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Sample records for inter annual patterns

  1. Seasonal and inter-annual snowmelt patterns in the southern Sierra Nevada, California

    NASA Astrophysics Data System (ADS)

    Musselman, K. N.; Molotch, N. P.; Margulis, S. A.

    2012-12-01

    In the Sierra Nevada, seasonal snow represents a critical component of California's water resource infrastructure in that it affords reliable water during otherwise arid summers. Complex spatial, seasonal and inter-annual snowmelt patterns determine when and where that meltwater is available. Our knowledge of snowmelt dynamics is typically limited to what we can infer from sparse, point-scale snow measurement stations. Limitations such as these motivate the use of numerical snowmelt models. We evaluate the ability of the Alpine3D model system to represent three years of snow dynamics over an 1800 km2 area of Sequoia National Park. The domain spans a 3600 m elevation gradient and ecosystems ranging from semi-arid grasslands to massive sequoia stands to alpine tundra. The model results were evaluated against data from a multi-scale measurement campaign that included airborne LiDAR, clusters of snow depth sensors, repeated manual snow surveys, and automated SWE stations. Compared to these measurements, Alpine3D consistently performed well in middle elevation conifer forests; compared to LiDAR data, the mean snow depth error in forested regions was < 2%. The model also simulated the snow disappearance date within two days of that measured by regional automated sensors. At upper elevations, however, the model tended to overestimate SWE by 50% to as much as 100% in some areas and the errors were linearly correlated (R2 > 0.80, p<0.01) with the distance of the SWE measurements from the nearest precipitation gauge used to derive the model forcing. The results suggest that Alpine3D is highly accurate during the melt season and that precipitation uncertainty may be a critical limitation on snow model accuracy. Finally, an analysis of seasonal and inter-annual snowmelt patterns highlighted distinct melt differences between lower, middle, and upper elevations. Snowmelt was generally most frequent (70% - 95% of the snow-covered season) at the lower elevations where snow cover

  2. Inter-annual patterns of aggression and pair bonding in captive American flamingos (Phoenicopterus ruber).

    PubMed

    Frumkin, Nathan B; Wey, Tina W; Exnicios, Megan; Benham, Caroline; Hinton, Mitchell G; Lantz, Samantha; Atherton, Carolyn; Forde, Debbie; Karubian, Jordan

    2016-01-01

    Because zoos typically house animals for extended periods of time, longitudinal studies can play an important role in evaluating and optimizing animal care and management. For example, information on patterns of aggression and mating behavior across years can be used to monitor well-being, assess response to changes to group composition, and promote successful reproduction. Here, we report on patterns of aggression and pair bonding by American flamingos (Phoenicopterus ruber) at the Audubon Zoo, New Orleans USA across 4 years (2012-2015), a period that included a simultaneous introduction and removal of individuals in 2014. At the population level, overall rates and social network indices of aggressive interactions were relatively stable over the study period, without a strong signal of the 2014 replacement event. At the individual level, flamingos exhibited a high degree of within-individual consistency in levels of aggression initiated (W = 0.530, P < 0.001), and received (W = 0.369, P = 0.042). In terms of pair bonds, females re-paired with the same individuals across years more frequently (between 58% and 100% from year to year) than they switched mates, and no bonds were established between pre-existing and introduced individuals. These findings indicate a high degree of stability in aggression and pair bonding behavior in this population of captive flamingos, at both the population and individual level. Longitudinal studies such as this one provide an opportunity to better our understanding of flamingos and other long-lived, group-living animals along with their management needs, especially in terms of maintaining social cohesion in captivity and improving captive breeding programs. PMID:26882002

  3. Inter-annual snow accumulation and melt patterns in a sub-alpine mixed conifer forest: results from a distributed physically based snow model

    NASA Astrophysics Data System (ADS)

    Musselman, K. N.; Molotch, N. P.; Margulis, S. A.; Kirchner, P. B.; Bales, R. C.

    2011-12-01

    Seasonally snow covered mid-latitude forests may be highly sensitive to climate change as they often overlap or reside near the present-day synoptic mean rain-snow transition zone. Limited capabilities of satellite remote sensing in forested, steep terrain combined with sparse in-situ observations emphasize the need for improved numerical simulations of the distribution of snow water equivalent in these regions. The land surface / snowmelt model Alpine3D was used to simulate snow accumulation and melt in the 7.22 km2 sub-alpine Wolverton basin in the southern Sierra Nevada, California. The basin is part of the Southern Sierra Nevada Critical Zone Observatory. Results from three snow seasons were evaluated against data from a distributed network of automated snow depth sensors, repeated catchment-wide snow survey measurements conducted in 2008 and 2009, and LiDAR data from 2010. Compared to the local 86-year historical record, the three years of observation accumulated average (2008), 48% below average (2009) and 43% above average (2010) maximum annual SWE. A mid-winter rain-on-snow event occurred in both 2008 and 2009. The inter-annual variability in maximum SWE combined with inter-annual differences in the timing and type of precipitation events, the timing of seasonal melt onset, and differences in the persistence of spring cloud cover caused significant inter-annual variability in areal snow cover depletion rates. In 2009, the year with the least precipitation, the most spring cloud cover, and a basin-wide late-January rain event, SWE patterns exhibited the least spatial variability and areal snow cover depletion was rapid. Conversely, the greatest spatial variability in SWE was simulated in 2010, the year with the most precipitation, no rain events, and a melt season that extended into early summer. The areal snow cover depletion curve for this year exhibited a rapid exponential phase as in 2009, but a distinctly different transitional phase as deep snow cover

  4. Inter-annual temperature and precipitation variations over the Litani Basin in response to atmospheric circulation patterns

    NASA Astrophysics Data System (ADS)

    Ramadan, H. H.; Ramamurthy, A. S.; Beighley, R. E.

    2012-05-01

    This study examines the sensitivity of a mid-size basin's temperature and precipitation response to different global and regional climate circulation patterns. The implication of the North Atlantic Oscillation (NAO), El Niño Southern Oscillation (ENSO), Indian Monsoon and ten other teleconnection patterns of the Northern Hemisphere are investigated. A methodology to generate a basin-scale, long-term monthly surface temperature and precipitation time series has been established using different statistical tests. The Litani River Basin is the focus of this study. It is located in Lebanon, east of the Mediterranean Basin, which is known to have diverse geophysical and environmental characteristics. It was selected to explore the influence of the diverse physical and topographical features on its hydroclimatological response to global and regional climate patterns. We also examine the opportunity of conducting related studies in areas with limited long-term measured climate and/or hydrological data. Litani's monthly precipitation and temperature data have been collected and statistically extrapolated using remotely sensed data products from satellites and as well as in situ gauges. Correlations between 13 different teleconnection indices and the basin's precipitation and temperature series are investigated. The study shows that some of the annual and seasonal temperature and precipitation variance can be partially associated with many atmospheric circulation patterns. This would give the opportunity to relate the natural climate variability with the watershed's hydroclimatology performance and thus differentiate it from other anthropogenic induced climate change outcomes.

  5. Five years of phenological monitoring in a mountain grassland: inter-annual patterns and evaluation of the sampling protocol

    NASA Astrophysics Data System (ADS)

    Filippa, Gianluca; Cremonese, Edoardo; Galvagno, Marta; Migliavacca, Mirco; Morra di Cella, Umberto; Petey, Martina; Siniscalco, Consolata

    2015-12-01

    The increasingly important effect of climate change and extremes on alpine phenology highlights the need to establish accurate monitoring methods to track inter-annual variation (IAV) and long-term trends in plant phenology. We evaluated four different indices of phenological development (two for plant productivity, i.e., green biomass and leaf area index; two for plant greenness, i.e., greenness from visual inspection and from digital images) from a 5-year monitoring of ecosystem phenology, here defined as the seasonal development of the grassland canopy, in a subalpine grassland site (NW Alps). Our aim was to establish an effective observation strategy that enables the detection of shifts in grassland phenology in response to climate trends and meteorological extremes. The seasonal development of the vegetation at this site appears strongly controlled by snowmelt mostly in its first stages and to a lesser extent in the overall development trajectory. All indices were able to detect an anomalous beginning of the growing season in 2011 due to an exceptionally early snowmelt, whereas only some of them revealed a later beginning of the growing season in 2013 due to a late snowmelt. A method is developed to derive the number of samples that maximise the trade-off between sampling effort and accuracy in IAV detection in the context of long-term phenology monitoring programmes. Results show that spring phenology requires a smaller number of samples than autumn phenology to track a given target of IAV. Additionally, productivity indices (leaf area index and green biomass) have a higher sampling requirement than greenness derived from visual estimation and from the analysis of digital images. Of the latter two, the analysis of digital images stands out as the more effective, rapid and objective method to detect IAV in vegetation development.

  6. North Atlantic atmospheric and ocean inter-annual variability over the past fifty years - Dominant patterns and decadal shifts

    NASA Astrophysics Data System (ADS)

    Hauser, Tristan; Demirov, Entcho; Zhu, Jieshun; Yashayaev, Igor

    2015-03-01

    The atmosphere and ocean of the North Atlantic have undergone significant changes in the past century. To understand these changes, their mechanisms, and their regional implications requires a quantitative understanding of processes in the coupled ocean and atmosphere system. Central to this understanding is the role played by the dominant patterns of ocean and atmospheric variability which define coherent variations in physical characteristics over large areas. Cluster analysis is used in this article to identify the patterns of the North Atlantic atmospheric variability in the subseasonal and interannual spectral intervals. Four dominant subseasonal weather regimes are defined using Bayesian Gaussian mixture models. All correlation patterns of the Sea Level Pressure (SLP) anomalies with the membership probability time series for the weather regimes show similarities with the dipole structure typical for the North Atlantic Oscillation (NAO). The SLP patterns of two of the regimes represent the opposite phases NAO+ and NAO-. The two other weather regimes, the Atlantic Ridge (AR) and Scandinavian-Greenland dipole (SG), have dipole spatial structures with the northern and southern centers of action shifted with respect to the NAO pattern. These two patterns define blocking structures over Scandinavia and near the southern tip of Greenland, respectively. The storm tracks typical for the four regimes resemble the well known paths for positive/negative phases of NAO for the NAO+/NAO- weather regimes, and paths influenced by blocking off the south Greenland tip for AR and over Scandinavia for SG. The correlation patterns of momentum and heat fluxes to the ocean for the four regimes have tripole structures with positive (warm) downward heat flux anomalies over the Subpolar North Atlantic (SPNA) for the NAO- and the AR and negative heat flux anomalies over the SPNA for the NAO+. The downward heat flux anomalies associated with the SG are negative over the Labrador Sea and

  7. From egg production to recruits: Connectivity and inter-annual variability in the recruitment patterns of European anchovy in the northwestern Mediterranean

    NASA Astrophysics Data System (ADS)

    Ospina-Alvarez, Andres; Catalán, Ignacio A.; Bernal, Miguel; Roos, David; Palomera, Isabel

    2015-11-01

    We show the application of a Spatially-Explicit Individual-Based Model (SEIBM) to understand the recruitment process of European anchovy. The SEIBM is applied to simulate the effects of inter-annual variability in parental population spawning behavior and intensity, and ocean dynamics, on the dispersal of eggs and larvae from the spawning area in the Gulf of Lions (GoL) towards the coastal nursery areas in the GoL and Catalan Sea (northwestern Mediterranean Sea). For each of seven years (2003-2009), we initialize the SEIBM with the real positions of anchovy eggs during the spawning peak, from an acoustics-derived eggs production model. We analyze the effect of spawners' distribution, timing of spawning, and oceanographic conditions on the connectivity patterns, growth, dispersal distance and late-larval recruitment (14 mm larva recruits, R14) patterns. The area of influence of the Rhône river plume was identified as having a high probability of larval recruitment success (64%), but up to 36% of R14 larvae end up in the Catalan Coast. We demonstrate that the spatial paths of larvae differ dramatically from year to year, and suggest potential offshore nursery grounds. We showed that our simulations are coherent with existing recruitment proxies and therefore open new possibilities for fisheries management.

  8. Inter-American Foundation Annual Report 1987.

    ERIC Educational Resources Information Center

    Inter-American Foundation, Rosslyn, VA.

    This annual report from the Inter-American Foundation (IAF), a federal development agency, includes letters from foundation officials describing the IAF-funded work in poverty areas of Latin America and the Caribbean. The report describes IAF's In-Country Support System (ICS), staffed by local professionals who assist grantees and report their…

  9. Inter-American Foundation Annual Report 1988.

    ERIC Educational Resources Information Center

    Inter-American Foundation, Rosslyn, VA.

    The Inter-American Foundation (IAF), an independent agency created by Congress, funds local private organizations that support the self-help efforts of the poor in Latin America and the Caribbean. In fiscal year 1988, IAF approved 208 new grants, 173 grant supplements, and other program activities totaling nearly $25 million. The average grant…

  10. Inter-annual and inter-individual variations in survival exhibit strong seasonality in a hibernating rodent.

    PubMed

    Le Cœur, Christie; Chantepie, Stéphane; Pisanu, Benoît; Chapuis, Jean-Louis; Robert, Alexandre

    2016-07-01

    Most research on the demography of wild animal populations has focused on characterizing the variation in the mortality of organisms as a function of intrinsic and environmental characteristics. However, such variation in mortality is difficult to relate to functional life history components (e.g. reproduction, dispersal, hibernation) due to the difficulty in monitoring biological processes at a sufficiently fine timescale. In this study, we used a 10-year individual-based data set with an infra-annual timescale to investigate both intra- and inter-annual survival patterns according to intrinsic and environmental covariates in an introduced population of a small hibernating rodent, the Siberian chipmunk. We compared three distinct periods related to particular life history events: spring reproduction, summer reproduction and hibernation. Our results revealed strong interactions between intrinsic and temporal effects. First, survival of male chipmunks strongly decreases during the reproduction periods, while survival is high and equal between sexes during hibernation. Second, the season of birth affects the survival of juveniles during their first hibernation, which does not have long-lasting consequences at the adult stage. Third, at an inter-annual scale, we found that high food resource availability before hibernation and low chipmunk densities specifically favour subsequent winter survival. Overall, our results confirm that the well-known patterns of yearly and inter-individual variation of mortality observed in animals are themselves strongly variable within a given year, suggesting that they are associated with various functional components of the animals' life history. PMID:26969470

  11. Trends of satellite derived chlorophyll-a (1997-2011) in the Bohai and Yellow Seas, China: Effects of bathymetry on seasonal and inter-annual patterns

    NASA Astrophysics Data System (ADS)

    Liu, Dongyan; Wang, Yueqi

    2013-09-01

    The spatial and temporal variability of sea surface chlorophyll-a (Chl-a) concentrations in the Bohai and Yellow Seas were analyzed, using satellite-derived Chl-a products from SeaWiFS and MODIS sensors over the period of September 1997-September 2011. A set of monthly and cloud-free Chl-a data was produced by the Data Interpolating Empirical Orthogonal Function (DINEOF) method. The results indicate that there are different Chl-a seasonal patterns existing in the Yangtze River mouth, coastal and offshore waters, respectively. In the Yangtze River mouth, a long-lasting Chl-a peak (May-September) is seen in summer. In coastal waters, two significant Chl-a maxima occur in winter-spring and late summer, respectively. In offshore waters, only one significant spring (March-April) Chl-a maximum is evident with a time lag of 1-3 months to coastal waters and the signal of autumn maximum is very weak. In coastal waters, wind-tide-thermohaline circulations and East Asia summer rainy monsoon may important physical factors to impact the seasonal pattern of Chl-a, but increased human activity (e.g., eutrophication, dam) could significantly enhance this process. In offshore waters, the impact on the circulation of the YSWC in winter and YSCW in summer in the central Yellow Sea could be important physical factor in explaining the variability of Chl-a in seasonal patterns. The decadal trends of Chl-a and sea surface temperature are decreasing in coastal waters, with a significantly positive correlation. In offshore waters, the decadal trends of Chl-a is increasing but a slight decreasing sea surface temperature trend is seen, and they indicate a negative correlation. The highest Chl-a values (3.0-5.0 mg m-3) and the lowest variability (STD < 0.3 mg m-3) are observed in coastal waters, in the adjacent sea area of the Yangtze River and Yellow River mouths where the water depth is less than 20 m. Compared with coastal waters and the sea adjacent to the large river mouths, the central

  12. Estimating inter-annual runoff variability from global hydroclimatic data

    NASA Astrophysics Data System (ADS)

    Peel, Murray; McMahon, Thomas; Finlayson, Brian

    2016-04-01

    Inter-annual variability of runoff, measured by the coefficient of variation of annual runoff (RCv), is an important constraint on reservoir yield and storage size for water resources management. For a catchment with a fixed storage capacity, any increase in reservoir inflow RCv translates into reduced reservoir yield for a given reliability of supply. Developing an improved understanding of the physical influences on inter-annual runoff variability around the world and how these may change in future is of vital importance to achieving on-going robust water and catchment management. Here we take a large-scale Comparative Hydrology approach to develop empirical relationships for RCv using a global hydroclimatic data set of 588 catchments. Empirical RCv relationships are developed for the World and catchments experiencing predominantly (≥75% catchment area) tropical, arid, temperate or cold climate types. The RCv relationships are developed specifically using non-streamflow based predictor variables so they can be used for predicting RCv in ungauged basins (the PUB problem - Prediction in Ungauged Basins) and or ungauged climates (the PUC problem - Prediction in Ungauged Climates) if past or future projections of the required predictor variables are available. Empirical relationship predictor variables are based on precipitation, evaporative demand, vegetation and topography. Key variables that contribute to explaining RCv in each relationship will be assessed to identify the dominant drivers of RCv and how the contribution of those drivers varies between regions and climate types, with particular focus on inter-annual climate variability.

  13. Tropical inter-annual SST oscillations and Southern Ocean swells

    NASA Astrophysics Data System (ADS)

    Fan, Yalin; Rogers, Erick; Jensen, Tommy

    2016-04-01

    The possibility of teleconnections between Southern Ocean swells and sea surface temperature (SST) anomalies on inter-annual time scales in the Eastern Pacific Niño3 region and southeastern Indian Ocean is investigated using numerical wave models. Two alternative parameterizations for swell dissipation are used. It is found that swell dissipation in the models is not directly correlated with large inter-annual variations such as the El Nino - Southern Oscillation (ENSO) or Indian Ocean Dipole (IOD). However, using one of the two swell dissipation parameterizations, a correlation is found between observed SST anomalies and the modification of turbulent kinetic energy flux (TKEF) by Southern Ocean swells due to the damping of short wind waves: modeled reduction of TKEF is in opposite phase with the SST anomalies in the Niño-3 region, indicating a potential positive feedback. The modeled bi-monthly averaged TKEF reduction in the southeastern Indian Ocean is also well correlated with the IOD mode.

  14. On the use of a water balance to evaluate inter-annual terrestrial ET variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurately measuring inter-annual variability in terrestrial evapotranspiration (ET) is a major challenge for efforts to detect inter-annual variability in the hydrologic cycle. Based on comparisons with annual ET values derived from a terrestrial water balance analysis, past research has cast doubt...

  15. Inter-annual variability of North Sea plaice spawning habitat

    NASA Astrophysics Data System (ADS)

    Loots, C.; Vaz, S.; Koubbi, P.; Planque, B.; Coppin, F.; Verin, Y.

    2010-11-01

    Potential spawning habitat is defined as the area where environmental conditions are suitable for spawning to occur. Spawning adult data from the first quarter (January-March) of the International Bottom Trawl Survey have been used to study the inter-annual variability of the potential spawning habitat of North Sea plaice from 1980 to 2007. Generalised additive models (GAM) were used to create a model that related five environmental variables (depth, bottom temperature and salinity, seabed stress and sediment type) to presence-absence and abundance of spawning adults. Then, the habitat model was applied each year from 1970 to 2007 to predict inter-annual variability of the potential spawning habitat. Predicted responses obtained by GAM for each year were mapped using kriging. A hierarchical classification associated with a correspondence analysis was performed to cluster spawning suitable areas and to determine how they evolved across years. The potential spawning habitat was consistent with historical spawning ground locations described in the literature from eggs surveys. It was also found that the potential spawning habitat varied across years. Suitable areas were located in the southern part of the North Sea and along the eastern coast of England and Scotland in the eighties; they expanded further north from the nineties. Annual survey distributions did not show such northward expansion and remained located in the southern North Sea. This suggests that this species' actual spatial distribution remains stable against changing environmental conditions, and that the potential spawning habitat is not fully occupied. Changes in environmental conditions appear to remain within plaice environmental ranges, meaning that other factors may control the spatial distribution of plaice spawning habitat.

  16. Detecting Inter-Cusp and Inter-Tooth Wear Patterns in Rhinocerotids

    PubMed Central

    Taylor, Lucy A.; Kaiser, Thomas M.; Schwitzer, Christoph; Müller, Dennis W. H.; Codron, Daryl; Clauss, Marcus; Schulz, Ellen

    2013-01-01

    Extant rhinos are the largest extant herbivores exhibiting dietary specialisations for both browse and grass. However, the adaptive value of the wear-induced tooth morphology in rhinos has not been widely studied, and data on individual cusp and tooth positions have rarely been published. We evaluated upper cheek dentition of browsing Diceros bicornis and Rhinoceros sondaicus, mixed-feeding R. unicornis and grazing Ceratotherium simum using an extended mesowear method adapted for rhinos. We included single cusp scoring (EM(R)-S) to investigate inter-cusp and inter-tooth wear patterns. In accordance with previous reports, general mesowear patterns in D. bicornis and R. sondaicus were attrition-dominated and C. simum abrasion-dominated, reflecting their respective diets. Mesowear patterns for R. unicornis were more attrition-dominated than anticipated by the grass-dominated diet, which may indicate a low intake of environmental abrasives. EM(R)-S increased differentiation power compared to classical mesowear, with significant inter-cusp and inter-tooth differences detected. In D. bicornis, the anterior cusp was consistently more abrasion-dominated than the posterior. Wear differences in cusp position may relate to morphological adaptations to dietary regimes. Heterogeneous occlusal surfaces may facilitate the comminution of heterogeneous browse, whereas uniform, broad grinding surfaces may enhance the comminution of physically more homogeneous grass. A negative tooth wear gradient was found in D. bicornis, R. sondaicus and R. unicornis, with wear patterns becoming less abrasion-dominated from premolars to molars. No such gradients were evident in C. simum which displayed a uniform wear pattern. In browsers, premolars may be exposed to higher relative grit loads, which may result in the development of wear gradients. The second premolar may also have a role in food cropping. In grazers, high absolute amounts of ingested abrasives may override other signals, leading to

  17. Inter-annual variations in the SeaWiFS global chlorophyll a concentration (1997-2007)

    NASA Astrophysics Data System (ADS)

    Vantrepotte, V.; Mélin, F.

    2011-04-01

    The SeaWiFS data set covering the period 1997-2007 is used to develop a framework for a comprehensive description of the inter-annual variations in chlorophyll a concentration (Chl a). For each grid cell, the monthly Chl a series is decomposed into seasonal, irregular and trend-cycle terms with the Census X-11 technique that is an iterative band-pass filter algorithm. This approach allows variations in the annual cycle, while the trend-term isolates the multi-annual evolution in the mean level of the signal. The patterns with relatively large inter-annual variations are selected using the variance due to the trend-term with respect to the total variance, and are compared with maps of monotonic trends derived by a non-parametric Kendall analysis. Most of these patterns are identified in the subtropical domain (30°S-30°N), even though there are patterns with strong variations at mid-latitudes, particularly in the Northeast Atlantic and South of Australia. The time series found within each pattern of interest are found coherent. Conversely, the ensemble of spatially averaged time series of Chl a trend-terms shows a diversity of evolutions, with rather monotonic changes for all or part of the period, abrupt shifts or low-frequency oscillations, sometimes coupled with a modification in the amplitude of the annual cycle. Some of these series are correlated with climate indices, and those in subtropical regions usually show a negative correlation with the equivalent trend-term calculated for sea surface temperature. The identified inter-annual signals should be further monitored with longer time series and can serve as test cases for biogeochemical models.

  18. Inter-annual variability in Alaskan net ecosystem CO2 exchange

    NASA Astrophysics Data System (ADS)

    Luus, Kristina; Lindaas, Jakob; Commane, Roisin; Euskirchen, Eugenie; Oechel, Walter; Zona, Donatella; Chang, Rachel; Kelly, Richard; Miller, Charles; Wofsy, Steven; Lin, John

    2015-04-01

    The high-latitude biospheric carbon cycle's responses to climate change are predicted to have an important role in determining future atmospheric concentrations of CO2. In response to warming soil and air temperatures, Arctic wetlands have been observed to increase rates of both soil C efflux and vegetation C uptake through photosynthesis. However, insights into the regional-scale consequences of these processes for net C uptake have been limited by the large uncertainties existing in process-based model estimates of Arctic net ecosystem CO2 exchange (NEE). The Polar Vegetation Photosynthesis and Respiration Model (PolarVPRM) instead provides data-driven, satellite-based estimates of high-latitude NEE, using a framework which specifically accounts for polar influences on NEE. PolarVPRM calculates NEE as the sum of respiration (R) and gross ecosystem exchange (GEE), where GEE refers to the light-dependent portion of NEE: NEE= -GEE + R. Meteorological inputs for PolarVPRM are provided by the North American Regional Reanalysis (NARR), and land surface inputs are acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS). Growing season R is calculated from air temperature, and subnivean R is calculated according to soil temperature. GEE is calculated according to shortwave radiation, air temperature, and MODIS-derived estimates of soil moisture and vegetation biomass. Previously, model validation has indicated that PolarVPRM showed reasonably good agreement with eddy covariance observations at nine North American Arctic sites, of which three were used for calibration purposes. For this project, PolarVPRM NEE was calculated year-round across Alaska at a three-hourly temporal resolution and a spatial resolution of 1 6°×1 4° (latitude × longitude). The objective of this work was to gain insight into inter-annual variability in Alaskan NEE, R and GEE, and an understanding of which meteorological and land surface drivers account for these observed patterns

  19. Inter-annual sea level variability in the southern South China Sea

    NASA Astrophysics Data System (ADS)

    Soumya, M.; Vethamony, P.; Tkalich, P.

    2015-10-01

    The South China Sea (SCS) is the largest marginal sea in the western Pacific Basin. Sea level anomalies (SLAs) in the southern South China Sea (SSCS) are assumed to be governed by various phenomena associated with the adjacent parts of the Indian Ocean and the Pacific Ocean. We have used monthly sea level anomalies obtained from 12 tide gauge stations of PSMSL and UHSLC and merged and gridded AVISO products of SLAs (sea level anomalies) derived from satellite altimeter. We find that IOD-influenced inter-annual variations are found only in the southwestern and southeastern coastal regions of SSCS. Our analysis reveals that inter-annual regional sea level drops are associated with positive phase of the IOD, and the rises with negative phase of the IOD. SLA variations at decadal scale in the southeastern and northern Gulf of Thailand correlate with Pacific Decadal Oscillations (PDO). Multiple linear regression analysis of inter-annual SLAs and climate indices shows that IOD induced inter-annual variations dominate in the southwestern SCS and it contributes to about ~ 40% of inter-annual sea level variation. Meanwhile, ENSO contributes to around ~ 30% variation in sea level in the southwestern and ~ 40% variation in the southeastern SSCS. The present study also suggests that inter-annual SLA variations in the SSCS can occur by ENSO and IOD induced changes in wind stress curl and volume transport variations.

  20. Inter-Annual Variability of Aerosol Optical Depth over East Asia during 2000-2011 summers

    NASA Astrophysics Data System (ADS)

    Liu, J.; Liu, Y.; Tao, S.

    2013-12-01

    Aerosols degrade air quality, perturb atmospheric radiation, and impact regional and global climate. Due to a rapid increase of anthropogenic emissions, aerosol loading over East Asia (EA) is markedly higher than other industrialized regions, motivating a need to characterize the evolution of aerosols and understand the associated drivers. Based on the MISR satellite data during 2000-2011, a wave-like inter-annual variation of summertime aerosol optical depth (SAOD) is observed over the highly populated North China Plain (NCP) in East Asia. Specifically, the peak to trough ratio of SAOD ranges from 1.4 to 1.6, with a period of 3-4y. This variation pattern differs apparently from what has been seen in EA emissions, indicating a periodic change in regional climate pattern during the past decade. Investigations on meteorological fields over the region reveal that the high SAOD is generally associated with enhanced Philippine Sea Anticyclone Anomaly (PSAA), which weakens southeasterlies over northeastern EA and depresses air ventilation. Alternatively, a higher temperature or lower relative humidity is found to be coincident with reduced SAOD. The behavior of PSAA has been found previously to be modulated by the El Niño southern oscillations (ENSO), which thereby could disturb the EA SAOD as well. Rather than changing coherently with the ENSO activity, SAOD peaks over the NCP are found to be accompanied by the rapid transition of El Niño warm to cold phases developed four months ahead. An index measuring the ENSO development during January-April is able to capture the inter-annual variability of NCP SAOD during 2000-2011. This indicates a need to integrate the consideration of large-scale periodic climate variability in the design of regional air quality policy.

  1. A view of annual water quality cycle and inter-annual variations in agricultural headwater catchment (Kervidy-Naizin, France)

    NASA Astrophysics Data System (ADS)

    Aubert, A.; Gascuel-odoux, C.; Merot, P.; Grimaldi, C.; Gruau, G.; Ruiz, L.

    2011-12-01

    Climatic conditions impact biotransformation and transfer of solutes. Therefore, they modify solute emissions in streams. Studying these modifications requires long term and detailed monitoring of both internal processes and river loads, which are rarely combined. The Kervidy-Naizin catchment, implemented in 1993, is part of the French network of catchment for environmental research (SOERE RBV, focused on the Critical Zone). It is an intensive agricultural catchment located in a temperate climate in Western France (Brittany) (Molenat et al., 2008; Morel et al., 2009). It presents shallow aquifers due to impervious bedrock. Both hydrology and water chemistry are monitored with a daily time step since 2000-01, as well as possible explanatory data (land use, meteorology, etc.). Concentrations in major anions in this catchment are extremely high, which make people call it a "saturated" catchment. We identified annual patterns for chloride, sulphate, dissolved organic and inorganic carbon and nitrate concentration variations. First, we considered the complete set of concentration data as function of the time. From that, we foresaw 3 cyclic temporal patterns. Then, from representing the concentrations as function of meteorological parameters, intra-annual hysteretic variations and their inter-annual variations were clearly identified. Our driving question is to know if and how climatic conditions are responsible for variations of the patterns in and between years. In winter, i.e. rainy and cold period, rainfall is closely linked to discharge because of a direct recharge to the shallow groundwater. Reversely, in transition periods (spring and fall) and hot periods, both rainfall and temperature influences discharge in relation to their range of variations. Moreover, biological processes, driven by temperature and wetness, also act during these periods. On the whole, we can emphasize the specificity of water chemistry patterns for each element. Noticeable differences

  2. Watershed-scale response of groundwater recharge to inter-annual and inter-decadal variability in precipitation (Alberta, Canada)

    NASA Astrophysics Data System (ADS)

    Hayashi, Masaki; Farrow, Christopher R.

    2014-12-01

    Groundwater recharge sets a constraint on aquifer water balance in the context of water management. Historical data on groundwater and other relevant hydrological processes can be used to understand the effects of climatic variability on recharge, but such data sets are rare. The climate of the Canadian prairies is characterized by large inter-annual and inter-decadal variability in precipitation, which provides opportunities to examine the response of groundwater recharge to changes in meteorological conditions. A decadal study was conducted in a small (250 km2) prairie watershed in Alberta, Canada. Relative magnitude of annual recharge, indicated by water-level rise, was significantly correlated with a combination of growing-season precipitation and snowmelt runoff, which drives depression-focussed infiltration of meltwater. Annual precipitation was greater than vapour flux at an experimental site in some years and smaller in other years. On average precipitation minus vapour flux was 10 mm y-1, which was comparable to the magnitude of watershed-scale groundwater recharge estimated from creek baseflow. Average baseflow showed a distinct shift from a low value (4 mm y-1) in 1982-1995 to a high value (15 mm y-1) in 2003-2013, indicating the sensitivity of groundwater recharge to a decadal-scale variability of meteorological conditions.

  3. Glycosylation pattern of human inter-alpha-inhibitor heavy chains.

    PubMed Central

    Flahaut, C; Capon, C; Balduyck, M; Ricart, G; Sautiere, P; Mizon, J

    1998-01-01

    Human inter-alpha-inhibitor (IalphaI) is a plasma serine-proteinase inhibitor. It consists of three polypeptide chains covalently linked by a glycosaminoglycan chain: a light chain named bikunin carrying the anti-proteinase activity and two heavy chains, H1 and H2, which exhibit specific properties, e.g. they interact with hyaluronan thus stabilizing the extracellular matrix. In this study, using matrix-assisted laser desorption ionization-time-of-flight MS and amino acid sequencing of tryptic peptides, we provide a detailed analysis of the glycosylation pattern of both heavy chains. H1 carries two complex-type N-glycans of predominantly biantennary structure linked to asparagine residues at positions 256 and 559 respectively. In contrast, the oligosaccharides attached to H2 are a complex-type N-glycan in the N-terminal region of the protein (Asn64) and three to four type-1 core-structure O-glycans mono- or di-sialylated, clustered in the C-terminal region. We propose that these O-glycans might function as a recognition signal for the H2 heavy chain. The biological implications of this hypothesis, notably for the biosynthetic pathway of IalphaI, are discussed. PMID:9677337

  4. Inter-annual variability influences the eco-evolutionary dynamics of range-shifting

    PubMed Central

    Bocedi, Greta; Dytham, Calvin; Travis, Justin M.J.

    2014-01-01

    Understanding the eco-evolutionary dynamics of species under rapid climate change is vital for both accurate forecasting of biodiversity responses and for developing effective management strategies. Using an individual-based model we demonstrate that the presence and form (colour) of inter-annual variability in environmental conditions can impact the evolution of dispersal during range shifts. Under stable climate, temporal variability typically results in higher dispersal. However, at expanding margins, inter-annual variability actually inhibits the evolution of higher emigration propensities by disrupting the spatial sorting and natural selection processes. These results emphasize the need for future theoretical studies, as well as predictive modelling, to account for the potential impacts of inter-annual variability. PMID:24498572

  5. Inter- and intra-annual patterns of Ulva prolifera green tides in the Yellow Sea during 2007-2009, their origin and relationship to the expansion of coastal seaweed aquaculture in China.

    PubMed

    Keesing, John K; Liu, Dongyan; Fearns, Peter; Garcia, Rodrigo

    2011-06-01

    The large green-tide events that occurred in the Yellow Sea in 2008 (3489km(2)) and 2009 (4994km(2)) are shown to be novel events preceded only once by a much smaller event in 2007 (82km(2)). The blooms originated in the coastal area of Jiangsu province and spread north-east towards the Shandong Peninsula. The blooms grew at different rates and mesoscale variability in surface winds explained the differences in the spatial and temporal patterns of blooms in 2008 and 2009. The 2009 bloom was tracked to its origin immediately offshore of extensive intertidal flats between Yancheng and Nantong where recent rapid expansion of Porphyra aquaculture has occurred. We review published hypotheses which have been advanced to explain the occurrence of blooms and in light of our findings, we conclude that the accumulation and disposal of waste Ulva prolifera from Porphyra aquaculture rafts is the most likely cause of the blooms. PMID:21497856

  6. Inter-annual variation in NO2 over the United States

    NASA Astrophysics Data System (ADS)

    Chand, D.; McClure, S.; Schichtel, B. A.; Huddleston, J.; Malm, W. C.; Moore, T.

    2009-12-01

    Nitrogen dioxide (NO2) plays a key part in atmospheric photochemical processes, including catalytic production of ozone. Emissions of nitrogen oxides also result in nitric acid deposition and increase radiative forcing effects due to the absorption of downward propagating visible light. Recent studies based on GOME and SCIAMACHY satellites observations have shown that NO2 concentrations over the United States have been decreasing by 1-2% per year [Richter et al., 2005; Ghude et al., 2009]. To overcome the detection and sensitivity limitations of these satellites, an improved satellite (Ozone Monitoring Instrument - OMI) was launched in 2004 on the Aura platform as a part of the A-train constellation of satellites. In this study we are using four years (2005-08) of OMI observations to study short-term trends by assessing the spatial and temporal patterns of variation in NO2 over the United States. The focus of this study is over the subdomain 30N-50N, 70W-125W. Our initial analysis suggests that NO2 over the eastern as well as western United States continues to decrease from 2005 through 2008; however, the rate of decrease is higher over the eastern United States. This analysis of Inter-annual variation in NO2 using OMI observations will be used to compare the existing results from GOME and SCIAMACHY satellites. Detail results will be presented in the AGU meeting. References: Richter et al., Increase in tropospheric nitrogen dioxide over China observed from space, Nature, volume 437, doi:10.1038/nature04092, 2005. Ghude et al., Satellite derived trends in NO2 over the major global hotspot regions during the past decade and their inter-comparison, Environmental Pollution, volume 157 Page 1873-1878, 2009.

  7. Inter-annual variation in the foraging ecology of a brown bear population in southwest Alaska

    NASA Astrophysics Data System (ADS)

    Stricker, C. A.; Kovach, S. D.; Collins, G. H.; Farley, S. D.; Rye, R. O.; Hinkes, M. T.

    2010-12-01

    Brown bear (Ursus arctos) population size correlates with density of high-quality food resources. We report on a ten-year study (1993 - 2003) of brown bear nutritional ecology in southwestern Alaska during which changes in resource availability and density occurred. The diets of 21 female bears captured multiple years were characterized by stable isotope analysis (δ13C, δ15N, and δ34S) of guard hairs and putative diet items, followed by application of a Bayesian mixing model to derive assimilated diet estimates. Diet estimates were subsequently used to characterize individual-level resource specialization. Over the entire study period, salmon accounted for the highest proportion of bear diets (42.1%), followed by berries (24.5%), mammals (13.5%), freshwater fish (11.2%), and other plant matter (8.7%). The average salmon contribution to bear diets declined significantly from 48% to 34% following a precipitous reduction in salmon escapement mid-way through the study, after which the bear population shifted toward a more generalist diet. However, evaluation of individual animals recaptured multiple times during the study revealed variation in inter-annual dietary habits unrelated to the salmon crash. Individual variation presumably reflects local density changes in a variety of resources, with concomitant annual shifts in the degree of individual specialization. We also relate these patterns to other individual traits, such as reproductive status, home range, and habitat use to better constrain foraging habits. This study provides unique insights into the nutritional ecology of Alaskan brown bears and complements traditional wildlife studies by offering important covariates to better understand changes in population vital rates.

  8. The impact of inter-annual variability in hydrodynamic conditions on plaice settlement success

    NASA Astrophysics Data System (ADS)

    Tiessen, Meinard; Gerkema, Theo; Ruardij, Piet; van der Veer, Henk

    2014-05-01

    Using a hydrodynamic model coupled to a particle tracking routine, the impact of variability in hydrodynamic conditions on drifting plaice eggs and larvae and their successful settlement in nursery areas was studied. The life cycle of many marine fish species consists of various life stages: Spawning at open sea, pelagic egg and larval stages and often a juvenile stage bound to shallow water nursery grounds. Numerous studies have demonstrated that pelagic stages appear to be the most critical in determining ultimate year-class success, which holds true, for example, for European plaice (Pleuronectes platessa). Plaice spawning grounds in the middle of the North Sea and in the English Channel are connected to juvenile nursery areas (such as the Wadden Sea) via (semi-)passive drift governed by residual currents. Field data from especially the Balgzand nursery area have shown a strong variability in the number of plaice juveniles settling there over the years. Changes to current patterns and water temperatures are expected to strongly contribute to this inter-annual variability in settlement success. Here, we investigate these effects on pelagic plaice drift and settlement using a coupled numerical model: A 3D hydrodynamic model (GETM) was used to produce hydrodynamic data at a high spatial and temporal resolution, for the years 1994 - 2005. This data was subsequently fed into a particle tracking routine (GITM), that computed the trajectories for a million particles (representing pelagic plaice) for each year. In order to focus on the physical processes, several biological contributions such as behaviour (vertical migration) and mortality were excluded from the simulations. Spawning periods and locations, drift durations, and settlement requirements were selected around known plaice characteristics. Results showed a strong inter-annual variability in the drift direction, drift duration and settlement success of the particles, as well as in the absolute number of

  9. Inter-annual, seasonal and spatial variability in nutrient limitation of phytoplankton production in a river impoundment

    USGS Publications Warehouse

    Bukaveckas, P.A.; Crain, A.S.

    2002-01-01

    We characterize seasonal and spatial patterns in phytoplankton abundance, production and nutrient limitation in a mesotrophic river impoundment located in the southeastern United States to assess variation arising from inter-annual differences in watershed inputs. Short-term (48 h) in situ nutrient addition experiments were conducted between May and October at three sites located along the longitudinal axis of the lake. Nutrient limitation was detected in 12 of the 18 experiments conducted over 2 years. Phytoplankton responded to additions of phosphorus alone although highest chlorophyll concentrations were observed in enclosures receiving combined (P and N) additions. Growth responses were greatest at downstream sites and in late summer suggesting that those populations experience more severe nutrient limitation. Interannual variation in nutrient limitation and primary production corresponded to differences in the timing of hydrologic inputs. Above average rainfall and discharge in late-summer (July-October) of 1996 coincided with higher in-lake nutrient concentrations, increased production, and minimal nutrient limitation. During the same period in 1995, discharge was lower, nutrient concentrations were lower, and nutrient limitation of phytoplankton production was more pronounced. Our results suggest that nutrient limitation is common in this river impoundment but that modest inter-annual variability in the timing of hydrologic inputs can substantially influence seasonal and spatial patterns.

  10. Inter-annual Variation in Growing Season Length of a Tropical Seasonal Forest in Northern Thailand

    NASA Astrophysics Data System (ADS)

    Yoshifuji, N.; Tanaka, N.; Suzuki, M.; Tantasirin, C.

    2007-12-01

    Growing season length is an important factor affecting energy balance and water and carbon cycling at deciduous forests. The impact of its inter-annual variation on annual energy and carbon exchange is likely to be critical especially in tropical region because of high radiant energy throughout the year; however, few studies investigated inter-annual variation in growing season length of tropical deciduous forests. This study revealed year-to-year variations in the canopy duration and transpiration period as measures of growing season length using time series data of radiative transmittance and heat pulse velocities of canopy trees in a teak plantation in northern Thailand from 2001 to 2006. This study also examined whether year-to-year variation in growing season revealed by field measurements could be detected by satellite NDVI data, as a first step to investigate the inter- annual variation in growing season length of deciduous forests over tropical monsoon region. Leaf-out and transpiration commenced earlier in 2001 than other years following exceptionally heavy rainfall in the late dry season, suggesting that enhanced soil moisture advanced leaf unfolding and start of transpiration. Leaf-fall and decline in transpiration at the beginning of 2003 were late in coming in correlation with a prolonged rainy season. Declines in transpiration were directly controlled by soil moisture at the beginning of the dry season. These results revealed that soil moisture is a major cause of large inter-annual variation in the growing season at this site. Seasonal variation in NDVI corresponded to that of LAI, while transpiration declined earlier than LAI and NDVI in the dry season. Year-to-year variation in canopy duration could be also detected by NDVI. The variation in canopy duration and transpiration period of this site from 2001-2006 spanned about 60 days. This was much larger than the inter-annual variations previously reported in temperate deciduous forests, implying a

  11. Measurement of inter- and intra-annual variability of landscape fire activity at a continental scale: the Australian case

    NASA Astrophysics Data System (ADS)

    Williamson, Grant J.; Prior, Lynda D.; Jolly, W. Matt; Cochrane, Mark A.; Murphy, Brett P.; Bowman, David M. J. S.

    2016-03-01

    Climate dynamics at diurnal, seasonal and inter-annual scales shape global fire activity, although difficulties of assembling reliable fire and meteorological data with sufficient spatio-temporal resolution have frustrated quantification of this variability. Using Australia as a case study, we combine data from 4760 meteorological stations with 12 years of satellite-derived active fire detections to determine day and night time fire activity, fire season start and end dates, and inter-annual variability, across 61 objectively defined climate regions in three climate zones (monsoon tropics, arid and temperate). We show that geographic patterns of landscape burning (onset and duration) are related to fire weather, resulting in a latitudinal gradient from the monsoon tropics in winter, through the arid zone in all seasons except winter, and then to the temperate zone in summer and autumn. Peak fire activity precedes maximum lightning activity by several months in all regions, signalling the importance of human ignitions in shaping fire seasons. We determined median daily McArthur forest fire danger index (FFDI50) for days and nights when fires were detected: FFDI50 varied substantially between climate zones, reflecting effects of fire management in the temperate zone, fuel limitation in the arid zone and abundance of flammable grasses in the monsoon tropical zone. We found correlations between the proportion of days when FFDI exceeds FFDI50 and the Southern Oscillation index across the arid zone during spring and summer, and Indian Ocean dipole mode index across south-eastern Australia during summer. Our study demonstrates that Australia has a long fire weather season with high inter-annual variability relative to all other continents, making it difficult to detect long term trends. It also provides a way of establishing robust baselines to track changes to fire seasons, and supports a previous conceptual model highlighting multi-temporal scale effects of climate in

  12. Atmospheric modes influence on the inter- annual variability of the Iberian Poleward Current from 1985 to 2006

    NASA Astrophysics Data System (ADS)

    Decastro, M.; Gómez-Gesteira, M.; Álvarez, I.; Crespo, A. J. C.; Ramos, A. M.

    2009-04-01

    The inter-annual variability of the Iberian poleward current (IPC) along the northwestern coast of the Iberian Peninsula (IP) (40- 43N) and its intrusion in the Cantabrian Sea (Navidad, 6- 8W) were analyzed. The January Sea Surface Temperature (J SST) was obtained from the advanced very high resolution radiometer (AVHRR) NOAA satellite from 1985 to 2006. In addition, the dependence of IPC SST on the most representative regional patterns with some influence upon the eastern North Atlantic region was analyzed by means of correlations between November- December atmospheric modes and J SST. The considered modes were: North Atlantic Oscillation pattern (NAO), Eastern Atlantic pattern (EA), Eastern Atlantic Western Russia pattern (EA/WR), Polar/Eurasia pattern (POL) and Scandinavia pattern (SCA). In the present study it has been highlighted that: (1) there are several years (1986, 1987, 1992, 1995, 1997, 1999, 2004 and 2005) during which water in the IPC region is colder than the oceanic one remarking a weak or inexistent IPC during these Januaries and (2) three atmospheric patterns (N-D NAO, N-D EA/WR and N-D POL) are responsible of the main variability of the J SST in the IPC region of the western IP and only two indices (N-D EA/WR, N-D NAO) have shown to be significant to explain the variability of the J SST in the IPC region of the northern IP region.

  13. Inter-annual variation in characteristics of endozoochory by wild Japanese macaques.

    PubMed

    Tsuji, Yamato

    2014-01-01

    Endozoochory is important to the dynamics and regeneration of forest ecosystems. Despite the universality of inter-annual variation in fruit production, few studies have addressed the sign (seed predation versus seed dispersal) and strength (frequency and quantity) of fruit-frugivore interaction and the effectiveness of endozoochory in response to the long-term temporal context. In this study I evaluated the characteristics of endozoochorous dispersal by wild Japanese macaques Macaca fuscata inhabiting deciduous forest in northern Japan for five different years. I collected 378 fecal samples from the macaques in fall (September to November) and quantified the proportion of feces containing seeds, number of seeds per fecal sample, ratio of intact seeds, and seed diversity. The proportion of feces containing seeds of any species (five-year mean: 85.9%, range: 78-97%) did not show significant inter-annual variation, while species-level proportions did. The intact ratio of seeds (mean: 83%, range: 61-98%) varied significantly both between years and between months, and this varied among dominant plant species. The number of seeds per fecal sample (mean: 78, range: 32-102) varied monthly but did not between years, and the seed diversity (mean: 0.66, range: 0.57-0.81) did not show significant inter-annual variation, both of which were attributed to longer duration of macaques' gastro-intestinal passage time of seeds exceed their feeding bouts. This study demonstrated that frequency and success of seed dispersal over seed predation of macaque endozoochory showed inter-annual variation, indicating low specificity across the seed-macaque network. The temporal variability in the quality of seed dispersal may provide evidence of high resilience in response to fluctuating environmental conditions in the temperate forests. PMID:25272286

  14. Inter-Annual Variation in Characteristics of Endozoochory by Wild Japanese Macaques

    PubMed Central

    Tsuji, Yamato

    2014-01-01

    Endozoochory is important to the dynamics and regeneration of forest ecosystems. Despite the universality of inter-annual variation in fruit production, few studies have addressed the sign (seed predation versus seed dispersal) and strength (frequency and quantity) of fruit-frugivore interaction and the effectiveness of endozoochory in response to the long-term temporal context. In this study I evaluated the characteristics of endozoochorous dispersal by wild Japanese macaques Macaca fuscata inhabiting deciduous forest in northern Japan for five different years. I collected 378 fecal samples from the macaques in fall (September to November) and quantified the proportion of feces containing seeds, number of seeds per fecal sample, ratio of intact seeds, and seed diversity. The proportion of feces containing seeds of any species (five-year mean: 85.9%, range: 78–97%) did not show significant inter-annual variation, while species-level proportions did. The intact ratio of seeds (mean: 83%, range: 61–98%) varied significantly both between years and between months, and this varied among dominant plant species. The number of seeds per fecal sample (mean: 78, range: 32–102) varied monthly but did not between years, and the seed diversity (mean: 0.66, range: 0.57–0.81) did not show significant inter-annual variation, both of which were attributed to longer duration of macaques’ gastro-intestinal passage time of seeds exceed their feeding bouts. This study demonstrated that frequency and success of seed dispersal over seed predation of macaque endozoochory showed inter-annual variation, indicating low specificity across the seed–macaque network. The temporal variability in the quality of seed dispersal may provide evidence of high resilience in response to fluctuating environmental conditions in the temperate forests. PMID:25272286

  15. Mean SST bias and variability at inter-annual and decadal time-scales in CMIP5 models

    NASA Astrophysics Data System (ADS)

    Polo, Irene; Villamayor, Julian; Rodriguez-Fonseca, Belen; Mohino, Elsa; Losada, Teresa

    2016-04-01

    Analysis of model systematic errors in Sea Surface Temperature (SST) has generally focused on local processes and particular basins. Mean warm bias over the south subtropical upwelling systems in coupled models are largely studied and local cloud cover, alongshore winds and ocean stratification are pointed out as the responsible processes. Mean errors have impacts on the variability but this is less understood. In this study we try to understand the relation between mean global SST biases and how models perform the variability at different time-scales. To this end, we calculate the SST variability modes for 18 models in the preindustrial control CMIP5 experiment. We first analyse the seasonality of those modes and the inter-model differences. Associated parameters are confronted with the mean SST bias variability among models, thus we conclude how realistic models simulate the variability depending on the mean SST bias. Preliminary results suggest that models with cooler (warmer) that average SST mean bias over the southern hemisphere reproduce better (worse) the Inter-Decadal Pacific variability. Similar mean bias pattern has an effect on the skill for reproducing Pacific El Nino and Atlantic Nino modes. Finally an inter-model SST bias variability mode is found relating errors over the southern upwelling systems with cloud cover around 60S and equatorial precipitation shift. This mode is able to summarize some features in relation with inter-decadal to inter-annual variability in CMIP5 models and thus represents a potential tool to understand the wider picture in relation to SST biases and future projections.

  16. Seasonal and inter-annual changes in the planktonic communities of the northwest Alboran Sea (Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Mercado, Jesús M.; Cortés, Dolores; García, Alberto; Ramírez, Teodoro

    2007-08-01

    The response of the northwestern Alboran Sea pelagic ecosystem to temporal changes in hydrological conditions has been examined for the time period of 1992-2002. In addition, the bottom-up linkages between the lower trophic levels and the growth and nutritional status of sardine larvae were examined using quarterly data from 1992 to 2002 within the frame of the monitoring Project ECOMALAGA. The study area was characterised by the almost permanent presence of an upwelling which was intensified in the spring period. Consequently, an annual peak of nutrients was usually found during this season when the nitrate concentration averaged 1.35 μM. Accordingly, chlorophyll- a concentration and cell abundance of micro- plus nano-phytoplankton increased in that season (1.51 μg L -1 and 446 cell mL -1 compared to 0.85 μg L -1 and 225 cell mL -1 obtained from summer to fall). Despite these seasonal changes, the analysis of the taxonomic composition of the phytoplankton communities did not reveal a clear annual succession pattern. Contrastingly, peaks of zooplankton abundance were obtained in summer (1964 ind m -3) due to the increased presence of brachiopods with respect to copepods (which dominated from fall to spring). Significant inter-annual changes were obtained in the phytoplankton and zooplankton communities. Thus, dinoflagellate and coccolitophorid abundances relative to diatom abundances tended to increase from 1997 to 2002. This trend matched the progressive reduction of the upwelling intensity. These inter-annual changes significantly affected the larval growth of Sardine pilchardus and their nutritional condition, as higher growth rates in terms of body length coupled to higher somatic mass increases (expressed by DNA content) occurred in spring, matching with the higher chlorophyll- a concentration. Furthermore, the highest larval growth was obtained in 2001, coinciding with the change observed in the composition of phytoplankton community.

  17. Inter-annual climate variability and productivity models for grapevines in Portugal

    NASA Astrophysics Data System (ADS)

    Martinho, M.; Santos, J. A.; Malheiro, A. C.; Pinto, J. G.

    2009-09-01

    Grapevines are a major crop in Portugal, constituting an important source of income for local farmers. The Mediterranean type climate of the country strongly influences the growth and development of this crop, and ultimately the yield. Therefore, for several (9) Portuguese regions over 19 years (1986-2004), the inter-annual variability of grapevine productivity and climate data (mostly temperature and precipitation on a monthly basis) was analyzed in order to define mathematical models based on statistically significant correlations between those variables. One particular region (Vila Real, close to Demarcated Valley of Douro) was studied in more detail using the daily data available. For that purpose, a number of derived indices was calculated (e.g., number of days with positive minimum air temperature or maximum temperature above 25°C, number of days with precipitation higher than 10 mm). Close relationships between temperature, precipitation and relative air humidity were then found to influence productivity. In fact, a high-quality mathematical linear model based on these variables was found for Vila Real. Those analyses also enabled the verification of monthly climatic conditions, which are or not favorable for growth and development of grapevines; results indicate a clear relationship between the vegetative cycle of grapevines and their basic climatic requirements. After validation, this model may be used for predicting future yields in the region and, using data from an atmospheric model, it was also possible to project a future scenario for the productivity in the period (2030-2050), based on an specific emission scenario (A1B). Lastly, in order to isolate the large-scale atmospheric circulation patterns most favorable/unfavorable to wine productivity, years with extremely high (e.g., 1989) and extremely low yields (e.g., 1987) were selected and the corresponding dynamical conditions were analyzed in more detail.

  18. An improved estimation of the poleward expansion of coral habitats based on the inter-annual variation of sea surface temperatures

    NASA Astrophysics Data System (ADS)

    Takao, S.; Yamano, H.; Sugihara, K.; Kumagai, N. H.; Fujii, M.; Yamanaka, Y.

    2015-12-01

    The poleward expansion of coral habitats has been observed along the Japanese coast since the 1930s. Previous modeling studies have projected a poleward expansion using decadal-mean sea surface temperatures (SSTs) in the coldest months. However, this poleward expansion could be affected by the inter-annual variation of SST in the coldest months, which has not been considered before. In this study, the simulated pattern of poleward expansion was compared between cases where coral mortality was considered based on the inter-annual variation of SST and the decadal-mean SST in the coldest months. Modeled monthly mean SSTs for historical and future global warming simulations from the most recent climate projection model (MIROC4h) were used. The poleward expansion of corals simulated by considering mortality based on the inter-annual variation of SST in the coldest months better reproduced the observed poleward expansion speed compared to the simulations without such a consideration. Our results show the importance of considering coral mortality based on the inter-annual variation of seawater temperature to produce a more realistic poleward expansion of coral habitats.

  19. Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

    NASA Astrophysics Data System (ADS)

    Wilkinson, M.; Eaton, E. L.; Broadmeadow, M. S. J.; Morison, J. I. L.

    2012-12-01

    The carbon balance of an 80-yr-old deciduous oak plantation in the temperate oceanic climate of the south-east of Great Britain was measured by eddy covariance over 12 yr (1999-2010). The mean annual net ecosystem productivity (NEP) was 486 g C m-2 yr-1 (95% CI of ±73 g C m-2 yr-1), and this was partitioned into a gross primary productivity (GPP) of 2034 ± 145 g C m-2 yr-1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m-2 yr-1. Although the maximum variation of NEP between years was large (333 g C m-2 yr-1), the ratio of Reco/GPP remained relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular weather events, such as low summer solar radiation and low soil moisture content (values below 30% by volume). The European-wide heat wave and drought of 2003 did not reduce the NEP of this woodland because of good water supply from the surface-water gley soil. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p < 0.001) was found between peak leaf area index and annual GPP, which modified the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these two years. Inter-annual variation in the sensitivity of Reco to temperature was found to be strongly related to summer soil moisture content. The eddy covariance estimates of NEP closely matched mensuration-based estimates, demonstrating that this forest

  20. Seasonal and inter-annual variability of energy exchange above a boreal Scots pine forest

    NASA Astrophysics Data System (ADS)

    Launiainen, S.

    2010-12-01

    Twelve-years of eddy-covariance measurements conducted above a boreal Scots pine forest in Hyytiälä, Southern Finland, were analyzed to assess the seasonal and inter-annual variability of surface conductance (gs) and energy partitioning. The gs had distinct annual course, driven by the seasonal cycle of the Scots pine. Low gs (2-3 mm s-1 in April) cause the sensible heat flux to peak in May-June while evapotranspiration takes over later in July-August when gs is typically 5-7 mm s-1. Hence, during normal years Bowen ratio decreases from 4-6 in April to 0.7-0.9 in August. Sensitivity of gs to ambient vapor pressure deficit (D) was relatively constant but the reference value at D = 1 kPa varied seasonally and between years. Only two drought episodes when volumetric soil moisture content in upper mineral soil decreased below 0.15 m3 m-3 occurred during the period. Below this threshold value, transpiration was strongly reduced, which promoted sensible heat exchange increasing Bowen ratio to 3-4. Annual evapotranspiration varied between 218 and 361 mm and accounted between 50% and 90% of equilibrium evaporation. The forest floor contributed between 16 and 25% of the total evapotranspiration on annual scale. The fraction stayed similar over the observed range of environmental conditions including drought periods. The inter-annual variability of evapotranspiration could not be linked to any mean climate variable while the summertime sensible heat flux and net radiation were well explained by global radiation. The energy balance closure varied annually between 0.66 and 0.95 and had a distinct seasonal cycle with worse closure in spring when a large proportion of available energy is partitioned into sensible heat.

  1. Seasonal and inter annual variability of energy exchange above a boreal Scots pine forest

    NASA Astrophysics Data System (ADS)

    Launiainen, S.

    2010-08-01

    Twelve-years of eddy-covariance measurements conducted above a boreal Scots pine forest in Hyytiälä, Southern Finland, were analyzed to assess the seasonal and inter-annual variability of surface conductance (gs) and energy partitioning. The gs had distinct annual course, driven by the seasonal cycle of the Scots pine. Low gs (2-3 mm s-1 in April) restricted transpiration in springtime and caused the sensible heat flux to peak in May-June while evapotranspiration takes over later in July-August when gs is typically 5-7 mm s-1. Hence, during normal years Bowen ratio decreases from 4-6 in April to 0.7-0.9 in August. Sensitivity of gs to ambient vapor pressure deficit (D) was relatively constant but the reference value at D=1 kPa varied seasonally and between years. Only two drought episodes when volumetric soil moisture content in upper mineral soil decreased below 0.15 m3 m-3 occurred during the period. Below this threshold value transpiration was strongly reduced, which promoted sensible heat exchange increasing Bowen ratio to 3-4. Annual evapotranspiration varied between 218 and 361 mm and accounted between 50% and 90% of equilibrium evaporation. The forest floor contributed between 16 and 25% of the total evapotranspiration on annual scale. The fraction stayed similar over the observed range of environmental conditions including drought. The inter-annual variability of evapotranspiration could not be linked to any mean climate parameter while the summertime sensible heat flux and net radiation were well explained by global radiation. The energy balance closure varied annually between 0.66 and 0.95 and had a distinct seasonal cycle with worse closure in spring when large proportion of available energy is partitioned into sensible heat.

  2. Inter-annual variability of carbon exchange and extreme events at the Loobos pine forest

    NASA Astrophysics Data System (ADS)

    Elbers, Jan; Moors, Eddy; Hutjes, Ronald; Jacobs, Cor; Jans, Wilma; Kruijt, Bart; Stolk, Petra; ter Maat, Herbert; Vermeulen, Marleen; Abreu, Pedro

    2013-04-01

    Introduction At the seasonal to inter-annual time scale large variations in net uptake exist as a result of changing weather conditions. It is therefore important to investigate the inter-annual variability of the uptake of forests as accurately as possible and relate it to physiological and physical constraints of the biosphere-atmosphere system. Present model concepts on NEE are well capable to reproduce average conditions, however they fail to reproduce short term variations. If we are able to explain these variations this will help to improve explaining inter-annual variability. We analysed the impact of extremes on inter-annual variation observed in measurements of eddy-covariance fluxes over the years 1997-2012 over a mid-latitude pine forest in The Netherlands. To improve our understanding of these variations, we tried to quantify and make a distinction between variations caused by environmental conditions by means of ecosystem response curves for real and maximum response. We analysed the remaining variation by looking at changes in site conditions, such as aging and nitrogen availability and disturbances caused by abrupt events such as storms, frost, harvest, fire etc. Results Based on annual totals, the inter-annual variability in NEE is the result of variations in Reco and, to a lesser extent, GPP. There is no evidence that annual meteorological averages are the main drivers for inter-annual variation in observed NEE. Response functions However at a monthly time step there is a strong correlation between GPP and radiation and to a lesser extend with temperature and maximum vapour pressure deficit. The correlation with VPDmax reflects the strong control VPD has on the stomatal closure of this eco-system. Reco correlates best with air temperature, marginally better than with superficial soil temperature. Including superficial soil moisture in the function slightly increases the correlation. Fitted response curves show that non-stressed ecosystem

  3. Hydrological niche separation explains seasonal and inter-annual variations of vegetation dynamics in seasonally dry tropical forests

    NASA Astrophysics Data System (ADS)

    Xu, X.; Medvigy, D.; Powers, J. S.; Becknell, J. M.; Guan, K.

    2015-12-01

    Despite ample water supply, vegetation dynamics are subject to seasonal water stress in large fraction of tropical forests. These seasonally dry tropical forests (SDTFs) account for over 40% of tropical forests, harbor high biodiversity, have large potential carbon sink due to forest recovery from human disturbance and also play a critical role in global carbon budget and inter-annual variations. Plants in this biome display notably diverse responses to seasonal and inter-annual variations of water availability, especially inter-specific variations in canopy seasonality and biomass growth. Current process-based dynamic vegetation models cannot represent these diversities and are shown to perform poorly on simulating drought responses of tropical forests, calling into question of their ability to accurately simulate future changes in SDTFs. Accumulated field observations, suggest that hydrological niche separation driven by coordinated plant functional traits is associated with plants' performance under drought. Yet, it remains not clear whether the physiology-level hydrological niche separation can explain the ecosystem-level diversity observed in SDTFs. Here, we test the theory with a model-data fusion approach. We implemented a new plant hydrodynamic module that is able to track leaf water potential at sub-daily scale in ED2 model. We further incorporated a hydrological niche separation scheme based on a meta-data analysis of key functional traits in SDTFs. Simulated ecological patterns with and without hydrological niche separation were then compared with remote-sensing and long-term field observations from an SDTF site in Palo Verde, Costa Rica. Using several numerical experiments, we specifically examine the following questions: (i) Whether hydrological niche separation can explain the diversity in canopy seasonality and biomass growth? (ii) How important are the yet uncertain belowground functional traits, especially root profile in determining canopy

  4. Trend Change Detection in NDVI Time Series: Effects of Inter-Annual Variability and Methodology

    NASA Technical Reports Server (NTRS)

    Forkel, Matthias; Carvalhais, Nuno; Verbesselt, Jan; Mahecha, Miguel D.; Neigh, Christopher S.R.; Reichstein, Markus

    2013-01-01

    Changing trends in ecosystem productivity can be quantified using satellite observations of Normalized Difference Vegetation Index (NDVI). However, the estimation of trends from NDVI time series differs substantially depending on analyzed satellite dataset, the corresponding spatiotemporal resolution, and the applied statistical method. Here we compare the performance of a wide range of trend estimation methods and demonstrate that performance decreases with increasing inter-annual variability in the NDVI time series. Trend slope estimates based on annual aggregated time series or based on a seasonal-trend model show better performances than methods that remove the seasonal cycle of the time series. A breakpoint detection analysis reveals that an overestimation of breakpoints in NDVI trends can result in wrong or even opposite trend estimates. Based on our results, we give practical recommendations for the application of trend methods on long-term NDVI time series. Particularly, we apply and compare different methods on NDVI time series in Alaska, where both greening and browning trends have been previously observed. Here, the multi-method uncertainty of NDVI trends is quantified through the application of the different trend estimation methods. Our results indicate that greening NDVI trends in Alaska are more spatially and temporally prevalent than browning trends. We also show that detected breakpoints in NDVI trends tend to coincide with large fires. Overall, our analyses demonstrate that seasonal trend methods need to be improved against inter-annual variability to quantify changing trends in ecosystem productivity with higher accuracy.

  5. Twenty Years of High-Resolution Sea Surface Temperature Imagery around Australia: Inter-Annual and Annual Variability

    PubMed Central

    Foster, Scott D.; Griffin, David A.; Dunstan, Piers K.

    2014-01-01

    The physical climate defines a significant portion of the habitats in which biological communities and species reside. It is important to quantify these environmental conditions, and how they have changed, as this will inform future efforts to study many natural systems. In this article, we present the results of a statistical summary of the variability in sea surface temperature (SST) time-series data for the waters surrounding Australia, from 1993 to 2013. We partition variation in the SST series into annual trends, inter-annual trends, and a number of components of random variation. We utilise satellite data and validate the statistical summary from these data to summaries of data from long-term monitoring stations and from the global drifter program. The spatially dense results, available as maps from the Australian Oceanographic Data Network's data portal (http://www.cmar.csiro.au/geonetwork/srv/en/metadata.show?id=51805), show clear trends that associate with oceanographic features. Noteworthy oceanographic features include: average warming was greatest off southern West Australia and off eastern Tasmania, where the warming was around 0.6°C per decade for a twenty year study period, and insubstantial warming in areas dominated by the East Australian Current, but this area did exhibit high levels of inter-annual variability (long-term trend increases and decreases but does not increase on average). The results of the analyses can be directly incorporated into (biogeographic) models that explain variation in biological data where both biological and environmental data are on a fine scale. PMID:24988444

  6. Identification of Diurnal, Seasonal and Inter-Annual Variability Across SE Asian Field Observations of key Water Cycle Variables: Rainfall, net Radiation, Total Evaporation and River Discharge

    NASA Astrophysics Data System (ADS)

    Solera García, M. A.; Tych, W.; Chappell, N.

    2007-12-01

    The identification of periodic patterns in water cycle variables is critical to the understanding of land-atmosphere interactions, climate change and the evaluation of General Circulation Model (GCM) output. SE Asia in particular plays a very important role on the global climate because it is a large source of energy and water fluxes into the upper atmosphere. Cycle identification is carried out following the Data Based Mechanistic (DBM) philosophy, which focuses on the use of parsimonious, rigorous models which are characterised by lack of a priori assumptions, built in uncertainty analysis and final model acceptance dependent on the physical interpretation of the results. The DBM tool used here is the Unobserved Component - Dynamic Harmonic Regression (UC-DHR) model, which is a statistical method that allows the identification of variability in time series by introducing Time Variable Parameter (TVP) estimation of harmonic components. UC-DHR is not scale dependent and was thus applied to both hourly (to investigate diurnal variation) and fortnightly datasets (for intra- and inter-annual variability). The data used in the analysis has been gathered from existing catchment datasets for three regions of tropical SE Asia, namely Northern Thailand, Central Peninsular Malaysia and Northeast Borneo. These regions were chosen because they represent the hydro-climatic gradient (seasonal to equatorial) present within the tropics and because SE Asia has the most extensive set of catchment/plot studies within the humid tropics. Results show modeling tools were able to quantify the main patterns present in the observations throughout different time scales (diurnal, intra-annual and inter-annual) and the strength of the correlation pattern between the four hydro-climatic variables. The subsequent discussion focuses on the physical processes behind those patterns (e.g. diurnal variability caused by local convection due to solar heating; impact of El Niño Southern Oscillation

  7. Seasonal and inter-annual variation in ecosystem scale methane emission from a boreal fen

    NASA Astrophysics Data System (ADS)

    Rinne, Janne; Li, Xuefei; Raivonen, Maarit; Peltola, Olli; Sallantaus, Tapani; Haapanala, Sami; Smolander, Sampo; Alekseychik, Pavel; Aurela, Mika; Korrensalo, Aino; Mammarella, Ivan; Tuittila, Eeva-Stiina; Vesala, Timo

    2016-04-01

    Northern wetlands are one of the major sources of atmospheric methane. We have measured ecosystem scale methane emissions from a boreal fen continuously since 2005. The site is an oligotrophic fen in boreal vegetation zone situated in Siikaneva wetland complex in Southern Finland. The mean annual temperature in the area is 3.3°C and total annual precipitation 710 mm. We have conducted the methane emission measurements by the eddy covariance method. Additionally we have measured fluxes of carbon dioxide, water vapor, and sensible heat together with a suite of other environmental parameters. We have analyzed this data alongside with a model run with University of Helsinki methane model. The measured fluxes show generally highest methane emission in late summers coinciding with the highest temperatures in saturated peat zone. During winters the fluxes show small but detectable emission despite the snow and ice cover on the fen. More than 90% of the annual methane emission occurs in snow-free period. The methane emission and peat temperature are connected in exponential manner in seasonal scales, but methane emission does not show the expected behavior with water table. The lack of water table position dependence also contrasts with the spatial variation across microtopography. There is no systematic variation in sub-diurnal time scale. The general seasonal cycle in methane emission is captured well with the methane model. We will show how well the model reproduces the temperature and water table position dependencies observed. The annual methane emission is typically around 10 gC m‑2. This is a significant part of the total carbon exchange between the fen and the atmosphere and about twice the estimated carbon loss by leaching from the fen area. The inter-annual variability in the methane emission is modest. The June-September methane emissions from different years, comprising most of the annual emission, correlates positively with peat temperature, but not with

  8. Thermospheric inter-annual variability and its potential connection to ENSO and stratospheric QBO

    NASA Astrophysics Data System (ADS)

    Liu, Huixin

    2016-05-01

    Using a 46-year-long dataset of the thermospheric density during 1967-2012, we examined the inter-annual variability in the thermosphere at 400 km and its potential connection to El-Nino Southern Oscillation (ENSO) and stratospheric Quasi-Biennial Oscillation (QBO). Wavelet analysis reveals two major modes of the thermosphere inter-annual oscillation, with the slower mode having an average period of ~64 months and the faster mode of ~28 months. The slower mode bears high coherence with the ENSO during 1982-2012, while the faster mode is found to vary coherently with the QBO around 1972, 1982 and 2002. Further examination reveals that the coherence between QBO and the faster mode is significantly influenced by their common coherent variation with the solar flux, while high coherence between the slower mode and ENSO is much less contaminated. Therefore, we conclude that the 28-month periodicity in thermospheric density may be caused by both QBO and solar radiation, whereas the 64-month periodicity possibly arises mainly from ENSO processes, with little/small contribution from solar radiation.

  9. Understanding inter-annual displacements associated to loading in Southern Europe using geodetic techniques

    NASA Astrophysics Data System (ADS)

    Valty, P.; de Viron, O.; Panet, I.

    2012-12-01

    Over the last decades, the number and diversity of geodetic measurements has kept growing, now providing long time series of precise and independent measurements. Since 2002, the GRACE mission has been measuring the Earth's gravity field temporal variations, which are dominated by mass transfers associated to the water cycle. These water mass variations also cause the Earth's surface to deform, impacting the time series of horizontal or vertical displacements measured by GPS. Because they sense the total water content, from the surface to the depth, over long time spans, geodetic data provide unique information, that can improve our understanding of the water resources variations and how they are influenced by climate variations. In this context, we analyze the inter-annual variability common to GRACE, GPS and the loading models over Southern Europe, where a dense network of GPS permanent stations is available. First, we convert the GRACE geoids into their associated displacements and then, we isolate common inter-annual variability modes with the GPS data and the loading models by applying a Singular Value Decomposition (SVD). When analysing the spatial and temporal characteristics of these modes, we evidence the signature of extreme climatic events like the heatwaves of 2003 and 2007. We finally discuss these results in terms of hydrological signal and investigate the specific signature of the noticed critic climatic events in the geodetic time series.

  10. Seasonal and inter-annual variability of lower stratospheric age of air spectra

    NASA Astrophysics Data System (ADS)

    Ploeger, Felix; Birner, Thomas

    2016-08-01

    Trace gas transport in the lower stratosphere is investigated by analysing seasonal and inter-annual variations of the age of air spectrum - the probability distribution of stratospheric transit times. Age spectra are obtained using the Chemical Lagrangian Model of the Stratosphere (CLaMS) driven by ERA-Interim winds and total diabatic heating rates, and using a time-evolving boundary-impulse-response (BIER) method based on multiple tracer pulses. Seasonal age spectra show large deviations from an idealized stationary uni-modal shape. Multiple modes emerge in the spectrum throughout the stratosphere, strongest at high latitudes, caused by the interplay of seasonally varying tropical upward mass flux, stratospheric transport barriers and recirculation. Inter-annual variations in transport (e.g. quasi-biennial oscillation) cause significant modulations of the age spectrum shape. In fact, one particular QBO phase may determine the spectrum's mode during the following 2-3 years. Interpretation of the age spectrum in terms of transport contributions due to the residual circulation and mixing is generally not straightforward. It turns out that advection by the residual circulation represents the dominant pathway in the deep tropics and in the winter hemisphere extratropics above 500 K, controlling the modal age in these regions. In contrast, in the summer hemisphere, particularly in the lowermost stratosphere, mixing represents the most probable pathway controlling the modal age.

  11. The impact of inter-annual rainfall variability on food production in the Ganges basin

    NASA Astrophysics Data System (ADS)

    Siderius, Christian; Biemans, Hester; van Walsum, Paul; hellegers, Petra; van Ierland, Ekko; Kabat, Pavel

    2014-05-01

    Rainfall variability is expected to increase in the coming decades as the world warms. Especially in regions already water stressed, a higher rainfall variability will jeopardize food security. Recently, the impact of inter-annual rainfall variability has received increasing attention in regional to global analysis on water availability and food security. But the description of the dynamics behind it is still incomplete in most models. Contemporary land surface and hydrological models used for such analyses describe variability in production primarily as a function of yield, a process driven by biophysical parameters, thereby neglecting yearly variations in cropped area, a process driven largely by management decisions. Agricultural statistics for northern India show that the latter process could explain up to 40% of the observed inter-annual variation in food production in various states. We added a simple dynamic land use decision module to a land surface model (LPJmL) and analyzed to what extent this improved the estimation of variability in food production. Using this improved modelling framework we then assessed if and at which scale rainfall variability affects meeting the food self-sufficiency threshold. Early results for the Ganges Basin indicate that, while on basin level variability in crop production is still relatively low, several districts and states are highly affected (RSTD > 50%). Such insight can contribute to better recommendations on the most effective measures, at the most appropriate scale, to buffer variability in food production.

  12. Projecting pest population dynamics under global warming: the combined effect of inter- and intra-annual variations.

    PubMed

    Zidon, Royi; Tsueda, Hirotsugu; Morin, Efrat; Morin, Shai

    2016-06-01

    The typical short generation length of insects makes their population dynamics highly sensitive not only to mean annual temperatures but also to their intra-annual variations. To consider the combined effect of both thermal factors under global warming, we propose a modeling framework that links general circulation models (GCMs) with a stochastic weather generator and population dynamics models to predict species population responses to inter- and intra-annual temperature changes. This framework was utilized to explore future changes in populations of Bemisia tabaci, an invasive insect pest-species that affects multiple agricultural systems in the Mediterranean region. We considered three locations representing different pest status and climatic conditions: Montpellier (France), Seville (Spain), and Beit-Jamal (Israel). We produced ensembles of local daily temperature realizations representing current and future (mid-21st century) climatic conditions under two emission scenarios for the three locations. Our simulations predicted a significant increase in the average number of annual generations and in population size, and a significant lengthening of the growing season in all three locations. A negative effect was found only in Seville for the summer season, where future temperatures lead to a reduction in population size. High variability in population size was observed between years with similar annual mean temperatures, suggesting a strong effect of intra-annual temperature variation. Critical periods were from late spring to late summer in Montpellier and from late winter to early summer in Seville and Beit-Jamal. Although our analysis suggested that earlier seasonal activity does not necessarily lead to increased populations load unless an additional generation is produced, it is highly likely that the insect will become a significant pest of open-fields at Mediterranean latitudes above 40° during the next 50 years. Our simulations also implied that current

  13. Inter-annual variation of carbon uptake by a plantation oak woodland in south-eastern England

    NASA Astrophysics Data System (ADS)

    Wilkinson, M.; Eaton, E. L.; Broadmeadow, M. S. J.; Morison, J. I. L.

    2012-07-01

    The carbon balance of an 80 yr old deciduous oak plantation in the temperate oceanic climate of the south-east of Britain was measured by eddy covariance over 12 yr (1999-2010). The mean annual net ecosystem productivity (NEP) was 486 g C m-2 y-1 (95% CI of ±73 g C m-2 y-1), and this was partitioned into a Gross Primary Productivity (GPP) of 2034 ± 145 g C m-2 y-1, over a 165 (±6) day growing season, and an annual loss of carbon through respiration and decomposition (ecosystem respiration, Reco) of 1548 ± 122 g C m-2 y-1. The interannual variation of NEP was large (coefficient of variation (CV) 23%), although the variation for GPP and Reco was smaller (12%) and the ratio of Reco/GPP was relatively constant (0.76 ± 0.02 CI). Some anomalies in the annual patterns of the carbon balance could be linked to particular combinations of anomalous weather events, such as high summer air temperature and low soil moisture content. The Europe-wide heat-wave and drought of 2003 had little effect on the C balance of this woodland on a surface water gley soil. Annual variation in precipitation (CV 18%) was not a main factor in the variation in NEP. The inter-annual variation in estimated intercepted radiation only accounted for ~ 47% of the variation in GPP, although a significant relationship (p<0.001) was found between peak leaf area index and annual GPP which in turn played an important role in modifying the efficiency with which incident radiation was used in net CO2 uptake. Whilst the spring start and late autumn end of the net CO2 uptake period varied substantially (range of 24 and 27 days, respectively), annual GPP was not related to growing season length. Severe outbreaks of defoliating moth caterpillars, mostly Tortrix viridana L. and Operophtera brumata L., caused considerable damage to the forest canopy in 2009 and 2010, resulting in reduced GPP in these years.

  14. Inter-rater Reliability of Sustained Aberrant Movement Patterns as a Clinical Assessment of Muscular Fatigue

    PubMed Central

    Aerts, Frank; Carrier, Kathy; Alwood, Becky

    2016-01-01

    Background: The assessment of clinical manifestation of muscle fatigue is an effective procedure in establishing therapeutic exercise dose. Few studies have evaluated physical therapist reliability in establishing muscle fatigue through detection of changes in quality of movement patterns in a live setting. Objective: The purpose of this study is to evaluate the inter-rater reliability of physical therapists’ ability to detect altered movement patterns due to muscle fatigue. Design: A reliability study in a live setting with multiple raters. Participants: Forty-four healthy individuals (ages 19-35) were evaluated by six physical therapists in a live setting. Methods: Participants were evaluated by physical therapists for altered movement patterns during resisted shoulder rotation. Each participant completed a total of four tests: right shoulder internal rotation, right shoulder external rotation, left shoulder internal rotation and left shoulder external rotation. Results: For all tests combined, the inter-rater reliability for a single rater scoring ICC (2,1) was .65 (95%, .60, .71) This corresponds to moderate inter-rater reliability between physical therapists. Limitations: The results of this study apply only to healthy participants and therefore cannot be generalized to a symptomatic population. Conclusion: Moderate inter-rater reliability was found between physical therapists in establishing muscle fatigue through the observation of sustained altered movement patterns during dynamic resistive shoulder internal and external rotation. PMID:27347241

  15. Inter-annual changes of Biomass Burning and Desert Dust and their impact over East Asia

    NASA Astrophysics Data System (ADS)

    DONG, X.; Fu, J. S.; Huang, K.

    2014-12-01

    Impact of mineral dust and biomass burning aerosols on air quality has been well documented in the last few decades, but the knowledge about their interactions with anthropogenic emission and their impacts on regional climate is very limited (IPCC, 2007). While East Asia is greatly affected by dust storms in spring from Taklamakan and Gobi deserts (Huang et al., 2010; Li et al., 2012), it also suffers from significant biomass burning emission from Southeast Asia during the same season. Observations from both surface monitoring and satellite data indicated that mineral dust and biomass burning aerosols may approach to coastal area of East Asia simultaneously, thus have a very unique impact on the local atmospheric environment and regional climate. In this study, we first investigated the inter-annual variations of biomass burning and dust aerosols emission for 5 consecutive years from 2006-2010 to estimate the upper and lower limits and correlation with meteorology conditions, and then evaluate their impacts with a chemical transport system. Our preliminary results indicated that biomass burning has a strong correlation with precipitation over Southeast Asia, which could drive the emission varying from 542 Tg in 2008 to 945 Tg in 2010, according to FLAMBE emission inventory (Reid et al., 2009). Mineral dust also demonstrated a strong dependence on wind filed. These inter-annual/annual variations will also lead to different findings and impacts on air quality in East Asia. Reference: Huang, K., et al. (2010), Mixing of Asian dust with pollution aerosol and the transformation of aerosol components during the dust storm over China in spring 2007, Journal of Geophysical Research-Atmospheres, 115. IPCC (2007), Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, New York. Li, J., et al. (2012), Mixing of Asian mineral dust with anthropogenic pollutants over East Asia: a model case study of a super-duststorm in

  16. Multi-tissue analyses reveal limited inter-annual and seasonal variation in mercury exposure in an Antarctic penguin community.

    PubMed

    Brasso, Rebecka L; Polito, Michael J; Emslie, Steven D

    2014-10-01

    Inter-annual variation in tissue mercury concentrations in birds can result from annual changes in the bioavailability of mercury or shifts in dietary composition and/or trophic level. We investigated potential annual variability in mercury dynamics in the Antarctic marine food web using Pygoscelis penguins as biomonitors. Eggshell membrane, chick down, and adult feathers were collected from three species of sympatrically breeding Pygoscelis penguins during the austral summers of 2006/2007-2010/2011. To evaluate the hypothesis that mercury concentrations in penguins exhibit significant inter-annual variation and to determine the potential source of such variation (dietary or environmental), we compared tissue mercury concentrations with trophic levels as indicated by δ(15)N values from all species and tissues. Overall, no inter-annual variation in mercury was observed in adult feathers suggesting that mercury exposure, on an annual scale, was consistent for Pygoscelis penguins. However, when examining tissues that reflected more discrete time periods (chick down and eggshell membrane) relative to adult feathers, we found some evidence of inter-annual variation in mercury exposure during penguins' pre-breeding and chick rearing periods. Evidence of inter-annual variation in penguin trophic level was also limited suggesting that foraging ecology and environmental factors related to the bioavailability of mercury may provide more explanatory power for mercury exposure compared to trophic level alone. Even so, the variable strength of relationships observed between trophic level and tissue mercury concentrations across and within Pygoscelis penguin species suggest that caution is required when selecting appropriate species and tissue combinations for environmental biomonitoring studies in Antarctica. PMID:25085270

  17. Millennium-Scale Crossdating and Inter-Annual Climate Sensitivities of Standing California Redwoods

    PubMed Central

    Carroll, Allyson L.; Sillett, Stephen C.; Kramer, Russell D.

    2014-01-01

    Extremely decay-resistant wood and fire-resistant bark allow California’s redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI) helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE) have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood species have

  18. Millennium-scale crossdating and inter-annual climate sensitivities of standing California redwoods.

    PubMed

    Carroll, Allyson L; Sillett, Stephen C; Kramer, Russell D

    2014-01-01

    Extremely decay-resistant wood and fire-resistant bark allow California's redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI) helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE) have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood species have

  19. Inter-annual precipitation changes as quadratic signals in the GRACE time-variable gravity

    NASA Astrophysics Data System (ADS)

    Ogawa, R.; Chao, B. F.; Heki, K.

    2009-04-01

    The Gravity Recovery and Climate Experiment (GRACE) satellite mission has been producing scientific results on mass variations on inter-annual timescales, e.g. melting of ice sheet in Greenland and mountain glaciers in Alaska, Eastern Africa drought, water level increase in Caspian Sea, etc. In these discussions only linear trends and the seasonal components have been analyzed in the monthly GRACE time series, whereas little attention has been paid so far to the existence of the quadratic changes which signify the temporal accelerations. With over 6 years of GRACE data and revisiting the time-variable gravity field of various regions, we find that such acceleration/deceleration terms are quite often significantly different from zero. They include East Africa, near Obi River, Caspian Sea, Black Sea, Central Asia, and southern South America, whereof discussions of linear trends without specifying the epochs are inadequate. Here we investigate geophysical implication of these quadratic terms; in particular gravity changes in land areas reflect, to a large extent, soil moisture variations. Soil moisture is the time integration of water fluxes, i.e. precipitation, evapotranspiration and runoff. Here we consider that the linear trend in precipitation is responsible for the quadratic change in gravity, and examine trends of observed precipitation in various regions from CMAP (Climate Prediction Center Merged Analysis of Precipitation). Thus, in order to compare linear trend in CMAP and acceleration in GRACE, we calculate month-to-month difference of equivalent water depth at GRACE grid points, and modeled them with seasonal variations and linear trends. We found good agreement between their geographical distributions although amplitudes are smaller in GRACE, meaning the quadratic gravity changes in the GRACE data do reflect inter-annual changes of precipitation fairly faithfully.

  20. Growth response of temperate mountain grasslands to inter-annual variations of snow cover duration

    NASA Astrophysics Data System (ADS)

    Choler, P.

    2015-02-01

    A remote sensing approach is used to examine the direct and indirect effects of snow cover duration and weather conditions on the growth response of mountain grasslands located above the tree line in the French Alps. Time-integrated normalized difference vegetation index (NDVIint), used as a surrogate for aboveground primary productivity, and snow cover duration were derived from a 13 year long time series of the Moderate Resolution Imaging Spectro-radiometer (MODIS). A regional-scale meteorological forcing that accounted for topographical effects was provided by the SAFRAN-Crocus-MEPRA model chain. A hierarchical path analysis was developed to analyze the multivariate causal relationships between forcing variables and proxies of primary productivity. Inter-annual variations in primary productivity were primarily governed by year-to-year variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. A prolonged snow cover reduces the number and magnitude of frost events during the initial growth period but this has a negligeable impact on NDVIint as compared to the strong negative effect of a delayed snow melting. The maximum NDVI slightly responded to increased summer precipitation and temperature but the impact on productivity was weak. The period spanning from peak standing biomass to the first snowfall accounted for two thirds of NDVIint and this explained the high sensitivity of NDVIint to autumn temperature and autumn rainfall that control the timing of the first snowfall. The ability of mountain plants to maintain green tissues during the whole snow-free period along with the relatively low responsiveness of peak standing biomass to summer meteorological conditions led to the conclusion that the length of the snow-free period is the primary driver of the inter-annual variations in primary productivity of mountain grasslands.

  1. Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

    NASA Astrophysics Data System (ADS)

    Choler, P.

    2015-06-01

    A remote sensing approach is used to examine the direct and indirect effects of snow cover duration and weather conditions on the growth response of mountain grasslands located above the tree line in the French Alps. Time-integrated Normalized Difference Vegetation Index (NDVIint), used as a surrogate for aboveground primary productivity, and snow cover duration were derived from a 13-year long time series of the Moderate-resolution Imaging Spectroradiometer (MODIS). A regional-scale meteorological forcing that accounted for topographical effects was provided by the SAFRAN-CROCUS-MEPRA model chain. A hierarchical path analysis was developed to analyze the multivariate causal relationships between forcing variables and proxies of primary productivity. Inter-annual variations in primary productivity were primarily governed by year-to-year variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. A prolonged snow cover reduces the number and magnitude of frost events during the initial growth period but this has a negligible impact on NDVIint as compared to the strong negative effect of a delayed snow melting. The maximum NDVI slightly responded to increased summer precipitation and temperature but the impact on productivity was weak. The period spanning from peak standing biomass to the first snowfall accounted for two-thirds of NDVIint and this explained the high sensitivity of NDVIint to autumn temperature and autumn rainfall that control the timing of the first snowfall. The ability of mountain plants to maintain green tissues during the whole snow-free period along with the relatively low responsiveness of peak standing biomass to summer meteorological conditions led to the conclusion that the length of the snow-free period is the primary driver of the inter-annual variations in primary productivity of mountain grasslands.

  2. Immune function in a free-living bird varies over the annual cycle, but seasonal patterns differ between years.

    PubMed

    Hegemann, Arne; Matson, Kevin D; Both, Christiaan; Tieleman, B Irene

    2012-11-01

    A central hypothesis of eco-immunology proposes trade-offs between immune defences and competing physiological and behavioural processes, leading to immunological variation within and among annual-cycle stages, as has been revealed for some species. However, few studies have simultaneously investigated patterns of multiple immune indices over the entire annual cycle in free-living birds, and none has investigated the consistency of seasonal patterns across multiple years. We quantified lysis, agglutination, haptoglobin, leukocyte profiles, and body mass in free-living skylarks (Alauda arvensis) through two complete annual cycles and within and between four breeding seasons. The skylarks' annual cycle is characterised by annually repeated changes in energy and time budgets, social structure and diet. If trade-offs relating to these cyclic changes shape evolution, predictable intra-annual immune patterns may result. Alternatively, intra-annual immune patterns may vary among years if fluctuating environmental changes affect the cost-benefit balances of immune function. We found significant variation in immune indices and body mass across the annual cycle, and these patterns differed between years. Immune parameters differed between four breeding seasons, and in all years, lysis and agglutination increased as the season progressed independent of average levels. Population-level patterns (intra-annual, inter-annual, within breeding season) were consistent with within-individual patterns based on repeated measurements. We found little evidence for sex differences, and only haptoglobin was correlated (negatively) with body mass. We conclude that immune modulation is not simply a pre-programmed phenomenon that reflects predictable ecological changes. Instead, fluctuating environmental conditions that vary among years likely contribute to the immunological variation that we observed. PMID:22562421

  3. Inter-annual variability of the Mediterranean thermohaline circulation in Med-CORDEX simulations

    NASA Astrophysics Data System (ADS)

    Vittoria Struglia, Maria; Adani, Mario; Carillo, Adriana; Pisacane, Giovanna; Sannino, Gianmaria; Beuvier, Jonathan; Lovato, Tomas; Sevault, Florence; Vervatis, Vassilios

    2016-04-01

    Recent atmospheric reanalysis products, such as ERA40 and ERA-interim, and their regional dynamical downscaling prompted the HyMeX/Med-CORDEX community to perform hind-cast simulations of the Mediterranean Sea, giving the opportunity to evaluate the response of different ocean models to a realistic inter-annual atmospheric forcing. Ocean numerical modeling studies have been steadily improving over the last decade through hind-cast processing, and are complementary to observations in studying the relative importance of the mechanisms playing a role in ocean variability, either external forcing or internal ocean variability. This work presents a review and an inter-comparison of the most recent hind-cast simulations of the Mediterranean Sea Circulation, produced in the framework of the Med-CORDEX initiative, at resolutions spanning from 1/8° to 1/16°. The richness of the simulations available for this study is exploited to address the effects of increasing resolution, both of models and forcing, the initialization procedure, and the prescription of the atmospheric boundary conditions, which are particularly relevant in order to model a realistic THC, in the perspective of fully coupled regional ocean-atmosphere models. The mean circulation is well reproduced by all the simulations. However, it can be observed that the horizontal resolution of both atmospheric forcing and ocean model plays a fundamental role in the reproduction of some specific features of both sub-basins and important differences can be observed among low and high resolution atmosphere forcing. We analyze the mean circulation on both the long-term and decadal time scale, and the represented inter-annual variability of intermediate and deep water mass formation processes in both the Eastern and Western sub-basins, finding that models agree with observations in correspondence of specific events, such as the 1992-1993 Eastern Mediterranean Transient, and the 2005-2006 event in the Gulf of Lion. Long

  4. QBO Generated Inter-annual Variations of the Diurnal Tide in the Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.

    2004-01-01

    We report results from a study with the Numerical Spectral Model (NSM), which produces in the mesosphere significant inter-annual variations in the diurnal tide. Applying Hines Doppler Spread Parameterization (DPS), small-scale gravity waves (GW) drive the Quasi-biennial Oscillation (QBO) and Semi-annual Oscillation (SAO). With a GW source that peaks at the equator and is taken to be isotropic and independent of season, the NSM generates near the equator a QBO with variable periods around 27 months and zonal wind amplitudes close to 20 m / s at 30 Ism. As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. In the present paper it is shown that the QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. Since the period of the QBO is variable, its phase relative to the seasonal cycle changes. The magnitude of the QBO modulation of the tide thus varies considerably as our long-term model simulation shows. To shed light on the underlying mechanism, the relative importance of the linearized advection terms are discussed that involve the meridional and vertical winds of the diurnal tide.

  5. QBO Generated Inter-annual Variations of the Diurnal Tide in the Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.

    2004-01-01

    We report results from a study with the Numerical Spectral Model (NSM), which produces in the d i d tide significant inter-annual variations. Applying Hines' Doppler Spread Parameterization (DPS), small-scale gravity waves (GW) drive the Quasi-biennial Oscillation (QBO) and Semi-annual Oscillation (SAO). With a GW source that peaks at the equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 27 months and zonal wind amplitudes close to 20 m/s at 30 lan, As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. In the present paper it is shown that the QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. Since the period of the QBO is variable, its phase relative to the seasonal cycle changes. The magnitude of the QBO modulation of the tide thus varies considerably as our long-term model simulation shows. To shed light on the underlying mechanisms, we discuss (a) the relative importance of the linearized advection terms that involve the meridional and vertical winds of the diurnal tide and (b) the effects momentum deposition from GWs filtered by the QBO.

  6. Inter- and intra-annual variations of clumping index derived from the MODIS BRDF product

    NASA Astrophysics Data System (ADS)

    He, Liming; Liu, Jane; Chen, Jing M.; Croft, Holly; Wang, Rong; Sprintsin, Michael; Zheng, Ting; Ryu, Youngryel; Pisek, Jan; Gonsamo, Alemu; Deng, Feng; Zhang, Yongqin

    2016-02-01

    Clumping index quantifies the level of foliage aggregation, relative to a random distribution, and is a key structural parameter of plant canopies and is widely used in ecological and meteorological models. In this study, the inter- and intra-annual variations in clumping index values, derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) BRDF product, are investigated at six forest sites, including conifer forests, a mixed deciduous forest and an oak-savanna system. We find that the clumping index displays large seasonal variation, particularly for the deciduous sites, with the magnitude in clumping index values at each site comparable on an intra-annual basis, and the seasonality of clumping index well captured after noise removal. For broadleaved and mixed forest sites, minimum clumping index values are usually found during the season when leaf area index is at its maximum. The magnitude of MODIS clumping index is validated by ground data collected from 17 sites. Validation shows that the MODIS clumping index can explain 75% of variance in measured values (bias = 0.03 and rmse = 0.08), although with a narrower amplitude in variation. This study suggests that the MODIS BRDF product has the potential to produce good seasonal trajectories of clumping index values, but with an improved estimation of background reflectance.

  7. Climatic regulation of seasonal and inter-annual variability in net ecosystem exchange of CO2 on rangelands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Net ecosystem exchange of CO2 (NEE) from terrestrial ecosystems varies seasonally and inter-annually because of temporal variation in climate. If we are predict climate-caused variation in NEE, we must understand how climatic variation influences NEE and its components, CO2 uptake and CO2 loss. ...

  8. Impact of synoptic weather patterns and inter-decadal climate variability on air quality in the North China Plain during 1980-2013

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Ding, Aijun; Mao, Huiting; Nie, Wei; Zhou, Derong; Liu, Lixia; Huang, Xin; Fu, Congbin

    2016-01-01

    Potential relationships between air quality, synoptic weather patterns, and the East Asian Monsoon (EAM) over the North China Plain (NCP) were examined during the time period of 1980-2013 using a weather typing technique and ground-based air pollution index (API) data from three cities: Beijing, Tianjin and Shijiazhuang. Using the Kirchhofer method, circulation patterns during the 34-yr study period were classified into 5 categories, which were further used to understand the quantitative relationship between weather and air quality in NCP. The highest API values were associated with a stagnant weather condition when wide-spread stable conditions controlled most part of NCP, while westerly and southerly wind flowed over the northern and eastern part of this region, resulting in both the regional transport and local build-up of air pollutants. Under the continuous control of this weather pattern, API values were found to increase at a rate of 8.5 per day on average. Based on the qualitative and quantitative analysis, a significant correlation was found between the strength of EAM and inter-annual variability of frequencies of the weather patterns. The strengthening of summer/winter monsoon could increase the frequency of occurrence of cyclone/anticyclone related weather patterns. Time series of climate-induced variability in API over the 34 years were reconstructed based on the quantitative relationship between API and predominant weather patterns during 2001-2010. Significant connections between EAM and reconstructed API were found on both the inter-annual and inter-decadal scales. In winter and summer, strengthening/weakening of EAM, which was generally associated with the change of the representative circulation patterns, could improve/worsen air quality in this region.

  9. Inter-annual to inter-decadal streamflow variability in Quebec and Ontario in relation to dominant large-scale climate indices

    NASA Astrophysics Data System (ADS)

    Nalley, D.; Adamowski, J.; Khalil, B.; Biswas, A.

    2016-05-01

    The impacts of large-scale climate oscillations on hydrological systems and their variability have been documented in different parts of the world. Since hydroclimatic data are known to exhibit non-stationary characteristics, spectral analyses such as wavelet transforms are very useful in extracting time-frequency information from such data. As Canadian studies, particularly those of regions east of the Prairies, using wavelet transform-based methods to draw links between relevant climate indices [e.g., the El Niño Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), and the Pacific Decadal Oscillation (PDO)] and streamflow variability are not common, this study aims to analyze such relationships for the southern regions of Quebec and Ontario. Monthly and annual streamflow data with a record length of 55 years were used to capture streamflow variability at intra-annual, inter-annual and inter-decadal scales. The continuous wavelet transform spectra of monthly streamflow data revealed consistent significant 6- and 12-month periodicities, which are likely associated with strong seasonality factors. Its annual counterparts showed four different significant periodicities: up to 4 years, 4-6 years, 6-8 years, and greater than 8 years - all of which occurred after the late 1960s/early 1970s. Wavelet coherence analyses show that the influence of ENSO and NAO at the inter-annual scale occurs at 2-6 year periodicities, and the influence of PDO occur at periodicities up to 8 years and exceeding 16 years. Correlations between these climate indices and streamflow were computed to determine the time delay of streamflow response to the influence of ENSO, NAO, and PDO. The lag times ranged from 6-48 months (for monthly data) and 1-4 years (for annual data). This research contributes to our understanding of streamflow variability over the southern parts of Quebec and Ontario, and the role of ENSO, NAO, and PDO phenomena on this variability. These relationships can

  10. The inter-annual distribution of cloudless days and nights in Abastumani: Coupling with cosmic factors and climate change

    NASA Astrophysics Data System (ADS)

    Didebulidze, G. G.; Todua, M.

    2016-04-01

    We examined inter-annual variations and long-term trends of cloudless days (CD) and cloudless nights (CN) in 1957-1993 from Abastumani (41.75N, 42.82E), at different geomagnetic conditions and corresponding galactic cosmic rays (GCRs) flux changes. It showed possible influence of cosmic factors on cloud covering processes and, thus, climate change. It was demonstrated that (1) the inter-annual distribution of monthly mean values of planetary geomagnetic index Ap (for low and moderate disturbances) at CDs can be described by harmonic function with semiannual (with sharp maxima in March and September) and annual (with maximum in August) periodicities; (2) the inter-annual distribution of Ap index for CN has an additional maximum in June, where the largest decrease of GCR flux is observed. This phenomenon is expressed even stronger during Sudden Storm Commencement (SSC) events and strong geomagnetic disturbances (Ap≥50), when their relative numbers are the greatest and are accompanied by bigger reduction of GCRs flux; (3) the long-term trends of mean annual and mean seasonal values of Ap index and GCRs flux at CD and CN are estimated. It was detected that, for the latitudes of this region, long-term decreases (negative trends) of seasonal GCR flux are different at CD and CN, which could affect the radiative balance at the Earth's surface and, as a result, contribute to the climate change.

  11. Inter-annual variation of the surface temperature of tropical forests from SSM/I observations

    NASA Astrophysics Data System (ADS)

    Gao, H.; Fu, R.; Li, W.; Zhang, S.; Dickinson, R. E.

    2014-12-01

    Land surface temperatures (LST) within tropical rain forests contribute to climate variation, but observational data are very limited in these regions. In this study, all weather canopy sky temperatures were retrieved using the passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager/Sounder (SSMIS) over the Amazon and Congo rainforests. The remote sensing data used were collected from 1996 to 2012 using two separate satellites—F13 (1996-2009) and F17 (2007-2012). An inter-sensor calibration between the brightness temperatures collected by the two satellites was conducted in order to ensure consistency amongst the instruments. The interannual changes of LST associated with the dry and wet anomalies were investigated in both regions. The dominant spatial and temporal patterns for inter-seasonal variations of the LST over the tropical rainforest were analyzed, and the impacts of droughts and El Niños (on LST) were also investigated. The remote sensing results suggest that the morning LST is mainly controlled by atmospheric humidity (which controls longwave radiation) whereas the late afternoon LST is controlled by solar radiation.

  12. Graph-Based Inter-Subject Pattern Analysis of fMRI Data

    PubMed Central

    Takerkart, Sylvain; Auzias, Guillaume; Thirion, Bertrand; Ralaivola, Liva

    2014-01-01

    In brain imaging, solving learning problems in multi-subjects settings is difficult because of the differences that exist across individuals. Here we introduce a novel classification framework based on group-invariant graphical representations, allowing to overcome the inter-subject variability present in functional magnetic resonance imaging (fMRI) data and to perform multivariate pattern analysis across subjects. Our contribution is twofold: first, we propose an unsupervised representation learning scheme that encodes all relevant characteristics of distributed fMRI patterns into attributed graphs; second, we introduce a custom-designed graph kernel that exploits all these characteristics and makes it possible to perform supervised learning (here, classification) directly in graph space. The well-foundedness of our technique and the robustness of the performance to the parameter setting are demonstrated through inter-subject classification experiments conducted on both artificial data and a real fMRI experiment aimed at characterizing local cortical representations. Our results show that our framework produces accurate inter-subject predictions and that it outperforms a wide range of state-of-the-art vector- and parcel-based classification methods. Moreover, the genericity of our method makes it is easily adaptable to a wide range of potential applications. The dataset used in this study and an implementation of our framework are available at http://dx.doi.org/10.6084/m9.figshare.1086317. PMID:25127129

  13. Seasonal and inter-annual variability of dissolved inorganic nutrients along the western Antarctic Peninsula: is the Southern Annular Mode a potential driver?

    NASA Astrophysics Data System (ADS)

    Kim, H.; Martinson, D. G.; Iannuzzi, R. A.; Ducklow, H. W.

    2014-12-01

    We investigated long-term time series data to improve our understanding of phytoplankton bloom dynamics and its regulation by climate variability on the western Antarctic Peninsula (wAP). Specifically, we examined seasonal and inter-annual variability in utilization of three major inorganic nutrients (nitrate and nitrite, phosphate, silicate) by spring phytoplankton blooms and potential drivers responsible for shaping those variations, using a 20-year time series (1992-2012) near Palmer Station on the wAP. Seasonal and inter-annual covariability in the 50-m depth integrated nutrients and chlorophyll-a (Chl) was analyzed using principle component analysis. We found no linear trends in any of the nutrients or Chl, but there were strong year-to-year fluctuations in seasonal nutrient drawdown and phytoplankton blooms. On average, Chl peaked around days 290-310, stayed high for ca. 40 days, and gradually decreased to the end of the growing season (March-April). Nitrate and nitrite and phosphate behaved in the opposite way of chl-a indicating biological utilization by phytoplankton, but silicate was not utilized in all years, implying non-diatom blooms. Annual anomalies showed a cyclic pattern in Chl, with a maximum occurring every four to six years on average. These years were found to be associated with the negative phase of the Southern Annular Mode (SAM) in preceding winter. Our results suggest large-scale climate variability as a potential driver of biological utilization of nutrients and phytoplankton blooms.

  14. Inter-annual and inter-catchment variability of hydrologic partitioning: The importance of the Horton index to improve hydrologic predictions in a changing environment (Invited)

    NASA Astrophysics Data System (ADS)

    Troch, P. A.; Sivapalan, M.; Ruddell, B. L.; Brooks, P. D.; Durcik, M.; McGrath, G.

    2009-12-01

    In 1933, Horton analyzed the inter-annual variability of growing-season water balance components of the West Branch of the Delaware River at Hancock, NY, and discovered that the ratio of catchment vaporization to catchment wetting (the Horton index) remains almost constant despite large variability in precipitation. Eighty-six years later, Horton’s observation was confirmed using data from 431 MOPEX catchment in the US, but it was noted that the inter-annual variability of the Horton index depends strongly on the annual humidity index. It was also found that catchment vegetation use water more efficiently during drought years (lowest precipitation amount in 30 year record), suggesting that the convergence of biomes toward a common rain-use efficiency leaves a trace in the catchment water balance across climates. Recent work at the Hydrologic Synthesis Summer Institute at UBC, Vancouver, explored different simple top-down modeling approaches to investigate the observations related to the Horton index. All models were capable of predicting the mean Horton index with great accuracy, but were not able to fully explain the inter-annual variability. None of the models explicitly account for vegetation dynamics. It was also explored how knowledge of the Horton index in any given year can predict vegetation response (here measured by MODIS derived maximum NDVI), with surprisingly good results. Therefore, knowledge as to how precipitation is partitioned allows for improved predictions of vegetation response. This leads to an apparent paradox: how can it be that we predict the Horton index accurately with simple models that do not account for vegetation response, while knowledge of the Horton index predicts vegetation response? To resolve this paradox we used flux tower data from several Fluxnet stations across the country. The classic approach to model evapotranspiration (ET), which is based on the computation of a maximum ET rate and a soil moisture dependent reduction

  15. Global and regional methane budget and its inter-annual variability

    NASA Astrophysics Data System (ADS)

    Bourakkadi, Zakia; Payan, Sébastien; Locatelli, Robin; Chevallier, Frederic; Saunois, Marielle; Bousquet, Philippe

    2016-04-01

    Methane global concentration has more than doubled since the pre-industrial times. This increase is generally caused by the anthropogenic activities like the massive use and extraction of fossil fuel, rice paddies agriculture and emissions from landfills. Space observations are very useful to monitor and quantify methane concentration in the atmosphere, in order to improve our knowledge of its sources, sinks, transport and trends. Since 2002 global methane total-columns mixing ratois from the SCanning Imaging Absorption spectroMeter for Atmospheric ChartographY (SCIAMACHY) on board ENVISAT was the first space-borne sensitive to methane in the boundary layer. However the communication with the instrument was lost in April 2012. Since January 2009 methane columns retrievals have been available also from the Thermal And Near Infrared Sensor for carbon Observations-Fourier Transform Spectrometer (TANSO-FTS), on-board the GOSAT satellite. In this study, we used measurements in the short wave infrared radiation (SWIR) from TANSO-FTS covering 5 years, from January 2010 to December 2014 to estimate global methane fluxes by inverse modeling, using the PYVAR-LMDZ model. We present here the results of global and regional methane budget, and its inter-annual variability during this period.

  16. Inter-Annual and Decadal Changes in Tropospheric and Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

    Ziemke, Jr. R.; Chandra, S.

    2011-01-01

    Ozone data beginning October 2004 from the Aura Ozone Monitoring Instrument (OMI) and Aura Microwave Limb Sounder (MLS) are used to evaluate the accuracy of the Cloud slicing technique in effort to develop long data records of tropospheric and stratospheric ozone and studying their long-term changes. Using this technique, we have produced a 32-year (1979-2010) long record of tropospheric and stratospheric ozone from the combined Total Ozone Mapping Spectrometer (Toms) and OMI. The analyses of these time series suggest that the quasi-biennial oscillation (QBO) is the dominant source of inter-annual changes of 30-40 Dobson Units (DU). Tropospheric ozone also indicates a QBO signal in the peak to peak changes varying from 2 to 7 DU. Decadal changes in global stratospheric ozone indicate a turnaround in ozone loss around mid 1990's with most of these changes occurring in the Northern Hemisphere from the subtropics to high latitudes. The trend results are generally consistent with the prediction of chemistry climate models which include the reduction of ozone destroying substances beginning in the late 1980's mandated by the Montreal Protocol.

  17. Inter-annual variations of CO2 observed by commercial airliner in the CONTRAIL project

    NASA Astrophysics Data System (ADS)

    Sawa, Yousuke; Machida, Toshinobu; Matsueda, Hidekazu; Niwa, Yosuke; Umezawa, Taku

    2016-04-01

    Since 2005, we have conducted an observation program for greenhouse gases using the passenger aircraft of the Japan Airlines named Comprehensive Observation Network for TRace gases by AIrLiner (CONTRAIL). Over the past 10 years, successful operation of Continuous CO2 Measuring Equipment (CME) has delivered more than 6 million in-situ CO2 data from about 12000 flights between Japan and Europe, Australia, North America, or Asia. The large number of CME data enable us to well characterize spatial distributions and seasonal changes of CO2 in wide regions of the globe especially the Asia-Pacific regions. While the mean growth rates for the past 10 years were about 2 ppm/year, large growth rates of about 3 ppm/year were found in the wide latitudinal bands from 30S to 70N from the second half of 2012 to the first half of 2013. The multiyear data sets have the potential to help understand the global/regional CO2 budget. One good example is the significant inter-annual difference in CO2 vertical profiles observed over Singapore between October 2014 and October 2015, which is attributable to the massive biomass burnings in Indonesia in 2015.

  18. Inter- annual variability of water vapor over an equatorial coastal station using Microwave Radiometer observations.

    NASA Astrophysics Data System (ADS)

    Renju, Ramachandran Pillai; Uma, K. N.; Krishna Moorthy, K.; Mathew, Nizy; Raju C, Suresh

    The south-western region of the Indian peninsula is the gateway of Indian summer monsoon. This region experiences continuous monsoon rain for a longer period of about six months from June to November. The amount of water vapor variability is one of the important parameters to study the onset, active and break phases of the monsoon. Keeping this in view, a multi-frequency Microwave Radiometer Profiler (MRP) has been made operational for continuous measurements of water vapor over an equatorial coastal station Thiruvananthapuram (8.5(°) N, 76.9(°) E) since April 2010. The MRP estimated precipitable water vapor (PWV) for different seasons including monsoon periods have been evaluated by comparing with the collocated GPS derived water vapor and radiosonde measurements. The diurnal, seasonal and inter annual variation of water vapor has been studied for the last four years (2010-2013) over this station. The significant diurnal variability of water vapor is found only during the winter and pre-monsoon periods (Dec -April). The vertical distribution of water vapour is studied in order to understand its variability especially during the onset of monsoon. During the building up of south-west monsoon, the specific humidity increases to ˜ 10g/kg in the altitude range of 4-6 km and consistently maintained it throughout the active spells and reduces to below 2g/kg during break spells of monsoon. The instrument details and the results will be presented.

  19. Seasonal and inter-annual variations of community metabolism rates of a Posidonia oceanica seagrass meadow

    NASA Astrophysics Data System (ADS)

    Champenois, W.; Borges, A. V.

    2012-04-01

    We report gross primary production (GPP), community respiration (CR), and net community production (NCP) over Posidonia oceanica meadow at 10 m in Corsica (Bay of Revellata) based on the open water O2 mass balance from a data-set of hourly measurements with an array of three O2 optodes deployed from August 2006 to October 2009. The method was checked by comparison with discrete measurements of metabolic rates derived from benthic chamber incubations also based on the diel change of O2. This comparison was satisfactory and actually highlights the potential caveats of benthic incubation measurements related to O2 accumulation in small chambers leading to photorespiration, and an under-estimation of GPP. Our data confirmed previous P. oceanica meadows GPP and CR values, strong seasonal variations, and net autotrophy. High resolution data revealed strong inter-annual variability, with a decrease of GPP by 35% and NCP by 87% during 2006-2007 characterized by a mild and less stormy winter compared 2007-2008 and 2008-2009. P. oceanica meadows are then expected to decrease export of organic carbon to adjacent communities (decrease of NCP), since a decrease in frequency and intensity of marine storms is expected in future in the Mediterranean Sea, due to a northward shift of the Atlantic storm track.

  20. Identifying driving climate factors of wheat and maize yields inter-annual variability in France

    NASA Astrophysics Data System (ADS)

    Ceglar, Andrej; Toreti, Andrea; Lecerf, Remi; Dentener, Frank J.

    2015-04-01

    A canonical powered Partial Least Squares Regression (PLSR) approach is here used to estimate the relationship between meteorological variables and crop (durum wheat and grain maize) yield time series over France. This method combines the advantages of both the Canonical Correlation Analysis (CCA) and the PLSR. The latter is mainly based on the extraction of a subset of latent variables (having the best predictive power) from the full set of predictors. The method is applied to detrended (by using a LOESS approach) time series of crop yields and monthly mean temperature, cumulated precipitation and global solar radiation during the growing seasons from 1990 to 2011. Results show that, overall, temperature has a substantial influence on winter wheat yields in south-western and eastern France, while rainfall plays an important role in the northern and southern parts of the country. Finally, radiation is more important over the southern part of France. Concerning grain maize, the inferred statistical models show relatively low skill over the northern part of France, where inter-annual yield variability is low. Overall, results show that temperature is the most important variable influencing grain maize yields over the southern and eastern parts of France, while rainfall is more important in the central and northern parts of the country. Finally, global radiation is the main meteorological factor over the westernmost part of France.

  1. A constructive inter-track interference coding scheme for bit-patterned media recording system

    NASA Astrophysics Data System (ADS)

    Arrayangkool, A.; Warisarn, C.; Kovintavewat, P.

    2014-05-01

    The inter-track interference (ITI) can severely degrade the system performance of bit-patterned media recording (BPMR). One way to alleviate the ITI effect is to encode an input data sequence before recording to avoid some data patterns that easily cause an error at the data detection process. This paper proposes a constructive ITI (CITI) coding scheme for a multi-track multi-head BPMR system to eliminate the data patterns that lead to severe ITI. Numerical results indicate that the system with CITI coding outperforms that without CITI coding, especially when an areal density (AD) is high and/or the position jitter is large. Specifically, for the system without position jitter at bit-error rate of 10-4, the proposed scheme can provide about 3 dB gain at the AD of 2.5 Tb/in.2 over the system without CITI coding.

  2. Modeling the Observed QBO and Inter-Annual Variations of the Diurnal Tide in the Mesosphere

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.; Huang, F. T.

    2006-01-01

    In the current version of the Numerical Spectral Model (NSM), the Quasi-biennial Oscillation (QBO) is generated primarily by small-scale gravity waves (GW) from Hines' Doppler Spread Parameterization (DSP). The model does not have topography, and the planetary waves are solely generated by instabilities. We discuss a 3D modeling study that describes the QBO extending from the stratosphere into the upper mesosphere, where the oscillation produces significant inter-annual variations in the diurnal tide. The numerical results are compared with temperature measurements from the SABER (TIMED) and MLS (UARS) instruments obtained by Huang et al. (2006). With a GW source that peaks at the Equator and is taken to be isotropic and independent of season, the NSM generates a QBO with variable periods around 26 months and zonal wind amplitudes of almost 25 m/s at 30 km. As reported earlier, the NSM reproduces the observed equinoctial maxima in the diurnal tide at altitudes around 95 km. The modeled QBO modulates the tide such that the seasonal amplitude maxima can vary from one year to another by as much as 30%. To shed light on the underlying mechanisms, the relative importance of the advection terms are discussed, and they are shown to be important in the stratosphere. At altitudes above 80 km, however, the QBO-related inter-annual variations of the tide are generated primarily by GW momentum deposition. In qualitative agreement with the SABER measurements, the model generates distinct zonal-mean QBO temperature variations in the stratosphere and mesosphere. In the stratosphere, the computed amplitudes are not much smaller than those observed, and the rate of downward propagation at the Equator is reproduced. The modeled temperature amplitudes in the mesosphere, however, are much smaller than those observed. The observed and computed temperature variations of the QBO peak at the Equator but extend with phase reversals to high latitudes, in contrast to the zonal winds that are

  3. Spatio-temporal variation of methane over Indian region: Seasonal and inter-annual variation .

    NASA Astrophysics Data System (ADS)

    M, K.; Nair, P. R.

    2015-12-01

    Methane (CH4) has an important role in the radiation budget and chemistry in the lower and middle atmosphere as a greenhouse and reactive trace gas. The rapid developments in the agriculture and industry over India have lead to the emission of many pollutants like CO, O3, CH4, CO2, SO2 etc into the atmosphere. However, their sources, sinks and concentration levels are poorly understood because of the lack of systematic sampling and monitoring. The advent of satellite remote sensing has helped to analyze the chemical composition of atmosphere with good spatial coverage especially over tropical region which was poorly sampled with the existing surface network. This work attempts an analysis of spatial distribution, seasonal cycle and inter annual variation of CH4 over Indian region during 2003-2009 using SCIAMACHY data onboard ENVISAT. Column CH4 varies from 1740-1890 ppbv over Indian region with distinct spatial and temporal features. We observed a dependence of seasonal CH4 variation on rice cultivation, convective activities and changes in boundary layer characteristics. The comparative study using satellite, aircraft and surface measurement shown CH4 has non-homogeneity in its distribution and seasonal variation in different layers of atmosphere. A comparative study of CH4 at different hot spot regions over the globe was carried out which showed prominent hemispherical variations. Large spread in column CH4 was observed at India and Chinese region compared to other regions with a significant seasonal variability. This study points to the blending of satellite, aircraft and surface measurements for the realization of regional distribution of CH4.

  4. Evaluation of two GCMs in simulating rainfall inter-annual variability over Southern Africa

    NASA Astrophysics Data System (ADS)

    Klutse, Nana Ama Browne; Abiodun, Babatunde J.; Hewitson, Bruce C.; Gutowski, William J.; Tadross, Mark A.

    2016-02-01

    We evaluate the performance of two global circulation models (GCMs) over Southern Africa, as part of the efforts to improve the skill of seasonal forecast from a multi-model ensemble system over the region. The two GCMs evaluated in the study are the Community Atmosphere Model version 3 (CAM3) and the Hadley Centre Atmospheric Model version 3 (HadAM3). The study analyzed 30-year climate simulations from the models and compared the results with those from Climate Research Unit (CRU) and National Center for Environmental Prediction (NCEP) reanalysis dataset. The evaluation focused on how well the models simulate circulation features, seasonal variation of temperature and rainfall, and the inter-annual rainfall and circulations during El Niño Southern Oscillation (ENSO) years. The study also investigated the relationship between the regional rainfall from the models and global sea surface temperature (SST) during the El Niño and La Niña years. The results show that both GCMs simulate the circulation features and the seasonal cycles of rainfall and temperature fairly well. The location and magnitude of maxima and minima in surface temperature, sea level pressure (SLP), and rainfall fields are well reproduced. The maximum error in the simulated temperature fields is about 2 °, 4 mb in SLP and 8 mm/day in rainfall. However, CAM3 shows a major bias in simulating the summer rainfall; it simulates the maximum rainfall along the western part of Southern Africa, instead of the eastern part. The phase of the seasonal cycles is well reproduced, but the amplitude is underestimated over the Western Cape. Both CAM3 and HadAM3 give reasonable simulations of significant relationship between the regional rainfall and SST over the Nino 3.4 region and show that ENSO strongly drives the climate of Southern Africa. Hence, the model simulations could contribute to understanding the climate of the region and improve seasonal forecasts over Southern Africa.

  5. Sea surface temperature in False Bay (South Africa): Towards a better understanding of its seasonal and inter-annual variability

    NASA Astrophysics Data System (ADS)

    Dufois, François; Rouault, Mathieu

    2012-07-01

    Two sea surface temperature (SST) products, Pathfinder version 5.0 and MODIS/TERRA are evaluated and used to study the seasonal and the inter-annual variability of sea surface temperature (SST) together with local SST and wind data in the vicinity of False Bay (Western Cape, South Africa). At the monthly scale, differences of up to 3 °C are detected between the two products in the bay. In the northern half of the bay, SST is fairly well explained by seasonality. In contrast, the southern half exhibits a higher inter-annual variability in SST. The southern half of the bay and the Western Cape upwelling system (Cape Agulhas to Cape Columbine) share most of their variance. Furthermore, the inter-annual variability of SST in False Bay is correlated with both the Niño 3.4 index and local wind speed anomalies. El Niño (La Niña) events induce an equatorward (poleward) shift in the South Atlantic High pressure system leading to a weakening (strengthening) of upwelling favourable south-easterly. Those changes induce a warm (cold) SST anomaly along the West Coast of Southern Africa.

  6. Topographic control of snowpack distribution in a small catchment in the central Spanish Pyrenees: intra- and inter-annual persistence

    NASA Astrophysics Data System (ADS)

    Revuelto, J.; López-Moreno, J. I.; Azorin-Molina, C.; Vicente-Serrano, S. M.

    2014-04-01

    In this study we analyzed the relations between terrain characteristics and snow depth distribution in a small alpine catchment located in the central Spanish Pyrenees. Twelve field campaigns were conducted during 2012 and 2013, which were years characterized by very different climatic conditions. Snow depth was measured using a long range terrestrial laser scanner and analyses were performed at a spatial resolution of 5 m. Pearson's r correlation, multiple linear regressions and binary regression trees were used to analyze the influence of topography on the snow depth distribution. The analyses were used to identify the topographic variables that better explain the snow distribution in this catchment, and to assess whether their contributions were variable over intra- and inter-annual time scales. The topographic position index, which has rarely been used in these types of studies, most accurately explained the distribution of snow accumulation. Other variables affecting the snow depth distribution included the maximum upwind slope, elevation, and northing (or potential incoming solar radiation). The models developed to predict snow distribution in the basin for each of the 12 survey days were similar in terms of the most explanatory variables. However, the variance explained by the overall model and by each topographic variable, especially those making a lesser contribution, differed markedly between a year in which snow was abundant (2013) and a~year when snow was scarce (2012), and also differed between surveys in which snow accumulation or melting conditions dominated in the preceding days. The total variance explained by the models clearly decreased for those days on which the snow pack was thinner and more patchily distributed. Despite the differences in climatic conditions in the 2012 and 2013 snow seasons, some similarities in snow accumulation patterns were observed.

  7. Diurnal, Seasonal and Inter-annual Variations of N2O Fluxes from Perennial Vineyard Soils in California, USA.

    NASA Astrophysics Data System (ADS)

    Suddick, E. C.; Carlisle, E. A.; Spencer, R. G.; Smart, D. R.

    2007-12-01

    The USA emits 1562 million metric tons of carbon equivalents a year, whereby this value is projected to rise by an estimated 14 % in 2012. California is the 12th major global emitter of greenhouse gases, emitting approximately 500 million metric tons of carbon equivalents a year. 84 % of greenhouse gas emissions are from CO2, 7 % and 6 % from N2O and CH4 respectively and approximately 8 % of these emissions are derived from agricultural activities. The concentration of nitrous oxide (N2O) within the atmosphere has been increasing at a rate of approximately 0.27 % per year and has mainly been attributed to agricultural practices such as land-use changes, biomass burning, nitrogen fertilization, livestock and manure management. Agriculture related activities generate from 6 to 35 Tg N2O-N per year, or about 60 to 70 % of global production. The primary biogenic sources of N2O are from terrestrial soils, which are thought to be a major source of N2O to the atmosphere and mainly involve the microbial nitrogen transformations brought about by nitrification and denitrification. The aim of this study was to quantify the seasonal and inter-annual variability of N2O emissions and nitrogen cycling from a conventionally tilled wine grape vineyard in Napa, California during a two year closed static chamber study and to also investigate the diurnal N2O flux pattern and effects of fertilization management practices on emissions within a table grape vineyard in Delano, California. Preliminary data shows that the annual N2O fluxes were influenced by soil properties, management practices and weather such as precipitation events where increases in N2O emissions were observed after irrigation or fertilization practices and immediately following rainfall. Vineyard floor and vine management will be discussed in terms of the significance management practices have upon the release of N2O emissions from vineyard soils where the high water and nitrogen fertilizer usage within these

  8. The NMME Intra-Seasonal to Inter-Annual Prediction Experiment (Invited)

    NASA Astrophysics Data System (ADS)

    Kirtman, B. P.

    2013-12-01

    The recent US National Academies report 'Assessment of Intraseasonal to Interannual Climate Prediction and Predictability' was unequivocal in recommending the need for the development of a North American Multi-Model Ensemble (NMME) operational predictive capability. Indeed, this effort is required to meet the specific tailored regional prediction and decision support needs of a large community of climate information users. The multi-model ensemble approach has proven extremely effective at quantifying prediction uncertainty due to uncertainty in model formulation, and has proven to produce better prediction quality (on average) then any single model ensemble. Given the pragmatic utility of the multi-model approach, there is multi-agency (NOAA, NSF, NASA, and DOE) support for a North American Multi-Model Ensemble (NMME) Intra- seasonal to Seasonal to Inter-annual (ISI) prediction experiment. This experiment leverages an NMME team that has already formed and began producing routine real-time multi-model ensemble ISI predictions since August 2011. The forecasts are provided to the NOAA Climate Prediction Center (CPC) on an experimental basis for evaluation and consolidation as a multi-model ensemble ISI prediction system. The experimental prediction system developed by this NMME team is as an 'NMME of opportunity' in that the seasonal-to-interannual prediction systems are readily available and each team member has independently developed the initialization and prediction protocol. We will refer to the NMME of opportunity as phase 1 NMME (or NMME-1). The NMME-1 focuses on season-to-interannual time-scales in that the data that is exchanged is monthly. Here we show some results from 28 years of hindcasts that cover a common period (i.e., 1982-2009) for all the models, and the real-time experimental forecast from the NMME of opportunity (i.e., NMME-1). The results help provide evidence of the benefit of a multi-model ensemble of predictions, as compared with the ensemble

  9. Seasonal to Inter-annual Variability of the Atlantic Ocean Carbon Sink

    NASA Astrophysics Data System (ADS)

    Landschützer, Peter; Schuster, Ute; Bakker, Dorothee; Gruber, Nicolas

    2013-04-01

    The Atlantic Ocean is one of the most important sinks for atmospheric carbon dioxide (CO2), but this sink is known to vary substantially from seasonal to multi-decadal time scales. Here we use observations of the surface ocean partial pressure of CO2 (pCO2) to estimate this sink and its temporal variations on a monthly basis from 1998 through 2007. We benefitted (i) from a continuous strengthening of the observational underway network and (ii) from an improved technique to interpolate the data in space and time. In particular, we combine two artificial neural network methods to reconstruct basin-wide monthly maps of the sea surface pCO2 at a resolution of 1° latitude x 1° longitude. From those, we then compute air-sea CO2 flux maps using a standard gas exchange parameterization and high-resolution wind speeds. The evaluation of our estimates with independent time series data demonstrates that our method reconstructs the seasonal signal at these independent stations well. We estimate a decadal mean flux of 0.45±0.16 PgC*yr-1 for the Atlantic region from 44° S to 79° N and west of 30° E, which is in good agreement with recent studies. We find the strongest seasonal variability of the sea surface pCO2 and the CO2 air-sea fluxes within the subtropics of the northern and southern hemisphere, i.e. the zones where the seasonal cycle of the sea surface pCO2 is thermally driven. Trends in sea surface pCO2 suggest the strongest increase from 1998 to 2007 polewards of 40° N along the Gulf Stream, the North Atlantic Current and the Subpolar Gyre leading to a decreasing ocean carbon sink, whilst temporal trends in the South Atlantic show an increasing sink. Our results show that the air-sea flux shows only small inter-annual variability of 0.04 PgC*yr-1, with low variability both in the South Atlantic (0.02 PgC *yr-1) and the North Atlantic (0.02 PgC *yr-1).

  10. Phenological controls on inter-annual variability in ozone dry deposition velocity

    NASA Astrophysics Data System (ADS)

    Clifton, Olivia; Fiore, Arlene; Munger, J. William; Shevliakova, Elena; Horowitz, Larry; Malyshev, Sergey; Griffin, Kevin

    2016-04-01

    Our understanding of ozone removal by northern mid-latitude temperate deciduous forests is largely based on short-term observational studies, and thus year-to-year variations of this sink have received little attention. The specific pathways for ozone dry deposition include stomatal uptake and other non-stomatal processes that are poorly understood. Given the importance of ozone dry deposition to model accurately the tropospheric ozone budget and regional air quality, an improved mechanistic understanding of this ozone sink is needed. We investigate here the physical and biological controls on inter-annual variations in seasonal and diurnal cycles of ozone dry deposition velocity using nine years of hourly observations of eddy covariance ozone flux and concentration measurements at Harvard Forest, a northern mid-latitude temperate deciduous forest. We also use coincident eddy covariance water vapor flux and sensible heat flux and other micrometeorological measurements to infer stomatal conductance in order to separate the impacts of stomatal versus non-stomatal pathways on ozone deposition. There is a difference of approximately a factor of two between minimum and maximum monthly daytime mean ozone dry deposition velocities at Harvard Forest. The highest summertime mean ozone dry deposition velocities occur during 1998 and 1999 (0.72 cm/s), and similar seasonal and diurnal cycles occur in both years. The similar dry deposition velocities during these two years, however, may reflect compensation between different processes as mean daytime summertime stomatal conductance during 1998 is roughly 1.5 times higher than for 1999, suggesting large year-to-year variations in non-stomatal as well as stomatal uptake of ozone. We partition the onset and decline of the growing season each year into different periods using spring and fall phenology observations at Harvard Forest. Combining the dry deposition velocities across years during each phenological period, we find that

  11. Intra- and Inter-annual Fluorescence Intensity Variations in Drip Water, Heshang Cave, Central China: Implications for Speleothem Palaeoclimatology

    NASA Astrophysics Data System (ADS)

    Jin, L.; Hu, C.; Li, X.; Ruan, J.; Hartland, A.

    2015-12-01

    Cave drip water acts as a signal carrier for the soil-rock-air system leading to the capture of climatic and environmental information in stalagmites. This paper seeks to develop an understanding of the environmental and climatic factors which control fluorescence variations in dripwater from in Heshang Cave, Central China. This information is essential to unravelling the significance of organic fluorescence in stalagmites and its utility in quantitative paleoclimate reconstructions. On the seasonal time scale, drip water fluorescence is largely controlled by the decomposition and translocation of dissolved organic matter in the soil, related to climate factors like temperature and precipitation. On the inter-annual time scale, longer duration monitoring data in scarce, yet this is needed to fully comprehend the influence of climate in stalagmite fluorescence time series. This study presents nine consecutive years of monthly drip water fluorescence intensity and drip rate data from two perennial drip sites in Heshang Cave. Drip water fluorescence was generally characterized by intensities in spring/summer and low intensities in autumn/winter. In dry hydrologic years, little seasonality in fluorescence signals was observed, but the opposite was observed in wet years. On the inter-annual time scale, the annual mean intensities of drip water fluorescence positively correlated with local annual rainfall with a 1-year lag (R2HS4=0.94; R2HS6=0.74). This indicates that rainfall is the main control on total drip water fluorescence (integrating across a hydrologic year), despite significant degrees of intra-annual fluorescence variation being observed between wet and dry years. These findings are of direct relevance for paleoclimate reconstruction using fluorescence intensities in stalagmites from the Asian monsoon region. Key words: fluorescence; dissolved organic matter; drip water rates; seasonality; precipitation

  12. Modeling Inter-annual Variability of Seasonal Evaporation and Storage Change Based on the Extended Budyko Framework

    NASA Astrophysics Data System (ADS)

    Chen, X.; Alimohammadi, N.; Wang, D.

    2013-12-01

    Long-term climate is the first order control on mean annual water balance, and vegetation and the interactions between climate seasonality and soil water storage change have also been found to play important roles. The purpose of this paper is to extend the Budyko hypothesis to the seasonal scale and to develop a model for inter-annual variability of seasonal evaporation and storage change. A seasonal aridity index is defined as the ratio of potential evaporation to effective precipitation, where effective precipitation is the difference between rainfall and storage change. Correspondingly, evaporation ratio is defined as the ratio of evaporation to effective precipitation. A modified Turc-Pike equation with a horizontal shift is proposed to model inter-annual variability of seasonal evaporation ratio as a function of seasonal aridity index, which includes rainfall seasonality and soil water change. The performance of the seasonal water balance model is evaluated for 277 watersheds in the United States. 99% of wet seasons and 90% of dry seasons have Nash-Sutcliffe efficiency coefficients larger than 0.5. The developed seasonal model can be applied for constructing long-term evaporation and storage change data when rainfall, potential evaporation, and runoff observations are available. On the other hand, vegetation affects seasonal water balance by controlling both evaporation and soil moisture dynamics. The correlation between NDVI and evaporation is strong particularly in wet seasons. However, the correlation between NDVI and the seasonal model parameters is only strong in dry seasons.

  13. Linking in-stream nutrient flux to land use and inter-annual hydrological variability at the watershed scale.

    PubMed

    Aguilera, Rosana; Marcé, Rafael; Sabater, Sergi

    2012-12-01

    The significance of nutrient inputs at the watershed scale is best expressed in terms of in-stream processes, compared to evaluating simple field measurements of nutrient inputs. Modeling tools are necessary to consider the complexity of river networks in the determination of the sources and processes by which nutrients are transported at the watershed scale. Mediterranean rivers are potentially vulnerable to climate change (decrease in precipitation and increase of extreme events), and identifying and quantifying nutrient pollution sources and their spatial distribution can improve water resource management at the watershed scale. We apply a hybrid process-based and statistical model (SPARROW, spatially referenced regression on watershed attributes) to a largely disturbed Mediterranean watershed in NE Spain in order to estimate the annual nitrate and phosphate loads reaching the drainage network. The model emphasized the contribution of in-stream processes in nutrient transport and retention, and the inter-annual (7 years) effects of hydrological variability on the export of nutrients from the landscape to water bodies. Although forest and grassland land cover types predominate, agricultural activities and human agglomerations were significant sources of nutrient enrichment. Nutrient flux apportionment was also linked to inter-annual hydrological variability. Exported nutrient load increased in the downstream direction and coincided with decreased in-stream nutrient removal, probably worsened by the significant chemical and geomorphological impairment found in the lower parts of the watershed. PMID:23031293

  14. Response of Riparian Vegetation in Australia's Largest River Basin to Inter and Intra-Annual Climate Variability and Flooding as Quantified with Landsat and MODIS

    NASA Astrophysics Data System (ADS)

    Broich, M.; Tulbure, M. G.

    2015-12-01

    Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB), an area that covers over 1M km^2, as a case study. The MDB is the country's primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999-2009). Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the sub- continental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images), Bureau of Meteorology data and one decade of MODIS data. Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a 'boom' and 'bust' cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and Okavango River delta in Africa or

  15. Response of Riparian Vegetation in AUSTRALIA"S Largest River Basin to Inter and Intra-Annual Climate Variability and Flooding as Quantified with Landsat and Modis

    NASA Astrophysics Data System (ADS)

    Broich, M.; Tulbure, M. G.

    2016-06-01

    Australia is a continent subject to high rainfall variability, which has major influences on runoff and vegetation dynamics. However, the resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified in a spatially explicit way. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB), an area that covers over 1M km2, as a case study. The MDB is the country's primary agricultural area with scarce water resources subject to competing demands and impacted by climate change and more recently by the Millennium Drought (1999-2009). Riparian vegetation in the MDB floodplain suffered extensive decline providing a dramatic degradation of riparian vegetation. We quantified the spatial-temporal impact of rainfall, temperature and flooding patters on vegetation dynamics at the subcontinental to local scales and across inter to intra-annual time scales based on three decades of Landsat (25k images), Bureau of Meteorology data and one decade of MODIS data. Vegetation response varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Vegetation degradation trends were observed over riparian forests and woodlands in areas where flooding regimes have changed to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a `boom' and `bust' cycle, related to inter-annual rainfall variability. Spatial patters of vegetation degradation changed along the N-S rainfall gradient but flooding regimes and vegetation degradation patterns also varied at finer scale, highlighting the importance of a spatially explicit, internally consistent analysis and setting the stage for investigating further cross-scale relationships. Results are of interest for land and water management decisions. The approach developed here can be applied to other areas globally such as the Nile river basin and Okavango River delta in Africa or the

  16. Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

    NASA Astrophysics Data System (ADS)

    Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

    2014-12-01

    Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2

  17. Inter-Annual Variability of Atmospheric Water Vapor as seen from the TOVS Pathfinder Path a Data Set

    NASA Technical Reports Server (NTRS)

    Mehta, Amita; Susskind, Joel

    1999-01-01

    The atmospheric water vapor is a major greenhouse gas and plays a critical role in determining energy and water cycle in the climate system. A new, global, long-term (1985-98) water vapor data set derived from the TIROS Operational Vertical Sounder (TOVS) Path A system will be introduced in the presentation. An assessment of the accuracy of the TOVS Path A water vapor data will he presented. The focus of this oral presentation will be on the inter-annual variability of the water vapor distribution in the atmosphere. Also, water vapor distribution observed during 1997/98 ENSO event will be shown.

  18. Temperature drives inter-annual variability of growing season CO2 and CH4 fluxes of Siberian lowland tundra

    NASA Astrophysics Data System (ADS)

    Kutzbach, Lars; Wille, Christian; Runkle, Benjamin; Schreiber, Peter; Sachs, Torsten; Langer, Moritz; Boike, Julia; Pfeiffer, Eva-Maria

    2015-04-01

    Due to the logistic and technical difficulties associated with experimental work in high latitudes, long-term measurements of CO2 and CH4 fluxes from arctic ecosystems are still rare, and published trace gas balances often rely on measurements from one or few growing seasons. The inter-annual variability of environmental conditions such as temperature, precipitation, snow cover, and timing of snow melt can be high in the Arctic, especially for regions which are influenced by both continental and maritime climates, such as the Siberian arctic lowlands. For these ecosystems, we must also expect a great inter-annual variability in the balance of trace gases. Multi-annual data sets are needed to investigate this variability and its drivers. Here we present multi-annual late summer CO2 and CH4 flux data from the Lena River Delta in the Siberian Arctic (72° N, 126° E). The study site Samoylov Island is characterized by polygonal lowland tundra, a vegetation dominated by mosses and sedges, a soil complex of Glacic, Turbic and Histic Cryosols, and an active layer depth of on average 0.5 m. Seasonal flux measurements were carried out with the eddy covariance technique during the 13-year period 2002 - 2014. Within this period, CO2 flux data overlaps during 37 days (20 July - 25 August) for 12 years, and CH4 flux data overlaps during 25 days (28 July - 21 August) for 9 years. Cumulative net ecosystem CO2 exchange (NEE) during the late summer overlap period is fairly consistent for 9 out of 12 years with a CO2 uptake of 1.9 ± 0.1 mol m-2. Three years show a clearly smaller uptake of

  19. Seasonal and Inter-annual Variation in Wood Production in Tropical Trees on Barro Colorado Island, Panama, is Related to Local Climate and Species Functional Traits

    NASA Astrophysics Data System (ADS)

    Cushman, K.; Muller-Landau, H. C.; Kellner, J. R.; Wright, S. J.; Condit, R.; Detto, M.; Tribble, C. M.

    2015-12-01

    Tropical forest carbon budgets play a major role in global carbon dynamics, but the responses of tropical forests to current and future inter-annual climatic variation remains highly uncertain. Better predictions of future tropical forest carbon fluxes require an improved understanding of how different species of tropical trees respond to changes in climate at seasonal and inter-annual temporal scales. We installed dendrometer bands on a size-stratified sample of 2000 trees in old growth forest on Barro Colorado Island, Panama, a moist lowland forest that experiences an annual dry season of approximately four months. Tree diameters were measured at the beginning and end of the rainy season since 2008. Additionally, we recorded the canopy illumination level, canopy intactness, and liana coverage of all trees during each census. We used linear mixed-effects models to evaluate how tree growth was related to seasonal and interannual variation in local climate, tree condition, and species identity, and how species identity effects related to tree functional traits. Climatic variables considered included precipitation, solar radiation, soil moisture, and climatological water deficit, and were all calculated from high-quality on-site measurements. Functional traits considered included wood density, maximum adult stature, deciduousness, and drought tolerance. We found that annual wood production was positively related to water availability, with higher growth in wetter years. Species varied in their response to seasonal water availability, with some species showing more pronounced reduction of growth during the dry season when water availability is limited. Interspecific variation in seasonal and interannual growth patterns was related to life-history strategies and species functional traits. The finding of higher growth in wetter years is consistent with previous tree ring studies conducted on a small subset of species with reliable annual rings. Together with previous

  20. Inter-annual variability of exchange processes at the outer Black Sea shelf

    NASA Astrophysics Data System (ADS)

    Shapiro, Georgy; Wobus, Fred; Yuan, Dongliang; Wang, Zheng

    2014-05-01

    zsoy, 1997. The Black Sea Cold Intermediate Layer, in: Özsoy, E. and A. Mikaelyan (editors), Sensitivity to Change: Black Sea, Baltic Sea and North Sea, NATO ASI Series (Partnership Sub-series, Environment, 27), Kluwer Academic Publishers, Dordrecht, 536 pp. Shapiro, G.I., F. Wobus, D.L. Aleynik, 2011. Seasonal and inter-annual temperature variability in the bottom waters over the western Black Sea shelf, Ocean Science 7, 585-596. Shapiro, G., Luneva, M., Pickering, J., and Storkey, D., 2013. The effect of various vertical discretization schemes and horizontal diffusion parameterization on the performance of a 3-D ocean model: the Black Sea case study, Ocean Science, 9, 377-390. Staneva, J. V. and E. V. Stanev, 1997. Cold water mass formation in the Black Sea. Analysis on numerical model simulations. In: E. Ozsoy and A. Mikaelyan (eds.), Sensitivity to change: Black Sea, Baltic Sea and North Sea. NATO ASI Series, Vol. 27, Kluwer Academic Publishers, 375-393.

  1. Inter-annual changes in detritus-based food chains can enhance plant growth response to elevated atmospheric CO2.

    PubMed

    Hines, Jes; Eisenhauer, Nico; Drake, Bert G

    2015-12-01

    Elevated atmospheric CO2 generally enhances plant growth, but the magnitude of the effects depend, in part, on nutrient availability and plant photosynthetic pathway. Due to their pivotal role in nutrient cycling, changes in abundance of detritivores could influence the effects of elevated atmospheric CO2 on essential ecosystem processes, such as decomposition and primary production. We conducted a field survey and a microcosm experiment to test the influence of changes in detritus-based food chains on litter mass loss and plant growth response to elevated atmospheric CO2 using two wetland plants: a C3 sedge (Scirpus olneyi) and a C4 grass (Spartina patens). Our field study revealed that organism's sensitivity to climate increased with trophic level resulting in strong inter-annual variation in detritus-based food chain length. Our microcosm experiment demonstrated that increased detritivore abundance could not only enhance decomposition rates, but also enhance plant growth of S. olneyi in elevated atmospheric CO2 conditions. In contrast, we found no evidence that changes in the detritus-based food chains influenced the growth of S. patens. Considered together, these results emphasize the importance of approaches that unite traditionally subdivided food web compartments and plant physiological processes to understand inter-annual variation in plant production response to elevated atmospheric CO2. PMID:25953075

  2. A modelling study of inter-annual variation of Kuroshio intrusion on the shelf of East China Sea

    NASA Astrophysics Data System (ADS)

    Li, Jiaxing; Wei, Hao; Zhang, Zhihua; Lu, Youyu

    2013-12-01

    Inter-annual variability of the Kuroshio water intrusion on the shelf of East China Sea (ECS) was simulated with a nested global and Northwest Pacific ocean circulation model. The model analysis reveals the influence of the variability of Kuroshio transport east of Taiwan on the intrusion to the northeast of Taiwan: high correlation ( r = 0.92) with the on-shore volume flux in the lower layer (50-200 m); low correlation ( r = 0.50) with the on-shore flux in the upper layer (0-50 m). Spatial distribution of correlations between volume fluxes and sea surface height suggests that inter-annual variability of the Kuroshio flux east of Taiwan and its subsurface water intruding to the shelf lag behind the sea surface height anomalies in the central Pacific at 162°E by about 14 months, and could be related to wind-forced variation in the interior North Pacific that propagates westward as Rossby waves. The intrusion of Kuroshio surface water is also influenced by local winds. The intruding Kuroshio subsurface water causes variations of temperature and salinity of bottom waters on the southern ECS shelf. The influence of the intruding Kuroshio subsurface water extends widely from the shelf slope northeast of Taiwan northward to the central ECS near the 60 m isobath, and northeastward to the region near the 90 m isobath.

  3. Inter-Sentential Patterns of Code-Switching: A Gender-Based Investigation of Male and Female EFL Teachers

    ERIC Educational Resources Information Center

    Gulzar, Malik Ajmal; Farooq, Muhammad Umar; Umer, Muhammad

    2013-01-01

    This article has sought to contribute to discussions concerning the value of inter-sentential patterns of code-switching (henceforth ISPCS) particularly in the context of EFL classrooms. Through a detailed analysis of recorded data produced in that context, distinctive features in the discourse were discerned which were associated with males' and…

  4. Space-time variability of Indonesian rainfall at inter-annual and multi-decadal time scales

    NASA Astrophysics Data System (ADS)

    Yanto; Rajagopalan, Balaji; Zagona, Edith

    2016-01-01

    We investigated the space-time variability of wet (Nov-Apr) and dry (May-Oct) season rainfall over Indonesia, using monthly gridded rainfall data from the University of East Angela Climatic Research Unit covering the period 1901-2012. Three complimentary techniques were employed—(1) principal component analysis to identify the dominant modes of variability, (2) wavelet spectral analysis to identify the spectral characteristics of the leading modes and their coherence with large scale climate variables and (3) Bayesian Dynamical Linear Model (BDLM) to quantify the temporal variability of the association between rainfall modes and climate variables. In the dry season when the Inter Tropical Convergence Zone (ITCZ) is to the north of the equator the leading two principal components (PCs) explain close to 50 % of the rainfall. In the wet season the ITCZ moves to the south and the leading PCs explain close to 30 % of the variance. El Niño Southern Oscillation (ENSO) is the driver of the leading modes of rainfall variability during both seasons. We find asymmetry in the teleconnections of ENSO to high and low rainfall years in the dry season. Furthermore, ENSO and the leading PCs of rainfall have spectral coherence in the inter-annual band (2-8 years) over the entire period of record and in the multi-decadal (8-16 years) band in post-1980 years. In addition, during the 1950-1980 period the second mode of variability in both seasons has a strong relationship with Pacific Decadal Oscillation. The association between ENSO and the leading mode of Indonesian rainfall has strengthened in recent decades, more so during dry season. These inter-annual and multi-decadal variability of Indonesian rainfall modulated by Pacific climate drivers has implications for rainfall and hydrologic predictability important for water resources management.

  5. From seasonal to decadal inter-annual variability of mesozooplankton biomass in the Northern Adriatic Sea (Gulf of Trieste)

    NASA Astrophysics Data System (ADS)

    Kamburska, Lyudmila; Fonda-Umani, Serena

    2009-11-01

    This paper reports the rate of change of mesozooplankton biomass on seasonal, inter-annual and decadal time scale in the Gulf of Trieste (NE Mediterranean, Northern Adriatic). We measured variability in mesozooplankton dry weight (mg DW m - 3 ), organic carbon and nitrogen contents of the DW in relation to mesozooplankton taxonomic structure and some environmental parameters. The study is based on data obtained from mesozooplankton samples collected monthly by a vertical WP2 net (200 µm) from January 1986 to September 2005 at one monitoring station, a coastal site in the Gulf of Trieste. We considered mesozooplankton DW in relation to copepods, phytoplankton taxonomic structure, water temperature and North Atlantic Oscillation. For further analyses we counted also on data for DW for the period 1972-1980, monthly data for organic carbon (mg C m - 3 ) and nitrogen contents (mg N m - 3 ) of the DW for the period 1991-2005, determined by a CHN Elemental Analyzer. We explored statistically our high temporal resolution time series data picking out the main features: seasonal components and trends. Mesozooplankton DW ranged from only 1 mg m - 3 (January 1977) to 95 mg m - 3 (March 1990) in the coastal ecosystem of the Northern Adriatic during the period 1972-2005. The annual cycle of the DW was found to be bimodal with maximum in late winter-spring and a weaker one in late summer. Maximum DW were regularly recorded when Copepods prevailed the mesozooplankton community structure. Similarly, high organic carbon and nitrogen contents were detected when copepods dominated, although wide-ranging on a seasonal scale. Irregular intra- and inter-annual fluctuations were typical mostly during the 1990s. Mesozooplankton DW sharply shifted since 2001-2002 to the level exceeding the observed one during the regime of the 1980s. Our results indicate substantial changes in the seasonal timing of mesozooplankton DW, which together with decadal inter-annual fluctuations match

  6. Inter-annual variation in the response of leaf-out onset to soil moisture increase in a teak plantation in northern Thailand.

    PubMed

    Yoshifuji, Natsuko; Igarashi, Yasunori; Tanaka, Nobuaki; Tanaka, Katsunori; Sato, Takanori; Tantasirin, Chatchai; Suzuki, Masakazu

    2014-11-01

    To understand the impact of inter-annual climate change on vegetation-atmosphere mass and energy exchanges, it has become necessary to explore changes in leaf-out onset in response to climatic fluctuations. We examined the response of leaf-out and transpiration onset dates to soil moisture in a teak plantation in northern Thailand based on a 12-year leaf area index and sap flow measurements. The date of leaf-out and transpiration onset varied between years by up to 40 days, and depended on the initial date when the relative extractable water in a soil layer of 0-0.6 m (Θ) was greater than 0.2 being consistent with our previous results. Our new finding is that the delay in leaf-out and transpiration onset relative to the initial date when Θ > 0.2 increases linearly as the initial date on which Θ > 0.2 becomes earlier. The delay spans about 20 days in years when Θ > 0.2 occurs in March (the late dry season)-much earlier than usual because of heavy pre-monsoon rainfalls-while there is little delay in years when Θ > 0.2 occurs in May. This delay indicates the influence of additional factors on leaf-out onset, which controls the delay in the response of leaf-out to soil moisture increase. The results increased our knowledge about the pattern and extent of the changes in leaf phenology that occur in response to the inter-annual climate variation in tropical regions, where, in particular, such research is needed. PMID:24469544

  7. Inter-annual variation in the response of leaf-out onset to soil moisture increase in a teak plantation in northern Thailand

    NASA Astrophysics Data System (ADS)

    Yoshifuji, Natsuko; Igarashi, Yasunori; Tanaka, Nobuaki; Tanaka, Katsunori; Sato, Takanori; Tantasirin, Chatchai; Suzuki, Masakazu

    2014-01-01

    To understand the impact of inter-annual climate change on vegetation-atmosphere mass and energy exchanges, it has become necessary to explore changes in leaf-out onset in response to climatic fluctuations. We examined the response of leaf-out and transpiration onset dates to soil moisture in a teak plantation in northern Thailand based on a 12-year leaf area index and sap flow measurements. The date of leaf-out and transpiration onset varied between years by up to 40 days, and depended on the initial date when the relative extractable water in a soil layer of 0-0.6 m (Θ) was greater than 0.2 being consistent with our previous results. Our new finding is that the delay in leaf-out and transpiration onset relative to the initial date when Θ > 0.2 increases linearly as the initial date on which Θ > 0.2 becomes earlier. The delay spans about 20 days in years when Θ > 0.2 occurs in March (the late dry season)—much earlier than usual because of heavy pre-monsoon rainfalls—while there is little delay in years when Θ > 0.2 occurs in May. This delay indicates the influence of additional factors on leaf-out onset, which controls the delay in the response of leaf-out to soil moisture increase. The results increased our knowledge about the pattern and extent of the changes in leaf phenology that occur in response to the inter-annual climate variation in tropical regions, where, in particular, such research is needed.

  8. Low Spatial and Inter-Annual Variability in Evaporation from an Intensively Grazed Temperate Pasture System in New Zealand

    NASA Astrophysics Data System (ADS)

    Pronger, J.; Campbell, D.; Clearwater, M.; Rutledge, S.; Wall, A.; Schipper, L. A.

    2015-12-01

    Ecosystem scale measurements of evaporation (E) from intensively managed pasture systems are scarce and are important for informing water resource decision making, drought forecasting, and validation of Earth system models and remote sensing. We measured E from intensively grazed, unirrigated, ryegrass and clover pasture in New Zealand using eddy covariance (EC) for three years (2012 - 2014). Spatial variation in E was less than 3% during the initial study period when up to three sites were operating simultaneously. Inter-annual variability was also less than 3% over the three consecutive years (710 - 730 mm) at one site. The absence of spatial and inter-annul variation largely occurred because E was strongly controlled by net radiation (daytime half-hourly data r2 = 0.83, p < 0.01) which was relatively consistent between sites and years. However, soil moisture decreased surface conductance during seasonal drought constraining E relative to net radiation. Variation in drought severity between years caused variation in seasonal E between years, for example, a relatively severe autumn drought in 2013 reduced E over autumn by 13% compared to 2012. Coincidentally, two unusually large spring and early summer rainfall events during warm conditions later in 2013 increased summer E by 12% compared to 2012 and therefore similar annual totals were measured between years. The FAO56 Penman-Monteith model was able to accurately predict daily E over an annual cycle (r2 = 0.81) to within 5 % of measured cumulative E with a crop factor of 0.96 (determined under non water-limiting conditions) and a water stress coefficient to account for soil moisture restrictions. Intensive grazing events, that remove a large fraction of standing pasture biomass, were found to have no effect on evaporation. The absence of a grazing effect suggests that leaf area was not an important control of E, likely because increases in soil E were able to compensate for decreased transpiration.

  9. Trends in intra- and inter-annual temperature variabilities across Sudan.

    PubMed

    Elagib, Nadir Ahmed

    2010-01-01

    Four mean temperature variables, namely maximum (MAX), minimum (MIN), mean (MEAN) and diurnal temperature range (DTR), were considered for 14 selected observational stations throughout Sudan. The objectives were to investigate the seasonal and annual regimes, the seasonal and annual trends, the intra-annual variability (IAV) by the coefficient of variation (CV), and the interrelationships between the temperature variables and percent of possible sunshine. A mounting evidence of daytime and nighttime warming since the 1940s until 2005 is presented. The exception is the dry season which is dominated by daytime cooling attributable to the damping effect of dust haze/storms. Apparently, the progressive drought across inland locations has raised the MAXs, and to a lesser extent the MINs, of the wet season over those for the hot season. Accordingly, maximum rates of 0.451 and 0.336 degrees C decade(-1) were found for the nighttime and daytime temperatures, respectively. The extreme eastern and western locations have been frequently dominated by the warmest trend rates obtained nationwide. The prevalence of significant decreases (increases) of DTR is more apparent in the dry, hot and annual series (wet series). Depending on the temperature variable under consideration, many stations possessed significant trends toward either increased or decreased variability of the within-year monthly values, i.e. IAV. The correlation between the time series of annual CV and extreme values for each of the four temperature variables shows generally that warmer climate in Sudan is associated with higher intra-annual temperature variability and vise versa, i.e. the CV is directly correlated with the highest value within the year, but inversely correlated with the lowest one. The findings of this investigation also indicate that the DTR is directly related to percent of possible sunshine, but the relationship of the latter parameter is not so clear with MAX, MIN and MEAN. PMID:21053725

  10. Uncovering Patterns of Inter-Urban Trip and Spatial Interaction from Social Media Check-In Data

    PubMed Central

    Liu, Yu; Sui, Zhengwei; Kang, Chaogui; Gao, Yong

    2014-01-01

    The article revisits spatial interaction and distance decay from the perspective of human mobility patterns and spatially-embedded networks based on an empirical data set. We extract nationwide inter-urban movements in China from a check-in data set that covers half a million individuals within 370 cities to analyze the underlying patterns of trips and spatial interactions. By fitting the gravity model, we find that the observed spatial interactions are governed by a power law distance decay effect. The obtained gravity model also closely reproduces the exponential trip displacement distribution. The movement of an individual, however, may not obey the same distance decay effect, leading to an ecological fallacy. We also construct a spatial network where the edge weights denote the interaction strengths. The communities detected from the network are spatially cohesive and roughly consistent with province boundaries. We attribute this pattern to different distance decay parameters between intra-province and inter-province trips. PMID:24465849

  11. Evaluating the Relative Magnitude of Intra- and Inter-annual Metric Variability

    NASA Astrophysics Data System (ADS)

    Carter, J. L.; Fend, S. V.; Weissich, P.

    2005-05-01

    Understanding the magnitude of both short- and long-term temporal variability in metrics derived from lotic macroinvertebrate assemblages is important for both the design and analysis of water quality assessments. Sampling on an annual or even longer interval is common in programs that assess many sites over large geographic areas. These sampling regimes often lead sampling periods that extend over several months. Extended sampling periods can potentially influence the assessment because of phenological change in the benthic assemblage. To address the question of the effects of short- and long-term variability in common metrics, we collected benthic invertebrates every two weeks for a year from 6 sites. Within-site samples were grouped into 2 month intervals. We also collected annually from 9 sites for a period of 4 years. In general, the range of variation in metrics was similar regardless of temporal scale evaluated. For example, within-site, within-group % mayflies had coefficient of variations that ranged from 6 to 104 and within-site, among-year annual variability ranged from 9 to 111. The similarity in the ranges indicates that short-term temporal variability has the potential to confound the interpretation of long-term variability when evaluating annual or greater changes in benthic assemblage structure.

  12. Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

    NASA Astrophysics Data System (ADS)

    Zhang, Jianbao; Ma, Zhongjun; Chen, Guanrong

    2014-06-01

    All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding or deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.

  13. Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

    SciTech Connect

    Zhang, Jianbao; Ma, Zhongjun; Chen, Guanrong

    2014-06-15

    All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding or deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.

  14. CO2 fluxes at northern fens and bogs have opposite responses to inter-annual fluctuations in water table

    NASA Astrophysics Data System (ADS)

    Sulman, Benjamin N.; Desai, Ankur R.; Saliendra, Nicanor Z.; Lafleur, Peter M.; Flanagan, Lawrence B.; Sonnentag, Oliver; Mackay, D. Scott; Barr, Alan G.; van der Kamp, Garth

    2010-10-01

    This study compares eddy-covariance measurements of carbon dioxide fluxes at six northern temperate and boreal peatland sites in Canada and the northern United States of America, representing both bogs and fens. The two peatland types had opposite responses of gross ecosystem photosynthesis (GEP) and ecosystem respiration (ER) to inter-annual fluctuations in water table level. At fens, wetter conditions were correlated with lower GEP and ER, while at bogs wetter conditions were correlated with higher GEP and ER. We hypothesize that these contrasting responses are due to differences in the relative contributions of vascular plants and mosses. The coherence of our results between sites representing a range of average environmental conditions indicates ecosystem-scale differences in resilience to hydrological changes that should be taken into account when considering the future of peatland ecosystem services such as carbon sequestration under changing environmental conditions.

  15. Using Decision Trees to Examine Relationships between Inter-Annual Vegetation Variability, Topographic Attributes, and Climate Signals

    NASA Astrophysics Data System (ADS)

    White, A. B.; Kumar, P.

    2003-12-01

    The objective of this research is to develop KDD (knowledge discovery in databases) techniques for spatio-temporal geo-data, and use these techniques to examine inter-annual vegetation health signals. The underlying hypothesis of the research is that the signatures of inter-annual variability of climate on vegetation dynamics as represented by the statistical descriptors of vegetation index variations depend upon a variety of attributes related to the topography, hydrology, physiography, and climate. NDVI (normalized differential vegetation index) is enlisted to represent vegetation health and relationships between this index and topographic attributes such as elevation, slope, aspect, compound topographic index (CTI), and the proximity to a stream, are analyzed. Several scientific questions related to the identification and characterization of the inter-annual variability ensue as a consequence of our hypothesis. Investigations were performed using 13 years of 1-km resolution NDVI data from the AVHRR instrument on NOAA's POES (polar-orbiting operational environmental satellite) over the continental U.S. Various temporal change indices were used in order to identify anomalous inter-annual behavior in the NDVI index, including maximum absolute and relative deviations from the 13-year mean and positive and negative persistence indices (after Zhou et al., 2001). The KDD technique used in this research is the decision tree, which falls under the classification and prediction division of data mining techniques. The algorithm is similar to c4.5 and id3, but can handle continuous input and output values without binning and is optimized to determine the minimum error. Future work will incorporate clustering algorithms (both distance and density-based) and association rule algorithms (constraint-based) adapted for spatial-temporal data. Investigations will also be performed at smaller spatial scales, integrating higher resolution data. Throughout the growing season

  16. Spatial and inter-annual variability of the macrobenthic communities within a coastal lagoon (Óbidos lagoon) and its relationship with environmental parameters

    NASA Astrophysics Data System (ADS)

    Carvalho, Susana; Moura, Ana; Gaspar, Miguel B.; Pereira, Paula; Cancela da Fonseca, Luís; Falcão, Manuela; Drago, Teresa; Leitão, Francisco; Regala, João

    2005-05-01

    The present work aims to analyse spatial and inter-annual variability in the benthic environment within the Óbidos lagoon, assessing the relationships between environmental characteristics and macrobenthic distribution patterns. Sediment samples were collected in February 2001 and 2002 for the study of macrofauna and biogeochemical parameters (sediment grain size, organic matter, organic carbon, chlorophyll a, and phaeopigments). Comparing 2001 to 2002, a general increase in the number of species, diversity and equitability indices was observed throughout the study area. Likewise, there was an increase of phytopigments and organic matter contents in the upper sediment layer. Based on the macrobenthic community patterns and environmental variables three main areas could be distinguished in both years: an outer area near the inlet mostly influenced by the sea, with very depressed number of species and abundance, and dominated by Saccocirrus papillocercus, Lekanesphaera levii, Microphthalmus similis and Nephtys cirrosa; an intermediate area located in the central part of the lagoon characterized by sandy sediment and low organic carbon, and colonized by a high diverse community with Hydrobia ulvae, Cerastoderma edule and Abra ovata as the most characteristic species; and the innermost area of the lagoon with muddy enriched sediments dominated by Heteromastus filiformis, oligochaetes, Scrobicularia plana, Cyathura carinata, Corophium acherusicum, phoronids, insect larvae and Corbula gibba. Deposit-feeders were dominant in the muddy sediments from the inner area, where suspension-feeders were also abundant. Carnivores were associated with clean sandy sediments from the inlet area and herbivores were more abundant within the central area.

  17. Inter-annual variation in American redstart (Setophaga ruticilla) plumage colour is associated with rainfall and temperature during moult: an 11-year study.

    PubMed

    Reudink, Matthew W; McKellar, Ann E; Marini, Kristen L D; McArthur, Sarah L; Marra, Peter P; Ratcliffe, Laurene M

    2015-05-01

    Carotenoid-based colouration plays an important role in sexual signaling in animals as an honest indicator of individual quality during mate choice and competitive interactions. However, few studies have examined how natural variation in weather conditions influences inter-annual variation in the expression of ornamentation, potentially through affecting the dietary availability of carotenoids. In this study, we examine variation in the expression of carotenoid-based plumage colouration in relation to temperature and rainfall during the pre-moulting and moulting period over 11 years in a population of American redstarts, Setophaga ruticilla, breeding in eastern Canada. We used reflectance spectrometry of tail feathers collected from male and female redstarts to relate feather colour with weather conditions the previous breeding season during the months over which redstarts are likely to moult (June-September). At a population level, birds expressed feathers with higher red chroma and lower brightness in years following high July rainfall and low August temperature. The pattern was stronger in males, but was generally consistent across ages and sexes. Analyses of feathers from repeatedly captured birds indicated that the above patterns could be explained by individual change in feather colour. We suggest that higher rainfall during the moulting period may increase insect abundance and the availability of dietary carotenoids. This is among the first studies to show effects of weather conditions on a sexual signalling trait, which may have important consequences for sexual selection, mate choice, and the reliability of putative signals. PMID:25433695

  18. Inter-rater reliability for movement pattern analysis (MPA): measuring patterning of behaviors versus discrete behavior counts as indicators of decision-making style

    PubMed Central

    Connors, Brenda L.; Rende, Richard; Colton, Timothy J.

    2014-01-01

    The unique yield of collecting observational data on human movement has received increasing attention in a number of domains, including the study of decision-making style. As such, interest has grown in the nuances of core methodological issues, including the best ways of assessing inter-rater reliability. In this paper we focus on one key topic – the distinction between establishing reliability for the patterning of behaviors as opposed to the computation of raw counts – and suggest that reliability for each be compared empirically rather than determined a priori. We illustrate by assessing inter-rater reliability for key outcome measures derived from movement pattern analysis (MPA), an observational methodology that records body movements as indicators of decision-making style with demonstrated predictive validity. While reliability ranged from moderate to good for raw counts of behaviors reflecting each of two Overall Factors generated within MPA (Assertion and Perspective), inter-rater reliability for patterning (proportional indicators of each factor) was significantly higher and excellent (ICC = 0.89). Furthermore, patterning, as compared to raw counts, provided better prediction of observable decision-making process assessed in the laboratory. These analyses support the utility of using an empirical approach to inform the consideration of measuring patterning versus discrete behavioral counts of behaviors when determining inter-rater reliability of observable behavior. They also speak to the substantial reliability that may be achieved via application of theoretically grounded observational systems such as MPA that reveal thinking and action motivations via visible movement patterns. PMID:24999336

  19. Effects of Climatic Factors and Ecosystem Responses on the Inter-Annual Variability of Evapotranspiration in a Coniferous Plantation in Subtropical China

    PubMed Central

    Xu, Mingjie; Wen, Xuefa; Wang, Huimin; Zhang, Wenjiang; Dai, Xiaoqin; Song, Jie; Wang, Yidong; Fu, Xiaoli; Liu, Yunfen; Sun, Xiaomin; Yu, Guirui

    2014-01-01

    Because evapotranspiration (ET) is the second largest component of the water cycle and a critical process in terrestrial ecosystems, understanding the inter-annual variability of ET is important in the context of global climate change. Eight years of continuous eddy covariance measurements (2003–2010) in a subtropical coniferous plantation were used to investigate the impacts of climatic factors and ecosystem responses on the inter-annual variability of ET. The mean and standard deviation of annual ET for 2003–2010 were 786.9 and 103.4 mm (with a coefficient of variation of 13.1%), respectively. The inter-annual variability of ET was largely created in three periods: March, May–June, and October, which are the transition periods between seasons. A set of look-up table approaches were used to separate the sources of inter-annual variability of ET. The annual ETs were calculated by assuming that (a) both the climate and ecosystem responses among years are variable (Vcli-eco), (b) the climate is variable but the ecosystem responses are constant (Vcli), and (c) the climate is constant but ecosystem responses are variable (Veco). The ETs that were calculated under the above assumptions suggested that the inter-annual variability of ET was dominated by ecosystem responses and that there was a negative interaction between the effects of climate and ecosystem responses. These results suggested that for long-term predictions of water and energy balance in global climate change projections, the ecosystem responses must be taken into account to better constrain the uncertainties associated with estimation. PMID:24465610

  20. Intra-seasonal and Inter-annual variability of Bowen Ratio over rain-shadow region of North peninsular India

    NASA Astrophysics Data System (ADS)

    Morwal, S. B.; Narkhedkar, S. G.; Padmakumari, B.; Maheskumar, R. S.; Deshpande, C. G.; Kulkarni, J. R.

    2016-02-01

    Intra-seasonal and inter-annual variability of Bowen Ratio (BR) have been studied over the rain-shadow region of north peninsular India during summer monsoon season. Daily grid point data of latent heat flux (LHF), sensible heat flux (SHF) from NCEP/NCAR Reanalysis for the period 1970-2014 have been used to compute daily area-mean BR. Daily grid point rainfall data at a resolution of 0.25° × 0.25° from APHRODITE's Water Resources for the available period 1970-2007 have been used to study the association between rainfall and BR. The study revealed that BR rapidly decreases from 4.1 to 0.29 in the month of June and then remains nearly constant at the same value (≤0.1) in the rest of the season. High values of BR in the first half of June are indicative of intense thermals and convective clouds with higher bases. Low values of BR from July to September period are indicative of weak thermals and convective clouds with lower bases. Intra-seasonal and inter-annual variability of BR is found to be inversely related to precipitation over the region. BR analysis indicates that the land surface characteristics of the study region during July-September are similar to that over oceanic regions as far as intensity of thermals and associated cloud microphysical properties are concerned. Similar variation of BR is found in El Nino and La Nina years. During June, an increasing trend is observed in SHF and BR and decreasing trend in LHF from 1976 to 2014. Increasing trend in the SHF is statistically significant.

  1. Inter-Annual Variability in Stream Water Temperature, Microclimate and Heat Exchanges: a Comparison of Forest and Moorland Environments

    NASA Astrophysics Data System (ADS)

    Garner, G.; Hannah, D. M.; Malcolm, I.; Sadler, J. P.

    2012-12-01

    Riparian forest is recognised as important for moderating stream temperature variability and has the potential to mitigate thermal extremes in a changing climate. Previous research on the heat exchanges controlling water column temperature has often been short-term or seasonally-constrained, with the few multi-year studies limited to a maximum of two years. This study advances previous work by providing a longer-term perspective which allows assessment of inter-annual variability in stream temperature, microclimate and heat exchange dynamics between a semi-natural woodland and a moorland (no trees) reach of the Girnock Burn, a tributary of the Scottish Dee. Automatic weather stations collected 15-minute data over seven consecutive years, which to our knowledge is a unique data set in providing the longest term perspective to date on stream temperature, microclimate and heat exchange processes. Results for spring-summer indicate that the presence of a riparian canopy has a consistent effect between years in reducing the magnitude and variability of mean daily water column temperature and daily net energy totals. Differences in the magnitude and variability in net energy fluxes between the study reaches were driven primarily by fluctuations in net radiation and latent heat fluxes in response to between- and within-year variability in growth of the riparian forest canopy at the forest and prevailing weather conditions at both the forest and moorland. This research provides new insights on the inter-annual variability of stream energy exchanges for moorland and forested reaches under a wide range of climatological and hydrological conditions. The findings therefore provide a more robust process basis for modelling the impact of changes in forest practice and climate change on river thermal dynamics.

  2. Evaluating Inter-Annual Climate Variability of Nitrogen Wet Deposition in the United States Using Wavelet Analysis

    NASA Astrophysics Data System (ADS)

    Nergui, T.; Thomas, N.; Liu, M.; Lamb, B. K.; Adam, J. C.; Chung, S. H.

    2012-12-01

    Human activities, primarily agricultural practices and fossil fuel combustion, have caused a significant increase in nitrogen (N) emissions into the atmosphere over the last 150 years. The increase in emission subsequently leads to elevated ozone concentration, haze, increased acid rain and N deposition at local and regional scales. Many ecosystems in the US are naturally N limited. These regions are highly vulnerable to increased N deposition which can lead to irreversible changes in biodiversity richness and composition of the ecosystems. Through the impact on atmospheric chemistry and scavenging by precipitation, climate variability can play a major role on N deposition rates. The El Niño/Southern Oscillation (ENSO), Northern Annular Mode/Arctic Oscillation (NAM/AO), North Atlantic Oscillation (NAO), and the Pacific-North American Pattern (PNA) indices are the key climate indices that characterize the climate in the contiguous US at inter-annual timescale. Here, we identify dominant periodic components (signal) in the N wet deposition and the climate index timeseries and examine their correlations and coherences using wavelet analysis. Seasonal precipitation and nitrogen (ammonium and nitrate) wet deposition data from the National Atmospheric Deposition Program (NADP), National Trends Network (NTN) for 87 sites across the United States are used for the study. The sites were selected based on data continuity of 21 years or more and NADP criteria for valid precipitation and wet deposition data. Precipitation data from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) are also used to replicate and validate the general features of climate variability effects in different regions of US. Initial analysis reveals nitrate wet deposition has a dominant 1-4 year periodicity while ammonium wet deposition has a shorter periodicity (about 0.5-2 year) during 1979 to 2011. Precipitation and total N wet deposition are most correlated in the Great Plains

  3. Inter-annual rainfall variations and suicide in New South Wales, Australia, 1964-2001

    NASA Astrophysics Data System (ADS)

    Nicholls, Neville; Butler, Colin D.; Hanigan, Ivan

    2006-01-01

    The suicide rate in New South Wales is shown to be related to annual precipitation, supporting a widespread and long-held assumption that drought in Australia increases the likelihood of suicide. The relationship, although statistically significant, is not especially strong and is confounded by strong, long-term variations in the suicide rate not related to precipitation variations. A decrease in precipitation of about 300 mm would lead to an increase in the suicide rate of approximately 8% of the long-term mean suicide rate.

  4. Functional patterns in an annual grassland during an AVIRIS overflight

    NASA Technical Reports Server (NTRS)

    Gamon, John A.; Field, Christopher B.; Roberts, Dar A.; Ustin, Susan L.; Valentini, Riccardo

    1993-01-01

    This study relates Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) imagery to ground measurements of vegetation distribution, physiology, and productivity at Stanford University's Jasper Ridge Biological Preserve. Primary efforts focused on a 9-ha region of annual grassland where we completed a detailed ground-based study in conjunction with a 15 May 1991 AVIRIS overflight. Spectral mixture analysis and the normalized difference vegetation index (NDVI) calculated from AVIRIS data were used to evaluate spatial patterns of vegetation type, productivity, and potential physiological activity. Concurrent ground sampling revealed a high degree of correlation between NDVI and estimates of canopy chemistry, structure, productivity, and CO2 flux, supporting the use of imaging spectrometry to estimate spatial and temporal trends in vegetation physiology and productivity in this relatively simple grassland ecosystem. Geostatistical analyses of both ground and AVIRIS data supported the conclusion that the AVIRIS pixel size was suitable for describing the influence of major landscape features in this grassland and that spatial detail would be lost at slightly larger pixel sizes typical of other imaging spectrometers.

  5. Effect of inter-annual variability in pasture growth and irrigation response on farm productivity and profitability based on biophysical and farm systems modelling.

    PubMed

    Vogeler, Iris; Mackay, Alec; Vibart, Ronaldo; Rendel, John; Beautrais, Josef; Dennis, Samuel

    2016-09-15

    Farm system and nutrient budget models are increasingly being used in analysis to inform on farm decision making and evaluate land use policy options at regional scales. These analyses are generally based on the use of average annual pasture yields. In New Zealand (NZ), like in many countries, there is considerable inter-annual variation in pasture growth rates, due to climate. In this study a modelling approach was used to (i) include inter-annual variability as an integral part of the analysis and (ii) test the approach in an economic analysis of irrigation in a case study within the Hawkes Bay Region of New Zealand. The Agricultural Production Systems Simulator (APSIM) was used to generate pasture dry matter yields (DMY) for 20 different years and under both dryland and irrigation. The generated DMY were linked to outputs from farm-scale modelling for both Sheep and Beef Systems (Farmaxx Pro) and Dairy Systems (Farmax® Dairy Pro) to calculate farm production over 20 different years. Variation in DMY and associated livestock production due to inter-annual variation in climate was large, with a coefficient of variations up to 20%. Irrigation decreased this inter-annual variation. On average irrigation, with unlimited available water, increased income by $831 to 1195/ha, but when irrigation was limited to 250mm/ha/year income only increased by $525 to 883/ha. Using pasture responses in individual years to capturing the inter-annual variation, rather than the pasture response averaged over 20years resulted in lower financial benefits. In the case study income from irrigation based on an average year were 10 to >20% higher compared with those obtained from individual years. PMID:27203517

  6. Inter-Annual Variability of Fledgling Sex Ratio in King Penguins

    PubMed Central

    Viblanc, Vincent A.; Gachot-Neveu, Hélène; Beaugey, Magali; Le Maho, Yvon; Le Bohec, Céline

    2014-01-01

    As the number of breeding pairs depends on the adult sex ratio in a monogamous species with biparental care, investigating sex-ratio variability in natural populations is essential to understand population dynamics. Using 10 years of data (2000–2009) in a seasonally monogamous seabird, the king penguin (Aptenodytes patagonicus), we investigated the annual sex ratio at fledging, and the potential environmental causes for its variation. Over more than 4000 birds, the annual sex ratio at fledging was highly variable (ranging from 44.4% to 58.3% of males), and on average slightly biased towards males (51.6%). Yearly variation in sex-ratio bias was neither related to density within the colony, nor to global or local oceanographic conditions known to affect both the productivity and accessibility of penguin foraging areas. However, rising sea surface temperature coincided with an increase in fledging sex-ratio variability. Fledging sex ratio was also correlated with difference in body condition between male and female fledglings. When more males were produced in a given year, their body condition was higher (and reciprocally), suggesting that parents might adopt a sex-biased allocation strategy depending on yearly environmental conditions and/or that the effect of environmental parameters on chick condition and survival may be sex-dependent. The initial bias in sex ratio observed at the juvenile stage tended to return to 1∶1 equilibrium upon first breeding attempts, as would be expected from Fisher’s classic theory of offspring sex-ratio variation. PMID:25493708

  7. Inter-annual variations of methane emission from an open fen on the Qinghai-Tibetan Plateau: a three-year study.

    PubMed

    Chen, Huai; Wu, Ning; Wang, Yanfen; Zhu, Dan; Zhu, Qiu'an; Yang, Gang; Gao, Yongheng; Fang, Xiuqin; Wang, Xu; Peng, Changhui

    2013-01-01

    The study aimed to understand the inter-annual variations of methane (CH(4)) emissions from an open fen on the Qinghai-Tibetan Plateau (QTP) from 2005 to 2007. The weighted mean CH(4) emission rate was 8.37±11.32 mg CH(4) m(-2 )h(-1) during the summers from 2005 to 2007, falling in the range of CH(4) fluxes reported by other studies, with significant inter-annual and spatial variations. The CH(4) emissions of the year of 2006 (2.11±3.48 mg CH(4) m(-2 )h(-1)) were 82% lower than the mean value of the years 2005 and 2007 (13.91±17.80 mg CH(4) m(-2 )h(-1) and 9.44±14.32 mg CH(4) m(-2 )h(-1), respectively), responding to the inter-annual changes of standing water depths during the growing season of the three years. Significant drawdown of standing water depth is believed to cause such significant reduction in CH(4) emissions from wetlands in the year 2006, probably through changing the methanogen composition and decreasing its community size as well as activating methanotrophs to enhance CH(4) oxidation. Our results are helpful to understand the inter-annual variations of CH(4) emission and provide a more reasonable regional budget of CH(4) emission from wetlands on the QTP and even for world-wide natural wetlands under climate change. PMID:23342029

  8. Seasonal and inter-annual variability in rangeland NEE: Contributions of climatic anomalies and fluctuations in daytime and night-time CO2 fluxes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Net ecosystem exchange of CO2 (NEE) of terrestrial ecosystems varies seasonally and inter-annually partly because of climatic variability. If we are to predict climate-driven variation in NEE, we must understand how climatic anomalies at different temporal scales influence NEE and its components, ...

  9. Inter-Annual and Shorter-Term Variability in Physical and Biological Characteristics Across Barrow Canyon in August - September 2005-2014

    NASA Astrophysics Data System (ADS)

    Ashjian, C. J.; Okkonen, S. R.; Campbell, R. G.; Alatalo, P.

    2014-12-01

    Late summer physical and biological conditions along a 37-km transect crossing Barrow Canyon have been described for the past ten years as part of an ongoing program, supported by multiple funding sources including the NSF AON, focusing on inter-annual variability and the formation of a bowhead whale feeding hotspot near Barrow. These repeated transects (at least two per year, separated in time by days-weeks) provide an opportunity to assess the inter-annual and shorter term (days-weeks) changes in hydrographic structure, ocean temperature, current velocity and transport, chlorophyll fluorescence, nutrients, and micro- and mesozooplankton community composition and abundance. Inter-annual variability in all properties was high and was associated with larger scale, meteorological forcing. Shorter-term variability could also be high but was strongly influenced by changes in local wind forcing. The sustained sampling at this location provided critical measures of inter-annual variability that should permit detection of longer-term trends that are associated with ongoing climate change.

  10. Inter-annual variation of persistent organic pollutants (POPS) in an Antarctic top predator Arctocephalus gazella.

    PubMed

    Brault, Emily K; Goebel, Michael E; Geisz, Heidi N; Canuel, Elizabeth A; Dickhut, Rebecca M

    2013-11-19

    Persistent organic pollutants (POPs), contaminants that may bioaccumulate in upper trophic level organisms, were detected in the milk of a top predator, the Antarctic fur seal (Arctocephalus gazella). Multiparous females had significantly lower concentrations of certain POPs (trans-nonachlor, p,p'-DDE, and several PCBs) in their milk than primiparous females, likely due to the annual lactational transfer of the POP burden from mother to pup. Furthermore, there were significant interannual differences in POP concentrations in multiparous females' milk from five breeding seasons between 2000 and 2011. Decreasing trends in concentrations of certain POPs over the recent decade coincide with declining global emissions, yet atmospheric concentrations in the Antarctic are not always consistent with global trends, suggesting that additional factors may contribute to temporal trends of POPs in fur seals. Climate shifts and corresponding availability of krill over the past decade were not consistent with trends observed in POP concentrations in fur seal milk, suggesting that climate may not be a key factor. Additional mechanisms, such as variability in the geographic ranges of individual seals during overwintering migrations are discussed and should be explored further. PMID:24138491

  11. Inter-annual variation of NDVI over Korea Peninsula using harmonic analysis

    NASA Astrophysics Data System (ADS)

    Kim, In-hwan; Han, Kyung-Soo; Pi, Kyoung-Jin; Park, Soo-Jae; Kim, Sang-Il

    2010-10-01

    Global warming and climatic changes due to human activities impact on marine and terrestrial ecosystems, which feedbacks to climate system. These negative feedbacks amplify or accelerate again global climate change. In particular, life cycle of vegetation sensitively vary according to global climate change. This study attempts to analyze quantitatively vegetation change in Korea peninsula using harmonic analysis. Satellite data was extracted from SPOT/VEGETATION S10 MVC (Maximum Value Composite) NDVI (Normalized Difference Vegetation Index) products during 10 years (1999 to 2008) around Korea peninsula. This NDVI data set was pre-processed to correct noise pixels cause by cloud and ground wetness. Variation of vegetation life cycle was analyzed through amplitudes and phases of annual harmonic components (first harmonic components) per year for two land cover types (cropland and forest). The results clearly show that the peak of vegetation life cycle in Korea peninsula is brought forward to early. Especially, it represents that the phases over low latitudes area between 32.8°N and 38°N steadily decrease every year both forest and cropland. The study estimated that phase values moved up approximately 0.5 day per year in cropland and 0.8 day per year in forest.

  12. Searching for trends in inter-annual runoff records via a fractal geometric approach

    NASA Astrophysics Data System (ADS)

    Puente, C. E.; Maskey, M. L.; Cortis, A.; Sivakumar, B.

    2013-12-01

    In an attempt to model the specific complexity of geophysical (hydrological) records --beyond some key statistical qualifiers--, in the past we have developed a deterministic geometric procedure: the fractal-multifractal (FM) method. Through a series of successive studies, we have shown that the FM procedure, and its variants, are capable of preserving, in addition to important statistics, the textures and fine details of individual data sets. Following up on such promising results, in this study, we apply the FM approach to twenty years of daily runoff time series gathered in the Sacramento River at Freeport, in order to assess if the FM approach may elucidate the dynamics of the process. After removal of base flow, encodings of normalized annual data sets, integrating to one, yield alternative plausible parsimonious FM representations (i.e., more than one variant having a number of parameters that ranges from 8 to15) that faithfully describe all the twenty yearly runoff data sets studied, with maximum errors in accumulated runoff that are less than a mere 3% and compression ratios that range from 45:1 to 24:1. Starting a plausible search for hidden climate-change trends in the records, albeit from a short series, and studying the possibility of holistic predictions of runoff, one whole year at a time, we present a study of observed trends in FM parameters as a function of time.

  13. Serial correlation and inter-annual variability in relation to the statistical power of monitoring schemes to detect trends in fish populations.

    PubMed

    Nagelkerke, Leopold A J; van Densen, Wim L T

    2007-02-01

    We studied the effects of inter-annual variability and serial correlation on the statistical power of monitoring schemes to detect trends in biomass of bream (Abramis brama) in Lake Veluwemeer (The Netherlands). In order to distinguish between 'true' system variability and sampling variability we simulated the development of the bream population, using estimates for population structure and growth, and compared the resulting inter-annual variabilities and serial correlations with those from field data. In all cases the inter-annual variability in the field data was larger than in simulated data (e.g. for total biomass of all assessed bream sigma = 0.45 in field data, and sigma = 0.03-0.14 in simulated data) indicating that sampling variability decreased statistical power for detecting trends. Moreover, sampling variability obscured the inter-annual dependency (and thus the serial correlation) of biomass, which was expected because in this long-lived population biomass changes are buffered by the many year classes present. We did find the expected serial correlation in our simulation results and concluded that good survey data of long-lived fish populations should show low sampling variability and considerable inter-annual serial correlation. Since serial correlation decreases the power for detecting trends, this means that even when sampling variability would be greatly reduced, the number of sampling years to detect a change of 15%.year(-1) in bream populations (corresponding to a halving or doubling in a six-year period) would in most cases be more than six. This would imply that the six-year reporting periods that are required by the Water Framework Directive of the European Union are too short for the existing fish monitoring schemes. PMID:17219244

  14. Inter-annual dynamics of abyssal polychaete communities in the North East Pacific and North East Atlantic—A family-level study

    NASA Astrophysics Data System (ADS)

    Laguionie-Marchais, C.; Billett, D. S. M.; Paterson, G. L. D.; Ruhl, H. A.; Soto, E. H.; Smith, K. L., Jr.; Thatje, S.

    2013-05-01

    Characterising how deep-sea communities change on contemporary time-scales and understanding underlying ecosystem processes has become important under changing climate and the rise in the exploitation of deep-sea resources. However, little is known about these dynamics and processes. Long-term observations from which inter-annual variations can be detected are scarce in the deep sea. This study examines inter-annual changes in density, family richness and evenness, family and functional group rank abundance distributions of infaunal polychaetes at two abyssal stations in the North East Pacific (Station M, 1991 to 2005) and in the North East Atlantic (Porcupine Abyssal Plain, 1991 to 1999). The two long-term data sets were used to investigate not only if polychaete community structure and composition varied at inter-annual scales in terms of diversity and rank abundance distributions but also if any changes were related to previous observations in megafauna and environmental factors at each locality. The polychaete community structure at each locality was analysed using univariate statistics as well as multivariate ordination techniques based on Bray-Curtis similarity of the yearly family density. Sub-surface deposit feeders, such as Paraonidae, dominated the North East Pacific, whereas surface deposit feeders, such as Cirratulidae, dominated the North East Atlantic. Both stations showed inter-annual variations in density, family evenness and rank abundance distributions. The greatest changes occurred in 1998 in both time series when polychaete densities peaked, and switches in the rank abundance of the most abundant families and functional groups took place. Inter-annual variations in the polychaete community were correlated with a limited number of holothurian species changes, but no correlation was found with particulate organic matter flux or climate indices. Ecological and environmental factors behind the family-level changes remain elusive. Overall, changes in

  15. Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California

    NASA Astrophysics Data System (ADS)

    Campbell, Gregory S.; Thomas, Len; Whitaker, Katherine; Douglas, Annie B.; Calambokidis, John; Hildebrand, John A.

    2015-02-01

    Trends in cetacean density and distribution off southern California were assessed through visual line-transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004-November 2013. From sightings of the six most commonly encountered cetacean species, seasonal, annual and overall density estimates were calculated. Blue whales (Balaenoptera musculus), fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) were the most frequently sighted baleen whales with overall densities of 0.91/1000 km2 (CV=0.27), 2.73/1000 km2 (CV=0.19), and 1.17/1000 km2 (CV=0.21) respectively. Species specific density estimates, stratified by cruise, were analyzed using a generalized additive model to estimate long-term trends and correct for seasonal imbalances. Variances were estimated using a non-parametric bootstrap with one day of effort as the sampling unit. Blue whales were primarily observed during summer and fall while fin and humpback whales were observed year-round with peaks in density during summer and spring respectively. Short-beaked common dolphins (Delphinus delphis), Pacific white-sided dolphins (Lagenorhynchus obliquidens) and Dall's porpoise (Phocoenoidesdalli) were the most frequently encountered small cetaceans with overall densities of 705.83/1000 km2 (CV=0.22), 51.98/1000 km2 (CV=0.27), and 21.37/1000 km2 (CV=0.19) respectively. Seasonally, short-beaked common dolphins were most abundant in winter whereas Pacific white-sided dolphins and Dall's porpoise were most abundant during spring. There were no significant long-term changes in blue whale, fin whale, humpback whale, short-beaked common dolphin or Dall's porpoise densities while Pacific white-sided dolphins exhibited a significant decrease in density across the ten-year study. The results from this study were fundamentally consistent with earlier studies, but provide greater temporal and seasonal resolution.

  16. Inter-annual and decadal fluctuations of the Kuroshio in East China Sea and connection with wind and surface heat flux

    NASA Astrophysics Data System (ADS)

    Wang, J.; Oey, L. Y.

    2014-12-01

    Despite various attempts in the literature to link large scale oscillations of wind to long-term variations of the Kuroshio in East China Sea (ECS), the driving mechanism(s) are unknown. Here satellite altimetry data, wind, surface heat fluxes and sea-surface temperatures (SST) are used to analyze the fluctuations of Kuroshio path (KP) along the continental slope of ECS. The dominant EOF explains 44% of the variance, and its spatial pattern is of one sign, but with a concentrated amplitude some 160 km northeast of Taiwan. At the inter-annual periods, KP is found to be best correlated with the PTO index of Chang and Oey [2012, J.Clim], less so with PDO and a Kuroshio transport index, and is poorly correlated with other climate indices. The KP significantly correlates with a wind stress curl dipole along the Kuroshio, as well as with a zonal gradient in surface heat fluxnortheast of Taiwan [Oey et al 2010, Ocean Dyn], both of which are characteristics of the PTO, but not PDO. Over the past 2 decades, the KP has an onshore trend. The shelf's SST warms and cools in concert with the onshore and offshore paths of the Kuroshio, but the most prominent change occurs at a localized coastal zone immediately shoreward of the EOF's largest amplitude northeast of Taiwan.

  17. Inter- and intra-annual variability of vegetation in the northern hemisphere and its association with precursory meteorological factors

    NASA Astrophysics Data System (ADS)

    Myoung, Boksoon; Choi, Yong-Sang; Hong, Seungbum; Park, Seon Ki

    2013-01-01

    Determination of phenological variation is one of the most critical challenges in dynamic vegetation modeling, given the lack of a strong theoretical framework. Previous studies generally focused on the timing of a phenological event (e.g., bud-burst or onset of growing season) and its atmospheric prompts, but not on the interactive variations across phenological stages. This study, therefore, investigated the inter- and intra-annual variability existing in all the phenological stages and the relations of the variability with four meteorological variables (surface temperature (Ts), shortwave radiation (SW), vapor pressure deficit (VPD), and precipitation (PRCP)) using a 25-year (1982-2006) dataset of leaf area index (LAI) from the Advanced Very High Resolution Radiometer (AVHRR). Our six study sites of each 4° × 4° grids (mixed forest in China, deciduous needle-leaf forest in Siberia, evergreen needle-leaf forest in western Canada, grass in Gobi, and crops in the Central United States and southeastern Europe) include various vegetation types, local climates, and land-use types in the mid-latitudes of the northern hemisphere. Empirical orthogonal function (EOF) analysis with detrended LAI anomalies identified the two leading EOF modes that account for the amplitude and phase of the monthly LAI variations. The inter-annual correlation between the principle components (PCs) of the two modes and the meteorological variables for spring and summer showed that the amplitude and phase modes (AM and PM, respectively) were affected by different dominant meteorological factors. Over most of the study regions, AM was positively correlated with PRCP and negatively with Ts, SW, and VPD, while PM was predominantly positively correlated with Ts. The contrasting responses of the two EOF modes to Ts reflect environmental limitations on plant growth such as early start of growth, but with a reduced value of maximum LAI in a year with a warm spring. In addition, insignificant

  18. Seasonal and inter-annual variability of the aerosol content in Cairo (Egypt) as deduced from the comparison of MODIS aerosol retrievals with direct AERONET measurements

    NASA Astrophysics Data System (ADS)

    El-Metwally, M.; Alfaro, S. C.; Abdel Wahab, M. M.; Zakey, A. S.; Chatenet, B.

    2010-07-01

    As this is the case in many megacities of the developing countries, the atmospheric aerosol load is usually particularly large over the Cairo (Egypt) conurbation. However, being the result of a combination of meteorological factors and of the activity of various particle sources, some of which are seasonal, this load is variable in time. The objective of this study is to document this variability at the intra- and inter-annual scales. For this we use the qualitative Aerosol Absorption Index (AAI) derived from Aura-OMI (the ultimate version of the Total Ozone Mapping Spectrometer, TOMS) and the Aerosol Optical Depth (AOD) derived from the radiance measurements performed between 2000 and 2008 by the Moderate Resolution Imaging Spectroradiometers (MODIS) implemented aboard either the Terra or the Aqua satellites. In the sense that AOD maxima are always obtained in April and in October at the peaks of the desert dust and biomass burning periods, respectively, the results yielded by these two methods are in good qualitative agreement with those of direct sunphotometer observations performed in Cairo for more than one year (from end of October 2004 to the end of March 2006). However, a quantitative comparison of the MODIS and AERONET products for their common period of measurements reveals that MODIS tends to overestimate systematically the AOD and underestimate the aerosol's Ångström exponent. We propose an empirical method for correcting the AOD retrieved by MODIS at 550 nm and match it with the sunphotometer values. When applied to the whole MODIS dataset, the effect of this correction is to smooth the inter-annual differences. As a result, the month-to-month variations of the AOD can be described by the same pattern independently of the year in the period of study (from 2000 to 2008). The monthly averaged AOD obtained by this method is minimal (0.24 ± 0.04 at 550 nm) from December to February because of the washing out of airborne particles by rain events more

  19. The ScaLIng Macroweather Model (SLIMM) and monthly and inter annual regional forecasting.

    NASA Astrophysics Data System (ADS)

    Lovejoy, S.; Del Rio Amador, L.; Sloman, L.

    2015-12-01

    compare it with actual skill based on hindcasts for monthly, seasonal and annual resolutions. A comparison between our results and previous results using LIM or other GCM's is also shown. The prediction skill obtained for the temperature field have been improved by incorporating some other fields and performing an analogous analysis on the generalized state-vectors.

  20. Inter-annual surface evolution of an Antarctic blue-ice moraine using multi-temporal DEMs

    NASA Astrophysics Data System (ADS)

    Westoby, M. J.; Dunning, S. A.; Woodward, J.; Hein, A. S.; Marrero, S. M.; Winter, K.; Sugden, D. E.

    2015-11-01

    Multi-temporal and fine resolution topographic data products are being increasingly used to quantify surface elevation change in glacial environments. In this study, we employ 3-D digital elevation model (DEM) differencing to quantify the topographic evolution of a blue-ice moraine complex in front of Patriot Hills, Heritage Range, Antarctica. Terrestrial laser scanning (TLS) was used to acquire multiple topographic datasets of the moraine surface at the beginning and end of the austral summer season in 2012/2013 and during a resurvey field campaign in 2014. A complementary topographic dataset was acquired at the end of season 1 through the application of Structure-from-Motion (SfM) photogrammetry to a set of aerial photographs taken from an unmanned aerial vehicle (UAV). Three-dimensional cloud-to-cloud differencing was undertaken using the Multiscale Model to Model Cloud Comparison (M3C2) algorithm. DEM differencing revealed net uplift and lateral movement of the moraine crests within season 1 (mean uplift ∼ 0.10 m), with lowering of a similar magnitude in some inter-moraine depressions and close to the current ice margin. Our results indicate net uplift across the site between seasons 1 and 2 (mean 0.07 m). This research demonstrates that it is possible to detect dynamic surface topographical change across glacial moraines over short (annual to intra-annual) timescales through the acquisition and differencing of fine-resolution topographic datasets. Such data offer new opportunities to understand the process linkages between surface ablation, ice flow, and debris supply within moraine ice.

  1. Understanding the influence of global scale climate modes on inter-annual variability of African precipitation using CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, P. S.; Zaitchik, B.

    2013-12-01

    Continental Africa is characterized by considerable spatio-temporal variability of precipitation, which is associated with extreme events such as droughts and floods, that have serious impacts on environment, economy and society. Such variability in precipitation distribution, both in temporal and spatial scale, exerts a profound influence on local and regional water budget and on human and natural systems sensitive to climate variations at timescales of seasons to decades. The present study aims to quantify the large-scale processes that drive rainfall variability over Africa at seasonal and inter-annual timescales. We examine how well these processes are represented in the present generation of climate models for historical conditions and examine projection for mid-21st century. Ten coupled models in Climate Model Intercomparison Project (CMIP5) along with observational datasets of precipitation (Climate Research Unit (CRU)) and Reynolds sea surface temperature (SST) analysis are used to study and compare annual and seasonal variation of precipitation over Africa (between 1960-2005 time period). Principal component and correlation analysis performed on observational datasets show that El Niño/Southern Oscillation (ENSO) variability and global SST have a dominant impact on rainfall variability over Africa. As expected, models performing in CMIP5 vary greatly in their representation of SST variability, including that related to ENSO, as well as in the strength of association between SST variability and precipitation over various regions of Africa. Some models resemble the observed relationships while others associate African precipitation variability with other remote drivers. Under future conditions (RCP8.5 scenario, averaged between 2060-2099), some models project a maintenance or intensification of current associations while others project nonstationary change. We consider the implications of this diversity for climate impact studies and future model

  2. Inter-Annual Variability of Soil Moisture Stress Function in the Wheat Field

    NASA Astrophysics Data System (ADS)

    Akuraju, V. R.; Ryu, D.; George, B.; Ryu, Y.; Dassanayake, K. B.

    2014-12-01

    Root-zone soil moisture content is a key variable that controls the exchange of water and energy fluxes between land and atmosphere. In the soil-vegetation-atmosphere transfer (SVAT) schemes, the influence of root-zone soil moisture on evapotranspiration (ET) is parameterized by the soil moisture stress function (SSF). Dependence of actual ET: potential ET (fPET) or evaporative fraction to the root-zone soil moisture via SSF can also be used inversely to estimate root-zone soil moisture when fPET is estimated by remotely sensed land surface states. In this work we present fPET versus available soil water (ASW) in the root zone observed in the experimental farm sites in Victoria, Australia in 2012-2013. In the wheat field site, fPET vs ASW exhibited distinct features for different soil depth, net radiation, and crop growth stages. Interestingly, SSF in the wheat field presented contrasting shapes for two cropping years of 2012 and 2013. We argue that different temporal patterns of rainfall (and resulting soil moisture) during the growing seasons in 2012 and 2013 are responsible for the distinctive SSFs. SSF of the wheat field was simulated by the Agricultural Production Systems sIMulator (APSIM). The APSIM was able to reproduce the observed fPET vs. ASW. We discuss implications of our findings for existing modeling and (inverse) remote sensing approaches relying on SSF and alternative growth-stage-dependent SSFs.

  3. Steady inter and intra-annual decrease in the vocalization frequency of Antarctic blue whales.

    PubMed

    Gavrilov, Alexander N; McCauley, Robert D; Gedamke, Jason

    2012-06-01

    Time averaged narrow-band noise near 27 Hz produced by vocalizations of many distant Antarctic blue whales intensifies seasonally from early February to late October in the ocean off Australia's South West. Spectral characteristics of long term patterns in this noise band were analyzed using ambient noise data collected at the Comprehensive Nuclear-Test-Ban Treaty hydroacoustic station off Cape Leeuwin, Western Australia over 2002-2010. Within 7 day averaged noise spectra derived from 4096-point FFT (∼0.06 Hz frequency resolution), the -3-dB width of the spectral peak from the upper tone of Antarctic blue whale vocalization was about 0.5 Hz. The spectral frequency peak of this tonal call was regularly but not gradually decreasing over the 9 years of observation from ∼27.7 Hz in 2002 to ∼26.6 Hz in 2010. The average frequency peak steadily decreased at a greater rate within a season at 0.4-0.5 Hz/season but then in the next year recovered to approximately the mean value of the previous season. A regression analysis showed that the interannual decrease rate of the peak frequency of the upper tonal call was 0.135 ± 0.003 Hz/year over 2002-2010 (R(2) ≈ 0.99). Possible causes of such a decline in the whale vocalization frequency are considered. PMID:22712920

  4. Seasonal and Inter-Annual Changes in the Distribution of Dominant Phytoplancton Groups in the Global Ocean

    NASA Astrophysics Data System (ADS)

    Severine, A.; Cyril, M.; Yves, D.; Laurent, B.; Hubert, L.

    2006-12-01

    The fate of fixed organic carbon in the ocean strongly varies with the phytoplankton group that makes photosynthesis. The monitoring of phytoplankton groups in the global ocean is thus of primary importance to evaluate and improve ocean carbon models. A new method (PHYSAT; Alvain et al., 2005) enables to distinguish between four different groups from space using SeaWiFS ocean color measurements. In addition to these four initial phytoplankton groups, which are diatoms, Prochlorococcus, Synecochoccus and haptophytes, we show that PHYSAT is also capable of identifying blooms of phaeocystis and coccolithophorids. Daily global SeaWiFS level-3 data from September 1997 to December 2004 were processed using PHYSAT. We present here the first monthly mean global climatology of the dominant phytoplankton groups. The seasonal cycle is discussed, with particular emphasis on the succession of phytoplankton groups during the North Atlantic spring bloom and on the coexistence of large phaeocystis and diatoms blooms during winter in the Austral Ocean. We also present the inter-annual variability for the 1998-2004 period. The contribution of diatoms to the total chlorophyll is highly variable (up to a factor of two) from one year to the other in both Atlantic and Austral Oceans, suggesting a significant variability in organic carbon export by diatoms in these regions. On the opposite, the phaeocystis contribution is less variable in the Austral Ocean.

  5. Inter-annual Variations and Trend Analyses of Precipitation and Vapor Isotopes with a Global Isotope Circulation Model and Observations

    NASA Astrophysics Data System (ADS)

    Yoshimura, K.; Oki, T.

    2006-12-01

    An atmosphere, land, sea surface, and river-coupled global isotope circulation model has been developed and it successfully reproduced spatial distribution of precipitation and vapor isotopes as well as those of "real" daily to inter-annual cycles provided by GNIP. A relationship between ENSO and simulated isotope ratio anomaly shows significant signals in DJF. They show lows in Greenland, southern USA and center of the Pacific, and highs in the northern North America, South America, and center of Asia in El Nino periods. Mostly vice versa in La Nina periods. In low latitude zones, it corresponds with the anomaly variations of precipitation amount, but in high latitudes, isotopes show original information on complex water circulation. Further investigation will be done by the presentation. Long-term trends of anomaly of precipitation isotopes are interesting, too. The observation show significant increase of precipitation isotope ratio over west Europe and the simulation agrees with it. Very simply speaking, when hydrologic cycle is enhanced, precipitation isotope will be increased, because the residence time of vapor becomes shorter. The trends in GNIP and the model is well agreed with Dirmeyer and Brubaker's (2006) finding the increase trend of recycling ratio in Northern Hemisphere. GNIP, we often regard it as "already understood", still has unknown to be tackled with.

  6. Satellite observations reveal little inter-annual variability in the radiant flux from the Mount Erebus lava lake

    NASA Astrophysics Data System (ADS)

    Wright, Robert; Pilger, Eric

    2008-11-01

    Satellite remote sensing represents a mature technology for long-term monitoring of volcanic activity at Mount Erebus, either independently or as a complement to field instrumentation. Observations made on 4290 discrete occasions over a six year period by NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) indicate that the radiant flux from the volcano's summit crater (and by inference, the lava lake contained therein), while variable on the time scale of days to weeks, has varied little on an inter-annual basis over this period. The average radiant flux from the lake during this time was 15 MW, with a maximum flux of 100 MW. Such heat flux time-series have been shown to act as a reliable proxy for general levels of activity at erupting volcanoes around the world, particularly when these time-series are of a long duration. The apparent stability of Erebus' power output is in marked contrast to fluxes observed at three other terrestrial volcanoes, Erta 'Ale (Ethiopia), Nyiragongo (Democratic Republic of Congo) and Ambrym (Vanuatu), which, while also hosting active lava lakes, all exhibit much greater variability in radiant flux over the same period of time. The results presented in this paper are confluent with those obtained from geochemical considerations of the Erebus' degassing regime, and confirm that remarkably stable open-system volcanism appears to be characteristic of this long-active volcano.

  7. Inter-annual variability of exchange processes at the outer Black Sea shelf

    NASA Astrophysics Data System (ADS)

    Shapiro, Georgy; Wobus, Fred; Yuan, Dongliang; Wang, Zheng

    2014-05-01

    vertical discretisation (s-on-top-of-z) and other improved parameters of the model set-up as in Shapiro et al. (2013). The model was run for the period from 1979 to 2012 with water discharges from 8 main rivers, exchanges through Bosporus and meteo forcing from the Drakkar Forcing Set 5.2 (Brodeau et al, 2010). The model was spun-up from climatological temperature and salinity in January using a semi-diagnostic adjustment method. Each annual simulation started from the same initial state on 1 January without data assimilation. The data for the warm period from 1 May to 31 October of each year were used for the following analysis. The model has been validated against in-situ (based on 77867 stations) and night-time satellite monthly mean SST observations. The model also captures well the major features seen on snapshot satellite images. A simulated daily climatology was created by averaging the temperature values over the 34-year simulation. Anomalies were calculated as the deviations of the snapshot temperatures from their climatological values. The correlation between the temperature anomalies of BSW on the outer shelf and those in the CIL waters in the deep sea were computed as well as water transports between these water masses across the shelf break. The BSW on the outer shelf are defined as the waters between the density level σθ=14.2 kg m3 (i.e. the bottom of the surface mixed layer) and the seabed (max z=150 m at the shelf break). The corresponding data from open sea CIL waters in the northwest part of the deep Black Sea were taken from the depth range between σθ=14.2 and z=150 m. The computed Pierson correlation between summer temperatures of BSW and the deep sea CIL is R = 0.90. This significant correlation is in agreement with the analysis from observational data of Shapiro et al. (2011). In order to reveal a physical link between the BSW and CIL, the in-out transports of water with σθ ≥14.2 across the shelf break were computed for each day and then

  8. Inter-annual variability of evapotranspiration in two semiarid ecosystems with different climate patterns

    NASA Astrophysics Data System (ADS)

    Villarreal, S.; Vargas, R.; Yepez, E. A.; Smith, S. V.; Watts, C.; Rodriguez, J.; Garatuza, J.; Martinez, J.; Castro, A.; Lopez, E.

    2012-12-01

    One of the most important climatic characteristics in arid and semiarid environments is the amount and variability of precipitation. This characteristic is important because the variability, magnitude, and number of the precipitation pulses have differing influence on the evapotranspiration flux (ET). We demonstrated this by studying two different semiarid shrublands : one with cool and wet winters (El Mogor), and the other with wet and warm summers (Rayon). We were interested in: a) the behavior of evapotranspiration (ET) when the wet season is in phase with the highest values of net radiation (Rayon), and when these two variables were not in phase (El Mogor); and b) on the interannual transition between dry-wet and wet-dry season. We used six site-years of eddy covariance measurements of ET from 2008-2010 (i.e.,3 years of measurements per site). Preliminary results show that Rayon has a maximum ET during the wet season, while El Mogor has it during the wet-dry transition. We discuss that maximum ET is controlled by precipitation and net radiation, but volumetric water content is a strong environmental control on ET especially during the transition seasons.

  9. Effects of clouds on the Earth radiation budget; Seasonal and inter-annual patterns

    NASA Technical Reports Server (NTRS)

    Dhuria, Harbans L.

    1992-01-01

    Seasonal and regional variations of clouds and their effects on the climatological parameters were studied. The climatological parameters surface temperature, solar insulation, short-wave absorbed, long wave emitted, and net radiation were considered. The data of climatological parameters consisted of about 20 parameters of Earth radiation budget and clouds of 2070 target areas which covered the globe. It consisted of daily and monthly averages of each parameter for each target area for the period, Jun. 1979 - May 1980. Cloud forcing and black body temperature at the top of the atmosphere were calculated. Interactions of clouds, cloud forcing, black body temperature, and the climatological parameters were investigated and analyzed.

  10. Evaluating the effects of China's pollution control on inter-annual trends and uncertainties of atmospheric mercury emissions

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhong, H.; Zhang, J.; Nielsen, C. P.

    2014-10-01

    China's atmospheric mercury (Hg) emissions of anthropogenic origin have been effectively restrained through the national policy of air pollution control. Improved methods based on available field measurements are developed to quantify the benefits of Hg abatement through various emission control measures. Those measures include increased use of flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems for power sector, precalciners with fabric filter (FF) for cement production, machinery coking with electrostatic precipitator (ESP) for iron and steel production, and advanced manufacturing technologies for nonferrous metal smelting. Declining trends in emissions factors for those sources are revealed, leading to a much slower growth of national total Hg emissions than that of energy and economy, from 679 in 2005 to 750 metric tons (t) in 2012. In particular, nearly half of emissions from the above-mentioned four types of sources are expected to be reduced in 2012, attributed to expansion of technologies with high energy efficiencies and air pollutant removal rates after 2005. The speciation of Hg emissions keeps stable for recent years, with the mass fractions of around 55, 39 and 6% for Hg0, Hg2+ and Hgp, respectively. The lower estimate of Hg emissions than previous inventories is supported by limited chemistry simulation work, but middle-to-long term observation on ambient Hg levels is further needed to justify the inter-annual trends of estimated Hg emissions. With improved implementation of emission controls and energy saving, 23% reduction in annual Hg emissions for the most optimistic case in 2030 is expected compared to 2012, with total emissions below 600 t. While Hg emissions are evaluated to be gradually constrained, increased uncertainties are quantified with Monte-Carlo simulation for recent years, particularly for power and certain industrial sources. The uncertainty of Hg emissions from coal-fired power plants, as an example

  11. Hydroclimatic Controls on the Seasonal and Inter-Annual Variability of Dissolved Phosphorus Concentration in a Lowland Agricultural Catchment

    NASA Astrophysics Data System (ADS)

    Dupas, R.; Gascuel-odoux, C.; Grimaldi, C.; Gruau, G.

    2014-12-01

    We investigated soluble reactive phosphorus (SRP) at the outlet of a lowland agricultural catchment (Kervidy-Naizin, France) to identify the hydroclimatic controls on the seasonal and inter-annual variability in concentrations. Six years of stream data have been used, including a regular 6-daily sampling and high-frequency monitoring of 52 floods. Both on an annual basis and during flood events, distinct export dynamics for SRP and particulate phosphorus (PP) revealed that SRP transport mechanism was independent from PP (Dupas et al., submitted). During most flood events, discharge-SRP hystereses were anticlockwise, which suggests that SRP was transferred to the stream via subsurface flow. Groundwater rise in wetland soils was likely the cause of this transfer, through the hydrological connectivity it created between the stream and P-rich soil horizons. SRP concentrations were highest in the beginning of the hydrological year (period A), when the stream started to flow again after the dry summer season and water table fluctuated in the wetland domain. Thus, wetland soils seemed to be a major source of SRP. Concentrations during period A were higher after a long summer period than after a short one, which suggest that a pool of labile P was constituted in soils during the dry summer period. During winter (period B), SRP concentration generally decreased compared to period A, both during floods and interflood. This could be due to depletion of a soil P pool in the wetland domain and/or dilution by deep groundwater with low P concentration from the upland domain. Concentration during period B barely decreased compared to A during wet years, probably due to increased connectivity with soils from the upland domain in wet conditions. During spring (period C), SRP concentration increased during baseflow periods. The possible mechanisms causing the release of SRP could involve reduction of Fe oxide-hydroxides in wetland soils or in-stream processes. At the same time, SRP

  12. Impact of Precipitation Patterns on Biomass and Species Richness of Annuals in a Dry Steppe

    PubMed Central

    Yan, Hong; Liang, Cunzhu; Li, Zhiyong; Liu, Zhongling; Miao, Bailing; He, Chunguang; Sheng, Lianxi

    2015-01-01

    Annuals are an important component part of plant communities in arid and semiarid grassland ecosystems. Although it is well known that precipitation has a significant impact on productivity and species richness of community or perennials, nevertheless, due to lack of measurements, especially long-term experiment data, there is little information on how quantity and patterns of precipitation affect similar attributes of annuals. This study addresses this knowledge gap by analyzing how quantity and temporal patterns of precipitation affect aboveground biomass, interannual variation aboveground biomass, relative aboveground biomass, and species richness of annuals using a 29-year dataset from a dry steppe site at the Inner Mongolia Grassland Ecosystem Research Station. Results showed that aboveground biomass and relative aboveground biomass of annuals increased with increasing precipitation. The coefficient of variation in aboveground biomass of annuals decreased significantly with increasing annual and growing-season precipitation. Species richness of annuals increased significantly with increasing annual precipitation and growing-season precipitation. Overall, this study highlights the importance of precipitation for aboveground biomass and species richness of annuals. PMID:25906187

  13. Impact of precipitation patterns on biomass and species richness of annuals in a dry steppe.

    PubMed

    Yan, Hong; Liang, Cunzhu; Li, Zhiyong; Liu, Zhongling; Miao, Bailing; He, Chunguang; Sheng, Lianxi

    2015-01-01

    Annuals are an important component part of plant communities in arid and semiarid grassland ecosystems. Although it is well known that precipitation has a significant impact on productivity and species richness of community or perennials, nevertheless, due to lack of measurements, especially long-term experiment data, there is little information on how quantity and patterns of precipitation affect similar attributes of annuals. This study addresses this knowledge gap by analyzing how quantity and temporal patterns of precipitation affect aboveground biomass, interannual variation aboveground biomass, relative aboveground biomass, and species richness of annuals using a 29-year dataset from a dry steppe site at the Inner Mongolia Grassland Ecosystem Research Station. Results showed that aboveground biomass and relative aboveground biomass of annuals increased with increasing precipitation. The coefficient of variation in aboveground biomass of annuals decreased significantly with increasing annual and growing-season precipitation. Species richness of annuals increased significantly with increasing annual precipitation and growing-season precipitation. Overall, this study highlights the importance of precipitation for aboveground biomass and species richness of annuals. PMID:25906187

  14. Inter-annual variability of stream temperature, micro-climate and heat exchange dynamics: a comparison of forest and moorland environments

    NASA Astrophysics Data System (ADS)

    Garner, G.; Hannah, D. M.; Malcolm, I. A.; Sadler, J. P.

    2012-04-01

    Riparian woodland is recognised as important in moderating stream temperature variability and offers potential to mitigate thermal extremes under a warming climate. Previous research on the heat exchanges determining water column temperature has been often short-term, or seasonally-constrained, with the few long term year-round studies limited to a maximum of two years. This paper addresses these research gaps by comparing inter-annual variability in stream temperature, micro-climate and heat exchange dynamics between stream reaches of contrasting riparian landuse. Automatic weather stations (AWS) were installed in semi-natural woodland and moorland (no trees) reaches of the Girnock Burn, an upland tributary of the Aberdeenshire Dee. Data were collected across all seasons over seven calendar years. This research yields, for the first time, a long-term perspective on temporal differences in river heat exchange processes associated with riparian landuse under a range of hydroclimatological conditions. Results indicate that the presence of a riparian canopy has a persistent effect year-to-year in reducing mean and maximum daily water column temperature under a variety of hydrological and meteorological conditions. Woodland and moorland reaches display similar inter-annual variability in daily water column temperature range during spring and early summer, but in mid-summer and autumn woodland inter-annual variability is reduced greatly compared with moorland. Higher inter-annual variability (indicated by standard deviations) in spring and early summer water temperature ranges at both sites are attributed to increasing day length and solar radiation receipt, which a developing forest canopy at the woodland site is not able to mitigate. Once the full riparian canopy, hence maximum shading potential, is established (mid-summer) inter-annual variability in woodland temperature range is reduced greatly. The magnitude of woodland water temperature range is greater in spring

  15. Climate and the Individual: Inter-Annual Variation in the Autumnal Activity of the European Badger (Meles meles)

    PubMed Central

    Noonan, Michael J.; Markham, Andrew; Newman, Chris; Trigoni, Niki; Buesching, Christina D.; Ellwood, Stephen A.; Macdonald, David W.

    2014-01-01

    We establish intra-individual and inter-annual variability in European badger (Meles meles) autumnal nightly activity in relation to fine-scale climatic variables, using tri-axial accelerometry. This contributes further to understanding of causality in the established interaction between weather conditions and population dynamics in this species. Modelling found that measures of daylight, rain/humidity, and soil temperature were the most supported predictors of ACTIVITY, in both years studied. In 2010, the drier year, the most supported model included the SOLAR*RH interaction, RAIN, and30cmTEMP (w = 0.557), while in 2012, a wetter year, the most supported model included the SOLAR*RH interaction, and the RAIN*10cmTEMP (w = 0.999). ACTIVITY also differed significantly between individuals. In the 2012 autumn study period, badgers with the longest per noctem activity subsequently exhibited higher Body Condition Indices (BCI) when recaptured. In contrast, under drier 2010 conditions, badgers in good BCI engaged in less per noctem activity, while badgers with poor BCI were the most active. When compared on the same calendar dates, to control for night length, duration of mean badger nightly activity was longer (9.5 hrs ±3.3 SE) in 2010 than in 2012 (8.3 hrs ±1.9 SE). In the wetter year, increasing nightly activity was associated with net-positive energetic gains (from BCI), likely due to better foraging conditions. In a drier year, with greater potential for net-negative energy returns, individual nutritional state proved crucial in modifying activity regimes; thus we emphasise how a ‘one size fits all’ approach should not be applied to ecological responses. PMID:24465376

  16. Fluctuations in annual cycles and inter-seasonal memory in West Africa: rainfall, soil moisture and heat fluxes

    NASA Astrophysics Data System (ADS)

    Fontaine, B.; Louvet, S.; Roucou, P.

    2007-01-01

    Annual cycle and inter-seasonal persistence of surface-atmosphere water and heat fluxes are analyzed at a 5-day time step over the West African Monsoon (WAM) through observational precipitation estimates (CMAP), model datasets (NCEP/DOE level 2 reanalyses) and a Soil Water Index (SWI) from the ERS scatterometer. Coherent fluctuations (30-90 days) distinct from supra-synoptic variability (10-25 day periods) are first detected in the WAM precipitation and heat fluxes over the period 1979-2001. During all the northward excursion of the WAM rain band, a succession of four active phases (abrupt rainfall increases) occurs. They are centered in the first days of March, mid-April, the second half of May and from the last week of June to mid-July (the Sahelian onset). A simple statistical approach shows that the Spring to Summer installation of the monsoon tends to be sensitive to these short periods. Other analyses suggest the existence of lagged relationship between rainfall amounts registered in successive Fall, Spring (active periods) and Summer (top of the rainy season) implying land surface conditions. The spatial extension of the generated soil moisture anomalies reaches one maximum in March, mainly at the Guinean latitudes and over the Sahelian belt where the signal can persist until the next monsoon onset. Typically after abnormal wet conditions in September-October two signals are observed: (1) more marked fluctuations in Spring with less (more) Sahelian rainfall in May (June and after) at the Sahelian-Sudanian latitudes; (2) wetter rainy seasons along the Guinean coast (in Spring and Summer with an advance in the mean date of the ‘little dry season’). The reverse arises after abnormal dry conditions in autumn.

  17. Predicting Distribution and Inter-Annual Variability of Tropical Cyclone Intensity from a Stochastic, Multiple-Linear Regression Model

    NASA Astrophysics Data System (ADS)

    Lee, C. Y.; Tippett, M. K.; Sobel, A. H.; Camargo, S. J.

    2014-12-01

    We are working towards the development of a new statistical-dynamical downscaling system to study the influence of climate on tropical cyclones (TCs). The first step is development of an appropriate model for TC intensity as a function of environmental variables. We approach this issue with a stochastic model consisting of a multiple linear regression model (MLR) for 12-hour intensity forecasts as a deterministic component, and a random error generator as a stochastic component. Similar to the operational Statistical Hurricane Intensity Prediction Scheme (SHIPS), MLR relates the surrounding environment to storm intensity, but with only essential predictors calculated from monthly-mean NCEP reanalysis fields (potential intensity, shear, etc.) and from persistence. The deterministic MLR is developed with data from 1981-1999 and tested with data from 2000-2012 for the Atlantic, Eastern North Pacific, Western North Pacific, Indian Ocean, and Southern Hemisphere basins. While the global MLR's skill is comparable to that of the operational statistical models (e.g., SHIPS), the distribution of the predicted maximum intensity from deterministic results has a systematic low bias compared to observations; the deterministic MLR creates almost no storms with intensities greater than 100 kt. The deterministic MLR can be significantly improved by adding the stochastic component, based on the distribution of random forecasting errors from the deterministic model compared to the training data. This stochastic component may be thought of as representing the component of TC intensification that is not linearly related to the environmental variables. We find that in order for the stochastic model to accurately capture the observed distribution of maximum storm intensities, the stochastic component must be auto-correlated across 12-hour time steps. This presentation also includes a detailed discussion of the distributions of other TC-intensity related quantities, as well as the inter-annual

  18. Accounting for inter-annual and seasonal variability in regionalization of hydrologic response in the Great Lakes basin

    NASA Astrophysics Data System (ADS)

    Kult, J. M.; Fry, L. M.; Gronewold, A. D.

    2012-12-01

    Methods for predicting streamflow in areas with limited or nonexistent measures of hydrologic response typically invoke the concept of regionalization, whereby knowledge pertaining to gauged catchments is transferred to ungauged catchments. In this study, we identify watershed physical characteristics acting as primary drivers of hydrologic response throughout the US portion of the Great Lakes basin. Relationships between watershed physical characteristics and hydrologic response are generated from 166 catchments spanning a variety of climate, soil, land cover, and land form regimes through regression tree analysis, leading to a grouping of watersheds exhibiting similar hydrologic response characteristics. These groupings are then used to predict response in ungauged watersheds in an uncertainty framework. Results from this method are assessed alongside one historical regionalization approach which, while simple, has served as a cornerstone of Great Lakes regional hydrologic research for several decades. Our approach expands upon previous research by considering multiple temporal characterizations of hydrologic response. Due to the substantial inter-annual and seasonal variability in hydrologic response observed over the Great Lakes basin, results from the regression tree analysis differ considerably depending on the level of temporal aggregation used to define the response. Specifically, higher levels of temporal aggregation for the response metric (for example, indices derived from long-term means of climate and streamflow observations) lead to improved watershed groupings with lower within-group variance. However, this perceived improvement in model skill occurs at the cost of understated uncertainty when applying the regression to time series simulations or as a basis for model calibration. In such cases, our results indicate that predictions based on long-term characterizations of hydrologic response can produce misleading conclusions when applied at shorter

  19. Seasonal and inter-annual variability in nutrient supply in relation to mixing in the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    Hartman, Susan E.; Hartman, Mark C.; Hydes, David J.; Jiang, Zong-Pei; Smythe-Wright, Denise; González-Pola, Cesar

    2014-08-01

    A key challenge in oceanography is to capture and quantify processes that happen on short time scales, seasonal changes and inter-annual variations. To address this problem the P&O European Ferries Ltd. Ship MV Pride of Bilbao was fitted with a FerryBox from 2002 to 2010 and data returned to NOC in real time providing near continuous measurements between UK (Portsmouth) and Spain (Bilbao) of temperature, salinity, chlorophyll-fluorescence and oxygen. Additional monthly samples were collected on manned crossings. Over 6000 samples were analysed for nitrate (nitrate and nitrite) concentrations. The timing of nitrate concentration increases (with winter mixing) and decreases (with the spring bloom) are different on and off shelf and in autumn nitrate concentrations remain high on the shelf. Off shelf in the Bay of Biscay, the mixed layer depth assessed using Argo floats, was found to vary from 212 m in relatively mild winters (such as 2007/2008) to 476 m in cold winters (2009/2010). Years with deeper mixing were associated with an increase in nitrate concentrations in the surface waters (~3 μmol l-1) and the increased vertical nutrient supply resulted in higher productivity the following spring. Bloom progression could be seen through the increase in oxygen anomaly and decrease in nitrate concentrations off shelf prior to changes further north on the shelf and phytoplankton growth was initiated as shoaling begins. The full dataset demonstrates that ships of opportunity, particularly ferries with consistently repeated routes, can deliver high quality in situ measurements over large time and space scales that currently cannot be delivered in any other way.

  20. Inter-regional comparison of patterns and trends in surface water acidification across the United States

    SciTech Connect

    Newell, A.D.

    1993-01-01

    Temporal trends in acid-base chemistry are reported for surface waters in 6 regions of the United States. The lakes and streams are low acid neutralizing capacity (ANC), dilute systems, selected to represent acid-sensitive aquatic resources in the 6 regions. The predominant trends observed were decreases in lake and stream SO4(2-) concentrations in sites east of the Mississippi River, and increases in NO3(-) in the Adirondack lake and Catskill stream sites (both located in eastern New York State). Correlations of trend results from all sites with other factors indicated that trends in precipitation volume were highly correlated with the observed trend patterns. From the surface water trend results, three distinct clusters were identified that corresponded to three trend patterns: 'dilution', recovery', and 'acidification', which were distributed across the Long-Term Monitoring (LTM) regions with no particular geographic patterns. (Copyright (c) 1993 Kluwer Academic Publishers.)

  1. Seasonal and inter-annual variability of sea surface temperature at the east coast fishing area off Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Nurul Ridani, S.; Mustapha, M. A.; Lihan, T.; Ku Kassim, K. Y.; Raja Bidin, R. H.

    2015-09-01

    Empirical orthogonal function (EOF) analysis was used to study a time-series of the aqua MODIS data imageries in the exclusive economic zone of east coast off Peninsular Malaysia. Temporal and spatial characteristics were examined to determine the dominant pattern of sea surface temperature (SST) variability from January 2003 to December 2011.The data were analysed from daily Level 1A (1km spatial resolution) to monthly composites Level 3 data using SeaDAS and ERDAS imagine software. Four modes was obtained from the analysis with the highest variance (7.9%) represented by mode 1 which explained the seasonal cycle. Mode 2 (5.11 % of total variance) showed positive and negative peak signal during March and April and in October and November with variability near the Kelantan and Pahang waters that indicated the inter monsoon. Mode 3 (3.8 % of variance) shows variability near the Terengganu, Kelantan and Johor waters to the open sea during July and August and in May and June representing the Southwest monsoon. Mode 4 (3.36 %) showed positive signal during November and December with strong signal near Pahang and Kelantan waters while weak signal was detected near Terengganu and Kelantan's open sea representing the Northeast monsoon. The SST variability was influenced by the monsoonal system which originated by the wind forcing condition that influences circulation in the study area.

  2. Intra-annual patterns in adult band-tailed pigeon survival estimates

    USGS Publications Warehouse

    Casazza, Michael L.; Coates, Peter S.; Overton, Cory T.; Howe, Kristy H.

    2015-01-01

    Implications: We present the first inter-seasonal analysis of survival probability of the Pacific coast race of band-tailed pigeons and illustrate important temporal patterns that may influence future species management including harvest strategies and disease monitoring.

  3. Response of riparian vegetation across Australia's largest river basin to inter and intra-annual flooding: dynamics quantified from time series of Landsat and MODIS data

    NASA Astrophysics Data System (ADS)

    Broich, M.; Tulbure, M. G.; Keith, D.; Kingsford, R.; Lucas, R.; Lippmann, T.

    2014-12-01

    Australia is a continent subject to high rainfall variability. The resulting spatial-temporal pattern of flooding and its influence on riparian vegetation has not been quantified. Here we focused on the floodplains of the entire Murray-Darling Basin (MDB; 72 Landsat path-rows) of Australia as a case study. The MDB is the country's primary agricultural area with scarce water resources impacted by climate change and extensive zones with degrading riparian vegetation. We advance our understanding of the relationship between climate-driven flooding dynamics and vegetation response at the sub-continental to local and inter to intra-annual scale based on two decades of Landsat and one decade of MODIS imagery. We Landsat TM and ETM+ data to synoptically map spatially detailed dynamics of flooding with an internally consistent machine learning algorithm. We derived riparian phenology (Fig 1) from MODIS data and attributed differences in vegetation response to flooding dynamics, vegetation types and sub-basin land use. Vegetation community response to flooding varied in space and time and with vegetation types, densities and location relative to areas frequently flooded. Phenological degradation trends were observed over riparian forests and woodlands in the middle and lower parts of the basin that are primarily farmed and were we identified flooding regimes to have changed the most to less frequent and smaller inundation extents. Conversely, herbaceous vegetation phenology followed primarily a boom and bust cycle related to less extensive flooding dynamics. This pattern was found across different areas of the basin. As expected, flooding regimes and vegetation response patterns were fine grained confirming the choice of a spatially explicit, internally consistent analysis leading the path for ongoing monitoring. Remote sensing-based monitoring of the response of riparian vegetation to flooding can be used to quantify spatially explicit changes in vegetation community

  4. Inter-annual variability of precipitation over Southern Mexico and Central America and its relationship to sea surface temperature from a set of future projections from CMIP5 GCMs and RegCM4 CORDEX simulations

    NASA Astrophysics Data System (ADS)

    Fuentes-Franco, Ramón; Coppola, Erika; Giorgi, Filippo; Pavia, Edgar G.; Diro, Gulilat Tefera; Graef, Federico

    2015-07-01

    An ensemble of future climate projections performed with the regional climate model RegCM4 is used to assess changes in inter-annual variability of precipitation over Southern Mexico and Central America (SMECAM). Two different Global Climate Models (GCMs) from the coupled model intercomparison project phase 5 are used to provide boundary conditions for two different RegCM4 configurations. This results in four regional climate projections extending from 1970 to 2100 for the greenhouse gas representative concentration pathway RCP8.5. The precipitation variability over the SMECAM region and its dependence on the gradient between Atlantic and Pacific sea surface temperature (SST) anomalies are verified by reproducing SST anomaly patterns during wettest and driest years similar to those seen in observational datasets. RegCM4 does a comparably better job than the driving GCMs. This strong relationship between precipitation and SST anomalies does not appear to change substantially under future climate conditions. For the rainy season, June to September, we find a future change in inter-annual variability of precipitation towards a much greater occurrence of very dry seasons over the SMECAM region, with this change being more pronounced in the regional than in the global model projections. A greater warming of the Tropical Northeastern Pacific (TNP) compared to the Tropical North Atlantic (TNA), which causes stronger wind fluxes from the TNA to the TNP through the Caribbean Low Level Jet, is identified as the main process responsible for these drier conditions.

  5. Statistics and dynamics of attractor networks with inter-correlated patterns

    NASA Astrophysics Data System (ADS)

    Kropff, E.

    2007-02-01

    In an embodied feature representation view, the semantic memory represents concepts in the brain by the associated activation of the features that describe it, each one of them processed in a differentiated region of the cortex. This system has been modeled with a Potts attractor network. Several studies of feature representation show that the correlation between patterns plays a crucial role in semantic memory. The present work focuses on two aspects of the effect of correlations in attractor networks. In first place, it assesses how a Potts network can store a set of patterns with non-trivial correlations between them. This is done through a simple and biologically plausible modification to the classical learning rule. In second place, it studies the complexity of latching transitions between attractor states, and how this complexity can be controlled.

  6. Inter-annual precipitation variabiity inferred from late Holocene speleothem records from Fiji: implications for SPCZ localisation and ENSO behaviour

    NASA Astrophysics Data System (ADS)

    Mattey, D.; Stephens, M.; Hoffmann, D.; Brett, M.

    2015-12-01

    The modern tropical Fiji climate is characterised by seasonal rainfall controlled by the position of the South Pacific Convergence Zone (SPCZ). Interannual rainfall is strongly modulated on decadal timescales by ENSO with higher rainfall associated with La Nina events. Voli Voli cave near Sigatoga (Viti Levu) is a stream passage that has been monitored since 2009. A U-Th dated laminated speleothem spans a 1500 year interval across the transition from the Medieval Warm Period into the Little Ice Age marked by a fabric change from finely laminated calcite with thin clay layers, to white well-laminated calcite. The older record is characterised by rising δ13C values followed by a rapid decrease in δ13C around 1200 AD. Evidence from cave monitoring shows that cave air CO2 levels are strongly seasonal as a result of greater ventilation by winter trade winds and high resolution δ13C record shows regularly spaced peaks correlated with paired laminae and cycles in P and S which provide annual markers driven by rainfall and seasonal ventilation. δ18O values remain relatively unchanged throughout the record but micromilling at sub-annual resolution reveals systematic cycles in δ18O that span groups of paired laminae with an inferred periodicity of 3-7 years i.e. a similar frequency to modern ENSO. The presence of these sub-decadal cycles in δ18O may be a result of a combination of factors. The amplitude of 2-3‰ would be equivalent to an amount-effect related change in annual precipitation of around 50% but an additional smoothing process, perhaps a result of aquifer storage, is required to attenuate interannual variance in precipitation. The Voli Voli record provides evidence of an underlying climatic change to more frequent La Niña conditions from 1200 AD and may be associated with increased conflict, shifts in settlements and changes in subsistence strategies on the island. Coeval speleothem isotope records from tropical Pacific Islands provide a provide a

  7. Twenty-year inter-annual trends and seasonal variations in precipitation and stream water chemistry at the Bear Brook Watershed in Maine, USA.

    PubMed

    Navrátil, Tomas; Norton, Stephen A; Fernandez, Ivan J; Nelson, Sarah J

    2010-12-01

    Mean annual concentration of SO4(-2) in wet-only deposition has decreased between 1988 and 2006 at the paired watershed study at Bear Brook Watershed in Maine, USA (BBWM) due to substantially decreased emissions of SO(2). Emissions of NO(x) have not changed substantially, but deposition has declined slightly at BBWM. Base cations, NH4+, and Cl(-) concentrations were largely unchanged, with small irregular changes of <1 μeq L(-1) per year from 1988 to 2006. Precipitation chemistry, hydrology, vegetation, and temperature drive seasonal stream chemistry. Low flow periods were typical in June-October, with relatively greater contributions of deeper flow solutions with higher pH; higher concentrations of acid-neutralizing capacity, Si, and non-marine Na; and low concentrations of inorganic Al. High flow periods during November-May were typically dominated by solutions following shallow flow paths, which were characterized by lower pH and higher Al and DOC concentrations. Biological activity strongly controlled NO3- and K(+). They were depressed during the growing season and elevated in the fall. Since 1987, East Bear Brook (EB), the reference stream, has been slowly responding to reduced but still elevated acid deposition. Calcium and Mg have declined fairly steadily and faster than SO4(-2), with consequent acidification (lower pH and higher inorganic Al). Eighteen years of experimental treatment with (NH(4))(2)SO(4) enhanced acidification of West Bear Brook's (WB) watershed. Despite the manipulation, NH4+ concentration remained below detection limits at WB, while leaching of NO3- increased. The seasonal pattern for NO3- concentrations in WB, however, remained similar to EB. Mean monthly concentrations of SO4(-2) have increased in WB since 1989, initially only during periods of high flow, but gradually also during base flow. Increases in mean monthly concentrations of Ca(2+), Mg(2+), and K(+) due to the manipulation occurred from 1989 until about 1995, during the

  8. Eddy permitting simulation of the global ocean model COCO4.3 driven by the CORE inter- annual forcing

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Hasumi, H.; Komuro, Y.; Sakamoto, T. T.

    2008-12-01

    We are developing ocean component of the CCSR/NIES/FRCGC climate model to conduct high-resolution global warming simulations under IPCC scenarios. This presentation focuses on the performance and the behavior and role of eddies in the global ocean. The Ocean model is CCSR Ocean Component Model (COCO) version 4.3, which is a z-coordinate, free-surface primitive equation ocean model with multi-category sea ice model. The geographical North Pole is moved to 40W, 77N on Greenland and the geographical South Pole is moved to 40E, 77S. The computational domain covers global ocean, with zonal grid spacing of 0.28125 degree and meridional grid spacing of 0.1875 degree. There are 50 vertical levels excluding the bottom boundary layer, and 7 of which are within the sigma-coordinate (~42m). The model employs the momentum advection algorithm of Ishizaki and Motoi (1991), which is a pseudo-enstrophy preserving scheme with a consideration for up-/down-sloping advection. The model's tracer advection is based on the second-order moment (SOM) advection scheme of Prather, M. J. (1986). The vertical mixing of momentum and tracers is represented by a harmonic form. The coefficients are calculated by the parameterization of Noh and Kim (1999), but the formulation is slightly modified (see K1-developers, 2004). As background diffusivity, a minimum value is set for each level, suggested by Tsujino et al. (2000). The Smagorinsky's (1963) biharmonic viscosity is applied for the lateral momentum mixing, and its coefficient is dependent on the grid width and the strain rate, and its controlled by a single non- dimensional parameter whose values is taken to be 2.5. The constant coefficient biharmonic diffusion is applied with the coefficient value of 1.0E9 m4/s. The model is driven by the inter-annual forcing data set adopted by common ocean-ice reference experiments (CORE). The results are reported by focusing on heat transport in strong eddy activity regions, such as the Kuroshio

  9. Impacts of high inter-annual variability of rainfall on a century of extreme hydrologic regime of northwest Australia

    NASA Astrophysics Data System (ADS)

    Rouillard, A.; Skrzypek, G.; Dogramaci, S.; Turney, C.; Grierson, P. F.

    2015-04-01

    Long-term hydrologic records provide crucial reference baselines of natural variability that can be used to evaluate potential changes in hydrologic regimes and their impacts. However, there is a dearth of studies of the hydrologic regimes for tropical drylands where intraseasonal and interannual variability in magnitude and frequency of precipitation are extreme. Here, we sought to identify the main hydroclimatic determinants of the strongly episodic flood regime of a large catchment in the semi-arid, subtropical northwest of Australia and to establish the background of hydrologic variability for the region over the last century. We used a monthly sequence of satellite images to quantify surface water expression on the Fortescue Marsh, the largest water feature of inland northwest Australia, from 1988 to 2012. We used this sequence together with instrumental rainfall data to build a statistical model with multiple linear regression and reconstruct monthly history of floods and droughts since 1912. We found that severe and intense regional rainfall events, as well as the sequence of recharge events both within and between years, determine surface water expression on the floodplain (i.e. total rainfall, number of rain days and carried-over inundated area; R2adj = 0.79; p value < 0.001, ERMSP = 56 km2). The most severe reconstructed inundation over the last century was in March 2000 (1000 km2), which is less than the 1300 km2 area required to overflow to the adjacent catchment. The Fortescue Marsh was completely dry for 32% of all years, for periods of up to four consecutive years. Extremely wet years (seven of the 100 years) caused the Marsh to remain inundated for up to 12 months; only 25% of years (9% of all months) had floods of greater than 300 km2. The prolonged, severe and consecutive yearly inundations between 1999 and 2006 were unprecedented compared to the last century. While there is high inter-annual variability in the system, if the frequency and

  10. Potential Influence of Arctic Sea Ice to the Inter-annual Variations of East Asian Spring Precipitation

    NASA Astrophysics Data System (ADS)

    Li, Xinxin; Wu, Zhiwei; Li, Yanjie

    2016-04-01

    Arctic sea ice (ASI) and its potential climatic impacts have received increasing attention during the past decades, yet the relevant mechanisms are far from being understood, particularly on how anomalous ASI affects climate in midlatitudes. The spring precipitation takes up as much as 30% of the annual total and has significant influences to agriculture in East Asia. Here, observed evidence and numerical experiment results manifest that the ASI variability in the Norwegian Sea and the Barents Sea in preceding winter is intimately connected with interannual variations of the East Asian spring precipitation (EAP). The former can explain about 14% of the total variances of the latter. The ASI anomalies persist from winter through the ensuing spring and excite downstream tele-connections of a distinct Rossby wave train prevailing over the Eurasian continent. For the reduced ASI, such a wave train pattern is usually associated with an anomalous low pressure center over Mongolian Plateau, which accelerates the East Asian subtropical westerly jet. The intensified subtropical westerly jet, concurrent with lower-level convergence and upper-level divergence, enhances the local convection and consequently favors rich spring precipitation over East Asia. For the excessive ASI, the situation tends to be opposite. Given that seasonal prediction of the EAP remains a challenging issue, the winter ASI variability may provide another potential predictability source besides El Niño-Southern Oscillation.

  11. Study of inter-dot coupling in nano-patterned permalloy dots array

    NASA Astrophysics Data System (ADS)

    Chao, Chien-Tu; Kuo, Cheng-Yi; Tsai, Yu-Ching; Chang, C. K.; Wang, J. F.; Horng, Lance; Wu, Jong-Ching

    2011-01-01

    We present a series of studies on interdot coupling in the nanometer-scaled permalloy dots array. A standard electron beam lithography in conjunction with lift-off process was employed for patterning 30 nm thick of millions of permalloy dots array with diameter (D) of 500 nm and the aspect ratio S/D of spacing (S) to diameter ranging from 0.2 to 1.25. The magnetization reversal processes were identified to evolve through the vortex nucleation, movement, and annihilation based on magnetic force microscopy (MFM) imaging in the presence of external magnetic fields. The nucleation field, annihilation field, and moving rate of vortex core were analyzed using M-H loops measured by the alternating gradient magnetometer (AGM). These behaviors are associated with the dipole-dipole interaction in dots array with various interdot spacings.

  12. Spatiotemporal patterns enhanced by intra- and inter-molecular fluctuations in arrays of allosterically regulated enzymes

    NASA Astrophysics Data System (ADS)

    Togashi, Yuichi; Casagrande, Vanessa

    2015-03-01

    Enzymatic reactions often involve slow conformational changes, with reaction cycles that sometimes require milliseconds or seconds to complete. The dynamics are strongly affected by fluctuations at the nanoscale. However, such enzymes often occur in small numbers in a cell; hence, the fluctuations caused by finite numbers of molecules should also be substantial. Because of these factors, the behavior of the system is likely to deviate from that of classical reaction-diffusion equations, in which immediate reaction events are assumed to occur without memory and between a huge number of molecules. In this work, we model each enzyme as a unit represented by a phase variable to investigate the effects of fluctuations in arrays of enzymes. Using an analysis based on partial differential equations and stochastic simulations, we show that fluctuations arising from internal states of enzymes (intramolecular fluctuations) and those arising from the stochastic nature of interactions between molecules (intermolecular fluctuations) have distinctive effects on spatiotemporal patterns; the former generally disturb synchronization at high frequencies, whereas the latter can enhance synchronization. The balance of the two types of fluctuations may determine the spatiotemporal behavior of biochemical processes.

  13. From inter-specific behavioural interactions to species distribution patterns along gradients of habitat heterogeneity.

    PubMed

    Laiolo, Paola

    2013-01-01

    The strength of the behavioural processes associated with competitor coexistence may vary when different physical environments, and their biotic communities, come into contact, although empirical evidence of how interference varies across gradients of environmental complexity is still scarce in vertebrates. Here, I analyse how behavioural interactions and habitat selection regulate the local distribution of steppeland larks (Alaudidae) in a gradient from simple to heterogeneous agricultural landscapes in Spain, using crested lark Galerida cristata and Thekla lark G. theklae as study models. Galerida larks significantly partitioned by habitat but frequently co-occurred in heterogeneous environments. Irrespective of habitat divergence, however, the local densities of the two larks were negatively correlated, and the mechanisms beyond this pattern were investigated by means of playback experiments. When simulating the intrusion of the congener by broadcasting the species territorial calls, both larks responded with an aggressive response as intense with respect to warning and approach behaviour as when responding to the intrusion of a conspecific. However, birds promptly responded to playbacks only when congener territories were nearby, a phenomenon that points to learning as the mechanisms through which individuals finely tune their aggressive responses to the local competition levels. Heterospecifics occurred in closer proximity in diverse agro-ecosystems, possibly because of more abundant or diverse resources, and here engage in antagonistic interactions. The drop of species diversity associated with agricultural homogenisation is therefore likely to also bring about the disappearance of the behavioural repertoires associated with species interactions. PMID:22806401

  14. The Inter-annual Variability of Controlling Parameter of Catchment Water Balance and Its Semi-empirical Formula Based on the Budyko Hypotheses

    NASA Astrophysics Data System (ADS)

    Ning, T.; Liu, W.; Han, X.

    2015-12-01

    The long-term average of the controlling parameter of catchment water balance has been widely reported; however, their inter-annual variability has rarely been quantified. Besides precipitation (P) and potential evaporation(ET0), the surface condition and seasonality of climate have great impacts on inter-annual variability of catchment water balance, which can be reflected by the parameter w (in terms of Fu's equation). Two watersheds on the Loess Plateau were thus chosen to quantify their relationships. To diminish the impacts of catchment water storage on water balance, the annual water balance was firstly estimated for each water year from 1981 to 2012. Then, the annual maximum vegetation coverage (M) based on NDVI and the variation coefficient (σ) of daily wetness index (P/ET0) were used to respectively present the surface condition and the seasonal variations in the coupled water and energy, and further discuss their relationships with w. Results showed that w correlated well with M and σ, then a semi-empirical formula was developed to calculate the key parameter w on annual scale (w=1+5.99×M1.01×exp (-0.072σ), R2=0.60). The equation was further validated in some other watersheds on the Loess Plateau and proved to be superior in estimating actual evaporation (ET). Finally, the Fu's equation and the semi-empirical formula for w were combined to quantify the contributions of changes in climate (P, ET0 and σ) and surface condition (M) to ET variations. Results showed that σ and M accounted for 5.8% and -3.2% of the ET decrease for the period of 1981-1995, respectively; during 1996-2012, the contribution of σ to ET changes decreased while that of M increased by 18.9%, indicating the impacts of surface condition on catchment water balance were strengthened.

  15. Soil wetting patterns of vegetation and inter-patches following single and repeated wildfires

    NASA Astrophysics Data System (ADS)

    González, Óscar; Malvar, Maruxa; van den Elsen, Erik; Hosseini, mohammadreza; Coelho, Celeste; Ritsema, Coen; Bautista, Susana; Keizer, Jan Jacob; Cerdà, Artemi

    2015-04-01

    Although wildfires spread in Mediterranean areas are considered a natural processes, the expected increase in fire frequency has raised concerns about the systems' future resilience (Pausas, 2004). Besides more frequent, future wildfires can become more severe and produce more pronounced changes in topsoil properties, vegetation and litter (Cerdá and Mataix-Solera, 2009). To deal with challenges, the EU funded CASCADE and RECARE projects, which are currently assessing soil threats and tipping-points for land degradation in a climatic gradient across Europe. The present research was developed in Portugal and aims to find relationships between fire frequency and soil wetting patterns following single versus repeated wildfires. In September 2012, a wildfire burnt 3000 ha. of Pine stands and shrub vegetation in the vicinity of Viseu district, North-Central Portugal. Analyses according to the available burnt-area maps (1975-2012), discriminated areas that has been burned 1x (called SD) and 4x (called D) times. In order to evaluate the post-fire soil surface moisture patterns, 6 slopes (3 in SD and 3 in D) were selected and a balanced experimental design with 72 soil moisture sensors (EC5 and GS3, from Decagon devices) was implemented under shrubs (n=18) and on bare (n=18) soil environments, at 2.5 cm and 7.5 cm soil depth each. The spatio-temporal occurrence of soil water repellence (SWR) (Keizer et al., 2008; Prats et al., 2013; Santos et al., 2014) was monthly assessed through the MED test at 2.5 cm and 7.5 cm soil depth into 5 sampling points located at regular distances along a transect running from the top to bottom of a selected slope in SD and D. Automatic and totalize rainfall gauges were also installed across the study area. Preliminary results showed that soil wetting patterns and SWR occurrence differs between SD, D sites and, between soil environment (under shrubs and on bare soil areas). SWR were more pronounced on the SD than in D, affecting soil wetting

  16. Inter-nesting habitat-use patterns of loggerhead sea turtles: Enhancing satellite tracking with benthic mapping

    USGS Publications Warehouse

    Hart, Kristen M.; Zawada, David G.; Fujisaki, Ikuko; Lidz, Barbara H.

    2010-01-01

    The loggerhead sea turtle Caretta caretta faces declining nest numbers and bycatches from commercial longline fishing in the southeastern USA. Understanding spatial and temporal habitat-use patterns of these turtles, especially reproductive females in the neritic zone, is critical for guiding management decisions. To assess marine turtle habitat use within the Dry Tortugas National Park (DRTO), we used satellite telemetry to identify core-use areas for 7 loggerhead females inter-nesting and tracked in 2008 and 2009. This effort represents the first tracking of DRTO loggerheads, a distinct subpopulation that is 1 of 7 recently proposed for upgrading from threatened to endangered under the US Endangered Species Act. We also used a rapid, high-resolution, digital imaging system to map benthic habitats in turtle core-use areas (i.e. 50% kernel density zones). Loggerhead females were seasonal residents of DRTO for 19 to 51 d, and individual inter-nesting habitats were located within 1.9 km (2008) and 2.3 km (2009) of the nesting beach and tagging site. The core area common to all tagged turtles was 4.2 km2 in size and spanned a depth range of 7.6 to 11.5 m. Mapping results revealed the diversity and distributions of benthic cover available in the core-use area, as well as a heavily used corridor to/from the nesting beach. This combined tagging-mapping approach shows potential for planning and improving the effectiveness of marine protected areas and for developing spatially explicit conservation plans.

  17. A method to assess the inter-annual weather-dependent variability in air pollution concentration and deposition based on weather typing

    NASA Astrophysics Data System (ADS)

    Pleijel, Håkan; Grundström, Maria; Karlsson, Gunilla Pihl; Karlsson, Per Erik; Chen, Deliang

    2016-02-01

    Annual anomalies in air pollutant concentrations, and deposition (bulk and throughfall) of sulphate, nitrate and ammonium, in the Gothenburg region, south-west Sweden, were correlated with optimized linear combinations of the yearly frequency of Lamb Weather Types (LWTs) to determine the extent to which the year-to-year variation in pollution exposure can be partly explained by weather related variability. Air concentrations of urban NO2, CO, PM10, as well as O3 at both an urban and a rural monitoring site, and the deposition of sulphate, nitrate and ammonium for the period 1997-2010 were included in the analysis. Linear detrending of the time series was performed to estimate trend-independent anomalies. These estimated anomalies were subtracted from observed annual values. Then the statistical significance of temporal trends with and without LWT adjustment was tested. For the pollutants studied, the annual anomaly was well correlated with the annual LWT combination (R2 in the range 0.52-0.90). Some negative (annual average [NO2], ammonia bulk deposition) or positive (average urban [O3]) temporal trends became statistically significant (p < 0.05) when the LWT adjustment was applied. In all the cases but one (NH4 throughfall, for which no temporal trend existed) the significance of temporal trends became stronger with LWT adjustment. For nitrate and ammonium, the LWT based adjustment explained a larger fraction of the inter-annual variation for bulk deposition than for throughfall. This is probably linked to the longer time scale of canopy related dry deposition processes influencing throughfall being explained to a lesser extent by LWTs than the meteorological factors controlling bulk deposition. The proposed novel methodology can be used by authorities responsible for air pollution management, and by researchers studying temporal trends in pollution, to evaluate e.g. the relative importance of changes in emissions and weather variability in annual air pollution

  18. A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink

    NASA Astrophysics Data System (ADS)

    Landschützer, P.; Gruber, N.; Bakker, D. C. E.; Schuster, U.; Nakaoka, S.; Payne, M. R.; Sasse, T. P.; Zeng, J.

    2013-11-01

    , while in other regions of the North Atlantic the sea surface pCO2 increased at a slower rate, resulting in a barely changing Atlantic carbon sink north of the Equator (-0.01 ± 0.02 Pg C yr-1 decade-1). Surface ocean pCO2 increased at a slower rate relative to atmospheric CO2 over most of the Atlantic south of the Equator, leading to a substantial trend toward a stronger CO2 sink for the entire South Atlantic (-0.14 ± 0.02 Pg C yr-1 decade-1). In contrast to the 10 yr trends, the Atlantic Ocean carbon sink varies relatively little on inter-annual timescales (±0.04 Pg C yr-1; 1 σ).

  19. A neural network-based estimate of the seasonal to inter-annual variability of the Atlantic Ocean carbon sink

    NASA Astrophysics Data System (ADS)

    Landschützer, P.; Gruber, N.; Bakker, D. C. E.; Schuster, U.; Nakaoka, S.; Payne, M. R.; Sasse, T.; Zeng, J.

    2013-05-01

    equator (-0.007 Pg C yr-1 decade-1). Surface ocean pCO2 was also increasing less than that of the atmosphere over most of the Atlantic south of the equator, leading to a substantial trend toward a stronger CO2 sink for the entire South Atlantic (-0.14 Pg C yr-1 decade-1). The Atlantic carbon sink varies relatively little on inter-annual time-scales (±0.04 Pg C yr-1; 1σ).

  20. Factors Affecting the Inter-annual to Centennial Time Scale Variability of All Indian Summer Monsoon Rainfall

    NASA Astrophysics Data System (ADS)

    Malik, Abdul; Brönnimann, Stefan

    2016-04-01

    to statistically significant positive. We conclude that the positive relation between AISMR and solar activity, as found by other authors, is due to the combined effect of AMO, PDO and multi-decadal ENSO variability on AISMR. The solar activity influences the ICFs and this influence is then transmitted to AISMR. Further, we find that there is statistically positive intrinsic relation between AISMR and AMO from 26 to 100 year time scales which is modulated by ICFs (PDO, ENSO) and ECFs. PDO, ENSO, and solar activity weaken this intrinsic relationship whereas the combined effect of ECFc (solar activity, volcanic eruptions, CO2, & tropospheric aerosol optical depth) results in strengthening of this relationship from 70 to 100 year time scales. There is a negative intrinsic relation between AISMR and PDO which is not statistically significant at any time scale. However this relationship becomes statistically significant only in the presence of combined effect of North Atlantic SSTs and ENSO (4-39 year time scale) and individual effect of TSI (3-26 year time scale) on AISMR. We also find that there is statistical significant negative relationship between AISMR and ENSO on inter-annual to centennial time scale and the strength of this relationship is modulated by solar activity from 3 to 40 year time scale.

  1. The inter-annual variability of mesosphere-thermosphere nightglow intensities and their possible coupling with cosmic factors and lower atmosphere climatology

    NASA Astrophysics Data System (ADS)

    Didebulidze, Goderdzi; Todua, Maya

    2016-07-01

    Possible coupling of the inter-annual/seasonal variations of the mesosphere-thermosphere-ionosphere parameters with cosmic factors and climatology of the lower atmosphere are considered using the nightglow intensity observations from Abastumani (41.75 E; 42.82 E) of (a) the mesopause hydroxyl OH(8-3) bands (maximum luminous layer about 87 km), (b) the thermosphere oxygen green 557.7 nm line (main maximum of luminous layer in the lower thermosphere at about 95 km and small part from the ionosphere F2 region with its peak at about 230-280 km) and (c) the red 630.0 nm line (emitted from the ionosphere F2 region with maximum luminous layer about 230-280 km), which include three eleven-year solar cycles. The observed inter-annual variations of the OH bands and green line, along with their maximal values at spring (March-April) and fall (September-October) equinoxial periods, which are noticed also from other regions, exhibit additional maxima in June. The red line intensity mainly tends to decrease at equinoxial months, while it is maximal in summer and is accompanied by relatively small increase in June (compared to May and July). Maximal values of OH band and green line intensities in June are observed both in maximum and minimum phases of solar activity. This is considered as a manifestation of the features of the upper and lower atmosphere dynamical coupling of this region of Caucasus. The importance of atmospheric gravity waves and tidal motions in the observed specifics of seasonal changes of the lower and upper atmosphere-ionosphere coupling processes is indicated. The seasonal distribution tidal motions like changes of the mesopause and lower thermosphere with 6-12 hours period variations are demonstrated, which could be in situ developed and also coupled with lower atmosphere climatology. The daily mean temperature (with maximum in August) and its changes with heights (maximum in June) can influence cloud covering of this region and thus on generation of

  2. Inter-annual and seasonal trends of vegetation condition in the Upper Blue Nile (Abbay) basin: dual scale time series analysis

    NASA Astrophysics Data System (ADS)

    Teferi, E.; Uhlenbrook, S.; Bewket, W.

    2015-02-01

    A long-term decline in ecosystem functioning and productivity, often called land degradation, is a serious environmental and development challenge to Ethiopia that needs to be understood so as to develop sustainable land use strategies. This study examines inter-annual and seasonal trends of vegetation cover in the Upper Blue Nile (UBN) or Abbay basin. Advanced Very High Resolution Radiometer (AVHRR) based Global Inventory, Monitoring, and Modelling Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) was used for course scale long-term vegetation trend analysis. Moderate-resolution Imaging Spectroradiometer (MODIS) NDVI data (MOD13Q1) was used for finer scale vegetation trend analysis. Harmonic analyses and non-parametric trend tests were applied to both GIMMS NDVI (1981-2006) and MODIS NDVI (2001-2011) data sets. Based on a robust trend estimator (Theil-Sen slope) most part of the UBN (~77%) showed a positive trend in monthly GIMMS NDVI with a mean rate of 0.0015 NDVI units (3.77% yr-1), out of which 41.15% of the basin depicted significant increases (P < 0.05) with a mean rate of 0.0023 NDVI units (5.59% yr-1) during the period. However, the finer scale (250 m) MODIS-based vegetation trend analysis revealed that about 36% of the UBN shows a significantly decreasing trend (P < 0.05) over the period 2001-2011 at an average rate of 0.0768 NDVI yr-1. This indicates that the greening trend of vegetation condition was followed by browning trend since the mid-2000s in the basin, which requires the attention of land users and decision makers. Seasonal trend analysis was found to be very useful in identifying changes in vegetation condition that could be masked if only inter-annual vegetation trend analysis was performed. The finer scale intra-annual trend analysis revealed trends that were more linked to human activities. This study concludes that integrated analysis of course and fine scale, inter-annual and intra-annual trends enables a more robust

  3. Inter-annual variability of dissolved inorganic nitrogen in the Biobío River, Central Chile: an analysis base on a decadal database along with 1-D reactive transport modeling

    NASA Astrophysics Data System (ADS)

    Yévenes, M.; Figueroa, R.; Parra, O.; Farías, L.

    2015-01-01

    Rivers may act as important sinks (filters) or sources for inorganic nutrients between the land and the sea, depending on the biogeochemical processes and nutrient inputs along the river. This study examines the inter-annual variability of dissolved inorganic nitrogen (DIN) seasonal (wet-dry) cycle for the Biobío River, one of the largest and most industrialized rivers of Central Chile (36°45'-38°49' S and 71°00'-73°20' W). Long-term water flow (1990-2012) and water quality datasets (2004-2012) were used along with a one-dimensional reactive transport ecosystem model to evaluate the effects of water flow and N inputs on seasonal pattern of DIN. From 2004 to 2012, annual average nitrate levels significantly increased from 1.73 ± 2.17 μmol L-1 (upstream of the river) to 18.4 ± 12.7 μmol L-1 (in the river mouth); while the annual average oxygen concentration decreased from 348 ± 22 to 278 ± 42 μmol L-1 between upstream and downstream, indicating an additional oxygen consumption. Variability in the mid-section of the river (station BB8) was identified as a major influence on the inter-annual variability and appeared to be the site of a major anthropogenic disturbance. However, there was also an influence of climate on riverine DIN concentrations; high DIN production occurred during wet years, whereas high consumption proceeded during dry years. Extremely reduced river flow and drought during summer also strongly affected the annual DIN concentration, reducing the DIN production. Additionally, summer storm events during drought periods appeared to cause significant runoff resulting in nitrate inputs to the river. The total DIN input reaching the river mouth was 0.159 Gmol yr-1, implying that internal production exceeds consumption processes, and identifying nitrification as one of the predominant processes occurring in the estuary. In the following, the impact on the river of DIN increases as a nutrient source, as well as climate and biogeochemical factors

  4. Seasonal changes in spatial patterns of two annual plants in the Chihuahuan Desert, USA

    USGS Publications Warehouse

    Yin, Z.-Y.; Guo, Q.; Ren, H.; Peng, S.-L.

    2005-01-01

    Spatial pattern of a biotic population may change over time as its component individuals grow or die out, but whether this is the case for desert annual plants is largely unknown. Here we examined seasonal changes in spatial patterns of two annuals, Eriogonum abertianum and Haplopappus gracilis, in initial (winter) and final (summer) densities. The density was measured as the number of individuals from 384 permanent quadrats (each 0.5 m ?? 0.5 m) in the Chihuahuan Desert near Portal, Arizona, USA. We used three probability distributions (binomial, Poisson, and negative binomial or NB) that represent three basic spatial patterns (regular, random, and clumped) to fit the observed frequency distributions of densities of the two annuals. Both species showed clear clumped patterns as characterized by the NB and had similar inverse J-shaped frequency distribution curves in two density categories. Also, both species displayed a reduced degree of aggregation from winter to summer after the spring drought (massive die-off), as indicated by the increased k-parameter of the NB and decreased values of another NB parameter p, variance/mean ratio, Lloyd's Index of Patchiness, and David and Moore's Index of Clumping. Further, we hypothesized that while the NB (i.e., Poisson-logarithmic) well fits the distribution of individuals per quadrat, its components, the Poisson and logarithmic, may describe the distributions of clumps per quadrat and of individuals per clump, respectively. We thus obtained the means and variances for (1) individuals per quadrat, (2) clumps per quadrat, and (3) individuals per clump. The results showed that the decrease of the density from winter to summer for each plant resulted from the decrease of individuals per clump, rather than from the decrease of clumps per quadrat. The great similarities between the two annuals indicate that our observed temporal changes in spatial patterns may be common among desert annual plants. ?? Springer 2005.

  5. Parental Choice of Schooling, Learning Processes and Inter-Ethnic Friendship Patterns: The Case of Malay Students in Chinese Primary Schools in Malaysia

    ERIC Educational Resources Information Center

    Sua, Tan Yao; Ngah, Kamarudin; Darit, Sezali Md.

    2013-01-01

    This study surveys 200 Malay students enrolled in three Chinese primary schools in relation to three issues, i.e., parental choice of schooling, learning processes and inter-ethnic friendship patterns. The three issues are explored through a combination of quantitative and qualitative research methodologies. Parental expectations for their…

  6. Temporal and spatial variation in the Nazaré Canyon (Western Iberian margin): Inter-annual and canyon heterogeneity effects on meiofauna biomass and diversity

    NASA Astrophysics Data System (ADS)

    Ramalho, Sofia P.; Adão, Helena; Kiriakoulakis, Konstadinos; Wolff, George A.; Vanreusel, Ann; Ingels, Jeroen

    2014-01-01

    The Nazaré Canyon on the Portuguese Margin (NE Atlantic) was sampled during spring-summer for three consecutive years (2005-2007), permitting the first inter-annual study of the meiofaunal communities at the Iberian Margin at two abyssal depths (~3500 m and ~4400 m). Using new and already published data, the meiofauna standing stocks (abundance and biomass) and nematode structural and functional diversity were investigated in relation to the sediment biogeochemistry (e.g. organic carbon, nitrogen, chlorophyll a, phaeopigments) and grain size. A conspicuous increase in sand content from 2005 to 2006 and decrease of phytodetritus at both sites, suggested the occurrence of one or more physical disturbance events. Nematode standing stocks and trophic diversity decreased after these events, seemingly followed by a recovery/recolonisation period in 2007, which was strongly correlated with an increase in the quantity and bioavailability of phytodetrital organic matter supplied. Changes in meiofauna assemblages, however, also differed between stations, likely because of the contrasting hydrodynamic and food supply conditions. Higher meiofauna and nematode abundances, biomass and trophic complexity were found at the shallowest canyon station, where the quantity, quality and bioavailability of food material were higher than at the deeper site. The present results suggest that even though inter-annual variations in the sedimentary environment can regulate the meiofauna in the abyssal Nazaré Canyon, heterogeneity between sampling locations in the canyon were more pronounced.

  7. Root-associated fungi of Vaccinium carlesii in subtropical forests of China: intra- and inter-annual variability and impacts of human disturbances

    PubMed Central

    Zhang, Yanhua; Ni, Jian; Tang, Fangping; Pei, Kequan; Luo, Yiqi; Jiang, Lifen; Sun, Lifu; Liang, Yu

    2016-01-01

    Ericoid mycorrhiza (ERM) are expected to facilitate establishment of ericaceous plants in harsh habitats. However, diversity and driving factors of the root-associated fungi of ericaceous plants are poorly understood. In this study, hair-root samples of Vaccinium carlesii were taken from four forest types: old growth forests (OGF), secondary forests with once or twice cutting (SEC I and SEC II), and Cunninghamia lanceolata plantation (PLF). Fungal communities were determined using high-throughput sequencing, and impacts of human disturbances and the intra- and inter-annual variability of root-associated fungal community were evaluated. Diverse fungal taxa were observed and our results showed that (1) Intra- and inter-annual changes in root-associated fungal community were found, and the Basidiomycota to Ascomycota ratio was related to mean temperature of the sampling month; (2) Human disturbances significantly affected structure of root-associated fungal community of V. carlesii, and two secondary forest types were similar in root-associated fungal community and were closer to that of the old growth forest; (3) Plant community composition, edaphic parameters, and geographic factors significantly affected root-associated fungal communities of V. carlesii. These results may be helpful in better understanding the maintenance mechanisms of fungal diversity associated with hair roots of ERM plants under human disturbances. PMID:26928608

  8. Seasonal and inter-annual biogeochemical variations in the Porcupine Abyssal Plain 2003-2005 associated with winter mixing and surface circulation

    NASA Astrophysics Data System (ADS)

    Hartman, S. E.; Larkin, K. E.; Lampitt, R. S.; Lankhorst, M.; Hydes, D. J.

    2010-08-01

    We present a 3-year multidisciplinary biogeochemical data set taken in situ at the Porcupine Abyssal Plain (PAP) time-series observatory in the Northeast Atlantic (49°N, 16.5°W; water depth ˜4850 m) for the period 2003 to 2005. The high-resolution year-round autonomous measurements include temperature, salinity, chlorophyll-a (derived from in situ chlorophyll-fluorescence) and inorganic nitrate, all at a nominal depth of 30 m on an Eulerian observatory mooring. This study compares these in situ time-series data with satellite chlorophyll-a data, regional data from a ship of opportunity, mixed-layer depth measurements from profiling Argo floats and lateral advection estimates from altimetry. This combined and substantial data set is used to analyse seasonal and inter-annual variability in hydrography and nitrate concentrations in relation to convective mixing and lateral advection. The PAP observatory site is in the inter-gyre region of the North Atlantic where convective mixing ranges from 25 m in the summer to over 400 m in winter when nutrients are supplied to the surface. Small inter-annual changes in the winter mixed layer can result in large changes in nitrate supply and productivity. However the decrease in maximum winter nitrate over the three-year period, from 10 to 7 mmol m -3, cannot be fully explained by convective mixing. Trajectories leading to the PAP site, computed from altimetry-derived geostrophic velocities, confirm that lateral advection cannot be ignored at this site and may be an important process along with convective mixing. Over the three years, there is an associated decrease in new production calculated from nitrate assimilation from 85.4 to 40.3±4.3 gCm -2 a -1. This confirms year-to-year variability in primary production seen in model estimates for the region. The continuous in situ dataset also shows inter-annual variation in the timing of the spring bloom due to variations in heat flux; the 2005 bloom occurred earlier than in 2004.

  9. Using Ecosystem Functional Types in land-surface modeling to characterize and monitor the spatial and inter-annual variability of vegetation dynamics

    NASA Astrophysics Data System (ADS)

    Alcaraz-Segura, D.; Paruelo, J.; Epstein, H. E.; Berbery, E. H.; Kalnay, E.; Cabello, J.; Jobbagy, E. G.

    2009-12-01

    Including the inter-annual variability of vegetation dynamics into land-surface models is necessary to account for land use/cover change effects on Global Climate Models. However, land-surface models use land-cover classifications dictated by structural attributes of vegetation that have little sensitivity to environmental change and are difficult to update and result in a delayed response. This rigid representation of vegetation reduces the ability of models to represent rapid changes including land-use shifts, fires, floods, droughts, and insect outbreaks. Functional attributes of vegetation describing its energy and matter exchange with the atmosphere, have a shorter response to environmental changes and are relatively easy to monitor with satellite data. We applied the concept of Ecosystem Functional Types (EFTs; patches of the land-surface with similar carbon gain dynamics) to characterize the spatial and inter-annual variability of vegetation dynamics across natural and agricultural systems in the La Plata Basin of South America. Three descriptors of carbon gain dynamics were derived from seasonal curves of Normalized Difference Vegetation Index (NDVI) and used to identify EFTs based on annual mean (surrogate of primary production), seasonal coefficient of variation (indicator of seasonality), and date of maximum NDVI (descriptor of phenology). Results from two NDVI datasets were compared (AVHRR-LTDR version 2, 1982-1999, 15-day and 5 km resolution; and MOD13A2 MODIS, 2000-2006, 16-day and 1 km resolution). Both datasets showed greater spatial and inter-annual variability of the EFT composition in agricultural areas compared to natural areas. During 1982-1999, the percentage of the La Plata Basin occupied by EFTs with low productivity, high seasonality, and spring and fall NDVI maxima tended to decrease, while EFTs with high productivity, low seasonality, and summer maxima tended to increase. We speculate that these trends may be due to a positive trend in

  10. Inter-annual and seasonal trends of vegetation condition in the Upper Blue Nile (Abay) Basin: dual-scale time series analysis

    NASA Astrophysics Data System (ADS)

    Teferi, E.; Uhlenbrook, S.; Bewket, W.

    2015-09-01

    A long-term decline in ecosystem functioning and productivity, often called land degradation, is a serious environmental challenge to Ethiopia that needs to be understood so as to develop sustainable land use strategies. This study examines inter-annual and seasonal trends of vegetation cover in the Upper Blue Nile (UBN) or Abbay Basin. The Advanced Very High Resolution Radiometer (AVHRR)-based Global Inventory, Monitoring, and Modeling Studies (GIMMS) normalized difference vegetation index (NDVI) was used for long-term vegetation trend analysis at low spatial resolution. Moderate Resolution Imaging Spectroradiometer (MODIS) NDVI data (MOD13Q1) were used for medium-scale vegetation trend analysis. Harmonic analyses and non-parametric trend tests were applied to both GIMMS NDVI (1981-2006) and MODIS NDVI (2001-2011) data sets. Based on a robust trend estimator (Theil-Sen slope), most parts of the UBN (~ 77 %) showed a positive trend in monthly GIMMS NDVI, with a mean rate of 0.0015 NDVI units (3.77 % yr-1), out of which 41.15 % of the basin depicted significant increases (p < 0.05), with a mean rate of 0.0023 NDVI units (5.59 % yr-1) during the period. However, the MODIS-based vegetation trend analysis revealed that about 36 % of the UBN showed a significant decreasing trend (p < 0.05) over the period 2001-2011 at an average rate of 0.0768 NDVI yr-1. This indicates that the greening trend of the vegetation condition was followed by decreasing trend since the mid-2000s in the basin, which requires the attention of land users and decision makers. Seasonal trend analysis was found to be very useful to identify changes in vegetation condition that could be masked if only inter-annual vegetation trend analysis was performed. Over half (60 %) of the Abay Basin was found to exhibit significant trends in seasonality over the 25-year period (1982-2006). About 17 and 16 % of the significant trends consisted of areas experiencing a uniform increase in NDVI throughout the year

  11. Impact of intra- versus inter-annual snow depth variation on water relations and photosynthesis for two Great Basin Desert shrubs.

    PubMed

    Loik, Michael E; Griffith, Alden B; Alpert, Holly; Concilio, Amy L; Wade, Catherine E; Martinson, Sharon J

    2015-06-01

    Snowfall provides the majority of soil water in certain ecosystems of North America. We tested the hypothesis that snow depth variation affects soil water content, which in turn drives water potential (Ψ) and photosynthesis, over 10 years for two widespread shrubs of the western USA. Stem Ψ (Ψ stem) and photosynthetic gas exchange [stomatal conductance to water vapor (g s), and CO2 assimilation (A)] were measured in mid-June each year from 2004 to 2013 for Artemisia tridentata var. vaseyana (Asteraceae) and Purshia tridentata (Rosaceae). Snow fences were used to create increased or decreased snow depth plots. Snow depth on +snow plots was about twice that of ambient plots in most years, and 20 % lower on -snow plots, consistent with several down-scaled climate model projections. Maximal soil water content at 40- and 100-cm depths was correlated with February snow depth. For both species, multivariate ANOVA (MANOVA) showed that Ψ stem, g s, and A were significantly affected by intra-annual variation in snow depth. Within years, MANOVA showed that only A was significantly affected by spatial snow depth treatments for A. tridentata, and Ψ stem was significantly affected by snow depth for P. tridentata. Results show that stem water relations and photosynthetic gas exchange for these two cold desert shrub species in mid-June were more affected by inter-annual variation in snow depth by comparison to within-year spatial variation in snow depth. The results highlight the potential importance of changes in inter-annual variation in snowfall for future shrub photosynthesis in the western Great Basin Desert. PMID:25627409

  12. Climate effects on inter- and intra-annual larch stemwood anomalies in the Mongolian forest-steppe

    NASA Astrophysics Data System (ADS)

    Khishigjargal, Mookhor; Dulamsuren, Choimaa; Leuschner, Hanns Hubert; Leuschner, Christoph; Hauck, Markus

    2014-02-01

    Climate response of tree-ring width and intra-annual wood anomalies were studied in stands of Siberian larch (Larix sibirica) on Mt. Bogd Uul in the forest-steppe ecotone of Mongolia. Climate on Mt. Bogd Uul is characterized by an increase of the annual mean temperature by 1.5 K between 1965 and 2007, the lack of a long-term trend for annual precipitation and, with it, an increase in aridity. Tree-ring width increases with increasing June precipitation of the current year (June) and increasing late summer precipitation of the previous year. In >100-year old trees, also a negative correlation of tree-ring width with the July temperature of the year prior to tree-ring formation was found. Decreasing tree-ring width with increasing snowfall in December can be explained with the protection of the frost-sensitive eggs of gypsy moth by snow cover, which is a major herbivore of larch in Mongolia and causes reduction in the annual stem increment. The most significant change in wood anatomy was the decline of wide latewood, which is attributable to the increase of summer days with a mean temperature > 15 °C and drought periods in summer without precipitation. Increasing summer drought is also thought to have caused the repeated occurrence of missing rings since the 1960s, which were not observed in the late 19th and early 20th centuries.

  13. InterVA versus Spectrum: how comparable are they in estimating AIDS mortality patterns in Nairobi's informal settlements?

    PubMed Central

    Oti, Samuel Oji; Wamukoya, Marilyn; Mahy, Mary; Kyobutungi, Catherine

    2013-01-01

    Background The Spectrum computer package is used to generate national AIDS mortality estimates in settings where vital registration systems are lacking. Similarly, InterVA-4 (the latest version of the InterVA programme) is used to estimate cause-of-mortality data in countries where cause-specific mortality data are not available. Objective This study aims to compare trends in adult AIDS-related mortality estimated by Spectrum with trends from the InterVA-4 programme applied to data from a Health and Demographic Surveillance System (HDSS) in Nairobi, Kenya. Design A Spectrum model was generated for the city of Nairobi based on HIV prevalence data for Nairobi and national antiretroviral therapy coverage, underlying mortality, and migration assumptions. We then used data, generated through verbal autopsies, on 1,799 deaths that occurred in the HDSS area from 2003 to 2010 among adults aged 15–59. These data were then entered into InterVA-4 to estimate causes of death using probabilistic modelling. Estimates of AIDS-related mortality rates and all-cause mortality rates from Spectrum and InterVA-4 were compared and presented as annualised trends. Results Spectrum estimated that HIV prevalence in Nairobi was 7%, while the HDSS site measured 12% in 2010. Despite this difference, Spectrum estimated higher levels of AIDS-related mortality. Between 2003 and 2010, the proportion of AIDS-related mortality in Nairobi decreased from 63 to 40% according to Spectrum and from 25 to 16% according to InterVA. The net AIDS-related mortality in Spectrum was closer to the combined mortality rates when AIDS and tuberculosis (TB) deaths were included for InterVA-4. Conclusion Overall trends in AIDS-related deaths from both methods were similar, although the values were closer when TB deaths were included in InterVA. InterVA-4 might not accurately differentiate between TB and AIDS deaths. PMID:24160914

  14. Evaluation of spatial productivity patterns in an annual grassland during an AVIRIS overflight

    NASA Technical Reports Server (NTRS)

    Gamon, John A.; Field, Christopher B.; Ustin, Susan L.

    1992-01-01

    In May 1991, coincident with an Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) overflight, a ground-based study covering 9 hectares of an annual grassland was completed. There were two goals of this ground study: (1) obtain ecologically and physiologically meaningful data for relating AVIRIS images to canopy structure, biochemistry, and physiology; and (2) evaluate the suitability of the 20-m AVIRIS pixel size for depicting detailed spatial patterns of productivity.

  15. Inter-annual Variability of Biomass Burning Aerosol Optical Depth in Southern Amazonia, and the Impact of These Aerosols on the Diurnal Cycle of Solar Flux Reduction

    NASA Astrophysics Data System (ADS)

    Eck, T. F.; Holben, B. N.; Schafer, J. S.; Artaxo, P.; Yamasoe, M. A.; Procopio, A. S.; Prins, E. M.; Feltz, J. M.; Smirnov, A.; Dubovik, O.; Reid, J. S.

    2002-12-01

    The inter-annual variability of the magnitude of biomass burning in southern Amazonia has been relatively large over the last decade. The extent of the burning in the latter half of a given dry season (July-October) depends largely on the rainfall amount and timing, with drought years exhibiting many more fires and smoke than average. Additionally, new regulations aimed at controlling burning may also affect inter-annual variability. We present measurements of aerosol optical depth (AOD) from biomass burning smoke as measured by AERONET sites in Rondonia and Mato Grosso from 1993-2002. These AOD measurements are shown to follow similar inter-annual variability as the fire counts determined by the multi-spectral radiance measurements obtained with GOES-8. However, the AOD at these sites exhibit relatively little diurnal variation despite a very large diurnal cycle in satellite detected fire counts. In order to quantify the changes in the diurnal cycle of solar flux reduction as a result of aerosol attenuation at the peak of the burning season, we model the diurnal cycle of total shortwave (SW; 300-4000 nm), photosynthetically active radiation (PAR; 400-700 nm), and Ultraviolet- A (UVA; 320-400 nm) fluxes in mid-September using the AERONET monthly average AOD measurements (AOD(550 nm) = 1.11). These average diurnal cycle flux reductions show significant temporal delays in the morning for equivalent flux levels in all three spectral bands, of ~50 min to 2 hr 15 min at mid-morning (midpoint between sunrise and solar noon). The largest time delays in flux occur in the UVA band and the smallest in the total SW broadband due to a rapid decrease in AOD as wavelength increases for the accumulation mode smoke aerosols. The time delays in solar flux have implications for possible delay of the onset of cumulus convection, the shortening of the photo-period when plants photosynthesize, and reduced time interval for UVA fluxes which may have implications for photochemical

  16. Inter-annual variability in the thermal structure of an oceanic time series station off Ecuador (1990-2003) associated with El Niño events

    NASA Astrophysics Data System (ADS)

    Garcés-Vargas, José; Schneider, Wolfgang; Abarca del Río, Rodrigo; Martínez, Rodney; Zambrano, Eduardo

    2005-10-01

    Previously unpublished data (1990-2003) from a marine station located 20 km off the coast of Ecuador (Station La Libertad, 02°12'S, 080°55'W) are employed to investigate oceanic inter-annual variability in the far eastern equatorial Pacific, and its relation to the central-eastern equatorial Pacific. La Libertad is the only time series station between the Galapagos Islands and the South American coast, the region most affected by El Niño events (El Niño 2 region, 0-5°S, 90°W-80°W). Although configured and serviced differently, station La Libertad can be looked at as an eastern extension of the TAO/TRITON monitoring system, whose easternmost mooring is located at 95°W, 1550 km offshore. This study of El Niño's impact on the thermocline and its relationship to sea surface temperature revealed anomalies in the thermocline at station La Libertad some 2-4 months before their appearance at the sea surface. Inter-annual variability, namely quasi-biennial and quasi-quadrennial oscillations, accounts for roughly 80% of the total variance in temperature anomalies observed in the water column at station La Libertad. The coincidence in both phase and amplitude of these inter-annual oscillations explains the strength of El Niño events in the water column off La Libertad. We further show that anomalies in heat content appear 8-9 weeks earlier at 140°W in the equatorial Pacific (6550 km away from the coast) than at the coast itself. The arrival of El Niño, which has important regional social consequences as well as those for local fisheries, could therefore be predicted in the sub-surface waters off Ecuador by using these anomalies as a complementary index. In addition, the speed of the eastward propagation of these El Niño-associated anomalies' suggests the possible participation of higher-order baroclinic mode Kelvin waves and associated interaction processes in the eastern Pacific, which should be further investigated.

  17. Sensitivity of stream flow droughts, water shortage and water stress events to ENSO driven inter-annual climate variability at the global scale

    NASA Astrophysics Data System (ADS)

    Veldkamp, Ted I. E.; Aerts, Jeroen C. J. H.; Ward, Philip J.

    2014-05-01

    Governments and institutions managing water resources have to adapt constantly to regional drought, water shortage and water stress conditions, being caused by climate change, socio-economic developments and/or climate variability. Taking into account the impact of climate variability is important as in some regions it may outweigh long-term climate change or socio-economic developments, especially on a time scale of a few years up to a few decades. As governments and water management institutions apply planning horizons up to a decade with respect to management of adaptation strategies, inter-annual climate variability is especially relevant. A number of studies have estimated the impacts of climate variability on stream flow droughts on a local, continental or global scale. Others have focused on the role of long term climate change and socio-economic trends on blue water availability, shortage and stress. However, a global assessment of the influence of inter-annual climate variability on stream flow droughts, blue water availability, shortage and stress together has not yet been carried out, despite its importance for adaptation planning. To address this issue, we assessed the influence of ENSO-driven climate variability on stream flow droughts, blue water availability, and shortage and stress events at the global scale. Within this contribution we focused on El Nino Southern Oscillation's (ENSO) impact as ENSO is the most dominant source of inter-annual climate variability, impacting climate and society. We carried out this assessment through the following steps: (1) used daily discharge and run-off time-series (0.5º x 0.5º) of three WATCH forced global hydrological models (WaterGAP, PCR-GLOBWB, and STREAM); (2) in combination with time-series of population counts and monthly water demands we calculated monthly and yearly stream flow drought, water availability, water shortage and water stress per Food Producing Unit (FPU) for the period 1960-2000; and (3

  18. Differential Annual Movement Patterns in a Migratory Species: Effects of Experience and Sexual Maturation

    PubMed Central

    Jorge, Paulo E.; Sowter, David; Marques, Paulo A. M.

    2011-01-01

    Some animals migrate long distances to exploit important seasonal food resources in the northern regions of the northern hemisphere, whilst avoiding winter starvation. Changes in the individual's age and navigational skills are likely to affect migration, which in turn influences the geographic distribution of individuals. Processes such as sexual maturation and navigational abilities are affected by age, and age is thus a key factor in understanding migration patterns and differences in distribution ranges. In the present study, we investigated the effects of age on the geographic distribution of a population of Lesser Black-backed Gulls Larus fuscus throughout its annual cycle, by analyzing a dataset of 19,096 records from 10,000 color-ringed gulls. In contrast to previous assumptions, the results showed that gulls were geographically segregated by age throughout the entire annual cycle, rather than showing a geographic age-related cline only in the wintering areas. This asymmetric distribution results from a reduction in the annual range of sexually mature gulls, and the differential distribution of mature and immature individuals (mature birds remained in more northern areas, compared to immature birds, throughout the annual cycle). Furthermore, although immature gulls travelled longer distances than adults, they initiated their fall migration with short movements, in contrast to adults that migrated using longer movements. The effects identified in this study explain the non-homogenous distribution of populations throughout the annual cycle, with wide implications for the development of effective human health policies and/or wildlife management strategies. PMID:21799853

  19. The effect of inter-annual variability of consumption, production, trade and climate on crop-related green and blue water footprints and inter-regional virtual water trade: A study for China (1978-2008).

    PubMed

    Zhuo, La; Mekonnen, Mesfin M; Hoekstra, Arjen Y

    2016-05-01

    Previous studies into the relation between human consumption and indirect water resources use have unveiled the remote connections in virtual water (VW) trade networks, which show how communities externalize their water footprint (WF) to places far beyond their own region, but little has been done to understand variability in time. This study quantifies the effect of inter-annual variability of consumption, production, trade and climate on WF and VW trade, using China over the period 1978-2008 as a case study. Evapotranspiration, crop yields and green and blue WFs of crops are estimated at a 5 × 5 arc-minute resolution for 22 crops, for each year in the study period, thus accounting for climate variability. The results show that crop yield improvements during the study period helped to reduce the national average WF of crop consumption per capita by 23%, with a decreasing contribution to the total from cereals and increasing contribution from oil crops. The total consumptive WFs of national crop consumption and crop production, however, grew by 6% and 7%, respectively. By 2008, 28% of total water consumption in crop fields in China served the production of crops for export to other regions and, on average, 35% of the crop-related WF of a Chinese consumer was outside its own province. Historically, the net VW within China was from the water-rich South to the water-scarce North, but intensifying North-to-South crop trade reversed the net VW flow since 2000, which amounted 6% of North's WF of crop production in 2008. South China thus gradually became dependent on food supply from the water-scarce North. Besides, during the whole study period, China's domestic inter-regional VW flows went dominantly from areas with a relatively large to areas with a relatively small blue WF per unit of crop, which in 2008 resulted in a trade-related blue water loss of 7% of the national total blue WF of crop production. The case of China shows that domestic trade, as governed by

  20. Tropospheric ozone trends and carbon monoxide inter-annual variabilities using MOZAIC data (O3 from 1994-2007, CO from 2002-2007).

    NASA Astrophysics Data System (ADS)

    Zbinden, R. M.; Cammas, J.-P.; Thouret, V.; Nédélec, P.

    2009-04-01

    MOZAIC program (Marenco al, 1998) is performing 13 years of very accurate O3, H2O measurements and 6 years for CO with the support of airliners on commercial aircraft. Data from take off and landing for 3 clusters of airports over Germany, East of U.S.A. and Japan with more than 21000 vertical profiles all together and a 50m resolution from ground to 11 km altitude are selected to derive tropospheric ozone trends and on a shorter period carbon monoxide tropospheric inter annual variabilities. Methodology to access to tropospheric columns as defined in Zbinden et al. (2006) is improved here by taking into account an estimation of the MOZAIC unvisited tropospheric layer up when the tropopause is not reach by the aircraft during ascent or descent phase. As tropospheric ozone trend is sensitive to tropopause altitude we try to estimate its impact on tropospheric column contents. Defined as the 2pvu potential vorticity surface, we notice a tropopause general increase over the period from +140m over Germany to +680m over Japan and a winter decrease from -80 to -200m. On one hand, trends from tropospheric O3 monthly time-series are always positive for O3 in the range [+0.9, +1.1 %/year] and on the other hand CO inter-annual variabilities are always negative in the range [-2.2, -2.8%/year]. Discussion about stratospheric intrusion contents as pure tropospheric air mass will be excluded from this presentation. Seasonal aspect of O3 tropospheric trends exhibits a winter-spring major increase [+0.7, +1.5 %/year] and a minor summer-fall increase [0,+0.8 %/year]. CO inter-annual variabilities seem highly decreasing during summer-fall [-4.5, -1.5 %/year] and during winter-spring inter-annual variabilities is found a minor lessening is in the range [0, -2.6%/year]. Contribution of boundary layer, mid-troposphere and upper-troposphere to the tropospheric trends will be detailed. We will also underline the influence of the observational time with a special focus on Germany, most

  1. Inter- and intra-annual variation of water footprint of crops and blue water scarcity in the Yellow River basin (1961-2009)

    NASA Astrophysics Data System (ADS)

    Zhuo, La; Mekonnen, Mesfin M.; Hoekstra, Arjen Y.; Wada, Yoshihide

    2016-01-01

    The Yellow River Basin (YRB), the second largest river basin of China, has experienced a booming agriculture over the past decades. But data on variability of and trends in water consumption, pollution and scarcity in the YRB are lacking. We estimate, for the first time, the inter- and intra-annual water footprint (WF) of crop production in the YRB for the period 1961-2009 and the variation of monthly scarcity of blue water (ground and surface water) for 1978-2009, by comparing the blue WF of agriculture, industry and households in the basin to the maximum sustainable level. Results show that the average overall green (from rainfall) and blue (from irrigation) WFs of crops in the period 2001-2009 were 14% and 37% larger, respectively, than in the period 1961-1970. The annual nitrogen- and phosphorus-related grey WFs (water required to assimilate pollutants) of crop production grew by factors of 24 and 36, respectively. The green-blue WF per ton of crop reduced significantly due to improved crop yields, while the grey WF increased because of the growing application of fertilizers. The ratio of blue to green WF increased during the study period resulting from the expansion of irrigated agriculture. In the period 1978-2009, the annual total blue WFs related to agriculture, industry and households varied between 19% and 52% of the basin's natural runoff. The blue WF in the YRB generally peaks around May-July, two months earlier than natural peak runoff. On average, the YRB faced moderate to severe blue water scarcity during seven months (January-July) per year. Even in the wettest month in a wet year, about half of the area of the YRB still suffered severe blue water scarcity, especially in the basin's northern part.

  2. Sea level anomaly on the Patagonian continental shelf: Trends, annual patterns and geostrophic flows

    NASA Astrophysics Data System (ADS)

    Ruiz Etcheverry, L. A.; Saraceno, M.; Piola, A. R.; Strub, P. T.

    2016-04-01

    We study the annual patterns and linear trend of satellite sea level anomaly (SLA) over the southwest South Atlantic continental shelf (SWACS) between 54ºS and 36ºS. Results show that south of 42°S the thermal steric effect explains nearly 100% of the annual amplitude of the SLA, while north of 42°S it explains less than 60%. This difference is due to the halosteric contribution. The annual wind variability plays a minor role over the whole continental shelf. The temporal linear trend in SLA ranges between 1 and 5 mm/yr (95% confidence level). The largest linear trends are found north of 39°S, at 42°S and at 50°S. We propose that in the northern region the large positive linear trends are associated with local changes in the density field caused by advective effects in response to a southward displacement of the South Atlantic High. The causes of the relative large SLA trends in two southern coastal regions are discussed as a function meridional wind stress and river discharge. Finally, we combined the annual cycle of SLA with the mean dynamic topography to estimate the absolute geostrophic velocities. This approach provides the first comprehensive description of the seasonal component of SWACS circulation based on satellite observations. The general circulation of the SWACS is northeastward with stronger/weaker geostrophic currents in austral summer/winter. At all latitudes, geostrophic velocities are larger (up to 20 cm/s) close to the shelf-break and decrease toward the coast. This spatio-temporal pattern is more intense north of 45°S.

  3. Establishment of woody riparian vegetation in relation to annual patterns of streamflow, Bill Williams River, Arizona

    USGS Publications Warehouse

    Shafroth, P.B.; Auble, G.T.; Stromberg, J.C.; Patten, D.T.

    1998-01-01

    Previous studies have revealed the close coupling of components of annual streamflow hydrographs and the germination and establishment of Populus species. Key hydrograph components include the timing and magnitude of flood peaks, the rate of decline of the recession limb, and the magnitude of base flows. In this paper, we retrospectively examine establishment of four woody riparian species along the Bill Williams River, Arizona, USA, in the context of annual patterns of streamflow for the years 1993-1995. The four species examined were the native Populus fremontii, Salix gooddingii, and Baccharis salicifolia and the exotic Tamarix ramosissima. We modeled locations suitable for germination of each species along eight study transects by combining historic discharge data, calculated stage-discharge relationships, and seed-dispersal timing observations. This germination model was a highly significant predictor of seedling establishment. Where germination was predicted to occur, we compared values of several environmental variables in quadrats where we observed successful establishment with quadrats where establishment was unsuccessful. The basal area of mature woody vegetation, the maximum annual depth to ground water, and the maximum rate of water-table decline were the variables that best discriminated between quadrats with and without seedlings. The results of this study suggest that the basic components of models that relate establishment of Populus spp. to annual patterns of streamflow may also be applicable to other woody riparian species. Reach-to-reach variation in stage-discharge relationships can influence model parameters, however, and should be considered if results such as ours are to be used in efforts to prescribe reservoir releases to promote establishment of native riparian vegetation.

  4. Inter-annual rainfall variability in the eastern Antilles and coupling with the regional and intra-seasonal circulation

    NASA Astrophysics Data System (ADS)

    Jury, Mark R.

    2015-08-01

    Climate variability in the eastern Antilles island chain is analyzed via principal component analysis of high-resolution monthly rainfall in the period 1981-2013. The second mode reflecting higher rainfall in July-October season between Martinique and Grenada is the focus of this study. Higher rainfall corresponds with a weakened trade wind and boundary current along the southern edge of the Caribbean. This quells the coastal upwelling off Venezuela and builds the freshwater plume east of Trinidad. There is corresponding upper easterly wind flow that intensifies passing tropical waves. During a storm event over the Antilles on 4-5 October 2010, there was inflow from east of Guyana where low salinity and high sea temperatures enable surplus latent heat fluxes. A N-S convective rain band forms ˜500 km east of the cyclonic vortex. Many features at the weather timescale reflect the seasonal correlation and composite difference maps and El Nino Southern Oscillation (ENSO) modulation of oceanic inter-basin transfers.

  5. Intra- and Inter-Individual Variation in Self-Reported Code-Switching Patterns of Adult Multilinguals

    ERIC Educational Resources Information Center

    Dewaele, Jean-Marc; Li, Wei

    2014-01-01

    The present study is a large-scale quantitative analysis of intra-individual variation (linked to type of interlocutor) and inter-individual variation (linked to multilingualism, sociobiographical variables and three personality traits) in self-reported frequency of code-switching (CS) among 2116 multilinguals. We found a significant effect of…

  6. A Nonstationary Hidden Markov Model for Stochastic Streamflow Simulation and Inter-annual Forecasting in the Upper Colorado River Basin

    NASA Astrophysics Data System (ADS)

    Bracken, C. W.; Rajagopalan, B.; Zagona, E. A.

    2011-12-01

    Upper Colorado River Basin annual flow exhibits very low autocorrelation but regime shifting behavior causing long departures from the historical average flow producing sustained wet and dry periods. Traditional stochastic time series models do not capture this feature thereby misleading the water resources system risk and consequently impacting the management and planning efforts. To address this, we developed a nonstationary Hidden Markov (HM) model with Gamma component distributions, as opposed to Normal distributions which is widely used in literature, for stochastic simulation and short term forecasting. Global decoding from this model reveals and captures strong underlying persistent structure in the Lees Ferry flow time series. In addition to capturing the shifting mean, simulations from this model have a 20% greater chance than a first order Auto Regressive model (AR1), the best time series model for this data, of simulating wet and dry runs of 6 or more years. Relative to AR1 the HM model also captures the spectral features quite well. When applied to short term forecasting (i.e. of 1-2 years) they show higher skill relative to climatology but also to an AR1 model.

  7. The seasonal and inter-annual variability of sea-ice, ocean circulation and marine ecosystems in the Barents Sea: model results against satellite data

    NASA Astrophysics Data System (ADS)

    Dvornikov, Anton; Sein, Dmitry; Ryabchenko, Vladimir; Gorchakov, Victor; Pugalova, Svetlana

    2015-04-01

    This study is aimed at modelling the seasonal and inter-annual variability of sea-ice, ocean circulation and marine ecosystems in the Barents Sea in the modern period. Adequate description of marine ecosystems in the ice-covered seas crucially depends on the accuracy in determining of thicknesses of ice and snow on the sea surface which control penetrating photosynthetically active radiation under the ice. One of the few models of ice able to adequately reproduce the dynamics of sea ice is the sea ice model HELMI [1], containing 7 different categories of ice. This model has been imbedded into the Princeton Ocean Model. With this coupled model 2 runs for the period 1998-2007 were performed under different atmospheric forcing prescribed from NCEP/NCAR and ERA-40 archives. For prescribing conditions at the open boundary, all the necessary information about the horizontal velocity, level, temperature and salinity of the water, ice thickness and compactness was taken from the results of the global ocean general circulation model of the Max Planck Institute for Meteorology (Hamburg, Germany) MPIOM [2]. The resulting solution with NCEP forcing with a high accuracy simulates the seasonal and inter-annual variability of sea surface temperature (SST) estimated from MODIS data. The maximum difference between the calculated and satellite-derived SSTs (averaged over 4 selected areas of the Barents Sea) during the period 2000-2007 does not exceed 1.5 °C. Seasonal and inter-annual variations in the area of ice cover are also in good agreement with satellite-derived estimates. Pelagic ecosystem model developed in [3] has been coupled into the above hydrodynamic model and used to calculate the changes in the characteristics of marine ecosystems under NCEP forcing. Preliminarily the ecosystem model has been improved by introducing a parameterization of detritus deposition on the bottom and through the selection of optimal parameters for photosynthesis and zooplankton grazing

  8. Inter- and intra-annual variability of fluvial sediment transport in the proglacial river Riffler Bach (Weißseeferner, Ötztal Alps, Tyrol)

    NASA Astrophysics Data System (ADS)

    Baewert, Henning; Weber, Martin; Morche, David

    2015-04-01

    The hydrology of a proglacial river is strongly affected by glacier melting. Due to glacier retreat the effects of snow melt and rain storms will become more important in future decades. Additionally, the development of periglacial landscapes will play a more important role in the hydrology of proglacial rivers. The importance of paraglacial sediment sources in sediment budgets of glacier forefields is increasing, while the role of glacial erosion is declining. In two consecutive ablation seasons the fluvial sediment transport of the river Riffler Bach in the Kaunertal (Tyrol/Austria) was quantified. The catchment area of this station is 20 km² with an altitudinal range from 1929 m to 3518 m above msl. The "Weißseeferner" glacier (2.34 km² in 2012) is the greatest of the remaining glaciers. An automatic water sampler (AWS 2002) and a probe for water level were installed were installed at the outlet of the catchment. In order to calculate annual stage-discharge-relations, discharge (Q) was repeatedly measured with current meters. Concurrent to the discharge measurements bed load was collected using a portable Helley-Smith sampler. Bed load (BL) samples were weighted and sieved in the laboratory to gain annual bed load rating curves and grain size distributions. In 2012, 154 water samples were sampled during 7 periods and subsequently filtered to quantify suspended sediment concentrations (SSC). A Q-SSC-relation was calculated for every period due to the high variability in suspended sediment transport. In addition, the grain size distribution of the filtered material was determined by laser diffraction analysis. In 2013, the same procedure was performed for 232 water samples which were collected during 9 periods. Meteorological data were logged at the climate station "Weißsee", which is located in the centre of the study area. First results show a high variability of discharge and solid sediment transport both at the inter-annual as well as at the intra-annual

  9. Diversity in plant hydraulic traits explains seasonal and inter-annual variations of vegetation dynamics in seasonally dry tropical forests.

    PubMed

    Xu, Xiangtao; Medvigy, David; Powers, Jennifer S; Becknell, Justin M; Guan, Kaiyu

    2016-10-01

    We assessed whether diversity in plant hydraulic traits can explain the observed diversity in plant responses to water stress in seasonally dry tropical forests (SDTFs). The Ecosystem Demography model 2 (ED2) was updated with a trait-driven mechanistic plant hydraulic module, as well as novel drought-phenology and plant water stress schemes. Four plant functional types were parameterized on the basis of meta-analysis of plant hydraulic traits. Simulations from both the original and the updated ED2 were evaluated against 5 yr of field data from a Costa Rican SDTF site and remote-sensing data over Central America. The updated model generated realistic plant hydraulic dynamics, such as leaf water potential and stem sap flow. Compared with the original ED2, predictions from our novel trait-driven model matched better with observed growth, phenology and their variations among functional groups. Most notably, the original ED2 produced unrealistically small leaf area index (LAI) and underestimated cumulative leaf litter. Both of these biases were corrected by the updated model. The updated model was also better able to simulate spatial patterns of LAI dynamics in Central America. Plant hydraulic traits are intercorrelated in SDTFs. Mechanistic incorporation of plant hydraulic traits is necessary for the simulation of spatiotemporal patterns of vegetation dynamics in SDTFs in vegetation models. PMID:27189787

  10. Biogeochemical variations at the Porcupine Abyssal Plain sustained Observatory in the northeast Atlantic Ocean, from weekly to inter-annual timescales

    NASA Astrophysics Data System (ADS)

    Hartman, S. E.; Jiang, Z.-P.; Turk, D.; Lampitt, R. S.; Frigstad, H.; Ostle, C.; Schuster, U.

    2015-02-01

    We present high-resolution autonomous measurements of carbon dioxide partial pressure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained Observatory (PAP-SO) in the northeast Atlantic (49° N, 16.5° W; water depth of 4850 m) for the period 2010-2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under-saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier data set collected at the site (2003-2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of deep winter mixing and the intensity of the spring bloom. The 2010-2012 period shows an overall increase in p(CO2) values when compared to the 2003-2005 period as would be expected from increases due to anthropogenic CO2 emissions. The surface temperature, wind speed and MLD measurements are similar for both periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy.

  11. Biogeochemical variations at the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) in the northeast Atlantic Ocean, from weekly to inter-annual time scales

    NASA Astrophysics Data System (ADS)

    Hartman, Susan; Lampitt, Richard

    2015-04-01

    We present high-resolution autonomous measurements of carbon dioxide partial pres- sure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained observatory (PAP- SO) in the northeast Atlantic (49N, 16.5W; water depth of 4850 m) for the period 2010 to 2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a-fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time-series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier dataset collected at the site (2003 to 2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of deep winter mixing and the intensity of the spring bloom. The 2010-2012 period shows an overall increase in p(CO2) values when compared to the 2003-2005 period as would be expected from increases due to anthropogenic CO2 emissions. The surface temperature, wind speed and MLD measurements are similar for both periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy.

  12. Biogeochemical variations at the Porcupine Abyssal Plain Sustained Observatory (PAP-SO) in the northeast Atlantic Ocean, from weekly to inter-annual time scales

    NASA Astrophysics Data System (ADS)

    Hartman, S. E.; Jiang, Z.-P.; Turk, D.; Lampitt, R. S.; Frigstad, H.; Ostle, C.

    2014-08-01

    We present high-resolution autonomous measurements of carbon dioxide partial pressure p(CO2) taken in situ at the Porcupine Abyssal Plain sustained observatory (PAP-SO) in the Northeast Atlantic (49° N, 16.5° W; water depth of 4850 m) for the period 2010 to 2012. Measurements of p(CO2) made at 30 m depth on a sensor frame are compared with other autonomous biogeochemical measurements at that depth (including chlorophyll a-fluorescence and nitrate concentration data) to analyse weekly to seasonal controls on p(CO2) flux in the inter-gyre region of the North Atlantic. Comparisons are also made with in situ regional time-series data from a ship of opportunity and mixed layer depth (MLD) measurements from profiling Argo floats. There is a persistent under saturation of CO2 in surface waters throughout the year which gives rise to a perennial CO2 sink. Comparison with an earlier dataset collected at the site (2003 to 2005) confirms seasonal and inter-annual changes in surface seawater chemistry. There is year-to-year variability in the timing of stratification and deep winter mixing. The 2010 to 2012 period shows an overall increase in p(CO2) values when compared to the 2003-2005 period. This is despite similar surface temperature, wind speed and MLD measurements between the two periods of time. Future work should incorporate daily CO2 flux measurements made using CO2 sensors at 1 m depth and the in situ wind speed data now available from the UK Met Office Buoy.

  13. Inter-annual Tropospheric Aerosol Variability in Late Twentieth Century and its Impact on Tropical Atlantic and West African Climate by Direct and Semi-direct Effects

    SciTech Connect

    Evans, Katherine J; Hack, James J; Truesdale, John; Mahajan, Salil; Lamarque, J-F

    2012-01-01

    A new high-resolution (0.9$^{\\circ}$x1.25$^{\\circ}$ in the horizontal) global tropospheric aerosol dataset with monthly resolution is generated using the finite-volume configuration of Community Atmosphere Model (CAM4) coupled to a bulk aerosol model and forced with recent estimates of surface emissions for the latter part of twentieth century. The surface emissions dataset is constructed from Coupled Model Inter-comparison Project (CMIP5) decadal-resolution surface emissions dataset to include REanalysis of TROpospheric chemical composition (RETRO) wildfire monthly emissions dataset. Experiments forced with the new tropospheric aerosol dataset and conducted using the spectral configuration of CAM4 with a T85 truncation (1.4$^{\\circ}$x1.4$^{\\circ}$) with prescribed twentieth century observed sea surface temperature, sea-ice and greenhouse gases reveal that variations in tropospheric aerosol levels can induce significant regional climate variability on the inter-annual timescales. Regression analyses over tropical Atlantic and Africa reveal that increasing dust aerosols can cool the North African landmass and shift convection southwards from West Africa into the Gulf of Guinea in the spring season in the simulations. Further, we find that increasing carbonaceous aerosols emanating from the southwestern African savannas can cool the region significantly and increase the marine stratocumulus cloud cover over the southeast tropical Atlantic ocean by aerosol-induced diabatic heating of the free troposphere above the low clouds. Experiments conducted with CAM4 coupled to a slab ocean model suggest that present day aerosols can shift the ITCZ southwards over the tropical Atlantic and can reduce the ocean mixed layer temperature beneath the increased marine stratocumulus clouds in the southeastern tropical Atlantic.

  14. The dynamics of avian influenza in Lesser Snow Geese: implications for annual and migratory infection patterns.

    PubMed

    Samuel, Michael D; Hall, Jeffrey S; Brown, Justin D; Goldberg, Diana R; Ip, Hon; Baranyuk, Vasily V

    2015-10-01

    Wild water birds are the natural reservoir for low-pathogenic avian influenza viruses (AIV). However, our ability to investigate the epizootiology of AIV in these migratory populations is challenging and, despite intensive worldwide surveillance, remains poorly understood. We conducted a cross-sectional, retrospective analysis in Pacific Flyway Lesser Snow Geese, Chen caerulescens, to investigate AIV serology and infection patterns. We collected nearly 3000 sera samples from Snow Geese at two breeding colonies in Russia and Canada during 1993-1996 and swab samples from >4000 birds at wintering and migration areas in the United States during 2006-2011. We found seroprevalence and annual seroconversion varied considerably among years. Seroconversion and infection rates also differed between Snow Goose breeding colonies and wintering areas, suggesting that AIV exposure in this gregarious waterfowl species is likely occurring during several phases (migration, wintering, and potentially breeding areas) of the annual cycle. We estimated AIV antibody persistence was longer (14 months) in female geese compared to males (6 months). This relatively long period of AIV antibody persistence suggests that subtype-specific serology may be an effective tool for detection of exposure to subtypes associated with highly pathogenic AIV. Our study provides further evidence of high seroprevalence in Arctic goose populations, and estimates of annual AIV seroconversion and antibody persistence for North American waterfowl. We suggest future AIV studies include serology to help elucidate the epizootiological dynamics of AIV in wild bird populations. PMID:26591451

  15. The Influences of Drought and Land-Cover Conversion on Inter-Annual Variation of NPP in the Three-North Shelterbelt Program Zone of China Based on MODIS Data

    PubMed Central

    Wu, Chaoyang; Zhang, Bing; Huete, Alfredo; Zhang, Xiaoyang; Sun, Rui; Lei, Liping; Huang, Wenjing; Liu, Liangyun; Liu, Xinjie; Li, Jun; Luo, Shezhou; Fang, Bin

    2016-01-01

    Terrestrial ecosystems greatly contribute to carbon (C) emission reduction targets through photosynthetic C uptake.Net primary production (NPP) represents the amount of atmospheric C fixed by plants and accumulated as biomass. The Three-North Shelterbelt Program (TNSP) zone accounts for more than 40% of China’s landmass. This zone has been the scene of several large-scale ecological restoration efforts since the late 1990s, and has witnessed significant changes in climate and human activities.Assessing the relative roles of different causal factors on NPP variability in TNSP zone is very important for establishing reasonable local policies to realize the emission reduction targets for central government. In this study, we examined the relative roles of drought and land cover conversion(LCC) on inter-annual changes of TNSP zone for 2001–2010. We applied integrated correlation and decomposition analyses to a Standardized Evapotranspiration Index (SPEI) and MODIS land cover dataset. Our results show that the 10-year average NPP within this region was about 420 Tg C. We found that about 60% of total annual NPP over the study area was significantly correlated with SPEI (p<0.05). The LCC-NPP relationship, which is especially evident for forests in the south-central area, indicates that ecological programs have a positive impact on C sequestration in the TNSP zone. Decomposition analysis generally indicated that the contributions of LCC, drought, and other Natural or Anthropogenic activities (ONA) to changes in NPP generally had a consistent distribution pattern for consecutive years. Drought and ONA contributed about 74% and 23% to the total changes in NPP, respectively, and the remaining 3% was attributed to LCC. Our results highlight the importance of rainfall supply on NPP variability in the TNSP zone. PMID:27348303

  16. The Influences of Drought and Land-Cover Conversion on Inter-Annual Variation of NPP in the Three-North Shelterbelt Program Zone of China Based on MODIS Data.

    PubMed

    Peng, Dailiang; Wu, Chaoyang; Zhang, Bing; Huete, Alfredo; Zhang, Xiaoyang; Sun, Rui; Lei, Liping; Huang, Wenjing; Liu, Liangyun; Liu, Xinjie; Li, Jun; Luo, Shezhou; Fang, Bin

    2016-01-01

    Terrestrial ecosystems greatly contribute to carbon (C) emission reduction targets through photosynthetic C uptake.Net primary production (NPP) represents the amount of atmospheric C fixed by plants and accumulated as biomass. The Three-North Shelterbelt Program (TNSP) zone accounts for more than 40% of China's landmass. This zone has been the scene of several large-scale ecological restoration efforts since the late 1990s, and has witnessed significant changes in climate and human activities.Assessing the relative roles of different causal factors on NPP variability in TNSP zone is very important for establishing reasonable local policies to realize the emission reduction targets for central government. In this study, we examined the relative roles of drought and land cover conversion(LCC) on inter-annual changes of TNSP zone for 2001-2010. We applied integrated correlation and decomposition analyses to a Standardized Evapotranspiration Index (SPEI) and MODIS land cover dataset. Our results show that the 10-year average NPP within this region was about 420 Tg C. We found that about 60% of total annual NPP over the study area was significantly correlated with SPEI (p<0.05). The LCC-NPP relationship, which is especially evident for forests in the south-central area, indicates that ecological programs have a positive impact on C sequestration in the TNSP zone. Decomposition analysis generally indicated that the contributions of LCC, drought, and other Natural or Anthropogenic activities (ONA) to changes in NPP generally had a consistent distribution pattern for consecutive years. Drought and ONA contributed about 74% and 23% to the total changes in NPP, respectively, and the remaining 3% was attributed to LCC. Our results highlight the importance of rainfall supply on NPP variability in the TNSP zone. PMID:27348303

  17. Numerical simulation of inter-annual variations in the properties of the upper mixed layer in the Black Sea over the last 34 years

    NASA Astrophysics Data System (ADS)

    Shapiro, Georgy I.; Wobus, Fred; Zatsepin, Andrei G.; Akivis, Tatiana M.; Zanacchi, Marcus; Stanichny, Sergey

    2014-05-01

    The Black Sea is a nearly land-locked basin where a combination of salt and heat budgets results in a unique thermohaline water mass structure. An important feature of the Black Sea is that oxygen is dissolved and rich sea life made possible only in the upper water levels. This is due to a strong pycnocline which cannot be mixed even by strong winds or winter convection (Shapiro, 2008). The upper mixed layer (UML) with a nearly uniform temperature profile and a very sharp seasonal thermocline at its lower boundary develops during the summer season (Sur & Ilyin, 1997). The deepening of the UML has an important effect on the supply of nutrients into the euphotic upper layer from the underlying nutrient-rich water mass. The temperature of the UML at any given location is dependent on the surface heat flux, horizontal advection of heat, the depth and the rate of deepening of the UML. In this study we use a 3D ocean circulation model, NEMO-SHELF (O'Dea et al, 2012) to simulate the parameters of the UML in the Black Sea over the last 34 years. The model has horizontal resolution of 1/12×1/16 degrees and 33 layers in the vertical. The vertical discretization uses a hybrid enveloped s-z grid developed in Shapiro et al. (2012). The model is spun up from climatology (Suvorov et al., 2004); it is forced by the Drakkar Forcing Set v5.2 (Brodeau et al., 2010, Meinvielle et al., 2013) and river discharges from 8 major rivers are included. For each year the model is run from 1st January and the data for the period April to October are used for analysis. The sea surface temperature produced by the model is compared with satellite data ( Modis-Aqua, 2013) to show a good agreement. The model simulations are validated against in-situ observations (BSERP-3, 2004; Piotukh et al., 2011). The analysis is performed for the deep basin where the depth of the sea is greater than 1000m. It clearly shows the inter-annual variations of both the SST and the depth of UML. The depth of UML is

  18. Evaluating the effects of China's pollution controls on inter-annual trends and uncertainties of atmospheric mercury emissions

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhong, H.; Zhang, J.; Nielsen, C. P.

    2015-04-01

    China's anthropogenic emissions of atmospheric mercury (Hg) are effectively constrained by national air pollution control and energy efficiency policies. In this study, improved methods, based on available data from domestic field measurements, are developed to quantify the benefits of Hg abatement by various emission control measures. Those measures include increased use of (1) flue gas desulfurization (FGD) and selective catalyst reduction (SCR) systems in power generation; (2) precalciner kilns with fabric filters (FF) in cement production; (3) mechanized coking ovens with electrostatic precipitators (ESP) in iron and steel production; and (4) advanced production technologies in nonferrous metal smelting. Investigation reveals declining trends in emission factors for each of these sources, which together drive a much slower growth of total Hg emissions than the growth of China's energy consumption and economy, from 679 metric tons (t) in 2005 to 750 t in 2012. In particular, estimated emissions from the above-mentioned four source types declined 3% from 2005 to 2012, which can be attributed to expanded deployment of technologies with higher energy efficiencies and air pollutant removal rates. Emissions from other anthropogenic sources are estimated to increase by 22% during the period. The species shares of total Hg emissions have been stable in recent years, with mass fractions of around 55, 39, and 6% for gaseous elemental Hg (Hg0), reactive gaseous mercury (Hg2+), and particle-bound mercury (Hgp), respectively. The higher estimate of total Hg emissions than previous inventories is supported by limited simulation of atmospheric chemistry and transport. With improved implementation of emission controls and energy saving, a 23% reduction in annual Hg emissions from 2012 to 2030, to below 600 t, is expected at the most. While growth in Hg emissions has been gradually constrained, uncertainties quantified by Monte Carlo simulation for recent years have increased

  19. Influence of seasonal and inter-annual hydro-meteorological variability on surface water fecal coliform concentration under varying land-use composition.

    PubMed

    St Laurent, Jacques; Mazumder, Asit

    2014-01-01

    Quantifying the influence of hydro-meteorological variability on surface source water fecal contamination is critical to the maintenance of safe drinking water. Historically, this has not been possible due to the scarcity of data on fecal indicator bacteria (FIB). We examined the relationship between hydro-meteorological variability and the most commonly measured FIB, fecal coliform (FC), concentration for 43 surface water sites within the hydro-climatologically complex region of British Columbia. The strength of relationship was highly variable among sites, but tended to be stronger in catchments with nival (snowmelt-dominated) hydro-meteorological regimes and greater land-use impacts. We observed positive relationships between inter-annual FC concentration and hydro-meteorological variability for around 50% of the 19 sites examined. These sites are likely to experience increased fecal contamination due to the projected intensification of the hydrological cycle. Seasonal FC concentration variability appeared to be driven by snowmelt and rainfall-induced runoff for around 30% of the 43 sites examined. Earlier snowmelt in nival catchments may advance the timing of peak contamination, and the projected decrease in annual snow-to-precipitation ratio is likely to increase fecal contamination levels during summer, fall, and winter among these sites. Safeguarding drinking water quality in the face of such impacts will require increased monitoring of FIB and waterborne pathogens, especially during periods of high hydro-meteorological variability. This data can then be used to develop predictive models, inform source water protection measures, and improve drinking water treatment. PMID:24095594

  20. Seasonal and inter-annual variability of bud development as related to climate in two coexisting Mediterranean Quercus species

    PubMed Central

    Alla, Arben Q.; Camarero, J. Julio; Montserrat-Martí, Gabriel

    2013-01-01

    Background and Aims In trees, bud development is driven by endogenous and exogenous factors such as species and climate, respectively. However, knowledge is scarce on how these factors drive changes in bud size across different time scales. Methods The seasonal patterns of apical bud enlargement are related to primary and secondary growth in two coexisting Mediterranean oaks with contrasting leaf habit (Quercus ilex, evergreen; Quercus faginea, deciduous) over three years. In addition, the climatic factors driving changes in bud size of the two oak species were determined by correlating bud mass with climatic variables at different time scales (from 5 to 30 d) over a 15-year period. Key Results The maximum enlargement rate of buds was reached between late July and mid-August in both species. Moreover, apical bud size increased with minimum air temperatures during the period of maximum bud enlargement rates. Conclusions The forecasted rising minimum air temperatures predicted by climatic models may affect bud size and consequently alter crown architecture differentially in sympatric Mediterranean oaks. However, the involvement of several drivers controlling the final size of buds makes it difficult to predict the changes in bud size as related to ongoing climate warming. PMID:23179859

  1. Scavengers on the Move: Behavioural Changes in Foraging Search Patterns during the Annual Cycle

    PubMed Central

    López-López, Pascual; Benavent-Corai, José; García-Ripollés, Clara; Urios, Vicente

    2013-01-01

    Background Optimal foraging theory predicts that animals will tend to maximize foraging success by optimizing search strategies. However, how organisms detect sparsely distributed food resources remains an open question. When targets are sparse and unpredictably distributed, a Lévy strategy should maximize foraging success. By contrast, when resources are abundant and regularly distributed, simple Brownian random movement should be sufficient. Although very different groups of organisms exhibit Lévy motion, the shift from a Lévy to a Brownian search strategy has been suggested to depend on internal and external factors such as sex, prey density, or environmental context. However, animal response at the individual level has received little attention. Methodology/Principal Findings We used GPS satellite-telemetry data of Egyptian vultures Neophron percnopterus to examine movement patterns at the individual level during consecutive years, with particular interest in the variations in foraging search patterns during the different periods of the annual cycle (i.e. breeding vs. non-breeding). Our results show that vultures followed a Brownian search strategy in their wintering sojourn in Africa, whereas they exhibited a more complex foraging search pattern at breeding grounds in Europe, including Lévy motion. Interestingly, our results showed that individuals shifted between search strategies within the same period of the annual cycle in successive years. Conclusions/Significance Results could be primarily explained by the different environmental conditions in which foraging activities occur. However, the high degree of behavioural flexibility exhibited during the breeding period in contrast to the non-breeding period is challenging, suggesting that not only environmental conditions explain individuals' behaviour but also individuals' cognitive abilities (e.g., memory effects) could play an important role. Our results support the growing awareness about the role of

  2. Prediction of Seasonal to Inter-annual Hydro-climatology including the Effects of Vegetation Dynamics and Topography over Large River Basins

    NASA Astrophysics Data System (ADS)

    Bisht, G.; Narayan, U.; Bras, R. L.

    2008-12-01

    The goal of the proposed research is to enhance the predictability of hydrology and atmospheric conditions at daily, seasonal and inter-annual time scales. Capturing the interplay between seasonally dynamic vegetation and topography occurring through the local mechanisms of radiation and soil moisture re- distribution may contribute significantly towards increasing hydro-climatological predictability at fine spatio- temporal scales. We present a coupled model that improves the representation of vegetation dynamics with complex topography using the TIN (Triangulated Irregular Network)-based Real-time Integrated Basin Simulator (tRIBS) coupled with an advanced regional atmospheric model (WRF, Weather Research Forecasting). The tRIBS-WRF coupled model has been implemented in a parallel computing framework to allow fine scale simulations over large spatial domains for multi year time periods. The simulations have been carried out for a multi year period and we analyze the accuracy of predicted hydro-climatological variables such as monthly precipitation accumulation, soil moisture and vegetation (LAI, phenology) for different cases of (i) flat topography, prescribed vegetation (ii) real topography, prescribed vegetation (iii) flat topography, dynamic vegetation and (iv) real topography, dynamic vegetation. The simulations have been performed in a semi arid region in the South Western United States with the domain centered on a well-instrumented test basin - the Walnut Gulch Experimental Watershed. Energy balance as well as soil moisture measurements from the test basin are used to evaluate the simulations. We also use MODIS NDVI observations to evaluate the simulated vegetation spatio-temporal dynamics.

  3. Long-range transport of atmospheric lead reaching Ny-Ålesund: Inter-annual and seasonal variations of potential source areas

    NASA Astrophysics Data System (ADS)

    Bazzano, Andrea; Cappelletti, David; Udisti, Roberto; Grotti, Marco

    2016-08-01

    Atmospheric particulate matter (PM10) was collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) during spring and summer from 2010 to 2014 and analysed for lead content, enrichment factor and isotopic composition (208Pb/206Pb and 207Pb/206Pb). It was found that atmospheric lead was mainly of anthropogenic origin and neither its mean concentration, nor its isotopic composition was subjected to significant inter-annual differences (p-value > 0.1). Seasonal differences in both lead content and isotopic compositions occurred (p-value < 0.001), with the exception of 2013 samples. Lead content in spring was higher than in summer. Isotopic analysis indicated that mining and smelting activities in the Rudny Altay region (Central Eurasia), as well as industrial emission in north-eastern North America, were the main sources of atmospheric lead in spring and summer, respectively. During 2013, no significant differences between the two seasons were found (p-value > 0.3), showing a prolonged influence of Eurasian sources also in summer. The results obtained by the Pb isotopic composition were corroborated by a back-trajectory cluster analysis of air-masses reaching the sampling site.

  4. Inter-annual variability of urolithiasis epidemic from semi-arid part of Deccan Volcanic Province, India: climatic and hydrogeochemical perspectives.

    PubMed

    Kale, Sanjay S; Ghole, Vikram Shantaram; Pawar, N J; Jagtap, Deepak V

    2014-01-01

    Semi-arid Karha basin from Deccan Volcanic Province, India was investigated for inter-annual variability of urolithiasis epidemic. The number of reported urolith patient, weather station data and groundwater quality results was used to assess impact of geoenvironment on urolithiasis. Data of 7081 urolith patient were processed for epidemiological study. Gender class, age group, year-wise cases and urolith type were studied in epidemiology. Rainfall, temperature, pan evaporation and sunshine hours were used to correlate urolithiasis. Further, average values of groundwater parameters were correlated with the number of urolith episodes. A total of 52 urolith samples were collected from hospitals and analysed using FTIR technique to identify dominant urolith type in study area. Result shows that male population is more prone, age group of 20-40 is more susceptible and calcium oxalate uroliths are dominant in study area. Year-wise distribution revealed that there is steady increase in urolithiasis with inflation in drought years. In climatic parameters, hot days are significantly correlated with urolithiasis. In groundwater quality, EC, Na and F are convincingly correlated with urolith patients, which concludes the strong relation between geo-environment and urolithiasis. PMID:23869912

  5. Inter-annual and Long-term Temperature Variations in the Mesopause Region at High Latitudes Generated by the Stratospheric QBO

    NASA Technical Reports Server (NTRS)

    Mayr, Hans G.; Mengel, John G.; Huang, Frank T.

    2007-01-01

    The Numerical Spectral Model (NSM) simulates the Quasi-biennial Oscillation (QBO) that dominates the zonal circulation of the lower stratosphere at low latitudes. In the model, the QBO is generated with parameterized small-scale gravity waves (GW), which are partially augmented in 3D with planetary waves owing to baroclinic instability. Due to GW filtering, the QBO extends into the upper mesosphere, evident in UARS zonal wind and TIMED temperature measurements. While the QBO zonal winds are confined to equatorial latitudes, even in simulations with latitude-independent wave source, the associated temperature variations extend to high latitudes. The meridional circulation redistributes some of the QBO energy to focus it partially onto the Polar Regions. The resulting QBO temperature variations away from the equator tend to increase at higher altitudes to produce inter-annual variations that can exceed 5 K in the polar mesopause region -- and our 3D model simulations show that the effect is variable from year to year and can produce large differences between the two hemispheres, presumably due to interactions involving the seasonal variations. Modeling studies with the NSM have shown that long-term variations can also be generated by the QBO interacting with the seasonal cycles through OW node-filtering. A 30-month QBO, optimally synchronized by the 6-month Semi-Annual Oscillation (SAO), thus produces a 5-year or semi-decadal (SD) oscillation -- and observational evidence for that has been provided by a recent analysis of stratospheric NCEP data. In a simulation with the 2D version of the NSM, this SD oscillation extends into the upper mesosphere, and we present results to show that the related temperature variations could contribute significantly to the long-term variations of the polar mesopause region. Quasi-decadal variations could furthermore arise from the modeled solar cycle modulations of the QBO and 12-month annual oscillation. Our numerical results are

  6. Topographic control of snowpack distribution in a small catchment in the central Spanish Pyrenees: intra- and inter-annual persistence

    NASA Astrophysics Data System (ADS)

    Revuelto, J.; López-Moreno, J. I.; Azorin-Molina, C.; Vicente-Serrano, S. M.

    2014-10-01

    days on which the snowpack was thinner and more patchily. Despite the differences in climatic conditions in the 2012 and 2013 snow seasons, similarities in snow distributions patterns were observed which are directly related to terrain topographic characteristics.

  7. Variation and genetic structure of Tunisian Festuca arundinacea populations based on inter-simple sequence repeat pattern.

    PubMed

    Chtourou-Ghorbel, N; Elazreg, H; Ghariani, S; Ben Mheni, N; Sekmani, M; Chakroun, M; Trifi-Farah, N

    2015-01-01

    Tunisian tall fescue (Festuca arundinacea Schreb.) is an important grass for forages or soil conservation, particularly in marginal sites. Inter-simple sequence repeats were used to estimate genetic diversity within and among 8 natural populations and 1 cultivar from Northern Tunisia. A total of 181 polymorphic inter-simple sequence repeat markers were generated using 7 primers. Shannon's index and analysis of molecular variance evidenced a high molecular polymorphism at intra-specific levels for wild and cultivated accessions, showing that Tunisian tall fescue germplasm constitutes an important pool of diversity. Within-population variation accounted for 39.42% of the total variation, but no regional differentiation was discernible to designate close relationships between regions. Most of the variation (GST = 67%) occurred between populations, rather than within populations. The ɸST (0.60) revealed high population structuring. Additionally, the population structure was independent of the geographic origin and was not affected by environmental factors. The unweighted pair group method with arithmetic mean tree based on genetic similarity and principal coordinate analysis based on coefficient similarity illustrated that continental populations from the proximate localities of Beja and Jendouba were genetically closely related, while the wild Skalba population from the littoral Tunisian locality was the most diverse from the others. Moreover, great molecular similarity of the spontaneous population Sedjnane originated from the mountain areas was revealed with the local cultivar Mornag. The observed genetic diversity can be used to implement conservation strategies and breeding programs for improving forage crops in Tunisia. PMID:25966071

  8. Annual migratory patterns of long-billed curlews in the American west

    USGS Publications Warehouse

    Page, Gary W.; Warnock, Nils; Tibbitts, T. Lee; Jorgensen, Dennis; Hartman, C. Alex; Stenzel, Lynne E.

    2014-01-01

    Effective conservation of migratory species requires comprehensive knowledge of annual movement patterns. Such information is sparse for the Long-billed Curlew (Numenius americanus), a North American endemic shorebird of conservation concern. To test hypotheses about individual and area differences in migratory patterns across western North America, we tagged 29 curlews with satellite transmitters at breeding sites in Oregon, Nevada, and Montana. Transmissions from 28 birds for up to 4 years demonstrated that all wintered within the species’ known winter range, including 9 from Oregon tracked to agricultural areas of California’s Central Valley; 5 from Nevada tracked to the Central Valley, northern Gulf of California, or west coast of Baja California, Mexico; and 14 from Montana that wintered inland, from the Texas Panhandle south to the Mexican Plateau, or near the Gulf of Mexico. Montana breeders migrated east of the Rocky Mountains and traveled more than twice the distance of Oregon and Nevada breeders. Montana birds also stopped more often and longer during most passages. As a group, curlews arrived on their Oregon breeding grounds earlier than in Montana, while males preceded females in Montana and possibly Oregon. No consistent pattern emerged between sexes in departure from breeding areas, although within pairs males departed later than their mates. Individuals exhibited strong fidelity to breeding and wintering sites, and many birds showed a strong propensity for agricultural regions during winter. Our results underscore the importance of studying

  9. Modeling effects of inter-annual variability in meteorological and land use conditions on coupled water and energy cycling in the cultivated African Sahel

    NASA Astrophysics Data System (ADS)

    Velluet, C.; Demarty, J.; Cappelaere, B.; Braud, I.; Boulain, N.; Favreau, G.; Charvet, G.; Ramier, D.; Issoufou, H.; Boucher, M.; Mainassara, I.; Chazarin, J.; Oï, M.; Yahou, H.; Benarrosh, N.; Ibrahim, M.

    2012-12-01

    In the dry tropics in general and in the African Sahel in particular, hydro-ecosystems are very sensitive to climate variability and land management. In the Niamey region of South-West Niger, a severe multi-decadal drought together with large-scale vegetation clearing coincided with an unexpected increase in surface and ground water resources. Such an apparent paradoxical situation illustrates the complex way in which climate and land cover interactions control the Sahelian water cycle dynamics. This stresses the importance of understanding and reliably modeling water/energy transfers in the local soil-plant-atmosphere system, under contrasted meteorological and surface conditions. This study investigates the effects of the inter-annual variability of meteorological and land use conditions on the coupled water and energy cycles in the cultivated Sahel over a 5-year period. This is based on a comprehensive multi-year field dataset acquired for a millet crop field and a fallow savannah, the two main land cover types of South-West Niger (Wankama catchment in the mesoscale AMMA-CATCH Niger observatory, part of the French-initiated RBV network). It includes atmospheric forcing, seasonal course of vegetation phenology, soil properties and model validation variables (net radiation, turbulent fluxes, soil heat/water profiles), for the two fields. The study area is typical of Central Sahel conditions, with 400-600 mm annual rainfall concentrated in the 4-5 month wet season. Soils are mainly sandy and prone to surface crusting, leading to a strong vertical contrast in hydrodynamic properties. The SiSPAT process-based model used solves the 1D mass and heat transfer system of equations in the soil, including vapor phase and coupled with a two-component (bare soil and vegetation) water and energy budget at the surface-atmosphere interface. The study explores whether such a model can be accurately calibrated and validated for the two sites using realistic-parameter values. The

  10. Inter-annual and seasonal variability of the diurnal behavior of aureole scattering phase function at the aerosol monitoring station of LOA IAO SB RAS in 2010-2014

    NASA Astrophysics Data System (ADS)

    Polkin, Vas. V.; Polkin, Vic. V.

    2015-11-01

    Inter-annual and seasonal variability of diurnal variations of the aureole scattering phase functions is analyzed. The data obtained by means of the completely automated aureole photometer with a closed scattering volume. Regular round-the-clock hourly measurements of the aureole scattering phase function were carried out in 2010-2014 at the Aerosol monitoring station of LOA IAO SB RAS in the region of scattering angles φ = 1.2 - 20° at the wavelength of 650 nm.

  11. Integrating inter- and intra-annual tree-ring width, carbon isotopes and anatomy: responses to climate variability in a temperate oak forest

    NASA Astrophysics Data System (ADS)

    Granda, Elena; Bazot, Stéphane; Fresneau, Chantal; Boura, Anaïs; Faccioni, Georgia; Damesin, Claire

    2015-04-01

    While many forests are experiencing strong tree declines due to climate change in temperate ecosystems, others nearby to those declining show no apparent signs of decline. This could be due to particular microsite conditions or, for instance, to a higher plasticity of given traits that allow a better performance under stressful conditions. We studied oak functional mechanisms (Quercus petraea) leading to the apparently healthy status of the forest and their relation to the observed climatic variability. This study was conducted in the Barbeau Forest (northern France), where cores from mature trees were collected. Three types of functional traits (secondary growth, physiological variables - δ13C and derived Δ13C and iWUE- and several anatomical ones -e.g. vessel area, density-) were recorded for each ring for the 1991-2011 period, distinguishing EW from LW in all measured traits. Among the three types of functional traits, those related to growth experienced the highest variability both between years and between individuals, followed by anatomical and physiological ones. Secondary growth maintained a constant trend during the study period. Instead, ring, EW and LW δ13C slightly declined from 1991 to 2011. Additional intra-ring δ13C analyses allowed for a more detailed understanding of the seasonal dynamics within each year. In particular, the year 2007 (an especially favorable climatic year during the growing season) showed the lowest δ13C values during the EW-LW transition for the whole study period. Inter-annual anatomical traits varied in their responses, but in general, no temporal trends were found. The results from structural equation modeling (SEM) showed direct relationships of seasonal climate and growth, as well as indirect relationships mediated by anatomical and physiological traits. We further discuss the implications of these results on future forest responses to ongoing climate changes.

  12. Inter-annual trend of the primary contribution of ship emissions to PM2.5 concentrations in Venice (Italy): Efficiency of emissions mitigation strategies

    NASA Astrophysics Data System (ADS)

    Contini, Daniele; Gambaro, Andrea; Donateo, Antonio; Cescon, Paolo; Cesari, Daniela; Merico, Eva; Belosi, Franco; Citron, Marta

    2015-02-01

    Ships and harbour emissions are currently increasing, due to the increase of tourism and trade, with potential impact on global air pollution and climate. At local scale, in-port ship emissions influence air quality in coastal areas impacting on health of coastal communities. International legislations to reduce ship emissions, both at Worldwide and European levels, are mainly based on the use of low-sulphur content fuel. In this work an analysis of the inter-annual trends of primary contribution, ε, of tourist shipping to the atmospheric PM2.5 concentrations in the urban area of Venice has been performed. Measurements have been taken in the summer periods of 2007, 2009 and 2012. Results show a decrease of ε from 7% (±1%) in 2007 to 5% (±1%) in 2009 and to 3.5% (±1%) in 2012. The meteorological and micrometeorological conditions of the campaigns were similar. Tourist ship traffic during measurement campaigns increased, in terms of gross tonnage, of about 25.4% from 2007 to 2009 and of 17.6% from 2009 to 2012. The decrease of ε was associated to the effect of a voluntary agreement (Venice Blue Flag) for the use of low-sulphur content fuel enforced in the area between 2007 and 2009 and to the implementation of the 2005/33/CE Directive in 2010. Results show that the use of low-sulphur fuel could effectively reduce the impact of shipping to atmospheric primary particles at local scale. Further, voluntary agreement could also be effective in reducing the impact of shipping on local air quality in coastal areas.

  13. Seasonal and Inter-annual Changes in Photosynthetic and Soil Respiratory Processes in a Cool-temperate Deciduous Forest on a Mountainous Landscape in Japan.

    NASA Astrophysics Data System (ADS)

    Muraoka, H.; Noh, N. J.; Saitoh, T. M.; Nagao, A.; Noda, H. M.; Kuribayashi, M.; Nagai, S.

    2015-12-01

    Carbon budget of terrestrial ecosystems is one of the most crucial themes in ecosystem sciences under current and future climate changes as it would affect our Earth system. Remote sensing and modeling analysis studies from continental to global scales have been indicating that the recent climate change is influential to photosynthetic processes in terrestrial vegetation such as forests and grasslands, by altering phenology (seasonal change) and foliage biomass. In addition, increasing temperature and possibly changing photosynthetic activities of plants are influential to soil carbon dynamics. Our deeper and broader understandings on such photosynthetic and respiratory processes governing carbon cycle and hence budget of terrestrial ecosystems are critical to detect the changes of ecosystem processes and the functions in changing environments, as they would influence the biodiversity, ecosystem services and Earth system.In order to reveal the nature of temporal changes in photosynthetic and respiratory processes in forest ecosystems, we have been conducting multi-disciplinary observations of ecophysiological and optical properties for canopy photosynthesis in a cool-temperate deciduous forest since 2003 ("Takayama site", contributing to AsiaFlux and JaLTER). In addition, open-field warming experiments have been conducted since 2011 to examine the possible influence of near-future warming condition on forest canopy photosynthesis and soil respiration. (1) Our long-term measurements of leaf and canopy photosynthesis revealed that their phenology is influenced by inter-annual variation of micrometeorological conditions. (2) Combined analysis of leaf-canopy photosynthesis and optical properties enabled us to estimate the forest photosynthetic productivity at regional scale by satellite data. (3) Open-field warming experiments suggested that tree foliage and soil processes would acclimate to near-future warming conditions.

  14. Inter-Segmental Coordination Pattern in Patients with Anterior Cruciate Ligament Deficiency during a Single-Step Descent

    PubMed Central

    Nematollahi, Mohammadreza; Razeghi, Mohsen; Mehdizadeh, Sina; Tabatabaee, Hamidreza; Piroozi, Soraya; Rojhani Shirazi, Zahra; Rafiee, Ali

    2016-01-01

    Anterior cruciate ligament injury is a debilitating pathology which may alter lower limb coordination pattern in both intact and affected lower extremities during activities of daily living. Emerging evidence supports the notion that kinematic variables may not be a good indicator to differentiate patients with anterior cruciate ligament deficiency during step descent task. The aim of the present study was to examine alterations in kinematics as well as coordination patterns and coordination variability of both limbs of these patients during a single step descent task. Continuous relative phase technique was used to measure coordination pattern and coordination variability between a group of anterior cruciate ligament deficient (n = 23) and a healthy control group (n = 23). A third order polynomial Curve fitting was utilized to provide a curve that best fitted to the data points of coordination pattern and coordination variability of the healthy control group. This was considered as a reference to compare to that of patient group using nonlinear regression analysis. The results of the present study demonstrated an altered coordination pattern of the supporting shank-thigh and the stepping foot-shank couplings in anterior cruciate ligament deficient subjects. It was further noticed that there was an increased coordination variability in foot-shank and shank-thigh couplings of both supporting and stepping legs. There was no significant difference in the hip, knee and ankle joints kinematics in either side of these patients. Anterior cruciate ligament deficient individuals showed altered strategies in both intact and affected legs, with increased coordination variability. Kinematic data did not indicate any significant difference between the two groups. It could be concluded that more sophisticated dynamic approach such as continuous relative phase would uncover discrepancies between the healthy and anterior cruciate ligament deficient individuals. PMID:26900698

  15. Inter-individual differences in breathing pattern at high levels of incremental cycling exercise in healthy subjects.

    PubMed

    Gravier, Gilles; Delliaux, Stephane; Delpierre, Stephane; Guieu, Regis; Jammes, Yves

    2013-10-01

    Interindividual differences in the rate of changes in tidal volume (V(T)) and respiratory frequency (f(R)) were examined during a maximal incremental cycling exercise. The gain of the inspiratory off-switch reflex was inferred from the V(T) vs. inspiratory duration (T(i)) relationship. Some subjects also executed a static handgrip exercise, used as a "non-dynamic" exercise trial to study patterning of breathing. Above the ventilatory threshold (V(Th)), two patterns of response were identified: in group 1, the rate of change in V(T) significantly increased, while in group 2 the breakpoint of ventilation solely resulted from f(R) increase. After the respiratory compensation point, a tachypnoeic response always occurred. A leftward shift of the V(T) vs. Ti relationship, i.e., an inspiratory off-switch reflex, was measured during the handgrip in group 2 subjects as well as marked f(R) variations. Our study identifies two different patterns of breathing after the V(Th). The subjects who present a tachypnoeic response to exercise above the V(Th) have a higher sensitivity to pulmonary inflation and their tachypnoeic response was ubiquitous during a maximal handgrip test. PMID:23832014

  16. Understanding Historical Human Migration Patterns and Interbreeding (JGI Seventh Annual User Meeting 2012: Genomics of Energy and Environment)

    SciTech Connect

    Willerslev, Eske

    2012-03-21

    Eske Willerslev from the University of Copenhagen on "Understanding Historical Human Migration Patterns and Interbreeding Using the Ancient Genomes of a Palaeo-Eskimo and an Aboriginal Australian" at the 7th Annual Genomics of Energy & Environment Meeting on March 21, 2012 in Walnut Creek, California.

  17. Understanding Historical Human Migration Patterns and Interbreeding (JGI Seventh Annual User Meeting 2012: Genomics of Energy and Environment)

    ScienceCinema

    Willerslev, Eske [University of Copenhagen

    2013-01-15

    Eske Willerslev from the University of Copenhagen on "Understanding Historical Human Migration Patterns and Interbreeding Using the Ancient Genomes of a Palaeo-Eskimo and an Aboriginal Australian" at the 7th Annual Genomics of Energy & Environment Meeting on March 21, 2012 in Walnut Creek, California.

  18. Analysis of the seasonal and inter-annual variations, and long-term trends of ozone in the metropolitan area of Monterrey, Mexico

    NASA Astrophysics Data System (ADS)

    Yassmany Hernández Paniagua, Iván; Clemitshaw, Kevin C.; Mendoza, Alberto

    2016-04-01

    Since 1993, high-precision and high-frequency measurements of ambient O3 have been recorded at 5 sites within the metropolitan area of Monterrey, the third largest city in Mexico. O3was measured by the Integral Environmental Monitoring System of the Nuevo Leon State Government using commercially available, conventional UV photometry instrumentation (precision better than ±1 ppb). The datasets exhibit variations on differing time-scales of minutes to hours, with evidence of seasonal cycles and inter-annual variability. The O3 diurnal cycles vary with length of daylight, which influences its formation and loss via photochemistry. No apparent influence is observed in the amplitudes of O3 diurnal cycles recorded during weekdays with higher emissions from fossil fuel combustion than at weekends, although larger amplitudes occur at sites with polluted air from industrial areas. Seasonal cycles are driven by the variation in solar radiation and changes in emissions of primary precursors, VOCs and NOX. Maximum O3 mixing ratios were recorded in spring, and minimum values in winter, with a secondary trough during summer due to the advection of clean air masses from the Gulf of Mexico. The largest spring maxima are recorded downwind of an industrial area likely due photochemical processing of VOCs and NOx, with the lowest recorded in a highly populated area due to reaction of O3 and NO. At all sites, decreasing seasonal amplitudes were observed during 1993-1998, followed by persistent increases from 1998 to 2014. Wind sector analyses were carried out by splitting the wind direction into 8 categories (45°). At all sites, the highest O3 mixing ratios were recorded from the E and SE sectors, with lowest values recorded in air masses from the W and NW. Wind sector analysis of primary precursors (such as VOCs, CO, NOX) reveal that sources are dominated by emissions from industrial regions in Monterrey and surrounding areas. The largest annual growth rates for the E and SE

  19. Regional and inter-annual variability in Atlantic zooplankton en route to the Arctic Ocean: potential effects of multi-path Atlantic water advection through Fram Strait and the Barents Sea

    NASA Astrophysics Data System (ADS)

    Kwasniewski, Slawomir; Gluchowska, Marta; Trudnowska, Emilia; Ormanczyk, Mateusz; Walczowski, Waldemar; Beszczynska-Moeller, Agnieszka

    2016-04-01

    The Arctic is among the regions where the climate change effects on ecosystem will be the most rapid and consequential, with Arctic amplification recognized as an integral part of the process. Great part of the changes are forced by advection of warm waters from the North Atlantic and the expected modifications of Arctic marine ecosystem will be induced not only by changing environmental conditions but also as a result of introducing Atlantic biota. Thus, the knowledge of physical and biological heterogeneity of Atlantic inflow is requisite for understanding the effects of climate change on biological diversity and ecosystem functioning in the Arctic. The complex and variable two-branched structure of the Atlantic Water flow via Fram Strait and the Barents Sea most likely has a strong influence on the ocean biology in these regions, especially in the pelagic realm. Zooplankton are key components of marine ecosystems which form essential links between primary producers and grazer/predator consumers, thus they are important for functioning of the biological carbon pump. Changes in zooplankton distribution and abundance may have cascading effects on ecosystem functioning, with regulatory effects on climate. Based on data collected in summers of 2012-2014, within the scope of the Polish-Norwegian PAVE research project, we investigate zooplankton distribution, abundance and selected structural characteristics of communities, in relation to water mass properties in the Atlantic Water complex flow to the Arctic Ocean. The main questions addressed here are: what are the differences in zooplankton patterns between the Fram Strait and Barents Sea branches, and how does the inter-annual variability of Atlantic Water advection relate to changes in zooplankton? The results of the investigation are precondition for foreseeing changes in the pelagic realm in the Arctic Ocean and are necessary for constructing and tuning plankton components of ecosystem models.

  20. Whisker isotopic signature depicts migration patterns and multi-year intra- and inter-individual foraging strategies in fur seals

    PubMed Central

    Cherel, Y.; Kernaléguen, L.; Richard, P.; Guinet, C.

    2009-01-01

    The movement and dietary history of individuals can be studied using stable isotope records in archival keratinous tissues. Here, we present a chronology of temporally fine-scale data on the trophic niche of otariid seals by measuring the isotopic signature of serially sampled whiskers. Whiskers of male Antarctic fur seals breeding at the Crozet Islands showed synchronous and regular oscillations in both their δ13C and δ15N values that are likely to represent their annual migrations over the long term (mean 4.8 years). At the population level, male Antarctic fur seals showed substantial variation in both δ13C and δ15N values, occupying nearly all the ‘isotopic space’ created by the diversity of potential oceanic habitats (from high Antarctica to the subtropics) and prey (from Antarctic krill to subantarctic and subtropical mesopelagic fishes). At the individual level, whisker isotopic signatures depict a large diversity of foraging strategies. Some seals remained in either subantarctic or Antarctic waters, while the migratory cycle of most animals encompassed a wide latitudinal gradient where they fed on different prey. The isotopic signature of whiskers, therefore, revealed new multi-year foraging strategies of male Antarctic fur seals and is a powerful tool for investigating the ecological niche during cryptic stages of mammals' life. PMID:19793740

  1. IRF5 Risk Polymorphisms Contribute to Inter-Individual Variance in Pattern-Recognition Receptor-Mediated Cytokine Secretion in Human Monocyte-Derived Cells

    PubMed Central

    Hedl, Matija; Abraham, Clara

    2012-01-01

    Monocyte-derived cells display highly variable cytokine secretion upon pattern-recognition receptor (PRR) stimulation across individuals; such variability likely affects inter-individual inflammatory/autoimmune disease susceptibility. To define mechanisms for this heterogeneity, we examined pattern recognition receptor (PRR)-induced monocyte-derived-cell cytokine secretion from a large cohort healthy individuals. Although cytokine secretion ranged widely among individuals, the magnitude of cytokine induction after individual Nod2 and TLR2 stimulation (a cohort of 86 individuals) or stimulation of multiple TLRs (a cohort of 77 individuals), either alone or in combination with Nod2, was consistent intra-individually across these stimuli. Nod2 and TLRs signal through interferon-regulatory-factor-5 (IRF5) and common IRF5 polymorphisms confer risk for autoimmunity. We find that cells from rs2004640 IRF5 risk-associated allele carriers secrete increased cytokines upon individual or synergistic PRR stimulation in a gene dose- and ligand dose-dependent manner in both monocyte-derived dendritic cells and macrophages. IRF5 expression knockdown in IRF5-risk-allele carrier cells significantly decreases PRR-induced cytokines. Moreover, we find that IRF5 knockdown profoundly decreases Nod2-mediated MAPK and NF-κB pathway activation, whereas the PI3K and mTOR pathways are not impaired. Finally, the IRF5 rs2004640 polymorphism is a major determinant of the variance (r2=0.53) in Nod2-induced cytokine secretion by monocyte-derived cells from different individuals. We therefore show a profound contribution of a single gene to the variance in inter-individual PRR-induced cytokines. The hyper-responsiveness of IRF5 disease-associated polymorphisms to a wide spectrum of microbial triggers has broad implications on global immunological responses, host defenses against pathogens and inflammatory/autoimmune disease susceptibility. PMID:22544929

  2. Intra- and inter-group coordination patterns reveal collective behaviors of football players near the scoring zone.

    PubMed

    Duarte, Ricardo; Araújo, Duarte; Freire, Luís; Folgado, Hugo; Fernandes, Orlando; Davids, Keith

    2012-12-01

    This study examined emergent coordination processes in collective patterns of behavior in 3 vs 3 sub-phases of the team sport of association football near the scoring zone. We identified coordination tendencies for the centroid (i.e., team center) and surface area (i.e., occupied space) of each sub-group of performers (n=20 plays). We also compared these kinematic variables at three key moments of play using mixed-model ANOVAs. The centroids demonstrated a strong symmetric relation that described the coordinated attacking/defending actions of performers in this sub-phase of play. Conversely, analysis of the surface area of each team did not reveal a clear coordination pattern between sub-groups. But the difference in the occupied area between the attacking and defending sub-groups significantly increased over time. Findings emphasized that major changes in sub-group behaviors occurred just before an assisted pass was made (i.e., leading to a loss of stability in the 3 vs 3 sub-phases). PMID:22513231

  3. Patterns and predictability in the intra-annual organic carbon variability across the boreal and hemiboreal landscape.

    PubMed

    Hytteborn, Julia K; Temnerud, Johan; Alexander, Richard B; Boyer, Elizabeth W; Futter, Martyn N; Fröberg, Mats; Dahné, Joel; Bishop, Kevin H

    2015-07-01

    Factors affecting total organic carbon (TOC) concentrations in 215 watercourses across Sweden were investigated using parameter parsimonious regression approaches to explain spatial and temporal variabilities of the TOC water quality responses. We systematically quantified the effects of discharge, seasonality, and long-term trend as factors controlling intra-annual (among year) and inter-annual (within year) variabilities of TOC by evaluating the spatial variability in model coefficients and catchment characteristics (e.g. land cover, retention time, soil type). Catchment area (0.18-47,000 km2) and land cover types (forests, agriculture and alpine terrain) are typical for the boreal and hemiboreal zones across Fennoscandia. Watercourses had at least 6 years of monthly water quality observations between 1990 and 2010. Statistically significant models (p<0.05) describing variation of TOC in streamflow were identified in 209 of 215 watercourses with a mean Nash-Sutcliffe efficiency index of 0.44. Increasing long-term trends were observed in 149 (70%) of the watercourses, and intra-annual variation in TOC far exceeded inter-annual variation. The average influences of the discharge and seasonality terms on intra-annual variations in daily TOC concentration were 1.4 and 1.3 mg l(-1) (13 and 12% of the mean annual TOC), respectively. The average increase in TOC was 0.17 mg l(-1)year(-1) (1.6% year(-1)). Multivariate regression with over 90 different catchment characteristics explained 21% of the spatial variation in the linear trend coefficient, less than 20% of the variation in the discharge coefficient and 73% of the spatial variation in mean TOC. Specific discharge, water residence time, the variance of daily precipitation, and lake area, explained 45% of the spatial variation in the amplitude of the TOC seasonality. Because the main drivers of temporal variability in TOC are seasonality and discharge, first-order estimates of the influences of climatic variability

  4. Differential responses of seabirds to inter-annual environmental change in the continental shelf and oceanic habitats of southeastern Bering Sea

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Kokubun, N.; Kikuchi, D. M.; Sato, N.; Takahashi, A.; Will, A.; Kitaysky, A. S.; Watanuki, Y.

    2015-11-01

    Seasonal sea-ice cover has been decreasing in the southeastern Bering Sea shelf, which might affect ecosystem dynamics and availability of food resources to marine top predators breeding in the region. In this study, we investigated the foraging responses of two seabird species, surface-foraging red-legged kittiwakes Rissa brevirostris (hereafter, RLKI) and pursuit-diving foraging thick-billed murres Uria lomvia (TBMU) to the inter-annual change in environmental conditions. Between the study years, winter ice retreated earlier and summer water temperatures were warmer in 2014 compared to those in 2013. At-sea distributions of RLKI and TBMU breeding on St. George Island, the largest seabird colony in the region, were recorded using GPS loggers, and blood samples were taken to examine their physiological condition and isotopic foraging niche in a given year. RLKI foraging occurred mostly over the oceanic basin in both years. TBMU, however, foraged mostly over the shelf, but showed a relatively higher use of the shelf break and oceanic basin in the colder year, 2013. The foraging distances from the colony peaked at 250-300 km in 2013 and, bimodally, at 150-250 and 300-350 km in 2014 for RLKI, and tended to be farther in 2013 compared to those in 2014 for TBMU. Plasma levels of corticosterone did not differ between years in RLKI, but differed in TBMU, showing higher levels of physiological stress incurred by murres during the colder year, 2013. δ13N (a proxy of trophic level of prey) did not differ between the years in either RLKI or TBMU, while δ13C (a proxy of prey origin) were lower in 2014 than in 2013 in both species, suggesting possible differences in influx of oceanic prey items into foraging areas. These results suggest that the response of ecosystem dynamics to climate variability in the southeast Bering Sea may differ between the ocean basin and continental shelf regions, which, in turn, may generate differential responses in seabirds relying on those

  5. Inter-annual variations in the abundance of young-of-the-year of migratory fishes in the Upper Paraná River floodplain: relations with hydrographic attributes.

    PubMed

    Suzuki, H I; Agostinho, A A; Bailly, D; Gimenes, M F; Júlio, H F; Gomes, L C

    2009-06-01

    In this study, we identified and characterized the hydrographic attributes related to the success of recruitment of migratory fishes in the Upper Paraná River floodplain. To achieve our objectives, we analyzed inter-annual variations in the abundance of young-of-the-year (YOY; index of recruitment) of six migratory species and their relations with hydrographic attributes. Recruitment was related to the intensity, duration (in different fluviometrical levels), elasticity, number of pulses, greater uninterrupted overflow and delay of the floods (all obtained using the PULSO software). Collections of fish were conducted in the period between January 1987 and November 2007 in distinct environments (river channels, secondary channels and connected and disconnected floodplain lakes) distributed along three subsystems (Paraná, Baía and Ivinheima). Relations between recruitment and the attributes of interest were determined through analysis of covariance. In the studied period, the highest abundances of YOY were registered in 2007, followed by 1992, 1993, 2005 and 1988. The abundance of YOY was positively correlated with an intensity of high water levels (potamophase) and the duration of potamophase 1 and negatively with the duration of low water levels (limnophase) and a delay of flood. Higher hydrometric levels (540 and 610 cm for Paraná and 325 and 450 cm for Ivinheima) and greatest uninterrupted overflow presented different relations (significant interactions) among subsystems, but all with positive effects on recruitment. Results evidenced that recruitment responded better when floods started in January with potamophase intensities above 610 cm and water levels above 450 cm over a period of 50 days and repeated every two years (or > 610 cm for 38 days and repeated every two or three years). Therefore, artificial control of the floods at intervals of two or three years by manipulating the discharge of dams located upstream from the floodplain in a way that promotes

  6. Inter-annual variability of surface ozone at coastal (Dumont d'Urville, 2004-2014) and inland (Concordia, 2007-2014) sites in East Antarctica

    NASA Astrophysics Data System (ADS)

    Legrand, Michel; Preunkert, Susanne; Savarino, Joël; Frey, Markus M.; Kukui, Alexandre; Helmig, Detlev; Jourdain, Bruno; Jones, Anna E.; Weller, Rolf; Brough, Neil; Gallée, Hubert

    2016-07-01

    Surface ozone has been measured since 2004 at the coastal East Antarctic site of Dumont d'Urville (DDU), and since 2007 at the Concordia station located on the high East Antarctic plateau. This paper discusses long-term changes, seasonal and diurnal cycles, as well as inter-annual summer variability observed at these two East Antarctic sites. At Concordia, near-surface ozone data were complemented by balloon soundings and compared to similar measurements done at the South Pole. The DDU record is compared to those obtained at the coastal site of Syowa, also located in East Antarctica, as well as the coastal sites of Neumayer and Halley, both located on the coast of the Weddell Sea in West Antarctica. Surface ozone mixing ratios exhibit very similar seasonal cycles at Concordia and the South Pole. However, in summer the diurnal cycle of ozone is different at the two sites with a drop of ozone in the afternoon at Concordia but not at the South Pole. The vertical distribution of ozone above the snow surface also differs. When present, the ozone-rich layer located near the ground is better mixed and deeper at Concordia (up to 400 m) than at the South Pole during sunlight hours. These differences are related to different solar radiation and wind regimes encountered at these two inland sites. DDU appears to be the coastal site where the impact of the late winter/spring bromine chemistry is the weakest, but where the impact of elevated ozone levels caused by NOx snow emissions from the high Antarctic plateau is the highest. The highest impact of the bromine chemistry is seen at Halley and Neumayer, and to a lesser extent at Syowa. These three sites are only weakly impacted by the NOx chemistry and the net ozone production occurring on the high Antarctic plateau. The differences in late winter/spring are attributed to the abundance of sea ice offshore from the sites, whereas those in summer are related to the topography of East Antarctica that promotes the katabatic flow

  7. How tropical cyclone inter-annual timing and trajectory control gross primary productivity in the SE US at seasonal and annual timescales and impacts on mountain forest eco-hydrology

    NASA Astrophysics Data System (ADS)

    Lowman, L.; Barros, A.

    2015-12-01

    Tropical cyclones (TCs) are an important source of freshwater input to the SE US eco-hydrologic function. Soil moisture, a temporal integral of precipitation, is critical to plant photosynthesis and carbon assimilation. In this study, we investigate the impact TCs have on gross primary productivity (GPP) in the SE US using the physically-based Duke Coupled Hydrology Model with Vegetation (DCHM-V) which includes coupled water and energy cycles and a biochemical representation of photosynthesis. A parsimonious evaluation of model-estimated GPP against all available AmeriFlux data in the SE US is presented. We characterize the seasonality of vegetation activity in the SE US by simulating water, energy, and carbon fluxes using the DCHM-V at high spatial (4 km) and temporal (30-min) resolution over the period 2002 - 2012. The model is run offline using atmospheric forcing data from NLDAS-2, precipitation from StageIV, and phenology indices from MODIS FPAR/LAI. Analysis of model results show the tendency for low GPP to occur in the Appalachian Mountains during peak summer months when water stress limits stomatal function. We contrast these simulations with model runs where periods of TC activity are replaced with the monthly climatological diurnal cycle from NARR. Results show that the timing and trajectory of TCs are key to understanding their impact on GPP across the SE US. Specifically: 1) Timing of moisture input from TCs greatly influences the vegetation response. TCs during peak summer months increase GPP and years with TCs falling in peak summer months see much higher annual GPP averages; 2) Years of drought and low plant productivity (2006-2007, 2011-2012) in the SE US tend to have TCs that fall later in the year when the additional moisture input does not have a significant impact on vegetation activity; and 3) TC path impacts regional GPP averages. The mountain region shows large inter- and intra-annual variability in plant productivity and high sensitivity to

  8. Dosimetric consequences of inter-fraction breathing-pattern variation on radiotherapy with personalized motion-assessed margins

    NASA Astrophysics Data System (ADS)

    Kavanagh, A.; McQuaid, D.; Evans, P.; Webb, S.; Guckenberger, M.

    2011-11-01

    The data from eight patients who had undergone stereotactic body radiotherapy were selected due to their 4D-CT planning scans showing that their tumours had respiratory induced motion trajectories of large amplitude (greater than 9 mm in cranio-caudal direction). Radiotherapy plans with personalized motion-assessed margins were generated for these eight patients. The margins were generated by inverse 4D planning on an eight-bin phase-sorted 4D-CT scan. The planning was done on an in-house software system with a non-rigid registration stage being completed using freely available software. The resultant plans were then recalculated on a 4D-CT scan taken later during the course of treatment. Simulated image-guided patient set-up was used to align the geometric centres of the tumour region and minimize any misalignment between the two reconstructions. In general, the variation in the patient breathing patterns was found to be very small. Consequently, the degradation of the mean dose to the tumour region was found to be around a few percent (<3%) and hence was not a large effect.

  9. Geospatial and temporal patterns of annual cholera outbreaks in Matlab, Bangladesh

    NASA Astrophysics Data System (ADS)

    Majumder, M. S.; de Klerk, K.; Meyers, D.

    2012-12-01

    Cholera is a waterborne diarrheal disease endemic to Bangladesh, resulting in 1 million diagnoses annually. Such disease burden results in incalculable lost wages and treatment expenses, taken from the pockets of an already impoverished society. Two seasonally correlated outbreaks of cholera occur in Bangladesh every year. In the spring and early summer, the Bay of Bengal - which serves as a natural reservoir for the cholera bacteria - flows inland, causing the first outbreak amongst coastal communities. Waste containing the cholera bacteria enters the sewage system and remains untreated due to poor water and sanitation infrastructure. Therefore, during the following monsoon season, flooding of cholera-contaminated sewage into drinking water sources results in a second outbreak. Though considered common knowledge among local populations, this geographic and temporal progression has not been empirically verified in the current literature. The aim of our ongoing study is to systematically analyze the seasonal trajectory of endemic cholera in Bangladesh. This paper discusses the results obtained from a comprehensive survey of available cholera data from the International Centre of Diarrheal Disease Research, Bangladesh (ICDDR,B) in Matlab, Bangladesh. Matlab thana is a near-coastal community that consists of 142 villages. Monsoon season takes place from June through October. Due to its proximity to the Meghna River, which opens into the Bay of Bengal, the area experiences significant flooding during these months. Using 10 years of geographically referenced cholera data, cases were plotted in time and space. Preliminary patterns suggest that villages closer to the Meghna River experience the majority of the area's cholera outbreaks and that case count is highest in late spring and late fall. April/May and November/December represent 25% and 23% of total annual case counts respectively. Moreover, villages further from the coastline demonstrate 57% higher relative

  10. Mouse white adipocytes and 3T3-L1 cells display an anomalous pattern of carnitine palmitoyltransferase (CPT) I isoform expression during differentiation. Inter-tissue and inter-species expression of CPT I and CPT II enzymes.

    PubMed Central

    Brown, N F; Hill, J K; Esser, V; Kirkland, J L; Corkey, B E; Foster, D W; McGarry, J D

    1997-01-01

    The outer mitochondrial membrane enzyme carnitine palmitoyltransferase I (CPT I) represents the initial and regulated step in the beta-oxidation of fatty acids. It exists in at least two isoforms, denoted L (liver) and M (muscle) types, with very different kinetic properties and sensitivities to malonyl-CoA. Here we have examined the relative expression of the CPT I isoforms in two different models of adipocyte differentiation and in a number of rat tissues. Adipocytes from mice, hamsters and humans were also evaluated. Primary monolayer cultures of undifferentiated rat preadipocytes expressed solely L-CPT I, but significant levels of M-CPT I emerged after only 3 days of differentiation in vitro; in the mature cell M-CPT I predominated. In sharp contrast, the murine 3T3-L1 preadipocyte expressed essentially exclusively L-CPT I, both in the undifferentiated state and throughout the differentiation process in vitro. This was also true of the mature mouse white fat cell. Fully developed adipocytes from the hamster and human behaved similarly to those of the rat. Thus the mouse white fat cell differs fundamentally from those of the other species examined in terms of tis choice of a key regulatory enzyme in fatty acid metabolism. In contrast, brown adipose tissue from all three rodents displayed the same isoform profiles, each expressing overwhelmingly M-CPT I. Northern blot analysis of other rat tissues established L-CPT I as the dominant isoform not only in liver but also in kidney, lung, ovary, spleen, brain, intestine and pancreatic islets. In addition to its primacy in skeletal muscle, heart and fat, M-CPT I was also found to dominate the testis. The same inter-tissue isoform pattern (with the exception of white fat) was found in the mouse. Taken together, the data bring to light an intriguing divergence between white adipocytes of the mouse and other mammalian species. They also raise a cautionary note that should be considered in the choice of animal model used