scale dry period is also <span class="hlt">extremely</span> <span class="hlt">warm</span>. We therefore conclude that anthropogenic <span class="hlt">warming</span> is increasing the probability of co-occurring <span class="hlt">warm</span>-dry conditions like those that have created the acute human and ecosystem impacts associated with the "exceptional" 2012-2014 drought in California. PMID:25733875</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7262155','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/7262155"><span id="translatedtitle">Polar <span class="hlt">warming</span> in the middle atmosphere of Mars</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Deming, D.; Mumma, M.J.; Espenak, F.; Kostiuk, T.; Zipoy, D.</p> <p>1986-05-01</p> <p>During the 1984 Mars opposition, ground-based laser heterodyne spectroscopy was obtained for the nonthermal core emission of the 10.33-micron R(8) and 10.72-micron P(32) lines of C-12(O-16)2 at 23 locations on the Martian disk. It is deduced on the basis of these data that the temperature of the middle Martian atmosphere varies with latitude, and a meridional gradient of 0.4-0.9 K/deg latitude is indicated. The highest temperatures are noted to lie at high latitudes in the <span class="hlt">winter</span> hemisphere; as in the terrestrial case of seasonal effects at the menopause, this <span class="hlt">winter</span> polar <span class="hlt">warming</span> in the Martian middle atmosphere requires departures from radiative equilibrium. Two-dimensional circulation model comparisons with these results indicate that atmospheric dust may enhance this dynamical heating at high <span class="hlt">winter</span> latitudes. 43 references.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986Icar...66..366D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986Icar...66..366D"><span id="translatedtitle">Polar <span class="hlt">warming</span> in the middle atmosphere of Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deming, D.; Mumma, M. J.; Espenak, F.; Kostiuk, T.; Zipoy, D.</p> <p>1986-05-01</p> <p>During the 1984 Mars opposition, ground-based laser heterodyne spectroscopy was obtained for the nonthermal core emission of the 10.33-micron R(8) and 10.72-micron P(32) lines of C-12(O-16)2 at 23 locations on the Martian disk. It is deduced on the basis of these data that the temperature of the middle Martian atmosphere varies with latitude, and a meridional gradient of 0.4-0.9 K/deg latitude is indicated. The highest temperatures are noted to lie at high latitudes in the <span class="hlt">winter</span> hemisphere; as in the terrestrial case of seasonal effects at the menopause, this <span class="hlt">winter</span> polar <span class="hlt">warming</span> in the Martian middle atmosphere requires departures from radiative equilibrium. Two-dimensional circul