Science.gov

Sample records for recurrent interannual climate

  1. Recurrent Interannual Climate Modes and Teleconnection Linking North America Warm Season Precipitation Anomalies to Asia Summer Monsoon Variability

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Weng, H. Y.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    In this paper, we present results showing that summertime precipitation anomalies over North America and East Asia may be linked via pan-Pacific teleconnection patterns, which are components of two dominant recurring global climate modes. The first mode (Mode-1) features an inverse relationship between rainfall anomaly over the US Midwest/central to the eastern/southeastern regions, coupled to a mid-tropospheric high-low pressure system over the northwest and southeast of the US, which regulates low level moisture transport from the Gulf of Mexico to the Midwest. The regional circulation pattern appears to be a part of a global climate mode spanning Eurasia, the North Pacific, North America, and the Atlantic. This mode is associated with coherent fluctuations of jetstream variability over East Asia, and Eurasia, SST in the North Pacific and the North Atlantic. While Mode-1 is moderately correlated with El Nino-Southern Oscillation (ENSO), it appears to be distinct from it, with strong influences from mid-latitude or possibly from higher latitude processes. Results show that Mode-1 not only has an outstanding contribution to the great flood of 1993, it has large contribution to the US precipitation anomalies in other years. Also noted is an apparent increase in influence of Mode-1 on US summertime precipitation in the last two decades since 1977.

  2. Cirrus feedback on interannual climate fluctuations

    SciTech Connect

    Zhou, C.; Dessler, A. E.; Zelinka, M. D.; Yang, P.; Wang, T.

    2014-12-28

    Cirrus clouds are not only important in determining the current climate, but also play an important role in climate change and variability. Analysis of satellite observations shows that the amount and altitude of cirrus clouds (optical depth <3.6, cloud top pressure <440 hPa) increase in response to inter-annual surface warming. Thus, cirrus clouds are likely to act as a positive feedback on short-term climate fluctuations, by reducing the planet’s ability to radiate longwave radiation to space in response to planetary surface warming. Using cirrus cloud radiative kernels, the magnitude of cirrus feedback is estimated to be 0.20±0.21W/m2/°C, which is comparable to the surface albedo feedback. Most of the cirrus feedback comes from increasing cloud amount in the tropical tropopause layer (TTL) and subtropical upper troposphere.

  3. Recent frequency component changes in interannual climate variability

    NASA Astrophysics Data System (ADS)

    Peel, Murray C.; McMahon, Thomas A.

    2006-08-01

    The potential impact of climate change on the variability structure of climate has been investigated predominately through changes to extreme event frequency or the shape of the daily frequency distribution. Recent change to interannual climate variability has received less attention. Here we report that the interannual variability of temperature and precipitation has marginally decreased since 1970. However, within this marginal decrease the inter-decadal component of interannual variability has decreased for both temperature and precipitation. The temperature results are consistent across urban and rural stations indicating that they are not due to any urbanisation effect.

  4. Multi-Wheat-Model Ensemble Responses to Interannual Climate Variability

    NASA Technical Reports Server (NTRS)

    Ruane, Alex C.; Hudson, Nicholas I.; Asseng, Senthold; Camarrano, Davide; Ewert, Frank; Martre, Pierre; Boote, Kenneth J.; Thorburn, Peter J.; Aggarwal, Pramod K.; Angulo, Carlos

    2016-01-01

    We compare 27 wheat models' yield responses to interannual climate variability, analyzed at locations in Argentina, Australia, India, and The Netherlands as part of the Agricultural Model Intercomparison and Improvement Project (AgMIP) Wheat Pilot. Each model simulated 1981e2010 grain yield, and we evaluate results against the interannual variability of growing season temperature, precipitation, and solar radiation. The amount of information used for calibration has only a minor effect on most models' climate response, and even small multi-model ensembles prove beneficial. Wheat model clusters reveal common characteristics of yield response to climate; however models rarely share the same cluster at all four sites indicating substantial independence. Only a weak relationship (R2 0.24) was found between the models' sensitivities to interannual temperature variability and their response to long-termwarming, suggesting that additional processes differentiate climate change impacts from observed climate variability analogs and motivating continuing analysis and model development efforts.

  5. Communicating uncertainty in seasonal and interannual climate forecasts in Europe.

    PubMed

    Taylor, Andrea L; Dessai, Suraje; de Bruin, Wändi Bruine

    2015-11-28

    Across Europe, organizations in different sectors are sensitive to climate variability and change, at a range of temporal scales from the seasonal to the interannual to the multi-decadal. Climate forecast providers face the challenge of communicating the uncertainty inherent in these forecasts to these decision-makers in a way that is transparent, understandable and does not lead to a false sense of certainty. This article reports the findings of a user-needs survey, conducted with 50 representatives of organizations in Europe from a variety of sectors (e.g. water management, forestry, energy, tourism, health) interested in seasonal and interannual climate forecasts. We find that while many participating organizations perform their own 'in house' risk analysis most require some form of processing and interpretation by forecast providers. However, we also find that while users tend to perceive seasonal and interannual forecasts to be useful, they often find them difficult to understand, highlighting the need for communication formats suitable for both expert and non-expert users. In addition, our results show that people tend to prefer familiar formats for receiving information about uncertainty. The implications of these findings for both the providers and users of climate information are discussed.

  6. Seasonal and interannual variations of atmospheric CO2 and climate

    USGS Publications Warehouse

    Dettinger, M.D.; Ghil, M.

    1998-01-01

    Interannual variations of atmospheric CO2 concentrations at Mauna Loa are almost masked by the seasonal cycle and a strong trend; at the South Pole, the seasonal cycle is small and is almost lost in the trend and interannual variations. Singular-spectrum analysis (SSA) issued here to isolate and reconstruct interannual signals at both sites and to visualize recent decadal changes in the amplitude and phase of the seasonal cycle. Analysis of the Mauna Loa CO2 series illustrates a hastening of the CO2 seasonal cycle, a close temporal relation between Northern Hemisphere (NH) mean temperature trends and the amplitude of the seasonal CO2 cycle, and tentative ties between the latter and seasonality changes in temperature over the NH continents. Variations of the seasonal CO2 cycle at the South Pole differ from those at Mauna Loa: it is phase changes of the seasonal cycle at the South Pole, rather than amplitude changes, that parallel hemispheric and global temperature trends. The seasonal CO2 cycles exhibit earlier occurrences of the seasons by 7 days at Mauna Loa and 18 days at the South Pole. Interannual CO2 variations are shared at the two locations, appear to respond to tropical processes, and can be decomposed mostly into two periodicities, around (3 years)-1 and (4 years)-1, respectively. Joint SSA analyses of CO2 concentrations and tropical climate indices isolate a shared mode with a quasi-triennial (QT) period in which the CO2 and sea-surface temperature (SST) participation are in phase opposition. The other shared mode has a quasi-quadrennial (QQ) period and CO2 variations are in phase with the corresponding tropical SST variations throughout the tropics. Together these interannual modes exhibit a mean lag between tropical SSTs and CO2 variations of about 6-8 months, with SST leading. Analysis of the QT and QQ signals in global gridded SSTs, joint SSA of CO2 and ??13C isotopic ratios, and SSA of CO2 and NH-land temperatures indicate that the QT variations in

  7. Strong Seasonality and Interannual Recurrence in Marine Myovirus Communities

    PubMed Central

    Chow, C.-E. T.; Johannessen, T.; Fuhrman, J. A.; Thingstad, T. F.; Sandaa, R. A.

    2013-01-01

    The temporal community dynamics and persistence of different viral types in the marine environment are still mostly obscure. Polymorphism of the major capsid protein gene, g23, was used to investigate the community composition dynamics of T4-like myoviruses in a North Atlantic fjord for a period of 2 years. A total of 160 unique operational taxonomic units (OTUs) were identified by terminal restriction fragment length polymorphism (TRFLP) of the gene g23. Three major community profiles were identified (winter-spring, summer, and autumn), which resulted in a clear seasonal succession pattern. These seasonal transitions were recurrent over the 2 years and significantly correlated with progression of seawater temperature, Synechococcus abundance, and turbidity. The appearance of the autumn viral communities was concomitant with the occurrence of prominent Synechococcus blooms. As a whole, we found a highly dynamic T4-like viral community with strong seasonality and recurrence patterns. These communities were unexpectedly dominated by a group of persistently abundant viruses. PMID:23913432

  8. Intraseasonal and Interannual Variability of Mars Present Climate

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1996-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. The focus of this JRI has been to investigate the nature of intraseasonal and interannual variability of Mars'present climate. We have applied a three-dimensional climate model based on the full hydrostatic primitive equations to determine the spatial, but primarily, the temporal structures of the planet's large-scale circulation as it evolves during a given seasonal advance, and, over multi-annual cycles. The particular climate model applies simplified physical parameterizations and is computationally efficient. It could thus easily be integrated in a perpetual season or advancing season configuration, as well as over many Mars years. We have assessed both high and low-frequency components of the circulation (i.e., motions having periods of Omicron(2-10 days) or greater than Omicron(10 days), respectively). Results from this investigation have explored the basic issue whether Mars' climate system is naturally 'chaotic' associated with nonlinear interactions of the large-scale circulation-regardless of any allowance for year-to-year variations in external forcing mechanisms. Titles of papers presented at scientific conferences and a manuscript to be submitted to the scientific literature are provided. An overview of a areas for further investigation is also presented.

  9. Impacts of Interannual Climate Variability on Agricultural and Marine Ecosystems

    NASA Technical Reports Server (NTRS)

    Cane, M. A.; Zebiak, S.; Kaplan, A.; Chen, D.

    2001-01-01

    The El Nino - Southern Oscillation (ENSO) is the dominant mode of global interannual climate variability, and seems to be the only mode for which current prediction methods are more skillful than climatology or persistence. The Zebiak and Cane intermediate coupled ocean-atmosphere model has been in use for ENSO prediction for more than a decade, with notable success. However, the sole dependence of its original initialization scheme and the improved initialization on wind fields derived from merchant ship observations proved to be a liability during 1997/1998 El Nino event: the deficiencies of wind observations prevented the oceanic component of the model from reaching the realistic state during the year prior to the event, and the forecast failed. Our work on the project was concentrated on the use of satellite data for improving various stages of ENSO prediction technology: model initialization, bias correction, and data assimilation. Close collaboration with other teams of the IDS project was maintained throughout.

  10. Interannual climate variability and snowpack in the western United States

    USGS Publications Warehouse

    Cayan, Daniel R.

    1996-01-01

    An important part of the water supply in the western United States is derived from runoff fed by mountain snowmelt Snow accumulation responds to both precipitation and temperature variations, and forms an interesting climatic index, since it integrates these influences over the entire late fall-spring period. Here, effects of cool season climate variability upon snow water equivalent (SWE) over the western part of the conterminous United States are examined. The focus is on measurements on/and 1 April, when snow accumulation is typically greatest. The primary data, from a network of mountainous snow courses, provides a good description of interannual fluctuations in snow accumulations, since many snow courses have records of five decades or more. For any given year, the spring SWE anomaly at a particular snow course is likely to be 25%–60% of its long-term average. Five separate regions of anomalous SWE variability are distinguished, using a rotated principal components analysis. Although effects vary with region and with elevation, in general, the anomalous winter precipitation has the strongest influence on spring SWE fluctuations. Anomalous temperature has a weaker effect overall, but it has great influence in lower elevations such as in the coastal Northwest, and during spring in higher elevations. The regional snow anomaly patterns are associated with precipitation and temperature anomalies in winter and early spring. Patterns of the precipitation, temperature, and snow anomalies extend over broad regional areas, much larger than individual watersheds. These surface anomalies are organized by the atmospheric circulation, with primary anomaly centers over the North Pacific Ocean as well as over western North America. For most of the regions, anomalously low SWE is associated with a winter circulation resembling the PNA pattern. With a strong low in the central North Pacific and high pressure over the Pacific Northwest, this pattern diverts North Pacific

  11. Seasonal divergence in the interannual responses of Northern Hemisphere vegetation activity to variations in diurnal climate.

    PubMed

    Wu, Xiuchen; Liu, Hongyan; Li, Xiaoyan; Liang, Eryuan; Beck, Pieter S A; Huang, Yongmei

    2016-01-11

    Seasonal asymmetry in the interannual variations in the daytime and nighttime climate in the Northern Hemisphere (NH) is well documented, but its consequences for vegetation activity remain poorly understood. Here, we investigate the interannual responses of vegetation activity to variations of seasonal mean daytime and nighttime climate in NH (>30 °N) during the past decades using remote sensing retrievals, FLUXNET and tree ring data. Despite a generally significant and positive response of vegetation activity to seasonal mean maximum temperature (Tmax) in ~22-25% of the boreal (>50 °N) NH between spring and autumn, spring-summer progressive water limitations appear to decouple vegetation activity from the mean summer Tmax, particularly in climate zones with dry summers. Drought alleviation during autumn results in vegetation recovery from the marked warming-induced drought limitations observed in spring and summer across 24-26% of the temperate NH. Vegetation activity exhibits a pervasively negative correlation with the autumn mean minimum temperature, which is in contrast to the ambiguous patterns observed in spring and summer. Our findings provide new insights into how seasonal asymmetry in the interannual variations in the mean daytime and nighttime climate interacts with water limitations to produce spatiotemporally variable responses of vegetation growth.

  12. Seasonal divergence in the interannual responses of Northern Hemisphere vegetation activity to variations in diurnal climate

    PubMed Central

    Wu, Xiuchen; Liu, Hongyan; Li, Xiaoyan; Liang, Eryuan; Beck, Pieter S. A.; Huang, Yongmei

    2016-01-01

    Seasonal asymmetry in the interannual variations in the daytime and nighttime climate in the Northern Hemisphere (NH) is well documented, but its consequences for vegetation activity remain poorly understood. Here, we investigate the interannual responses of vegetation activity to variations of seasonal mean daytime and nighttime climate in NH (>30 °N) during the past decades using remote sensing retrievals, FLUXNET and tree ring data. Despite a generally significant and positive response of vegetation activity to seasonal mean maximum temperature () in ~22–25% of the boreal (>50 °N) NH between spring and autumn, spring-summer progressive water limitations appear to decouple vegetation activity from the mean summer , particularly in climate zones with dry summers. Drought alleviation during autumn results in vegetation recovery from the marked warming-induced drought limitations observed in spring and summer across 24–26% of the temperate NH. Vegetation activity exhibits a pervasively negative correlation with the autumn mean minimum temperature, which is in contrast to the ambiguous patterns observed in spring and summer. Our findings provide new insights into how seasonal asymmetry in the interannual variations in the mean daytime and nighttime climate interacts with water limitations to produce spatiotemporally variable responses of vegetation growth. PMID:26751166

  13. Partitioning interannual variability in net ecosystem exchange between climatic variability and functional change.

    PubMed

    Hui, Dafeng; Luo, Yiqi; Katul, Gabriel

    2003-05-01

    Interannual variability (IAV) in net ecosystem exchange of carbon (NEE) is a critical factor in projections of future ecosystem changes. However, our understanding of IAV is limited because of the difficulty in isolating its numerous causes. We proposed that IAV in NEE is primarily caused by climatic variability, through its direct effects on photosynthesis and respiration and through its indirect effects on carbon fluxes (i.e., the parameters that govern photosynthesis and respiration), hereafter called functional change. We employed a homogeneity-of-slopes model to identify the functional change contributing to IAV in NEE and nighttime ecosystem respiration (RE). The model uses multiple regression analysis to relate NEE and RE with climatic variables for individual years and for all years. If the use of different slopes for each year significantly improves the model fitting compared to the use of one slope for all years, we consider that functional change exists, at least on annual time scales. With the functional change detected, we then partition the observed variation in NEE or RE to four components, namely, the functional change, the direct effect of interannual climatic variability, the direct effect of seasonal climatic variation, and random error. Application of this approach to a data set collected at the Duke Forest AmeriFlux site from August 1997 to December 2001 indicated that functional change, interannual climatic variability, seasonal climatic variation and random error explained 9.9, 8.9, 59.9 and 21.3%, respectively, of the observed variation in NEE and 13.1, 5.0, 38.1 and 43.8%, respectively, of the observed variation in RE.

  14. Exchange of carbon dioxide by a deciduous forest: Response to interannual climate variability

    SciTech Connect

    Goulden, M.L.; Munger, J.W.; Fan, S.M.; Daube, B.C.; Wofsy, S.C.

    1996-03-15

    The annual net uptake of CO{sub 2} by a deciduous forest in New England varied from 1.4 to 2.8 metric tons of carbon per hectare between 1991 and 1995. Carbon sequestration was higher than average in 1991 because of increased photosynthesis and in 1995 because of decreased respiration. Interannual shifts in photosynthesis were associated with the timing of leaf expansion and senescence. Shifts in annual respiration were associated with anomalies in soil temperature, deep snow in winter, and drought in summer. If this ecosystem is typical of northern biomes, interannual climate variations on seasonal time scales may modify annual CO{sub 2} exchange in the Northern Hemisphere by 1 gigaton of carbon or more each year. 26 refs., 4 figs., 1 tab.

  15. Interannual climate variability change during the Medieval Climate Anomaly and Little Ice Age in PMIP3 last millennium simulations

    NASA Astrophysics Data System (ADS)

    Yang, Kaiqing; Jiang, Dabang

    2017-04-01

    In this study, we analyzed numerical experiments undertaken by 10 climate models participating in PMIP3 (Paleoclimate Modelling Intercomparison Project Phase 3) to examine the changes in interannual temperature variability and coefficient of variation (CV) of interannual precipitation in the warm period of the Medieval Climate Anomaly (MCA) and the cold period of the Little Ice Age (LIA). With respect to the past millennium period, the MCA temperature variability decreases by 2.0% on average over the globe, and most of the decreases occur in low latitudes. In the LIA, temperature variability increases by a global average of 0.6%, which occurs primarily in the high latitudes of Eurasia and the western Pacific. For the CV of interannual precipitation, regional-scale changes are more significant than changes at the global scale, with a pattern of increased (decreased) CV in the midlatitudes of Eurasia and the northwestern Pacific in the MCA (LIA). The CV change ranges from -7.0% to 4.3% (from -6.3% to 5.4%), with a global average of -0.5% (-0.07%) in the MCA (LIA). Also, the variability changes are considerably larger in December-January-February with respect to both temperature and precipitation.

  16. Interannual water-level fluctuations and the vegetation of prairie potholes: Potential impacts of climate change

    USGS Publications Warehouse

    van der Valk, Arnold; Mushet, David M.

    2016-01-01

    Mean water depth and range of interannual water-level fluctuations over wet-dry cycles in precipitation are major drivers of vegetation zone formation in North American prairie potholes. We used harmonic hydrological models, which require only mean interannual water depth and amplitude of water-level fluctuations over a wet–dry cycle, to examine how the vegetation zones in a pothole would respond to small changes in water depth and/or amplitude of water-level fluctuations. Field data from wetlands in Saskatchewan, North Dakota, and South Dakota were used to parameterize harmonic models for four pothole classes. Six scenarios in which small negative or positive changes in either mean water depth, amplitude of interannual fluctuations, or both, were modeled to predict if they would affect the number of zones in each wetland class. The results indicated that, in some cases, even small changes in mean water depth when coupled with a small change in amplitude of water-level fluctuations can shift a prairie pothole wetland from one class to another. Our results suggest that climate change could alter the relative proportion of different wetland classes in the prairie pothole region.

  17. Formation mechanism for the amplitude of interannual climate variability in subtropical northern hemisphere: relative contributions from the zonal asymmetric mean state and the interannual variability of SST

    NASA Astrophysics Data System (ADS)

    He, Chao; Lin, Ailan; Gu, Dejun; Li, Chunhui; Zheng, Bin

    2017-01-01

    The Amplitude Interannual climate Variability (AIV) differs among the subtropical northern hemisphere, and the Western North Pacific (WNP) was claimed to exhibit the largest AIV. The robustness of the AIV pattern is investigated in this study with different atmospheric variables from multiple datasets. As consistently shown by the interannual variance patterns of precipitation and circulation, the AIV over subtropical northern hemisphere closely follows the mean state of precipitation, where higher (lower) AIV is located at moister (drier) regions. The largest AIV is seen over the broad area from South Asia to WNP, followed by a secondary local maximum over the Gulf of Mexico. To further investigate the formation mechanism for the AIV pattern, numerical simulations are performed by Community Atmosphere Model version 4 (CAM4). The zonal asymmetry of AIV is reduced if the interannual SST variability is removed, and it almost disappears if the zonal asymmetry of SST mean state is removed. The results suggest that the zonal asymmetric AIV pattern primarily originates from the zonal asymmetric SST mean state, and it is amplified by the interannual SST variability. The atmospheric convection-circulation feedback plays a key role in connecting the AIV with the mean state precipitation. In both observation and CAM4 simulations, stronger (weaker) convection-circulation feedback is seen in moister (drier) regions. By modulating the mean state precipitation and the associated intensity of convection-circulation feedback, the zonal asymmetric SST mean state accounts for the zonal asymmetry of AIV in the subtropical northern hemisphere.

  18. Interannual and spatial variability of maple syrup yield as related to climatic factors.

    PubMed

    Duchesne, Louis; Houle, Daniel

    2014-01-01

    Sugar maple syrup production is an important economic activity for eastern Canada and the northeastern United States. Since annual variations in syrup yield have been related to climate, there are concerns about the impacts of climatic change on the industry in the upcoming decades. Although the temporal variability of syrup yield has been studied for specific sites on different time scales or for large regions, a model capable of accounting for both temporal and regional differences in yield is still lacking. In the present study, we studied the factors responsible for interregional and interannual variability in maple syrup yield over the 2001-2012 period, by combining the data from 8 Quebec regions (Canada) and 10 U.S. states. The resulting model explained 44.5% of the variability in yield. It includes the effect of climatic conditions that precede the sapflow season (variables from the previous growing season and winter), the effect of climatic conditions during the current sapflow season, and terms accounting for intercountry and temporal variability. Optimal conditions for maple syrup production appear to be spatially restricted by less favourable climate conditions occurring during the growing season in the north, and in the south, by the warmer winter and earlier spring conditions. This suggests that climate change may favor maple syrup production northwards, while southern regions are more likely to be negatively affected by adverse spring conditions.

  19. Interannual and spatial variability of maple syrup yield as related to climatic factors

    PubMed Central

    Houle, Daniel

    2014-01-01

    Sugar maple syrup production is an important economic activity for eastern Canada and the northeastern United States. Since annual variations in syrup yield have been related to climate, there are concerns about the impacts of climatic change on the industry in the upcoming decades. Although the temporal variability of syrup yield has been studied for specific sites on different time scales or for large regions, a model capable of accounting for both temporal and regional differences in yield is still lacking. In the present study, we studied the factors responsible for interregional and interannual variability in maple syrup yield over the 2001–2012 period, by combining the data from 8 Quebec regions (Canada) and 10 U.S. states. The resulting model explained 44.5% of the variability in yield. It includes the effect of climatic conditions that precede the sapflow season (variables from the previous growing season and winter), the effect of climatic conditions during the current sapflow season, and terms accounting for intercountry and temporal variability. Optimal conditions for maple syrup production appear to be spatially restricted by less favourable climate conditions occurring during the growing season in the north, and in the south, by the warmer winter and earlier spring conditions. This suggests that climate change may favor maple syrup production northwards, while southern regions are more likely to be negatively affected by adverse spring conditions. PMID:24949244

  20. Effect of interannual climate variability on carbon storage in Amazonian ecosystems

    USGS Publications Warehouse

    Tian, H.; Melillo, J.M.; Kicklighter, D.W.; McGuire, David A.; Helfrich, J. V. K.; Moore, B.; Vorosmarty, C.J.

    1998-01-01

    The Amazon Basin contains almost one-half of the world's undisturbed tropical evergreen forest as well as large areas of tropical savanna. The forests account for about 10 per cent of the world's terrestrial primary productivity and for a similar fraction of the carbon stored in land ecosystems, and short-term field measurements suggest that these ecosystems are globally important carbon sinks. But tropical land ecosystems have experienced substantial interannual climate variability owing to frequent El Nino episodes in recent decades. Of particular importance to climate change policy is how such climate variations, coupled with increases in atmospheric CO2 concentration, affect terrestrial carbon storage. Previous model analyses have demonstrated the importance of temperature in controlling carbon storage. Here we use a transient process-based biogeochemical model of terrestrial ecosystems to investigate interannual variations of carbon storage in undisturbed Amazonian ecosystems in response to climate variability and increasing atmospheric CO2 concentration during the period 1980 to 1994. In El Nino years, which bring hot, dry weather to much of the Amazon region, the ecosystems act as a source of carbon to the atmosphere (up to 0.2 petagrams of carbon in 1987 and 1992). In other years, these ecosystems act as a carbon sink (up to 0.7 Pg C in 1981 and 1993). These fluxes are large; they compare to a 0.3 Pg C per year source to the atmosphere associated with deforestation in the Amazon Basin in the early 1990s. Soil moisture, which is affected by both precipitation and temperature, and which affects both plant and soil processes, appears to be an important control on carbon storage.

  1. Interannual to multidecadal climate forcings on groundwater resources of the U.S. West Coast

    USGS Publications Warehouse

    Velasco, Elzie M; Gurdak, Jason J.; Dickinson, Jesse; Ferre, T.P.A; Corona, Claudia

    2016-01-01

    Study regionThe U.S. West Coast, including the Pacific Northwest and California Coastal Basins aquifer systems.Study focusGroundwater response to interannual to multidecadal climate variability has important implications for security within the water–energy–food nexus. Here we use Singular Spectrum Analysis to quantify the teleconnections between AMO, PDO, ENSO, and PNA and precipitation and groundwater level fluctuations. The computer program DAMP was used to provide insight on the influence of soil texture, depth to water, and mean and period of a surface infiltration flux on the damping of climate signals in the vadose zone.New hydrological insights for the regionWe find that PDO, ENSO, and PNA have significant influence on precipitation and groundwater fluctuations across a north-south gradient of the West Coast, but the lower frequency climate modes (PDO) have a greater influence on hydrologic patterns than higher frequency climate modes (ENSO and PNA). Low frequency signals tend to be preserved better in groundwater fluctuations than high frequency signals, which is a function of the degree of damping of surface variable fluxes related to soil texture, depth to water, mean and period of the infiltration flux. The teleconnection patterns that exist in surface hydrologic processes are not necessarily the same as those preserved in subsurface processes, which are affected by damping of some climate variability signals within infiltrating water.

  2. Climate-driven interannual variability of water scarcity in food production: a global analysis

    NASA Astrophysics Data System (ADS)

    Kummu, M.; Gerten, D.; Heinke, J.; Konzmann, M.; Varis, O.

    2013-06-01

    Interannual climatic and hydrologic variability has been substantial during the past decades in many regions. While climate variability and its impacts on precipitation and soil moisture have been rather intensively studied, less is known on its impacts on freshwater availability and further implications for global food production. In this paper we quantify effects of hydroclimatic variability on global "green" and "blue" water availability and demand in agriculture. Analysis is based on climate forcing data for the past 30 yr with demography, diet composition and land use fixed to constant reference conditions. We thus assess how observed interannual hydroclimatic variability impacts on the ability of food production units (FPUs) to produce a given diet for their inhabitants, here focused on a benchmark for hunger alleviation (3000 kilocalories per capita per day, with 80% vegetal food and 20% animal products). We applied the LPJmL vegetation and hydrology model to calculate spatially explicitly the variation in green-blue water availability and the water requirements to produce that very diet. An FPU was considered water scarce if its water availability was not sufficient to produce the diet (neglecting trade from elsewhere, i.e. assuming food self-sufficiency). We found that altogether 24% of the global population lives in areas under chronic scarcity (i.e. water is scarce every year) while an additional 19% live under occasional water scarcity (i.e. water is scarce in some years). Of these 2.6 billion people under some degree of scarcity, 55% would have to rely on international trade to reach the reference diet while for 24% domestic trade would be enough (assuming present cropland extent and management). For the remaining 21% of population under scarcity, local food storage and/or intermittent trade would be enough secure the reference diet over the occasional dry years.

  3. Climate-driven interannual variability of water scarcity in food production potential: a global analysis

    NASA Astrophysics Data System (ADS)

    Kummu, M.; Gerten, D.; Heinke, J.; Konzmann, M.; Varis, O.

    2014-02-01

    Interannual climatic and hydrologic variability has been substantial during the past decades in many regions. While climate variability and its impacts on precipitation and soil moisture have been studied intensively, less is known on subsequent implications for global food production. In this paper we quantify effects of hydroclimatic variability on global "green" and "blue" water availability and demand in global agriculture, and thus complement former studies that have focused merely on long-term averages. Moreover, we assess some options to overcome chronic or sporadic water scarcity. The analysis is based on historical climate forcing data sets over the period 1977-2006, while demography, diet composition and land use are fixed to reference conditions (year 2000). In doing so, we isolate the effect of interannual hydroclimatic variability from other factors that drive food production. We analyse the potential of food production units (FPUs) to produce a reference diet for their inhabitants (3000 kcal cap-1 day-1, with 80% vegetal food and 20% animal products). We applied the LPJmL vegetation and hydrology model to calculate the variation in green-blue water availability and the water requirements to produce that very diet. An FPU was considered water scarce if its water availability was not sufficient to produce the diet (i.e. assuming food self-sufficiency to estimate dependency on trade from elsewhere). We found that 24% of the world's population lives in chronically water-scarce FPUs (i.e. water is scarce every year), while an additional 19% live under occasional water scarcity (water is scarce in some years). Among these 2.6 billion people altogether, 55% would have to rely on international trade to reach the reference diet, while for 24% domestic trade would be enough. For the remaining 21% of the population exposed to some degree of water scarcity, local food storage and/or intermittent trade would be enough to secure the reference diet over the

  4. Regional climate extremes in Northern Eurasia associated with atmospheric blockings: Interannual variations and tendencies of change

    NASA Astrophysics Data System (ADS)

    Mokhov, I.; Akperov, M.; Lupo, A. R.; Chernokulsky, A. V.; Timazhev, A.

    2011-12-01

    Large regional climate anomalies associated with atmospheric blockings have been noted during last years in Northern Eurasia. Impact of blockings is exhibited in such extremes as heat and cold waves, droughts, and forest fires. In order to detect changes in the blocking activity characteristics an analysis of different data for the Northern Hemisphere with the use of various methods for blockings detection was carried out. In particular, the data for 500 hPa geopotential from the NCEP/NCAR Reanalysis 1 (1948-2010) and NOAA-CIRES 20th Century Reanalysis v2 (1871-2008) have been used as well as climate model simulations for the 20th and 21st centuries with anthropogenic forcing. Special attention is paid to the analysis of extreme dry conditions in the Northern Eurasia regions and to the 2010 Russian heat wave associated to atmospheric blockings with the use observational data (1891-2010) for surface air temperature, precipitation and different indices for the drought conditions. Tendencies of change and interannual variations are analyzed with an assessment of effects of El-Nino/La-Nina phenomena. Possibility of intensification of blocking-associated climate impacts under global warming is discussed. Changes of blocking characteristics and associated regional climate anomalies in the 21st century based on model simulations with anthropogenic scenarios are analyzed.

  5. Marine climate influences on interannual variability of tropical cyclones in the eastern Caribbean: 1979-2008

    NASA Astrophysics Data System (ADS)

    Jury, Mark R.

    2015-04-01

    Interannual variability of tropical cyclones (TCs) in the eastern Caribbean is studied using MIT-Hurdat fields during the July-October season from 1979 to 2008. TC intensity shows local climate sensitivity particularly for upper ocean currents, salinity and mixed-layer depth, and 200-850 mb wind shear. Remote influences from the Southern Oscillation, Saharan dust, and the South American monsoon are also identified as important. Ocean currents diminish along the coast of South America, so interbasin transfer between the North Brazil and Caribbean Currents declines in seasons of frequent and intense TCs. This is related to a dipole pattern in the sea surface height formed mainly by reduced trade wind upwelling northeast of Venezuela. A low-salinity plume from the Orinoco River spreads across the eastern Caribbean. It is the weaker currents and shallower mixed layer that conspire with surplus heat to build thermodynamic energy available for TC intensification.

  6. Seasonal and interannual variability of climate and vegetation indices across the Amazon.

    PubMed

    Brando, Paulo M; Goetz, Scott J; Baccini, Alessandro; Nepstad, Daniel C; Beck, Pieter S A; Christman, Mary C

    2010-08-17

    Drought exerts a strong influence on tropical forest metabolism, carbon stocks, and ultimately the flux of carbon to the atmosphere. Satellite-based studies have suggested that Amazon forests green up during droughts because of increased sunlight, whereas field studies have reported increased tree mortality during severe droughts. In an effort to reconcile these apparently conflicting findings, we conducted an analysis of climate data, field measurements, and improved satellite-based measures of forest photosynthetic activity. Wet-season precipitation and plant-available water (PAW) decreased over the Amazon Basin from 1996-2005, and photosynthetically active radiation (PAR) and air dryness (expressed as vapor pressure deficit, VPD) increased from 2002-2005. Using improved enhanced vegetation index (EVI) measurements (2000-2008), we show that gross primary productivity (expressed as EVI) declined with VPD and PAW in regions of sparse canopy cover across a wide range of environments for each year of the study. In densely forested areas, no climatic variable adequately explained the Basin-wide interannual variability of EVI. Based on a site-specific study, we show that monthly EVI was relatively insensitive to leaf area index (LAI) but correlated positively with leaf flushing and PAR measured in the field. These findings suggest that production of new leaves, even when unaccompanied by associated changes in LAI, could play an important role in Basin-wide interannual EVI variability. Because EVI variability was greatest in regions of lower PAW, we hypothesize that drought could increase EVI by synchronizing leaf flushing via its effects on leaf bud development.

  7. Interannual to Multidecadal Climate Variability and Groundwater Resources of the Western United States

    NASA Astrophysics Data System (ADS)

    Gurdak, J. J.; Kuss, A. M.

    2011-12-01

    Climate variability and change have important implications for groundwater recharge, discharge, contaminant transport, and resource sustainability. Reliable predictions of groundwater sustainability due to climate change will require improved understanding of the effects of global scale atmosphere-ocean climate oscillations on interannual to multidecadal timescales. Climate variability on these timescales partially controls precipitation, air temperature, drought, evapotranspiration, streamflow, recharge, and mobilization of subsurface-chemical reservoirs. Climate variability can augment or diminish human stresses on groundwater, and the responses in storage can be dramatic when different climate cycles lie coincident in a positive or negative phase of variability. Thus, understanding climate variability has particular relevance for management decisions during drought and for water resources close to the limits of sustainability. Major findings will be presented from a national scale study of climate variability on recharge rates and groundwater levels, and will highlight regional aquifers of the western United States, including the Basin and Range (700,000 km2), Central Valley (52,000 km2), High Plains (450,000 km2), and Mississippi Embayment (181,000 km2) aquifer systems. Using singular spectrum analysis, the groundwater pumping signal was removed and natural variations were identified in groundwater levels as partially coincident with the El Niño/Southern Oscillation (ENSO) (2-6 year cycle), North Atlantic Oscillation (3-6 year cycle), Pacific Decadal Oscillation (PDO) (10-25 year cycle), and Atlantic Multidecadal Oscillation (AMO) (50-80 year cycle). The PDO was the most significant contributor to recharge and groundwater level fluctuations in most aquifers. In the Central Valley and the Basin and Range, the PDO contributes to the greatest amount of variance (ranging from 13.6-83%) in all precipitation and groundwater level time series, with moderate to strong

  8. Storm-tracks interannual variability and large-scale climate modes

    NASA Astrophysics Data System (ADS)

    Liberato, Margarida L. R.; Trigo, Isabel F.; Trigo, Ricardo M.

    2013-04-01

    In this study we focus on the interannual variability and observed changes in northern hemisphere mid-latitude storm-tracks and relate them to large scale atmospheric circulation variability modes. Extratropical storminess, cyclones dominant paths, frequency and intensity have long been the object of climatological studies. The analysis of storm characteristics and historical trends presented here is based on the cyclone detecting and tracking algorithm first developed for the Mediterranean region (Trigo et al. 1999) and recently extended to a larger Euro-Atlantic region (Trigo 2006). The objective methodology, which identifies and follows individual lows as minima in SLP fields, fulfilling a set of conditions regarding the central pressure and the pressure gradient, is applied to the northern hemisphere 6-hourly geopotential data at 1000 hPa from the 20th Century Reanalyses (20CRv2) project and from reanalyses datasets provided by the European Centre for Medium-Range Weather Forecasts (ECMWF): ERA-40 and ERA Interim reanalyses. First, we assess the interannual variability and cyclone frequency trends for each of the datasets, for the 20th century and for the period between 1958 and 2002 using the highest spatial resolution available (1.125° x 1.125°) from the ERA-40 data. Results show that winter variability of storm paths, cyclone frequency and travel times is in agreement with the reported variability in a number of large-scale climate patterns (including the North Atlantic Oscillation, the East Atlantic Pattern and the Scandinavian Pattern). In addition, three storm-track databases are built spanning the common available extended winter seasons from October 1979 to March 2002. Although relatively short, this common period allows a comparison of systems represented in reanalyses datasets with distinct horizontal resolutions. This exercise is mostly focused on the key areas of cyclogenesis and cyclolysis and main cyclone characteristics over the northern

  9. The Role of Global Hydrologic Processes in Interannual and Long-Term Climate Variability

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.

    1997-01-01

    The earth's climate and its variability is linked inextricably with the presence of water on our planet. El Nino / Southern Oscillation-- the major mode of interannual variability-- is characterized by strong perturbations in oceanic evaporation, tropical rainfall, and radiation. On longer time scales, the major feedback mechanism in CO2-induced global warming is actually that due to increased water vapor holding capacity of the atmosphere. The global hydrologic cycle effects on climate are manifested through influence of cloud and water vapor on energy fluxes at the top of atmosphere and at the surface. Surface moisture anomalies retain the "memory" of past precipitation anomalies and subsequently alter the partitioning of latent and sensible heat fluxes at the surface. At the top of atmosphere, water vapor and cloud perturbations alter the net amount of radiation that the earth's climate system receives. These pervasive linkages between water, radiation, and surface processes present major complexities for observing and modeling climate variations. Major uncertainties in the observations include vertical structure of clouds and water vapor, surface energy balance, and transport of water and heat by wind fields. Modeling climate variability and change on a physical basis requires accurate by simplified submodels of radiation, cloud formation, radiative exchange, surface biophysics, and oceanic energy flux. In the past, we m safely say that being "data poor' has limited our depth of understanding and impeded model validation and improvement. Beginning with pre-EOS data sets, many of these barriers are being removed. EOS platforms with the suite of measurements dedicated to specific science questions are part of our most cost effective path to improved understanding and predictive capability. This talk will highlight some of the major questions confronting global hydrology and the prospects for significant progress afforded by EOS-era measurements.

  10. Global analysis of climate-driven interannual variability of food production and related water scarcity

    NASA Astrophysics Data System (ADS)

    Kummu, Matti; Gerten, Dieter; Heinke, Jens; Konzmann, Markus; Varis, Olli

    2014-05-01

    Interannual climatic and hydrologic variability has been substantial during the past decades in many regions. While climate variability and its impacts on precipitation and soil moisture have been studied intensively, less is known on subsequent implications for global food production. In this study we quantify effects of hydroclimatic variability on global "green" and "blue" water availability and demand in global agriculture, and thus complement former studies that have focused merely on long-term averages. We further quantify some options to overcome food deficit due to chronic or sporadic water scarcity. We found that 24% of the world's population lives in chronically water scare food production units (FPUs) (i.e. water is scarce every year), while an additional 19% live under occasional water scarcity (water is scarce in some years). Among these 2.6 billion people altogether, 55% would have to rely on international trade to reach the reference diet, while for 24% domestic trade would be enough. For the remaining 21% of population exposed to some degree of water scarcity, local food storage and/or intermittent trade would be enough to secure the reference diet over the occasional dry years. The analysis is based on historical climate forcing dataset over the period 1977-2007, while demography, diet composition and land use are fixed to reference conditions (year 2000). In so doing, we isolate the effect of interannual hydroclimatic variability from other factors that drive food production. We analyse the potential of FPUs to produce a reference diet for their inhabitants (3,000 kilocalories per capita per day, with 80% vegetal food and 20% animal products). The LPJmL vegetation and hydrology model was used to calculate spatially and explicitly the variation in food production, green-blue water availability and the water requirements to produce that very diet. An FPU was considered water scarce if its water availability was not sufficient to produce the diet (i

  11. Evaluation of Canadian Seasonal to Interannual Prediction System: seasonal hindcasts of the recent past climate.

    NASA Astrophysics Data System (ADS)

    Markovic, M.

    2015-12-01

    Canadian Seasonal to Interannual Prediction System (CanSIPS) has been operationally active within the Meteorological Service of Canada since the year of 2011. This coupled (atmosphere-land-ocean) system is in charge of producing seasonal forecasts of near surface temperature and precipitation for the following 12 months with respect to the forecast onset. CanSIPS comprises two coupled atmosphere-land-ocean models: CanCM3 and CanCM4 developed in Canadian Centre for Climate Modelling and Analysis. Each model produces ten-member ensemble forecasts which generate twenty member ensemble predictions. In this work we evaluate seasonal hindcasts of the recent past climate (1981-2010) simulated by the CanSIPS system. The importance of such evaluation stems from the fact that seasonal hindcasts can be used to calibrate the results of the seasonal predictions. Calibrated forecasts have in general more skill compared to the raw predictions. Moreover, verification of seasonal hindcasts enables an estimation of the expected performance of the prediction system over various regions and seasons (i.e. expected skill maps). Evaluation will be presented against reanalysis data. Near surface temperature and precipitation will be assessed over different geographical locations and various lead times.

  12. Interannual Variations in the South Asian Haze : Implications to Climate Variability Including ENSO

    NASA Astrophysics Data System (ADS)

    Ramanathan, V.; Chung, C. E.

    2002-05-01

    Aerosols are regionally concentrated and are subject to large temporal variations, even on inter-annual time scales. The fundamental reasons for this large variability are the short life times of aerosols and the important role of transport in regulating their regional concentrations. In this study, we focus on the observed large interannual variability of the South Asian haze, estimate the corresponding variations in its radiative forcing, and use a general circulation model to study the impact on global climate variability. The South Asian haze is wide spread haze, covering most of the North Indian ocean including the Arabian sea and the bay of Bengal. The southernmost extent of the haze varies year to year from about 10 S to about 5 N. In order to understand the impact of this interannual variation in the haze forcing, we conducted two numerical experiments with two extreme locations of the forcing: 1) extended haze forcing (EHF) and 2) shrunk haze forcing (SHF). The former has the forcing applied northward of 10oS and the latter confined top regions north of equator, and these two cases represent two extreme phases of the satellite retrieved AODs (Aerosol Optical Depths) over the Indian Ocean. Each of the two numerical experiments was implemented into the NCAR/CCM3 with the climatological (but seasonally varying) SST to estimate the climate sensitivity to the area of the aerosol forcing. Over India where the forcing is centered, the simulated climate changes are very similar between the two experiments. In remote regions however, the responses differ substantially. First, both experiments simulate the wintertime drought over southwest Asia, with the extended forcing simulating far more severe drought. Second, the extended forcing significantly suppresses convection in the western equatorial Pacific during the boreal wintertime, and the shrunk forcing leads to much less suppression. Since the western Pacific convection suppression would relax the trade winds

  13. Intraseasonal-to-interannual variability of the Indian Monsoon: the present climate and future projections of climate change

    NASA Astrophysics Data System (ADS)

    Carvalho, L. V.; Jones, C.; Cannon, F.

    2014-12-01

    The Asia Monsoon is among Earth's most intriguing and spectacular phenomena. The Indian Monsoon System (IMS) is a regional manifestation this continental-scale phenomenon with complex characteristics and predictive challenges. India exhibits one of the largest rates of population growth that relies on IMS cycle for water supply. Thus, understanding the temporal variability of the IMS is essential to realistically predict the impacts of climate change on Asia's water resources and food security. Here we investigate intraseasonal-to-interannual variability of the IMS in the climate of the 20th century using the Climate Forecast System Reanalysis (CFSR) and examine future scenarios of climate change using the high spatial resolution models of the Coupled Model Intercomparison Project Phase 5 (CMIP5) project. IMS is characterized with a large-scale index continuous in time and obtained by performing combined EOF analysis (CEOF) of variables that characterize the monsoon cycle: precipitation, low level circulation at 10 m, specific humidity and temperature at 2m. CFSR is used to derive the index (1979-2013). Projections of the CEOF onto the tropical rainfall measuring mission (TRMM) indicate that the first CEOF captures the large-scale features of the South and East Asia Monsoon. The second CEOF is associated with the IMS and its time coefficient is used as large-scale index for the IMS (LIMS). LIMS realistically defines IMS onset and withdrawal, and its amplitude associates with total seasonal precipitation. Moreover, the spectral analysis of the ISMI shows peaks on intraseasonal timescales that are related to IMS's active and break phases. Moreover, we demonstrate that LIMS identifies the interannual variability of IMS and can be used to investigate floods and droughts that have occurred over India. Similar approach is used to investigate the skill of the CMIP5 models in realistically simulating active and break phases of the IMS in the 'historic' run (1951-2005). We

  14. The influence of inter-annually varying albedo on regional climate and drought

    NASA Astrophysics Data System (ADS)

    Meng, X. H.; Evans, J. P.; McCabe, M. F.

    2014-02-01

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a

  15. The influence of inter-annually varying albedo on regional climate and drought

    NASA Astrophysics Data System (ADS)

    Meng, X. H.; Evans, J. P.; McCabe, M. F.

    2013-05-01

    Albedo plays an important role in land-atmosphere interactions and local climate. This study presents the impact on simulating regional climate, and the evolution of a drought, when using the default climatological albedo as is usually done in regional climate modelling, or using the actual observed albedo which is rarely done. Here, time-varying satellite derived albedo data is used to update the lower boundary condition of the Weather Research and Forecasting regional climate model in order to investigate the influence of observed albedo on regional climate simulations and also potential changes to land-atmosphere feedback over south-east Australia. During the study period from 2000 to 2008, observations show that albedo increased with an increasingly negative precipitation anomaly, though it lagged precipitation by several months. Compared to in-situ observations, using satellite observed albedo instead of the default climatological albedo provided an improvement in the simulated seasonal mean air temperature. In terms of precipitation, both simulations reproduced the drought that occurred from 2002 through 2006. Using the observed albedo produced a drier simulation overall. During the onset of the 2002 drought, albedo changes enhanced the precipitation reduction by 20 % on average, over locations where it was active. The area experiencing drought increased 6.3 % due to the albedo changes. Two mechanisms for albedo changes to impact land-atmosphere drought feedback are investigated. One accounts for the increased albedo, leading to reduced turbulent heat flux and an associated decrease of moist static energy density in the planetary boundary layer; the other considers that enhanced local radiative heating, due to the drought, favours a deeper planetary boundary layer, subsequently decreasing the moist static energy density through entrainment of the free atmosphere. Analysis shows that drought related large-scale changes in the regional climate favour a

  16. 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

  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. Climate extremes dominating seasonal and interannual variations in carbon export from the Mississippi River Basin

    NASA Astrophysics Data System (ADS)

    Tian, Hanqin; Ren, Wei; Yang, Jia; Tao, Bo; Cai, Wei-Jun; Lohrenz, Steven E.; Hopkinson, Charles S.; Liu, Mingliang; Yang, Qichun; Lu, Chaoqun; Zhang, Bowen; Banger, Kamaljit; Pan, Shufen; He, Ruoying; Xue, Zuo

    2015-09-01

    Knowledge about the annual and seasonal patterns of organic and inorganic carbon (C) exports from the major rivers of the world to the coastal ocean is essential for our understanding and potential management of the global C budget so as to limit anthropogenic modification of global climate. Unfortunately our predictive understanding of what controls the timing, magnitude, and quality of C export is still rudimentary. Here we use a process-based coupled hydrologic/ecosystem biogeochemistry model (the Dynamic Land Ecosystem Model) to examine how climate variability and extreme events, changing land use, and atmospheric chemistry have affected the annual and seasonal patterns of C exports from the Mississippi River basin to the Gulf of Mexico. Our process-based simulations estimate that the average annual exports of dissolved organic C (DOC), particulate organic C (POC), and dissolved inorganic C (DIC) in the 2000s were 2.6 ± 0.4 Tg C yr-1, 3.4 ± 0.3 Tg C yr-1, and 18.8 ± 3.4 Tg C yr-1, respectively. Although land use change was the most important agent of change in C export over the past century, climate variability and extreme events (such as flooding and drought) were primarily responsible for seasonal and interannual variations in C export from the basin. The maximum seasonal export of DIC occurred in summer while for DOC and POC the maximum occurred in winter. Relative to the 10 year average (2001-2010), our modeling analysis indicates that the years of maximal and minimal C export cooccurred with wet and dry years (2008: 32% above average and 2006: 32% below average). Given Intergovernmental Panel on Climate Change-predicted changes in climate variability and the severity of rain events and droughts of wet and dry years for the remainder of the 21st century, our modeling results suggest major changes in the riverine link between the terrestrial and oceanic realms, which are likely to have a major impact on C delivery to the coastal ocean.

  19. Diagnostics of Interannual-to-Interdecadal Climate and Streamflow Variability: Applications to Reservoir Management over NW India

    NASA Astrophysics Data System (ADS)

    Robertson, A. W.; Cook, E. R.; Ghil, M.; Greene, A. M.; Kondrashov, D. A.; Lall, U.; Lu, M.

    2013-12-01

    Multi-year storage reservoirs must be managed in the face of weather and climate variability across time scales ranging from daily weather to interannual climate. While seasonal climate may contain a predictable component associated with the El Nino-Southern Oscillation (ENSO), longer time scales are not yet usefully predictable, nor is the interannual-to-interdecadal power spectrum well estimated from observed data. In addition, climate simulations from general circulation models (GCMs) are often lacking in their ability to generate realistic hydroclimate variability across time scales, especially at small spatial scales. These issues are critical for climate change adaptation planning in water management, where realistic estimates of climate and stream flow variability are required. For the Bhakra reservoir in NW India, we develop estimates of climate and stream flow variability, including the interannual-to-interdecadal power spectrum, based on (1) instrumental stream flow records of the Sutlej river, 1963-2010; (2) tree ring reconstructions of the Sutlej flow back to 1321; and (3) multi-century control simulations of precipitation-minus-evaporation made with several coupled ocean-atmosphere GCMs archived in the IPCC CMIP5 database. By comparing these observed, paleo-proxy, and GCM-based estimates, we shed light on the ability of GCMs to simulate realistic hydroclimate variability over the Indus basin, as well as on the nature of tree-ring based streamflow reconstructions. In addition to these estimates of the variability spectrum, we explore the use of a nonlinear, multi-level stochastic polynomial inverse model to bridge between these different datasets.

  20. Potential impacts of a future Grand Solar Minimum on decadal regional climate change and interannual hemispherical climate variability

    NASA Astrophysics Data System (ADS)

    Spiegl, Tobias; Langematz, Ulrike

    2016-04-01

    Grand Solar Minimum under RCP6.0 conditions. The results obtained were compared to a RCP6.0 simulation that was carried out using the CCMI recommendations for a 21st century solar forcing. We used the ECHAM/MESSy Atmospheric Chemistry (EMAC) chemistry-climate model that incorporates interactive ozone chemistry, a high-resolution shortwave radiation scheme, a high model top (0.01 hPa) and is coupled to a 3D ocean general circulation model. We focused on the regional responses to a future Grand Solar Minimum and interannual variability patterns (i.e. the Northern and Southern Annular Mode (NAM/SAM)).

  1. Upper air relaxation in regional climate model improves resolved interannual variability of the surface mass balance of Antarctica

    NASA Astrophysics Data System (ADS)

    van de Berg, Willem Jan; Medley, Brooke; van Meijgaard, Erik

    2015-04-01

    The surface mass balance (SMB) determines the variability of the mass balance of the Antarctic Ice sheet on sub-decadal timescales. Since continent-wide SMB cannot be measured, it must be modeled and regional climate models (RCMs) generally outperform global reanalyses in the representation of total mass flux and the spatial distribution of SMB. However, if RCMs are only forced with reanalysis on their lateral boundaries, the representation of the interannual variability of SMB deteriorates significantly. In this study we show how to improve the resolved interannual variability in RCM modeled SMB. For this purpose we use annual SMB observations in the Thwaites drainage basin in Antarctica derived from airborne radar reflections and the RCM RACMO2. RACMO2, driven by ERA-Interim, better represents the mean spatial SMB pattern in this basin than ERA-Interim. However, without relaxation in the interior, RACMO2 poorly resolves the observed interannual SMB variability. If we gently relax the temperature and wind field in the upper atmosphere in RACMO2 to ERA-Interim, RACMO2 gets the best of both. Upper air relaxation little changes the mean SMB and spatial pattern compared to the original RACMO2 output, but allows RACMO2 to resolve the observed interannual SMB as good as ERA-Interim.

  2. Constructing the reduced dynamical models of interannual climate variability from spatial-distributed time series

    NASA Astrophysics Data System (ADS)

    Mukhin, Dmitry; Gavrilov, Andrey; Loskutov, Evgeny; Feigin, Alexander

    2016-04-01

    We suggest a method for empirical forecast of climate dynamics basing on the reconstruction of reduced dynamical models in a form of random dynamical systems [1,2] derived from observational time series. The construction of proper embedding - the set of variables determining the phase space the model works in - is no doubt the most important step in such a modeling, but this task is non-trivial due to huge dimension of time series of typical climatic fields. Actually, an appropriate expansion of observational time series is needed yielding the number of principal components considered as phase variables, which are to be efficient for the construction of low-dimensional evolution operator. We emphasize two main features the reduced models should have for capturing the main dynamical properties of the system: (i) taking into account time-lagged teleconnections in the atmosphere-ocean system and (ii) reflecting the nonlinear nature of these teleconnections. In accordance to these principles, in this report we present the methodology which includes the combination of a new way for the construction of an embedding by the spatio-temporal data expansion and nonlinear model construction on the basis of artificial neural networks. The methodology is aplied to NCEP/NCAR reanalysis data including fields of sea level pressure, geopotential height, and wind speed, covering Northern Hemisphere. Its efficiency for the interannual forecast of various climate phenomena including ENSO, PDO, NAO and strong blocking event condition over the mid latitudes, is demonstrated. Also, we investigate the ability of the models to reproduce and predict the evolution of qualitative features of the dynamics, such as spectral peaks, critical transitions and statistics of extremes. This research was supported by the Government of the Russian Federation (Agreement No. 14.Z50.31.0033 with the Institute of Applied Physics RAS) [1] Y. I. Molkov, E. M. Loskutov, D. N. Mukhin, and A. M. Feigin, "Random

  3. Effects of interannual climate variation on phenology and growth of two alpine forbs

    SciTech Connect

    Walker, M.D.; Ingersoll, R.C.; Webber, P.J.

    1995-06-01

    Variations in growth, flowering, and phenology of two forbs, Acomastylis rossii and Bistorta bistortoides, were compared among six years (1983-1988) and five plant communities (fellfield, dry meadow, moist meadow, wet meadow, snowbed) at an alpine site in the Front Range of Colorado. The purpose was to determine the extent to which the phenological patterns of these species varied among plant communities and how interannual climate variability affects phenology and growth. There were significant differences in growth among communities for both species. In B. bistortoides, there were also significant differences among years, due primarily to the influence of a single year (1983) when leaf length increased by {approximately}10% and the average number of B. bistortoides leaves nearly doubled. Key phenological events of both species (initiation of growth, date of maximum leaf length, leaf number, and flower number) were related to snowmelt patterns, resulting in differences among communities. There were also significant differences among years, again primarily related to the single year 1983, the year of a major El Nino Southern Oscillation (ENSO) event that produced high snowfall amounts at the site. The increased leaf length in a high snow year is counterintuitive to the commonly accepted notion that alpine species may be limited by season length. We hypothesize that changes in phenology related to changes in snowfall or snowmelt will cause detectable changes in growth, but that these will not be predicted simply from phenology alone. Rather, the timing of snowmelt in relation to nutrient availability, soil moisture, and air temperature will be critical in determining how individual species respond. 90 refs., 7 figs., 3 tabs.

  4. Identifying the Holocene evolution of interannual climate variability in Southern California river runoff records.

    NASA Astrophysics Data System (ADS)

    Hendy, I. L.; Hinnov, L.; Brown, E. T.; Napier, T.

    2015-12-01

    Precipitation patterns in southern California are strongly correlated with El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) climate variability during the 20th Century. Heavy rainfall in southern California is generated by warm-wet storms associated with atmospheric rivers (ARs) producing flood events, while drought conditions occur when winter precipitation associated with north Pacific low pressure systems does not reach the region. Winter rainfall delivers siliciclastic sediment to Santa Barbara Basin (SBB), CA while spring summer marine productivity provides biogenic sediment resulting in a simple two component laminae couplet. Laminations are preserved in the low oxygen bottom of SBB providing a high temporal resolution paleoclimate record. Here we present scanning XRF generated annually resolved elemental concentrations for the last 9.5 ka in SBB from SPR0901-03KC (34°16.99'N; 120°2.408'W) and MV0811-14JPC (34°16.54'N; 120°2.10'W) in ~586 m water depth. High siliciclastic elemental counts are interpreted as indicating increased river runoff, while low values indicate droughts. Floods events indicative of extreme precipitation events occur throughout the Holocene, however long intervals between floods occur 8.5-7 Ka, 5.6-6.4 Ka and 0.8-1.1 Ka. Notable droughts occur 5.6-6.1, 4.7-5.1, 3.5-4.1, 2.6, 2.1, 1.8, 1.1 and 0.9 Ka. Spectral analysis indicates silicilastic elemental peaks are close to an annual resolution, however annual tuning increases the power of the interannual frequencies without changing the frequency appreciably. High frequency variability is lost during drought intervals.

  5. Ground-Water Availability Responses to Climate Variability on Interannual to Multidecadal Timescales, Mississippi Embayment Regional Aquifer System, USA

    NASA Astrophysics Data System (ADS)

    Gurdak, J. J.; Clark, B. R.; Hanson, R. T.; Scheiderer, R. M.

    2008-12-01

    Climate variability on interannual to multidecadal timescales has important implications for the availability of global ground-water resources. Spatiotemporal patterns in precipitation, air temperature, evapotranspiration, drought, streamflow, and recharge are partially controlled by the variability in climate forcings on interannual to multidecadal timescales. Because these climate-varying conditions can augment or diminish human stresses (pumping) on ground water, the responses in water levels and ground-water storage can be dramatic when different climate cycles lie coincident in a positive (wet/cool) or negative (dry/warm) phase of variability. Thus, understanding climate cycles on these timescales has particular relevance for management decisions during drought and for ground-water resources close to the limits of sustainability. The objective of this study is to quantify the response of ground-water resources in the Mississippi Embayment Regional aquifer system (USA) (>181,000 km2) to natural climate variability on interannual to multidecadal timescales and to use that knowledge to improve calibration of ground-water availability modeling that will predict the responses in this regional aquifer system over the next twenty-five to fifty years. The Mississippi Embayment Regional aquifer system is an important water resource used predominantly for public-drinking and agricultural supply across parts of seven States (Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Missouri, and Tennessee). Using singular spectrum analysis of long-term hydrologic time series, the signal of ground-water pumping was removed and natural variations were identified in all tree ring, precipitation, air temperature, and ground-water level time series as partially coincident with known climate forcings; including the El Nino/Southern Oscillation (2 to 6 year cycle), the Pacific Decadal Oscillation (10 to 25 year cycle), and the Atlantic Multidecadal Oscillation (50 to 80 year cycle

  6. Interannual climate variations in Arctic as driven by the Global atmosphere oscillation

    NASA Astrophysics Data System (ADS)

    Serykh, Ilya; Byshev, Vladimir; Neiman, Victor; Sidorova, Alexandra; Sonechkin, Dmitry

    2015-04-01

    The present-day global climate change affects the Arctic basin substantially more because of the sea ice cover extinction and the permafrost melting. But there are essential variations of these effects from year to year. We believe that these variations might be a regional manifestation of a planetary-scale phenomenon named the Global atmospheric oscillation (GAO). GAO includes the well-known El Niño - Southern Oscillation (ENSO) process and similar processes in equatorial Atlantic and Indian Oceans within itself. The goal of this report is to present some arguments to support this point of view. For this goal, we have studied some interrelations between the above-mentioned Arctic anomalies and GAO as seen in global re-analyses of the sea level pressure (SLP) and near surface temperature (NST) for the period of 1920-2013. The mean global fields of SLP and NST have been computed for all El Niño events falling into this time period, and separately, for all and La Niña events. As a result, two (for SLP and NST as well) global fields of the mean El Niño/La Niña difference were obtained. Statistical significance of the non-zero values of these fields, i.e. the reality of GAO, was evaluated with the t-Student's test. It turned out that the main spatial structures of GAO, presented specifically by El Niño and La Niña events in Pacific region, exist at a very high level (up to 99%, t>4) of the significance. Therefore, one can conclude that the interannual-scale dynamics of GAO is actually reflected in the climate features of different regions of the Earth, including the Russian Arctic. In particular, when the boreal winter season coincides with an El Niño event GAO is indicative by a negative anomaly of NST (about -1°C) and a positive anomaly of SLP over the Arctic basin. In contrary, significant (about +1°C) positive anomaly of NST along with reduced SLP over the whole Arctic region is typical for any La Niña event (up to 95%, t>2). To control the reliability

  7. Interannual to Decadal Variability of Ocean Evaporation as Viewed from Climate Reanalyses

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Bosilovich, Michael G.; Roberts, Jason B.; Wang, Hailan

    2015-01-01

    Questions we'll address: Given the uncoupled framework of "AMIP" (Atmosphere Model Inter-comparison Project) experiments, what can they tell us regarding evaporation variability? Do Reduced Observations Reanalyses (RedObs) using Surface Fluxes and Clouds (SFC) pressure (and wind) provide a more realistic picture of evaporation variability? What signals of interannual variability (e.g. El Nino/Southern Oscillation (ENSO)) and decadal variability (Interdecadal Pacific Oscillation (IPO)) are detectable with this hierarchy of evaporation estimates?

  8. Interannual variation of carbon fluxes from three contrasting evergreen forests: The role of forest dynamics and climate

    USGS Publications Warehouse

    Sierra, C.A.; Loescher, H.W.; Harmon, M.E.; Richardson, A.D.; Hollinger, D.Y.; Perakis, S.S.

    2009-01-01

    Interannual variation of carbon fluxes can be attributed to a number of biotic and abiotic controls that operate at different spatial and temporal scales. Type and frequency of disturbance, forest dynamics, and climate regimes are important sources of variability. Assessing the variability of carbon fluxes from these specific sources can enhance the interpretation of past and current observations. Being able to separate the variability caused by forest dynamics from that induced by climate will also give us the ability to determine if the current observed carbon fluxes are within an expected range or whether the ecosystem is undergoing unexpected change. Sources of interannual variation in ecosystem carbon fluxes from three evergreen ecosystems, a tropical, a temperate coniferous, and a boreal forest, were explored using the simulation model STANDCARB. We identified key processes that introduced variation in annual fluxes, but their relative importance differed among the ecosystems studied. In the tropical site, intrinsic forest dynamics contributed ?? 30% of the total variation in annual carbon fluxes. In the temperate and boreal sites, where many forest processes occur over longer temporal scales than those at the tropical site, climate controlled more of the variation among annual fluxes. These results suggest that climate-related variability affects the rates of carbon exchange differently among sites. Simulations in which temperature, precipitation, and radiation varied from year to year (based on historical records of climate variation) had less net carbon stores than simulations in which these variables were held constant (based on historical records of monthly average climate), a result caused by the functional relationship between temperature and respiration. This suggests that, under a more variable temperature regime, large respiratory pulses may become more frequent and high enough to cause a reduction in ecosystem carbon stores. Our results also show

  9. Interannual variation of carbon fluxes from three contrasting evergreen forests: the role of forest dynamics and climate.

    PubMed

    Sierra, Carlos A; Loescher, Henry W; Harmon, Mark E; Richardson, Andrew D; Hollinger, David Y; Perakis, Steven S

    2009-10-01

    Interannual variation of carbon fluxes can be attributed to a number of biotic and abiotic controls that operate at different spatial and temporal scales. Type and frequency of disturbance, forest dynamics, and climate regimes are important sources of variability. Assessing the variability of carbon fluxes from these specific sources can enhance the interpretation of past and current observations. Being able to separate the variability caused by forest dynamics from that induced by climate will also give us the ability to determine if the current observed carbon fluxes are within an expected range or whether the ecosystem is undergoing unexpected change. Sources of interannual variation in ecosystem carbon fluxes from three evergreen ecosystems, a tropical, a temperate coniferous, and a boreal forest, were explored using the simulation model STANDCARB. We identified key processes that introduced variation in annual fluxes, but their relative importance differed among the ecosystems studied. In the tropical site, intrinsic forest dynamics contributed approximately 30% of the total variation in annual carbon fluxes. In the temperate and boreal sites, where many forest processes occur over longer temporal scales than those at the tropical site, climate controlled more of the variation among annual fluxes. These results suggest that climate-related variability affects the rates of carbon exchange differently among sites. Simulations in which temperature, precipitation, and radiation varied from year to year (based on historical records of climate variation) had less net carbon stores than simulations in which these variables were held constant (based on historical records of monthly average climate), a result caused by the functional relationship between temperature and respiration. This suggests that, under a more variable temperature regime, large respiratory pulses may become more frequent and high enough to cause a reduction in ecosystem carbon stores. Our results

  10. Changes in interannual climate sensitivities of terrestrial carbon fluxes during the 21st century predicted by CMIP5 Earth System Models

    NASA Astrophysics Data System (ADS)

    Liu, Yongwen; Wang, Tao; Huang, Mengtian; Yao, Yitong; Ciais, Philippe; Piao, Shilong

    2016-03-01

    Terrestrial carbon fluxes are sensitive to climate change, but the interannual climate sensitivity of the land carbon cycle can also change with time. We analyzed the changes in responses of net biome production (NBP), net primary production (NPP), and heterotrophic respiration (Rh) to interannual climate variations over the 21st century in the Earth System Models (ESMs) from the Coupled Model Intercomparison Project 5. Under Representative Concentration Pathway (RCP) 4.5, interannual temperature sensitivities of NBP (γTempNBP), NPP (γTempNPP), and Rh (γTempRh) remain relatively stable at global scale, yet with large differences among ESMs and spatial heterogeneity. Modeled γTempNPP and γTempRh appear to increase in parallel in boreal regions, resulting in unchanged γTempNBP. Tropical γTempNBP decreases in most models, due to decreasing γTempNPP and relatively stable γTempRh. Across models, the changes in γTempNBP can be mainly explained by changes in γTempNPP rather than changes in γTempRh, at both global and regional scales. Interannual precipitation sensitivities of global NBP (γPrecNBP), NPP (γPrecNPP), and Rh (γPrecRh) are predicted not to change significantly, with large differences among ESMs. Across models, the changes in γPrecNBP can be mainly explained by changes in γPrecNPP rather than changes in γPrecRh in temperate regions, but not in other regions. Changes in the interannual climate sensitivities of carbon fluxes are consistent across RCPs 4.5, 6.0, and 8.5 but larger in more intensive scenarios. More effort should be considered to improve terrestrial carbon flux responses to interannual climate variability, e.g., incorporating biogeochemical processes of nutrient limitation, permafrost dynamics, and microbial decomposition.

  11. Feedback of observed interannual vegetation change: a regional climate model analysis for the West African monsoon

    NASA Astrophysics Data System (ADS)

    Klein, Cornelia; Bliefernicht, Jan; Heinzeller, Dominikus; Gessner, Ursula; Klein, Igor; Kunstmann, Harald

    2016-06-01

    West Africa is a hot spot region for land-atmosphere coupling where atmospheric conditions and convective rainfall can strongly depend on surface characteristics. To investigate the effect of natural interannual vegetation changes on the West African monsoon precipitation, we implement satellite-derived dynamical datasets for vegetation fraction (VF), albedo and leaf area index into the Weather Research and Forecasting model. Two sets of 4-member ensembles with dynamic and static land surface description are used to extract vegetation-related changes in the interannual difference between August-September 2009 and 2010. The observed vegetation patterns retain a significant long-term memory of preceding rainfall patterns of at least 2 months. The interannual vegetation changes exhibit the strongest effect on latent heat fluxes and associated surface temperatures. We find a decrease (increase) of rainy hours over regions with higher (lower) VF during the day and the opposite during the night. The probability that maximum precipitation is shifted to nighttime (daytime) over higher (lower) VF is 12 % higher than by chance. We attribute this behaviour to horizontal circulations driven by differential heating. Over more vegetated regions, the divergence of moist air together with lower sensible heat fluxes hinders the initiation of deep convection during the day. During the night, mature convective systems cause an increase in the number of rainy hours over these regions. We identify this feedback in both water- and energy-limited regions of West Africa. The inclusion of observed dynamical surface information improved the spatial distribution of modelled rainfall in the Sahel with respect to observations, illustrating the potential of satellite data as a boundary constraint for atmospheric models.

  12. Drivers of interannual variability in virioplankton abundance at the coastal western Antarctic peninsula and the potential effects of climate change.

    PubMed

    Evans, Claire; Brandsma, Joost; Pond, David W; Venables, Hugh J; Meredith, Michael P; Witte, Harry J; Stammerjohn, Sharon; Wilson, William H; Clarke, Andrew; Brussaard, Corina P D

    2017-02-01

    An 8-year time-series in the Western Antarctic Peninsula (WAP) with an approximately weekly sampling frequency was used to elucidate changes in virioplankton abundance and their drivers in this climatically sensitive region. Virioplankton abundances at the coastal WAP show a pronounced seasonal cycle with interannual variability in the timing and magnitude of the summer maxima. Bacterioplankton abundance is the most influential driving factor of the virioplankton, and exhibit closely coupled dynamics. Sea ice cover and duration predetermine levels of phytoplankton stock and thus, influence virioplankton by dictating the substrates available to the bacterioplankton. However, variations in the composition of the phytoplankton community and particularly the prominence of Diatoms inferred from silicate drawdown, drive interannual differences in the magnitude of the virioplankton bloom; likely again mediated through changes in the bacterioplankton. Their findings suggest that future warming within the WAP will cause changes in sea ice that will influence viruses and their microbial hosts through changes in the timing, magnitude and composition of the phytoplankton bloom. Thus, the flow of matter and energy through the viral shunt may be decreased with consequences for the Antarctic food web and element cycling.

  13. Effects of climatic factors and ecosystem responses on the inter-annual variability of evapotranspiration in a coniferous plantation in subtropical China.

    PubMed

    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.

  14. 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

  15. Interannual variations in spring phenology and their response to climate change across the Tibetan Plateau from 1982 to 2013.

    PubMed

    Liu, Lingling; Zhang, Xiaoyang; Donnelly, Alison; Liu, Xinjie

    2016-10-01

    Land surface phenology has been widely used to evaluate the effects of climate change on terrestrial ecosystems in recent decades. Climate warming on the Tibetan Plateau (1960-2010, 0.2 °C/decade) has been found to be greater than the global average (1951-2012, 0.12 °C/decade), which has had a significant impact on the timing of spring greenup. However, the magnitude and direction of change in spring phenology and its response to warming temperature and precipitation are currently under scientific debate. In an attempt to explore this issue further, we detected the onset of greenup based on the time series of daily two-band enhanced vegetation index (EVI2) from the advanced very high resolution radiometer (AVHRR) long-term data record (LTDR; 1982-1999) and Moderate Resolution Imaging Spectroradiometer (MODIS) Climate Modeling Grid (CMG; 2000-2013) using hybrid piecewise logistic models. Further, we examined the temporal trend in greenup onset in both individual pixels and ecoregions across the entire Tibetan Plateau over the following periods: 1982-1999, 2000-2013, and 1982-2013. The interannual variation in greenup onset was linked to the mean temperature and cumulative precipitation in the preceding month, and total precipitation during winter and spring, respectively. Finally, we investigated the relationship between interannual variation in greenup onset dates and temperature and precipitation from 1982 to 2013 at different elevational zones for different ecoregions. The results revealed no significant trend in the onset of greenup from 1982 to 2013 in more than 86 % of the Tibetan Plateau. For each study period, statistically significant earlier greenup trends were observed mainly in the eastern meadow regions while later greenup trends mainly occurred in the southwestern steppe and meadow regions both with areal coverage of less than 8 %. Although spring phenology was negatively correlated with spring temperature and precipitation in the majority of

  16. Interannual variations in spring phenology and their response to climate change across the Tibetan Plateau from 1982 to 2013

    NASA Astrophysics Data System (ADS)

    Liu, Lingling; Zhang, Xiaoyang; Donnelly, Alison; Liu, Xinjie

    2016-10-01

    Land surface phenology has been widely used to evaluate the effects of climate change on terrestrial ecosystems in recent decades. Climate warming on the Tibetan Plateau (1960-2010, 0.2 °C/decade) has been found to be greater than the global average (1951-2012, 0.12 °C/decade), which has had a significant impact on the timing of spring greenup. However, the magnitude and direction of change in spring phenology and its response to warming temperature and precipitation are currently under scientific debate. In an attempt to explore this issue further, we detected the onset of greenup based on the time series of daily two-band enhanced vegetation index (EVI2) from the advanced very high resolution radiometer (AVHRR) long-term data record (LTDR; 1982-1999) and Moderate Resolution Imaging Spectroradiometer (MODIS) Climate Modeling Grid (CMG; 2000-2013) using hybrid piecewise logistic models. Further, we examined the temporal trend in greenup onset in both individual pixels and ecoregions across the entire Tibetan Plateau over the following periods: 1982-1999, 2000-2013, and 1982-2013. The interannual variation in greenup onset was linked to the mean temperature and cumulative precipitation in the preceding month, and total precipitation during winter and spring, respectively. Finally, we investigated the relationship between interannual variation in greenup onset dates and temperature and precipitation from 1982 to 2013 at different elevational zones for different ecoregions. The results revealed no significant trend in the onset of greenup from 1982 to 2013 in more than 86 % of the Tibetan Plateau. For each study period, statistically significant earlier greenup trends were observed mainly in the eastern meadow regions while later greenup trends mainly occurred in the southwestern steppe and meadow regions both with areal coverage of less than 8 %. Although spring phenology was negatively correlated with spring temperature and precipitation in the majority of pixels

  17. The sensitivity of wood production to seasonal and interannual variations in climate in a lowland Amazonian rainforest.

    PubMed

    Rowland, Lucy; Malhi, Y; Silva-Espejo, J E; Farfán-Amézquita, F; Halladay, K; Doughty, C E; Meir, P; Phillips, O L

    2014-01-01

    Understanding climatic controls on tropical forest productivity is key to developing more reliable models for predicting how tropical biomes may respond to climate change. Currently there is no consensus on which factors control seasonal changes in tropical forest tree growth. This study reports the first comprehensive plot-level description of the seasonality of growth in a Peruvian tropical forest. We test whether seasonal and interannual variations in climate are correlated with changes in biomass increment, and whether such relationships differ among trees with different functional traits. We found that biomass increments, measured every 3 months on the two plots, were reduced by between 40 and 55% in the peak dry season (July-September) relative to peak wet season (January-March). The seasonal patterns of biomass accumulation are significantly (p < 0.01) associated with seasonal patterns of rainfall and soil water content; however, this may reflect a synchrony of seasonal cycles rather than direct physiological controls on tree growth rates. The strength of the growth seasonality response among trees is significantly correlated to functional traits: consistent with a hypothesised trade-off between maximum potential growth rate and hydraulic safety, tall and fast-growing trees with broad stems had the most strongly seasonal biomass accumulation, suggesting that they are more productive in the wet season, but more vulnerable to water limitation in the dry season.

  18. Interannual abundance changes of gelatinous carnivore zooplankton unveil climate-driven hydrographic variations in the Iberian Peninsula, Portugal.

    PubMed

    D'Ambrosio, Mariaelena; Molinero, Juan C; Azeiteiro, Ulisses M; Pardal, Miguel A; Primo, Ana L; Nyitrai, Daniel; Marques, Sónia C

    2016-09-01

    The persistent massive blooms of gelatinous zooplankton recorded during recent decades may be indicative of marine ecosystem changes. In this study, we investigated the potential influence of the North Atlantic climate (NAO) variability on decadal abundance changes of gelatinous carnivore zooplankton in the Mondego estuary, Portugal, over the period 2003-2013. During the 11-year study, the community of gelatinous carnivores encompassed a larger diversity of hydromedusae than siphonophores; the former dominated by Obelia spp., Lizzia blondina, Clythia hemisphaerica, Liriope tetraphylla and Solmaris corona, while the latter dominated by Muggiaea atlantica. Gelatinous carnivore zooplankton displayed marked interannual variability and mounting species richness over the period examined. Their pattern of abundance shifted towards larger abundances ca. 2007 and significant phenological changes. The latter included a shift in the mean annual pattern (from unimodal to bimodal peak, prior and after 2007 respectively) and an earlier timing of the first annual peak concurrent with enhanced temperatures. These changes were concurrent with the climate-driven environmental variability mainly controlled by the NAO, which displayed larger variance after 2007 along with an enhanced upwelling activity. Structural equation modelling allowed depicting cascading effects derived from the NAO influence on regional climate and upwelling variability further shaping water temperature. Such cascading effect percolated the structure and dynamics of the community of gelatinous carnivore zooplankton in the Mondego estuary.

  19. Linking diurnal cycles of river flow to interannual variations in climate

    USGS Publications Warehouse

    Lundquist, Jessica D.; Dettinger, Michael D.

    2003-01-01

    Many rivers in the Western United States have diurnal variations exceeding 10% of their mean flow in the spring and summer months. The shape and timing of the diurnal cycle is influenced by an interplay of the snow, topography, vegetation, and meteorology in a basin, and the measured result differs between wet and dry years. The largest interannual differences occur during the latter half of the melt season, as the snowline retreats to the highest elevations and most shaded slopes in a basin. In most basins, during this period, the hour of peak discharge shifts to later in the day, and the relative amplitude of the diurnal cycle decreases. The magnitude and rate of these changes in the diurnal cycle vary between years and may provide clues about how long- term hydroclimatic variations affect short-term basin dynamics.

  20. Spectral Kernel Approach to Study Radiative Response of Climate Variables and Interannual Variability of Reflected Solar Spectrum

    NASA Technical Reports Server (NTRS)

    Jin, Zhonghai; Wielicki, Bruce A.; Loukachine, Constantin; Charlock, Thomas P.; Young, David; Noeel, Stefan

    2011-01-01

    The radiative kernel approach provides a simple way to separate the radiative response to different climate parameters and to decompose the feedback into radiative and climate response components. Using CERES/MODIS/Geostationary data, we calculated and analyzed the solar spectral reflectance kernels for various climate parameters on zonal, regional, and global spatial scales. The kernel linearity is tested. Errors in the kernel due to nonlinearity can vary strongly depending on climate parameter, wavelength, surface, and solar elevation; they are large in some absorption bands for some parameters but are negligible in most conditions. The spectral kernels are used to calculate the radiative responses to different climate parameter changes in different latitudes. The results show that the radiative response in high latitudes is sensitive to the coverage of snow and sea ice. The radiative response in low latitudes is contributed mainly by cloud property changes, especially cloud fraction and optical depth. The large cloud height effect is confined to absorption bands, while the cloud particle size effect is found mainly in the near infrared. The kernel approach, which is based on calculations using CERES retrievals, is then tested by direct comparison with spectral measurements from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) (a different instrument on a different spacecraft). The monthly mean interannual variability of spectral reflectance based on the kernel technique is consistent with satellite observations over the ocean, but not over land, where both model and data have large uncertainty. RMS errors in kernel ]derived monthly global mean reflectance over the ocean compared to observations are about 0.001, and the sampling error is likely a major component.

  1. Climate co-variability between South America and Southern Africa at interannual, intraseasonal and synoptic scales

    NASA Astrophysics Data System (ADS)

    Puaud, Yohan; Pohl, Benjamin; Fauchereau, Nicolas; Macron, Clémence; Beltrando, Gérard

    2016-08-01

    This paper investigates and quantifies co-variability between large-scale convection in the South American and Southern African sectors at different timescales (interannual, intraseasonal and synoptic), during the austral summer seasons (November-February) from 1979 to 2012. Multivariate analyses (Canonical Correlation Analysis and Principal Component Analysis) are applied to daily outgoing longwave radiation (OLR, used as a proxy for atmospheric convection) anomalies to extract the principal modes of variability and co-variability in each and between both regions, filtered to consider the appropriate time-scales. At the interannual timescale, results confirm the predominant role of El Niño Southern Oscillation (ENSO), favoring enhanced convection over both southeastern Brazil and northern Argentina on the one hand, and tropical Africa and the western Indian Ocean on the other hand. At the intraseasonal timescale, the leading mode of co-variability is related to modulations of large-scale atmospheric convection over most of South America, and 10 days later, tropical Southern Africa. This mode accounts for the impacts of the Madden-Julian-oscillation (MJO) over these regions: identifying robust co-variability at the intraseasonal timescale between both regions require thus to consider a temporal shift between the two sectors. At the synoptic scale, however, co-variability consists mostly of a synchronous modulation of the large-scale atmospheric convection over the South American and Southern African sectors. This results from the development of concomitant Rossby waves forming a continuous wave train over the South Atlantic in the mid-latitudes, affecting both the South Atlantic and South Indian Convergence Zones. Among the days when convection shows significant anomalies (30 % of the total days in each sector), this synchronous mode occurs about 25 % of the time, individual Rossby waves modulating convection over one single region only during the remaining 75

  2. Impact of inter-annual climatic variability on ecosystem carbon exchange in two grazed temperate grasslands with contrasting drainage regimes

    NASA Astrophysics Data System (ADS)

    Choncubhair, Órlaith Ní; Humphreys, James; Lanigan, Gary

    2014-05-01

    Temperate grasslands constitute over 30% of the Earth's naturally-occurring biomes and make an important contribution towards the partial mitigation of anthropogenic greenhouse gas emissions by terrestrial ecosystems. Accumulation of carbon (C) in grassland systems predominantly takes place in below-ground repositories, enhanced by the presence of a stable soil environment with low carbon turnover rates, active rhizodeposition and high levels of residue and organic inputs. Predicted future warming is expected to increase productivity in temperate zones, thereby enhancing rates of terrestrial carbon sequestration. However, the susceptibility of many ecosystems, including grasslands, to extreme climatic events and inter-annual variability has been demonstrated previously. Temperature anomalies as well as modifications in the temporal pattern and quantity of precipitation alter the balance between carbon uptake and release processes and a mechanistic understanding of ecosystem response to such changes is still lacking. In the present study, the impact of extreme inter-annual variability in summer rainfall and temperature on carbon dynamics in two rotationally-grazed grasslands in Ireland was examined. The sites experience similar temperate climatic regimes but differ in soil drainage characteristics. Eddy covariance measurements of net ecosystem exchange of carbon were complemented by regular assessment of standing biomass, leaf cover, harvest exports and organic amendment inputs. The summers of 2012 and 2013 showed contrasting climatic conditions, with summer precipitation 93% higher and 25% lower respectively than long-term means. In addition, soil temperatures were 7% lower and 11% higher than expected. Cool, wet conditions in 2012 facilitated net carbon uptake for more than ten months of the year at the poorly-drained site, however the ecosystem switched to a net source of carbon in 2013 during months with significantly reduced rainfall. In contrast, net C

  3. Seasonal and inter-annual variability of the net ecosystem CO2 exchange of a temperate mountain grassland: effects of climate and management

    PubMed Central

    Wohlfahrt, Georg; Hammerle, Albin; Haslwanter, Alois; Bahn, Michael; Tappeiner, Ulrike; Cernusca, Alexander

    2013-01-01

    The role and relative importance of climate and cutting for the seasonal and inter-annual variability of the net ecosystem CO2 (NEE) of a temperate mountain grassland was investigated. Eddy covariance CO2 flux data and associated measurements of the green area index and the major environmental driving forces acquired during 2001-2006 at the study site Neustift (Austria) were analyzed. Driven by three cutting events per year which kept the investigated grassland in a stage of vigorous growth, the seasonal variability of NEE was primarily modulated by gross primary productivity (GPP). The role of environmental parameters in modulating the seasonal variability of NEE was obscured by the strong response of GPP to changes in the amount of green area, as well as the cutting-mediated decoupling of phenological development and the seasonal course of climate drivers. None of the climate and management metrics examined was able to explain the inter-annual variability of annual NEE. This is thought to result from (1) a high covariance between GPP and ecosystem respiration (Reco) at the annual time scale which results in a comparatively small inter-annual variation of NEE, (2) compensating effects between carbon exchange during and outside the management period, and (3) changes in the biotic response to rather than the climate variables per se. GPP was more important in modulating inter-annual variations in NEE in spring and before the first and second cut, while Reco explained a larger fraction of the inter-annual variability of NEE during the remaining, in particular the post-cut, periods. PMID:24383047

  4. Fluorscence signatures of dissolved organic material in an alpine lake ecosystem: responses to interannual climate variation and nutrient cycling

    NASA Astrophysics Data System (ADS)

    McKnight, Diane; Olivier, Matt; Hell, Katherina

    2016-04-01

    During snowmelt alpine lakes receive lower concentrations of dissolved organic material (DOM) that originates from the surrounding watershed than sub-alpine and montane lakes at lower elevations. Alpine lakes also have a shorter ice-free period that constrains the summer season of phytoplankton growth. Nonetheless, previous study of the reactive transport and production of DOM in an alpine lake in the Colorado Front Range during snowmelt and the summer ice-free season has shown that changes in DOM sources and the influence of biogeochemical processes can be resolved using fluorescence spectroscopy. Here we examine inter-annual variations in DOM fluorescence signatures during the snowmelt and summer periods in comparison to records of climate, residence time and primary production in the lake during the summer. Our analysis shows that variation in chlorophyll a concentration is a driver for variations in the fluorescence index (FI), as well as for specific ultra-violet absorbance. This result supports the predictions from the previous reactive transport modeling. We also conducted mesocosm experiments with nutrient enrichment to explore the role of nitrogen and phosphorus availability in influencing the fluorescence signature of DOM in summer. These results suggest that monitoring of simple spectroscopic properties of DOM can provide a means to track the biogeochemical consequences for alpine lakes of "too much" summer as climate continues to change.

  5. The Role of Lightning in Controlling Interannual Variability of Tropical Tropospheric Ozone and OH and its Implications for Climate

    NASA Technical Reports Server (NTRS)

    Murray, Lee T.; Jacob, Daniel J.; Logan, Jennifer A.; Hudman, Rynda C.; Koshak, William J.

    2012-01-01

    Nitrogen oxides (NO(x) = NO + NO2) produced by lightning make a major contribution to the production of the dominant tropospheric oxidants (OH and ozone). These oxidants control the lifetime of many trace gases including long-lived greenhouse gases, and control the source-receptor relationship of inter-hemispheric pollutant transport. Lightning is affected by meteorological variability, and therefore represents a potentially important tropospheric chemistry-climate feedback. Understanding how interannual variability (IAV) in lightning affects IAV in ozone and OH in the recent past is important if we are to predict how oxidant levels may change in a future warmer climate. However, lightning parameterizations for chemical transport models (CTMs) show low skill in reproducing even climatological distributions of flash rates from the Lightning Imaging Sensor (LIS) and the Optical Transient Detector (OTD) satellite instruments. We present an optimized regional scaling algorithm for CTMs that enables sufficient sampling of spatiotemporally sparse satellite lightning data from LIS to constrain the spatial, seasonal, and interannual variability of tropical lightning. We construct a monthly time series of lightning flash rates for 1998-2010 and 35degS-35degN, and find a correlation of IAV in total tropical lightning with El Nino. We use the IAV-constraint to drive a 9-year hindcast (1998-2006) of the GEOS-Chem 3D chemical transport model, and find the increased IAV in LNO(x) drives increased IAV in ozone and OH, improving the model fs ability to simulate both. Although lightning contributes more than any other emission source to IAV in ozone, we find ozone more sensitive to meteorology, particularly convective transport. However, we find IAV in OH to be highly sensitive to lightning NO(x), and the constraint improves the ability of the model to capture the temporal behavior of OH anomalies inferred from observations of methyl chloroform and other gases. The sensitivity of

  6. Climatic Effects on the Inter-Annual Variability of Carbon Fluxes for North America and Europe

    NASA Astrophysics Data System (ADS)

    Tomelleri, E.; Carvalhais, N.; Migliavacca, M.; Reichstein, M.; Fluxnet Lathuille Synthesis Team (Cf. Www. Fluxdata. Org)

    2010-12-01

    The connection between climate variability and global carbon cycle has already been shown to be linked with the North Atlantic Oscillation (NAO) (1). A positive phase of the NAO is associated with more and stronger winter storms crossing the North Atlantic on a more northerly route, causing major anomalies in sea surface temperature, currents and convective activity throughout the North Atlantic. A long-term trend towards very positive values has culminated in the early 1990s, and since then a decreasing trend is happening (1). Identification of the climatic drivers of the net ecosystem fluxes is becoming a rising issue. In particular the effects of year-to-year climate variability on regional budgets and the understanding of the underlying biogeochemical processes are of fundamental importance due to the intensification of extreme climatic events like precipitation (2) and drought events (3). We identified the relations between climatic variability (i.e. NAO) and the regional carbon budgets of North America and Europe over the period from 1989 to 2008. In doing this we kept special focus both on temporal and spatial scale. For this purpose we took advantage of the high-density of FLUXNET measurement sites in these areas. We applied a radiation use efficiency model for gross primary production (4) combined with a semi-empirical total ecosystem respiration model (5). As drivers for the model we used climatic and fraction of absorbed photosynthetically active radiation (FPAR) records. We utilized in-situ calibrated model parameters to estimate the regional ecosystem carbon fluxes. The model was spatially applied according to the similarity in the climatic-phenological space of each grid pixel with the measurement site to which it was calibrated (e.g., 6). We found that for Europe NAO could explain NEE variability in a reasonable way for northern and southern Europe, but for the mid-latitude region this was not the case. For North America the patterns were less clear

  7. Climate Variability and Oceanographic Settings Associated with Interannual Variability in the Initiation of Dinophysis acuminata Blooms

    PubMed Central

    Díaz, Patricio A.; Reguera, Beatriz; Ruiz-Villarreal, Manuel; Pazos, Yolanda; Velo-Suárez, Lourdes; Berger, Henrick; Sourisseau, Marc

    2013-01-01

    In 2012, there were exceptional blooms of D. acuminata in early spring in what appeared to be a mesoscale event affecting Western Iberia and the Bay of Biscay. The objective of this work was to identify common climatic patterns to explain the observed anomalies in two important aquaculture sites, the Galician Rías Baixas (NW Spain) and Arcachon Bay (SW France). Here, we examine climate variability through physical-biological couplings, Sea Surface Temperature (SST) anomalies and time of initiation of the upwelling season and its intensity over several decades. In 2012, the mesoscale features common to the two sites were positive anomalies in SST and unusual wind patterns. These led to an atypical predominance of upwelling in winter in the Galician Rías, and increased haline stratification associated with a southward advection of the Gironde plume in Arcachon Bay. Both scenarios promoted an early phytoplankton growth season and increased stability that enhanced D. acuminata growth. Therefore, a common climate anomaly caused exceptional blooms of D. acuminata in two distant regions through different triggering mechanisms. These results increase our capability to predict intense diarrhetic shellfish poisoning outbreaks in the early spring from observations in the preceding winter. PMID:23959151

  8. Effects of interannual climate variation on aboveground phytomass in alpine vegetation

    SciTech Connect

    Walker, M.D.; Webber, P.J.; Arnold, E.H. ); Ebert-May, D. )

    1994-03-01

    Relationships between peak annual vascular aboveground phytomass and annual climate variation in alpine plant communities located on Niwot Ridge, Colorado, were analyzed using path analysis. The five community types, fellfield, dry meadow, moist meadow, wet meadow, and snowbed, represent a snow depth-soil moisture gradient and broadly represent the most common vegetation types on east-facing slopes of the Front Range alpine zone. using nine successive years of data, this is the first longer term analysis of alpine phytomass and climate and one of the longest nonagricultural production records available. Live phytomass ranged from 97 g/m[sup 2] (snowbed) to 237 g/m[sup 2] (fellfield). Among-community differences in phytomass were greater than differences among years, but there was a significant phytomass variation among years. Path analysis indicated that climate accounted for 15-40% of the variation in phytomass. The dry communities, fellfield (exposed rocky summit areas dominated by cushion and mat plants) and dry meadow, were most sensitive to previous year precipitation, the moist and wet meadow communities were most sensitive to current growing season soil moisture, and the snowbed community was most sensitive to date of snow release. Because of the relatively high amount of variation attributable to variables related to precipitation, changes in precipitation regimes that may occur in alpine ecosystems will likely result in changes in phytomass that are detectable with clip-harvest methods. 62 refs., 2 figs., 6 tabs.

  9. Evaluating Antarctic sea ice predictability at seasonal to interannual timescales in global climate models

    NASA Astrophysics Data System (ADS)

    Marchi, Sylvain; Fichefet, Thierry; Goosse, Hugues; Zunz, Violette; Tietsche, Steffen; Day, Jonny; Hawkins, Ed

    2016-04-01

    Unlike the rapid sea ice losses reported in the Arctic, satellite observations show an overall increase in Antarctic sea ice extent over recent decades. Although many processes have already been suggested to explain this positive trend, it remains the subject of current investigations. Understanding the evolution of the Antarctic sea ice turns out to be more complicated than for the Arctic for two reasons: the lack of observations and the well-known biases of climate models in the Southern Ocean. Irrespective of those issues, another one is to determine whether the positive trend in sea ice extent would have been predictable if adequate observations and models were available some decades ago. This study of Antarctic sea ice predictability is carried out using 6 global climate models (HadGEM1.2, MPI-ESM-LR, GFDL CM3, EC-Earth V2, MIROC 5.2 and ECHAM 6-FESOM) which are all part of the APPOSITE project. These models are used to perform hindcast simulations in a perfect model approach. The predictive skill is estimated thanks to the PPP (Potential Prognostic Predictability) and the ACC (Anomaly Correlation Coefficient). The former is a measure of the uncertainty of the ensemble while the latter assesses the accuracy of the prediction. These two indicators are applied to different variables related to sea ice, in particular the total sea ice extent and the ice edge location. This first model intercomparison study about sea ice predictability in the Southern Ocean aims at giving a general overview of Antarctic sea ice predictability in current global climate models.

  10. Remote sensing of interannual boreal forest NDVI in relation to climatic conditions in interior Alaska

    NASA Astrophysics Data System (ADS)

    Verbyla, David

    2015-12-01

    Climate has warmed substantially in interior Alaska and several remote sensing studies have documented a decadal-scale decline in the normalized difference vegetation index (NDVI) termed a ‘browning trend’. Reduced summer soil moisture due to changing climatic factors such as earlier springs, less snowpack, and summer drought may reduce boreal productivity and NDVI. However, the relative importance of these climatic factors is poorly understood in boreal interior Alaska. In this study, I used the remotely sensed peak summer NDVI as an index of boreal productivity at 250 m pixel size from 2000 to 2014. Maximum summer NDVI was related to last day of spring snow, early spring snow water equivalent (SWE), and a summer moisture index. There was no significant correlation between early spring SWE and peak summer NDVI. There was a significant correlation between the last day of spring snow and peak summer NDVI, but only for a few higher elevation stations. This was likely due to snowmelt occurring later at higher elevations, thus having a greater effect on summer soil moisture relative to lower elevation sites. For most of boreal interior Alaska, summer drought was likely the dominant control on peak summer NDVI and this effect may persist for several years. Peak summer NDVI declined at all 26 stations after the 2004 drought, and the decline persisted for 2 years at all stations. Due to the shallow rooting zone of most boreal plants, even cool and moist sites at lower elevations are likely vulnerable to drought. For example the peak summer NDVI response following the 2004 drought was similar for adjacent cold and warm watershed basins. Thus, if frequent and severe summer droughts continue, moisture stress effects are likely to be widespread and prolonged throughout most of interior boreal Alaska, including relatively cool, moist sites regardless of spring snowpack conditions or spring phenology.

  11. Sensitivity of global tropical climate to land surface processes: Mean state and interannual variability

    SciTech Connect

    Ma, Hsi-Yen; Xiao, Heng; Mechoso, C. R.; Xue, Yongkang

    2013-03-01

    This study examines the sensitivity of global tropical climate to land surface processes (LSP) using an atmospheric general circulation model both uncoupled (with prescribed SSTs) and coupled to an oceanic general circulation model. The emphasis is on the interactive soil moisture and vegetation biophysical processes, which have first order influence on the surface energy and water budgets. The sensitivity to those processes is represented by the differences between model simulations, in which two land surface schemes are considered: 1) a simple land scheme that specifies surface albedo and soil moisture availability, and 2) the Simplified Simple Biosphere Model (SSiB), which allows for consideration of interactive soil moisture and vegetation biophysical process. Observational datasets are also employed to assess the reality of model-revealed sensitivity. The mean state sensitivity to different LSP is stronger in the coupled mode, especially in the tropical Pacific. Furthermore, seasonal cycle of SSTs in the equatorial Pacific, as well as ENSO frequency, amplitude, and locking to the seasonal cycle of SSTs are significantly modified and more realistic with SSiB. This outstanding sensitivity of the atmosphere-ocean system develops through changes in the intensity of equatorial Pacific trades modified by convection over land. Our results further demonstrate that the direct impact of land-atmosphere interactions on the tropical climate is modified by feedbacks associated with perturbed oceanic conditions ("indirect effect" of LSP). The magnitude of such indirect effect is strong enough to suggest that comprehensive studies on the importance of LSP on the global climate have to be made in a system that allows for atmosphere-ocean interactions.

  12. Interannual and long-term climate variability over the Zaire River Basin during the last 30 years

    NASA Astrophysics Data System (ADS)

    Kazadi, Sanga-Ngoie; Kaoru, Fukuyama

    1996-09-01

    Climatological data records of temperature, rainfall, and number of rainy days provided by the Zaire Meteorological Agency (METTELSAT) at seven Zairian stations for the 1960-1992 period are analyzed for the first time since the 1970s. Our investigations focus on climate variability as related with environmental changes over the Zaire River Basin, which is climatologically and biogenetically one of the most important regions in the world. On the basis of the 30-year monthly mean climatologies, it is shown that the solar annual cycle dominates the seasonal changes of both the temperature and rainfall over this region. On the interannual time-scales, the variability of these climatic variables is characterized by (1) a 2-to 5-year oscillation strongly correlated to the southern oscillation index, thus to the ENSO phenomenon, and (2) a nearly 10-year oscillation (called here the quasi-decadal oscillation, QDO) with a very remarkable correlationship with the solar activity (sunspots number). On the long-term timescale, a remarkable decreasing trend in rainfall and number of rainy days, as well as increasing temperatures over the 30-year period, has been detected as the most dominant climatological features all over the basin. The magnitudes of temperature increase are by far larger than those reported in previous works for both the global mean and hemispherical mean warmings. We postulate that this trend of regional warming and desiccation from within the heart of the African rainforests is due to the increase in surface albedo, itself triggered by uncontrolled land-use policies and forests development over this area (logging, slash and burn, bushfire, fuelwood, farming, ranching, urbanization, etc.).

  13. Climate and socioeconomic influences on interannual variability of cholera in Nigeria.

    PubMed

    Leckebusch, Gregor C; Abdussalam, Auwal F

    2015-07-01

    Cholera is one of the most important climate sensitive diseases in Nigeria that pose a threat to public health because of its fatality and endemic nature. This study aims to investigate the influences of meteorological and socioeconomic factors on the spatiotemporal variability of cholera morbidity and mortality in Nigeria. Stepwise multiple regression and generalised additive models were fitted for individual states as well as for three groups of the states based on annual precipitation. Different meteorological variables were analysed, taking into account socioeconomic factors that are potentially enhancing vulnerability (e.g. absolute poverty, adult literacy, access to pipe borne water). Results quantify the influence of both climate and socioeconomic variables in explaining the spatial and temporal variability of the disease incidence and mortality. Regional importance of different factors is revealed, which will allow further insight into the disease dynamics. Additionally, cross validated models suggest a strong possibility of disease prediction, which will help authorities to put effective control measures in place which depend on prevention, and or efficient response.

  14. Seasonal and Interannual Trends in Largest Cholera Endemic Megacity: Water Sustainability - Climate - Health Challenges in Dhaka, Bangladesh

    NASA Astrophysics Data System (ADS)

    Akanda, Ali S.; Jutla, Antarpreet; Faruque, Abu S. G.; Huq, Anwar; Colwell, Rita R.

    2014-05-01

    The last three decades of surveillance data shows a drastic increase of cholera prevalence in the largest cholera-endemic city in the world - Dhaka, Bangladesh. Emerging megacities in the region, especially those located in coastal areas also remain vulnerable to large scale drivers of cholera outbreaks. However, there has not been any systematic study on linking long-term disease trends with related changes in natural or societal variables. Here, we analyze the 30-year dynamics of urban cholera prevalence in Dhaka with changes in climatic or anthropogenic forcings: regional hydrology, flooding, water usage, changes in distribution systems, population growth and density in urban settlements, as well as shifting climate patterns and frequency of natural disasters. An interesting change is observed in the seasonal trends of cholera prevalence; while an endemic upward trend is seen in the dry season, the post-monsoon trend is epidemic in nature. In addition, the trend in the pre-monsoon dry season is significantly stronger than the post-monsoon wet season; and thus spring is becoming the dominant cholera season of the year. Evidence points to growing urbanization and rising population in unplanned settlements along the city peripheries. The rapid pressure of growth has led to an unsustainable and potentially disastrous situation with negligible-to-poor water and sanitation systems compounded by changing climatic patterns and increasing number of extreme weather events. Growing water scarcity in the dry season and lack of sustainable water and sanitation infrastructure for urban settlements have increased endemicity of cholera outbreaks in spring, while record flood events and prolonged post-monsoon inundation have contributed to increased epidemic outbreaks in fall. We analyze our findings with the World Health Organization recommended guidelines and investigate large scale water sustainability challenges in the context of climatic and anthropogenic changes in the

  15. Coral records of interannual, century and millenium scale climate dynamics in the tropical eastern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Abram, N. J.; Gagan, M. K.; Chappell, J.; McCulloch, M. T.; Hantoro, W. S.

    2003-04-01

    Climate in the tropical eastern Indian Ocean is dominated by the Asian monsoon but is also strongly influenced by the El Niño-Southern Oscillation (ENSO) and is the core area of activity for the Indian Ocean Dipole. We examined the interaction of these climate systems over the past 7000 years using the δ18O and Sr/Ca records of 5 modern and 33 fossil corals from the Mentawai Islands, southwest Sumatra, Indonesia. The mean δ18O and Sr/Ca values of the fossil corals define a maxima in sea surface temperature (SST) and salinity at 6.5 ka, which was followed by cooling and freshening to 4.5 ka. On the seasonal scale this cooling/freshening trend is manifest as an increase in the annual SST cycle and an increase in the frequency of Indian Ocean Dipole events. This suggests a stronger southeast Monsoon causing increased Ekman upwelling along the Sumatran coast. The fossil corals record rapid warming and drying from 4.5 to 4ka. The peak of this event corresponds to the timing of a major drought recorded in African lake levels and ice cores. The period around 2ka is characterised by rapid fluctuations in mean SST but relatively stable salinity at values close to the present day warm pool conditions. This variability in SST may reflect an increase in the strength of the ENSO system after 4ka. Changes in SST and salinity recorded by the fossil corals over the past 1000 years closely match variations in solar activity, with a distinct cool and fresh period between 0.5ka and 0.4ka that corresponds with the Sp&{uml;o}rer solar minima, as well as with high lake levels in Africa. High-resolution coral records for the past 150 years allow for a detailed examination of the interactions between the Asian Monsoon, ENSO and the Indian Ocean Dipole climate systems since 1857. This record shows that large Indian Ocean Dipole events, such as observed in 1994 and 1997, have been infrequent with only two other similar-scale events recorded since 1857. More frequent and stronger Indian

  16. Effects of Interannual Climate Variability in Secondary Forests and Crops Under Traditional and Alternative Shifting Cultivation

    NASA Astrophysics Data System (ADS)

    Sa, T. D.; Guild, L. S.; Carvalho, C. J.; Potter, C. S.; Wickel, A. J.; Brienza, S.; Kato, M. A.; Kato, O.

    2002-12-01

    Regenerating forests play an important role in long-term carbon sequestration and sustainable landuse as they act as potentially important carbon and nutrient sinks during the shifting agriculture fallow period. The long-term functioning of secondary forests (capoeira) is increasingly threatened by a shortening fallow period during shifting cultivation due to demographic pressures and associated increased vulnerability to severe climatic events. Declining productivity and functioning of fallow forests of shifting cultivation combined with progressive loss of nutrients by successive burning and cropping activities has resulted in declining agricultural productivity. In addition to the effects of intense land use practices, droughts associated with El Ni¤o events are becoming more frequent and severe in moist tropical forests and negative effects on capoeira productivity could be considerable. In Igarape-Acu (near Belem, Para), we hypothesize that experimental alternative landuse/clearing practices (mulching and fallow vegetation improvement by planting with fast-growing leguminous tree species) may make capoeira and crops more resilient to the effects of agricultural pressures and drought through 1) increased biomass, soil organic matter and associated increase in soil water storage, and nutrient retention and 2) greater rooting depth of trees planted for fallow improvement. This experimental practice (mechanized chop-and-mulch with fallow improvement) has resulted in increased soil moisture during the cropping phase, reduced loss of nutrients and organic matter, and higher rates of secondary-forest biomass accumulation. We present preliminary data on water relations during the dry season of 2001 in capoeira and crops for both traditional slash-and-burn and alternative chop-and-mulch practices. These data will be used to test IKONOS data for the detection of moisture status differences. The principal goal of the research is to determine the extent to which capoeira

  17. Integrating interannual climate variability forecasts into weather-indexed crop insurance. The case of Malawi, Kenya and Tanzania

    NASA Astrophysics Data System (ADS)

    Vicarelli, M.; Giannini, A.; Osgood, D.

    2009-12-01

    possible payouts using historical precipitation data and analyzed the differences between years with different ENSO states from 1961 to 2005; (ii) we applied Monte Carlo methods to simulate precipitation distributions in each location and calculated the mean and variance of payouts associated to different ENSO states. The results obtained from historical precipitation data indicate that more abundant rainfall reduces payouts and the risk of loan default during La Niña in southern Kenya and Malawi, during El Niño in Tanzania. The results of the Monte Carlo simulations confirm our findings. Our results suggest that re-insurance schemes could be successfully designed to exploit the anti-correlation patterns related to interannual climate variability for different regions in Africa. Moreover, the exploratory framework presented can potentially be refined applied to other regions (e.g. Central and Latin America).

  18. Climate and Developmental Plasticity: Interannual Variability in Grapevine Leaf Morphology1[OPEN

    PubMed Central

    Li, Darren Y.; Woodford, Quaneisha L.; Yu, Tommy T.

    2016-01-01

    The shapes of leaves are dynamic, changing over evolutionary time between species, within a single plant producing different shaped leaves at successive nodes, during the development of a single leaf as it allometrically expands, and in response to the environment. Notably, strong correlations between the dissection and size of leaves with temperature and precipitation exist in both the paleorecord and extant populations. Yet, a morphometric model integrating evolutionary, developmental, and environmental effects on leaf shape is lacking. Here, we continue a morphometric analysis of >5,500 leaves representing 270 grapevines of multiple Vitis species between two growing seasons. Leaves are paired one-to-one and vine-to-vine accounting for developmental context, between growing seasons. Linear discriminant analysis reveals shape features that specifically define growing season, regardless of species or developmental context. The shape feature, a more pronounced distal sinus, is associated with the colder, drier growing season, consistent with patterns observed in the paleorecord. We discuss the implications of such plasticity in a long-lived woody perennial, such as grapevine (Vitis spp.), with respect to the evolution and functionality of plant morphology and changes in climate. PMID:26826220

  19. Murres, capelin and ocean climate: Inter-annual associations across a decadal shift

    USGS Publications Warehouse

    Regular, P.M.; Shuhood, F.; Power, T.; Montevecchi, W.A.; Robertson, G.J.; Ballam, D.; Piatt, J.F.; Nakashima, B.

    2009-01-01

    To ensure energy demands for reproduction are met, it is essential that marine birds breed during periods of peak food availability. We examined associations of the breeding chronology of common murres (Uria aalge) with the timing of the inshore arrival of their primary prey, capelin (Mallotus villosus) from 1980 to 2006 across a period of pervasive change in the Northwest Atlantic ecosystem. We also assessed the influence of ocean temperature and the North Atlantic Oscillation (NAO; an index of winter climate and oceanography) on these interactions. We found a lagged linear relationship between variations in murre breeding chronology and the timing of capelin arrival in the previous year. On a decadal level, we found a non-linear threshold relationship between ocean temperature and the timing of capelin arrival and murre breeding. Centennially anomalous cold water temperatures in 1991 generated a marked shift in the timing of capelin spawning inshore and murre breeding, delaying both by more than 2 weeks. By the mid-1990s, ocean temperatures returned to pre-perturbation levels, whereas the temporal breeding responses of capelin and murres were delayed for a decade or more. Oceanographic conditions (temperature, NAO) were poor predictors of the timing of capelin arrival inshore in the current year compared to the previous one. Our findings suggest that knowledge of the timing of capelin availability in the previous year provides a robust cue for the long-lived murres, allowing them to achieve temporal overlap between breeding and peak capelin availability. ?? Springer Science+Business Media B.V. 2008.

  20. 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

  1. Climate and the individual: inter-annual variation in the autumnal activity of the European badger (Meles meles).

    PubMed

    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, and 30cmTEMP (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.

  2. Use of the HadGEM2 climate-chemistry model to investigate interannual variability in methane sources

    NASA Astrophysics Data System (ADS)

    Hayman, Garry; O'Connor, Fiona; Clark, Douglas; Huntingford, Chris; Gedney, Nicola

    2013-04-01

    The global mean atmospheric concentration of methane (CH4) has more than doubled during the industrial era [1] and now constitutes ? 20% of the anthropogenic climate forcing by greenhouse gases [2]. The globally-averaged CH4 growth rate, derived from surface measurements, has fallen significantly from a high of 16 ppb yr-1 in the late 1970s/early 1980s and was close to zero between 1999 and 2006 [1]. This overall period of declining or low growth was however interspersed with years of positive growth-rate anomalies (e.g., in 1991-1992, 1998-1999 and 2002-2003). Since 2007, renewed growth has been evident [1, 3], with the largest increases observed over polar northern latitudes and the Southern Hemisphere in 2007 and in the tropics in 2008. The observed inter-annual variability in atmospheric methane concentrations and the associated changes in growth rates have variously been attributed to changes in different methane sources and sinks [1, 4]. In this paper, we report results from runs of the HadGEM2 climate-chemistry model [5] using year- and month-specific emission datasets. The HadGEM2 model includes the comprehensive atmospheric chemistry and aerosol package, the UK Chemistry Aerosol community model (UKCA, http://www.ukca.ac.uk/wiki/index.php). The Standard Tropospheric Chemistry scheme was selected for this work. This chemistry scheme simulates the Ox, HOx and NOx chemical cycles and the oxidation of CO, methane, ethane and propane. Year- and month-specific emission datasets were generated for the period from 1997 to 2009 for the emitted species in the chemistry scheme (CH4, CO, NOx, HCHO, C2H6, C3H8, CH3CHO, CH3CHOCH3). The approach adopted varied depending on the source sector: Anthropogenic: The emissions from anthropogenic sources were based on decadal-averaged emission inventories compiled by [6] for the Coupled Carbon Cycle Climate Model Intercomparison Project (C4MIP). These were then used to derive year-specific emission datasets by scaling the

  3. Evaluation of the inter-annual variability of stratospheric chemical composition in chemistry-climate models using ground-based multi species time series

    NASA Astrophysics Data System (ADS)

    Poulain, V.; Bekki, S.; Marchand, M.; Chipperfield, M. P.; Khodri, M.; Lefèvre, F.; Dhomse, S.; Bodeker, G. E.; Toumi, R.; De Maziere, M.; Pommereau, J.-P.; Pazmino, A.; Goutail, F.; Plummer, D.; Rozanov, E.; Mancini, E.; Akiyoshi, H.; Lamarque, J.-F.; Austin, J.

    2016-07-01

    The variability of stratospheric chemical composition occurs on a broad spectrum of timescales, ranging from day to decades. A large part of the variability appears to be driven by external forcings such as volcanic aerosols, solar activity, halogen loading, levels of greenhouse gases (GHG), and modes of climate variability (quasi-biennial oscillation (QBO), El Niño-Southern Oscillation (ENSO)). We estimate the contributions of different external forcings to the interannual variability of stratospheric chemical composition and evaluate how well 3-D chemistry-climate models (CCMs) can reproduce the observed response-forcing relationships. We carry out multivariate regression analyses on long time series of observed and simulated time series of several traces gases in order to estimate the contributions of individual forcings and unforced variability to their internannual variability. The observations are typically decadal time series of ground-based data from the international Network for the Detection of Atmospheric Composition Change (NDACC) and the CCM simulations are taken from the CCMVal-2 REF-B1 simulations database. The chemical species considered are column O3, HCl, NO2, and N2O. We check the consistency between observations and model simulations in terms of the forced and internal components of the total interannual variability (externally forced variability and internal variability) and identify the driving factors in the interannual variations of stratospheric chemical composition over NDACC measurement sites. Overall, there is a reasonably good agreement between regression results from models and observations regarding the externally forced interannual variability. A much larger fraction of the observed and modelled interannual variability is explained by external forcings in the tropics than in the extratropics, notably in polar regions. CCMs are able to reproduce the amplitudes of responses in chemical composition to specific external forcings

  4. 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

  5. Coupled ocean-atmosphere model system for studies of interannual-to-decadal climate variability over the North Pacific Basin and precipitation over the Southwestern United States

    SciTech Connect

    Lai, Chung-Chieng A.

    1997-10-01

    This is the final report of a one-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The ultimate objective of this research project is to make understanding and predicting regional climate easier. The long-term goals of this project are (1) to construct a coupled ocean-atmosphere model (COAM) system, (2) use it to explore the interannual-to-decadal climate variability over the North Pacific Basin, and (3) determine climate effects on the precipitation over the Southwestern United States. During this project life, three major tasks were completed: (1) Mesoscale ocean and atmospheric model; (2) global-coupled ocean and atmospheric modeling: completed the coupling of LANL POP global ocean model with NCAR CCM2+ global atmospheric model; and (3) global nested-grid ocean modeling: designed the boundary interface for the nested-grid ocean models.

  6. 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

  7. Statistical modeling of interannual shoreline change driven by North Atlantic climate variability spanning 2000-2014 in the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    Robinet, A.; Castelle, B.; Idier, D.; Le Cozannet, G.; Déqué, M.; Charles, E.

    2016-12-01

    Modeling studies addressing daily to interannual coastal evolution typically relate shoreline change with waves, currents and sediment transport through complex processes and feedbacks. For wave-dominated environments, the main driver (waves) is controlled by the regional atmospheric circulation. Here a simple weather regime-driven shoreline model is developed for a 15-year shoreline dataset (2000-2014) collected at Truc Vert beach, Bay of Biscay, SW France. In all, 16 weather regimes (four per season) are considered. The centroids and occurrences are computed using the ERA-40 and ERA-Interim reanalyses, applying k-means and EOF methods to the anomalies of the 500-hPa geopotential height over the North Atlantic Basin. The weather regime-driven shoreline model explains 70% of the observed interannual shoreline variability. The application of a proven wave-driven equilibrium shoreline model to the same period shows that both models have similar skills at the interannual scale. Relation between the weather regimes and the wave climate in the Bay of Biscay is investigated and the primary weather regimes impacting shoreline change are identified. For instance, the winter zonal regime characterized by a strengthening of the pressure gradient between the Iceland low and the Azores high is associated with high-energy wave conditions and is found to drive an increase in the shoreline erosion rate. The study demonstrates the predictability of interannual shoreline change from a limited number of weather regimes, which opens new perspectives for shoreline change modeling and encourages long-term shoreline monitoring programs.

  8. Interannual and orbital-scale climate variability in the early Miocene: Compound-specific D/H records from the Foulden Maar Diatomite, New Zealand

    NASA Astrophysics Data System (ADS)

    D'Andrea, W. J.; Fox, B.; Lee, D.

    2013-12-01

    The El Niño-Southern Oscillation (ENSO) cycle is the most important interannual climate variation on Earth and has far reaching impacts on global climate. However, the behavior of ENSO over orbital timescales and under different global climate states is poorly understood and controversial. It has been proposed that ENSO behaved much differently in the past, perhaps even transitioning toward a permanent El Niño-like state. Our understanding of the ENSO response to orbital variations and the background climate state is incomplete and there are fundamental flaws in our knowledge of this important player in Earth's climate system. Here we present a 100,000-yr long compound-specific hydrogen isotope (D/H) record along with varve thickness data that document southern New Zealand (46°S, 170°E) climate in the early Miocene; the results suggest modulation of ENSO by Earth's orbital changes at precession (~22,000 year) and semiprecession (~11,000 year) timescales. Our data come from analyses of the Foulden Maar Diatomite, an annually laminated sediment sequence from an early Miocene freshwater lake in Otago, New Zealand. The diatomite contains approximately 100,000 dark-light couplets interpreted as biogenic varves, and has exquisite preservation of leaves, flowers, insects, diatom frustules and n-alkanoic acids derived from leaf waxes and algae. D/H records from n-alkanoic acids reveal large variations corresponding to precession (~22,000 yrs) and semi-precession (~11,000 yrs) timescales that reflect large paleohydrological changes. Varve thickness records reveal spectral power that exceeds the 99% confidence limit in the 3 to 7-yr band, and indicate that ENSO was an important driver of interannual climate variability in southern New Zealand during the early Miocene. We propose that the semiprecession-paced hydrologic changes represented by our compound-specific D/H record document the modulation of ENSO by variations in Earth's orbital configuration; specifically, that

  9. Large-scale climate control on the occurrence of turbid events on interannual scales in a karstified, heavily exploited karst system in northwestern France

    NASA Astrophysics Data System (ADS)

    Massei, N.; Laignel, B.; Dupont, J. P.

    2015-12-01

    High-amplitude turbid episodes at water supplies can cause significant sanitary issues to populations. Owing to their hydrogeologic specificity, karst ground waters are particularly sensitive to such phenomena, involving either fast infiltration of turbid surface water or resuspension of intra-karstic sediments during flood events. In some regions, such as Upper Normandy (France), soil erosion and karst features in the chalk aquifer are at the origin of major turbid events which may result in interrupted water supply to the local populations. Thanks to a long daily turbidity time series corresponding to measurements at one major karst spring since the mid-80's, we could investigate the large-scale atmospheric circulation control on below- or above-average turbidity periods. The turbidity time-series actually display periods on pluriannual duration during which daily turbid events are more frequent and have higher amplitudes, which can not be seen on daily precipitation records. Comparison was made between annual precipitation amounts, chalk aquifer water table variations and turbidity throughout this approximately 25-year period, which showed interannual recharge periods associated to above-normal turbid conditions. We then studied the linkages between such variations and large-scale atmospheric circulation using a NOAA sea level pressure reanalysis product. A wavelet multiresolution analysis of all hydrological and climatic signals revealed common aperiodic oscillations on interannual scales and allowed identification of the large-scale, interannual-scale atmospheric pattern that was responsible for those above-normal turbid periods; this atmospheric pattern was not necessarily similar to that responsible to any individual short-term turbid event.

  10. Improving interannual prediction skill in a changing climate via the identi cation of compensating coupled model errors

    SciTech Connect

    Tziperman, Eli; MacMartin, Douglas

    2013-08-31

    Significant progress can be made through a truly interdisciplinary effort, combining the expertise from climate dynamics and from engineering control. We believe that this novel approach can make a unique and valuable contribution, and help the climate community deliver improved models for the potential response of the Earth's climate to increased greenhouse gas levels.

  11. Long series relationships between global interannual CO2 increment and climate: evidence for stability and change in role of the tropical and boreal-temperate zones.

    PubMed

    Adams, Jonathan M; Piovesan, Gianluca

    2005-06-01

    Interannual variability in global CO2 increment (averaged from the Mauna Loa and South Pole Stations) shows certain strong spatial relationships to both tropical and temperate temperatures. There is a fairly strong positive year-round correlation between tropical mean annual temperatures (leading by 4 months) and annual CO2 throughout the time series since 1960, agreeing with the generally held view that the tropics play a major role in determining inter-annual variability in CO2 increment, with a major CO2 pulse following a warm year in the tropics. This 'almost no lag' climatic response is very strong during winter and relatively stable in time. However, the correlation with tropical temperature appears to have weakened in the first years of the 1990s in correspondence of the Pinatubo eruption and the positive phase of the AO/NAO. A secondary concurrent temperature signal is linked to summer variations of north temperate belt. Northern summer temperatures in the region 30-60 degrees N-and especially in the land area corresponding to the central east USA-have become relatively more closely correlated with CO2 increment. This trend has become increasingly stronger in recent years, suggesting an increasing role for growing season processes in the northern midlatitudes in affecting global CO2 increment. Once non-lagged annual tropical temperature variations are accounted for, terrestrial ecosystems, especially the temperate-boreal biomes, also show a coherent large scale lagged response. This involves an inverse response to annual temperature of preceding years centered at around 2 years before. This lagged response is most likely linked to internal biogeochemical cycles, in particular N cycling. During the study period north boreal ecosystems show a strengthening of the lagged correlation with temperature in recent years, while the lagged correlation with areas of tropical ecosystems has weakened. Residuals from a multiple correlations based on these climatic

  12. Contribution of the terrestrial biosphere to interannual variations in atmospheric CO{sub 2}

    SciTech Connect

    King, A.W.; Post, W.M.; Wullschleger, S.D.

    1995-06-01

    Interannual fluctuations in atmospheric CO{sub 2} concentration may reflect interannual variations in the CO{sub 2} source/sink strength of the terrestrial biosphere. Recurrent changes in climate like those associated with El Nino events and episodic changes like those associated with the Mt. Pinatubo eruption could alter the global balance between terrestrial net primary production and heterotrophic (decomposer) respiration and thus influence net CO{sub 2} exchange with the atmosphere. A georeferenced global terrestrial biosphere model (0.5{degrees} spatial resolution and monthly temporal resolution) was used to simulate interannual variations in net CO{sub 2} exchange with the atmosphere. The model was driven with monthly temperature and precipitation data for the period 1900 to present. Interannual variations in simulated net CO{sub 2} exchange were compared with historical records of atmospheric CO{sub 2}. Consecutive years of an enhanced terrestrial sink were associated with periods of declining atmospheric CO{sub 2} concentration; consecutive years of enhanced source strength were associated with positive atmospheric CO{sub 2} anomalies. We conclude that interannual variations in terrestrial biospheric carbon flux contribute significantly to interannual variations in atmospheric CO{sub 2}.

  13. The role of remote versus local climatic influences in shaping seasonal to interannual rainfall isotopic variations in northern Borneo

    NASA Astrophysics Data System (ADS)

    Moerman, J. W.; Cobb, K. M.; Konecky, B. L.; Noone, D. C.

    2014-12-01

    While interannual and intraseasonal variability are the dominant influences on modern rainfall water isotopes (δ18O and δD) in northern Borneo (Moerman et al., 2013), the strong resemblance between stalagmite δ18O and equatorial boreal fall insolation over the Holocene and late Pleistocene suggests that seasonal δ18O variability is an important control on Borneo stalagmite δ18O over glacial/interglacial timescales (Carolin et al., 2013). A weak, bimodal seasonal cycle of 2-3‰ exists in northern Borneo rainfall δ18O, with relative minima during winter/summer and relative maxima during spring/fall. The seasonal cycle in rainfall δ18O, however, is poorly correlated to seasonal variations in precipitation amount. As a result, the processes driving rainfall δ18O seasonality at Borneo remain unclear. To better constrain the controlling mechanisms, we compare a 7-yr-long timeseries of daily Borneo rainfall δ18O to overlapping satellite-based measurements of GOSAT and TES tropospheric water vapor δD. To investigate the role of moist processes such as evaporation, condensation, and convection, we explore the relationship between seasonal composites of water vapor δD and specific humidity in the Borneo region. We also use HYSPLIT air mass back-trajectories to differentiate local (e.g. moisture recycling, local convection/evaporation) versus regional (e.g. moisture source region, trajectory, and convective activity) controls on the seasonal isotopic composition of Borneo rainfall. Given the sensitivity of Borneo rainfall δ18O to interannual shifts in the zonal location of deep convection in the western Pacific - which drive rainfall δ18O variations of up to 6-8‰ - we perform similar investigations during the weak-to-moderate and moderate-to-strong ENSO cycles of 2006-2008 and 2009-2011 respectively. With this study, we identify the relative influence of local moist processes as well as meridional and zonal shifts in regional hydrology on past western Pacific

  14. Climate Change Decision Making in the Water User Community: Assessment Needs for Projections from Interannual to Multi-Decadal Scales

    NASA Astrophysics Data System (ADS)

    Behar, D.; Adams, A.; Schneiderman, E.; Kaatz, L.

    2012-12-01

    Water managers are increasingly using climate science tools, including model output, in assessing the potential effects of climate change on their operations, infrastructure, and levels of service. The Water Utility Climate Alliance (WUCA), ten large metropolitan utilities providing drinking water to 43 million Americans, has developed relationships individually and collectively across the scientific, agency, and boundary organization communities in pursuit of an understanding of what the current science tells us about the threat of climate change and how to incorporate that understanding into planning. Many WUCA agencies, including those of the authors, have completed or are in the process of completing state-of-the-art assessments using climate model output, expert elicitation, and their own internal modeling tools. A WUCA initiative, Piloting Utility Modeling Applications for Climate Change (PUMA), is facilitating collaboration between five water utilities, four climate science consortiums, and a Modeling Advisory Committee in the preparation of climate change assessments. For WUCA members, and likely others in the adaptation community, the need is for "actionable science," a term WUCA began using in 2008 that was included as an objective in the recently released strategic plan for U.S. Global Change Research Program. Ultimately, assessments feed into existing utility planning processes that look into a future that ranges in scope from years to decades in order to provide guidance on adaptation measures that may be needed. This talk will use WUCA member experiences as case studies to zero in on utility needs for information at these scales, the form of data that best fits with our downstream models (hydrologic, planning), and on the challenges of planning in an atmosphere of uncertainty.

  15. Climatic controls on the interannual to decadal variability in Saudi Arabian dust activity: Toward the development of a seasonal dust prediction model

    NASA Astrophysics Data System (ADS)

    Yu, Yan; Notaro, Michael; Liu, Zhengyu; Wang, Fuyao; Alkolibi, Fahad; Fadda, Eyad; Bakhrjy, Fawzieh

    2015-03-01

    The observed climatic controls on springtime and summertime Saudi Arabian dust activities during 1975-2012 are analyzed, leading to development of a seasonal dust prediction model. According to empirical orthogonal function analysis, dust storm frequency exhibits a dominantly homogeneous pattern across Saudi Arabia, with distinct interannual and decadal variability. The previously identified positive trend in remotely sensed aerosol optical depth since 2000 is shown to be a segment of the decadal oscillation in dust activity, according to long-duration station record. Regression and correlation analyses reveal that the interannual variability in Saudi Arabian dust storm frequency is regulated by springtime rainfall across the Arabian Peninsula and summertime Shamal wind intensity. The key drivers of Saudi Arabian dust storm variability are identified. Winter-to-spring La Niña enhances subsequent spring dust activity by decreasing rainfall across the country's primary dust source region, the Rub' al Khali Desert. A relatively cool tropical Indian Ocean favors frequent summer dust storms by producing an anomalously anticyclonic circulation over the central Arabian Peninsula, which enhances the Shamal wind. Decadal variability in Saudi Arabian dust storm frequency is associated with North African rainfall and Sahel vegetation, which regulate African dust emissions and transport to Saudi Arabia. Mediterranean sea surface temperatures (SSTs) also regulate decadal dust variability, likely through their influence on Sahel rainfall and Shamal intensity. Using antecedent-accumulated rainfall over the Arabian Peninsula and North Africa, and Mediterranean SSTs, as low-frequency predictors, and tropical eastern Pacific and tropical Indian Ocean SSTs as high-frequency predictors, Saudi Arabia's seasonal dust activity is well predicted.

  16. 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

  17. Modelling the interannual variability (1979-2012) of the Mediterranean open-sea deep convection using a coupled regional climate system model

    NASA Astrophysics Data System (ADS)

    Somot, Samuel; Testor, Pierre; Durrieu de Madron, Xavier; Houpert, Loic; Herrmann, Marine; Dubois, Clotilde; Sevault, Florence

    2013-04-01

    The North-Western Mediterranean Sea is known as one of the only place in the world where open-sea deep convection occurs (often up to more than 2000m) with the formation of the Western Mediterranean Deep Water (WMDW). This phenomena is mostly driven by local preconditioning of the water column and strong buoyancy losses during Winter. At the event scale, the WMDW formation is characterized by different phases (preconditioning, strong mixing, restratification and spreading), intense air-sea interaction and strong meso-scale activity but, on a longer time scale, it also shows a large interannual variability and may be strongly affected by climate change with impact on the regional biogeochemistry. Therefore simulating and understanding the temporal variability of the North-Western Mediterranean open-sea deep convection is considered as quite a challenging task for the ocean and climate modelling community. Achieving such a goal requires to work with high resolution models for the ocean and the atmosphere interacting freely and to run long-term and temporally homogeneous simulations with a realistic chronology. In agreement with this statement, we developed at Meteo-France / CNRM a Mediterranean Regional Climate System Model (RCSM) that includes high-resolution representation of the regional atmosphere, land surface, rivers and ocean. The various components are respectively ALADIN (50 km), ISBA (50 km), TRIP (50 km) and NEMO-MED8 (10 km). All the components are interactively coupled daily and a simulation over the period 1979-2012 has been performed using the atmosphere ERA-Interim reanalysis and the ocean NEMOVAR1° reanalysis as 3D lateral-boundary conditions. Spectral nudging technique is applied in the atmosphere. We first evaluate the ability of this model to simulate some of the observed WMDW formation events (air-sea flux, timing, water mass characteristics, deep water formation rate) thanks to the large observational efforts recently carried out to better

  18. Interannual and seasonal dynamics, and the age, of nonstructural carbohydrate pools in the stemwood of temperate trees across a climatic gradient in New England

    NASA Astrophysics Data System (ADS)

    Richardson, A. D.; Carbone, M. S.; Czimczik, C. I.; Keenan, T. F.; Schaberg, P.; Xu, X.

    2011-12-01

    Like all plants, forest trees accumulate and store surplus mobile carbon (C) compounds as resources to be used to support future growth. This can be viewed as a bet-hedging strategy, providing reserves that the tree can draw on in times of stress-e.g., following disturbance, disease, or extreme climatic events. In the context of climate change, understanding factors influencing the availability of these stored C compounds to support growth and metabolism is essential for predicting the resilience of forests to environmental stress factors. We conducted this study to investigate the role of these stored C pools in the context ecosystem C balance at time scales from days to years. At quarterly intervals over a three year period, we monitored stemwood total nonstructural carbohydrate (TNC) concentrations of the dominant tree species of New England. Work was conducted at three sites along a climatic gradient: an oak-dominated transition hardwood forest (Harvard Forest), a maple-beech-birch northern hardwood forest (Bartlett Experimental Forest), and a spruce-fir forest (Howland Forest). We observed large differences among species both in TNC concentrations, and in how the TNC pool is partitioned to different compounds (starch, sucrose, glucose, fructose, raffinose, xylose and stachyose). Within a species, however, seasonal dynamics were remarkably similar across sites. The interannual variability in maximum TNC concentrations appears to be smaller than interannual variability in annual net ecosystem exchange of CO2. With an additional set of samples, we are using the bomb radiocarbon (14C) spike to estimate the average age of the sugars and starches in the TNC pool, and relating this to factors such as size, age, and recent growth rates of each tree. Initial results suggest that these TNC pools range in age from several years to several decades old. The average ages of starch and sugar pools are related, with the starches generally being older than sugars

  19. Glacioclimatological study of perennial ice in the Fuji Ice Cave, Japan. Part 2. Interannual variation and relation to climate

    SciTech Connect

    Ohata, Tetsuo; Furukawa, Teruo; Osada, Kazuo )

    1994-08-01

    A glacioclimatological study of the interannual variation of mass of perennial ice in the Fuji Ice Cave at the foot of Mt. Fuji, in central Japan is presented. The cave is a 150-m-long lava tube located in a dense forest area at an altitude of 1120 m. It has a perennial floor ice of areas approximately 3000 m[sup 3] and mean thickness 2.8 m. Mean annual air temperature at the ground surface level is 8.4[degrees]C. Ice surface levels and air temperatures were measured 39 times from July 1984 to December 1992. Mean ice level showed a 15 cm increase from 1984 to 1989 and suddenly started to decrease from 1989 to 1992. In the increase stage, annual net balance (December to November) was similar at various points, but in the decreasing stage, the lowering of the level near the entrance was very large due to intense melting. Air temperature inside the cave at the end of the annual cycle showed a correlation to net balance of the corresponding year. Comparison of yearly net balance with meterological indices at ground level (winter and summer, annual mean air temperature and total precipitation; and number of days with strong precipitation) showed that net balance of a give year has a high correlation with the average winter air temperature anomaly of the preceding 4 yr. This is probably due to the high heat capacity of the cave system. 6 refs., 7 figs., 2 tabs.

  20. Robust signals of future projections of Indian summer monsoon rainfall by IPCC AR5 climate models: Role of seasonal cycle and interannual variability

    NASA Astrophysics Data System (ADS)

    Jayasankar, C. B.; Surendran, Sajani; Rajendran, Kavirajan

    2015-05-01

    Coupled Model Intercomparison Project phase 5 (Fifth Assessment Report of Intergovernmental Panel on Climate Change) coupled global climate model Representative Concentration Pathway 8.5 simulations are analyzed to derive robust signals of projected changes in Indian summer monsoon rainfall (ISMR) and its variability. Models project clear future temperature increase but diverse changes in ISMR with substantial intermodel spread. Objective measures of interannual variability (IAV) yields nearly equal chance for future increase or decrease. This leads to discrepancy in quantifying changes in ISMR and variability. However, based primarily on the physical association between mean changes in ISMR and its IAV, and objective methods such as k-means clustering with Dunn's validity index, mean seasonal cycle, and reliability ensemble averaging, projections fall into distinct groups. Physically consistent groups of models with the highest reliability project future reduction in the frequency of light rainfall but increase in high to extreme rainfall and thereby future increase in ISMR by 0.74 ± 0.36 mm d-1, along with increased future IAV. These robust estimates of future changes are important for useful impact assessments.

  1. Divergence maintained by climatic selection despite recurrent gene flow: a case study of Castanopsis carlesii (Fagaceae).

    PubMed

    Sun, Ye; Surget-Groba, Yann; Gao, Shaoxiong

    2016-09-01

    Local adaptation to different environments has the potential to maintain divergence between populations despite recurrent gene flow and is an important driver for generating biological diversity. In this study, we investigate the role of adaptation in the maintenance of two parapatric varieties of a forest tree. We used sequence variation of chloroplastic DNA and restriction site-associated DNA to investigate the genetic structure of two varieties of Castanopsis carlesii in subtropical China and relate it to climatic variation. We used niche reconstruction methods to investigate niche differentiation between the two varieties and to estimate the past distribution of this species. A deep divergence was observed between the two varieties, but evidence of introgression and genetic admixture was detected in two phenotypically and geographically intermediate populations. Niche reconstruction suggests that the distribution of the two varieties was disjunct during periods of global cooling and that the two varieties occupy significantly different niches. The genetic structure was mainly driven by environmental factors, and 13 outlier loci under divergent selection were correlated with climatic variation. These results suggest that the two varieties evolved in allopatry and came back into secondary contact after the last glacial maximum and that they are an evolutionary example of divergence maintained by climatic selection despite recurrent gene flow.

  2. Enhanced interannual precipitation variability increases plant functional diversity that in turn ameliorates negative impact on productivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although precipitation interannual variability is projected to increase due to climate change, effects of changes in precipitation variance have received considerable less attention than effects of changes in the mean state of climate. Interannual precipitation variability effects on functional dive...

  3. NDVI indicated long-term interannual changes in vegetation activities and their responses to climatic and anthropogenic factors in the Three Gorges Reservoir Region, China.

    PubMed

    Wen, Zhaofei; Wu, Shengjun; Chen, Jilong; Lü, Mingquan

    2017-01-01

    Natural and social environmental changes in the China's Three Gorges Reservoir Region (TGRR) have received worldwide attention. Identifying interannual changes in vegetation activities in the TGRR is an important task for assessing the impact these changes have on the local ecosystem. We used long-term (1982-2011) satellite-derived Normalized Difference Vegetation Index (NDVI) datasets and climatic and anthropogenic factors to analyze the spatiotemporal patterns of vegetation activities in the TGRR, as well as their links to changes in temperature (TEM), precipitation (PRE), downward radiation (RAD), and anthropogenic activities. At the whole TGRR regional scale, a statistically significant overall uptrend in NDVI variations was observed in 1982-2011. More specifically, there were two distinct periods with different trends split by a breakpoint in 1991: NDVI first sharply increased prior to 1991, and then showed a relatively weak rate of increase after 1991. At the pixel scale, most parts of the TGRR experienced increasing NDVI before the 1990s but different trend change types after the 1990s: trends were positive in forests in the northeastern parts, but negative in farmland in southwest parts of the TGRR. The TEM warming trend was the main climate-related driver of uptrending NDVI variations pre-1990s, and decreasing PRE was the main climate factor (42%) influencing the mid-western farmland areas' NDVI variations post-1990s. We also found that anthropogenic factors such as population density, man-made ecological restoration, and urbanization have notable impacts on the TGRR's NDVI variations. For example, large overall trend slopes in NDVI were more likely to appear in TGRR regions with large fractions of ecological restoration within the last two decades. The findings of this study may help to build a better understanding of the mechanics of NDVI variations in the periods before and during TGDP construction for ongoing ecosystem monitoring and assessment in the

  4. Satellite-measured interannual variability of turbid river plumes off central-southern Chile: Spatial patterns and the influence of climate variability

    NASA Astrophysics Data System (ADS)

    Saldías, Gonzalo S.; Largier, John L.; Mendes, Renato; Pérez-Santos, Iván; Vargas, Cristian A.; Sobarzo, Marcus

    2016-08-01

    Ocean color imagery from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard the Aqua platform is used to characterize the interannual variability of turbid river plumes off central-southern Chile. Emphasis is placed on the influence of climate fluctuations, namely El Niño Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO), and the Antarctic Oscillation (AAO). Additional satellite data on wind, boat-based hydrographic profiles, and regional climate indices are used to identify the influence of climate variability on the generation of anomalous turbid river plumes. The evolution of salinity at a coastal station on the 90 m isobath between the Itata and Biobío Rivers shows a freshwater surface layer with salinity < 32.5 and 5-10 m thick during major plume events in 2002, 2005 and 2006. Surface salinity minima are correlated with peaks in turbidy from the normalized water leaving radiance at 555 nm (nLw(555)), both representing turbid river plumes. EOF analysis reveals that major turbid plume events occurred primarily during warm phases of the ENSO and PDO, and negative phases of the AAO, when storm tracks are further north. Anomalously large turbid plumes extend long distances offshore (∼ 70-80 km), and individual plumes coalesce into a continuous plume along the coast that covers the entire continental shelf. Season-specific correlation analyses reveal an increased influence of the AAO on river plumes south of Punta Lavapié in spring-summer (negative correlation). North of this major cape, ENSO and PDO indices have a dominant influence on plumes with positive correlations with the nLw(555) signal in winter (and negative in summer). We discuss the biogeochemical implications of plume events and the importance of long-term and high-resolution ocean color observations for studying the temporal evolution of river plumes.

  5. Climatically induced interannual variability in aboveground production in forest-tundra and northern taiga of central Siberia.

    PubMed

    Knorre, Anastasia A; Kirdyanov, Alexander V; Vaganov, Eugene A

    2006-02-01

    To investigate the variability of primary production of boreal forest ecosystems under the current climatic changes, we compared the dynamics of annual increments and productivity of the main components of plant community (trees, shrubs, mosses) at three sites in the north of Siberia (Russia). Annual radial growth of trees and shrubs was mostly defined by summer temperature regime (positive correlation), but climatic response of woody plants was species specific and depends on local conditions. Dynamics of annual increments of mosses were opposite to tree growth. The difference in climatic response of the different vegetation components of the forest ecosystems indicates that these components seem to be adapted to use climatic conditions during the short and severe northern summer, and decreasing in annual production of one component is usually combined with the increase of other component productivity. Average productivity in the northern forest ecosystems varies from 0.05 to 0.14 t ha(-1) year(-1) for trees, from 0.05 to 0.18 t ha(-1) year(-1) for shrubs and from 0.54 to 0.66 t ha(-1) year(-1) for mosses. Higher values of tree productivity combined with lower annual moss productivity were found in sites in northern taiga in comparison with forest-tundra. Different tendencies in the productivity of the dominant species from each vegetation level (trees, shrubs, mosses) were indicated for the last 10 years studied (1990-1999): while productivity of mosses is increasing, productivity of trees is decreasing, but there is no obvious trend in the productivity of shrubs. Our results show that in the long term, the main contribution to changes in annual biomass productivity in forest-tundra and northern taiga ecosystems under the predicted climatic changes will be determined by living ground cover.

  6. 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.

  7. Evaluating and Quantifying the Climate-Driven Interannual Variability in Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI3g) at Global Scales

    NASA Technical Reports Server (NTRS)

    Zeng, Fanwei; Collatz, George James; Pinzon, Jorge E.; Ivanoff, Alvaro

    2013-01-01

    Satellite observations of surface reflected solar radiation contain informationabout variability in the absorption of solar radiation by vegetation. Understanding thecauses of variability is important for models that use these data to drive land surface fluxesor for benchmarking prognostic vegetation models. Here we evaluated the interannualvariability in the new 30.5-year long global satellite-derived surface reflectance index data,Global Inventory Modeling and Mapping Studies normalized difference vegetation index(GIMMS NDVI3g). Pearsons correlation and multiple linear stepwise regression analyseswere applied to quantify the NDVI interannual variability driven by climate anomalies, andto evaluate the effects of potential interference (snow, aerosols and clouds) on the NDVIsignal. We found ecologically plausible strong controls on NDVI variability by antecedent precipitation and current monthly temperature with distinct spatial patterns. Precipitation correlations were strongest for temperate to tropical water limited herbaceous systemswhere in some regions and seasons 40 of the NDVI variance could be explained byprecipitation anomalies. Temperature correlations were strongest in northern mid- to-high-latitudes in the spring and early summer where up to 70 of the NDVI variance was explained by temperature anomalies. We find that, in western and central North America,winter-spring precipitation determines early summer growth while more recent precipitation controls NDVI variability in late summer. In contrast, current or prior wetseason precipitation anomalies were correlated with all months of NDVI in sub-tropical herbaceous vegetation. Snow, aerosols and clouds as well as unexplained phenomena still account for part of the NDVI variance despite corrections. Nevertheless, this study demonstrates that GIMMS NDVI3g represents real responses of vegetation to climate variability that are useful for global models.

  8. Vegetation dynamics and climate seasonality jointly control the interannual catchment water balance in the Loess Plateau under the Budyko framework

    NASA Astrophysics Data System (ADS)

    Ning, Tingting; Li, Zhi; Liu, Wenzhao

    2017-03-01

    Within the Budyko framework, the controlling parameter (ω in the Fu equation) is widely considered to represent landscape conditions in terms of vegetation coverage (M); however, some qualitative studies have concluded that climate seasonality (S) should be incorporated in ω. Here, we discuss the relationship between ω, M, and S, and further develop an empirical equation so that the contributions from M to actual annual evapotranspiration (ET) can be determined more accurately. Taking 13 catchments in the Loess Plateau as examples, ω was found to be well correlated with M and S. The developed empirical formula for ω calculations at the annual scale performed well for estimating ET by the cross-validation approach. By combining the Budyko framework with the semi-empirical formula, the contributions of changes in ω to ET variations were further decomposed as those of M and S. Results showed that the contributions of S to ET changes ranged from 0.1 to 74.8 % (absolute values). Therefore, the impacts of climate seasonality on ET cannot be ignored, otherwise the contribution of M to ET changes will be estimated with a large error. The developed empirical formula between ω, M, and S provides an effective method to separate the contributions of M and S to ET changes.

  9. Effects of Interannual Climate Variability on Water Availability and Productivity in Capoeira and Crops Under Traditional and Alternative Shifting Cultivation

    NASA Technical Reports Server (NTRS)

    Guild, Liane S.; Sa, Tatiana D. A.; Carvalho, Claudio J. R.; Potter, Christopher S.; Wickel, Albert J.; Brienza, Silvio, Jr.; Kato, Maria doSocorro A.; Kato, Osvaldo; Brass, James (Technical Monitor)

    2002-01-01

    Regenerating forests play an important role in long-term carbon sequestration and sustainable landuse as they act as potentially important carbon and nutrient sinks during the shifting agriculture fallow period. The long-term functioning of capoeira. is increasingly threatened by a shortening fallow period during shifting cultivation due to demographic pressures and associated increased vulnerability to severe climatic events. Declining productivity and functioning of fallow forests of shifting cultivation combined with progressive loss of nutrients by successive burning and cropping activities has resulted in declining agricultural productivity. In addition to the effects of intense land use practices, droughts associated with El Nino events are becoming more frequent and severe in moist tropical forests and negative effects on capoeira productivity could be considerable. In Igarape-Acu (near Belem, Para), we hypothesize that experimental alternative landuse/clearing practices (mulching and fallow vegetation improvement by planting with fast-growing leguminous tree species) may make capoeira and agriculture more resilient to the effects of agricultural pressures and drought through (1) increased biomass, soil organic matter and associated increase in soil water storage, and nutrient retention and (2) greater rooting depth of trees planted for fallow improvement. This experimental practice (moto mechanized chop-and-mulch with fallow improvement) has resulted increased soil moisture during the cropping phase, reduced loss of nutrients and organic matter, and higher rates of secondary-forest biomass accumulation. We present preliminary data on water relations during the dry season of 2001 in capoeira and crops for both traditional slash-and-burn and alternative chop-and-mulch practices. These data will be used to test IKONOS data for the detection of moisture status differences. The principal goal of the research is to determine the extent to which capoeira and

  10. Quantifying the effect of interannual ocean variability on the attribution of extreme climate events to human influence

    NASA Astrophysics Data System (ADS)

    Risser, Mark D.; Stone, Dáithí A.; Paciorek, Christopher J.; Wehner, Michael F.; Angélil, Oliver

    2017-01-01

    In recent years, the climate change research community has become highly interested in describing the anthropogenic influence on extreme weather events, commonly termed "event attribution." Limitations in the observational record and in computational resources motivate the use of uncoupled, atmosphere/land-only climate models with prescribed ocean conditions run over a short period, leading up to and including an event of interest. In this approach, large ensembles of high-resolution simulations can be generated under factual observed conditions and counterfactual conditions that might have been observed in the absence of human interference; these can be used to estimate the change in probability of the given event due to anthropogenic influence. However, using a prescribed ocean state ignores the possibility that estimates of attributable risk might be a function of the ocean state. Thus, the uncertainty in attributable risk is likely underestimated, implying an over-confidence in anthropogenic influence. In this work, we estimate the year-to-year variability in calculations of the anthropogenic contribution to extreme weather based on large ensembles of atmospheric model simulations. Our results both quantify the magnitude of year-to-year variability and categorize the degree to which conclusions of attributable risk are qualitatively affected. The methodology is illustrated by exploring extreme temperature and precipitation events for the northwest coast of South America and northern-central Siberia; we also provides results for regions around the globe. While it remains preferable to perform a full multi-year analysis, the results presented here can serve as an indication of where and when attribution researchers should be concerned about the use of atmosphere-only simulations.

  11. Masking of interannual climate proxy signals by residual tropical cyclone rainwater: Evidence and challenges for low-latitude speleothem paleoclimatology

    NASA Astrophysics Data System (ADS)

    Frappier, Amy Benoit

    2013-09-01

    The anomalously low oxygen isotope ratio (δ18O values) of tropical cyclone rainfall can transfer proxy information about past tropical cyclone activity to stalagmite oxygen isotope records. Isotopically distinct stormwater reaches the growing crystal surface as a coherent slug, or after attenuation by mixing with isotopically normal vadose groundwaters. A high-resolution micromilled stalagmite stable isotope record from Belize shows that residual tropical cyclone water from Hurricane Mitch masked the oxygen isotope record of a major El Niño event. On decadal time scales, measured δ18O values are affected by changes in local tropical cyclone frequency. Despite the tropical cyclone masking effect, the structure of the "missing" El Niño event is preserved in the ATM-7 carbon isotope ratios (δ13C values). In tropical cyclone-prone regions, the fidelity of stalagmite oxygen isotope proxy data to recording background climate signals is modulated by temporal variations in local tropical cyclone rainfall, and the sensitivity of individual stalagmites to tropical cyclone masking varies with hydrology. Speleothem δ13C values, unaffected by tropical cyclones, can preserve the underlying structure of climatic variability. For low-latitude speleothems with C-O isotope covariance, intervals in which the δ18O values are significantly lower than δ13C values predict may indicate periods when local tropical cyclone masking of isotope-derived precipitation records is enhanced by greater infiltration of tropical cyclone rain. The temporal structure in stalagmite C-O isotope covariance has paleoenvironmental meaning that may be revealed by exploring factors associated with independent behavior in each isotope ratio, respectively. Tropical cyclone masking presents new challenges to paleoclimatology and a source of hypotheses for paleotempestology.

  12. Detection of Interannual Climate Variability in Secondary Forests and Crops Under Traditional and Alternative Shifting Cultivation Using Ikonos Data

    NASA Astrophysics Data System (ADS)

    Sa, T.; Guild, L.; Carvalho, C.; Wickel, A.; Brienza, S.; Kato, M.; Kato, O.; Leibs, C.

    2004-12-01

    Regenerating forests play an important role in long-term carbon sequestration and sustainable landuse as they act as potentially important carbon and nutrient sinks during the shifting agriculture fallow period. The long-term functioning of secondary forests (capoeira) is increasingly threatened by a shortening fallow period during shifting cultivation due to demographic pressures and associated increased vulnerability to severe climatic events. Declining productivity and functioning of fallow forests of shifting cultivation combined with progressive loss of nutrients by successive burning and cropping activities has resulted in declining agricultural productivity. In addition to the effects of intense land use practices, droughts associated with El Nino events are becoming more frequent and severe in moist tropical forests and negative effects on capoeira productivity could be considerable. The principal goal of the research is to determine the extent to which capoeira and agricultural fields are susceptible to extreme climate events (drought) under contrasting landuse/clearing practices. In Igarape-Açu (near Belem, Para), we hypothesize that experimental alternative landuse/clearing practices (mulching) may make capoeira and crops more resilient to the effects of agricultural pressures and drought through increased biomass, soil organic matter and associated increase in soil water storage, and nutrient retention. This experimental practice (mechanized chop-and-mulch) has resulted in increased soil moisture during the cropping phase, reduced loss of nutrients and organic matter, and higher rates of secondary-forest biomass accumulation. This project aims to measure water availability and it's relation to secondary forest and crop productivity in the Brazilian Amazon. We have conducted field efforts during two dry seasons (August-December). Field data on water relations were collected during the dry season of 2001 and 2002 in capoeira and crops for both

  13. Interannual to Decadal Variability in Climate and the Glacier Mass Balance in Washington, Western Canada, and Alaska*.

    NASA Astrophysics Data System (ADS)

    Bitz, C. M.; Battisti, D. S.

    1999-11-01

    The authors examine the net winter, summer, and annual mass balance of six glaciers along the northwest coast of North America, extending from Washington State to Alaska. The net winter (NWB) and net annual (NAB) mass balance anomalies for the maritime glaciers in the southern group, located in Washington and British Columbia, are shown to be positively correlated with local precipitation anomalies and storminess (defined as the rms of high-passed 500-mb geopotential anomalies) and weakly and negatively correlated with local temperature anomalies. The NWB and NAB of the maritime Wolverine glacier in Alaska are also positively correlated with local precipitation, but they are positively correlated with local winter temperature and negatively correlated with local storminess. Hence, anomalies in mass balance at Wolverine result mainly from the change in moisture that is being advected into the region by anomalies in the averaged wintertime circulation rather than from a change in storminess. The patterns of the wintertime 500-mb circulation and storminess anomalies associated with years of high NWB in the southern glacier group are similar to those associated with low NWB years at the Wolverine glacier, and vice versa.The decadal ENSO-like climate phenomenon discussed by Zhang et al. has a large impact on the NWB and NAB of these maritime glaciers, accounting for up to 35% of the variance in NWB. The 500-mb circulation and storminess anomalies associated with this decadal ENSO-like mode resemble the Pacific-North American pattern, as do 500-mb composites of years of extreme NWB of South Cascade glacier in Washington and of Wolverine glacier in Alaska. Hence, the decadal ENSO-like mode affects precipitation in a crucial way for the NWB of these glaciers. Specifically, the decadal ENSO-like phenomenon strongly affects the storminess over British Columbia and Washington and the moisture transported by the seasonally averaged circulation into maritime Alaska. In contrast

  14. A unifying view of climate change in the Sahel linking intra-seasonal, interannual and longer time scales

    NASA Astrophysics Data System (ADS)

    Giannini, A.; Salack, S.; Lodoun, T.; Ali, A.; Gaye, A. T.; Ndiaye, O.

    2013-06-01

    We propose a re-interpretation of the oceanic influence on the climate of the African Sahel that is consistent across observations, 20th century simulations and 21st century projections, and that resolves the uncertainty in projections of precipitation change in this region: continued warming of the global tropical oceans increases the threshold for convection, potentially drying tropical land, but this ‘upped ante’ can be met if sufficient moisture is supplied in monsoon flow. In this framework, the reversal to warming of the subtropical North Atlantic, which is now out-pacing warming of the global tropical oceans, provides that moisture, and explains the partial recovery in precipitation since persistent drought in the 1970s and 1980s. We find this recovery to result from increases in daily rainfall intensity, rather than in frequency, most evidently so in Senegal, the westernmost among the three Sahelian countries analyzed. Continuation of these observed trends is consistent with projections for an overall wetter Sahel, but more variable precipitation on all time scales, from intra-seasonal to multi-decadal.

  15. Use of color maps and wavelet coherence to discern seasonal and interannual climate influences on streamflow variability in northern catchments

    NASA Astrophysics Data System (ADS)

    Carey, Sean K.; Tetzlaff, Doerthe; Buttle, Jim; Laudon, Hjalmar; McDonnell, Jeff; McGuire, Kevin; Seibert, Jan; Soulsby, Chris; Shanley, Jamie

    2013-10-01

    The higher midlatitudes of the northern hemisphere are particularly sensitive to change due to the important role the 0°C isotherm plays in the phase of precipitation and intermediate storage as snow. An international intercatchment comparison program called North-Watch seeks to improve our understanding of the sensitivity of northern catchments to change by examining their hydrological and biogeochemical variability and response. Here eight North-Watch catchments located in Sweden (Krycklan), Scotland (Girnock and Strontian), the United States (Sleepers River, Hubbard Brook, and HJ Andrews), and Canada (Dorset and Wolf Creek) with 10 continuous years of daily precipitation and runoff data were selected to assess daily to seasonal coupling of precipitation (P) and runoff (Q) using wavelet coherency, and to explore the patterns and scales of variability in streamflow using color maps. Wavelet coherency revealed that P and Q were decoupled in catchments with cold winters, yet were strongly coupled during and immediately following the spring snowmelt freshet. In all catchments, coupling at shorter time scales occurred during wet periods when the catchment was responsive and storage deficits were small. At longer time scales, coupling reflected coherence between seasonal cycles, being enhanced at sites with enhanced seasonality in P. Color maps were applied as an alternative method to identify patterns and scales of flow variability. Seasonal versus transient flow variability was identified along with the persistence of that variability on influencing the flow regime. While exploratory in nature, this intercomparison exercise highlights the importance of climate and the 0°C isotherm on the functioning of northern catchments.

  16. Interannual climate variability and spatially heterogeneous improvement of agricultural management impede detection of a decreasing trend in nitrate pollution in an agricultural catchment

    NASA Astrophysics Data System (ADS)

    Fovet, Ophélie; Dupas, Rémi; Durand, Patrick; Gascuel-Odoux, Chantal; Gruau, Gérard; Hamon, Yannick; Petitjean, Patrice

    2016-04-01

    Despite widespread implementation of the nitrate directive in the European Union since the 1990s, the impact on nitrate concentration in rivers is limited (Bouraoui and Grizzetti, 2011). To assess whether this lack of response is due to the long time lags of nitrate transfer or to inadequate programs of measure, long term river and groundwater monitoring data are necessary. This study analyses 15 years of daily nitrate concentration data at the outlet of an intensively farmed catchment in Western France (Kervidy-Naizin, 5 km²) and quarterly nitrate concentration data in the groundwater of two hillslopes equipped with piezometers (Kerroland and Gueriniec) within the same catchment. In this catchment groundwater contribution to annual stream flow is dominant. The objectives of this study were to i) disentangle the influence of interannual climate variability and improvement of agricultural practices (i.e. reduction in N surplus) in the stream chemistry and ii) discuss the reasons for slow catchment recovery from nitrate pollution by comparing trends in groundwater and stream concentrations. Analysis of stream data showed that flow-weighted mean annual concentration at the outlet of the Kervidy-Naizin catchment has decreased by 1.2 mg NO3- l-1 yr-1 from 1999 to 2015. This decrease was slow but significant (p value < 0.01) even though interannual climate variability (i.e. annual cumulated runoff) added noise to the signal: i) deviation in the linear model of nitrate decrease with time was negatively correlated with annual runoff (r = -0.54, p < 0.01) and ii) local minimums in the nitrate time series were coincident with local maximums in the annual runoff. Thus high runoff during wet years led to dilution of the nitrate originating from groundwater, which added variability to the signal of linear decrease in stream concentration. Analysis of groundwater data showed a significant and sharp decrease in nitrate concentration in the Kerroland piezometer transect (4.0 mg

  17. 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.

  18. The 1994 heat wave in South Korea: mortality impacts and recurrence probability in a changing climate

    NASA Astrophysics Data System (ADS)

    Kysely, J.; Kim, J.

    2010-03-01

    The study deals with mortality impacts of the July-August 1994 heat wave in the population of South Korea, including the megacity of Seoul (with the population exceeding 10 million for the city and 20 million for the metropolitan area), and estimates recurrence probability of the heat wave in a changing climate in terms of simulations of daily temperature series with a stochastic model. The 1994 heat wave is found exceptional with respect to both climatological characteristics and the mortality effects: significantly elevated mortality occurred in all population groups, including children up to 14 years of age, and the total death toll exceeded 3000 in the Korean population, which ranks the 1994 heat wave among the worst weather-related disasters in East Asia. The estimate represents net excess mortality as no mortality displacement effect appeared. A comparison with other documented natural disasters shows that the death toll of the heat wave was much higher than those of the most disastrous floodings and typhoons over Korean Peninsula in the 20th century. The mortality response was stronger in males than females although males are found to be less vulnerable during average heat waves. A climatological analysis reveals that the July-August 1994 heat wave might be considered an extremely rare event with a return period in the order of hundreds of years if stationarity of temperature time series is assumed. However, under a more realistic assumption of gradual warming related to climate change, recurrence probability of an event analogous to the 1994 heat wave sharply rises for near-future time horizons. If warming of 0.04°C/year is assumed over 2001-2060, the recurrence interval of a very long spell of days with temperature exceeding a high threshold (as in the 1994 heat wave) is estimated to decrease to around 40 (10) years in the 2021-2030 (2041-2050) decade. This emphasizes the need for setting up an efficient heat-watch-warning system in this area in order to

  19. Forcings of nutrient, oxygen, and primary production interannual variability in the southeast Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bachèlery, M.-L.; Illig, S.; Dadou, I.

    2016-08-01

    The recurrent occurrences of interannual warm and cold events along the coast of Africa have been intensively studied because of their striking effects on climate and fisheries. Using sensitivity experimentation based on a coupled physical/biogeochemical model, we show that the oceanic remote equatorial forcing explains more than 85% of coastal interannual nitrate and oxygen fluctuations along the Angolan and Namibian coasts up to the Benguela Upwelling System (BUS). These events, associated with poleward propagations of upwelling and downwelling Coastal Trapped Waves (CTW), are maximum in subsurface and controlled by physical advection processes. Surprisingly, an abrupt change in the CTW biogeochemical signature is observed in the BUS, associated with mixed vertical gradients due to the strong local upwelling dynamics. Coastal modifications of biogeochemical features result in significant primary production variations that may affect fisheries habitats and coastal biodiversity along the southwestern African coasts and in the BUS.

  20. Possible link between interannual variation of neon flying squid (Ommastrephes bartramii) abundance in the North Pacific and the climate phase shift in 1998/1999

    NASA Astrophysics Data System (ADS)

    Igarashi, Hiromichi; Ichii, Taro; Sakai, Mitsuo; Ishikawa, Yoichi; Toyoda, Takahiro; Masuda, Shuhei; Sugiura, Nozomi; Mahapatra, Kedarnath; Awaji, Toshiyuki

    2017-01-01

    The relationship between interannual variation in abundance of the autumn cohort of the neon flying squid (Ommastrephes bartramii) and ocean environmental changes in the central North Pacific was examined. We focused on the change in subsurface ocean state during the 1998/1999 climate shift. Changes in catch per unit effort (CPUE) of the neon flying squid derived from long-term driftnet survey was compared to that in ocean environments related to the feeding conditions of the squid. A four-dimensional variational (4D-VAR) ocean data assimilation product was used as an accurate estimate of the dynamic state in the North Pacific. Correlation analysis indicated that the squid CPUE was highly related with the Pacific Decadal Oscillation (PDO) in winter. In January, the correlation field with the entrainment rate (ENT), the proxy for the nutrient-rich water supply entering the mixed layer, showed a good agreement with the main spawning and nursery ground of the autumn cohort (MSNGAC). The nutrient-rich water supply in the MSNGAC in early winter was mainly induced by the deepening of the mixed layer forced by surface latent heat cooling and turbulent mixing, while the basin-scale wind stress curl and the horizontal advection were less affected. These results suggest that the amount of newly supplied nutrient-rich water mass in early winter could affect the primary productivity throughout the winter and the resultant feeding conditions of the juvenile squid. We assumed that this process would determine the stock levels of the neon flying squid in the following summer. We further attempted to reconstruct the changes in neon flying squid CPUE during 1994-2006 by applying regression analysis to several parameters. The result showed that ENT, surface and subsurface temperatures, and the PDO index in February were good predictors for estimating the squid CPUE time series. In addition, the subsurface temperature in the MSNGAC in the preceding autumn was also a good predictor

  1. Mars dust storms - Interannual variability and chaos

    NASA Technical Reports Server (NTRS)

    Ingersoll, Andrew P.; Lyons, James R.

    1993-01-01

    The hypothesis is that the global climate system, consisting of atmospheric dust interacting with the circulation, produces its own interannual variability when forced at the annual frequency. The model has two time-dependent variables representing the amount of atmospheric dust in the northern and southern hemispheres, respectively. Absorption of sunlight by the dust drives a cross-equatorial Hadley cell that brings more dust into the heated hemisphere. The circulation decays when the dust storm covers the globe. Interannual variability manifests itself either as a periodic solution in which the period is a multiple of the Martian year, or as an aperiodic (chaotic) solution that never repeats. Both kinds of solution are found in the model, lending support to the idea that interannual variability is an intrinsic property of the global climate system. The next step is to develop a hierarchy of dust-circulation models capable of being integrated for many years.

  2. The relationship between interannual and long-term cloud feedbacks

    SciTech Connect

    Zhou, Chen; Zelinka, Mark D.; Dessler, Andrew E.; Klein, Stephen A.

    2015-12-11

    The analyses of Coupled Model Intercomparison Project phase 5 simulations suggest that climate models with more positive cloud feedback in response to interannual climate fluctuations also have more positive cloud feedback in response to long-term global warming. Ensemble mean vertical profiles of cloud change in response to interannual and long-term surface warming are similar, and the ensemble mean cloud feedback is positive on both timescales. However, the average long-term cloud feedback is smaller than the interannual cloud feedback, likely due to differences in surface warming pattern on the two timescales. Low cloud cover (LCC) change in response to interannual and long-term global surface warming is found to be well correlated across models and explains over half of the covariance between interannual and long-term cloud feedback. In conclusion, the intermodel correlation of LCC across timescales likely results from model-specific sensitivities of LCC to sea surface warming.

  3. Interannual variability of the Arctic freshwater cycle in the second half of the twentieth century in a regionally coupled climate model

    NASA Astrophysics Data System (ADS)

    Niederdrenk, Anne Laura; Sein, Dmitry V.; Mikolajewicz, Uwe

    2016-12-01

    We use a regionally coupled ocean-sea ice-atmosphere-hydrological discharge model to investigate the influence of changes in the atmospheric large-scale circulation on the interannual variability of the Arctic freshwater (FW) components. This model includes all sinks and sources of FW and allows for the analysis of a closed FW cycle in the Arctic. We show that few atmospheric winter modes explain large parts of the interannual variability of the Arctic FW cycle. A strong Icelandic low causing anomalous strong westerlies over the North Atlantic leads to warmer and wetter conditions over Eurasia. The ocean circulation is then characterized by a strong transpolar drift leading to increased export of FW in liquid and solid form into the North Atlantic. In contrast to this, a weaker than usual Icelandic low and a strong Siberian high is associated with a strong Beaufort Gyre and thus an accumulation of FW within the Arctic Ocean. Not only specific winter conditions but also increased precipitation in late spring and summer, caused by enhanced cyclone activity over land, lead to increased Eurasian runoff, which is responsible for most of the variability in Arctic river runoff.

  4. Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires

    NASA Astrophysics Data System (ADS)

    Grandey, Benjamin S.; Lee, Hsiang-He; Wang, Chien

    2016-11-01

    Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These "fire aerosols" can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of -1.0 W m-2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (-0.2 W m-2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (-1.2 W m-2), while over Boreal Asia the overestimation is +43 % (-1.9 W m-2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.

  5. Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires

    DOE PAGES

    Grandey, Benjamin S.; Lee, Hsiang-He; Wang, Chien

    2016-11-23

    Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These “fire aerosols” can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of −1.0 W m−2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect ismore » particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (−0.2 W m−2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (−1.2 W m−2), while over Boreal Asia the overestimation is +43 % (−1.9 W m−2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions.« less

  6. Ethical Considerations Regarding the Biological Contamination of Climatically Recurrent Special Regions.

    NASA Astrophysics Data System (ADS)

    Clifford, S. M.

    2014-04-01

    years, such as in the Martian polar layered deposits (and other high-latitude, ice-rich environments), at times of high obliquity. Current climate models suggest that, for obliquities > 45°, summertime surface temperatures at polar and near-polar latitudes may approach or exceed the melting point of water for continuous periods of many months (Costard et al., 2001; Jakosky et al., 2003) - conditions that may be repeated annually throughout the maximum obliquity phase of the 105-year obliquity cycle. If so, these icerich, high-latitude environments may be considered climatically recurrent Special Regions - and may be among the most potentially habitable environments on Mars for the survival and growth of terrestrial microorganisms.A significant concern arising from this potential is that, whether by accident or the nominal operation of investigating spacecraft (cleaned to less than Special Region (IVc) standards), we might irreversibly contaminate these sensitive environments. While such contamination may not pose an immediate threat to the integrity of our spacecraft life-detection experiments, its potential impact on the long-term health and ultimate survival of a native Martian biosphere raises significant scientific and ethical concerns, as identified in the NRC report on Preventing the Forward Contamination 0f Mars [4]. Precedents for considering the adoption of planetary protection standards that minimize the potential impact of our exploration efforts on a native biosphere include the NRC report on Preventing the Forward Contamination of Europa, which noted that "future spacecraft missions to Europa must be subject to procedures designed to prevent its contamination by terrestrial organisms. This is necessary to safeguard the scientific integrity of future studies of Europa's biological potential and to protect against potential harm to Europan organisms, if they exist, and is mandated by obligations under the [Outer Space Treaty]" [5]). Virtually identical

  7. Evaluation of the UK Met Office's HadGEM3-RA and HadRM3P regional climate models within South America-CORDEX simulations: ENSO related interannual precipitation variability

    NASA Astrophysics Data System (ADS)

    Bozkurt, D.; Rojas, M.

    2014-12-01

    This study aims to investigate and compare the ability of the UK Met Office's HadGEM3-RA and HadRM3P regional climate models (RCMs) to simulate mean and interannual variability of precipitation over South America with a special focus on Chile. The HadGEM3-RA is a regional version of the newly developed HadGEM3 global model and the HadRM3P is based on the earlier HadCM3 global model. The RCMs simulations were carried out at 0.44o x 0.44o degree resolution over South America-CORDEX domain for the period 1989-2008. The initial and boundary conditions were provided by ERA-Interim Reanalysis data available at 6-h intervals with a resolution of 1.5o x 1.5o in the horizontal and 37 pressure levels. We compare the results against a number of observational datasets, including gridded dataset of CRU, UDEL, TRMM and GPCP. Moreover, available station data is derived from Direccion General de Aguas (DGA) mainly for Central Chile, which is the heartland of Chile with the highest population and important economic activities. The analysis is mainly focused on evaluating the abilities of the RCMs in simulating spatial pattern and ENSO related precipitation variability in different subregions of South America-CORDEX domain. In general, both RCMs have a good skill in reproducing spatial pattern and annual cycle of observed precipitation in climatically different subregions. However, both RCMs tend to underestimate precipitation in the Amazon Basin, which is more pronounced in the HadRM3P simulations. On the contrary, the RCMs tend to overestimate the precipitation over the Andes and southern Chile. The overestimation could be related to the physical core of the RCMs, but the discrepancies could also arise due to insufficient station network, especially in the mountainous areas, potentially yielding smaller precipitation quantities in the observed data than the true ones. In terms of interannual variability, the models capture ENSO related wet and dry interannual precipitation

  8. Recurrence network-based time series analysis for identifying tipping points in Plio-Pleistocene African climate

    NASA Astrophysics Data System (ADS)

    Donges, J. F.; Donner, R. V.; Trauth, M. H.; Marwan, N.; Schellnhuber, H. J.; Kurths, J.

    2012-04-01

    The analysis of paleoclimate time series is usually affected by severe methodological problems, resulting primarily from non-equidistant sampling and uncertain age models. As an alternative to existing methods of time series analysis, the statistical properties of recurrence networks are promising candidates for characterizing a system's nonlinear dynamics and quantifying structural changes in its reconstructed phase space as time evolves. The results of recurrence network analysis are robust under changes in the age model and are not directly affected by non-equidistant sampling of the data. Specifically, we investigate three marine records of African climate variability during the Plio-Pleistocene. We detect several statistically significant dynamical transitions or tipping points and show that the obtained results are qualitatively robust under changes of the relevant parameters of our method, including detrending, size of the running window used for analysis, and embedding delay. Finally, relating the identified tipping points in paleoclimate-variability to speciation and extinction events in the available fossil record of human ancestors contributes to the understanding of climatic mechanisms driving human evolution in Africa during the past 5 million years.

  9. Effects of Climate Change on Indigenous Livelihoods: The Case of Recurrent Droughts among Nomadic Pastoralist of Southeastern Kenya

    NASA Astrophysics Data System (ADS)

    Mwangi, M. N.; Desanker, P. V.

    2006-12-01

    Drought is the most injurious impact of climate change that decimates lives and hinders socioeconomic development in most rangelands of Kenya. Several scientific evidences indicate that global climate change will increase frequency and intensity of droughts. This will have important ramification for ecosystems and social systems in the rangelands of southeastern Kenya, and correctly so. These rangelands are fragile and degraded; and the inhabitants are mostly poverty-stricken. Nomadic pastoralism is the chief source of livelihood in this region; it relies on local natural pastures. Besides, pressures from land use change constitute an additional exposure, of nomadic pastoralism, to vulnerabilities of this climatic hazard. This region is highly prone to droughts; it is currently recovering from a devastating drought that started in early 2005 and terminated at the start this year. Most important, and like most societies in sub-Saharan Africa, inadequate adaptive capacity among nomadic pastoralists of Kenya, exacerbates deleterious impacts of drought. The livelihood of these pastoralists, therefore, stands to be destabilized. This study presents findings from an on-going research in Kajiado District of southeastern Kenya. Impacts of and adaptation strategies to recurrent and prolonged droughts among the nomadic Maasai pastoralist are presented. The study concludes with possible future scenarios of this form of pastoralism from which climate change actors can draw from.

  10. Recurrent evolution of herbivory in small, cold-climate lizards: breaking the ecophysiological rules of reptilian herbivory.

    PubMed

    Espinoza, Robert E; Wiens, John J; Tracy, C Richard

    2004-11-30

    Herbivory has evolved in many groups of vertebrates, but it is rare among both extinct and extant nonavian reptiles. Among squamate reptiles, (lizards, snakes, and their relatives), <2% of the >7,800 species are considered to be herbivorous, and herbivory is restricted to lizards. Here, we show that within a group of South American lizards (Liolaemidae, approximately 170 species), herbivory has evolved more frequently than in all other squamates combined and at a rate estimated to be >65 times faster. Furthermore, in contrast to other herbivorous lizards and to existing theory, most herbivorous liolaemids are small bodied and live in cool climates. Herbivory is generally thought to evolve only in reptile species that are large bodied, live in warm climates, and maintain high body temperatures. These three well known "rules" of herbivory are considered to form the bases of physiological constraints that explain the paucity of herbivorous reptile species. We suggest that the recurrent and paradoxical evolution of herbivory in liolaemids is explained by a combination of environmental conditions (promoting independent origins of herbivory in isolated cool-climate regions), ecophysiological constraints (requiring small body size in cool climates, yet high body temperatures for herbivores), and phylogenetic history. More generally, our study demonstrates how integrating information from ecophysiology and phylogeny can help to explain macroevolutionary trends.

  11. Changing Climate, Disrupted Livelihoods: The Case of Vulnerability of Nomadic Maasai Pastoralism to Recurrent Droughts in Kajiado District, Kenya

    NASA Astrophysics Data System (ADS)

    Mwangi, M. N.; Desanker, P. V.

    2007-12-01

    Pastoralism is practiced in all arid and semiarid lands (ASALs) of Africa. High interannual rainfall variability and degraded ecosystems characterize these ASALs and limits arable farming. Under these conditions, pastoralism has evolved as the most feasible livelihood system in ASALs, where total annual rainfall correlates with annual net primary productivity, especially grass. Maasai of East Africa are the largest group of nomadic pastoralists in Africa, with about two-thirds living in southern Kenya, mainly in Kajiado and Narok Districts. Maasai people of Kenya subsist by nomadic pastoralism. Nomads migrate with their livestock in search of natural pastures and water as climatic and environmental circumstances mandate. Successful migrations of nomadic pastoralists are being hampered by changing social and ecological factors both at local and broader scales. What is more, increased frequency and duration of drought constitute a major challenge with which the Maasai have to confront. Drought is a slow-developing phenomenon; therefore, it captures delayed attention. Nonetheless, the cumulative impacts of drought are more immense. Drought triggers catastrophic events that diminish adaptive capacity of inhabitants of these ASALs; this is conspicuous in Kajiado District where livestock productivity plummet as resource base erodes. What is more, global climate change is projected to intensify the occurrence, severity and duration of droughts in this region. Frequent droughts are likely to disrupt proper functioning of nomadic Maasai pastoralism. This study presents findings from an integrated research conducted in Kajiado District during the last two years. Spatiotemporal trends of drought, effects of drought on, and possible future of nomadic Maasai pastoralism are presented. This is informative to the Maasai pastoralists, policy makers and other actors in this sector. Most important, the study is contributes toward formulation of informed drought management strategies

  12. Effect of climate, intra and inter-annual variability, on nutrients emission (C,N, P) in stream water: lessons from an agricultural long term observatory of the temperate zone

    NASA Astrophysics Data System (ADS)

    Gascuel-Odoux, Chantal; Remi, Dupas; Patrick, Durand; Ophélie, Fovet; Gerard, Gruau; Anne, Jaffrezic; Guillaume, Humbert; Philippe, Merot; Gu, Sen

    2016-04-01

    Agriculture greatly contributes to modify C, N and P cycles, particularly in animal breeding regions due to high inputs. Climatic conditions, intra and inter-annual variabilities, modify nutrient stream water emissions, acting in time on transfer and transformation, accumulation and mobilization processes, connecting and disconnecting in time different compartments (soil, riparian areas, groundwater). In agricultural catchments, nutrient perturbations are dominated by agricultural land use, and decoupling human activities and climate effects is far from easy. Climate change generally appears as a secondary driver compared to land use. If studied, generally only one nutrient is considered. Only long term, high frequency and multiple element data series can decouple these two drivers. The Kervidy-Naizin watershed belongs to the AgrHyS environmental research observatory (http://www6.inra.fr/ore_agrhys_eng), itself included in RBV (French catchment network of the CZO). On this catchment, 6 years of daily data on DOC, NO3, SRP, TP concentrations allow us to analyze the effect of seasonal and inter-annual climatic variabilities on water quality (C, N, P). Different papers have been published on the effect of climate on nitrate (Molenat et al, 2008), SRP and TP (Dupas et al, 2015) and DOC (Humbert et al, 2015). We will present first results comparing the effect of climate on these three major solute forms of C, N and P. While C and P dynamics are very close and controlled by fluctuation of water table downslope, i.e. in riparian areas, mobilizing C and P in time, nitrate dynamics is controlled by GW dynamics upslope acting as the major N reservoir. As example, the dryness conditions in summer appears a key factor of the C and P emissions in autumn. All the three solute forms interact when anoxic conditions are observed in riparian zones. These basic processes explain how climatic variability can influence and explain interactions between C, N and P emissions in stream

  13. Climate response and spatial-temporal model on the inter-annual change of winter temperature-salinity in the East China Sea

    NASA Astrophysics Data System (ADS)

    Yang, Jin-kun; Miao, Qing-sheng; Yang, Yang; Xu, Shan-shan

    2017-01-01

    Spatial distributions and time variation characteristics were analyzed using Rotated Empirical Orthogonal Function (REOF) and spectrum analysis methods using surface and bottom temperature and salinity data in February of 1976-2013 along 30°N section in the East China Sea. Result showed that temperature trends can be divided into western part and east part, salinity trend divided into western, middle and eastern part. The first mode of surface temperature presented a quasi-equilibrium trend and the range was higher in the near-shore than the offshores, first mode of bottom temperature presented a decreasing trend; surface salinity had a decreasing trend and the extent was higher in the near-shore than the offshores, the bottom salinity showed a decreasing trend in recent years. The temperature inter-annual variability related to El Niño closely; short-term shocks of salinity related to El Niño, and long-term changes had something to do with PDO.

  14. Florida Current: seasonal and interannual variability

    SciTech Connect

    Schott, F.; Zantopp, R.

    1985-01-18

    Annual and interannual variations in the Florida Current, Caribbean and subtropical Atlantic are investigated with the use of historical sea level differences and wind field data. Observational and model evidence suggests that the seasonal transport cycle of the Florida Current is locally forced, either upstream in the Caribbean or downstream over topography. Although at seasonal and shorter periods sea level or bottom pressure fluctuations on the left side of the Florida Current contribute almost all of the variance of sea level difference across the Florida Straits and hence transport, this relation does not seem to apply at interannual time scales. Using results from the Subtropical Atlantic Climate Studies, it is estimated from historical sea level data that interannual transport fluctuations of the Florida Current are only of order 1 x 10/sup 6/ cubic meters per second. Interannual fluctuations in the 2- to 3-year period range in the Florida Straits seem to be correlated with sea level differences across the Caribbean and the subtropical Atlantic but not with Sverdrup transport fluctuations in the subtropical Atlantic. 26 references, 2 figures.

  15. Productivity and phenological responses of natural vegetation to present and future inter-annual climate variability across semi-arid river basins in Chile.

    PubMed

    Glade, Francisco E; Miranda, Marcelo D; Meza, Francisco J; van Leeuwen, Willem J D

    2016-12-01

    Time series of vegetation indices and remotely sensed phenological data offer insights about the patterns in vegetation dynamics. Both are useful sources of information for analyzing and monitoring ecosystem responses to environmental variations caused by natural and anthropogenic drivers. In the semi-arid region of Chile, climate variability and recent severe droughts in addition to land-use changes pose threats to the stability of local ecosystems. Normalized difference vegetation index time series (2000-2013) data from the moderate resolution imaging spectroradiometer (MODIS) was processed to monitor the trends and patterns of vegetation productivity and phenology observed over the last decade. An analysis of the relationship between (i) vegetation productivity and (ii) precipitation and temperature data for representative natural land-use cover classes was made. Using these data and ground measurements, productivity estimates were projected for two climate change scenarios (RCP2.6 and RCP8.5) at two altitudinal levels. Results showed negative trends of vegetation productivity below 2000 m a.s.l. and positive trends for higher elevations. Phenology analysis suggested that mountainous ecosystems were starting their growing period earlier in the season, coinciding with a decreased productivity peak during the growing season. The coastal shrubland/grassland land cover class had a significant positive relation with rainfall and a significant negative relation with temperature, suggesting that these ecosystems are vulnerable to climate change. Future productivity projections indicate that under an RCP8.5 climate change scenario, productivity could decline by 12% in the period of 2060-2100, leading to a severe vegetation degradation at lower altitudes and in drier areas.

  16. A 150 year record of inter-annual climate variability and organic carbon burial in Santa Monica and Santa Barbara Basins

    SciTech Connect

    Hagadorn, J.W.; Stott, L.D.; Sinha, A.; Rincon, M. . Dept. of Geological Sciences); Schimmelmann, A. . Scripps Inst. of Oceanography)

    1992-01-01

    Stable isotopic measurements were conducted on total organic carbon (TOC) and fossil planktonic foraminifera in laminated sediments collected from Santa Monica and Santa Barbara Basins, California Borderland, in order to investigate relationships between climatic variability and organic carbon burial. These data currently provide biannual sample resolution back to 1750 AD. During the past 150 years, there has been a positive covariance between the carbon isotopic composition of fossil planktonic foraminifera and of TOC. Periods of increased delta C-13 of TOC and foraminifera correspond to higher organic carbon burial in Santa Monica and Santa Barbara Basins. When combined, these patterns are interpreted as variation in productivity within the basins. Isotopic variability in TOC and planktonic foraminifera is significantly higher prior to 1900 AD. Although spring sea surface temperatures were also significantly more variable during this period, the authors do not recognize a systematic relationship between temperature and organic carbon burial. Spectral analysis of isotopic compositions of fossil foraminifera calcite, TOC, organic carbon burial and lamination frequency in the sediments reveal distinct spectral peaks at 5 and 7.7 years, corresponding to ENSO/El Nino frequencies. Additional spectral peaks occur at 19 and 20 years. Previous time series analyses of tree ring width records indicate similar decadal-scale frequencies and suggest a possible link to solar and/or lunar nodal tidal cycles. While these initial results suggest a relationship between climate-cyclicity, primary productivity and organic carbon burial, the phase relationship cannot be deciphered from this preliminary data set.

  17. Information transfer across the scales of climate variability: The effect of the 7-8 year cycle on the annual and interannual scales

    NASA Astrophysics Data System (ADS)

    Palus, Milan; Jajcay, Nikola; Hlinka, Jaroslav; Kravtsov, Sergey; Tsonis, Anastasios

    2016-04-01

    Complexity of the climate system stems not only from the fact that it is variable over a huge range of spatial and temporal scales, but also from the nonlinear character of the climate system that leads to interactions of dynamics across scales. The dynamical processes on large time scales influence variability on shorter time scales. This nonlinear phenomenon of cross-scale causal interactions can be observed due to the recently introduced methodology [1] which starts with a wavelet decomposition of a multi-scale signal into quasi-oscillatory modes of a limited bandwidth, described using their instantaneous phases and amplitudes. Then their statistical associations are tested in order to search for interactions across time scales. An information-theoretic formulation of the generalized, nonlinear Granger causality [2] uncovers causal influence and information transfer from large-scale modes of climate variability with characteristic time scales from years to almost a decade to regional temperature variability on short time scales. In analyses of air temperature records from various European locations, a quasioscillatory phenomenon with the period around 7-8 years has been identified as the factor influencing variability of surface air temperature (SAT) on shorter time scales. Its influence on the amplitude of the SAT annual cycle was estimated in the range 0.7-1.4 °C and the effect on the overall variability of the SAT anomalies (SATA) leads to the changes 1.5-1.7 °C in the annual SATA means. The strongest effect of the 7-8 year cycle was observed in the winter SATA means where it reaches 4-5 °C in central European station and reanalysis data [3]. This study is supported by the Ministry of Education, Youth and Sports of the Czech Republic within the Program KONTAKT II, Project No. LH14001. [1] M. Palus, Phys. Rev. Lett. 112 078702 (2014) [2] M. Palus, M. Vejmelka, Phys. Rev. E 75, 056211 (2007) [3] N. Jajcay, J. Hlinka, S. Kravtsov, A. A. Tsonis, M. Palus, Time

  18. Interannual and seasonal dynamics, and the age, of nonstructural carbohydrate pools in the stemwood of temperate trees across a climatic gradient in the Northeastern US

    NASA Astrophysics Data System (ADS)

    Richardson, A. D.; Carbone, M. S.; Czimczik, C. I.; Keenan, T. F.; Schaberg, P.; Murakami, P.; Xu, X.

    2012-04-01

    Like all plants, forest trees accumulate and store non-structural carbohydrates (NSC) as resources to be used in the future. This can be viewed as a bet-hedging strategy, providing reserves that the tree can draw on in times of stress—e.g., following disturbance, disease, or extreme climatic events. In the context of climate change, understanding factors influencing the availability of these stored NSC compounds to support growth and metabolism is essential for predicting the resilience of forests to environmental stress factors. We conducted this study to investigate the role of these stored NSC pools in the context of ecosystem C balance at time scales from days to years. At quarterly intervals over a three-year period, we monitored stemwood total NSC concentrations of the dominant tree species of New England. Work was conducted at three sites along a climatic gradient: an oak-dominated transition hardwood forest (Harvard Forest), a maple-beech-birch northern hardwood forest (Bartlett Experimental Forest), and a spruce-fir forest (Howland Forest). We observed large differences among species both in NSC concentrations, and in how the NSC pool is partitioned to different compounds (starch, sucrose, glucose, fructose, raffinose, and stachyose). Within a species, however, seasonal dynamics were remarkably similar across sites. We used the bomb radiocarbon (14C) spike to estimate the average age of the sugars and starches in the NSC pool in a subset of nine maple trees from each site. We found that the age of sugars ranged from 1-24 y and starches from 1-31 y. The ages of sugar and starch pools were highly correlated across all sites, and there was no significant difference in the mean age of the two pools, which was ~11 y. Using a one-pool representation of NSC reserves (similar to the standard approach used in several existing forest C models) our model FöBAAR (FOrest Biomass, Allocation, Assimilation and Respiration) failed to reproduce the seasonal NSC dynamics

  19. Interannual variability of photosynthesis across Africa and its attribution

    NASA Astrophysics Data System (ADS)

    Williams, Christopher A.; Hanan, Niall P.; Baker, Ian; Collatz, G. James; Berry, Joseph; Denning, A. Scott

    2008-12-01

    Africa is thought to be a large source of interannual variability in the global carbon cycle, only vaguely attributed to climate fluctuations. This study uses a biophysical model, Simple Biosphere, to examine in detail what specific factors, physiological (acute stress from low soil water, temperature, or low humidity) and biophysical (low vegetation radiation use), are responsible for spatiotemporal patterns of photosynthesis across the African continent during the period 1982-2003. Acute soil water stress emerges as the primary factor driving interannual variability of photosynthesis for most of Africa. Southern savannas and woodlands are a particular hot spot of interannual variability in photosynthesis, owing to high rainfall variability and photosynthetic potential but intermediate annual rainfall. Surprisingly low interannual variability of photosynthesis in much of the Sudano-Sahelian zone derives from relatively low vegetation cover, pronounced humidity stress, and somewhat lower rainfall variability, whereas perennially wet conditions diminish interannual variability in photosynthesis across much of the Congo Basin and coastal West Africa. Though not of focus here, the coefficient of variation in photosynthesis is notably high in drylands and desert margins (i.e., Sahel, Greater Horn, Namib, and Kalahari) having implications for supply of food and fiber. These findings emphasize that when considering impacts of climate change and land surface feedbacks to the atmosphere, it is important to recognize how vegetation, climate, and soil characteristics may conspire to filter or dampen ecosystem responses to hydroclimatic variability.

  20. Grape harvest and yield responses to inter-annual changes in temperature and precipitation in an area of north-east Spain with a Mediterranean climate.

    PubMed

    Camps, Josep Odó; Ramos, María Concepción

    2012-09-01

    This study presents an analysis of temperature and precipitation trends and their impact on grape harvests in the Penedès region (NE Spain). It includes analyses of maximum, minimum and mean daily temperatures (for both the growing and ripening seasons) and daily rainfall (for the hydrological year, the growing season and each phenological stage) for three observatories in the immediate area. We analysed a series of factors: beginning and end harvest dates; the day on which a given potential alcoholic degree was reached; and yield for several varieties of grape grown in the area in relation to climatic variables. Maximum temperatures increased at all the observatories, with greater values being recorded in recent years (1996-2009) than in previous decades (1960s-2000s): we observed increases in average growing season temperatures of 0.11°C per year for the period 1996-2009 vs 0.04°C per year for the period 1960-2009 at Vilafranca del Penedès. These temperature changes were due mainly to increases in maximum temperatures and an increase in the incidence of extreme heat (number of days with T > 30°C). Crop evapotranspiration also increased significantly during the same period. The Winkler index also increased, so the study area would correspond to region IV according to that climatic classification. There were no significant trends in annual rainfall but rainfall recorded between bloom and veraison decreased significantly at the three observatories, with the greatest decrease corresponding to the period 1996-2009. The dates on which harvests started and ended showed a continuous advance (of between -0.7 and -1.1 days per year, depending on the variety), which was significantly correlated with the average mean and maximum daily growing season temperatures (up to -7.68 days for 1°C increase). Winegrape yield was influenced by the estimated water deficit (crop evapotranspiration minus precipitation) in the bloom-veraison period; this value increased due to a

  1. Grape harvest and yield responses to inter-annual changes in temperature and precipitation in an area of north-east Spain with a Mediterranean climate

    NASA Astrophysics Data System (ADS)

    Camps, Josep Odó; Ramos, María Concepción

    2012-09-01

    This study presents an analysis of temperature and precipitation trends and their impact on grape harvests in the Penedès region (NE Spain). It includes analyses of maximum, minimum and mean daily temperatures (for both the growing and ripening seasons) and daily rainfall (for the hydrological year, the growing season and each phenological stage) for three observatories in the immediate area. We analysed a series of factors: beginning and end harvest dates; the day on which a given potential alcoholic degree was reached; and yield for several varieties of grape grown in the area in relation to climatic variables. Maximum temperatures increased at all the observatories, with greater values being recorded in recent years (1996-2009) than in previous decades (1960s-2000s): we observed increases in average growing season temperatures of 0.11°C per year for the period 1996-2009 vs 0.04°C per year for the period 1960-2009 at Vilafranca del Penedès. These temperature changes were due mainly to increases in maximum temperatures and an increase in the incidence of extreme heat (number of days with T > 30°C). Crop evapotranspiration also increased significantly during the same period. The Winkler index also increased, so the study area would correspond to region IV according to that climatic classification. There were no significant trends in annual rainfall but rainfall recorded between bloom and veraison decreased significantly at the three observatories, with the greatest decrease corresponding to the period 1996-2009. The dates on which harvests started and ended showed a continuous advance (of between -0.7 and -1.1 days per year, depending on the variety), which was significantly correlated with the average mean and maximum daily growing season temperatures (up to -7.68 days for 1°C increase). Winegrape yield was influenced by the estimated water deficit (crop evapotranspiration minus precipitation) in the bloom-veraison period; this value increased due to a

  2. Interannual variability of the South Indian Countercurrent

    NASA Astrophysics Data System (ADS)

    Menezes, Viviane V.; Phillips, Helen E.; Vianna, Marcio L.; Bindoff, Nathaniel L.

    2016-05-01

    In the present work, we investigate the interannual variability of the South Indian Countercurrent (SICC), a major and still understudied current of the Indian Ocean circulation. To characterize the interannual variability of the SICC, four different data sets (altimetry, GLORYS, OFAM3, and SODA) are analyzed using multiple tools, which include Singular Spectrum Analysis and wavelet methods. The quasi-biennial band dominates the SICC low-frequency variance, with the main peak in the 1.5-1.8 year interval. A secondary peak (2.1-2.5 year) is only found in the western basin. Interannual and decadal-type modulations of the quasi-biennial signal are also identified. In addition, limitations of SODA before the 1960s in the SICC region are revealed. Within the quasi-biennial band, the SICC system presents two main patterns with a multiple jet structure. One pattern is characterized by a robust northern jet, while in the other the central jet is well developed and northern jet is weaker. In both patterns, the southern jet has always a strong signature. When the northern SICC jet is stronger, the northern cell of the subtropical gyre has a triangular shape, with its southern limb having a strong equatorward slant. The quasi-biennial variability of the SICC is probably related to the Indian Ocean tropical climate modes that are known to have a strong biennial characteristic.

  3. Comparison of different wind products and buoy wind data with seasonality and interannual climate variability in the southern Bay of Biscay (2000-2009)

    NASA Astrophysics Data System (ADS)

    Alvarez, Inés; Gomez-Gesteira, Moncho; deCastro, Maite; Carvalho, David

    2014-08-01

    Ocean surface winds are essential factors in determining oceanographic and atmospheric processes that can affect ocean circulation and wave generation. Accurate surface wind datasets are needed, therefore, to enable the proper analysis of these processes. Wind data from six databases (National Centers for Environmental Prediction reanalysis (NCEP Reanalysis II), European Centre for Medium-Range Weather Forecasts (ECMWF) re-analysis (ERA-Interim), Modern-Era Retrospective-analysis for Research and Applications (MERRA), NCEP Climate Forecast System Reanalysis (CFSR), QuikSCAT and Cross-Calibrated Multi-Platform (CCMP)) were compared with wind measured in situ by four ocean buoys at the southern limit of the Bay of Biscay. The study covered the period 2000-2009 in such a way that the extent of the time series reduced the margin of error and allowed the disaggregation of the wind data using velocity bins and direction sectors. Statistical results confirmed that datasets with finer spatial resolution (lower than 0.5°×0.5°) gave better results, especially in near-shore areas. A more complete analysis was, therefore, carried out using the finer resolution datasets (QuikSCAT, CCMP and CFSR). This comparison showed that all the datasets were less accurate at low wind speeds (<4 m s-1) and more accurate at moderate wind speeds. The calculated mean wind speed errors were similar for the three datasets, and the lowest value (1.67 m s-1) was from the CCMP dataset. The lowest mean error for wind direction (~37°) was also observed in the CCMP data. The lowest mean wind speed (and direction) bias was obtained from the QuikSCAT data, and the next lowest from the CFSR data. The seasonality for north and east wind components was also determined for the last decade and the results were consistent with forcing for the continental slope current seasonality and winter temperatures or Navidad by wind stress. Correlations between NAO and north and east wind components were low showing

  4. Intra- and inter-annual uranium concentration variability in a Belizean stalagmite controlled by prior aragonite precipitation: A new tool for reconstructing hydro-climate using aragonitic speleothems

    NASA Astrophysics Data System (ADS)

    Jamieson, Robert A.; Baldini, James U. L.; Brett, Marianne J.; Taylor, Jessica; Ridley, Harriet E.; Ottley, Chris J.; Prufer, Keith M.; Wassenburg, Jasper A.; Scholz, Denis; Breitenbach, Sebastian F. M.

    2016-10-01

    Aragonitic speleothems are increasingly utilised as palaeoclimate archives due to their amenability to high precision U-Th dating. Proxy records from fast-growing aragonitic stalagmites, precisely dated to annual timescales, can allow investigation of climatic events occurring on annual or even sub-annual timescales with minimal chronological uncertainty. However, the behaviour of many trace elements, such as uranium, in aragonitic speleothems has not thus far been as well constrained as in calcitic speleothems. Here, we use uranium concentration shifts measured across primary calcite-to-aragonite mineralogical transitions in speleothems to calculate the distribution coefficient of uranium in aragonitic speleothems (derived DU = 3.74 ± 1.13). Because our calculated DU is considerably above 1 increased prior aragonite precipitation due to increased karst water residence time should strongly control stalagmite aragonite U/Ca values. Consequently, uranium concentrations in aragonitic speleothems should act as excellent proxies for effective rainfall. We test this using a high-resolution ICP-MS derived trace element dataset from a Belizean stalagmite. YOK-G is an aragonitic stalagmite from Yok Balum cave in Belize with an extremely robust monthly-resolved chronology built using annual δ13C cycles. We interpret seasonal U/Ca variations in YOK-G as reflecting changes in the amount and seasonality of prior aragonite precipitation driven by variable rainfall amounts. The U/Ca record strongly suggests that modern drying has occurred in Belize, and that this drying was primarily caused by a reduction in wet season rainfall. This is consistent with published stable isotope data from YOK-G also very strongly suggesting modern rainfall reductions, previously interpreted as the result of southward ITCZ displacement. Our results strongly suggest that U/Ca values in aragonitic speleothems are excellent proxies for rainfall variability. This new tool, combined with the

  5. The relationship between interannual and long-term cloud feedbacks

    DOE PAGES

    Zhou, Chen; Zelinka, Mark D.; Dessler, Andrew E.; ...

    2015-12-11

    The analyses of Coupled Model Intercomparison Project phase 5 simulations suggest that climate models with more positive cloud feedback in response to interannual climate fluctuations also have more positive cloud feedback in response to long-term global warming. Ensemble mean vertical profiles of cloud change in response to interannual and long-term surface warming are similar, and the ensemble mean cloud feedback is positive on both timescales. However, the average long-term cloud feedback is smaller than the interannual cloud feedback, likely due to differences in surface warming pattern on the two timescales. Low cloud cover (LCC) change in response to interannual andmore » long-term global surface warming is found to be well correlated across models and explains over half of the covariance between interannual and long-term cloud feedback. In conclusion, the intermodel correlation of LCC across timescales likely results from model-specific sensitivities of LCC to sea surface warming.« less

  6. 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

  7. Anatomy of the recurrent coastal sediment plume in Lake Michigan and its impacts on light climate, nutrients, and plankton

    NASA Astrophysics Data System (ADS)

    Vanderploeg, H. A.; Johengen, T. H.; Lavrentyev, P. J.; Chen, C.; Lang, G. A.; Agy, M. A.; Bundy, M. H.; Cavaletto, J. F.; Eadie, B. J.; Liebig, J. R.; Miller, G. S.; Ruberg, S. A.; McCormick, M. J.

    2007-03-01

    As part of the Episodic Events Great Lakes Experiment, we sampled total suspended matter (TSM), light climate, nutrients, and plankton along cross-margin transects in southern Lake Michigan during February, March, and April 1998-2000 to capture conditions before, during, and after the occurrence of storm-driven recurrent coastal sediment plumes to define the anatomy of the resuspension events and get insights into their interactions with nutrients and plankton. Variability in timing and strength of winter storms among years led to different timing, intensity, and extent of plumes among years. TSM concentrations in the core of plumes varied between 15 and 30 mg L-1, and photic depth was reduced to ˜1 to 2 m, thus potentially seriously limiting phytoplankton growth in plume areas. Total P concentration was highly correlated with TSM and river influence. Chlorophyll concentrations were lower in plume regions than in adjacent areas, in contrast to the relatively constant chlorophyll concentration across the plume predicted by a coupled hydrodynamic and nutrient-phytoplankton-zooplankton model. Contrary to expectation, protozoan microzooplankton (MZ) biomass was not more abundant in the plume than adjacent waters, but was highest in nearshore areas receiving river inflow. Storms affected horizontal distribution of zooplankton. Because of the lower concentrations of phytoplankton in the plume, the plume over the short term had a negative impact on zooplankton during this food-limiting season. Our results combined with those of other EEGLE studies lead us to conclude that storms and storm-driven plumes had a negative effect on the planktonic food web.

  8. Validation of Interannual Differences of AIRS Monthly Mean Parameters

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Iredell, Lena; Keita, Fricky; Molnar, Gyula

    2005-01-01

    Monthly mean fields of select geophysical parameters derived from analysis of AIRS/AMSU data, and their interannual differences, are shown and compared with analogous fields derived from other sources. All AIRS fields are derived using the AIRS Science Team Version 4 algorithm. Monthly mean results are shown for January 2004, as are interannual differences between January 2004 and January 2003. AIRS temperature and water vapor profile fields are compared with monthly mean collocated ECMWF 3 hour forecast and monthly mean TOVS Pathfinder Path A data. AIRS Tropospheric and Stratospheric coarse climate indicators are compared with analogous MSU products derived by Spencer and christy and found in the TOVS Pathfinder Path A data set. Total ozone is compared with results produced by TOMS. OLR is compared with OLR derived using CERES data and found in the TOVS Pathfinder Path A data set. AIRS results agree well in all cases, especially in the interannual difference sense.

  9. Clusters of interannual sea ice variability in the northern hemisphere

    NASA Astrophysics Data System (ADS)

    Fučkar, Neven S.; Guemas, Virginie; Johnson, Nathaniel C.; Massonnet, François; Doblas-Reyes, Francisco J.

    2016-09-01

    We determine robust modes of the northern hemisphere (NH) sea ice variability on interannual timescales disentangled from the long-term climate change. This study focuses on sea ice thickness (SIT), reconstructed with an ocean-sea-ice general circulation model, because SIT has a potential to contain most of the interannual memory and predictability of the NH sea ice system. We use the K-means cluster analysis—one of clustering methods that partition data into groups or clusters based on their distances in the physical space without the typical constraints of other unsupervised learning statistical methods such as the widely-used principal component analysis. To adequately filter out climate change signal in the Arctic from 1958 to 2013 we have to approximate it with a 2nd degree polynomial. Using 2nd degree residuals of SIT leads to robust K-means cluster patterns, i.e. invariant to further increase of the polynomial degree. A set of clustering validity indices yields K = 3 as the optimal number of SIT clusters for all considered months and seasons with strong similarities in their cluster patterns. The associated time series of cluster occurrences exhibit predominant interannual persistence with mean timescale of about 2 years. Compositing analysis of the NH surface climate conditions associated with each cluster indicates that wind forcing seem to be the key factor driving the formation of interannual SIT cluster patterns during the winter. Climate memory in SIT with such interannual persistence could lead to increased predictability of the Artic sea ice cover beyond seasonal timescales.

  10. Recurrent recurrent gallstone ileus.

    PubMed

    Hussain, Z; Ahmed, M S; Alexander, D J; Miller, G V; Chintapatla, S

    2010-07-01

    We describe the second reported case of three consecutive episodes of gallstone ileus and ask the question whether recurrent gallstone ileus justifies definitive surgery to the fistula itself or can be safely managed by repeated enterotomies.

  11. Terrestrial Waters and Sea Level Variations on Interannual Time Scale

    NASA Technical Reports Server (NTRS)

    Llovel, W.; Becker, M.; Cazenave, A.; Jevrejeva, S.; Alkama, R.; Decharme, B.; Douville, H.; Ablain, M.; Beckley, B.

    2011-01-01

    On decadal to multi-decadal time scales, thermal expansion of sea waters and land ice loss are the main contributors to sea level variations. However, modification of the terrestrial water cycle due to climate variability and direct anthropogenic forcing may also affect sea level. For the past decades, variations in land water storage and corresponding effects on sea level cannot be directly estimated from observations because these are almost non-existent at global continental scale. However, global hydrological models developed for atmospheric and climatic studies can be used for estimating total water storage. For the recent years (since mid-2002), terrestrial water storage change can be directly estimated from observations of the GRACE space gravimetry mission. In this study, we analyse the interannual variability of total land water storage, and investigate its contribution to mean sea level variability at interannual time scale. We consider three different periods that, each, depend on data availability: (1) GRACE era (2003-2009), (2) 1993-2003 and (3) 1955-1995. For the GRACE era (period 1), change in land water storage is estimated using different GRACE products over the 33 largest river basins worldwide. For periods 2 and 3, we use outputs from the ISBA-TRIP (Interactions between Soil, Biosphere, and Atmosphere-Total Runoff Integrating Pathways) global hydrological model. For each time span, we compare change in land water storage (expressed in sea level equivalent) to observed mean sea level, either from satellite altimetry (periods 1 and 2) or tide gauge records (period 3). For each data set and each time span, a trend has been removed as we focus on the interannual variability. We show that whatever the period considered, interannual variability of the mean sea level is essentially explained by interannual fluctuations in land water storage, with the largest contributions arising from tropical river basins.

  12. Interannual rainfall variability and SOM-based circulation classification

    NASA Astrophysics Data System (ADS)

    Wolski, Piotr; Jack, Christopher; Tadross, Mark; van Aardenne, Lisa; Lennard, Christopher

    2017-03-01

    Self-Organizing Maps (SOM) based classifications of synoptic circulation patterns are increasingly being used to interpret large-scale drivers of local climate variability, and as part of statistical downscaling methodologies. These applications rely on a basic premise of synoptic climatology, i.e. that local weather is conditioned by the large-scale circulation. While it is clear that this relationship holds in principle, the implications of its implementation through SOM-based classification, particularly at interannual and longer time scales, are not well recognized. Here we use a SOM to understand the interannual synoptic drivers of climate variability at two locations in the winter and summer rainfall regimes of South Africa. We quantify the portion of variance in seasonal rainfall totals that is explained by year to year differences in the synoptic circulation, as schematized by a SOM. We furthermore test how different spatial domain sizes and synoptic variables affect the ability of the SOM to capture the dominant synoptic drivers of interannual rainfall variability. Additionally, we identify systematic synoptic forcing that is not captured by the SOM classification. The results indicate that the frequency of synoptic states, as schematized by a relatively disaggregated SOM (7 × 9) of prognostic atmospheric variables, including specific humidity, air temperature and geostrophic winds, captures only 20-45% of interannual local rainfall variability, and that the residual variance contains a strong systematic component. Utilising a multivariate linear regression framework demonstrates that this residual variance can largely be explained using synoptic variables over a particular location; even though they are used in the development of the SOM their influence, however, diminishes with the size of the SOM spatial domain. The influence of the SOM domain size, the choice of SOM atmospheric variables and grid-point explanatory variables on the levels of explained

  13. Oceanic Control of Northeast Pacific Hurricane Activity at Interannual Timescales

    SciTech Connect

    Balaguru, Karthik; Leung, Lai-Yung R.; Yoon, Jin-Ho

    2013-10-16

    Despite the strong dependence of the Power Dissipation Index (PDI), which is a measure of the intensity of Tropical Cyclone (TC) activity, on tropical sea-surface temperatures (SSTs), the variations in PDI are not completely explained by SST. Here we show, using an analysis of a string of observational data sets, that the variability of the thermocline depth (TD) in the east Pacific exerts a significant degree of control on the variability of PDI in that region. On average, a deep thermocline with a larger reservoir of heat favors TC intensification by reducing SST cooling while a shallow thermocline with a smaller heat reservoir promotes enhanced SST cooling that contributes to TC decay. At interannual time scales, the variability of basin-mean TD accounts for nearly 30% of the variability in the PDI during the TC season. Also, about 20% of the interannual variability in the east Pacific basin-mean TD is due to the El Niño and the Southern Oscillation (ENSO), a dominant climate signal in this region. This study suggests that a better understanding of the factors governing the interannual variability of the TD conditions in the east Pacific and how they may change over time, may lead to an improved projection of future east Pacific TC activity.

  14. Decadal and interannual variability of the Indian Ocean SST

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, Lakshmi; Krishnamurthy, V.

    2016-01-01

    The variability of the Indian Ocean on interannual and decadal timescales is investigated in observations, coupled model simulation and model experiment. The Indian Ocean Dipole (IOD) mode was specifically analyzed using a data-adaptive method. This study reveals one decadal mode and two interannual modes in the sea surface temperature (SST) of the IOD. The decadal mode in the IOD is associated with the Pacific Decadal Oscillation (PDO) of the North Pacific SST. The two interannual modes are related to the biennial and canonical components of El Niño-Southern Oscillation (ENSO), consistent with previous studies. This study hypothesizes that the relation between the Indian Ocean and the North Pacific on decadal scale may be through the northerly winds from the western North Pacific. The long simulation of Community Climate System Model version 4 also indicates the presence of IOD modes associated with the decadal PDO and canonical ENSO modes. However, the model fails to simulate the biennial ENSO mode in the Indian Ocean. The relation between the Indian Ocean and North Pacific Ocean is further supported by the regionally de-coupled model experiment.

  15. Winter to winter recurrence of atmospheric circulation anomalies over East Asia and its impact on winter surface air temperature anomalies.

    PubMed

    Zhao, Xia; Yang, Guang

    2017-01-01

    The persistence of atmospheric circulation anomalies over East Asia shows a winter to winter recurrence (WTWR) phenomenon. Seasonal variations in sea level pressure anomalies and surface wind anomalies display significantly different characteristics between WTWR and non-WTWR years. The WTWR years are characterized by the recurrence of both a strong (weak) anomalous Siberian High and an East Asian winter monsoon over two successive winters without persistence through the intervening summer. However, anomalies during the non-WTWR years have the opposite sign between the current and ensuing winters. The WTWR of circulation anomalies contributes to that of surface air temperature anomalies (SATAs), which is useful information for improving seasonal and interannual climate predictions over East Asia and China. In the positive (negative) WTWR years, SATAs are cooler (warmer) over East Asia in two successive winters, but the signs of the SATAs are opposite in the preceding and subsequent winters during the non-WTWR years.

  16. Winter to winter recurrence of atmospheric circulation anomalies over East Asia and its impact on winter surface air temperature anomalies

    PubMed Central

    2017-01-01

    The persistence of atmospheric circulation anomalies over East Asia shows a winter to winter recurrence (WTWR) phenomenon. Seasonal variations in sea level pressure anomalies and surface wind anomalies display significantly different characteristics between WTWR and non-WTWR years. The WTWR years are characterized by the recurrence of both a strong (weak) anomalous Siberian High and an East Asian winter monsoon over two successive winters without persistence through the intervening summer. However, anomalies during the non-WTWR years have the opposite sign between the current and ensuing winters. The WTWR of circulation anomalies contributes to that of surface air temperature anomalies (SATAs), which is useful information for improving seasonal and interannual climate predictions over East Asia and China. In the positive (negative) WTWR years, SATAs are cooler (warmer) over East Asia in two successive winters, but the signs of the SATAs are opposite in the preceding and subsequent winters during the non-WTWR years. PMID:28178351

  17. The interannual variability of polar cap recessions as a measure of Martian climate and weather: Using Earth-based data to augment the time line for the Mars observer mapping mission

    NASA Technical Reports Server (NTRS)

    Martin, L. J.; James, P. B.

    1992-01-01

    The recessions of the polar ice caps are the most visible and most studied indication of seasonal change on Mars. Circumstantial evidence links these recessions to the seasonal cycles of CO2, water, and dust. The possible advent of a planet encircling storm during the Mars Observer (MO) mission will provide a detailed correlation with a cap recession for that one Martian year. That cap recession will then be compared with other storm and nonstorm years. MO data will also provide a stronger link between cap recessions and the water and CO2 cycles. Cap recession variability might also be used to determine the variability of these cycles. After nearly a century of valiant attempts at measuring polar cap recessions, including Mariner 9 and Viking data, MO will provide the first comprehensive dataset. In contrast to MO, the older data are much less detailed and precise and could be forgotten, except that it will still be the only information on interannual variability. By obtaining simultaneous Earth-based observations (including those from Hubble) during the MO mission, direct comparisons can be made between the datasets.

  18. High resolution Greenland ice sheet inter-annual mass variations combining GRACE gravimetry and Envisat altimetry

    NASA Astrophysics Data System (ADS)

    Su, Xiaoli; Shum, C. K.; Guo, Junyi; Duan, Jianbin; Howat, Ian; Yi, Yuchan

    2015-07-01

    Inter-annual mass variations of the Greenland ice sheet (GrIS) are important for improving mass balance estimates, validation of atmospheric circulation models and their potential improvement. By combining observed inter-annual variations from Gravity Recovery and Climate Experiment (GRACE) and Environmental Satellite (Envisat) altimetry data over the period from January 2003 to December 2009, we are able to estimate the nominal density, with the objective of obtaining higher resolution mass changes using altimeter data at the inter-annual scale. We find high correlations between these two inter-annual variations on the order of 0.7 over 60% of the GrIS, in particular over the west side along the central ice divide. Significant negative correlations are found in parts of Northeast and Southeast GrIS, where negative inter-annual variation correlations were also found between mass change from GRACE and snow depth from ECMWF reanalysis in a previous study. In the regions of positive correlation, the estimated nominal densities range from 383.7 ± 50.9 to 596.2 ± 34.1 kgm-3. We demonstrate the feasibility of obtaining high-resolution inter-annual mass variation over Southwest GrIS, one of the regions with positive correlations, based on density-corrected Envisat altimetry, 2003-2009. A definitive explanation for the existence of regions of negative correlation remains elusive.

  19. Marine and terrestrial influences on interannual CO{sub 2} variations at Mauna Loa and the South Pole

    SciTech Connect

    Dettinger, M.D.; Ghil, M.

    1997-11-01

    Data are presented and very briefly discussed regarding interannual variations of atmospheric carbon dioxide (CO{sub 2}) concentrations. Interannual variations are isolated from monthly concentrations by using singular-spectrum analysis of CO{sub 2} and atmospheric carbon isotopic ratios at Mauna Loa, Hawaii, United States and at the South Pole. Interannual variations are shared at the two sites, and can be used to differentiate between marine and land-surface responses to different interannual climate variations on global scales. Two time-scales are compared: (1) quasi-quadrennial (QQ) and (2) 3-year. Phase relations indicate that QQ variations are dominated by terrestrial influences, whereas the 3-year variations reflect marine (upwelling) influences in the eastern Pacific. The contrasting CO{sub 2} responses on these two time scales thus provide a useful measure of differences in global climate responses, and especially in terrestrial-ecosystem responses to different tropical forcings. 1 fig.

  20. Soil moisture controls on inter-annual variability of biogenic isoprene emissions and ozone

    NASA Astrophysics Data System (ADS)

    Tawfik, A. B.; Shalaby, A.; Steiner, A. L.; Zakey, A.

    2010-12-01

    Biogenic isoprene emissions directly respond to leaf temperature, photosynthetic active radiation, and soil moisture. These climate variables can be important for estimating biogenic emissions and their impact on interannual variability of ground-level ozone and secondary organic aerosol. Due to the non-linear relationship between temperature and soil moisture, observational data alone are not capable of quantifying each variable’s contribution to isoprene emissions. A process-based emissions model (the Model of Emissions of Gases and Aerosols from Nature; MEGAN) is coupled to a regional climate and chemistry model (RegCM-CLM-CHEM) to assess the contributions of environmental variables controlling isoprene emissions on climatological time scales. A fully online simulation was performed from 1994-2008 where isoprene emissions respond at each land surface time step to all environmental variables. A first order Taylor expansion method was used to determine percent contribution to inter-annual isoprene variability from each environmental variable. In July, leaf temperature accounts for more than 65% of inter-annual variations in isoprene emissions over the Plains and the Great Lakes region. However, soil moisture variations tend to dominate controls on inter-annual variability for the southeastern U.S. (> 60%). Model simulations and observational data from the Photochemical Assessment Monitoring Stations (PAMS) are implemented to estimate the effects of drought on inter-annual variations of isoprene and ozone.

  1. Interannual Atmospheric Variability Simulated by a Mars GCM: Impacts on the Polar Regions

    NASA Technical Reports Server (NTRS)

    Bridger, Alison F. C.; Haberle, R. M.; Hollingsworth, J. L.

    2003-01-01

    It is often assumed that in the absence of year-to-year dust variations, Mars weather and climate are very repeatable, at least on decadal scales. Recent multi-annual simulations of a Mars GCM reveal however that significant interannual variations may occur with constant dust conditions. In particular, interannual variability (IAV) appears to be associated with the spectrum of atmospheric disturbances that arise due to baroclinic instability. One quantity that shows significant IAV is the poleward heat flux associated with these waves. These variations and their impacts on the polar heat balance will be examined here.

  2. North-South precipitation patterns in western North America on interannual-to-decadal timescales

    USGS Publications Warehouse

    Dettinger, M.D.; Cayan, D.R.; Diaz, Henry F.; Meko, D.M.

    1998-01-01

    The overall amount of precipitation deposited along the West Coast and western cordillera of North America from 25??to 55??N varies from year to year, and superimposed on this domain-average variability are varying north-south contrasts on timescales from at least interannual to interdecadal. In order to better understand the north-south precipitation contrasts, their interannual and decadal variations are studied in terms of how much they affect overall precipitation amounts and how they are related to large-scale climatic patterns. Spatial empirical orthogonal functions (EOFs) and spatial moments (domain average, central latitude, and latitudinal spread) of zonally averaged precipitation anomalies along the westernmost parts of North America are analyzed, and each is correlated with global sea level pressure (SLP) and sea surface temperature series, on interannual (defined here as 3-7 yr) and decadal (>7 yr) timescales. The interannual band considered here corresponds to timescales that are particularly strong in tropical climate variations and thus is expected to contain much precipitation variability that is related to El Nino-Southern Oscillation; the decadal scale is defined so as to capture the whole range of long-term climatic variations affecting western North America. Zonal EOFs of the interannual and decadal filtered versions of the zonal-precipitation series are remarkably similar. At both timescales, two leading EOFs describe 1) a north-south seesaw of precipitation pivoting near 40??N and 2) variations in precipitation near 40??N, respectively. The amount of overall precipitation variability is only about 10% of the mean and is largely determined by precipitation variations around 40??-45??N and most consistently influenced by nearby circulation patterns; in this sense, domain-average precipitation is closely related to the second EOF. The central latitude and latitudinal spread of precipitation distributions are strongly influenced by precipitation

  3. Interannual variability of monthly sea-ice distributions in the north polar region

    SciTech Connect

    Parkinson, C.L.

    1992-03-01

    Passive-microwave data from the Nimbus 5 and Nimbus 7 satellites have been used to determine and map, by month, the interannual variability of the spatial distribution of north polar sea ice over the period 1973-1987. Results are illustrated for the months of January and July, during the winter ice growth and summer ice decay seasons, respectively. In January, the greatest interannual variability in the distribution of the ice occurs in the Sea of Okhotsk, whereas the portions of the ice edge exhibiting the least interannual variability lie in the southern Greenland Sea and immediately to the southwest of Svalbard. In July, spatial variability is high in Hudson Bay, Baffin Bay, the southern Kara Sea, and the northern Barents Sea. The monthly maps are meant to allow ready comparison with past and future sea ice distributions and aid in the assessment of whether specific changes are climatically important.

  4. Seasonal, interannual and event scale variation in North Pacific ecosystems

    NASA Astrophysics Data System (ADS)

    Yoo, Sinjae; Batchelder, Harold P.; Peterson, William T.; Sydeman, William J.

    2008-05-01

    slightly lagged) with those of phytoplankton with a few exceptions. Exceptions occur in the Eastern Subarctic Gyre where annual peaks of chlorophyll occur in autumn, after the peak in zooplankton biomass. Interannual variation of annually averaged chlorophyll in 30 regions show three patterns, one positively related to El Niño, one negatively related to El Niño, and one with longer-scale variation, possibly related to climate regimes. Nine regions did not match any of the three patterns. Interannual variation in zooplankton abundance/biomass from selected regions indicates that El Niño may be the major source of interannual variability with its effects modulated by longer-scale variation, such as by the Pacific Decadal Oscillation. Two well-documented environmental events in the Northern California Current, in 2002 and 2005, exemplify how short-term disruption in atmospheric forcing causes changes in ocean hydrography and circulation that has significant impacts on primary production and ripple effects throughout multiple trophic levels of the ecosystem. We conclude that a closer look at the data often yields interesting results that might not necessarily be gained by considering the broad generalizations. Specifically, we observe that short-term disruptions of the ecosystem at the primary producer level may impact higher trophic levels in nonlinear ways that lead to unpredic impacts when one considers the entire food chain.

  5. Interannual variability of tropospheric trace gases and aerosols: The role of biomass burning emissions

    NASA Astrophysics Data System (ADS)

    Voulgarakis, Apostolos; Marlier, Miriam E.; Faluvegi, Greg; Shindell, Drew T.; Tsigaridis, Kostas; Mangeon, Stéphane

    2015-07-01

    Fires are responsible for a range of gaseous and aerosol emissions. However, their influence on the interannual variability of atmospheric trace gases and aerosols has not been systematically investigated from a global perspective. We examine biomass burning emissions as a driver of interannual variability of large-scale abundances of short-lived constituents such as carbon monoxide (CO), hydroxyl radicals (OH), ozone, and aerosols using the Goddard Institute for Space Studies ModelE composition-climate model and a range of observations, with an emphasis on satellite information. Our model captures the observed variability of the constituents examined in most cases, but with substantial underestimates in boreal regions. The strongest interannual variability on a global scale is found for carbon monoxide (~10% for its global annual burden), while the lowest is found for tropospheric ozone (~1% for its global annual burden). Regionally, aerosol optical depth shows the largest variability which exceeds 50%. Areas of strong variability of both aerosols and CO include the tropical land regions (especially Equatorial Asia and South America) and northern high latitudes, while even regions in the northern midlatitudes experience substantial interannual variability of aerosols. Ozone variability peaks over equatorial Asia in boreal autumn, partly due to varying biomass burning emissions, and over the western and central Pacific in the rest of the year, mainly due to meteorological fluctuations. We find that biomass burning emissions are almost entirely responsible for global CO interannual variability, and similarly important for OH variability. The same is true for global and regional aerosol variability, especially when not taking into account dust and sea-salt particles. We show that important implications can arise from such interannual influences for regional climate and air quality.

  6. Seasonal and interannual variations of upper ocean heat balance off the west coast of Australia

    NASA Astrophysics Data System (ADS)

    Feng, Ming; Biastoch, Arne; BöNing, Claus; Caputi, Nick; Meyers, Gary

    2008-12-01

    The Leeuwin Current, a warm, poleward flowing eastern boundary current, dominates the surface circulation off the west coast of Australia and has profound influence on regional marine ecosystem and fisheries recruitment. In this study, the seasonal and interannual variations of upper ocean heat balance in the Leeuwin Current region are analyzed by using an eddy-resolving numerical model simulation, as a first step to quantify the climate impacts on regional ocean thermodynamics and marine ecosystem. The volume transport and heat advection of the Leeuwin Current are stronger during the austral winter on the seasonal cycle and are stronger during a La Nina event on the interannual scale. On both seasonal and interannual timescales, the mixed layer heat budget off the west coast of Australia is predominantly balanced between the variations of the Leeuwin Current heat advection and heat flux across the air-sea interface. On the interannual timescale, the variation of the Leeuwin Current heat advection tends to lead that of the air-sea (latent) heat flux by two months, which is likely a reflection of advection timescales of the Leeuwin Current and its eddy field. The interannual variation of the average February-April sea surface temperature off the west coast of Australia, which is crucial for the larval settlement of western rock lobster, is mostly influenced by the Leeuwin Current heat advection as well as the ocean memory from the previous austral winter, with the air-sea heat exchange playing a buffering role.

  7. Recurrent vulvovaginitis.

    PubMed

    Powell, Anna M; Nyirjesy, Paul

    2014-10-01

    Vulvovaginitis (VV) is one of the most commonly encountered problems by a gynecologist. Many women frequently self-treat with over-the-counter medications, and may present to their health-care provider after a treatment failure. Vulvovaginal candidiasis, bacterial vaginosis, and trichomoniasis may occur as discreet or recurrent episodes, and have been associated with significant treatment cost and morbidity. We present an update on diagnostic capabilities and treatment modalities that address recurrent and refractory episodes of VV.

  8. Meningioma recurrence

    PubMed Central

    Bencze, János; Varkoly, Gréta; Kouhsari, Mahan C; Klekner, Álmos

    2016-01-01

    Abstract Meningioma accounts for more than 30% of all intracranial tumours. It affects mainly the elderly above the age of 60, at a female:male ratio of 3:2. The prognosis is variable: it is usually favourable with no progression in tumour grade and no recurrence in WHO grade 1 tumours. However, a minority of tumours represent atypical (grade 2) or anaplastic (grade 3) meningiomas; this heterogeneity is also reflected in histopathological appearances. Irrespective of the grade, the size of the tumour and the localisation may have severe, sometimes lethal consequences. Following neurosurgical interventions to remove the tumour, recurrence and progression in WHO grade may occur. Our knowledge on predisposing histomorphological and molecular factors of recurrence is rather limited. These can be classified as I) demographic II) environmental, III) genetic and epigenetic IV) imaging, V) neuropathological, and VI) neurosurgical. In view of the complex background of tumour recurrence, the recognition of often subtle signs of increased risk of recurrence requires close collaboration of experts from several medical specialties. This multidisciplinary approach results in better therapy and fewer complications related to tumour recurrence. PMID:28352788

  9. ENSO Modulations by Interannual Variability of Freshwater Forcing and Ocean Biology-induced Heating feedbacks in the Tropical Pacific

    NASA Astrophysics Data System (ADS)

    Zhang, R. H.

    2015-12-01

    Recent studies have identified clear climate feedbacks associated with interannual variations in freshwater forcing (FWF) and ocean biology-induced heating (OBH) in the tropical Pacific. The interrelationships among the related anomaly fields are analyzed using hybrid coupled model (HCM) simulations to illustrate their combined roles in modulating the El Niño-Southern Oscillation (ENSO). The HCM-based supporting experiments are performed to isolate the related feedbacks, with interannually varying FWF and OBH being represented individually or collectively, which allows their effects to be examined in a clear way. It is demonstrated that the interannual freshwater forcing enhances ENSO variability and slightly prolongs the simulated ENSO period, while the interannual OBH reduces ENSO variability and slightly shortens the ENSO period, with their feedback effects tending to counteract each other.

  10. ENSO Modulations due to Interannual Variability of Freshwater Forcing and Ocean Biology-induced Heating in the Tropical Pacific

    NASA Astrophysics Data System (ADS)

    Zhang, Rong-Hua; Gao, Chuan; Kang, Xianbiao; Zhi, Hai; Wang, Zhanggui; Feng, Licheng

    2015-12-01

    Recent studies have identified clear climate feedbacks associated with interannual variations in freshwater forcing (FWF) and ocean biology-induced heating (OBH) in the tropical Pacific. The interrelationships among the related anomaly fields are analyzed using hybrid coupled model (HCM) simulations to illustrate their combined roles in modulating the El Niño-Southern Oscillation (ENSO). The HCM-based supporting experiments are performed to isolate the related feedbacks, with interannually varying FWF and OBH being represented individually or collectively, which allows their effects to be examined in a clear way. It is demonstrated that the interannual freshwater forcing enhances ENSO variability and slightly prolongs the simulated ENSO period, while the interannual OBH reduces ENSO variability and slightly shortens the ENSO period, with their feedback effects tending to counteract each other.

  11. ENSO Modulations due to Interannual Variability of Freshwater Forcing and Ocean Biology-induced Heating in the Tropical Pacific.

    PubMed

    Zhang, Rong-Hua; Gao, Chuan; Kang, Xianbiao; Zhi, Hai; Wang, Zhanggui; Feng, Licheng

    2015-12-18

    Recent studies have identified clear climate feedbacks associated with interannual variations in freshwater forcing (FWF) and ocean biology-induced heating (OBH) in the tropical Pacific. The interrelationships among the related anomaly fields are analyzed using hybrid coupled model (HCM) simulations to illustrate their combined roles in modulating the El Niño-Southern Oscillation (ENSO). The HCM-based supporting experiments are performed to isolate the related feedbacks, with interannually varying FWF and OBH being represented individually or collectively, which allows their effects to be examined in a clear way. It is demonstrated that the interannual freshwater forcing enhances ENSO variability and slightly prolongs the simulated ENSO period, while the interannual OBH reduces ENSO variability and slightly shortens the ENSO period, with their feedback effects tending to counteract each other.

  12. Interannual variability of Winter Precipitation in Southeast China

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Fraedrich, Klaus; zhu, Xiuhua; Sielmann, Frank

    2014-05-01

    The observed winter (DJF) precipitation in Southeast China (1961-2010) is characterized by a monopole pattern of the three-monthly Standardized Precipitation Index (SPI-3) whose interannual variability is related to the anomalies of East Asian Winter Monsoon (EAWM) systems. Dynamic composites and linear regression analysis indicate that the intensity of EAWM and Siberia High (SH), the position of East Asian Trough (EAT), El Niño events and SST anomalies over South China Sea (SCS) influence different regions of anomalous Southeast China winter precipitation on interannual scales. The circulation indices (EAWM, SH and EAT) mainly affect the winter precipitation in the eastern part of Southeast China. El Niño events affect the South China winter precipitation due to the anticyclone anomalies over Philippines. The effect of SCS SST anomalies on the winter precipitation is mainly in the south part of Yangtze River. And the contributions from all the impact factors do not counteract with one another to generate the Southeast China winter precipitation variability. Thus, a set of circulation regimes, represented by a handful indices, provide the basis for modeling precipitation anomalies or extremes in future climate projections.

  13. Interannual variability of deep convection in the Northwestern Mediterranean simulated with a coupled AORCM

    NASA Astrophysics Data System (ADS)

    L'Hévéder, Blandine; Li, Laurent; Sevault, Florence; Somot, Samuel

    2013-08-01

    A hindcast experiment of the Mediterranean present-day climate is performed using a fully-coupled Atmosphere-Ocean Regional Climate Model (AORCM) for the Mediterranean basin. The new model, called LMDz-NEMO-Med, is composed of LMDz4-regional as atmospheric component and of NEMOMED8 as oceanic component. This AORCM equilibrates freely, without any flux adjustment, neither in fresh water nor in heat. At its atmospheric lateral boundary conditions, it is driven by ERA-40 data from 1958 to 2001, after a spin-up of 40 years in coupled configuration. The model performance is assessed and compared with available observational datasets. The model skill in reproducing mean state and inter-annual variability of main atmospheric and oceanic surface fields is in line with that of state-of-the-art AORCMs. Considering the ocean behaviour, the inter-annual variations of the basin-scale heat content are in very good agreement with the observations. The model results concerning salt content could not be adequately validated. High inter-annual variability of deep convection in the Gulf of Lion is simulated, with 53 % of convective winters, representative of the present climate state. The role of different factors influencing the deep convection and its inter-annual variability is examined, including dynamic and hydrostatic ocean preconditioning and atmospheric surface forcing. A conceptual framework is outlined and validated in linking the occurrence of deep convection to the efficiency of the integrated surface buoyancy fluxes along the winter season to mix the initially stratified averaged water column down to the convective threshold depth. This simple framework (based only on 2 independent variables) is able to explain 60 % (resp. 69 %) of inter-annual variability of the deep water formation rate (resp. maximum mixed layer depth) for the West Mediterranean Deep Water (WMDW) formation process.

  14. What is the Effect of Interannual Hydroclimatic Variability on Water Supply Reservoir Operations?

    NASA Astrophysics Data System (ADS)

    Galelli, S.; Turner, S. W. D.

    2015-12-01

    Rather than deriving from a single distribution and uniform persistence structure, hydroclimatic data exhibit significant trends and shifts in their mean, variance, and lagged correlation through time. Consequentially, observed and reconstructed streamflow records are often characterized by features of interannual variability, including long-term persistence and prolonged droughts. This study examines the effect of these features on the operating performance of water supply reservoirs. We develop a Stochastic Dynamic Programming (SDP) model that can incorporate a regime-shifting climate variable. We then compare the performance of operating policies—designed with and without climate variable—to quantify the contribution of interannual variability to standard policy sub-optimality. The approach uses a discrete-time Markov chain to partition the reservoir inflow time series into small number of 'hidden' climate states. Each state defines a distinct set of inflow transition probability matrices, which are used by the SDP model to condition the release decisions on the reservoir storage, current-period inflow and hidden climate state. The experimental analysis is carried out on 99 hypothetical water supply reservoirs fed from pristine catchments in Australia—all impacted by the Millennium drought. Results show that interannual hydroclimatic variability is a major cause of sub-optimal hedging decisions. The practical import is that conventional optimization methods may misguide operators, particularly in regions susceptible to multi-year droughts.

  15. Recurrent novae

    NASA Technical Reports Server (NTRS)

    Hack, Margherita; Selvelli, Pierluigi

    1993-01-01

    Recurrent novae seem to be a rather inhomogeneous group: T CrB is a binary with a M III companion; U Sco probably has a late dwarf as companion. Three are fast novae; two are slow novae. Some of them appear to have normal chemical composition; others may present He and CNO excess. Some present a mass-loss that is lower by two orders of magnitude than classical novae. However, our sample is too small for saying whether there are several classes of recurrent novae, which may be related to the various classes of classical novae, or whether the low mass-loss is a general property of the class or just a peculiarity of one member of the larger class of classical novae and recurrent novae.

  16. Interannual Variability of Ozone and Ultraviolet Exposure

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Piacentini, R. D.; Ziemke, J.; Celarier, E.; Larko. D.

    1999-01-01

    Annual zonal averages of ozone amounts from Nimbus-7/TOMS (Total Ozone Mapping Spectrometer) (1979 to 1992) are used to estimate the interannual variability of ozone and UVB (290 - 315 nm) irradiance between plus or minus 60 deg. latitude. Clear-sky interannual ozone and UVB changes are mainly caused by the Quasi Biennial Oscillation (QBO) of stratospheric winds, and can amount to plus or minus 15% at 300 nm and plus or minus 5% at 310 nm (or erythemal irradiance) at the equator and at middle latitudes. Near the equator, the interannual variability of ozone amounts and UV irradiance caused by the combination of the 2.3 year QBO and annual cycles implies that there is about a 5-year periodicity in UVB variability. At higher latitudes, the appearance of the interannual UVB maximum is predicted by the QBO, but without the regular periodicity. The 5-year periodic QBO effects on UVB irradiance are larger than the currently evaluated long-term changes caused by the decrease in ozone amounts.

  17. Interannual Variation in Phytoplankton Primary Production at a Global Scale

    NASA Technical Reports Server (NTRS)

    Rousseaux, Cecile Severine; Gregg, Watson W.

    2013-01-01

    We used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of four phytoplankton groups to the total primary production. First, we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998-2011. Globally, diatoms contributed the most to the total phytoplankton production ((is)approximately 50%, the equivalent of 20 PgC·y1). Coccolithophores and chlorophytes each contributed approximately 20% ((is) approximately 7 PgC·y1) of the total primary production and cyanobacteria represented about 10% ((is) approximately 4 PgC·y1) of the total primary production. Primary production by diatoms was highest in the high latitudes ((is) greater than 40 deg) and in major upwelling systems (Equatorial Pacific and Benguela system). We then assessed interannual variability of this group-specific primary production over the period 1998-2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4% (1-2 PgC·y1). We assessed the effects of climate variability on group-specific primary production using global (i.e., Multivariate El Niño Index, MEI) and "regional" climate indices (e.g., Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p (is) less than 0.05) between the MEI and the group-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatoms/cyanobacteria) and in the North Atlantic (chlorophytes and coccolithophores). We found that climate variability as indicated by SAM had only a limited effect

  18. North American Gross Primary Productivity: Regional Characterization and Interannual Variability

    NASA Astrophysics Data System (ADS)

    Baker, I. T.; Denning, A.; Stockli, R.

    2009-12-01

    Seasonality and variability in North American photosynthetic activity are investigated. Using the Simple Biosphere Model (SiB) we simulate 24 years (1983-2006) and evaluate regional and seasonal contribution to annual mean Gross Primary Productivity (GPP) as well as its interannual variability. The largest productivity occurs in tropical Mexico, the southeast U.S. and small areas in the Pacific Northwest. Annual variability is largest in tropical Mexico, the desert Southwest, and the Midwestern corridor that separates the eastern forests from the intermountain west. We find that several areas (Midwest, Northeast, SouthWest, Boreal Canada) have an elevated contribution to interannual variability when compared to other regions, but no single region or season consistently determines continental annual GPP anomaly on an annual basis. GPP variability in NA is highly heterogeneous in space and time. We find that GPP variability is generally dependent upon soil moisture in low- and mid-latitudes, and on temperature in the north. Soil moisture is a better metric than raw precipitation as it integrates precipitation events temporally. EOF analysis shows no significance on an annual basis, but a band from the central plains through New England shows a coherent signal for springtime GPP anomalies. As the springtime anomaly is the largest contributor to the annual GPP variability in almost half of the years simulated (11 of 24), we can posit that this region has significant influence over annual North American GPP variability. However, when regressed against climate modes such as El Nino Southern Oscillation (ENSO), Arctic Oscillation (AO) or Pacific-North America (PNA) patterns, we find that no climate mode can be associated with variability over the entire region highlighted by the EOF analysis. Furthermore, we find that while a general response to temperature is seen (warmer spring implies longer growing season implies anomalous GPP uptake of carbon), in some regions the

  19. Interannual atmospheric variability forced by the deep equatorial Atlantic Ocean.

    PubMed

    Brandt, Peter; Funk, Andreas; Hormann, Verena; Dengler, Marcus; Greatbatch, Richard J; Toole, John M

    2011-05-26

    Climate variability in the tropical Atlantic Ocean is determined by large-scale ocean-atmosphere interactions, which particularly affect deep atmospheric convection over the ocean and surrounding continents. Apart from influences from the Pacific El Niño/Southern Oscillation and the North Atlantic Oscillation, the tropical Atlantic variability is thought to be dominated by two distinct ocean-atmosphere coupled modes of variability that are characterized by meridional and zonal sea-surface-temperature gradients and are mainly active on decadal and interannual timescales, respectively. Here we report evidence that the intrinsic ocean dynamics of the deep equatorial Atlantic can also affect sea surface temperature, wind and rainfall in the tropical Atlantic region and constitutes a 4.5-yr climate cycle. Specifically, vertically alternating deep zonal jets of short vertical wavelength with a period of about 4.5 yr and amplitudes of more than 10 cm s(-1) are observed, in the deep Atlantic, to propagate their energy upwards, towards the surface. They are linked, at the sea surface, to equatorial zonal current anomalies and eastern Atlantic temperature anomalies that have amplitudes of about 6 cm s(-1) and 0.4 °C, respectively, and are associated with distinct wind and rainfall patterns. Although deep jets are also observed in the Pacific and Indian oceans, only the Atlantic deep jets seem to oscillate on interannual timescales. Our knowledge of the persistence and regularity of these jets is limited by the availability of high-quality data. Despite this caveat, the oscillatory behaviour can still be used to improve predictions of sea surface temperature in the tropical Atlantic. Deep-jet generation and upward energy transmission through the Equatorial Undercurrent warrant further theoretical study.

  20. Response of tree cover to interannual rainfall variability: the balance of direct and indirect effects

    NASA Astrophysics Data System (ADS)

    Yu, K.; D'Odorico, P.; Saha, M.; Ratajczak, Z.

    2015-12-01

    Climate change studies predict an increase both in seasonal and interannual rainfall variability. The impact of such variability on vegetation composition and ecosystem processes is not well understood. Using satellite data or model simulations, previous studies have reported mixed responses of tree cover to interannual rainfall variability in the tropic (i.e., neutral, positive, or negative). The underlying mechanisms behind such patterns, however, are still unclear. This study uses satellite data and develops a new mechanistic model to investigate the response of tree cover to increasing interannual rainfall variability along Kalahari Transect in Southern Africa. This model accounts for the competition between trees and grasses in access to soil water, fire-induced disturbance, and a demographic bottleneck in tree recruitment. Both satellite data and model results show an increase in tree cover with increasing interannual rainfall fluctuations in dry environments (i.e., mean annual rainfall, MAP<700 mm) but a decrease in tree cover in wet environments (i.e., MAP>700 mm). In dry environments, an increase in interannual rainfall variability disfavors grasses with shallow roots, thereby reducing fire-induced mortality in tree seedlings and opening windows of opportunity for tree recruitment (i.e., indirect effects). In wet environments, an increase in interannual rainfall variability leads to more instances of mass flow below the rooting zone of tree seedlings and thus reduces tree recruitment rate (i.e., direct effects). This study highlights the importance of accounting for the direct effects of rainfall variability on trees and the indirect effects mediated by tree-grass interactions to better understand how tree cover respond to increase in rainfall variability along rainfall gradients.

  1. Sensitivity of the interannual variability of mineral aerosol simulations to meteorological forcing dataset

    NASA Astrophysics Data System (ADS)

    Smith, Molly B.; Mahowald, Natalie M.; Albani, Samuel; Perry, Aaron; Losno, Remi; Qu, Zihan; Marticorena, Beatrice; Ridley, David A.; Heald, Colette L.

    2017-03-01

    Interannual variability in desert dust is widely observed and simulated, yet the sensitivity of these desert dust simulations to a particular meteorological dataset, as well as a particular model construction, is not well known. Here we use version 4 of the Community Atmospheric Model (CAM4) with the Community Earth System Model (CESM) to simulate dust forced by three different reanalysis meteorological datasets for the period 1990-2005. We then contrast the results of these simulations with dust simulated using online winds dynamically generated from sea surface temperatures, as well as with simulations conducted using other modeling frameworks but the same meteorological forcings, in order to determine the sensitivity of climate model output to the specific reanalysis dataset used. For the seven cases considered in our study, the different model configurations are able to simulate the annual mean of the global dust cycle, seasonality and interannual variability approximately equally well (or poorly) at the limited observational sites available. Overall, aerosol dust-source strength has remained fairly constant during the time period from 1990 to 2005, although there is strong seasonal and some interannual variability simulated in the models and seen in the observations over this time period. Model interannual variability comparisons to observations, as well as comparisons between models, suggest that interannual variability in dust is still difficult to simulate accurately, with averaged correlation coefficients of 0.1 to 0.6. Because of the large variability, at least 1 year of observations at most sites are needed to correctly observe the mean, but in some regions, particularly the remote oceans of the Southern Hemisphere, where interannual variability may be larger than in the Northern Hemisphere, 2-3 years of data are likely to be needed.

  2. Enhanced interannual precipitation variability increases plant functional diversity that in turn ameliorates negative impact on productivity.

    PubMed

    Gherardi, Laureano A; Sala, Osvaldo E

    2015-12-01

    Although precipitation interannual variability is projected to increase due to climate change, effects of changes in precipitation variance have received considerable less attention than effects of changes in the mean state of climate. Interannual precipitation variability effects on functional diversity and its consequences for ecosystem functioning are assessed here using a 6-year rainfall manipulation experiment. Five precipitation treatments were switched annually resulting in increased levels of precipitation variability while maintaining average precipitation constant. Functional diversity showed a positive response to increased variability due to increased evenness. Dominant grasses decreased and rare plant functional types increased in abundance because grasses showed a hump-shaped response to precipitation with a maximum around modal precipitation, whereas rare species peaked at high precipitation values. Increased functional diversity ameliorated negative effects of precipitation variability on primary production. Rare species buffered the effect of precipitation variability on the variability in total productivity because their variance decreases with increasing precipitation variance.

  3. Controls on interannual variability in lightning-caused fire activity in the western US

    NASA Astrophysics Data System (ADS)

    Abatzoglou, John T.; Kolden, Crystal A.; Balch, Jennifer K.; Bradley, Bethany A.

    2016-04-01

    Lightning-caused wildfires account for a majority of burned area across the western United States (US), yet lightning remains among the more unpredictable spatiotemporal aspects of the fire environment and a challenge for both modeling and managing fire activity. A data synthesis of cloud-to-ground lightning strikes, climate and fire data across the western US from 1992 to 2013 was conducted to better understand geographic variability in lightning-caused wildfire and the factors that influence interannual variability in lightning-caused wildfire at regional scales. Distinct geographic variability occurred in the proportion of fires and area burned attributed to lightning, with a majority of fires in the interior western US attributed to lightning. Lightning ignition efficiency was highest across the western portion of the region due to the concomitance of peak lightning frequency and annual nadir in fuel moisture in mid-to-late summer. For most regions the number of total and dry lightning strikes exhibited strong interannual correlation with the number of lightning-caused fires, yet were a poor predictor of area burned at regional scales. Commonality in climate-fire relationships for regional annual area burned by lightning- versus human-ignited fires suggests climate conditions, rather than lightning activity, are the predominant control of interannual variability in area burned by lightning-caused fire across much of the western US.

  4. Understanding the Role of Interannual Variability and Momentum Transfer on Wind Energy

    NASA Astrophysics Data System (ADS)

    Koerner, S.; Brunsell, N. A.; Miller, L.; Mechem, D. B.

    2014-12-01

    Forecasting realistic wind power potential is essential for wind energy to assist with meeting future energy demands. Current wind power estimates rely on the use of mean climatological wind speeds. This approach to estimating wind power neglects the influence of momentum extraction by the turbines (i.e. turbine-turbine interactions) and interannual variability in windspeed. The present study will use a wind turbine parameterization within the Weather and Research Forecasting (WRF) model to assess the role of interannual and climatic variability on power extraction. The WRF model will be forced by NARR, and run from 1980-2010 to incorporate different climatic conditions over the central United States. Analysis focusses on the role of climate variability on wind power extraction; specifically on the role of drought and wet periods, as well as variability in the Great Plains Low Level Jet. In addition, WRF will be used to assess the impact of wind turbines on each term of the momentum budget. Understanding the impact of interannual variability will improve our understanding of the role that wind power can play in meeting future energy demands.

  5. Interannual variability in the surface energy budget and evaporation over a large southern inland water in the United States

    NASA Astrophysics Data System (ADS)

    Zhang, Qianyu; Liu, Heping

    2013-05-01

    Understanding how the surface energy budget and evaporation over inland waters respond to climate change and variability remains limited. Here we report 2 year measurements of the surface energy budget using the eddy covariance method over Ross Barnett Reservoir, Mississippi, USA, for 2008 and 2009. Annual mean sensible (H) and latent (LE) heat fluxes in 2008 were 9.5%, and 10.0% greater than in 2009, respectively. Most of the interannual variations in the surface energy fluxes and meteorological variables primarily occurred in the cool seasons from October to March, which was enhanced by frequent large wind events associated with cold front passages. These large wind events greatly promoted H and LE exchange and produced H and LE pulses that increased variations in H and LE between these two cool seasons. In the warm seasons from April to September, H and LE pulses were also present, which largely increased variations in LE and dampened those in H between the two warm seasons. The H and LE pulses contributed to approximately 50% of the annual H and 28% of the annual LE, although they only covered about 16% of the entire year. The interannual variations in H and LE pulses contributed to about 78% of the interannual variations in H and 40% of those in LE. Our results imply that the increased interannual variability in cold front activities as a result of climate change would amplify interannual variations in the evaporation and the surface energy exchange over inland waters in this region.

  6. The Effect of the Interannual Variability of the OH Sink on the Interannual Variability of the Atmospheric Methane Mixing Ratio and Carbon Stable Isotope Composition

    NASA Astrophysics Data System (ADS)

    Guillermo Nuñez Ramirez, Tonatiuh; Houweling, Sander; Marshall, Julia; Williams, Jason; Brailsford, Gordon; Schneising, Oliver; Heimann, Martin

    2013-04-01

    The atmospheric hydroxyl radical concentration (OH) varies due to changes in the incoming UV radiation, in the abundance of atmospheric species involved in the production, recycling and destruction of OH molecules and due to climate variability. Variability in carbon monoxide emissions from biomass burning induced by El Niño Southern Oscillation are particularly important. Although the OH sink accounts for the oxidation of approximately 90% of atmospheric CH4, the effect of the variability in the distribution and strength of the OH sink on the interannual variability of atmospheric methane (CH4) mixing ratio and stable carbon isotope composition (δ13C-CH4) has often been ignored. To show this effect we simulated the atmospheric signals of CH4 in a three-dimensional atmospheric transport model (TM3). ERA Interim reanalysis data provided the atmospheric transport and temperature variability from 1990 to 2010. We performed simulations using time dependent OH concentration estimations from an atmospheric chemistry transport model and an atmospheric chemistry climate model. The models assumed a different set of reactions and algorithms which caused a very different strength and distribution of the OH concentration. Methane emissions were based on published bottom-up estimates including inventories, upscaled estimations and modeled fluxes. The simulations also included modeled concentrations of atomic chlorine (Cl) and excited oxygen atoms (O(1D)). The isotopic signal of the sources and the fractionation factors of the sinks were based on literature values, however the isotopic signal from wetlands and enteric fermentation processes followed a linear relationship with a map of C4 plant fraction. The same set of CH4emissions and stratospheric reactants was used in all simulations. Two simulations were done per OH field: one in which the CH4 sources were allowed to vary interannually, and a second where the sources were climatological. The simulated mixing ratios and

  7. Interannual variability of the Adriatic Sea circulation

    NASA Astrophysics Data System (ADS)

    Beg Paklar, Gordana; Sepic, Jadranka; Grbec, Branka; Dzoic, Tomislav; Kovac, Zarko; Ivatek-Sahdan, Stjepan

    2016-04-01

    The Regional Ocean Modeling System (ROMS) was implemented in order to reproduce interannual variability of the Adriatic Sea circulation. Simulations and model result analysis were performed for a three-year period from 1st January 2011 to 31st December 2013. ROMS model run was forced with realistic atmospheric fields obtained from meteorological model Aladin, climatological river discharges, tides and Mediterranean circulation imposed at the southern open boundary. Atmospheric forcing included momentum, heat and water fluxes calculated interactively from the Aladin surface fields during ROMS model simulations. Model results were compared with available CTD and ADCP measurements and discussed in the light of the climatological circulation and thermohaline properties of the Adriatic Sea and its coastal areas. Interannual variability in the Adriatic circulation is related to the prevailing atmospheric conditions, changes in the hydrological conditions and water mass exchange at the Otranto Strait. Basic features of the Adriatic circulation - basin-wide cyclonic circulation with several embedded smaller cyclonic gyres around main pits - are well reproduced by ROMS model. Modelled temperatures and salinities are within corresponding seasonal intervals, although measured profiles generally indicate stronger stratification than modelled ones. Summer circulation in 2011 with current reversal obtained along the eastern Adriatic coast was related to the sampling results of the early fish stages as well as to ARGO drifter movements. Simulated fields from the Adriatic scale model were used to prescribe the initial and open boundary conditions for the interannual simulation in the middle Adriatic coastal domain.

  8. Interannual and interdecadal variability in 335 years of central England temperatures.

    PubMed

    Plaut, G; Ghil, M; Vautard, R

    1995-05-05

    Understanding the natural variability of climate is important for predicting its near-term evolution. Models of the oceans' thermohaline and wind-driven circulation show low-frequency oscillations. Long instrumental records can help validate the oscillatory behavior of these models. Singular spectrum analysis applied to the 335-year-long central England temperature (CET) record has identified climate oscillations with interannual (7- to 8-year) and interdecadal (15- and 25-year) periods, probably related to the North Atlantic's wind-driven and thermohaline circulation, respectively. Statistical prediction of oscillatory variability shows CETs decreasing toward the end of this decade and rising again into the middle of the next.

  9. Climate and developmental plasticity: interannual variability in grapevine leaf morphology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The shape of leaves are dynamic, changing over evolutionary time between species, within a single plant producing different shaped leaves at successive nodes, during the development of a single leaf as it allometrically expands, and in response to the environment. Notably, strong correlations betwee...

  10. Interannual Variability of Snow Water Equivalent (SWE) over Western Himalayas

    NASA Astrophysics Data System (ADS)

    Tiwari, Sarita; Kar, Sarat C.; Bhatla, R.

    2016-04-01

    Considering the importance of snow and glaciers in the Himalayas for understanding the water cycle and for water resource management of the rivers originating from the Himalayan, interannual variability of snow accumulation process over Himalayas and surrounding region has been studied using snow water equivalent (SWE) data. Remote sensing data from National Snow and Ice Data Centre have been used. These data have been compared against ground (in situ) observations of SWE measured at several gauge stations in the Indian part of the Satluj River basin. Accumulated SWE from remote sensing data and ground observations in the Satluj River basin have good and significant correlation. These data have also been compared against the Climate Forecast System Reanalysis and the European Centre for Medium Range Weather Forecast reanalysis-Interim (ERA-I). Upper air and surface data from the reanalyses have also been used to examine the atmospheric conditions when snowfall occurs and snow accumulates for the season. In this study, it is found that there is large interannual variation in SWE over western Himalayas and Satluj River basin (domain of interest). During excess years of snowfall, strong westerly winds are observed at 500 hPa over India. In wind anomaly, a cyclonic circulation is seen over northern parts of India with a deep trough along Pakistan, Rajasthan and Gujarat region. As a consequence of this trough, a moisture convergence zone is established in the region leading to more amount of snowfall. At the same time, during excess snow accumulation years, the air temperature from the surface to 500 hPa is colder than other years enabling the fallen snow to accumulate through the season.

  11. Sea level trends and interannual variability in the Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Torres, R.; Tsimplis, M.

    2012-04-01

    Sea level trends and interannual variability has been investigated in the Caribbean Sea using altimetry and tide gauge time series from 19 stations. Relative sea level trends range between -2.0 and 10.7 mm/y depending on the length of the available record. Records from stations longer than 40 years converge toward values between 1.2 - 5.2 mm/yr, still a significant range which in some stations is less and in some other significantly larger than the global average. The longest station, Cristobal (102 years) shows a trend of 1.9 mm/yr and, in addition a significant acceleration of 1.6±0.3 mm/y/cy. The observed sea level trends are not affected by the atmospheric pressure effect, within the levels of significance. They are also the same (within the levels of significance) at all seasons. Altimetry shows trends (over 18 years of data) with values up to 5.2 mm/y. In some areas the values are statistically insignificant, but at no areas statistically significant negative values are found. Steric trends from the top 800 m (over the period of altimetric observations) have a basin average trend of 1 mm/y, but it shows large spatial variability with negative trends of -7 mm/y in the Yucatan Basin and positive trends up to 4.9 mm/y in the Venezuela Basin. Decadal trends were found to vary significantly at tide-gauge records as well as altimetric and steric measurements. We further explore the residual interannual variability by comparison with surface wind and climatic indices. This analysis is supported by the Lloyd's Register Trust Fund project Marine Extremes.

  12. Projections of Southern Hemisphere atmospheric circulation interannual variability

    NASA Astrophysics Data System (ADS)

    Grainger, Simon; Frederiksen, Carsten S.; Zheng, Xiaogu

    2017-02-01

    An analysis is made of the coherent patterns, or modes, of interannual variability of Southern Hemisphere 500 hPa geopotential height field under current and projected climate change scenarios. Using three separate multi-model ensembles (MMEs) of coupled model intercomparison project phase 5 (CMIP5) models, the interannual variability of the seasonal mean is separated into components related to (1) intraseasonal processes; (2) slowly-varying internal dynamics; and (3) the slowly-varying response to external changes in radiative forcing. In the CMIP5 RCP8.5 and RCP4.5 experiments, there is very little change in the twenty-first century in the intraseasonal component modes, related to the Southern annular mode (SAM) and mid-latitude wave processes. The leading three slowly-varying internal component modes are related to SAM, the El Niño-Southern oscillation (ENSO), and the South Pacific wave (SPW). Structural changes in the slow-internal SAM and ENSO modes do not exceed a qualitative estimate of the spatial sampling error, but there is a consistent increase in the ENSO-related variance. Changes in the SPW mode exceed the sampling error threshold, but cannot be further attributed. Changes in the dominant slowly-varying external mode are related to projected changes in radiative forcing. They reflect thermal expansion of the tropical troposphere and associated changes in the Hadley Cell circulation. Changes in the externally-forced associated variance in the RCP8.5 experiment are an order of magnitude greater than for the internal components, indicating that the SH seasonal mean circulation will be even more dominated by a SAM-like annular structure. Across the three MMEs, there is convergence in the projected response in the slow-external component.

  13. Interannual Variability of the Mars Atmosphere at Aphelion

    NASA Astrophysics Data System (ADS)

    Shirley, J. H.; McConnochie, T. H.; Kleinboehl, A.; Schofield, J. T.; Kass, D. M.; Heavens, N. G.; McCleese, D. J.

    2012-12-01

    Mars' aphelion occurs in late northern spring, less than one Martian month prior to the northern summer solstice. Due to the large eccentricity (0.093) of the Mars orbit, solar irradiance is about one third lower at aphelion than at perihelion. Atmospheric temperatures and dust aerosol loading reach minimum values in the aphelion season, while water ice cloud amounts (particularly in the equatorial regions) attain annual maxima. Prior investigations indicate that the aphelion season Mars climate is highly repeatable from year to year. We compare zonally-averaged limb-sounding temperature and aerosol opacity profiles obtained by the Mars Global Surveyor Thermal Emission Spectrometer (TES) and the Mars Reconnaissance Orbiter Mars Climate Sounder (MCS) instruments during the aphelion seasons for 6 Mars Years (MY 25-27 and 29-31). While the results from both instruments are in good agreement for most latitude bins in middle latitudes, we find substantial interannual differences in temperature and dust and ice aerosol opacity at higher latitudes. Year-to-year variability of the polar atmosphere is evident in data from both TES and MCS, considered both separately and in combination.

  14. Intercomparison of interannual changes in NDVI from PAL and GIMMS in relation to evapotranspiration over northern Asia

    NASA Astrophysics Data System (ADS)

    Suzuki, R.; Masuda, K.; Dye, D.

    2004-12-01

    Vegetation over an extensive area influences actual evapotranspiration (ET) from the land to the atmosphere mainly through transpiration activity. The authors' previous study (Suzuki and Masuda, 2004. J Meteor Soc Japan, 82, 1233 -- 1241) found an interannual covariability between ET and the Normalized Difference Vegetation Index (NDVI) over a continental-scale land surface. This result suggested that vegetation controls interannual variation in ET, and therefore vegetation change must be considered to predict future climate. In this prior study, NDVI data from the Pathfinder AVHRR Land (PAL) dataset were analyzed. However, studies of NDVI interannual change are subject to uncertainty, because NDVI data often contain errors associated with sensor- and atmosphere-related effects. This study is aimed toward reducing this uncertainty by employing another major NDVI dataset, from the Global Inventory Monitoring and Modeling Studies (GIMMS) group, in addition to PAL. GIMMS-NDVI data were produced with a calibration method that differs from the one employed for PAL-NDVI data. An intercomparison of the PAL-NDVI and GIMMS-NDVI datasets provide an effective basis for further analysis of the covariability of NDVI and ET interannual changes. The analysis was carried out for the northern Asia region from 1982 to 2000. 19-year interannual changes (monthly anomalies) in the PAL-NDVI and GIMMS-NDVI values were compared. The correlation coefficient (R) in summer months exhibits high positive values (over 0.8 in June). This result indicates that PAL-NDVI and GIMMS-NDVI display similar interannual variation for active growing season months. Interannual change in PAL-NDVI and GIMMS-NDVI were both compared with interannual change in model-assimilated ET. Although the R between GIMMS-NDVI and ET is slightly less than for PAL-NDVI and ET, for both NDVI datasets the annual maximum correlation with ET occurs in June, which is near the central period of the growing season. A positive

  15. Effects of Uncertainty in TRMM Precipitation Radar Path Integrated Attenuation on Interannual Variations of Tropical Oceanic Rainfall

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Fitzjarrald, Dan E.; Kummerow, Christian D.; Arnold, James E. (Technical Monitor)

    2002-01-01

    Considerable uncertainty surrounds the issue of whether precipitation over the tropical oceans (30 deg N/S) systematically changes with interannual sea-surface temperature (SST) anomalies that accompany El Nino (warm) and La Nina (cold) events. Time series of rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM Precipitation Radar (PR) over the tropical oceans show marked differences with estimates from two TRMM Microwave Imager (TMI) passive microwave algorithms. We show that path-integrated attenuation derived from the effects of precipitation on the radar return from the ocean surface exhibits interannual variability that agrees closely with the TMI time series. Further analysis of the frequency distribution of PR (2A25 product) rain rates suggests that the algorithm incorporates the attenuation measurement in a very conservative fashion so as to optimize the instantaneous rain rates. Such an optimization appears to come at the expense of monitoring interannual climate variability.

  16. An interpretation of the interannual mass trend change over the Indochina Peninsula observed by GRACE data

    NASA Astrophysics Data System (ADS)

    Yamamoto, K.; Fukuda, Y.; Nakaegawa, T.; Hasegawa, T.; Taniguchi, M.

    2010-12-01

    In Research Institute for Humanity and Nature, a project “Human Impacts on Urban Subsurface Environments” to assess impacts of human activities on urban subsurface environment in several Asian developing cities is now in progress. Although one of the main purposes of the project is to investigate local groundwater systems on and around the urban cities, the project also aims to understand large-scale landwater movements including the areas, and Gravity Recovery and Climate Experiment (GRACE) satellite gravity data is used for the purpose. In the previous study (Yamamoto et al., 2010), we recovered the regional-scale interannual landwater mass variation over the Indochina Peninsula, which includes one of the test cities in the project, i.e. Bangkok, Thailand, by using GRACE data. The recovered mass variation showed the change of the interannual trend at around the beginning of 2005: it decreased up to the beginning of 2005, and after that, increased up to 2009. The compared results with observed/modeled hydrological and meteorological data sets showed that the observed trend change did not caused by regional human activities, e.g. excessive groundwater pumping, but caused by global-scale meteorological phenomena. In fact, the interannual mass variation showed high correlation with the climate index represents the intensity of Indian Ocean Dipole (IOD) phenomena. In this study, we investigated the correlation mechanism between the interannual mass change in the Indochina Peninsula and the IOD phenomena, which is the spatial anomaly pattern of sea surface temperature. We firstly made the moisture flux data sets in the GRACE mission duration by using atmospheric objective reanalysis data. The obtained flux pattern was discussed by comparing with the typical flux pattern during the pure IOD years estimated by Ummenhofer et al., 2009. Further, the moisture flux over the Indochina Peninsula was assessed whether the value is quantitatively agreeable by comparing with

  17. Interannual and Decadal Variability of Summer Rainfall over South America

    NASA Technical Reports Server (NTRS)

    Zhou, Jiayu; Lau, K.-M.

    1999-01-01

    Using the CPC (Climate Prediction Center) Merged Analysis of Precipitation product along with the Goddard Earth Observing System reanalysis and the Climate Analysis Center sea surface temperature (SST) data, we conduct a diagnostic study of the interannual and decadal scale variability of summer rainfall over South America. Results show three leading modes of rainfall variation identified with interannual, decadal, and long-term trend variability. Together, these modes explain more than half the total variance. The first mode is highly correlated with El Nino/southern oscillation (ENSO), showing severe drought over Northeast Brazil and copious rainfall over the Ecuador coast and the area of Uruguay-Southern Brazil in El Nino years. This pattern is attributed to the large scale zonal shift of the Walker circulation and local Hadley cell anomaly induced by positive (negative) SST anomaly over the eastern (western) equatorial Pacific. In El Nino years, two convective belts indicated by upper tropospheric velocity potential trough and mid-tropospheric rising motion, which are somewhat symmetric about the equator, extend toward the northeast and the southeast into the tropical North and South Atlantic respectively. Sandwiched between the ascent is a region of descending motion over Northeast Brazil. The southern branch of the anomalous Hadley cell is dynamically linked to the increase of rainfall over Uruguay-Southern Brazil. The regional response of anomalous circulation shows a stronger South American summer monsoon and an enhanced (weakened) subtropical high over the South Atlantic (South Pacific) Ocean. The decadal variation displays a meridional shift of the Intertropical Convergence Zone (ITCZ), which is tie to the anomalous cross-equatorial SST gradient over the Atlantic and the eastern Pacific. In conjunction with this mode is a large scale mass swing between the polar regions and midlatitudes in both hemispheres. Over the South Atlantic and the South Pacific

  18. Analysis of the Relationship Between Climate and NDVI Variability at Global Scales

    NASA Technical Reports Server (NTRS)

    Zeng, Fan-Wei; Collatz, G. James; Pinzon, Jorge; Ivanoff, Alvaro

    2011-01-01

    interannual variability in modeled (CASA) C flux is in part caused by interannual variability in Normalized Difference Vegetation Index (NDVI) Fraction of Photosynthetically Active Radiation (FPAR). This study confirms a mechanism producing variability in modeled NPP: -- NDVI (FPAR) interannual variability is strongly driven by climate; -- The climate driven variability in NDVI (FPAR) can lead to much larger fluctuation in NPP vs. the NPP computed from FPAR climatology

  19. Harnessing Historical Climate Variability to Assess Multivariate Climate Changes

    NASA Astrophysics Data System (ADS)

    Mahony, C. R.; Cannon, A. J.; Aitken, S. N.

    2015-12-01

    Climate is intrinsically multivariate—the collective influence of various aspects of weather at different times of year. A central challenge of climate change impact analysis is therefore to characterize changes in multiple temperature and precipitation variables simultaneously. Historical climate variability provides key context for relating climate variables to each other and assessing collective deviations from historical climate conditions. We have developed a Mahalanobian probability metric to describe spatial and temporal climatic dissimilarity in terms of local interannual climatic variability. Our approach is particularly suited to evaluation of climate analogs in space and time, but also facilitates multivariate extensions to several prominent indices of climate change. We use this metric to detect the departure of multivariate climate conditions from the historical range of local variability across North America and to identify regions that are particularly susceptible to emergence of no-analog climates. With respect to interpreting climate extremes, some critical considerations emerge from this research. In particular, we highlight the potential for temporal aggregation to exaggerate the statistical significance of extreme conditions, and the dilemma of identifying an appropriate statistical distribution for precipitation across both space and time. Despite the challenges of interpreting the specific impacts associated with multivariate climate changes and extremes, expressing these conditions relative to historical climate variability provides a useful first approximation of their ecological and socioeconomic significance. Figure Caption: Demonstration of the use of the chi distribution to measure spatial climatic dissimilarity in terms of local interannual climatic variability.

  20. Marginal Lands Gross Primary Production Dominate Atmospheric CO2 Interannual Variations

    NASA Astrophysics Data System (ADS)

    Ahlström, A.; Raupach, M. R.; Schurgers, G.; Arneth, A.; Jung, M.; Reichstein, M.; Smith, B.

    2014-12-01

    Since the 1960s terrestrial ecosystems have acted as a substantial sink for atmospheric CO2, sequestering about one quarter of anthropogenic emissions in an average year. Variations in this land carbon sink are also responsible for most of the large interannual variability in atmospheric CO2 concentrations. While most evidence places the majority of the sink in highly productive forests and at high latitudes experiencing warmer and longer growing seasons, the location and the processes governing the interannual variations are still not well characterised. Here we evaluate the hypothesis that the long-term trend and the variability in the land CO2 sink are respectively dominated by geographically distinct regions: the sink by highly productive lands, mainly forests, and the variability by semi-arid or "marginal" lands where vegetation activity is strongly limited by water and therefore responds strongly to climate variability. Using novel analysis methods and data from both upscaled flux-tower measurements and a dynamic global vegetation model, we show that (1) the interannual variability in the terrestrial CO2 sink arises mainly from variability in terrestrial gross primary production (GPP); (2) most of the interannual variability in GPP arises in tropical and subtropical marginal lands, where negative anomalies are driven mainly by warm, dry conditions and positive anomalies by cool, wet conditions; (3) the variability in the GPP of high-latitude marginal lands (tundra and shrublands) is instead controlled by temperature and light, with warm bright conditions resulting in positive anomalies. The influence of ENSO (El Niño-Southern Oscillation) on the growth rate of atmospheric CO2 concentrations is mediated primarily through climatic effects on GPP in marginal lands, with opposite signs in subtropical and higher-latitude regions. Our results show that the land sink of CO2 (dominated by forests) and its interannual variability (dominated by marginal lands) are

  1. The Arctic Predictability and Prediction on Seasonal-to-Interannual TimEscales (APPOSITE) data set version 1

    NASA Astrophysics Data System (ADS)

    Day, Jonathan J.; Tietsche, Steffen; Collins, Mat; Goessling, Helge F.; Guemas, Virginie; Guillory, Anabelle; Hurlin, William J.; Ishii, Masayoshi; Keeley, Sarah P. E.; Matei, Daniela; Msadek, Rym; Sigmond, Michael; Tatebe, Hiroaki; Hawkins, Ed

    2016-06-01

    Recent decades have seen significant developments in climate prediction capabilities at seasonal-to-interannual timescales. However, until recently the potential of such systems to predict Arctic climate had rarely been assessed. This paper describes a multi-model predictability experiment which was run as part of the Arctic Predictability and Prediction On Seasonal to Interannual Timescales (APPOSITE) project. The main goal of APPOSITE was to quantify the timescales on which Arctic climate is predictable. In order to achieve this, a coordinated set of idealised initial-value predictability experiments, with seven general circulation models, was conducted. This was the first model intercomparison project designed to quantify the predictability of Arctic climate on seasonal to interannual timescales. Here we present a description of the archived data set (which is available at the British Atmospheric Data Centre), an assessment of Arctic sea ice extent and volume predictability estimates in these models, and an investigation into to what extent predictability is dependent on the initial state. The inclusion of additional models expands the range of sea ice volume and extent predictability estimates, demonstrating that there is model diversity in the potential to make seasonal-to-interannual timescale predictions. We also investigate whether sea ice forecasts started from extreme high and low sea ice initial states exhibit higher levels of potential predictability than forecasts started from close to the models' mean state, and find that the result depends on the metric. Although designed to address Arctic predictability, we describe the archived data here so that others can use this data set to assess the predictability of other regions and modes of climate variability on these timescales, such as the El Niño-Southern Oscillation.

  2. Can the teleconnection indices explain the interannual variability of Daphnia phenology ? A case study in Lake Iseo, northern Italy.

    NASA Astrophysics Data System (ADS)

    Beluzzi, Stefano; Leoni, Barbara; Salmaso, Nico; Manca, Marina

    2013-04-01

    In the last years, increasing interest has been shown on the impact of inter-annual climate variability on zooplankton. Several teleconnection indices have been successfully applied in order to explain inter-annual variations in zooplankton and phytoplankton seasonal dynamics. During the winter months (December-February), the East Atlantic pattern (EADJF) and the Eastern Mediterranean Pattern (EMPDJF) showed a clear relationship with the variables directly connected with the winter climate and limnological variables in the large lakes south of the Alps. A recent study carried out in the lakes Maggiore and Garda confirmed that the impact of the winter large scale atmospheric patterns was detectable also on the phenology of Daphnia populations. We extended the same approach to zooplankton of Lake Iseo, the fourth largest and deepest italian lake, with costant characteristic of meso-eutrophy during last decades. We analysed data from 1998 to 2012, focusing on population dynamics of Daphnia sp., the most important larger filter feeder in this lake. The results showed a link between the interannual climate fluctuations and the development of Daphnia. Our observations are consistent with the patterns obtained in the lakes Maggiore and Garda. Overall, the results confirm that these indices may help to detect and predict the effect of the impact of climate change on populations and freshwater ecosystems.

  3. Seasonal and interannual changes in cirrus

    NASA Technical Reports Server (NTRS)

    Wylie, Donald P.

    1990-01-01

    Statistics on cirrus clouds using the multispectral data from the GOES/VAS satellite have been collected since 1985. The method used to diagnose cirrus clouds and a summary of the first two years of data was given in Wylie and Menzel (1989) and at the 1988 FIRE meeting in Vail, CO. This study was expanded to three years of data which allows a more detailed discussion of the geographical and seasonal changes in cloud cover. Interannual changes in cloud cover also were studied. GOES/VAS cloud retrievals also were compared to atmospheric dynamic parameters and to radiative attenuation data taken by a lidar. Some of the highlights of these studies are discussed.

  4. Interannual variations of NDVI over Africa and their relationship to ENSO: 1982-1995

    NASA Astrophysics Data System (ADS)

    Anyamba, Assaf

    1997-10-01

    A fourteen year monthly data set of Normalized Difference Vegetation Index (NDVI) measurements for Africa is used as a proxy indicator for interannual climate variability. The data have been analyzed at two temporal scales: short time scale, 2-5 years and long time scale, 14 years. Using standardized Principal Components Analysis (PCA), spatial and temporal patterns are extracted. The first five, and sometimes six components extracted represent patterns related to the time integral of NDVI, various modes of seasonality and anomalies related sensor degradation. There is evidence of two or more interannual patterns immediately following the seasonal components that are related to El Nino Southern Oscillation (ENSO). One of the modes of interannual variation detected, affecting most particularly East Africa and the Sahel, does not exhibit a consistent ENSO relationship. In particular instances the interannual components related to ENSO are separated into two components, a deficiency of the analysis technique to resolve phenomena that propagate over space. In order to examine the geographic patterns of ENSO manifestation, growing season anomaly maps are derived and fitted using trend surface techniques. The derived surfaces illustrate that there are two types of alternating patterns of ENSO manifestation over Southern Africa. Type I, characteristic of the 1986-87 and 1994-95 ENSO warm events, are characterized by movement from the southwest to the northeast, Type II, 1982-83 and 1991-92 events are characterized by a more or less stationary drought cell that shows limited movement but with a tendency to grow out in a cellular manner during the growing season. Analysis of the entire time series shows three dominant modes of interannual variability, the Sahel-East Africa component related to QBO, a southeastern Africa component centered over eastern Zimbabwe and Mozambique closely related to ENSO, and lastly an anomaly pattern centered over Botswana, South Africa and the

  5. Future changes of interannual variation of the Asian summer monsoon precipitation using the CMIP5

    NASA Astrophysics Data System (ADS)

    Kamizawa, Nozomi; Takahashi, Hiroshi G.

    2015-04-01

    The Asian summer monsoon (ASM) region is one of the most populated areas in the world. Since the life of people who live in the region and the industry are strongly dependent on the ASM precipitation, it is interested that how it would change under the circumstance of global warming. Many studies have reported that the mean ASM precipitation would increase by comparing the CMIP models' climatology. Although the changes in mean climate are important, the long-term changes of interannual variability in precipitation are also significant. This study investigated the long-term trend of interannual precipitation variation over the ASM region by using 22 CMIP5 models. The RCP4.5 scenario was used. To investigate the long-term trend of the interannual variation of the ASM precipitation, each model data was recreated to 2.5 degree resolution and a running standard deviation for 21 years of June-July-August (JJA) precipitation were calculated. Next, we created the coefficient variation (CV) by dividing the running standard deviation by the mean JJA precipitation. Then we run a Mann-Kendall test for the CV at each grid. There were more areas which were indicated a statistically significant increasing trend than a decreasing trend in the ASM region. 40.6% of the region indicated an increasing trend in the future. On the other hand, 16.8% of the area was indicated to have a decreasing trend. It was also common in the global scale that the there were more areas that indicated an increasing trend than a decreasing trend. We also divided the area into three groups: land, shore and open ocean. In the ASM region, the shore areas particularly had an increasing CV trend. To investigate the long-term changes of the interannual variability of the precipitation and the atmospheric circulation over the ASM region, we conducted a composite analysis for the five wettest and driest years for two periods: the early 21st century (2007-2031) and the late 21st century (2076-2100). The special

  6. Feedback Attributions to the Interannual Variation of the Dominant Modes of the East Asian Winter Monsoon

    NASA Astrophysics Data System (ADS)

    Li, Yana; Yang, Song

    2016-04-01

    This study investigates the interannual variation and feedback attributions of the East Asian Winter Monsoon for the period of 1979-2013. The variations of winter mean surface air temperature are dominated by two distinct principal modes, which account for 70.9% of the total variance. The interannual variation of the northern mode features high correlations with the variations of the Arctic Oscillation, the Siberia High, and the tropoical Indian Ocean Dipole, while the southern mode is strongly linked to the East Asia trough and the atmospheric circulation over the northwestern Pacific. To find the main factors which affect the two different modes, this study decomposes the surface air temperature interannual variation into various feedback attributions by applying a climate feedback-response analysis method. The results indicate that the surface cooling associated with the northern mode is mainly contributed by the feedback processes of atmospheric dynamics, cloud, and sensible heating. For the southern mode, the surface cooling is mainly attributed to the atmospheric dynamic process, sensible heating, and water vapor, while the oceanic dynamics and heat storage process induces a negative effect that warms the surface.

  7. Sole larval supply to coastal nurseries: Interannual variability and connectivity at interregional and interpopulation scales

    NASA Astrophysics Data System (ADS)

    Savina, M.; Lunghi, M.; Archambault, B.; Baulier, L.; Huret, M.; Le Pape, O.

    2016-05-01

    Simulating fish larval drift helps assess the sensitivity of recruitment variability to early life history. An individual-based model (IBM) coupled to a hydrodynamic model was used to simulate common sole larval supply from spawning areas to coastal and estuarine nursery grounds at the meta-population scale (4 assessed stocks), from the southern North Sea to the Bay of Biscay (Western Europe) on a 26-yr time series, from 1982 to 2007. The IBM allowed each particle released to be transported by currents, to grow depending on temperature, to migrate vertically depending on development stage, to die along pelagic stages or to settle on a nursery, representing the life history from spawning to metamorphosis. The model outputs were analysed to explore interannual patterns in the amounts of settled sole larvae at the population scale; they suggested: (i) a low connectivity between populations at the larval stage, (ii) a moderate influence of interannual variation in the spawning biomass, (iii) dramatic consequences of life history on the abundance of settling larvae and (iv) the effects of climate variability on the interannual variability of the larvae settlement success.

  8. The Seasonal and Interannual Variability of the Budgets of N2O and CCl3F

    NASA Technical Reports Server (NTRS)

    Wong, Sun; Prather, Michael J.; Rind, David H.

    1999-01-01

    The 6-year wind archives from the Goddard Institute for Space Studies/Global Climate-Middle Atmosphere Model (GISS/GCMAM) were in- put to the GISS/Harvard/Irvine Chemical Transport Model (G/H/I CTM) to study the seasonal and interannual variability of the budgets and distributions of nitrous oxide (N2O) and trichlorofluoromethane (CCl3F), with the corresponding chemical loss frequencies recycled and boundary conditions kept unchanged from year to year. The effects of ozone feedback and quasi-biennial oscillation (QBO) were not included. However, the role of circulation variation in driving the lifetime variability is investigated. It was found that the global loss rates of these tracers are related to the extratropical planetary wave activity, which drives the tropical upward mass flux. For N2O, a semiannual signal in the loss rate variation is associated with the interhemispheric asymmetry in the upper stratospheric wave activity. For CCl3F, the semiannual signal is weaker, associated with the comparatively uniform wave episodes in the lower stratosphere. The loss rates lag behind the wave activity by about 1-2 months. The interannual variation of the GCM generated winds drives the interannual variation of the annually averaged lifetime. The year-to-year variations of the annually averaged lifetimes can be about 3% for N2O and 4% for CCl3F.

  9. Interannual variation of convectively-coupled equatorial waves and their association with environmental factors

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Chen, Lin

    2016-12-01

    Convectively-coupled equatorial waves (CCEWs) are fundamental components of tropical convection, which are important for weather and climate prediction. However, their interannual variation mechanism has received limited attention to date. By employing 6-hourly satellite-based brightness temperature data from 1983 to 2009, this study investigates the interannual variation of three dominant CCEWs. The results show that the Kelvin wave and the n = 1 westward inertia gravity (WIG) wave display maximum variability over the central Pacific at the equator in boreal winter. Intensity variations in both waves show good correlation relationship with local thermodynamic condition (i.e., sea surface temperature and moisture) and local dynamic condition (i.e., vertically sheared zonal flow). Abundant humidity and weak vertically sheared zonal flow appear in the years of intensified wave activity, whereas less humidity and strong westerly sheared flows appear in the years of suppressed wave activity. Sensitivity numerical experiments show that background moisture are important for both waves, while wind shear can only impact n = 1 WIG wave. A westerly sheared flow tends to suppress the n = 1 WIG wave in the lower troposphere, and thus results in weakened wave growth. n = 1 equatorial Rossby (ER) wave displays maximum variability over the southern Pacific during boreal winter. Its intensity variation is poorly related with local environmental factors but is significantly correlated with El Niño-Southern Oscillation (ENSO) cycle. The results indicate that a different mechanism might be needed to explain the interannual variation of n = 1 ER wave.

  10. Interannual variability in net community production at the Western Antarctic Peninsula region (1997-2014)

    NASA Astrophysics Data System (ADS)

    Li, Zuchuan; Cassar, Nicolas; Huang, Kuan; Ducklow, Hugh; Schofield, Oscar

    2016-07-01

    In this study, we examined the interannual variability of net community production (NCP) in the Western Antarctic Peninsula (WAP) using in situ O2/Ar-NCP estimates (2008-2014) and satellite data (SeaWiFS and MODIS-Aqua) from 1997 to 2014. We found that NCP generally first peaks offshore and follows sea-ice retreat from offshore to inshore. Annually integrated NCP (ANCP) displays an onshore-to-offshore gradient, with coastal and shelf regions up to 8 times more productive than offshore regions. We examined potential drivers of interannual variability in the ANCP using an Empirical Orthogonal Function (EOF) analysis. The EOF's first mode explains ˜50% of the variance, with high interannual variability observed seaward of the shelf break. The first principal component is significantly correlated with the day of sea-ice retreat (R = -0.58, p < 0.05), as well as the Southern Annular Mode (SAM) and El Niño Southern Oscillation (ENSO) climate indices in austral spring. Although the most obvious pathway by which the day of sea-ice retreat influences NCP is by controlling light availability early in the growing season, we found that the effect of day of sea-ice retreat on NCP persists throughout the growing season, suggesting that additional controls, such as iron availability, are preconditioned or correlated to the day of sea-ice retreat.

  11. Mechanisms of Interannual Variations of the Meridional Overturning Circulation of the North Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    Cabanes, Cecile; Lee, Tong; Fu, Lee-Lueng

    2008-01-01

    The authors investigate the nature of the interannual variability of the meridional overturning circulation (MOC) of the North Atlantic Ocean using an Estimating the Circulation and Climate of the Ocean (ECCO) assimilation product for the period of 1993-2003. The time series of the first empirical orthogonal function of the MOC is found to be correlated with the North Atlantic Oscillation (NAO) index, while the associated circulation anomalies correspond to cells extending over the full ocean depth. Model sensitivity experiments suggest that the wind is responsible for most of this interannual variability, at least south of 40(deg)N. A dynamical decomposition of the meridional streamfunction allows a further look into the mechanisms. In particular, the contributions associated with 1) the Ekman flow and its depth-independent compensation, 2) the vertical shear flow, and 3) the barotropic gyre flowing over zonally varying topography are examined. Ekman processes are found to dominate the shorter time scales (1.5-3 yr), while for longer time scales (3-10 yr) the MOC variations associated with vertical shear flow are of greater importance. The latter is primarily caused by heaving of the pycnocline in the western subtropics associated with the stronger wind forcing. Finally, how these changes in the MOC affect the meridional heat transport (MHT) is examined. It is found that overall, Ekman processes explain a larger part of interannual variability (3-10 yr) for MHT (57%) than for the MOC (33%).

  12. Interannual variation of global net radiation flux as measured from space

    NASA Astrophysics Data System (ADS)

    Zhu, Ping; Wild, Martin; Ruymbeke, Michel; Thuillier, Gérard; Meftah, Mustapha; Karatekin, Ozgur

    2016-06-01

    The global net radiation flux (NRF) in and out of the climate system at the top of the atmosphere (TOA) varies at interannual time scales, reflecting the complexity of the processes responsible for attaining global energy equilibrium. These processes are investigated in this study using the previously unexplored data acquired by a bolometric type sensor installed in the PICARD microsatellite. The obtained anomalies in the NRF (PICARD-NRF) are compared to the global NRF changes at the TOA measured by the Clouds and Earth's Radiant Energy System mission (CERES-NRF). The interanual PICARD-NRF is strongly correlated with the matching period CERES-NRF; the bootstrapped correlation at the 95%(+0.85 and +0.97) confidence intervals is +0.93. Consistency in the interannual variability in the NRF derived by two completely independent measurement systems enhances confidence in the estimated magnitude of these variations. To reveal the possible drivers of the NRF interannual variability, the NRF values were compared with the multivariate El Niño-Southern Oscillation index.

  13. The Interannual Stability of Cumulative Frequency Distributions for Convective System Size and Intensity

    NASA Technical Reports Server (NTRS)

    Mohr, Karen I.; Molinari, John; Thorncroft, Chris D,

    2010-01-01

    The characteristics of convective system populations in West Africa and the western Pacific tropical cyclone basin were analyzed to investigate whether interannual variability in convective activity in tropical continental and oceanic environments is driven by variations in the number of events during the wet season or by favoring large and/or intense convective systems. Convective systems were defined from TRMM data as a cluster of pixels with an 85 GHz polarization-corrected brightness temperature below 255 K and with an area at least 64 km 2. The study database consisted of convective systems in West Africa from May Sep for 1998-2007 and in the western Pacific from May Nov 1998-2007. Annual cumulative frequency distributions for system minimum brightness temperature and system area were constructed for both regions. For both regions, there were no statistically significant differences among the annual curves for system minimum brightness temperature. There were two groups of system area curves, split by the TRMM altitude boost in 2001. Within each set, there was no statistically significant interannual variability. Sub-setting the database revealed some sensitivity in distribution shape to the size of the sampling area, length of sample period, and climate zone. From a regional perspective, the stability of the cumulative frequency distributions implied that the probability that a convective system would attain a particular size or intensity does not change interannually. Variability in the number of convective events appeared to be more important in determining whether a year is wetter or drier than normal.

  14. Interannual variability: a crucial component of space use at the territory level.

    PubMed

    Uboni, Alessia; Vucetich, John A; Stahler, Daniel R; Smith, Douglas W

    2015-01-01

    Interannual variability in space use and how that variation is influenced by density-dependent and density-independent factors are important processes in population ecology. Nevertheless, interannual variability has been neglected by the majority of space use studies. We assessed that variation for wolves living in 15 different packs within Yellowstone National Park during a 13-year period (1996-2008). We estimated utilization distributions to quantify the intensity of space use within each pack's territory each year in summer and winter. Then, we used the volume of intersection index (VI) to quantify the extent to which space use varied from year to year. This index accounts for both the area of overlap and differences in the intensity of use throughout a territory and ranges between 0 and 1. The mean VI index was 0.49, and varied considerably, with approximately 20% of observations (n = 230) being <0.3 or >0.7. In summer, 42% of the variation was attributable to differences between packs. These differences can be attributable to learned behaviors and had never been thought to have such an influence on space use. In winter, 34% of the variation in overlap between years was attributable to interannual differences in precipitation and pack size. This result reveals the strong influence of climate on predator space use and underlies the importance of understanding how climatic factors are going to affect predator populations in the occurrence of climate change. We did not find any significant association between overlap and variables representing density-dependent processes (elk and wolf densities) or intraspecific competition (ratio of wolves to elk). This last result poses a challenge to the classic view of predator-prey systems. On a small spatial scale, predator space use may be driven by factors other than prey distribution.

  15. Interannual Variability of Boreal Summer Rainfall in the Equatorial Atlantic

    NASA Technical Reports Server (NTRS)

    Gu, Guojun; Adler, Robert F.

    2007-01-01

    Tropical Atlantic rainfall patterns and variation during boreal summer [June-July-August (JJA)] are quantified by means of a 28-year (1979-2006) monthly precipitation dataset from the Global Precipitation Climatology Project (GPCP). Rainfall variability during boreal spring [March-April-May (MAM)] is also examined for comparison in that the most intense interannual variability is usually observed during this season. Comparable variabilities in the Intertropical Convergence Zone (ITCZ) strength and the basin-mean rainfall are found during both seasons. Interannual variations in the ITCZ's latitudinal location during JJA however are generally negligible, in contrasting to intense year-to-year fluctuations during MAM. Sea surface temperature (SST) oscillations along the equatorial region (usually called the Atlantic Nino events) and in the tropical north Atlantic (TNA) are shown to be the two major local factors modulating the tropical Atlantic climate during both seasons. During MAM, both SST modes tend to contribute to the formation of an evident interhemispheric SST gradient, thus inducing anomalous shifting of the ITCZ and then forcing a dipolar structure of rainfall anomalies across the equator primarily in the western basin. During JJA the impacts however are primarily on the ITCZ strength likely due to negligible changes in the ITCZ latitudinal location. The Atlantic Nino reaches its peak in JJA, while much weaker SST anomalies appear north of the equator in JJA than in MAM, showing decaying of the interhemispheric SST mode. SST anomalies in the tropical central-eastern Pacific (the El Nino events) have a strong impact on tropical Atlantic including both the tropical north Atlantic and the equatorial-southern Atlantic. However, anomalous warming in the tropical north Atlantic following positive SST anomalies in the tropical Pacific disappears during JJA because of seasonal changes in the large-scale circulation cutting off the ENSO influence passing through the

  16. Interannual sandbar variability within the Columbia River Littoral Cell

    NASA Astrophysics Data System (ADS)

    Ortiz, J. P.; Cohn, N.; Ruggiero, P.

    2013-12-01

    Examining nearshore sandbar behavior is highly relevant to understanding past and predicting future coastal change because of the role that these morphologic features play in regional sand budgets. However, because of the difficulty and expense of collecting nearshore bathymetric data, relatively few long-term data sets of sandbar morphology exist. At sites where sufficient data has been collected, a common phenomenon observed is a cyclic, multi-year offshore migration of sandbars. This cycle typically follows a general three-stage conceptual model of net offshore migration (NOM) originally proposed by Ruessink and Kroon (1994) whereby each individual bar is: (1) generated close to shore, (2) migrates seaward, and (3) decays at the outer margin of the nearshore zone. One such location where a clear NOM cycle has been observed is in the Columbia River Littoral Cell (CRLC).The CRLC is a high energy, dissipative coast located in northwest Oregon and southwest Washington which is characterized by fine sand and an intense wave climate. A beach morphology monitoring program that includes annual nearshore bathymetry surveys and quarterly subaerial beach topography measurements was initiated in 1997 (Ruggiero et al., 2005). Data from this long-term field effort indicates that there are large spatial and temporal differences in bar behavior throughout the littoral cell, but that in general there is a net offshore movement of the bars on interannual time scales. In this study, the high-resolution coastal profile data from the beach monitoring program are used to specifically evaluate bar dynamics along the Long Beach subcell of the CRLC. Parameters such as bar crest position from the shoreline, bar crest depth, and bar height have been extracted from the dataset and are being used to evaluate both spatial and temporal trends in bar morphology. Initial results indicate that NOM cycles have approximately three-year return periods in Long Beach. Further analysis will focus on

  17. Interannual variability of surface radiative fluxes and rainfall in the semi-arid Sahel

    NASA Astrophysics Data System (ADS)

    Guichard, F.; Grippa, M.; Kergoat, L.; Hiernaux, P.; Mougin, E.; Timouk, F.; Delbart, N.

    2009-04-01

    difference can reach up to 30 W.m-2 on average over the month of August. This difference in Rnet is not related to an enhancement of the incoming longwave flux, LWin actually fluctuates by less than 5 W.m-2. More rain in August is associated with less incoming shortwave radiation, with a difference of about 10W.m-2. At this monthly time scale, variations of Rnet are more largely explained by changes in surface properties. This involves the vegetation dynamics, which accounts for large interannual fluctuations of albedo (Samain et al., J. Geophys. Res. 2008, http://www.agu.org/pubs/crossref/2008/2007JD009174.shtml). However, the processes accounting for the interannual variability of the upwelling longwave flux, LWup, are found to be at least as important as albedo effects when accounting for changes in Rnet. LWup decreases sharply in response to the succession of rainfall events in this region where soil temperature reaches very high values in Spring. At larger time scale (June to September average), LWup and rainfall are also found to be strongly and consistently related. As the interannual variability of shortwave incoming and upwelling flux partly balance each other, the upwelling longwave flux LWup appears as a major driver of the interannual variability of Rnet. These results emphasize the strong couplings taking place in the Sahelian climate between surface radiation, energy fluxes and the water cycle. They point to the significance of a variety of processes, among which aerosols and vegetation-related processes cannot be neglected. Finally, they provide valuable guidance for models over an area where interactions among processes are complex and climate projections currently very uncertain.

  18. Dynamical evidence for causality between galactic cosmic rays and interannual variation in global temperature

    DOE PAGES

    Tsonis, Anastasios A.; Deyle, Ethan R.; May, Robert M.; ...

    2015-03-02

    As early as 1959, it was hypothesized that an indirect link between solar activity and climate could be mediated by mechanisms controlling the flux of galactic cosmic rays (CR). Although the connection between CR and climate remains controversial, a significant body of laboratory evidence has emerged at the European Organization for Nuclear Research and elsewhere, demonstrating the theoretical mechanism of this link. In this article, we present an analysis based on convergent cross mapping, which uses observational time series data to directly examine the causal link between CR and year-to-year changes in global temperature. Despite a gross correlation, we findmore » no measurable evidence of a causal effect linking CR to the overall 20th-century warming trend. Furthermore, on short interannual timescales, we find a significant, although modest, causal effect between CR and short-term, year-to-year variability in global temperature that is consistent with the presence of nonlinearities internal to the system. Thus, although CR do not contribute measurably to the 20th-century global warming trend, they do appear as a nontraditional forcing in the climate system on short interannual timescales.« less

  19. Links between tropical Pacific seasonal, interannual and orbital variability during the Holocene

    NASA Astrophysics Data System (ADS)

    Emile-Geay, J.; Cobb, K. M.; Carré, M.; Braconnot, P.; Leloup, J.; Zhou, Y.; Harrison, S. P.; Corrège, T.; McGregor, H. V.; Collins, M.; Driscoll, R.; Elliot, M.; Schneider, B.; Tudhope, A.

    2016-02-01

    The El Niño/Southern Oscillation (ENSO) is the leading mode of interannual climate variability. However, it is unclear how ENSO has responded to external forcing, particularly orbitally induced changes in the amplitude of the seasonal cycle during the Holocene. Here we present a reconstruction of seasonal and interannual surface conditions in the tropical Pacific Ocean from a network of high-resolution coral and mollusc records that span discrete intervals of the Holocene. We identify several intervals of reduced variance in the 2 to 7 yr ENSO band that are not in phase with orbital changes in equatorial insolation, with a notable 64% reduction between 5,000 and 3,000 years ago. We compare the reconstructed ENSO variance and seasonal cycle with that simulated by nine climate models that include orbital forcing, and find that the models do not capture the timing or amplitude of ENSO variability, nor the mid-Holocene increase in seasonality seen in the observations; moreover, a simulated inverse relationship between the amplitude of the seasonal cycle and ENSO-related variance in sea surface temperatures is not found in our reconstructions. We conclude that the tropical Pacific climate is highly variable and subject to millennial scale quiescent periods. These periods harbour no simple link to orbital forcing, and are not adequately simulated by the current generation of models.

  20. Dynamical evidence for causality between galactic cosmic rays and interannual variation in global temperature

    SciTech Connect

    Tsonis, Anastasios A.; Deyle, Ethan R.; May, Robert M.; Sugihara, George; Swanson, Kyle; Verbeten, Joshua D.; Wang, Geli

    2015-03-02

    As early as 1959, it was hypothesized that an indirect link between solar activity and climate could be mediated by mechanisms controlling the flux of galactic cosmic rays (CR). Although the connection between CR and climate remains controversial, a significant body of laboratory evidence has emerged at the European Organization for Nuclear Research and elsewhere, demonstrating the theoretical mechanism of this link. In this article, we present an analysis based on convergent cross mapping, which uses observational time series data to directly examine the causal link between CR and year-to-year changes in global temperature. Despite a gross correlation, we find no measurable evidence of a causal effect linking CR to the overall 20th-century warming trend. Furthermore, on short interannual timescales, we find a significant, although modest, causal effect between CR and short-term, year-to-year variability in global temperature that is consistent with the presence of nonlinearities internal to the system. Thus, although CR do not contribute measurably to the 20th-century global warming trend, they do appear as a nontraditional forcing in the climate system on short interannual timescales.

  1. Impacts of absorbing aerosols on interannual and intraseasonal variability of the South Asian monsoon

    NASA Astrophysics Data System (ADS)

    Lau, W. K. M.; Kim, K. M.; Shi, J. J.; Tao, W. K.

    2015-12-01

    Aerosol-monsoon interactions on the interannual and intraseasonal variability of the South Asian monsoon are investigated from observations and modeling. On interannual time scales, we found from observations, and confirm with coupled ocean-atmosphere climate modeling, that absorbing aerosols (mainly desert dust and BC), can significantly amplifying the ENSO impact on the Indian monsoon, through precipitation and circulation feedback induced by the EHP effect. On intraseasonal time scales, modeling studies with the high-resolution WRF regional climate model demonstrated that EHP combined with the semi-direct and microphysics effects, associated with enhanced desert dust transported from the Middle East deserts across the Arabian Sea to the Indian subcontinent, may alter the moisture transport pathways, suppress the development of monsoon depression over northeastern India, resulting in development of intense convective cells, and extreme heavy rain along the Himalayan foothills in central and northwestern India. The implications of these feedback processes on climate change in the South Asian monsoon region will be discussed.

  2. Improved Water and Energy Management Utilizing Seasonal to Interannual Hydroclimatic Forecasts

    NASA Astrophysics Data System (ADS)

    Arumugam, S.; Lall, U.

    2014-12-01

    Seasonal to interannual climate forecasts provide valuable information for improving water and energy management. Given that the climatic attributes over these time periods are typically expressed as probabilistic information, we propose an adaptive water and energy management framework that uses probabilistic inflow forecasts to allocate water for uses with pre-specified reliabilities. To ensure that the system needs are not compromised due to forecast uncertainty, we propose uncertainty reduction using model combination and based on a probabilistic constraint in meeting the target storage. The talk will present findings from recent studies from various basins that include (a) role of multimodel combination in reducing the uncertainty in allocation (b) relevant system characteristics that improve the utility of forecasts, (c) significance of streamflow forecasts in promoting interbasin transfers and (d) scope for developing power demand forecasts utilizing temperature forecasts. Potential for developing seasonal nutrient forecasts using climate forecasts for supporting water quality trading will also be presented. Findings and synthesis from the panel discussion from the recently concluded AGU chapman conference on "Seaonal to Interannual Hydroclimatic Forecasts and Water Management" will also be summarized.

  3. Interannual Variability of the Tropical Water Cycle: Capabilities in the TRMM Era and Challenges for GPM

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.

    2003-01-01

    Considerable uncertainty surrounds the issue of whether precipitation over the tropical oceans (30" NE) systematically changes with interannual sea-surface temperature (SST) anomalies that accompany El Nino (warm) and La Nina (cold) events. Although it is well documented that El Nino-Southern Oscillation (ENSO) events with marked SST changes over the tropical oceans, produce significant regional changes in precipitation, water vapor, and radiative fluxes in the tropics, we still cannot yet adequately quantify the associated net integrated changes to water and heat balance over the entire tropical oceanic or land sectors. Robertson et al., [2001 GRL] for example, showed that substantial disagreement exists among contemporary satellite estimates of interannual variations in tropical rainfall that are associated with SST changes. Berg et al., [2002 J. Climate] have documented the distinct differences between precipitation structure over the eastern and western Pacific ITCZ and noted how various satellite precipitation algorithms may respond quite differently to ENSO modulations of these precipitation regimes. Resolving this uncertainty is important since precipitation and latent heat release variations over land and ocean sectors are key components of the tropical heat balance in its most aggregated form. Rainfall estimates from the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) averaged over the tropical oceans have not solved this issue and, in fact, show marked differences with estimates from two TRMM Microwave Imager (TMI) passive microwave algorithms. In this paper we will focus on findings that uncertainties in microphysical assumptions necessitated by the single-frequency PR measurement pose difficulties for detecting climate-related precipitation signals. Recent work has shown that path-integrated attenuation derived from the effects of precipitation on the radar return from the ocean surface exhibits interannual variability that agrees

  4. Codominant water control on global interannual variability and trends in land surface phenology and greenness.

    PubMed

    Forkel, Matthias; Migliavacca, Mirco; Thonicke, Kirsten; Reichstein, Markus; Schaphoff, Sibyll; Weber, Ulrich; Carvalhais, Nuno

    2015-09-01

    Identifying the relative importance of climatic and other environmental controls on the interannual variability and trends in global land surface phenology and greenness is challenging. Firstly, quantifications of land surface phenology and greenness dynamics are impaired by differences between satellite data sets and phenology detection methods. Secondly, dynamic global vegetation models (DGVMs) that can be used to diagnose controls still reveal structural limitations and contrasting sensitivities to environmental drivers. Thus, we assessed the performance of a new developed phenology module within the LPJmL (Lund-Potsdam-Jena managed Lands) DGVM with a comprehensive ensemble of three satellite data sets of vegetation greenness and ten phenology detection methods, thereby thoroughly accounting for observational uncertainties. The improved and tested model allows us quantifying the relative importance of environmental controls on interannual variability and trends of land surface phenology and greenness at regional and global scales. We found that start of growing season interannual variability and trends are in addition to cold temperature mainly controlled by incoming radiation and water availability in temperate and boreal forests. Warming-induced prolongations of the growing season in high latitudes are dampened by a limited availability of light. For peak greenness, interannual variability and trends are dominantly controlled by water availability and land-use and land-cover change (LULCC) in all regions. Stronger greening trends in boreal forests of Siberia than in North America are associated with a stronger increase in water availability from melting permafrost soils. Our findings emphasize that in addition to cold temperatures, water availability is a codominant control for start of growing season and peak greenness trends at the global scale.

  5. Interannual Variability in Global Soil Respiration on a 0.5 Degree Grid Cell Basis (1980-1994)

    SciTech Connect

    Raich, J.W.

    2003-09-15

    We used a climate-driven regression model to develop spatially resolved estimates of soil-CO{sub 2} emissions from the terrestrial land surface for each month from January 1980 to December 1994, to evaluate the effects of interannual variations in climate on global soil-to-atmosphere CO{sub 2} fluxes. The mean annual global soil-CO{sub 2} flux over this 15-y period was estimated to be 80.4 (range 79.3-81.8) Pg C. Monthly variations in global soil-CO{sub 2} emissions followed closely the mean temperature cycle of the Northern Hemisphere. Globally, soil-CO{sub 2} emissions reached their minima in February and peaked in July and August. Tropical and subtropical evergreen broad-leaved forests contributed more soil-derived CO{sub 2} to the atmosphere than did any other vegetation type ({approx}30% of the total) and exhibited a biannual cycle in their emissions. Soil-CO{sub 2} emissions in other biomes exhibited a single annual cycle that paralleled the seasonal temperature cycle. Interannual variability in estimated global soil-CO{sub 2} production is substantially less than is variability in net carbon uptake by plants (i.e., net primary productivity). Thus, soils appear to buffer atmospheric CO{sub 2} concentrations against far more dramatic seasonal and interannual differences in plant growth. Within seasonally dry biomes (savannas, bushlands, and deserts), interannual variability in soil-CO{sub 2} emissions correlated significantly with interannual differences in precipitation. At the global scale, however, annual soil-CO{sub 2} fluxes correlated with mean annual temperature, with a slope of 3.3 PgCY{sup -1} per degree Celsius. Although the distribution of precipitation influences seasonal and spatial patterns of soil-CO{sub 2} emissions, global warming is likely to stimulate CO{sub 2} emissions from soils.

  6. Intraseasonal to interannual variability of summer monsoon rainfall and its influence on the Agricultural corps in mountainous Kashmir

    NASA Astrophysics Data System (ADS)

    Hussain, Z.; Saeed, S.

    2012-04-01

    By using high resolution APHRODITE precipitation and meteorological station data (1961-2007) the present study examines the intraseasonal to interannual variability of the monsoon rainfall over mountainous Kashmir and its influence on the agricultural crops such as Maiz and Wheat. It is found that an intraseasonal to interannual variability of the monsoon rainfall can severely affect the crop production in the hilly areas of Kashmir. We found an increasing trend in the extreme precipitation events over Kashmir and adjacent areas in the recent years. The associated crop production shows significant decreasing trend especially over the hilly areas in Kashmir. The enhanced rainfall can result in the soil erosion that impose a major threat to sustainable agriculture in the mountainous areas of Kashmir. The heavy rainfall associated with the orographic uplifitng removes the uppermost fertile layer of soil, depleting fertility and leaving the soil in poor physical condition. This further causes severe deficiency of most important nutrients required for plant growth and crop yield. We further analysed the IPCC AR4 ECHAM5/MPIOM climate model simulations to examine the future interannual variability of monsoon rainfall over Kashmir and adjoining areas. In the following we analysed the transient run with a 1% per year increase in CO2 until reaching double concentrations and held constant thereafter. We found enhanced interannual variability of the summer monsoon rainfall (July-August) with increasing drought like conditions over Kashmir and adjoining northern parts of Pakistan in future climate. The enhanced interannual variability of precipitation in future could further affect severely growth of various agricultural crops in mountainous parts of Kashmir.

  7. Interannual variability of Black Sea's hydrodynamics and connection to atmospheric patterns

    NASA Astrophysics Data System (ADS)

    Capet, Arthur; Barth, Alexander; Beckers, Jean-Marie; Marilaure, Grégoire

    2012-11-01

    The long term variability (1962-2000) of the Black Sea physical processes (e.g. temperature, main circulation, cold intermediate layer, sea level) and its relation to atmospheric conditions and large scale climate patterns are investigated using an eddy-resolving tridimensional model in combination with statistical tools (e.g. Empirical Orthogonal Functions, Self Organizing Maps). First, the ability of the model to represent the interannual dynamics of the system is assessed by comparing the modeled and satellite sea surface temperature (SST) and sea level anomaly (SLA) decomposed into their dominant Empirical Orthogonal Functions (EOFs). The correlation between the spatial and temporal EOFs modes derived from model and satellite data is usually satisfactory and this gives some confidence in using the model as a tool to investigate not only the SST and SLA dynamics but also the dynamics of connected variables. Then, the long term variability (1962-2000) of the Black Sea hydrodynamics is assessed by decomposing into their dominant EOFs modeled SST, SLA and selected key hydrodynamical variables associated to the main circulation and vertical structure of the water column. Significant correlations between the EOFs associated to these variables are investigated in order to link the variability of surface fields and the internal dynamics of the system. In particular, the intensity of the general cyclonic circulation (the Rim Current) is shown to impact strongly (1) the mean sea level, (2) the SST response to air temperature (AT), (3) the formation of the cold intermediate layer, (4) the meridional repartition of the SST anomaly and (5) the exchanges of heat between the north-western shelf and the open basin. In order to appraise the variability of atmospheric conditions over the Black Sea during 1962-2000 and their role in driving the hydrodynamics, a self-organizing maps technique is used to identify spatial recurrent patterns of atmospheric fields (i.e., AT, wind

  8. Projected Changes in Mean and Interannual Variability of Surface Water over Continental China

    SciTech Connect

    Leng, Guoyong; Tang, Qiuhong; Huang, Maoyi; Hong, Yang; Leung, Lai-Yung R.

    2015-05-09

    Five General Circulation Model (GCM) climate projections under the RCP8.5 emission scenario were used to drive the Variable Infiltration Capacity (VIC) hydrologic model to investigate the impacts of climate change on hydrologic cycle over continental China in the 21st century. The bias-corrected climatic variables were generated for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR5) by the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP). Results showed much larger fractional changes of annual mean Evaportranspiration (ET) per unit warming than the corresponding fractional changes of Precipitation (P) per unit warming across the country especially for South China, which led to notable decrease of surface water variability (P-E). Specifically, negative trends for annual mean runoff up to -0.33%/decade and soil moisture trends varying between -0.02 to -0.13%/decade were found for most river basins across China. Coincidentally, interannual variability for both runoff and soil moisture exhibited significant positive trends for almost all river basins across China, implying an increase in extremes relative to the mean conditions. Noticeably, the largest positive trends for runoff variability and soil moisture variability, which were up to 38 0.41%/decade and 0.90%/decade, both occurred in Southwest China. In addition to the regional contrast, intra-seasonal variation was also large for the runoff mean and runoff variability changes, but small for the soil moisture mean and variability changes. Our results suggest that future climate change could further exacerbate existing water-related risks (e.g. floods and droughts) across China as indicated by the marked decrease of surface water amounts combined with steady increase of interannual variability throughout the 21st century. This study highlights the regional contrast and intra-seasonal variations for the projected hydrologic changes and could provide muti

  9. Interannual variation and long-term trends in proportions of resident individuals in partially migratory birds.

    PubMed

    Meller, Kalle; Vähätalo, Anssi V; Hokkanen, Tatu; Rintala, Jukka; Piha, Markus; Lehikoinen, Aleksi

    2016-03-01

    Partial migration - a part of a population migrates and another part stays resident year-round on the breeding site - is probably the most common type of migration in the animal kingdom, yet it has only lately garnered more attention. Theoretical studies indicate that in partially migratory populations, the proportion of resident individuals (PoR) should increase in high latitudes in response to the warming climate, but empirical evidence exists for few species. We provide the first comprehensive overview of the environmental factors affecting PoR and the long-term trends in PoR by studying 27 common partially migratory bird species in Finland. The annual PoR values were calculated by dividing the winter bird abundance by the preceding breeding abundance. First, we analysed whether early-winter temperature, winter temperature year before or the abundance of tree seeds just before overwintering explains the interannual variation in PoR. Secondly, we analysed the trends in PoR between 1987 and 2011. Early-winter temperature explained the interannual variation in PoR in the waterbirds (waterfowl and gulls), most likely because the temperature affects the ice conditions and thereby the feeding opportunities for the waterbirds. In terrestrial species, the abundance of seeds was the best explanatory variable. Previous winter's temperature did not explain PoR in any species, and thus, we conclude that the variation in food availability caused the interannual variation in PoR. During the study period, PoR increased in waterbirds, but did not change in terrestrial birds. Partially migratory species living in physically contrasting habitats can differ in their annual and long-term population-level behavioural responses to warming climate, possibly because warm winter temperatures reduce ice cover and improve the feeding possibilities of waterbirds but do not directly regulate the food availability for terrestrial birds.

  10. Interannual Variability in Amundsen Sea Ice-Shelf Height Change Linked to ENSO

    NASA Astrophysics Data System (ADS)

    Paolo, F. S.; Fricker, H. A.; Padman, L.

    2015-12-01

    Atmospheric and sea-ice conditions around Antarctica, particularly in the Amundsen and Bellingshausen seas, respond to climate dynamics in the tropical Pacific Ocean on interannual time scales including the El Nino-Southern Oscillation (ENSO). It has been hypothesized that the mass balance of the Antarctic Ice Sheet, including its floating ice shelves, also responds to this climate signal; however, this has not yet been unambiguously demonstrated. We apply multivariate singular spectrum analysis (MSSA) to our 18-year (1994-2012) time series of ice-shelf height in the Amundsen Sea (AS) region. This advanced spectral method distinguishes between regular deterministic behavior ("cycles") at sub-decadal time scale and irregular behavior ("noise") at shorter time scales. Although the long-term trends of AS ice-shelf height changes are much larger than the range of interannual variability, the short-term rate of change dh/dt can vary about the trend by more than 50%. The mode of interannual variability in the AS ice-shelf height is strongly correlated with the low-frequency mode of ENSO (periodicity of ~4.5 years) as represented by the Southern Oscillation Index. The ice-shelf height in the AS is expected to respond to changes in precipitation and inflows of warm subsurface Circumpolar Deep Water (CDW) into the ocean cavities under the ice shelves, altering basal melt rates. Since both of these processes affecting ice-shelf mass balance respond to changes in wind fields for different ENSO states, we expect some correlation between them. We will describe the spatial structure of AS ice-shelf height response to ENSO, and attempt to distinguish the precipitation signal from basal mass balance due to changing CDW inflows.

  11. Interannual variability in aboveground tree growth in Stehekin River watershed, North Cascade Range, Washington

    USGS Publications Warehouse

    Hessl, Amy E.; Peterson, D.L.

    2004-01-01

    Many forests in the Pacific Northwest region of North America are both highly productive and sensitive to climate. The combination of productivity and sensitivity makes forests vulnerable to changes in future climate and most likely to feed back to the regional carbon cycle. We reconstructed basal area increment (BAI) for 20 yr using tree-ring increments and diameter to identify species-specific responses of 14 forested vegetation types in the Stehekin River watershed in the North Cascade Range, to interannual climatic variability. Mean basal area increment (MBAI) for the 20-yr period is low when the standard error is low, but as MBAI increases, the standard error (SE) is more variable. Growth at sites with both low SE and MBAI may be related to climatic variables, however, some forest types dominated by Douglas-fir and mountain hemlock are both productive and responsive to climatic variability. Many forests in the Pacific Northwest are dominated by Douglas-fir, a commercially important timber species, and as a result, may play a major role in the regional carbon balance. Douglas-fir and mountain hemlock forests in the eastern portion of the North Cascades should be carefully monitored and managed in the context of both changing climatic conditions and regional carbon budgets.

  12. Recurrent groin hernia

    PubMed Central

    Cox, P. J.; Leach, R. D.; Ellis, Harold

    1981-01-01

    One hundred consecutive recurrences following repair of inguinal hernias have been studied; 62 were direct, 30 indirect, 7 pantaloon and one a femoral hernia. Half the indirect recurrences occurred within a year of repair and probably represented failure to detect a small indirect sac. Later indirect recurrences probably represented failure to repair the internal ring. Nine of the direct hernias were medial funicular recurrences and represented failure to anchor the darn medially. The rest of the direct recurrences were attributable to tissue insufficiency and could probably have been averted by larger tissue bites. Recurrences following inguinal herniorrhaphy remain an all too common problem but can be reduced by meticulous surgical technique. PMID:7339602

  13. Modeling interannual variability of seasonal evaporation and storage change based on the extended Budyko framework

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Alimohammadi, Negin; Wang, Dingbao

    2013-09-01

    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 interannual 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 interannual 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. The 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.

  14. Interannual variability of Indian Ocean subtropical mode water subduction rate

    NASA Astrophysics Data System (ADS)

    Ma, Jie; Lan, Jian

    2016-08-01

    The interannual variation of Indian Ocean subtropical mode water (IOSTMW) subduction rate in the Southwest Indian Ocean from 1980 to 2007 is investigated in this paper based on Simple Ocean Data Assimilation (SODA) outputs. Climatology of subduction rate exceeds 75 m/year in the IOSTMW formation area. The renewal time of permanent pycnocline water mass based on the subduction rate is calculated for each density class: 3-6 years for IOSTMW (25.8 < σ θ < 26.2 kg m-3). Subduction rate in the Southwest Indian Ocean subtropical gyre exhibits a great year-to-year variability. This interannual variations of the IOSTMW subduction rate is primarily dominated by the lateral induction term, associated with the interannual variations of strong meridional gradient of winter mixed layer depth (MLD). The slope of the mixed layer depth in the mode water is closely linked to the large variations of deep late winter MLD in the mid-latitudes and negligible variations of shallow winter MLD in lower latitudes. It is further identified that the interannual variation of late winter MLD in this area is largely controlled by the latent and sensible heat flux components. The water volume of the permanent pycnocline in the IOSTMW distribution area is also found to show a significant interannual variability, and it is well correlated with the interannual variation of subduction rate.

  15. Interannual variations and trends in global land surface phenology derived from enhanced vegetation index during 1982-2010

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyang; Tan, Bin; Yu, Yunyue

    2014-05-01

    Land surface phenology is widely retrieved from satellite observations at regional and global scales, and its long-term record has been demonstrated to be a valuable tool for reconstructing past climate variations, monitoring the dynamics of terrestrial ecosystems in response to climate impacts, and predicting biological responses to future climate scenarios. This study detected global land surface phenology from the advanced very high resolution radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) data from 1982 to 2010. Based on daily enhanced vegetation index at a spatial resolution of 0.05 degrees, we simulated the seasonal vegetative trajectory for each individual pixel using piecewise logistic models, which was then used to detect the onset of greenness increase (OGI) and the length of vegetation growing season (GSL). Further, both overall interannual variations and pixel-based trends were examined across Koeppen's climate regions for the periods of 1982-1999 and 2000-2010, respectively. The results show that OGI and GSL varied considerably during 1982-2010 across the globe. Generally, the interannual variation could be more than a month in precipitation-controlled tropical and dry climates while it was mainly less than 15 days in temperature-controlled temperate, cold, and polar climates. OGI, overall, shifted early, and GSL was prolonged from 1982 to 2010 in most climate regions in North America and Asia while the consistently significant trends only occurred in cold climate and polar climate in North America. The overall trends in Europe were generally insignificant. Over South America, late OGI was consistent (particularly from 1982 to 1999) while either positive or negative GSL trends in a climate region were mostly reversed between the periods of 1982-1999 and 2000-2010. In the Northern Hemisphere of Africa, OGI trends were mostly insignificant, but prolonged GSL was evident over individual climate regions during the last 3

  16. How accurately do we know interannual variations of surface mass balance and firn volume in Antarctica?

    NASA Astrophysics Data System (ADS)

    Horwath, Martin; van den Broeke, Michiel R.; Lenaerts, Jan T. M.; Ligtenberg, Stefan R. M.; Legrésy, Benoît; Blarel, Fabien

    2013-04-01

    Knowing the interannual variations in the Antarctic ice sheet net snow accumulation, or surface mass balance (SMB), is essential for analyzing and interpreting present-day observations. For example, accumulation events like the one in East Antarctica in 2009 (Shepherd et al. 2012, Science, doi: 10.1126/science.1228102) challenge our ability to interpret observed decadal-scale trends in terms of long-term changes versus natural fluctuations. SMB variations cause changes in the firn density structure, which need to be accounted for when converting volume trends from satellite altimetry into mass trends. Recent assessments of SMB and firn volume variations mainly rely on atmospheric modeling and firn densification modeling (FDM). The modeling results need observational validation, which has been limited by now. Geodetic observations by satellite altimetry and satellite gravimetry reflect interannual firn volume and mass changes, among other signals like changes in ice flow dynamics. Therefore, these observations provide a means of validating modeling results over the observational period. We present comprehensive comparisons between interannual volume variations from ENVISAT radar altimetry (RA) and firn densification modeling (FDM), and between interannual mass variations from SMB modeling by the regional atmospheric climate model RACMO2 and GRACE satellite gravimetry. The comparisons are performed based on time series with approximately monthly sampling and with the overlapping period from 2002 to 2010. The RA-FDM comparison spans the spatial scales from 27 km to the continental scale. The mass comparison refers to the regional (drainage basin) and continental scale. Overall, we find good agreement between the interannual variations described by the models and by the geodetic observations. This agreement proves our ability to track and understand SMB-related ice sheet variations from year to year. The assessment of differences between modeling and observations

  17. Interannual and interdecadal variability in 335 years of central England temperatures

    SciTech Connect

    Plaut, G.; Ghil, M.; Vautard, R.

    1995-05-05

    Understanding the natural variability of climate is important for predicting its near-term evolution. Models of the oceans` thermohaline and wind-driven circulation show low-frequency oscillations. Long instrumental records can help validate the oscillatory behavior of these models. Singular spectrum analysis applied to the 335-year-long central England temperature (CET) record has identified climate oscillations with interannual (7- to 8-year) and interdecadal (15- and 25-year) periods, probably related to the North Atlantic`s wind-driven and thermohaline circulation, respectively. Statistical prediction of oscillatory variability shows CETs decreasing toward the end of this decade and rising again into the middle of the next. 42 refs., 4 figs.

  18. Climatic Versus Biotic Constraints on Carbon and Water Fluxes in Seasonally Drought-affected Ponderosa Pine Ecosystems. Chapter 2

    NASA Technical Reports Server (NTRS)

    Schwarz, P. A.; Law, B. E.; Williams, M.; Irvine, J.; Kurpius, M.; Moore, D.

    2005-01-01

    We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.

  19. Climatic versus biotic constraints on carbon and water fluxes in seasonally drought-affected ponderosa pine ecosystems

    NASA Astrophysics Data System (ADS)

    Schwarz, P. A.; Law, B. E.; Williams, M.; Irvine, J.; Kurpius, M.; Moore, D.

    2004-12-01

    We investigated the relative importance of climatic versus biotic controls on gross primary production (GPP) and water vapor fluxes in seasonally drought-affected ponderosa pine forests. The study was conducted in young (YS), mature (MS), and old stands (OS) over 4 years at the AmeriFlux Metolius sites. Model simulations showed that interannual variation of GPP did not follow the same trends as precipitation, and effects of climatic variation were smallest at the OS (<10%), largest at the MS (>50%), and intermediate at the YS (<20%). In the young, developing stand, interannual variation in leaf area has larger effects on fluxes than climate, although leaf area is a function of climate in that climate can interact with age-related shifts in carbon allocation and affect whole-tree hydraulic conductance. Older forests, with well-established root systems, appear to be better buffered from effects of seasonal drought and interannual climatic variation. Interannual variation of net ecosystem exchange (NEE) was also lowest at the OS, where NEE is controlled more by interannual variation of ecosystem respiration, 70% of which is from soil, than by the variation of GPP, whereas variation in GPP is the primary reason for interannual changes in NEE at the YS and MS. Across spatially heterogeneous landscapes with high frequency of younger stands resulting from natural and anthropogenic disturbances, interannual climatic variation and change in leaf area are likely to result in large interannual variation in GPP and NEE.

  20. Recurrent aphthous stomatitis.

    PubMed

    Chattopadhyay, Amit; Shetty, Kishore V

    2011-02-01

    Recurrent aphthous stomatitis is a common oral ulcerative disease, affecting 10% to 15% of the general US population. This article reviews the epidemiology and clinical presentations of recurrent aphthous stomatitis, including diagnosis and management.

  1. [Chronic recurrent multifocal osteomyelitis].

    PubMed

    Marrero Calvo, M; Merino Arribas, J; Rodrigo Palacios, J; Bartolomé Albistegui, M; Camino Fernández, A; Grande Sáez, C

    2001-02-01

    Chronic recurrent multifocal osteomyelitis is a rare disorder of unknown etiology, characterized by multiple bone lesions and a variable clinical course. We present a 10 year old boy with chronic recurrent multifocal osteomyelitis who improved after treatment with naproxen.

  2. The seasonal cycle revisited: interannual variation and ecosystem consequences

    NASA Astrophysics Data System (ADS)

    Bertram, Douglas F.; Mackas, David L.; McKinnell, Stewart M.

    The annual seasonal cycle accounts for much of the total temporal variability of mid- and high-latitude marine ecosystems. Although the general pattern of the seasons repeats each year, climatic variability of the atmosphere and the ocean produce detectable changes in intensity and onset timing. We use a combination of time series data from oceanographic, zooplankton and seabird breeding data to ask if and how these variations in the timing of the spring growing season affect marine populations. For the physical environment, we develop an annual index of spring timing by fitting a non-linear 2-parameter periodic function to the average weekly SST data observed in British Columbia from 1 January to the end of August each year. For each year, the phase parameter describes the timing of seasonal warming (the timing index) and the amplitude parameter describes the magnitude of the temperature increase between the fitted winter minimum and summer maximum. For the zooplankton, which have annual and strongly synchronous cycles of biomass, productivity, and developmental sequence, we use copepodite stage composition to index the timing of the annual maximum. For seabirds, we examine (1975-1999) the timing of hatching, nestling growth performance, and diet for four species of alcids at Triangle Island, British Columbia's largest seabird colony and the world's largest population of the planktivorous Cassin's auklet. Temperature, zooplankton, and seabirds have all shown recent decadal trends toward ‘earlier spring’, but the magnitudes of the timing perturbations have differed from variable to variable and from year to year. Recent (1996-1999) extreme interannual variation in spring timing and April SST helped to facilitate a mechanistic investigation of oceanographic features that affect the reproductive performance of seabirds. Our results demonstrate a significant negative relationship between the annual spring timing index (and April mean SST) and nestling growth rates

  3. Streamflow forecasts on seasonal and interannual time scales for reservoir management

    NASA Astrophysics Data System (ADS)

    Robertson, A. W.; Lu, M.; Lall, U.

    2014-12-01

    Seasonal climate forecasts are beginning to be complemented by improved forecasting capabilities at both sub-seasonal and interannual annual timescales, with the future prospect of seamless climate forecasts for water system operations. While seasonal predictability is often very limited by physical and modeling constraints, harnessing additional predictable components of the climate system may in some cases substantially increase their usable information content, and provide more flexible forecasts in terms of the kinds of management decisions that can be informed. Here we present an example of combining season and year-ahead streamflow forecasts as input to a multi-use reservoir optimization model, applied to the Bhakra Dam in NW India. Bi-timescale forecasts are made with a seasonal periodic autoregressive (PAR) model with exogenous climate-forecast inputs, together with an annual PAR model fit to observed flows used as a baseline for year-ahead forecasts. Annual net revenue from irrigation and hydropower supplies are calculated with contracts optimized using the reservoir optimization model. With Bhakra Dam inflows deriving from both winter storms/snow melt and the summer monsoon, it is found that net annual revenue is maximized when new contracts are initiated in March and June. We explore various choices of PARX model seasonal predictors based on climate model output and data and show that, with the choice of a good start date, even forecasts with relatively low skill can have value.

  4. Technical Report Series on Global Modeling and Data Assimilation. Volume 13; Interannual Variability and Potential Predictability in Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Min, Wei; Schubert, Siegfried D.; Suarez, Max J. (Editor)

    1997-01-01

    The Data Assimilation Office (DAO) at Goddard Space Flight Center and the National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR) have produced multi-year global assimilations of historical data employing fixed analysis systems. These "reanalysis" products are ideally suited for studying short-term climatic variations. The availability of multiple reanalysis products also provides the opportunity to examine the uncertainty in the reanalysis data. The purpose of this document is to provide an updated estimate of seasonal and interannual variability based on the DAO and NCEP/NCAR reanalyses for the 15-year period 1980-1995. Intercomparisons of the seasonal means and their interannual variations are presented for a variety of prognostic and diagnostic fields. In addition, atmospheric potential predictability is re-examined employing selected DAO reanalysis variables.

  5. Seasonal and interannual variations in the nitrogen cycle in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Rixen, T.; Baum, A.; Gaye, B.; Nagel, B.

    2014-10-01

    The Arabian Sea plays an important role in the marine nitrogen cycle because of its pronounced mid-water oxygen minimum zone (OMZ) in which bio-available nitrate (NO3-) is reduced to dinitrogen gas (N2). As the nitrogen cycle can respond fast to climate-induced changes in productivity and circulation, the Arabian Sea sediments are an important palaeoclimatic archive. In order to understand seasonal and interannual variations in the nitrogen cycle, nutrient data were obtained from the literature published prior to 1993, evaluated, and compared with data measured during five expeditions carried out in the framework of the Joint Global Ocean Flux Study (JGOFS) in the Arabian Sea in 1995 and during a research cruise of RV Meteor in 2007. The data comparison showed that the area characterized by a pronounced secondary nitrite maximum (SNM) was by 63% larger in 1995 than a similarly determined estimate based on pre-JGOFS data. This area, referred to as the core of the denitrifying zone, showed strong seasonal and interannual variations driven by the monsoon. During the SW monsoon, the SNM retreated eastward due to the inflow of oxygen-enriched Indian Ocean Central Water (ICW). During the NE monsoon, the SNM expanded westward because of the reversal of the current regime. On an interannual timescale, a weaker SW monsoon decreased the inflow of ICW from the equatorial Indian Ocean and increased the accumulation of denitrification tracers by extending the residence time of water in the SNM. This is supported by palaeoclimatic studies showing an enhanced preservation of accumulative denitrification tracers in marine sediments in conjunction with a weakening of the SW monsoon during the late Holocene.

  6. Seasonal and interannual variations of the nitrogen cycle in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Rixen, T.; Baum, A.; Gaye, B.; Nagel, B.

    2013-12-01

    The Arabian Sea is strongly influenced by the Asian monsoon and plays an important role as a climate archive and in the marine nitrogen cycle, because bio-available NO3- is reduced to dinitrogen gas (N2) in its mid-water oxygen minimum layer (OMZ). In order to investigate seasonal and interannual variations of the nitrogen cycle, nutrient data were obtained from the literature prior to 1993, evaluated, and compared with data measured during five expeditions in 1995 as well as a research cruise in 2007. Our results imply that the area characterized by a pronounced secondary nitrite maximum (SNM) was by 63% larger in 1995 than before. This area, referred to as the core of the denitrifying zone, shows strong seasonal and interannual variations driven by the monsoon. During the SW monsoon the SNM retreats eastwards due to the inflow of oxygen-enriched Indian Ocean Central Water (ICW) and it expands westwards during the NE monsoon because of the reversal of the current regime, which allows the propagation of denitrification signals from the Indian shelf into the open Arabian Sea. On an interannual time-scale an enhanced SW monsoon increases NO3- losses by increasing the upwelling-driven carbon export into the subsurface waters. An associate enhanced inflow of ICW increases the transport of denitrification signals from the SNM into the upwelling region and compensates NO3- losses by enhanced NO3- supply from the Indian Ocean. The latter sustains an enhanced productivity, which in turn transfers denitrification signals into the sedimentary records. On glacial interglacial time scales sea level changes affecting the inflow of ICW seem to increase variations in the accumulation of denitrification tracers in the SNM by reducing the residence time during glacial periods.

  7. Seasonal and interannual variability of the eastern boundary circulation and hydrography off Angola

    NASA Astrophysics Data System (ADS)

    Tchipalanga, Pedro; Macuéria, Marissa; Dengler, Marcus; Ostrowski, Marek; Kopte, Robert; Brandt, Peter

    2016-04-01

    Coastal countries of southwest Africa strongly depend upon their ocean: societal development, fisheries, and tourism face important changes associated with climate variability and global change. As an example, Angolan fisheries are currently reporting reduced catches that may be associated to variability of the eastern boundary circulation and water masses along the Angolan continental margin. In an effort to enhance understanding of the seasonal and interannual variability of the boundary circulation and thermocline water masses and their relation to warm and cold events in South East Atlantic, existing in-situ observations from a multi-cruise program were analyzed. Repeated hydrography and ship-board ADCP measurements from the EAF - Nansen Project collected during the Austral summer and winter period between 1995 and 2014 are used. From the ship-board velocity measurements, the average eastern boundary circulation at 6°S, 9°S, 12°S, 15°S and 17°S is presented for the summer and winter period. CTD data collected during the 24 cruises along the Angolan continental margin exhibit elevated interannual variability of heat and salt content in the upper thermocline between 50 and 150m depth. Warm and cold anomalies in the upper thermocline are strongly correlated to the Angola-Benguela area index and precede the respective sea surface temperature signal. The known warm events in 2001 and 2011 are well represented in the subsurface data. This suggests that thermocline heat anomalies serve as a preconditioning for the occurrences of Benguela Niños/Niñas. The processes responsible for the interannual variability of thermocline heat and salt contend are discussed.

  8. The Interannual Stability of Cumulative Frequency Distributions for Convective System Size and Intensity

    NASA Technical Reports Server (NTRS)

    Mohr, Karen I.; Molinari, John; Thorncroft, Chris

    2009-01-01

    The characteristics of convective system populations in West Africa and the western Pacific tropical cyclone basin were analyzed to investigate whether interannual variability in convective activity in tropical continental and oceanic environments is driven by variations in the number of events during the wet season or by favoring large and/or intense convective systems. Convective systems were defined from Tropical Rainfall Measuring Mission (TRMM) data as a cluster of pixels with an 85-GHz polarization-corrected brightness temperature below 255 K and with an area of at least 64 square kilometers. The study database consisted of convective systems in West Africa from May to September 1998-2007, and in the western Pacific from May to November 1998-2007. Annual cumulative frequency distributions for system minimum brightness temperature and system area were constructed for both regions. For both regions, there were no statistically significant differences between the annual curves for system minimum brightness temperature. There were two groups of system area curves, split by the TRMM altitude boost in 2001. Within each set, there was no statistically significant interannual variability. Subsetting the database revealed some sensitivity in distribution shape to the size of the sampling area, the length of the sample period, and the climate zone. From a regional perspective, the stability of the cumulative frequency distributions implied that the probability that a convective system would attain a particular size or intensity does not change interannually. Variability in the number of convective events appeared to be more important in determining whether a year is either wetter or drier than normal.

  9. Cold Regime Interannual Variability of Primary and Secondary Producer Community Composition in the Southeastern Bering Sea

    PubMed Central

    Stauffer, Beth A.; Miksis-Olds, Jennifer; Goes, Joaquim I.

    2015-01-01

    Variability of hydrographic conditions and primary and secondary productivity between cold and warm climatic regimes in the Bering Sea has been the subject of much study in recent years, while interannual variability within a single regime and across multiple trophic levels has been less well-documented. Measurements from an instrumented mooring on the southeastern shelf of the Bering Sea were analyzed for the spring-to-summer transitions within the cold regime years of 2009–2012 to investigate the interannual variability of hydrographic conditions, primary producer biomass, and acoustically-derived secondary producer and consumer abundance and community structure. Hydrographic conditions in 2012 were significantly different than in 2009, 2010, and 2011, driven largely by increased ice extent and thickness, later ice retreat, and earlier stratification of the water column. Primary producer biomass was more tightly coupled to hydrographic conditions in 2012 than in 2009 or 2011, and shallow and mid-column phytoplankton blooms tended to occur independent of one another. There was a high degree of variability in the relationships between different classes of secondary producers and hydrographic conditions, evidence of significant intra-consumer interactions, and trade-offs between different consumer size classes in each year. Phytoplankton blooms stimulated different populations of secondary producers in each year, and summer consumer populations appeared to determine dominant populations in the subsequent spring. Overall, primary producers and secondary producers were more tightly coupled to each other and to hydrographic conditions in the coldest year compared to the warmer years. The highly variable nature of the interactions between the atmospherically-driven hydrographic environment, primary and secondary producers, and within food webs underscores the need to revisit how climatic regimes within the Bering Sea are defined and predicted to function given

  10. 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.

  11. Variability of fire emissions on interannual to multi-decadal timescales in two Earth System models

    NASA Astrophysics Data System (ADS)

    Ward, D. S.; Shevliakova, E.; Malyshev, S.; Lamarque, J.-F.; Wittenberg, A. T.

    2016-12-01

    Connections between wildfires and modes of variability in climate are sought as a means for predicting fire activity on interannual to multi-decadal timescales. Several fire drivers, such as temperature and local drought index, have been shown to vary on these timescales, and analysis of tree-ring data suggests covariance between fires and climate oscillation indices in some regions. However, the shortness of the satellite record of global fire events limits investigations on larger spatial scales. Here we explore the interplay between climate variability and wildfire emissions with the preindustrial long control numerical experiments and historical ensembles of CESM1 and the NOAA/GFDL ESM2Mb. We find that interannual variability in fires is underpredicted in both Earth System models (ESMs) compared to present day fire emission inventories. Modeled fire emissions respond to the El Niño/southern oscillation (ENSO) and Pacific decadal oscillation (PDO) with increases in southeast Asia and boreal North America emissions, and decreases in southern North America and Sahel emissions, during the ENSO warm phase in both ESMs, and the PDO warm phase in CESM1. Additionally, CESM1 produces decreases in boreal northern hemisphere fire emissions for the warm phase of the Atlantic Meridional Oscillation. Through analysis of the long control simulations, we show that the 20th century trends in both ESMs are statistically significant, meaning that the signal of anthropogenic activity on fire emissions over this time period is detectable above the annual to decadal timescale noise. However, the trends simulated by the two ESMs are of opposite sign (CESM1 decreasing, ESM2Mb increasing), highlighting the need for improved understanding, proxy observations, and modeling to resolve this discrepancy.

  12. Dynamical evidence for causality between galactic cosmic rays and interannual variation in global temperature.

    PubMed

    Tsonis, Anastasios A; Deyle, Ethan R; May, Robert M; Sugihara, George; Swanson, Kyle; Verbeten, Joshua D; Wang, Geli

    2015-03-17

    As early as 1959, it was hypothesized that an indirect link between solar activity and climate could be mediated by mechanisms controlling the flux of galactic cosmic rays (CR) [Ney ER (1959) Nature 183:451-452]. Although the connection between CR and climate remains controversial, a significant body of laboratory evidence has emerged at the European Organization for Nuclear Research [Duplissy J, et al. (2010) Atmos Chem Phys 10:1635-1647; Kirkby J, et al. (2011) Nature 476(7361):429-433] and elsewhere [Svensmark H, Pedersen JOP, Marsh ND, Enghoff MB, Uggerhøj UI (2007) Proc R Soc A 463:385-396; Enghoff MB, Pedersen JOP, Uggerhoj UI, Paling SM, Svensmark H (2011) Geophys Res Lett 38:L09805], demonstrating the theoretical mechanism of this link. In this article, we present an analysis based on convergent cross mapping, which uses observational time series data to directly examine the causal link between CR and year-to-year changes in global temperature. Despite a gross correlation, we find no measurable evidence of a causal effect linking CR to the overall 20th-century warming trend. However, on short interannual timescales, we find a significant, although modest, causal effect between CR and short-term, year-to-year variability in global temperature that is consistent with the presence of nonlinearities internal to the system. Thus, although CR do not contribute measurably to the 20th-century global warming trend, they do appear as a nontraditional forcing in the climate system on short interannual timescales.

  13. Determination of Arctic sea ice variability modes on interannual timescales via nonhierarchical clustering

    NASA Astrophysics Data System (ADS)

    Fučkar, Neven-Stjepan; Guemas, Virginie; Massonnet, François; Doblas-Reyes, Francisco

    2015-04-01

    Over the modern observational era, the northern hemisphere sea ice concentration, age and thickness have experienced a sharp long-term decline superimposed with strong internal variability. Hence, there is a crucial need to identify robust patterns of Arctic sea ice variability on interannual timescales and disentangle them from the long-term trend in noisy datasets. The principal component analysis (PCA) is a versatile and broadly used method for the study of climate variability. However, the PCA has several limiting aspects because it assumes that all modes of variability have symmetry between positive and negative phases, and suppresses nonlinearities by using a linear covariance matrix. Clustering methods offer an alternative set of dimension reduction tools that are more robust and capable of taking into account possible nonlinear characteristics of a climate field. Cluster analysis aggregates data into groups or clusters based on their distance, to simultaneously minimize the distance between data points in a given cluster and maximize the distance between the centers of the clusters. We extract modes of Arctic interannual sea-ice variability with nonhierarchical K-means cluster analysis and investigate the mechanisms leading to these modes. Our focus is on the sea ice thickness (SIT) as the base variable for clustering because SIT holds most of the climate memory for variability and predictability on interannual timescales. We primarily use global reconstructions of sea ice fields with a state-of-the-art ocean-sea-ice model, but we also verify the robustness of determined clusters in other Arctic sea ice datasets. Applied cluster analysis over the 1958-2013 period shows that the optimal number of detrended SIT clusters is K=3. Determined SIT cluster patterns and their time series of occurrence are rather similar between different seasons and months. Two opposite thermodynamic modes are characterized with prevailing negative or positive SIT anomalies over the

  14. Sensitivity of Interannual Fluctuations of the Marine Ecoystem to Changes in the Ocean Circulation.

    NASA Astrophysics Data System (ADS)

    Winguth, A. M.; Maier-Reimer, E.; Dobbel, M.

    2002-12-01

    Factors controlling the interannual distribution of phytoplankton or zooplankton are largely unknown and thus resulting in large uncertainties in the prediction of sources and sinks of CO2 in the ocean. We are using two coupled ocean general circulation - marine ecosystem models with different resolution, the NPZD-type HAMOCC4 coupled to the LSG and the C-HOPE, to explore how different physical resolutions and parameterizations can explain some of the agreements and discrepancies between the data and the model. In addition, sensitivity experiments by variation of the ecosystem parameters and by including an empirical chlorophyll-to-carbon ratio have been carried out to study and discuss potential causes of the model-data differences between the observed and simulated chlorophyll concentrations. These sensitivity experiments are designed to be a first step towards a currently developed inverse ecosystem model to quantify large-scale interannual-to-decadal fluctuations of the marine carbon cycle and to provide more accurate predictions of the climate system.

  15. Interannual variability of H218O in precipitation over the Asian monsoon region

    NASA Astrophysics Data System (ADS)

    Ishizaki, Yasuhiro; Yoshimura, Kei; Kanae, Shinjiro; Kimoto, Masahide; Kurita, Naoyuki; Oki, Taikan

    2012-08-01

    The stable isotopic composition of water has been used as a paleoproxy to reconstruct past climates over the Asian monsoon region, but the main controls on the variability of isotopes of water in precipitation have not been characterized quantitatively in this region. Therefore, we used an atmospheric general circulation model incorporating stable water isotope physics to quantitatively estimate the relative contributions to isotope variability in precipitation falling in the Asian monsoon region. As in previous research, we identified two primary factors controlling the interannual variability of δ18Oprecip (defined as (Rsample/RVSMOW - 1) × 1000, where RVSMOW is the 18O ratio in Vienna Standard Mean Ocean Water) and its correlation with El Niño-Southern Oscillation (ENSO) events: the amount of precipitation at the observation site, and distillation during transport from source regions. Two sensitivity experiments revealed that distillation during transport from source regions was the dominant controlling factor; at Bangkok, Bombay, and Hong Kong, the amount of local precipitation contributed 27%, 33%, and 25% while distillation processes contributed 70%, 60%, and 70%, respectively. Similarly, distillation processes accounted for 80%, 82%, and 83% of observed differences in δ18Oprecip between El Niño and La Niña years at these three cities, respectively. Therefore, interannual variability of δ18Oprecipat the three stations primarily reflects distillation during transport from source regions, and it is also governed by the large-scale tropical variability (ENSO).

  16. Interannual differences for sea turtles bycatch in Spanish longliners from Western Mediterranean Sea.

    PubMed

    Báez, José C; Macías, David; García-Barcelona, Salvador; Real, Raimundo

    2014-01-01

    Recent studies showed that regional abundance of loggerhead and leatherback turtles could oscillate interannually according to oceanographic and climatic conditions. The Western Mediterranean is an important fishing area for the Spanish drifting longline fleet, which mainly targets swordfish, bluefin tuna, and albacore. Due to the spatial overlapping in fishing activity and turtle distribution, there is an increasing sea turtle conservation concern. The main goal of this study is to analyse the interannual bycatch of loggerhead and leatherback turtles by the Spanish Mediterranean longline fishery and to test the relationship between the total turtle by-catch of this fishery and the North Atlantic Oscillation (NAO). During the 14 years covered in this study, the number of sea turtle bycatches was 3,940 loggerhead turtles and 8 leatherback turtles, 0.499 loggerhead turtles/1000 hooks and 0.001014 leatherback turtles/1000 hooks. In the case of the loggerhead turtle the positive phase of the NAO favours an increase of loggerhead turtles in the Western Mediterranean Sea. However, in the case of leatherback turtle the negative phase of the NAO favours the presence of leatherback turtle. This contraposition could be related to the different ecophysiological response of both species during their migration cycle.

  17. Interannual Differences for Sea Turtles Bycatch in Spanish Longliners from Western Mediterranean Sea

    PubMed Central

    Báez, José C.; García-Barcelona, Salvador

    2014-01-01

    Recent studies showed that regional abundance of loggerhead and leatherback turtles could oscillate interannually according to oceanographic and climatic conditions. The Western Mediterranean is an important fishing area for the Spanish drifting longline fleet, which mainly targets swordfish, bluefin tuna, and albacore. Due to the spatial overlapping in fishing activity and turtle distribution, there is an increasing sea turtle conservation concern. The main goal of this study is to analyse the interannual bycatch of loggerhead and leatherback turtles by the Spanish Mediterranean longline fishery and to test the relationship between the total turtle by-catch of this fishery and the North Atlantic Oscillation (NAO). During the 14 years covered in this study, the number of sea turtle bycatches was 3,940 loggerhead turtles and 8 leatherback turtles, 0.499 loggerhead turtles/1000 hooks and 0.001014 leatherback turtles/1000 hooks. In the case of the loggerhead turtle the positive phase of the NAO favours an increase of loggerhead turtles in the Western Mediterranean Sea. However, in the case of leatherback turtle the negative phase of the NAO favours the presence of leatherback turtle. This contraposition could be related to the different ecophysiological response of both species during their migration cycle. PMID:24764769

  18. The relationships between temperature changes and reproductive investment in a Mediterranean goby: Insights for the assessment of climate change effects

    NASA Astrophysics Data System (ADS)

    Zucchetta, M.; Cipolato, G.; Pranovi, F.; Antonetti, P.; Torricelli, P.; Franzoi, P.; Malavasi, S.

    2012-04-01

    The relationships between changes in water temperature and the timing and level of reproductive investment were investigated in an estuarine fish, inhabiting the Venice lagoon: the grass goby Zosterisessor ophiocephalus. A time series of the mean monthly values of gonado-somatic index was coupled with thermal profiles of lagoon water temperatures over 14 years, from 1997 to 2010. Results showed that the reproductive investment was positively affected by water temperature changes, both in terms of monthly thermal anomalies and cumulative degree days. A predictive model was also developed to assess the temporal shift of reproductive peaks as a response to inter-annual thermal fluctuations. This model allowed the detection of deviations from the median level, indicating that during warmer years, the reproductive peak tended to occur earlier than during colder years. The model is therefore proposed as a tool to predict anticipated consequences of climate change on fish phenology in transitional waters, regarding recurrent biological phenomena, such as reproduction and recruitment.

  19. A multimodel approach to interannual and seasonal prediction of Danube discharge anomalies

    NASA Astrophysics Data System (ADS)

    Rimbu, Norel; Ionita, Monica; Patrut, Simona; Dima, Mihai

    2010-05-01

    Interannual and seasonal predictability of Danube river discharge is investigated using three model types: 1) time series models 2) linear regression models of discharge with large-scale climate mode indices and 3) models based on stable teleconnections. All models are calibrated using discharge and climatic data for the period 1901-1977 and validated for the period 1978-2008 . Various time series models, like autoregressive (AR), moving average (MA), autoregressive and moving average (ARMA) or singular spectrum analysis and autoregressive moving average (SSA+ARMA) models have been calibrated and their skills evaluated. The best results were obtained using SSA+ARMA models. SSA+ARMA models proved to have the highest forecast skill also for other European rivers (Gamiz-Fortis et al. 2008). Multiple linear regression models using large-scale climatic mode indices as predictors have a higher forecast skill than the time series models. The best predictors for Danube discharge are the North Atlantic Oscillation (NAO) and the East Atlantic/Western Russia patterns during winter and spring. Other patterns, like Polar/Eurasian or Tropical Northern Hemisphere (TNH) are good predictors for summer and autumn discharge. Based on stable teleconnection approach (Ionita et al. 2008) we construct prediction models through a combination of sea surface temperature (SST), temperature (T) and precipitation (PP) from the regions where discharge and SST, T and PP variations are stable correlated. Forecast skills of these models are higher than forecast skills of the time series and multiple regression models. The models calibrated and validated in our study can be used for operational prediction of interannual and seasonal Danube discharge anomalies. References Gamiz-Fortis, S., D. Pozo-Vazquez, R.M. Trigo, and Y. Castro-Diez, Quantifying the predictability of winter river flow in Iberia. Part I: intearannual predictability. J. Climate, 2484-2501, 2008. Gamiz-Fortis, S., D. Pozo

  20. Exploring Interannual Sandbar Behavior Along a High-Energy Dissipative Coast

    NASA Astrophysics Data System (ADS)

    Cohn, N.; Ruggiero, P.; Walstra, D.

    2012-12-01

    The Columbia River Littoral Cell (CRLC) in the Pacific Northwest is a modally dissipative coastline characterized by fine-grained sediment and high wave energy. Storms of magnitude are frequent in this region, with significant wave heights exceeding 10 m approximately once per year. Sandbars in the CRLC have been observed to follow the interannual pattern of net offshore migration (NOM) that has been observed at several other locations, with bars typically forming close to shore, migrating seaward, and ultimately degenerating offshore. Including playing a major role in local sand budgets, sandbars also influence circulation patterns and storm impact to the coast. Despite the importance of these geomorphic features to coastal environments much is still unknown concerning the dominant mechanics that drive interannual sandbar behavior. A recent, three-year model hindcast of bar evolution off the coast of the Netherlands (Noordwijk) indicated that bar response is most heavily influenced by two factors: the directionality of waves relative to the coastline and the depth of the bar crest below the water surface (D.J.R. Walstra, A.J.H.M. Reniers, R. Ranasinghe, J.A. Roelcink, and B.G. Ruessink, Coast Eng. 47:190-200, 2012). While other factors such as wave height, wave period, and tidal elevation were recognized as influencing bar morphology, overall they were determined to play a subordinate role in bar behavior. In order to test whether the conclusions from the Noordwijk study are generally valid, the same model (Unibest-TC) and approach will be applied to bathymetric data from the CRLC. Because the CRLC and Noordwijk have widely different physical characteristics (e.g., wave climate, sediment supply, beach slope, tidal range) the CRLC provides a sharply different environment for which to investigate interannual bar behavior. Annual nearshore bathymetric surveys in the CRLC have been completed for over a decade using personal watercraft outfitted with the Coastal

  1. 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

  2. Interannual variability in species composition explained as seasonally entrained chaos.

    PubMed

    Dakos, Vasilis; Benincà, Elisa; van Nes, Egbert H; Philippart, Catharina J M; Scheffer, Marten; Huisman, Jef

    2009-08-22

    The species composition of plankton, insect and annual plant communities may vary markedly from year to year. Such interannual variability is usually thought to be driven by year-to-year variation in weather conditions. Here we examine an alternative explanation. We studied the effects of regular seasonal forcing on a multi-species predator-prey model consisting of phytoplankton and zooplankton species. The model predicts that interannual variability in species composition can easily arise without interannual variability in external conditions. Seasonal forcing increased the probability of chaos in our model communities, but squeezed these irregular species dynamics within the seasonal cycle. As a result, the population dynamics had a peculiar character. Consistent with long-term time series of natural plankton communities, seasonal variation led to a distinct seasonal succession of species, yet the species composition varied from year to year in an irregular fashion. Our results suggest that interannual variability in species composition is an intrinsic property of multi-species communities in seasonal environments.

  3. Interannual variation of the Asian-Pacific oscillation

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Chen, Lin

    2017-03-01

    Previous studies have identified an Asian-Pacific Oscillation (APO) teleconnection pattern, which exhibits an out-of-phase relationship in the summer tropospheric temperature with warming over the Eurasia and cooling over the Northern Pacific and the Northern America, and vice versa. But the interannual variation of this teleconnection remains obscure. This study points out that interannual variation of the APO teleconnection is associated with the second empirical orthogonal function (EOF) mode of the northern-hemisphere upper tropospheric temperature during boreal summer, which accounts for 14% of the variance. A heat budget analysis is conducted for the Eurasian region and the North Pacific region respectively to reveal the cause of the zonal dipole mode temperature structure. For the Eurasia region, the warming is contributed by the adiabatic heating process due to downward vertical motion anomalies. For the Northern Pacific region, the temperature variation is mainly contributed by zonal advection associated with interannual zonal wind perturbation acting on the climatological temperature gradient. Composite analysis and numerical experiments with an atmospheric general circulation model (AGCM) shows the interannual zonal wind perturbation is related to the sea surface temperature anomalies over the equatorial eastern Pacific.

  4. Interannual Variation in Root Production in Grasslands Affected by Artificially Modified Amount of Rainfall

    PubMed Central

    Fiala, Karel; Tůma, Ivan; Holub, Petr

    2012-01-01

    The effect of different amounts of rainfall on the below-ground plant biomass was studied in three grassland ecosystems. Responses of the lowland (dry Festuca grassland), highland (wet Cirsium grassland), and mountain (Nardus grassland) grasslands were studied during five years (2006–2010). A field experiment based on rainout shelters and gravity irrigation simulated three climate scenarios: rainfall reduced by 50% (dry), rainfall increased by 50% (wet), and the natural rainfall of the current growing season (ambient). The interannual variation in root increment and total below-ground biomass reflected the experimentally manipulated amount of precipitation and also the amount of current rainfall of individual years. The effect of year on these below-ground parameters was found significant in all studied grasslands. In comparison with dry Festuca grassland, better adapted to drought, submontane wet Cirsium grassland was more sensitive to the different water inputs forming rather lower amount of below-ground plant matter at reduced precipitation. PMID:22629201

  5. Interannual variability of the global net radiation balance and its consequence on global energy transport

    NASA Technical Reports Server (NTRS)

    Smith, Eric A.; Sohn, B. J.

    1990-01-01

    Global cloudiness and radiation budget data from Nimbus 6 and 7 are used to investigate the role of cloud and surface radiative forcing and elements of the earth's general circulation. Although globally integrated cloud forcing is nearly zero, there are large regional imbalances and well regulated processes in the shortwave and longwave spectrum that control the meridional gradient structure of the net radiation balance and the factors modulating the east-west oriented North Africa-western Pacific energy transport dipole. The analysis demonstrates that clouds play a dual role in both the shortwave and longwave spectra in terms of tropical and midlatitude east-west gradients. The key result is that cloud forcing, although not always the principle regulator of interannual variability of the global climate, serves to reinforce the basic three-cell meridional circulation.

  6. Interannual variability of carbon cycle implied by a 2-d atmospheric transport model.

    PubMed

    Can, Li; Xu, Li; Shao, Min; Zhang, Ren-Jian

    2004-01-01

    A 2-dimensional atmospheric transport model is deployed in a simplified CO2 inverse study. Calculated carbon flux distribution for the interval from 1981 to 1997 confirms the existence of a terrestrial carbon sink in mid-high latitude area of North Hemisphere. Strong interannual variability exists in carbon flux patterns, implying a possible link with ENSO and other natural episodes such as Pinatubo volcano eruption in 1991. Mechanism of this possible link was investigated with statistic method. Correlation analysis indicated that in North Hemisphere, climatic factors such as temperature and precipitation, to some extend, could influence the carbon cycle process of land and ocean, thus cause considerable change in carbon flux distribution. In addition, correlation study also demonstrated the possible, important role of Asian terrestrial ecosystems in carbon cycle.

  7. Trace gas variability within the Asian monsoon anticyclone on intraseasonal and interannual timescales

    NASA Astrophysics Data System (ADS)

    Nützel, Matthias; Dameris, Martin; Fierli, Federico; Stiller, Gabriele; Garny, Hella; Jöckel, Patrick

    2016-04-01

    The Asian monsoon and the associated monsoon anticyclone have the potential of substantially influencing the composition of the UTLS (upper troposphere/lower stratosphere) and hence global climate. Here we study the variability of the Asian summer monsoon anticyclone in the UTLS on intraseasonal and interannual timescales using results from long term simulations performed with the CCM EMAC (ECHAM5/MESSy Atmospheric Chemistry). In particular, we focus on specified dynamics simulations (Newtonian relaxation to ERA-Interim data) covering the period 1980-2013, which have been performed within the ESCiMo (Earth System Chemistry integrated Modelling) project (Jöckel et al., GMDD, 2015). Our main focus lies on variability of the anticyclone's strength (in terms of potential vorticity, geopotential and circulation) and variability in trace gas signatures (O3, H2O) within the anticyclone. To support our findings, we also include observations from satellites (MIPAS, MLS). Our work is linked to the EU StratoClim campaign in 2016.

  8. Interannual variation in root production in grasslands affected by artificially modified amount of rainfall.

    PubMed

    Fiala, Karel; Tůma, Ivan; Holub, Petr

    2012-01-01

    The effect of different amounts of rainfall on the below-ground plant biomass was studied in three grassland ecosystems. Responses of the lowland (dry Festuca grassland), highland (wet Cirsium grassland), and mountain (Nardus grassland) grasslands were studied during five years (2006-2010). A field experiment based on rainout shelters and gravity irrigation simulated three climate scenarios: rainfall reduced by 50% (dry), rainfall increased by 50% (wet), and the natural rainfall of the current growing season (ambient). The interannual variation in root increment and total below-ground biomass reflected the experimentally manipulated amount of precipitation and also the amount of current rainfall of individual years. The effect of year on these below-ground parameters was found significant in all studied grasslands. In comparison with dry Festuca grassland, better adapted to drought, submontane wet Cirsium grassland was more sensitive to the different water inputs forming rather lower amount of below-ground plant matter at reduced precipitation.

  9. On the predictability of the interannual behaviour of the Madden-Julian oscillation and its relationship with El Nino

    SciTech Connect

    Sperber, K.R., LLNL

    1998-03-01

    The Madden-Julian Oscillation (MJO) is the dominant mode of tropical variability at intraseasonal timescales. It displays substantial interannual variability in intensity which may have important implications for the predictability of the coupled system. The reasons for this interannual variability are not understood. The aim of this paper is to investigate whether the interannual behavior of the MJO is related to tropical sea surface temperature (SST) anomalies, particularly El Nino, and hence whether it is predictable. The interannual behavior of the MJO has been diagnosed initially in the 40-year NCEP/ NCAR Reanalysis. The results suggest that prior to the mid-1970s the activity of the MJO was consistently lower than during the latter part of the record. This may be related to either inadequacies in the data coverage, particularly over the tropical Indian Ocean prior to the introduction of satellite observations, or to the real effects of a decadal timescale warming in the tropical SSTs. The teleconnection patterns between interannual variations in MJO activity and SST show only a weak, barely significant, influence of El Nino in which the MJO is more active during the cold phase. As well as the NCEP/NCAR Reanalysis, a 4-member ensemble of 45 year integrations with the Hadley Centre climate model (HadAM2a), forced by observed SSTs for 1949-93, has been used to investigate the relationship between MJO activity and SST. HadAM2a is known to give a reasonable simulation of the MJO and the extended record provided by this ensemble of integrations allows a more robust investigation of the predictability of MJO activity than was possible with the 40-year NCEP/NCAR Reanalysis. The results have shown that, for the uncoupled system, with the atmosphere being driven by imposed SSTS, there is no reproducibility for the activity of the MJO from year to year. The interannual behavior of the MJO is not controlled by the phase of El Nino and would appear to be chaotic in

  10. Sensitivity of CFC-11 uptake to physical initial conditions and interannually varying surface forcing in a global ocean model

    NASA Astrophysics Data System (ADS)

    Danabasoglu, Gokhan; Peacock, Synte; Lindsay, Keith; Tsumune, Daisuke

    Sensitivity of the oceanic chlorofluorocarbon CFC-11 uptake to physical initial conditions and surface dynamical forcing (heat and salt fluxes and wind stress) is investigated in a global ocean model used in climate studies. Two different initial conditions are used: a solution following a short integration starting with observed temperature and salinity and zero velocities, and the quasi-equilibrium solution of an independent integration. For surface dynamical forcing, recently developed normal-year and interannually varying (1958-2000) data sets are used. The model CFC-11 global and basin inventories, particularly in the normal-year forcing case, are below the observed mean estimates, but they remain within the observational error bars. Column inventory spatial distributions indicate nontrivial differences due to both initial condition and forcing changes, particularly in the northern North Atlantic and Southern Ocean. These differences are larger between forcing sensitivity experiments than between the initial condition cases. The comparisons along the A16N and SR3 WOCE sections also show differences between cases. However, comparisons with observations do not clearly favor a particular case, and model-observation differences remain much larger than model-model differences for all simulations. The choice of initial condition does not significantly change the CFC-11 distributions. Both because of locally large differences between normal-year and interannually varying simulations and because the dynamical and CFC-11 forcing calendars are synchronized, we favor using the more realistic interannually varying forcing in future simulations, given the availability of the forcing data sets.

  11. Interannual Variation in Phytoplankton Class-Specific Primary Production at a Global Scale

    NASA Technical Reports Server (NTRS)

    Rousseaux, Cecile Severine; Gregg, Watson W.

    2014-01-01

    We used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of 4 phytoplankton groups to the total primary production. First we assessed the contribution of each phytoplankton groups to the total primary production at a global scale for the period 1998-2011. Globally, diatoms were the group that contributed the most to the total phytoplankton production (50, the equivalent of 20 PgC y-1. Coccolithophores and chlorophytes each contributed to 20 (7 PgC y-1 of the total primary production and cyanobacteria represented about 10 (4 PgC y(sub-1) of the total primary production. Primary production by diatoms was highest in high latitude (45) and in major upwelling systems (Equatorial Pacific and Benguela system). We then assessed interannual variability of this group-specific primary production over the period 1998-2011. Globally the annual relative contribution of each phytoplankton groups to the total primary production varied by maximum 4 (1-2 PgC y-1. We assessed the effects of climate variability on the class-specific primary production using global (i.e. Multivariate El Nio Index, MEI) and regional climate indices (e.g. Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability as indicated by significant correlation (p 0.05) between the MEI and the class-specific primary production from all groups except coccolithophores. In the Atlantic, climate variability as indicated by NAO was significantly correlated to the primary production of 2 out of the 4 groups in the North Central Atlantic (diatomscyanobacteria) and in the North Atlantic (chlorophytes and coccolithophores). We found that climate variability as indicated by SAM had only a limited effect on the class-specific primary production in the Southern Ocean. These results provide a modeling and

  12. Interannual Variations and Trends in Global Land Surface Phenology Derived from Enhanced Vegetation Index During 1982-2010

    NASA Technical Reports Server (NTRS)

    Zhang, Xiaoyang; Tan, Bin; Yu, Yunyue

    2014-01-01

    Land swiace phenology is widely retrieved from satellite observations at regional and global scales, and its long-term record has been demonstmted to be a valuable tool for reconstructing past climate variations, monitoring the dynamics of terrestrial ecosystems in response to climate impacts, and predicting biological responses to future climate scenarios. This srudy detected global land surface phenology from the advanced very high resolution radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) data from 1982 to 2010. Based on daily enhanced vegetation index at a spatial resolution of 0.05 degrees, we simulated the seasonal vegetative trajectory for each individual pixel using piecewise logistic models, which was then used to detect the onset of greenness increase (OGI) and the length of vegetation growing season (GSL). Further, both overall interannual variations and pixel-based trends were examIned across Koeppen's climate regions for the periods of 1982-1999 and 2000-2010, respectively. The results show that OGI and OSL varied considerably during 1982-2010 across the globe. Generally, the interarmual variation could be more than a month in precipitation-controlled tropical and dry climates while it was mainly less than 15 days in temperature-controlled temperate, cold, and polar climates. OGI, overall, shifted early, and GSL was prolonged from 1982 to 2010 in most climate regions in North America and Asia while the consistently significant trends only occurred in cold climate and polar climate in North America. The overall trends in Europe were generally insignificant. Over South America, late OGI was consistent (particularly from 1982 to 1999) while either positive or negative OSL trends in a climate region were mostly reversed between the periods of 1982-1999 and 2000-2010. In the Northern Hemisphere of Africa, OGI trends were mostly insignificant, but prolonged GSL was evident over individual climate regions during the last 3

  13. Interannual and intra-annual variability of rainfall in Haiti (1905-2005)

    NASA Astrophysics Data System (ADS)

    Moron, Vincent; Frelat, Romain; Jean-Jeune, Pierre Karly; Gaucherel, Cédric

    2015-08-01

    The interannual variability of annual and monthly rainfall in Haiti is examined from a database of 78 rain gauges in 1905-2005. The spatial coherence of annual rainfall is rather low, which is partly due to Haiti's rugged landscape, complex shoreline, and surrounding warm waters (mean sea surface temperatures >27 °C from May to December). The interannual variation of monthly rainfall is mostly shaped by the intensity of the low-level winds across the Caribbean Sea, leading to a drier- (or wetter-) than-average rainy season associated with easterly (or westerly) anomalies, increasing (or decreasing) winds. The varying speed of low-level easterlies across the Caribbean basin may reflect at least four different processes during the year: (1) an anomalous trough/ridge over the western edge of the Azores high from December to February, peaking in January; (2) a zonal pressure gradient between Eastern Pacific and the tropical Northern Atlantic from May/June to September, with a peak in August (i.e. lower-than-average rainfall in Haiti is associated with positive sea level pressure anomalies over the tropical North Atlantic and negative sea level pressure anomalies over the Eastern Pacific); (3) a local ocean-atmosphere coupling between the speed of the Caribbean Low Level Jet and the meridional sea surface temperature (SST) gradient across the Caribbean basin (i.e. colder-than-average SST in the southern Caribbean sea is associated with increased easterlies and below-average rainfall in Haiti). This coupling is triggered when the warmest Caribbean waters move northward toward the Gulf of Mexico; (4) in October/November, a drier- (or wetter-) than-usual rainy season is related to an almost closed anticyclonic (or cyclonic) anomaly located ENE of Haiti on the SW edge of the Azores high. This suggests a main control of the interannual variations of rainfall by intensity, track and/or recurrence of tropical depressions traveling northeast of Haiti. During this period, the

  14. Interannual and intra-annual variability of rainfall in Haiti (1905-2005)

    NASA Astrophysics Data System (ADS)

    Moron, Vincent; Frelat, Romain; Jean-Jeune, Pierre Karly; Gaucherel, Cédric

    2014-09-01

    The interannual variability of annual and monthly rainfall in Haiti is examined from a database of 78 rain gauges in 1905-2005. The spatial coherence of annual rainfall is rather low, which is partly due to Haiti's rugged landscape, complex shoreline, and surrounding warm waters (mean sea surface temperatures >27 °C from May to December). The interannual variation of monthly rainfall is mostly shaped by the intensity of the low-level winds across the Caribbean Sea, leading to a drier- (or wetter-) than-average rainy season associated with easterly (or westerly) anomalies, increasing (or decreasing) winds. The varying speed of low-level easterlies across the Caribbean basin may reflect at least four different processes during the year: (1) an anomalous trough/ridge over the western edge of the Azores high from December to February, peaking in January; (2) a zonal pressure gradient between Eastern Pacific and the tropical Northern Atlantic from May/June to September, with a peak in August (i.e. lower-than-average rainfall in Haiti is associated with positive sea level pressure anomalies over the tropical North Atlantic and negative sea level pressure anomalies over the Eastern Pacific); (3) a local ocean-atmosphere coupling between the speed of the Caribbean Low Level Jet and the meridional sea surface temperature (SST) gradient across the Caribbean basin (i.e. colder-than-average SST in the southern Caribbean sea is associated with increased easterlies and below-average rainfall in Haiti). This coupling is triggered when the warmest Caribbean waters move northward toward the Gulf of Mexico; (4) in October/November, a drier- (or wetter-) than-usual rainy season is related to an almost closed anticyclonic (or cyclonic) anomaly located ENE of Haiti on the SW edge of the Azores high. This suggests a main control of the interannual variations of rainfall by intensity, track and/or recurrence of tropical depressions traveling northeast of Haiti. During this period, the

  15. Hawaiian albatrosses track interannual variability of marine habitats in the North Pacific

    NASA Astrophysics Data System (ADS)

    Kappes, Michelle A.; Shaffer, Scott A.; Tremblay, Yann; Foley, David G.; Palacios, Daniel M.; Robinson, Patrick W.; Bograd, Steven J.; Costa, Daniel P.

    2010-07-01

    We studied the foraging behavior and marine habitats used by Laysan ( Phoebastria immutabilis) and Black-footed ( Phoebastria nigripes) Albatrosses, during four consecutive breeding seasons to investigate whether these marine predators changed habitat preferences, foraging distributions, or both, in accordance with natural interannual variability in the marine environment. We used satellite telemetry to track a total of 37 Laysan and 36 Black-footed Albatrosses during the incubation periods of 2002-2006 at Tern Island, Northwest Hawaiian Islands. First passage time analysis was used to determine search effort of individual albatrosses along their respective tracks, and this metric was then related to oceanographic habitat variables using linear mixed-effects regression. The majority of individuals traveled to pelagic waters of the North Pacific, with Laysan Albatrosses demonstrating a more northwesterly distribution from the breeding colony. Laysan Albatrosses traveled farther, for longer periods, and demonstrated greater interannual variability in trip characteristics than Black-footed Albatrosses. For Laysan Albatrosses, maximum trip distance was negatively correlated with body mass change during foraging and overall breeding success. There was considerable interspecific segregation of foraging habitats, and low overlap of foraging distributions between years. For all years, and both species, sea surface temperature was consistently the most important environmental variable predicting search effort of albatrosses, suggesting that both species use similar environmental cues when searching for prey. In the context of climate variability, our results suggest that Hawaiian albatrosses demonstrate flexibility in foraging strategies and track preferred marine habitats. However, adjusting foraging behavior to climatic variability may have energetic, and subsequent reproductive consequences.

  16. Seasonal and interannual litter dynamics of a tropical semideciduous forest of the southern Amazon Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Sanches, Luciana; Valentini, Carla Maria Abido; Júnior, Osvaldo Borges Pinto; de Souza Nogueira, José; Vourlitis, George Louis; Biudes, Marcelo Sacardi; da Silva, Carlos José; Bambi, Paulino; de Almeida Lobo, Francisco

    2008-12-01

    This study analyzed how seasonal and interannual variations in climate alter litter dynamics, including production, decomposition, and accumulation. Monthly measurements of leaf, stem, and reproductive (flower plus fruit) litter and the forest floor litter mass were combined with a mass balance model to determine rates of litter decomposition for a semideciduous tropical forest located in the rain forest-savanna ecotone of the southern Amazon Basin for 2001-2007. Annual rates of litter production varied between 8 and 10.5 Mg ha-1 a-1, and leaf litter production accounted for the majority (˜70%) of the total litter production. Leaf litter production peaked at the end of the May-August dry season while stem litter production peaked during the wet season and reproductive litter production peaked during the dry-wet season transition. Forest floor litter mass ranged between 5 and 8 Mg ha-1 over the study period and generally declined as litter inputs declined. Litter decomposition rates were remarkably stable from year-to-year and varied between 10.8 and 12.4 Mg ha-1 a-1. On average, rates of litter decomposition were highest during the dry-wet season transition. Overall, our results suggest that rainfall variability directly altered litter production dynamics and indirectly altered forest floor litter mass and decomposition kinetics through its effect on litter production. Future changes in seasonal and/or interannual rainfall patterns, whether in response to El Niño or to anthropogenic climate change, will likely have important consequences for the litter dynamics of Amazonian semideciduous forest.

  17. Interannual variability in the atmospheric CO2 rectification over a boreal forest region

    NASA Astrophysics Data System (ADS)

    Chen, Baozhang; Chen, Jing M.; Worthy, Douglas E. J.

    2005-08-01

    Ecosystem CO2 exchange with the atmosphere and the planetary boundary layer (PBL) dynamics are correlated diurnally and seasonally. The strength of this kind of covariation is quantified as the rectifier effect, and it affects the vertical gradient of CO2 and thus the global CO2 distribution pattern. An 11-year (1990-1996, 1999-2002), continuous CO2 record from Fraserdale, Ontario (49°52'29.9″N, 81°34'12.3″W), along with a coupled vertical diffusion scheme (VDS) and ecosystem model named Boreal Ecosystem Productivity Simulator (BEPS), are used to investigate the interannual variability of the rectifier effect over a boreal forest region. The coupled model performed well (r2 = 0.70 and 0.87, at 40 m at hourly and daily time steps, respectively) in simulating CO2 vertical diffusion processes. The simulated annual atmospheric rectifier effect varies from 3.99 to 5.52 ppm, while the diurnal rectifying effect accounted for about a quarter of the annual total (22.8˜28.9%).The atmospheric rectification of CO2 is not simply influenced by terrestrial source and sink strengths, but by seasonal and diurnal variations in the land CO2 flux and their interaction with PBL dynamics. Air temperature and moisture are found to be the dominant climatic factors controlling the rectifier effect. The annual rectifier effect is highly correlated with annual mean temperature (r2 = 0.84), while annual mean air relative humidity can explain 51% of the interannual variation in rectification. Seasonal rectifier effect is also found to be more sensitive to climate variability than diurnal rectifier effect.

  18. Interannual variability of Eastern China Summer Rainfall: the origins of the meridional triple and dipole modes

    NASA Astrophysics Data System (ADS)

    He, Chao; Lin, Ailan; Gu, Dejun; Li, Chunhui; Zheng, Bin; Zhou, Tianjun

    2017-01-01

    The Eastern China Summer Rainfall (ECSR) has a strong interannual variability, and the leading mode of interannual ECSR variability is characterized by either meridional triple or dipole structures as claimed by previous studies. In this study, decadal differences of the leading ECSR modes are investigated, using observational data and long-term integrations of climate models. Observational analyses show that the leading mode of ECSR is characterized by a meridional triple structure during 1979-1993 whereas a meridional dipole structure during 1994-2014. In the 200-year air-sea coupled simulation of Community Climate System Model version 4 (CCSM4), the leading mode of ECSR is characterized by triple structure in some decades whereas dipole structure in other decades, and decadal shifts between the triple and dipole structures are seen. In the 200-year simulation of the stand-alone atmospheric component of CCSM4 (i.e., CAM4) forced by fixed SST annual cycle, the triple mode and dipole mode are also identified, suggesting both of these two modes and their decadal shift can be generated by atmospheric internal dynamics without air-sea interaction. As agreed by observation, CCSM4 and CAM4 simulations, the positive (negative) phase of the triple leading mode is associated with enhanced (weakened) western north Pacific subtropical high, southward (northward) shifted East Asian jet, and meridional wave train along the East Asian coast. The positive (negative) phase of the dipole leading mode is associated with enhanced (weakened) western north Pacific subtropical high, enhanced (weakened) East Asian jet, and zonal wave train over mid-latitude Eurasian continent.

  19. Inter-annual Variability of Aboveground Net Primary Productivity in Regenerating Tropical Dry Forests

    NASA Astrophysics Data System (ADS)

    Powers, J. S.; Becknell, J. M.

    2015-12-01

    Globally, there are now more secondary forests regenerating following anthropogenic disturbance than primary forests. However, carbon dynamics in secondary tropical forests in general, and seasonally dry forests in particular, have not been as well studied as primary wet forests. Young, regenerating forests may be more sensitive to climatic variability than older forests because of their dynamic demographic rates. Similarly, seasonally dry tropical forests may be particularly sensitive to changes in precipitation, as tree growth is highly constrained by water availability. We examined how inter-annual variability in precipitation affected above-ground net primary productivity in chronosequences of dry forest in Costa Rica. Our sites included three forest cover types, whose distribution is linked to edaphic variation. Over our 6-yr dataset, annual rainfall varied from 1110 to 3040mm, with a 5-6 month dry season. ANPP ranged from 2.96 to 18.98 Mg ha-1 across sites that have been recovering for 7 to 67 years. Fine litter production dominated ANPP, and increased with forest age but not annual rainfall. By contrast, woody stem growth did not vary among forests that differed in age, but increased as a function of annual rainfall. These results differed by forest type. Lowland oak forests on low fertility soil had the lowest productivity and responses to rainfall, whereas forests on the highest fertility soils showed large increases in woody production with rainfall. Consistent with our expectation, younger forests on the intermediate soil type had higher variability in ANPP than older forests, but this was not significant for forests on the poor or high fertility soils. Our results highlight several important findings: 1) different components of ANPP vary in their responses to inter-annual variation in rainfall, 2) forest responses to climatic variability depend on species composition, which varies consistently with soil type in this landscape.

  20. Interannual Variations of Shallow Firn Temperature at Greenland Summit

    NASA Technical Reports Server (NTRS)

    Jun, Li; Wang, W. L.; Zwally, H. J.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Firn-temperature profiles are calculated in a thermal model using continuous surface temperatures derived from Automatic Weather Station (AWS) data and passive microwave data in the Greenland Summit region during the period 1987-1999. The results show that significant interannual variations of mean summer (June to August) and annual temperatures occur in the top 15 m, in addition to the normal seasonal cycle of firn temperature. At 5 m depth, the seasonal cycle is damped to 13% of the surface seasonal amplitude, but even at 15 m about 1% or 0.6 C of the seasonal cycle persists. Both summer and mean annual temperatures decrease from 1987 to 1992, followed by a general increasing trend. Interannual variability is 5 C at the surface, but only is only dampened to 3.2 C at 10 m depth and 0.7 C at 15 m depth. Dampening of the interannual variability with depth is slower than dampening of the seasonal cycle, because of the longer time constant of the interannual variation. The warmer spring and summer temperatures experienced in the top 5 m, due to both the seasonal cycle and interannual variations, affect the rate of firn densification, which is non-linearly dependent on temperature. During the 12 year period 1987-1999, the mean annual surface temperature is -29.2 C, and the mean annual 15 m temperature is -30. 1 C, which is more than 1 C warmer than a 15-m borehole temperature representing the period of about 1959 and warmer than the best-fit temperature history by Alley and Koci back to 1500 A.D..

  1. Analysis of seasonal and interannual variability in transpacific transport

    NASA Astrophysics Data System (ADS)

    Liu, Junfeng; Mauzerall, Denise L.; Horowitz, Larry W.

    2005-02-01

    The purpose of our analysis is both to evaluate the meteorological component of the seasonal and interannual variability of transpacific transport and to identify meteorological features that can be used to estimate transpacific transport. To accomplish this goal, we simulate the transport of nine continental tracers with uniform emissions and two-week lifetimes using the global Model of Ozone and Related Tracers Version 2 (MOZART-2) driven with NCEP reanalysis meteorology from 1991-2001. In addition, we define a transpacific "transport potential," a measure of the quantity of a tracer transported from a particular region normalized by its total emissions from that region, across a meridional plane in the eastern Pacific at 130°W. We find that at midlatitudes, the east Asian and Indian tracers have the largest transport potentials, particularly in spring. The interannual variability of the transpacific transport potentials of most tracers is relatively high in winter and fall (particularly in February and September) but is low from April to August. At high latitudes the former Soviet Union, east Asian, and European tracers have the largest transpacific transport potentials, especially in late summer and fall, when the lowest interannual variability is observed. We find that El Niño winters are associated with stronger eastward transport of east Asian emissions in the subtropical eastern Pacific. Transport of the east Asian tracer in the central North Pacific is well correlated with the North Pacific Index. However, we find that the interannual variability of transport across the west coast of North America is mostly driven by local meteorology. We therefore created a new index based on meteorology over the eastern Pacific, which we call the Eastern Pacific Index (EPI). The EPI captures most of the interannual variability of transpacific transport at both middle- and high-latitude regions across the west coast of North America.

  2. Recurrent inguinal hernia.

    PubMed Central

    Postlethwait, R W

    1985-01-01

    An analysis of 584 operations for recurrent inguinal hernia was made in an attempt to determine the cause of the recurrence based on the anatomic findings. The recurrence was indirect in 300, direct in 241, and various other in 43 operations. The causes of the indirect recurrences appeared to be an unrecognized hernia, incomplete dissection or improper ligation of the sac, failure to narrow the cord, or inadequate reconstruction of the internal ring. No cause for the diffuse direct recurrences was apparent. Of the 241 hernias in Hesselbach's triangle, 144 were small localized defects, usually (112) just lateral to the symphysis. These were considered to be caused by the cutting action of a suture placed under tension. On the basis of these findings, suggestions are made for primary inguinal hernia operations. PMID:4073990

  3. Detecting a Terrestrial Biosphere Sink for Carbon Dioxide: Interannual Ecosystem Modeling for the Mid-1980s

    NASA Technical Reports Server (NTRS)

    Potter, Christopher S.; Klooster, Steven A.; Brooks, Vanessa; Gore, Warren J. (Technical Monitor)

    1998-01-01

    There is considerable uncertainty as to whether interannual variability in climate and terrestrial ecosystem production is sufficient to explain observed variation in atmospheric carbon content over the past 20-30 years. In this paper, we investigated the response of net CO2 exchange in terrestrial ecosystems to interannual climate variability (1983 to 1988) using global satellite observations as drivers for the NASA-CASA (Carnegie-Ames-Stanford Approach) simulation model. This computer model of net ecosystem production (NEP) is calibrated for interannual simulations driven by monthly satellite vegetation index data (NDVI) from the NOAA Advanced Very High Resolution Radiometer (AVHRR) at 1 degree spatial resolution. Major results from NASA-CASA simulations suggest that from 1985 to 1988, the northern middle-latitude zone (between 30 and 60 degrees N) was the principal region driving progressive annual increases in global net primary production (NPP; i.e., the terrestrial biosphere sink for carbon). The average annual increase in NPP over this predominantly northern forest zone was on the order of +0.4 Pg (10 (exp 15) g) C per year. This increase resulted mainly from notable expansion of the growing season for plant carbon fixation toward the zonal latitude extremes, a pattern uniquely demonstrated in our regional visualization results. A net biosphere source flux of CO2 in 1983-1984, coinciding with an El Nino event, was followed by a major recovery of global NEP in 1985 which lasted through 1987 as a net carbon sink of between 0.4 and 2.6 Avg C per year. Analysis of model controls on NPP and soil heterotrophic CO2 fluxes (Rh) suggests that regional warming in northern forests can enhance ecosystem production significantly. In seasonally dry tropical zones, periodic drought and temperature drying effects may carry over with at least a two-year lag time to adversely impact ecosystem production. These yearly patterns in our model-predicted NEP are consistent in

  4. Interannual variability of solar irradiance over the Amazon Basin including the 1982-83 El Nino Year

    NASA Technical Reports Server (NTRS)

    Pinker, Rachel T.; Laszlo, I.

    1992-01-01

    Surface solar irradiance was derived over the extended Amazon Basin using AVHRR observations from polar-orbiting satellites during four July months (1983-1986). Observations from the geostationary satellite GOES for July 1983 were also used to assess diurnal effects. Both satellite datasets are part of the Satellite Cloud Climatology Project (ISCCP) B3 product. It was demonstrated that it is now possible to derive long-term surface solar irradiance, which can be useful in climate studies, and that the accuracy of the derived fields is sufficient to detect interannual differences that can exceed at times 70 W/sq m.

  5. Interannual Variation in Phytoplankton Concentration and Community in the Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Rousseaux, C. S.; Gregg, W. W.

    2011-01-01

    Climate events such as El Nino have been shown to have an effect on the biology of our ocean. Because of the lack of data, we still have very little knowledge about the spatial and temporal effect these climate events may have on biological marine systems. In this study, we used the NASA Ocean Biogeochemical Model (NOBM) to assess the interannual variability in phytoplankton community in the Pacific Ocean between 1998 and 2005. In the North Central and Equatorial Pacific Ocean, changes in the Multivariate El Nino Index were associated with changes in phytoplankton composition. The model identified an increase in diatoms of approx.33 % in the equatorial Pacific in 1999 during a La Nina event. This increase in diatoms coincided with a decrease of approx.11 % in cyanobacteria concentration. The inverse relationship between cyanobacteria and diatoms concentration was significant (p<0.05) throughout the period of study. The use of a numerical model allows us to assess the impact climate variability has on key phytoplankton groups known to lead to contrasting food chain at a spatial and temporal resolution unachievable when relying solely on in-situ observations.

  6. Interannual Variation in Phytoplankton Class-specific Primary Production at a Global Scale

    NASA Technical Reports Server (NTRS)

    Rousseaux, Cecile; Gregg, Watson

    2014-01-01

    Phytoplankton is responsible for over half of the net primary production on earth. The knowledge on the contribution of various phytoplankton groups to the total primary production is still poorly understood. Data from satellite observations suggest that for upwelling regions, photosynthetic rates by microplankton is higher than that of nanoplankton but that when the spatial extent is considered, the production by nanoplankton is comparable or even larger than microplankton. Here, we used the NASA Ocean Biogeochemical Model (NOBM) combined with remote sensing data via assimilation to evaluate the contribution of 4 phytoplankton groups to the total primary production. Globally, diatoms were the group that contributed the most to the total phytoplankton production (approx. 50%) followed by coccolithophores and chlorophytes. Primary production by diatoms was highest in high latitude (>45 deg) and in major upwelling systems (Equatorial Pacific and Benguela system). We assessed the effects of climate variability on the class-specific primary production using global (i.e. Multivariate El Nino Index, MEI) and 'regional' climate indices (e.g. Southern Annular Mode (SAM), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO)). Most interannual variability occurred in the Equatorial Pacific and was associated with climate variability. These results provide a modeling and data assimilation perspective to phytoplankton partitioning of primary production and contribute to our understanding of the dynamics of the carbon cycle in the oceans at a global scale.

  7. Coping with Fear of Recurrence

    MedlinePlus

    ... With Fear of Recurrence Request Permissions Coping With Fear of Recurrence Approved by the Cancer.Net Editorial ... affects your life. Tips for coping with the fear of recurrence Living with uncertainty is never easy. ...

  8. 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

  9. Predictors of Recurrent AKI.

    PubMed

    Siew, Edward D; Parr, Sharidan K; Abdel-Kader, Khaled; Eden, Svetlana K; Peterson, Josh F; Bansal, Nisha; Hung, Adriana M; Fly, James; Speroff, Ted; Ikizler, T Alp; Matheny, Michael E

    2016-04-01

    Recurrent AKI is common among patients after hospitalized AKI and is associated with progressive CKD. In this study, we identified clinical risk factors for recurrent AKI present during index AKI hospitalizations that occurred between 2003 and 2010 using a regional Veterans Administration database in the United States. AKI was defined as a 0.3 mg/dl or 50% increase from a baseline creatinine measure. The primary outcome was hospitalization with recurrent AKI within 12 months of discharge from the index hospitalization. Time to recurrent AKI was examined using Cox regression analysis, and sensitivity analyses were performed using a competing risk approach. Among 11,683 qualifying AKI hospitalizations, 2954 patients (25%) were hospitalized with recurrent AKI within 12 months of discharge. Median time to recurrent AKI within 12 months was 64 (interquartile range 19-167) days. In addition to known demographic and comorbid risk factors for AKI, patients with longer AKI duration and those whose discharge diagnosis at index AKI hospitalization included congestive heart failure (primary diagnosis), decompensated advanced liver disease, cancer with or without chemotherapy, acute coronary syndrome, or volume depletion, were at highest risk for being hospitalized with recurrent AKI. Risk factors identified were similar when a competing risk model for death was applied. In conclusion, several inpatient conditions associated with AKI may increase the risk for recurrent AKI. These findings should facilitate risk stratification, guide appropriate patient referral after AKI, and help generate potential risk reduction strategies. Efforts to identify modifiable factors to prevent recurrent AKI in these patients are warranted.

  10. The climate sensitivity of food security in Mali - a historical perspective on availability and access dimensions

    NASA Astrophysics Data System (ADS)

    Giannini, A.; Krishnamurthy, P. K.; Cousin, R.; Choularton, R. J.

    2011-12-01

    We present results based on an analysis of a 2005 livelihood survey of ~2000 rural households in ~200 villages scattered across Mali, a sparsely populated, large land-locked country in West Africa, to elucidate the role of climate variability and change in shaping availability and access dimensions of food security. The Comprehensive Food Security Vulnerability Analysis is a recurrent survey carried out by the World Food Programme and in-country partners to map out nutritional and socio-economic status during normal (~food secure) conditions in the hope of understanding underlying cause(s) and prevent the next food security crisis. We set the spatial characterization of food security that emerges from the CFSVA against the background of a varying climate, on intra-seasonal, interannual and multi-decadal time scales: through elucidation of the influence of climate on agricultural production we arrive at an interpretation of structural and conjunctural events affecting food security. We conclude with a discussion of possible interventions to reduce vulnerability.

  11. Climate Modeling and Prediction at NSIPP

    NASA Technical Reports Server (NTRS)

    Suarez, Max; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The talk will review modeling and prediction efforts undertaken as part of NASA's Seasonal to Interannual Prediction Project (NSIPP). The focus will be on atmospheric model results, including its use for experimental seasonal prediction and the diagnostic analysis of climate anomalies. The model's performance in coupled experiments with land and atmosphere models will also be discussed.

  12. Interannual vs decadal SST forced responses of the West African monsoon

    NASA Astrophysics Data System (ADS)

    Rodríguez-Fonseca, Belen

    2010-05-01

    One of the strongest interdecadal signals on the planet has been observed in the Sahelian rainfall during the second half of the XXth century, from wet conditions in the 50's and 60's to drier conditions after the 70's. Parallel to this, several decadal signals have experienced a change from the 70's, and also the influence of the global warming has increased from this decade. From a global perspective the West African rainfall variability is highly modulated by SST forced signals. Many works have pointed out to the Atlantic and Pacific equatorial modes influence on interannual timescales; and to the AMO and the Pacific and Indian Ocean at multidecadal timescales. In the AMMA-EU context the modulation of the interannual modes by the decadal variability together with the influence of the GW has been studied by analysing the interannual modes of variability before and after the 70's. The results indicate the presence of different interannual telecconections between these two periods and, hence, of different anomalous rainfall responses. The importance of the background state modulated by multidecadal variability in the interannual modes is stated in this work. Also, an interesting discussion appears if we wonder whether or not the background state is affected, in turn, by anthropogenic climate change. Recent observational and GCM studies have shown, following the results of Polo et al. (2008), how the Atlantic and Pacific Niños present a dynamical link during the last decades of the XX century (Rodriguez-Fonseca et al., 2009). In this way, the positive (negative) phase of the summer Pacific Niño signal has been found to be connected with a negative (positive) phase of the Equatorial Atlantic mode (EM or Atlantic Niño, Polo et al., 2008); a pattern which leads the summer Atlantic variability. The determinant impact of this connection on the WA monsoon has been addressed by defining a global summer tropical mode accounting for more than the 60% of the rainfall

  13. Interannual variability versus seasonal variability in the tropical Atlantic

    NASA Technical Reports Server (NTRS)

    Picaut, J.; Servain, J.; Seva, M.; Busalacchi, A. J.

    1984-01-01

    Monthly fields of sea surface temperature and wind stress for the tropical Atlantic are constructed for January 1964 to December 1979. Inside the Gulf of Guinea the amplitude of the seasonal variability of SST ranges between 2.5 and 4 times greater than the interannual variability. In the remainder of the equatorial Atlantic this measure is less than 2. Standard deviations of wind stress anomalies indicate that, except near the Intertropical Convergence Zone, the magnitude of interannual fluctuations is greater than that of seasonal ones. The joint analyses of these SST and wind stress fields indicate the largest positive SST anomaly in the Gulf of Guinea (July, 1968) was immediately preceded by the only reversal of the trade winds west along the equator.

  14. 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.

  15. 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.

  16. On the Vertical Structure of Seasonal, Interannual and Intraseasonal Flows

    DTIC Science & Technology

    1992-12-01

    the Vertical Structure of Seasonal, Interannual and Intraseasonal Flows b, AUTHOR(S) Steven Reino Gilbert,Major -. Pf.IFORI.MINt ORGAN!?ATION NAMW(S...AND INTRASEASONAL FLOWS by Steven Reino Gilbert A dissertation submitted to the faculty of The University of Utah in partial fulffifment of the...requirements for the degree of Doctor of Philosophy Department of Meteorology The University of Utah La ! December 1992 Copyright @ Steven Reino Gilbert 1992

  17. Interannual Variability In the Atmospheric CO2 Rectification Over Boreal Forests Based On A Coupled Ecosystem-Atmosphere Model

    NASA Astrophysics Data System (ADS)

    Chen, B.; Chen, J. M.; Worthy, D.

    2004-05-01

    Ecosystem CO2 exchange and the planetary boundary layer (PBL) are correlated diurnally and seasonally. The simulation of this atmospheric rectifier effect is important in understanding the global CO2 distribution pattern. A 12-year (1990-1996, 1999-2003), continuous CO2 measurement record from Fraserdale, Ontario (located ~150 km north of Timmons), along with a coupled Vertical Diffusion Scheme (VDS) and ecosystem model (Boreal Ecosystem Productivity Simulator, BEPS), is used to investigate the interannual variability in this effect over a boreal forest region. The coupled model performed well in simulating CO2 vertical diffusion processes. Simulated annual atmospheric rectifier effects, (including seasonal and diurnal), quantified as the variation in the mean CO2 concentration from the surface to the top of the PBL, varied from 2.8 to 4.1 ppm, even though the modeled seasonal variations in the PBL depth were similar throughout the 12-year period. The differences in the interannual rectifier effect primarily resulted from changes in the biospheric CO2 uptake and heterotrophic respiration. Correlations in the year-to year variations of the CO2 rectification were found with mean annual air temperatures, simulated gross primary productivity (GPP) and heterotrophic respiration (Rh) (r2=0.5, 0.46, 0.42, respectively). A small increasing trend in the CO2 rectification was also observed. The year-to-year variation in the vertical distribution of the monthly mean CO2 mixing ratios (reflecting differences in the diurnal rectifier effect) was related to interannual climate variability, however, the seasonal rectifier effects were found to be more sensitive to climate variability than the diurnal rectifier effects.

  18. Interannual variability of snowmelt in the Sierra Nevada and Rocky Mountains, United States: examples from two alpine watersheds

    USGS Publications Warehouse

    Jepsen, Steven M.; Molotch, Noah P.; Williams, Mark W.; Rittger, Karl E.; Sickman, James O.

    2012-01-01

    The distribution of snow and the energy flux components of snowmelt are intrinsic characteristics of the alpine water cycle controlling the location of source waters and the effect of climate on streamflow. Interannual variability of these characteristics is relevant to the effect of climate change on alpine hydrology. Our objective is to characterize the interannual variability in the spatial distribution of snow and energy fluxes of snowmelt in watersheds of a maritime setting, Tokopah Basin (TOK) in California's southern Sierra Nevada, and a continental setting, Green Lake 4 Valley (GLV4) in Colorado's Front Range, using a 12 year database (1996–2007) of hydrometeorological observations and satellite-derived snow cover. Snowpacks observed in GLV4 exhibit substantially greater spatial variability than in TOK (0.75 versus 0.28 spatial coefficient of variation). In addition, modeling results indicate that the net turbulent energy flux contribution to snowmelt in GLV4 is, on average, 3 times greater in magnitude (mean 29% versus 10%) and interannual variability (standard deviation 17% versus 6%) than in TOK. These energy flux values exhibit strong seasonality, increasing as the melt season progresses to times later in the year (R2 = 0.54–0.77). This seasonality of energy flux appears to be associated with snowmelt rates that generally increase with onset date of melt (0.02 cm d-2). This seasonality in snowmelt rate, coupled to differences in hydrogeology, may account for the observed differences in correspondence between the timing of snowmelt and timing of streamflow in these watersheds.

  19. Interannual variation of East Asian Winter Monsoon and ENSO

    SciTech Connect

    Zhang, Yi; Sperber, Kenneth R.; Boyle, James S.

    1996-12-01

    This paper examines the interannual variation of the East Asian winter monsoon and its relationship with EJSO based on the 1979-1995 NCEP/NCAR reanalysis. Two stratifications of cold surges are used. The first one, described as the conventional cold surges, indicates that the surge frequency reaches a urn one year after El Nino events. The second one, originated from the same region as the first, is defined as the maximum wind events near the South China Sea. The variation of this stratification of surges is found to be in good agreement with the South Oscillation Index (SOI). Low SOI (high SOI) events coincide with years of low (high) surge frequency. The interannual variation of averaged meridional wind near the South China Sea and western Pacific is dominated by the South China Sea cold surges, and is also well correlated (R--O.82) with the SOI. Strong wind seasons are associated with La Nina and high SOI events; likewise, weak wind years are linked with El Nino and low SOI cases. This pattern is restricted north of the equator within the region of (OON-20 N, 11OOE-1300E), and is confined to the near surface layer. The surface Siberian high, 500 hPa trough and 200 hPa jetstream, all representing the large-scale monsoon flow, are found to be weaker than normal during El Nino years. In particular, the interannual variation of the Siberian high is in general agreement with the SOL.

  20. Modeling interannual variability in the Martian seasonal CO2 cycle

    NASA Technical Reports Server (NTRS)

    Wood, S. E.; Paige, D. A.

    1992-01-01

    One aspect of the seasonal pressure variations measured at the Viking Lander sites is their nearly perfect interannual repeatability. This presents a problem because it implies that the behavior of the seasonal polar caps should be highly repeatable from year to year as well. There are a number of observations and theories suggesting that the presence of dust and water ice clouds in the Martian atmosphere should have significant direct and indirect effects on the rates of CO2 condensation and sublimation in the north and south polar regions. These effects include (1) reduced rates of CO2 frost condensation during polar night seasons due to the radiative effects of dust and water ice clouds and associated CO2 clouds or elevated atmospheric temperatures and (2) reduced or elevated rates of frost sublimation due to the radiative effects of atmospheric dust or to changes in frost emissivities and albedos due to contamination by water ice and dust. The Viking Landing pressure observations are examined to determine the range and character of the interannual variations present. Then a diurnal and seasonal thermal model is used to examine the effects of interannual variations in the polar heat balance on seasonal pressure variations.

  1. Wind-driven interannual variability over the northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Cummins, Patrick F.; Lagerloef, Gary S. E.

    2004-12-01

    Interannual variability of the sea surface height (SSH) over the northeast Pacific Ocean is hindcast with a reduced-gravity, quasi-geostrophic model that includes linear damping. The model is forced with monthly Ekman pumping fields derived from the NCEP reanalysis wind stresses. The numerical solution is compared with SSH observations derived from satellite altimeter data and gridded at a lateral resolution of 1 degree. Provided that the reduced gravity parameter is chosen appropriately, the results demonstrate that the model has significant hindcast skill over interior regions of the basin, away from continental boundaries. A damping time scale of 2 to 3 years is close to optimal, although the hindcast skill is not strongly dependent on this parameter. A simplification of the quasi-geostrophic model is considered in which Rossby waves are eliminated, yielding a Markov model driven by local Ekman pumping. The results approximately reproduce the hindcast skill of the more complete quasi-geostrophic model and indicate that the interannual SSH variability is dominated by the local response to wind forcing. There is a close correspondence the two leading empirical orthogonal modes of the local model and those of the observed SSH anomalies. The latter account for over half of the variance of the interannual signal over the region.

  2. Statistical adjustment of simulated inter-annual variability in an investigation of short-term temperature trend distributions over Canada

    NASA Astrophysics Data System (ADS)

    Grenier, Patrick; Chaumont, Diane; de Elía, Ramón

    2015-04-01

    Plausible climate trajectories towards warmer temperatures are made up of a succession of positive and negative short-term trends. Cooling trends over short durations (~ 5 to 25 years) are thus to be expected, and related probabilities have to rely on simulations from physically-based climate models. However, because simulations often present offsets in many statistical properties relative to observations, it is important to address the issue of statistical adjustment prior to characterizing expected short-term trend distributions. In this paper, we discuss the impact of statistically adjusting inter-annual variability on short-term cooling probability for locations across Canada and during the current period (2006-2035). Two methods are considered, one that uses a transfer function based on the dissimilarity between simulated and observed detrended annual temperature values (residuals) during a calibration period, and another that uses an autoregressive model of the observational residuals for generating variability. Long-term trends remain invariant in both methods. Results show that although short-term trends in individual simulations are in some cases highly impacted, cooling probabilities based on a multi-model ensemble are only slightly altered by each of the two methods, due to compensational effects. In summary, this paper presents an application where final results are robust to how simulated inter-annual variability is handled.

  3. 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.

  4. An Inter-Annual Oscillation in the Western Arctic Associated with a Non Stationary Seasonally Lagged ENSO Signal

    NASA Astrophysics Data System (ADS)

    Moore, Kent; Pickart, Robert

    2015-04-01

    The late summer retreat of Arctic sea ice is one of the most dramatic and well-documented changes that has occurred in the climate system. This retreat is most pronounced in the western Arctic. Sea ice minima in this region are typically followed by years with substantially higher extents. For example, the September 2013 Arctic sea ice extent was ~30% higher than the 2012 minimum. These rebounds have caused confusion amongst the public as well as debate within the scientific and policy communities regarding this aspect of climate change. Here we demonstrate the existence of an inter-annual oscillation in the region that successfully explains the rebound of sea ice following recent minima. The oscillation is associated with local variability in atmospheric flow, including a reversal in the surface wind field, that we propose results in changes in upwelling along the shelf-edge of the Beaufort and Chukchi Seas. From the 1950s to the 1990s, the oscillation was associated with a seasonally lagged El-Nino signal, but this is no longer the case. We argue that this change represents a reduction in the influence that ENSO has on the western Arctic possibly due to the loss of the region's sea ice that has enhanced local inter-annual variability.

  5. Inter-annual sea-ice dynamics and micro-algal biomass in winter pack ice of Marguerite Bay, Antarctica

    NASA Astrophysics Data System (ADS)

    Fritsen, Christian H.; Memmott, Jeramie; Stewart, Frank J.

    2008-09-01

    The geographic remoteness, the lack of remote sensing capabilities, and the lack of appropriate environmental sensors make the detection of seasonal trends or inter-annual variations in sea-ice microbial biomass or production processes within the pack ice of the Antarctic extremely rare. The evaluation of their inter-annual variability in the context of ice dynamics and trends in regional climate has not been possible. During the late winters of 2001 (July-August) and 2002 (August-September) we assessed sea-ice dynamics, sea-ice characteristics, and biomass of sea-ice microbiota along the Western Antarctic Peninsula. These two winters were marked by large contrasts in the dates of initial ice formation (late June in 2001 and April in 2002), which resulted in differences in the physical pack-ice characteristics. Chlorophyll a (chl a) content in ice cores differed between the study years, with 2002 having 10-fold higher chl a content. The difference in ice-core chl a content is best explained by the timing of ice formation that leads to less phytoplankton scavenging from the water column and a lack of transfer of solar energy into the pack-ice ecosystem. Such a tractable atmosphere ocean-ice-biota coupling may help in evaluating underlying processes responsible for long-term trends in recruitment cycles of upper trophic levels as well as future projections on the response of the Antarctic marine ecosystems to variability in local climate.

  6. Interannual Variability of Eurasian Snow Cover in Spring and its Possible Link With Atmospheric Circulation

    NASA Astrophysics Data System (ADS)

    Igarashi, H.; Yasunari, T.

    2003-12-01

    We investigate the interannual variability of Eurasian spring snow cover extent (SCE) during 1973-1998, especially focused on the relationship between the recent decreasing trend and the year-to-year variation. Two major patterns are detected by applying EOF analysis to the interannual component of the snow cover duration at each grid point derived from the NOAA satellite measurement data set. Recent Eurasian SCE change, mainly characterized by an abrupt decrease after the end of 1980's, is identified as the first component of EOF analysis (representing 18.3% of the total variance), which is located over the eastern part of the continent and has an apparent persistency from February to August. This pattern is the representative of spring-to-summer snow cover variability over the whole Eurasia. On the other hand, another dominant mode is found over the western Russia (50-65N,40-80E) as the second component (8.6%), which has a fluctuation of about 4-6-year cycle without a significant linear trend. The regression analysis shows that in April there is a close relationship between the variation of this mode and air temperature and geopotential height fields over western Russia from surface up to stratosphere, which indicates that this mode is strongly controlled by the atmospheric circulation in spring. Furthermore, the results of the atmospheric heat budget analysis over the western Russia shows that adiabatic compression in relation to its vertical motion plays an important role for heating the atmosphere and the decision of the timing of snow cover disappearance over western Russia, while horizontal advection is always working as a heating sense independently of the interannual variation of snow cover disappearance. Diabatic processes merely affect the fluctuation of the atmospheric heating. Many numerical studies have shown the influence of the continental scale variability of land surface processes induced by snow cover on the following climate variation, and some

  7. Interannual, seasonal and diurnal Mars surface environmental cycles observed from Viking to Curiosity

    NASA Astrophysics Data System (ADS)

    Martinez, German; Vicente-Retortillo, Álvaro; Kemppinen, Osku; Fischer, Erik; Fairen, Alberto G.; Guzewich, Scott David; Haberle, Robert; Lemmon, Mark T.; Newman, Claire E.; Renno, Nilton O.; Richardson, Mark I.; Smith, Michael D.; De la Torre, Manuel; Vasavada, Ashwin R.

    2016-10-01

    We analyze in-situ environmental data from the Viking landers to the Curiosity rover to estimate atmospheric pressure, near-surface air and ground temperature, relative humidity, wind speed and dust opacity with the highest confidence possible. We study the interannual, seasonal and diurnal variability of these quantities at the various landing sites over a span of more than twenty Martian years to characterize the climate on Mars and its variability. Additionally, we characterize the radiative environment at the various landing sites by estimating the daily UV irradiation (also called insolation and defined as the total amount of solar UV energy received on flat surface during one sol) and by analyzing its interannual and seasonal variability.In this study we use measurements conducted by the Viking Meteorology Instrument System (VMIS) and Viking lander camera onboard the Viking landers (VL); the Atmospheric Structure Instrument/Meteorology (ASIMET) package and the Imager for Mars Pathfinder (IMP) onboard the Mars Pathfinder (MPF) lander; the Miniature Thermal Emission Spectrometer (Mini-TES) and Pancam instruments onboard the Mars Exploration Rovers (MER); the Meteorological Station (MET), Thermal Electrical Conductivity Probe (TECP) and Phoenix Surface Stereo Imager (SSI) onboard the Phoenix (PHX) lander; and the Rover Environmental Monitoring Station (REMS) and Mastcam instrument onboard the Mars Science Laboratory (MSL) rover.A thorough analysis of in-situ environmental data from past and present missions is important to aid in the selection of the Mars 2020 landing site. We plan to extend our analysis of Mars surface environmental cycles by using upcoming data from the Temperature and Wind sensors (TWINS) instrument onboard the InSight mission and the Mars Environmental Dynamics Analyzer (MEDA) instrument onboard the Mars 2020 mission.

  8. Interannual Variations in Tropical Upper-Tropospheric Humidity: Understanding Tropical Convective and Dynamical Processes

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Fitzjarrald, Dan E.; Miller, Timothy L.

    2005-01-01

    Uncertainty remains as to what extent variability in mid to upper tropospheric moisture, especially over the tropics, behaves as constant relative humidity during interannual climate variations associated with ENSO. Systematic variations in HIRS 6.7 micron and MLS 205 GHz suggest that dry subtropical regions evolving during warm SST events depress relative humidity, but the interpretation of these events is still uncertain. Additional specific concerns have to do with regional signatures of convective processes: How does the origin of dry air in the eastern subtropical N. Pacific differ in ENSO warm versus cold years? The dynamics of Rossby wave forcing by convective heating, subtropical jet stream dynamics, and dynamics driven subsidence all come into play here. How variations in precipitating ice hydrometeors from tropical anvils relate to variations in UTH is also a subject of debate? Do variations in precipitating ice, cloud cover and water vapor behavior show any support for the Iris-hypothesis mechanism? Here we examine historical records of SSM/T-2 data to gain a better physical understanding of the effects of deep convective moisture sources and dynamically-induced vertical circulations on UTH. These high frequency microwave measurements (183.3 GHz) take advantage of far less sensitivity to cloud hydrometeors than the 6.7 micron data to yield a record of upper tropospheric relative humidity. Furthermore, signatures of precipitating ice from these channels facilitate comparisons to TRMM hydrometeors detected by radar. In analyzing these observations, we isolate water vapor and temperature change components that affect brightness temperatures and the inferred relative humidity. Trajectory modeling is also used to understand interannual humidity anomalies in terms of outflow fbm convective regions and history of diabatically-driven sinking which modifies relative humidity.

  9. Determination of Interannual to Decadal Changes in Ice Sheet Mass Balance from Satellite Altimetry

    NASA Technical Reports Server (NTRS)

    Zwally, H. Jay; Busalacchi, Antonioa J. (Technical Monitor)

    2001-01-01

    A major uncertainty in predicting sea level rise is the sensitivity of ice sheet mass balance to climate change, as well as the uncertainty in present mass balance. Since the annual water exchange is about 8 mm of global sea level equivalent, the +/- 25% uncertainty in current mass balance corresponds to +/- 2 mm/yr in sea level change. Furthermore, estimates of the sensitivity of the mass balance to temperature change range from perhaps as much as - 10% to + 10% per K. Although the overall ice mass balance and seasonal and inter-annual variations can be derived from time-series of ice surface elevations from satellite altimetry, satellite radar altimeters have been limited in spatial coverage and elevation accuracy. Nevertheless, new data analysis shows mixed patterns of ice elevation increases and decreases that are significant in terms of regional-scale mass balances. In addition, observed seasonal and interannual variations in elevation demonstrate the potential for relating the variability in mass balance to changes in precipitation, temperature, and melting. From 2001, NASA's ICESat laser altimeter mission will provide significantly better elevation accuracy and spatial coverage to 86 deg latitude and to the margins of the ice sheets. During 3 to 5 years of ICESat-1 operation, an estimate of the overall ice sheet mass balance and sea level contribution will be obtained. The importance of continued ice monitoring after the first ICESat is illustrated by the variability in the area of Greenland surface melt observed over 17-years and its correlation with temperature. In addition, measurement of ice sheet changes, along with measurements of sea level change by a series of ocean altimeters, should enable direct detection of ice level and global sea level correlations.

  10. Interannual Differences in Cloud Albedo and Cloud Height Measured by MISR

    NASA Astrophysics Data System (ADS)

    Davies, R.

    2005-12-01

    The Multiangle Imaging SpectroRadiometer (MISR) on the Terra satellite has been operating almost flawlessly since early 2000. Terra has fuel reserves that will last until about 2014, and the instruments are funded to remain operational at least through 2009. MISR provides homogeneous time series of cloud heights, albedos, and height-resolved cloud-tracked winds that are becoming increasingly relevant to climate change studies. The cloud height record is of special interest, as it is uniquely insensitive to the radiometric calibration issues that affect most other types of satellite-derived time series. In addition, due to the extremely large number of independent samples, the expected error in the mean cloud height, on a global annual basis, is less than 10 m, or about 0.3% of the mean height, allowing subtle interannual differences to be detected. By contrast, the albedo measurements have a relative temporal uncertainty that is limited by radiometric calibration to about 1% over the mission lifetime, together with an absolute calibration uncertainty of about 3%. Two complete 12-month periods, 5/00-4/01 and 5/04-4/05, together with several of the intervening months, have now been consistently processed, allowing assessment of MISR's ability to measure interannual differences. The albedo and height fields both show remarkably consistent seasonal and regional patterns for the two full years. The global annual mean albedos differ by less than 0.6%, well within the expected radiometric uncertainty, and the regional/seasonal patterns show no coherent difference. The global mean cloud heights, on the other hand show a measurable difference of 44 m, with a sampling uncertainty of only ±7 m. The regional/seasonal patterns for cloud height distribution also show coherent differences in the behavior of high tropical clouds associated with the Intertropical Convergence Zone.

  11. Interannual Comparison of Water Vapor in the North Polar Region of Mars

    NASA Technical Reports Server (NTRS)

    Tamppari, L. K.; Smith, M. D.; Hale, A. S.; Bass, D. S.

    2003-01-01

    In order to better understand the current climate of Mars, we seek to understand atmospheric water in the north polar region. Our approach is to examine the water transport and cycling issues within the north polar region and in/out of the region on seasonal and annual timescales. Viking Mars Atmospheric Water Detector (MAWD) data showed that water vapor increased as the northern summer season progressed and temperatures increased, and that vapor appeared to be transported southward . However, there has been uncertainty about the amount of water cycling in and out of the north polar region, as evidenced by residual polar cap visible brightness changes between one Martian year (Mariner 9 data) and a subsequent year (Viking data). These changes were originally thought to be interannual variations in the amount of frost sublimed based on global dust storm activity . However, Viking thermal and imaging data were re-examined and it was found that 14-35 pr m of water -ice appeared to be deposited on the cap later in the summer season, indicating that some water may be retained and redistributed within the polar cap region. This late summer deposition could be due to adsorption directly onto the cap surface or due to snowfall. We seek to understand what happens to the water on seasonal and interannual timescales. We address these issues by examining water vapor in the north polar region of Mars during the north spring and summer period from MGS TES data and by comparing these results to the Viking MAWD results.

  12. Western tropical Pacific hydrology as inferred from northern Borneo speleothems: interannual to orbital-scale variability

    NASA Astrophysics Data System (ADS)

    Cobb, K. M.; Carolin, S.; Chen, S.; Lund, D. C.; Meckler, A. N.; Adkins, J. F.; Hoffmann, S. S.; Emile-Geay, J.; Tuen, A.; Pritchard, A.; Clark, B.; Lynch-Stieglitz, J.; Moerman, J. W.; Lejau, S.; Malang, J.

    2015-12-01

    The response of large-scale convective systems in the tropics to anthropogenic climate change remains highly uncertain, even though a large number of paleo-hydrological reconstructions suggest that such systems are sensitive to a variety of past climate forcings across a wide range of timescales. In particular, absolutely-dated speleothems from across the tropics have documented systematic shifts in convective activity that occured in response to abrupt climate change and orbital forcing over the last several glacial-interglacial cycles. In Northern Borneo, overlapping decadally- to centennially-resolved stalagmite oxygen isotopic (d18O) records spanning the last 500,000 years reveal that regional convective activity in this region is dominated by fall precessional insolation forcing, with a significant contribution from abrupt climate change events whose signature is particularly pronounced immediately preceding glacial terminations (Partin et al., 2007; Meckler et al., 2012; Carolin et al., 2013; Carolin et al., in prep). High-resolution (sub-annual) oxygen isotope sampling of select intervals of the Holocene reveals that interannual variability is most reduced at ~5.2kybp, with relatively higher variance observed in the early and late Holocene (Chen et al., in prep). The fact that boreal fall insolation at the equator peaks at ~5kybp during the Holocene implies that the strong fall insolation signal in the longer Borneo stalagmite records may reflect the modulation of the El Nino-Southern Oscillation (ENSO) by fall insolation, given the sensitivity of modern-day rainfall and dripwater d18O to ENSO variability (Moerman et al., 2013; Moerman et al., 2014).

  13. 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.

  14. What drives interannual variation in tree ring oxygen isotopes in the Amazon?

    NASA Astrophysics Data System (ADS)

    Baker, J. C. A.; Gloor, M.; Spracklen, D. V.; Arnold, S. R.; Tindall, J. C.; Clerici, S. J.; Leng, M. J.; Brienen, R. J. W.

    2016-11-01

    Oxygen isotope ratios in tree rings (δ18OTR) from northern Bolivia record local precipitation δ18O and correlate strongly with Amazon basin-wide rainfall. While this is encouraging evidence that δ18OTR can be used for paleoclimate reconstructions, it remains unclear whether variation in δ18OTR is truly driven by within-basin processes, thus recording Amazon climate directly, or if the isotope signal may already be imprinted on incoming vapor, perhaps reflecting a pan-tropical climate signal. We use atmospheric back trajectories combined with satellite observations of precipitation, together with water vapor transport analysis to show that δ18OTR in Bolivia are indeed controlled by basin-intrinsic processes, with rainout over the basin the most important factor. Furthermore, interannual variation in basin-wide precipitation and atmospheric circulation are both shown to affect δ18OTR. These findings suggest δ18OTR can be reliably used to reconstruct Amazon precipitation and have implications for the interpretation of other paleoproxy records from the Amazon basin.

  15. The Spatial Coherence of Interannual Temperature Variations in the Antarctic Peninsula

    NASA Technical Reports Server (NTRS)

    King, John C.; Comiso, Josefino C.; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    Over 50 years of observations from climate stations on the west coast of the Antarctic Peninsula show that this is a region of extreme interannual variability in near-surface temperatures. The region has also experienced more rapid warming than any other part of the Southern Hemisphere. In this paper we use a new dataset of satellite-derived surface temperatures to define the extent of the region of extreme variability more clearly than was possible using the sparse station data. The region in which satellite surface temperatures correlate strongly with west Peninsula station temperatures is found to be quite small and is largely confined to the seas just west of the Peninsula, with a northward and eastward extension into the Scotia Sea and a southward extension onto the western slopes of Palmer Land. Correlation of Peninsula surface temperatures with surface temperatures over the rest of continental Antarctica is poor confirming that the west Peninsula is in a different climate regime. The analysis has been used to identify sites where ice core proxy records might be representative of variations on the west coast of the Peninsula. Of the five existing core sites examined, only one is likely to provide a representative record for the west coast.

  16. Interannual Modulation of Subtropical Atlantic Boreal Summer Dust Variability by ENSO

    SciTech Connect

    DeFlorio, Mike; Goodwin, Ian D.; Cayan, Dan; Miller, Arthur J.; Ghan, Steven J.; Pierce, David; Russell, Lynn M.; Singh, Balwinder

    2016-01-01

    Dust variability in the climate system has been studied for several decades, yet there remains an incomplete understanding of the dynamical mechanisms controlling interannual and decadal variations in dust transport. The sparseness of multi-year observational datasets has limited our understanding of the relationship between climate variations and atmospheric dust. We use available observations and a century-length fully coupled Community Earth System Model (CESM) simulation to show that the El Niño- Southern Oscillation (ENSO) exerts a control on North African dust transport during boreal summer. In CESM, this relationship is stronger over the dusty tropical North Atlantic than near Barbados, one of the few sites having a multi-decadal observed record. During strong La Niña summers in CESM, a statistically significant increase in lower tropospheric easterly wind is associated with an increase in North African dust transport over the Atlantic. Barbados dust and Pacific SST variability are only weakly correlated in both observations and CESM, suggesting that other processes are controlling the crossbasin variability of dust. We also use our CESM simulation to show that the relationship between downstream North African dust transport and ENSO fluctuates on multidecadal timescales and may be modulated by the North Atlantic Oscillation (NAO). Our findings indicate that existing observations of dust over the tropical North Atlantic are not extensive enough to completely describe the variability of dust and dust transport, and demonstrate the importance of global models to supplement and interpret observational records.

  17. Studies of Seasonal to Interannual Ocean Salinity Variations With Satellite Data

    NASA Astrophysics Data System (ADS)

    Lagerloef, Gary

    2016-04-01

    An important scientific goal for satellite salinity observations is to document oceanic climate trends and their link to changes in the water cycle. This study is a preliminary examination of multi-year sea surface salinity (SSS) trends from analyses of Aquarius, SMOS and SMAP data, years 2010-2015 to assess the feasibility of monitoring such trends from the current satellite salinity data sets. Orthogonal mode analyses are evaluated to resolve trend modes among other seasonal and interannual variability patterns. The dominant trend is isolated in the western tropical Pacific and evidently associated with ENSO evolution during these years. The results signify that resolving secular climate trends in the global water cycle will require extended decadal or longer satellite salinity time series. Recognizing that the Aquarius data record is now finite (Sep 2011 through May 2015) due to the mission failure in early June 2015, I will conclude with a summary of the status and disposition of the Aquarius data record and its value as a reference for salinity measurement continuity with both SMOS and SMAP satellite salinity measurements.

  18. Relationship between the interannual variability of satellite-observed fires and sea surface temperature anomalies

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Randerson, J. T.; Morton, D. C.; DeFries, R. S.; Collatz, G. J.; Kasibhatla, P. S.; Giglio, L.; Jin, Y.; Marlier, M.

    2011-12-01

    Fire is a worldwide phenomenon that occurs in multiple biomes and regions, and has large impacts on ecosystems, air quality, and global climate. High fire years are often associated with an extended dry season and anomalously low levels of precipitation. Sea surface temperatures (SST) may regulate the precipitation variability on land through teleconnections. Here we investigated the relationship between year-to-year changes in satellite-derived estimates of fire activity and SST anomalies. Using South America as an example, we demonstrated an approach to predict regional annual fire season severity with 3-5 month lead times. We found that the Oceanic Niño Index (ONI) was correlated with interannual fire activity in the eastern Amazon whereas the Atlantic Multidecadal Oscillation (AMO) index was more closely linked with fires in the southern and southwestern Amazon. We then extended this approach to examine the relationship between fire occurrences and SSTs for other important fire regions, using SST anomalies from different regions within the Pacific, Atlantic, and Indian Oceans. We determined regions where SST changes had significant impacts on the annual fire season severity, as well as the optimal lead times of fire prediction for each region. This study will be of use in several different ways to inform mitigation and adaptation strategies related to climate change.

  19. Spatial patterns of ENSO's interannual influences on lilacs vary with time and periodicity

    NASA Astrophysics Data System (ADS)

    Fu, Congsheng; Ji, Zhenming; Wei, Zhongwang

    2017-04-01

    The influences of solar activity and large-scale climate modes (e.g. the El Niño/Southern Oscillation - 'ENSO') have been identified in many geophysical processes. However, few studies have attempted to investigate the frequency characteristics and corresponding spatial patterns of the interannual influence of either solar activity or large-scale climate modes on phenology. In this study, the influences of solar activity (represented by sunspot number 'SSN') and ENSO on the first leaf and bloom dates of the common lilac and cloned lilac in the United States were analyzed for time series spanning ≥ 33 years using the wavelet coherence method. The spatial patterns in the influence of ENSO on the first leaf and bloom dates were investigated for different times and periodicities, using time series of ≥ 20 years. The combined influences of solar activity and ENSO on the first leaf and bloom dates of lilacs were identified for most of the stations with records spanning ≥ 33 years. In the 11-year band, both increasing solar activity (SSN) and El Niño caused delays in the first leaf and bloom events of the cloned lilac during the 1980s in the northeastern United States. The frequency characteristics and the spatial patterns of the influence of ENSO on the first leaf day and first bloom day were essentially consistent, and such spatial patterns vary with time and periodicity.

  20. Recurrent Fever in Children

    PubMed Central

    Torreggiani, Sofia; Filocamo, Giovanni; Esposito, Susanna

    2016-01-01

    Children presenting with recurrent fever may represent a diagnostic challenge. After excluding the most common etiologies, which include the consecutive occurrence of independent uncomplicated infections, a wide range of possible causes are considered. This article summarizes infectious and noninfectious causes of recurrent fever in pediatric patients. We highlight that, when investigating recurrent fever, it is important to consider age at onset, family history, duration of febrile episodes, length of interval between episodes, associated symptoms and response to treatment. Additionally, information regarding travel history and exposure to animals is helpful, especially with regard to infections. With the exclusion of repeated independent uncomplicated infections, many infective causes of recurrent fever are relatively rare in Western countries; therefore, clinicians should be attuned to suggestive case history data. It is important to rule out the possibility of an infectious process or a malignancy, in particular, if steroid therapy is being considered. After excluding an infectious or neoplastic etiology, immune-mediated and autoinflammatory diseases should be taken into consideration. Together with case history data, a careful physical exam during and between febrile episodes may give useful clues and guide laboratory investigations. However, despite a thorough evaluation, a recurrent fever may remain unexplained. A watchful follow-up is thus mandatory because new signs and symptoms may appear over time. PMID:27023528

  1. Recurrent Fever in Children.

    PubMed

    Torreggiani, Sofia; Filocamo, Giovanni; Esposito, Susanna

    2016-03-25

    Children presenting with recurrent fever may represent a diagnostic challenge. After excluding the most common etiologies, which include the consecutive occurrence of independent uncomplicated infections, a wide range of possible causes are considered. This article summarizes infectious and noninfectious causes of recurrent fever in pediatric patients. We highlight that, when investigating recurrent fever, it is important to consider age at onset, family history, duration of febrile episodes, length of interval between episodes, associated symptoms and response to treatment. Additionally, information regarding travel history and exposure to animals is helpful, especially with regard to infections. With the exclusion of repeated independent uncomplicated infections, many infective causes of recurrent fever are relatively rare in Western countries; therefore, clinicians should be attuned to suggestive case history data. It is important to rule out the possibility of an infectious process or a malignancy, in particular, if steroid therapy is being considered. After excluding an infectious or neoplastic etiology, immune-mediated and autoinflammatory diseases should be taken into consideration. Together with case history data, a careful physical exam during and between febrile episodes may give useful clues and guide laboratory investigations. However, despite a thorough evaluation, a recurrent fever may remain unexplained. A watchful follow-up is thus mandatory because new signs and symptoms may appear over time.

  2. 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

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

    NASA Astrophysics Data System (ADS)

    Yanto; Rajagopalan, Balaji; Zagona, Edith

    2016-11-01

    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 Anglia 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.

  4. Recurrent wheezing in children

    PubMed Central

    Piazza, Michele; Piacentini, Giorgio

    2016-01-01

    Recurrent wheezing have a significant morbidity and it’s estimated that about one third of school-age children manifest the symptom during the first 5 years of life. Proper identification of children at risk of developing asthma at school age may predict long-term outcomes and improve treatment and preventive approach, but the possibility to identify these children at preschool age remains limited. For many years authors focused their studies to identify early children with recurrent wheezing at risk to develop asthma at school age. Different phenotypes have been proposed for a more precise characterization and a personalized plan of treatment. The main criticism concerns the inability to define stable phenotypes with the risk of overestimating or underestimating the characteristics of symptoms in these children. The aim of this review is to report the recent developments on the diagnosis and treatment of recurrent paediatric wheezing. PMID:26835404

  5. Recurrence of angular cheilitis.

    PubMed

    Ohman, S C; Jontell, M; Dahlen, G

    1988-08-01

    The incidence of recurrence of angular cheilitis following a successful antimicrobial treatment was studied in 48 patients. Clinical assessments including a microbial examination were carried out 8 months and 5 yr after termination of treatment. Eighty percent of the patients reported recurrence of their angular cheilitis on one or more occasions during the observation period. Patients with cutaneous disorders associated with dry skin or intraoral leukoplakia had an increased incidence of recrudescence. Neither the presence of denture stomatitis nor the type of microorganisms isolated from the original lesions of angular cheilitis, i.e. Candida albicans and/or Staphylococcus aureus, were associated with the number of recurrences. The present observations indicate that treatment of the majority of patients with angular cheilitis should be considered in a longer perspective than previously supposed, due to the short lasting therapeutic effects of the antimicrobial therapy.

  6. Interannual variability of Net Ecosystem CO2 Exchange and its component fluxes in a subalpine Mediterranean ecosystem (SE Spain)

    NASA Astrophysics Data System (ADS)

    Chamizo, Sonia; Serrano-Ortiz, Penélope; Sánchez-Cañete, Enrique P.; Domingo, Francisco; Arnau-Rosalén, Eva; Oyonarte, Cecilio; Pérez-Priego, Óscar; López-Ballesteros, Ana; Kowalski, Andrew S.

    2015-04-01

    Recent decades under climate change have seen increasing interest in quantifying the carbon (C) balance of different terrestrial ecosystems, and their behavior as sources or sinks of C. Both CO2 exchange between terrestrial ecosystems and the atmosphere and identification of its drivers are key to understanding land-surface feedbacks to climate change. The eddy covariance (EC) technique allows measurements of net ecosystem C exchange (NEE) from short to long time scales. In addition, flux partitioning models can extract the components of net CO2 fluxes, including both biological processes of photosynthesis or gross primary production (GPP) and respiration (Reco), and also abiotic drivers like subsoil CO2 ventilation (VE), which is of particular relevance in semiarid environments. The importance of abiotic processes together with the strong interannual variability of precipitation, which strongly affects CO2 fluxes, complicates the accurate characterization of the C balance in semiarid landscapes. In this study, we examine 10 years of interannual variability of NEE and its components at a subalpine karstic plateau, El Llano de los Juanes, in the Sierra de Gádor (Almería, SE Spain). Results show annual NEE ranging from 55 g C m-2 (net emission) to -54 g C m-2 (net uptake). Among C flux components, GPP was the greatest contributing 42-57% of summed component magnitudes, while contributions by Reco and VE ranged from 27 to 46% and from 3 to 18%, respectively. Annual precipitation during the studied period exhibited high interannual variability, ranging from 210 mm to 1374 mm. Annual precipitation explained 50% of the variance in Reco, 59% of that in GPP, and 56% for VE. While Reco and GPP were positively correlated with annual precipitation (correlation coefficient, R, of 0.71 and 0.77, respectively), VE showed negative correlation with this driver (R = -0.74). During the driest year (2004-2005), annual GPP and Reco reached their lowest values, while contribution of

  7. Recurrent aphthous stomatitis.

    PubMed

    Akintoye, Sunday O; Greenberg, Martin S

    2014-04-01

    Recurrent aphthous stomatitis (RAS) is the most common ulcerative disease affecting the oral mucosa. RAS occurs mostly in healthy individuals and has an atypical clinical presentation in immunocompromised individuals. The etiology of RAS is still unknown, but several local, systemic, immunologic, genetic, allergic, nutritional, and microbial factors, as well as immunosuppressive drugs, have been proposed as causative agents. Clinical management of RAS using topical and systemic therapies is based on severity of symptoms and the frequency, size, and number of lesions. The goals of therapy are to decrease pain and ulcer size, promote healing, and decrease the frequency of recurrence.

  8. [Recurrent purulent bacterial meningoencephalitis].

    PubMed

    Janeczko, J; Pogorzelska, E; Lipowski, D; Przyjałkowski, W; Rzadkiewicz, E

    2001-01-01

    During the period of 25 years there were 55 patients treated in our Institute because of recurrent purulent bacterial meningoencephalitis(rpbme). This group consisted of 42 males (76%) and 13 (24%) females, the prevalent number (53%) of patients being under 21 years of age. The diagnosis of rpbme was based on the commonly accepted criteria and confirmed by the laboratory results of CSF examination. The cause of the recurrences was established considering the skull X-ray examination, CT and MRI. The evaluation of the clinical status was based on the Glasgow Coma Score (GCS). During the first hospitalisation, severe or critic clinical status was noted in 42 patients (76%) and moderate in 13 (24%). The subsequent recurrences were mostly moderate, rarely severe or mild. The number of recurrences varied from 1 to 9. During the first hospitalisation, the etiologic factor was detected in 39 patients (71%), i.e. Streptococcus pneumoniae in 28 (51%), Neisseria meningitidis in 8 (14%), Pseudomonas aeruginosa and Staphylococcus aureus in 2 and 1 patients respectively. In 37 patients (67%) rpbme developed following cranial trauma, in 18 cases (33%) with single or comminuted fractures of the anterior cranial fossa (in 4 cases accompanied by CSF nasal exsudate). In 4 it followed neurosurgical intervention, in 3 it accompanied recurrent purulent highmorities, in 1 case--after removal of the nasal polyps and subsequent CSF nasal exsudate, and in 1 patient with recurrent mastoiditis. In 6 cases (11%) the cause of the recurrences remained unelucidated. The clinical signs and symptoms, diagnostic difficulties and the causative treatment of rpbme are discussed. In the authors' opinion, surgical treatment of the communication between the CSF and the external environment prevents the recurrences and is the only successful way of treatment. Special attention is drawn to the great diagnostic value of CT and MRI. The use of other modern techniques, e.g. positron emission tomography (PET

  9. Serially recurrent osteoid osteoma.

    PubMed

    Sampath, Srihari C; Sampath, Srinath C; Rosenthal, Daniel I

    2015-06-01

    Osteoid osteoma is a relatively common, benign, painful tumor of bone. It is widely believed to run a course culminating in spontaneous regression. The tumor can usually be eliminated by excision or ablation, although it may recur locally. Although management has classically been surgical, thermocoagulation via percutaneously delivered radiofrequency energy has demonstrated excellent results, typically resulting in durable response following a single treatment. Here, we present an unusual case of serially recurrent pathologically proven pediatric osteoid osteoma, treated by radiofrequency ablation five times over the course of 11 years. Limitations of RF ablation of osteoid osteoma and possible factors predisposing to incomplete treatment or recurrence are discussed.

  10. Recurrent Aphthous Stomatitis

    PubMed Central

    Akintoye, Sunday O.; Greenberg, Martin S.

    2014-01-01

    Recurrent Aphthous Stomatitis (RAS) is the most common ulcerative disease affecting the oral mucosa. It occurs mostly in healthy individuals and has atypical clinical presentation in immunocompromised individuals. The etiology of RAS is still unknown, but several local, systemic, immunologic, genetic, allergic, nutritional, and microbial factors, as well as immunosuppressive drugs, have been proposed as causative agents. Clinical management of RAS is based on severity of symptoms, frequency, size and number of lesions using topical and systemic therapies. The goals of therapy are to decrease pain and ulcer size, promote healing and decrease frequency of recurrence. PMID:24655523

  11. Observations and simulations of climate forcings and feedbacks. Final report

    SciTech Connect

    Del Genio, A.D.

    1996-02-01

    The research conducted under this agreement sought to use available satellite data sets to document a variety of climate feedback processes by understanding the mechanisms of current climate variability (seasonal, interannual, temperature dependence). Comparisons with feedback processes operating in the GCM were performed to determine which aspects of the variability serve as the most reliable proxies for decadal climate change. This report focuses on three general areas of progress: upper troposphere water vapor, low cloud optical thickness, and tropical cumulus anvil clouds.

  12. Interannual Rainfall Variability in the Tropical Atlantic Region

    NASA Technical Reports Server (NTRS)

    Gu, Guojun

    2005-01-01

    Rainfall variability on seasonal and interannual-to-interdecadal time scales in the tropical Atlantic is quantified using a 25-year (1979-2003) monthly rainfall dataset from the Global Precipitation Climatology Project (GPCP). The ITCZ measured by monthly rainfall between 15-37.5 deg W attains its peak as moving to the northernmost latitude (4-10 deg N) during July-September in which the most total rainfall is observed in the tropical Atlantic basin (17.5 deg S-22.5 deg N, 15 deg-37.5 deg W); the ITCZ becomes weakest during January-February with the least total rainfall as it moves to the south. In contrast, rainfall variability on interannual to interdecadal time scales shows a quite different seasonal preference. The most intense interannual variability occurs during March-May when the ITCZ tends to be near the equator and becomes weaker. Significant, negative correlations between the ITCZ strength and latitude anomalies are observed during boreal spring and early summer. The ITCZ strength and total rainfall amount in the tropical Atlantic basin are significantly modulated by the Pacific El Nino and the Atlantic equatorial mode (or Atlantic Nino) particularly during boreal spring and summer; whereas the impact of the Atlantic interhemispheric mode is considerably weaker. Regarding the anomalous latitudes of the ITCZ, the influence can come from both local, i.e., the Atlantic interhemispheric and equatorial modes, and remote forcings, i. e., El Nino; however, a direct impact of El Nino on the latitudes of the ITCZ can only be found during April-July, not in winter and early spring in which the warmest SST anomalies are usually observed in the equatorial Pacific.

  13. Wood export varies among decadal, annual, seasonal, and daily scale hydrologic regimes in a large, Mediterranean climate, mountain river watershed

    NASA Astrophysics Data System (ADS)

    Senter, A. E.; Pasternack, G. B.; Piégay, H.; Vaughan, M. C.; Lehyan, J. S.

    2017-01-01

    The dynamics that move wood through and out of watersheds are complex and not yet fully understood. In this study, climatic conditions, hydrologic responses, and watershed processes were explored to better understand variations in wood export using aerial imagery, event-based video monitoring, and field measurements from the 1097 km2 mountainous Mediterranean climate North Yuba River, California, watershed and its reservoir near the downstream outlet. Over a 30-year study period, 1985-2014, volumetric estimates of annual wood export into the reservoir, available for a subset of years, were used to investigate watershed-scale wood export dynamics. Variations in annual peak discharge explained 79% of the variance in interannual wood export, with 84% of total observed wood export (ca. > 10,000 m3 of wood per event) delivered by three discharge events of 19-year, 21.5-year, and 60-year flood recurrence intervals. Continuous video monitoring conducted during snowmelt season periods in 2010 and 2011 yielded wood discharge observations at minima 15% of statistical bankfull flow, while maximum daily discharge explained 55% of observed daily wood piece variation. No statistically significant wood discharge differences were found in snowmelt season observations, likely because of domination of the hydrograph by diurnal pulses within the seasonal cycle. A conceptual model and functional framework are introduced in support of a watershed-scale explanation of wood export, transport, and storage processes applicable to large, Mediterranean-climate, mountain watershed settings.

  14. On Solving Linear Recurrences

    ERIC Educational Resources Information Center

    Dobbs, David E.

    2013-01-01

    A direct method is given for solving first-order linear recurrences with constant coefficients. The limiting value of that solution is studied as "n to infinity." This classroom note could serve as enrichment material for the typical introductory course on discrete mathematics that follows a calculus course.

  15. Recurrent gallstone ileus.

    PubMed

    Hayes, Nicolas; Saha, Sanjoy

    2012-11-01

    Mechanical small bowel obstructions caused by gallstones account for 1% to 3% of cases. In these patients, 80% to 90% of residual gallstones in these patients will pass through a remaining fistula without consequence. Recurrent gallstone ileus has been reported in 5% of patients. We report the case of a woman, aged 72 years, who presented with mechanical small bowel obstruction caused by gallstone ileus. After successful surgical therapy for gallstone ileus, the patient's symptoms recurred, and she was diagnosed with recurrent gallstone ileus requiring a repeat operation. While management of gallstone ileus can be achieved through a single-stage operation including enterolithotomy and cholecystectomy with repair of biliary-enteric fistula or by enterolithotomy alone, the literature supports enterolithotomy alone as the treatment of choice for gallstone ileus due to decreased mortality and morbidity. However, the latter approach does not obviate potential recurrence. We present this case of recurrent gallstone ileus to elucidate and review the pathogenesis, presentation, diagnosis, and consensus recommendations regarding management of this disorder.

  16. Lung Cancer Indicators Recurrence

    Cancer.gov

    This study describes prognostic factors for lung cancer spread and recurrence, as well as subsequent risk of death from the disease. The investigators observed that regardless of cancer stage, grade, or type of lung cancer, patients in the study were more

  17. Meteorological influences on the interannual variability of meningitis incidence in northwest Nigeria.

    NASA Astrophysics Data System (ADS)

    Abdussalam, Auwal; Monaghan, Andrew; Dukic, Vanja; Hayden, Mary; Hopson, Thomas; Leckebusch, Gregor

    2013-04-01

    Northwest Nigeria is a region with high risk of bacterial meningitis. Since the first documented epidemic of meningitis in Nigeria in 1905, the disease has been endemic in the northern part of the country, with epidemics occurring regularly. In this study we examine the influence of climate on the interannual variability of meningitis incidence and epidemics. Monthly aggregate counts of clinically confirmed hospital-reported cases of meningitis were collected in northwest Nigeria for the 22-year period spanning 1990-2011. Several generalized linear statistical models were fit to the monthly meningitis counts, including generalized additive models. Explanatory variables included monthly records of temperatures, humidity, rainfall, wind speed, sunshine and dustiness from weather stations nearest to the hospitals, and a time series of polysaccharide vaccination efficacy. The effects of other confounding factors -- i.e., mainly non-climatic factors for which records were not available -- were estimated as a smooth, monthly-varying function of time in the generalized additive models. Results reveal that the most important explanatory climatic variables are mean maximum monthly temperature, relative humidity and dustiness. Accounting for confounding factors (e.g., social processes) in the generalized additive models explains more of the year-to-year variation of meningococcal disease compared to those generalized linear models that do not account for such factors. Promising results from several models that included only explanatory variables that preceded the meningitis case data by 1-month suggest there may be potential for prediction of meningitis in northwest Nigeria to aid decision makers on this time scale.

  18. 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

  19. Interannual covariability between actual evapotranspiration and PAL and GIMMS NDVIs of northern Asia

    USGS Publications Warehouse

    Suzuki, Rikie; Masuda, Kooiti; Dye, Dennis G.

    2007-01-01

    This study examined the covariability between interannual changes in the normalized difference vegetation index (NDVI) and actual evapotranspiration (ET). To reduce possible uncertainty in the NDVI time series, two NDVI datasets derived from Pathfinder AVHRR Land (PAL) data and the Global Inventory Monitoring and Modeling Studies (GIMMS) group were used. Analyses were conducted using data over northern Asia from 1982 to 2000. Interannual changes over 19 years in the PAL-NDVI and GIMMS-NDVI were compared with interannual changes in ET estimated from model-assimilated atmospheric data and gridded precipitation data. For both NDVI datasets, the annual maximum correlation with ET occurred in June, which is the beginning of the vegetation growing season. The PAL and GIMMS datasets showed a significant, positive correlation between interannual changes in the NDVI and ET over most of the vegetated land area in June. These results suggest that interannual changes in vegetation activity predominantly control interannual changes in ET in June. Based on analyses of interannual changes in temperature, precipitation, and the NDVI in June, the study area can be roughly divided into two regions, the warmth-dominated northernmost region and the wetness-dominated southern region, indicating that interannual changes in vegetation and the resultant interannual changes in ET are controlled by warmth and wetness in these two regions, respectively.

  20. Southern Hemisphere carbon monoxide interannual variability observed by Terra/Measurement of Pollution in the Troposphere (MOPITT)

    NASA Astrophysics Data System (ADS)

    Edwards, D. P.; PéTron, G.; Novelli, P. C.; Emmons, L. K.; Gille, J. C.; Drummond, J. R.

    2006-08-01

    Biomass burning is an annual occurrence in the tropical Southern Hemisphere (SH) and represents a major source of regional pollution. Vegetation fires emit carbon monoxide (CO), which because of its medium lifetime is an excellent tracer of tropospheric transport. CO is also one of the few tropospheric trace gases currently observed from satellite, and this provides long-term global measurements. In this paper, we use the 5-year CO data record from the Measurement of Pollution in the Troposphere (MOPITT) instrument to examine the interannual variability of the SH CO loading and show how this relates to climate conditions which determine the intensity of fire sources. The MOPITT observations show an annual austral springtime peak in the SH zonal CO loading each year with dry season biomass burning emissions in South America, southern Africa, the maritime continent, and northwestern Australia. Although fires in southern Africa and South America typically produce the greatest amount of CO, the most significant interannual variation is due to varying fire activity and emissions from the maritime continent and northern Australia. We find that this variation in turn correlates well with the El Niño-Southern Oscillation precipitation index. Between 2000 and 2005, emissions were greatest in late 2002, and an inverse modeling of the MOPITT data using the Model of Ozone Research in the Troposphere (MOZART) chemical transport model estimates the Southeast Asia regional fire source for the year August 2002 to September 2003 to be 52 Tg CO. Comparison of the MOPITT retrievals and NOAA surface network measurements indicate that the latter do not fully capture the interannual variability or the seasonal range of the CO zonal average concentration because of biases associated with atmospheric and geographic sampling.

  1. Atmospheric radiative feedbacks associated with transient climate change and climate variability

    NASA Astrophysics Data System (ADS)

    Colman, Robert A.; Power, Scott B.

    2010-06-01

    climate change. Surface albedo feedback is, however, slightly stronger under interannual variability—partly due to regions of extremely weak, or even negative, feedback over Antarctic sea ice in the transient experiment. Both long and shortwave global cloud feedbacks are essentially zero on interannual timescales, with the shortwave term also being very weak under climate change, although cloud fraction and optical property components show correlation with global temperature both under interannual variability and transient climate change. The results of this modelling study, although for a single model only, suggest that the analogues provided by interannual variability may provide some useful pointers to some aspects of climate change feedback strength, particularly for water vapour and surface albedo, but that structural differences will need to be heeded in such an analysis.

  2. Effects of seasonal and inter-annual land cover changes on the hydrology of the Upper Ganges basin, India

    NASA Astrophysics Data System (ADS)

    Tsarouchi, G.; Mijic, A.; Buytaert, W.

    2013-12-01

    In recent decades India has undergone substantial environmental change. The expansion of agricultural land area to meet the demand of a rapidly increasing population and the increasing intensification of groundwater extractions have led to an alarming drop in the water table levels. The recent floods over northern India have raised concerns about how the regional climate variations and human induced changes in landscape are influencing the temporal dynamics of climate-surface-groundwater interactions. Earlier work by the authors developed high-resolution land cover maps for northern India, based on satellite imagery, for the years 1984, 1998 and 2010. These maps were used to drive the distributed version of the land surface model JULES in order to investigate the impact of inter-annual land cover changes in the hydrology of the Upper Ganges (UG) river basin in India. However, JULES in its current version does not simulate crop growth. Since 60% of the study area is occupied by agriculture, the model was improved with routines that allow for dynamic representation of crop growth. The parametrization was done for the two main crops of the UG basin (wheat and rice), allowing for 2 cropping seasons per year. The impact of seasonal and inter-annual land cover changes was investigated by calculating variations in hydrological components such as stream flow, evapotranspiration and soil moisture. The results show that the seasonal cycle is changing a lot when crop growth is taken into account, whereas annual fluxes do not change much. The dynamic coupling of land-surface schemes and crop models is an essential step toward the analysis of future changes of water resources in India caused by climate change, land use change, and potential interactions between both. This is a prerequisite for constructing decision support tools for regional land-use planning and management.

  3. Vole and lemming activity observed from space: trophic cascade driven interannual vegetation cycles at a regional scale

    NASA Astrophysics Data System (ADS)

    Olofsson, J.; Tömmervik, H.; Callaghan, T.

    2011-12-01

    Present global warming requires an understanding of the factors controlling plant biomass and production. The extent to which plant biomass and production is controlled by bottom-up drivers like climate, nutrient and water availability and by top down drivers like herbivory and diseases in terrestrial systems is still under debate. By annually recording plant biomass and community composition in grazed control plots and in herbivore-free exclosures, at twelve sites in a subarctic ecosystem, we were able to show that the regular interannual density fluctuations of voles and lemmings drive synchronous interannual fluctuations in biomass of ground and field layer vegetation (Fig. 1). The effect of the rodents on the vegetation is so strong that it can be detected in fluctuations of NDVI estimates from satellite images of a 20km2 area of tundra heathland. Plant biomass in the field layer was between 9 and 23% lower and NDVI was between 1 % and 25 % lower, the year after a vole peak than the year before. The synchronous decline of most dominant shrub species in the winter following an autumn rodent peak drives the fluctuations in total plant biomass. That the rodent cycles are detectable from satellite images, despite the wide range of abiotic, biotic and antropogenic forces that influence the vegetation, shows that the effects of rodents are strong enough to influence how primary production, carbon storage and biodiversity will respond to ongoing and future climate change. Changes of the rodent cycle may thus cause cascading changes of ecosystem functioning in a changing climate.

  4. Influence of the Southern Annular Mode on the circumpolar ocean circulation on timescales from subseasonal to interannual

    NASA Astrophysics Data System (ADS)

    Meredith, M. P.; Hughes, C. W.; Woodworth, P. L.

    2004-05-01

    The Southern Ocean surrounding Antarctica is unique in being zonally unbounded, and forms a link between the Atlantic, Pacific and Indian Oceans that is important to the global oceanic thermohaline circulation and hence climate. Consequently there is great interest in measuring and understanding changes in ocean transport around Antarctica, although conventional techniques such as hydrographic sections and current meter arrays have limitations due to the complexity of the current systems. We will demonstrate that data from coastal tide gauges and Bottom Pressure Recorders (BPRs) deployed around Antarctica have great utility in monitoring the genuine circumpolar transport variability. The primary driving mechanism for the transport changes is variability in circumpolar eastward winds associated with the Southern Annular Mode (SAM, also called the Antarctic Oscillation). High levels of coherence are observed in the sea level data from around Antarctica at subseasonal frequencies, testifying to the circumpolar response to the forcing. At these frequencies, the transport changes are highly barotropic (depth independent), thus the signal of the SAM is seen to extend completely to the deep ocean floor around Antarctica. The SAM has been observed to be undergoing significant changes in the past 30 years, manifested via changes in its seasonality. These changes to the seasonal signal are also present in BPR data collected near Antarctica, and suggest a possible mechanism whereby large-scale atmospheric climate variability can directly influence ocean circulation. At interannual timescales, significant correlation is observed between the SAM and Antarctic sea level measured at Faraday (Vernadsky), despite the transport variability presumably having a significant baroclinic (depth dependent) component at these frequencies. This further suggests sensitivity of the ocean circulation to large-scale high-latitude climate variability, and presents a possible low-cost method for

  5. Geodetic secular velocity errors due to interannual surface loading deformation

    NASA Astrophysics Data System (ADS)

    Santamaría-Gómez, Alvaro; Mémin, Anthony

    2015-08-01

    Geodetic vertical velocities derived from data as short as 3 yr are often assumed to be representative of linear deformation over past decades to millennia. We use two decades of surface loading deformation predictions due to variations of atmospheric, oceanic and continental water mass to assess the effect on secular velocities estimated from short time-series. The interannual deformation is time-correlated at most locations over the globe, with the level of correlation depending mostly on the chosen continental water model. Using the most conservative loading model and 5-yr-long time-series, we found median vertical velocity errors of 0.5 mm yr-1 over the continents (0.3 mm yr-1 globally), exceeding 1 mm yr-1 in regions around the southern Tropic. Horizontal velocity errors were seven times smaller. Unless an accurate loading model is available, a decade of continuous data is required in these regions to mitigate the impact of the interannual loading deformation on secular velocities.

  6. Performance of the WRF model to simulate the seasonal and interannual variability of hydrometeorological variables in East Africa: a case study for the Tana River basin in Kenya

    NASA Astrophysics Data System (ADS)

    Kerandi, Noah Misati; Laux, Patrick; Arnault, Joel; Kunstmann, Harald

    2016-08-01

    This study investigates the ability of the regional climate model Weather Research and Forecasting (WRF) in simulating the seasonal and interannual variability of hydrometeorological variables in the Tana River basin (TRB) in Kenya, East Africa. The impact of two different land use classifications, i.e., the Moderate Resolution Imaging Spectroradiometer (MODIS) and the US Geological Survey (USGS) at two horizontal resolutions (50 and 25 km) is investigated. Simulated precipitation and temperature for the period 2011-2014 are compared with Tropical Rainfall Measuring Mission (TRMM), Climate Research Unit (CRU), and station data. The ability of Tropical Rainfall Measuring Mission (TRMM) and Climate Research Unit (CRU) data in reproducing in situ observation in the TRB is analyzed. All considered WRF simulations capture well the annual as well as the interannual and spatial distribution of precipitation in the TRB according to station data and the TRMM estimates. Our results demonstrate that the increase of horizontal resolution from 50 to 25 km, together with the use of the MODIS land use classification, significantly improves the precipitation results. In the case of temperature, spatial patterns and seasonal cycle are well reproduced, although there is a systematic cold bias with respect to both station and CRU data. Our results contribute to the identification of suitable and regionally adapted regional climate models (RCMs) for East Africa.

  7. 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

  8. Impacts of fire emissions and transport pathways on the interannual variation of CO in the tropical upper troposphere

    NASA Astrophysics Data System (ADS)

    Huang, L.; Fu, R.; Jiang, J. H.

    2013-10-01

    Carbon monoxide (CO) is an important tracer to study the transport of fire-generated pollutants from the surface to the upper troposphere (UT). This study analyzed the relative importance of fire emission, convection and climate conditions on the interannual variation of CO in the tropical UT, by using satellite observations, reanalysis data and transport pathway auto-identification method developed in our previous study. Empirical orthogonal function (EOF) and singular value decomposition (SVD) methods are used to identify the dominant modes of CO interannual variation in the tropical UT and factors that are related to these modes. Results show that the leading EOF mode is dominated by CO anomalies over Indonesia related to El Niño-Southern Oscillation (ENSO). This is consistent with previous findings by directly evaluating CO anomaly field. Transport pathway analysis suggests that the differences of UT CO between different ENSO types over the tropical continents are mainly dominated by the "local convection" pathway, especially the average CO transported by this pathway. The relative frequency of the "advection within the lower troposphere (LT) followed by convective vertical transport" pathway appears to be responsible only for the UT CO differences over the west-central Pacific between El Niño and La Niña years.

  9. Impacts of Fire Emissions and Transport Pathways on the Interannual Variation of CO in the Tropical Upper Troposphere

    NASA Astrophysics Data System (ADS)

    Huang, L.; Fu, R.; Jiang, J. H.

    2013-12-01

    Carbon monoxide (CO) is an important tracer to study the transport of fire-generated pollutants from the surface to the upper troposphere (UT). This study analyzed the relative importance of fire emission, convection and climate conditions on the interannual variation of CO in the tropical UT, by using satellite observations, reanalysis data and transport pathway auto-identification method developed in our previous study. Empirical orthogonal function (EOF) and singular value decomposition (SVD) methods are used to identify the dominant modes of CO interannual variation in the tropical UT and factors that are related to these modes. Results show that the leading EOF mode is dominated by CO anomalies over Indonesia related to El Niño-Southern Oscillation (ENSO). This is consistent with previous findings by directly evaluate CO anomaly field. Transport pathway analysis suggests that the differences of UT CO between different ENSO types over the tropical continents are mainly dominated by the 'local convection' pathway, especially the average CO transported by this pathway. The relative frequency of the 'advection within the lower troposphere (LT) followed by convective vertical transport' pathway appears to be responsible only for the UT CO differences over the west-central Pacific between El Niño and La Niña years.

  10. 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.

  11. Biophysical controls on interannual variability in ecosystem-scale CO2 and CH4 exchange in a California rice paddy

    NASA Astrophysics Data System (ADS)

    Knox, Sara Helen; Matthes, Jaclyn Hatala; Sturtevant, Cove; Oikawa, Patricia Y.; Verfaillie, Joseph; Baldocchi, Dennis

    2016-03-01

    We present 6.5 years of eddy covariance measurements of fluxes of methane (FCH4) and carbon dioxide (FCO2) from a flooded rice paddy in Northern California, USA. A pronounced warming trend throughout the study associated with drought and record high temperatures strongly influenced carbon (C) budgets and provided insights into biophysical controls of FCO2 and FCH4. Wavelet analysis indicated that photosynthesis (gross ecosystem production, GEP) induced the diel pattern in FCH4, but soil temperature (Ts) modulated its amplitude. Forward stepwise linear models and neural networking modeling were used to assess the variables regulating seasonal FCH4. As expected due to their competence in modeling nonlinear relationships, neural network models explained considerably more of the variance in daily average FCH4 than linear models. During the growing season, GEP and water levels typically explained most of the variance in daily average FCH4. However, Ts explained much of the interannual variability in annual and growing season CH4 sums. Higher Ts also increased the annual and growing season ratio of FCH4 to GEP. The observation that the FCH4 to GEP ratio scales predictably with Ts may help improve global estimates of FCH4 from rice agriculture. Additionally, Ts strongly influenced ecosystem respiration, resulting in large interannual variability in the net C budget at the paddy, emphasizing the need for long-term measurements particularly under changing climatic conditions.

  12. Chronic recurrent multifocal osteomyelitis.

    PubMed

    Jurik, Anne Grethe

    2004-09-01

    Chronic recurrent multifocal osteomyelitis (CRMO) is a clinical entity distinct from bacterial osteomyelitis. It occurs mainly in children and adolescents and is characterized by a prolonged, fluctuating course with recurrent episodes of pain occurring over several years. CRMO is often multifocal and most often seen in tubular bones, the clavicle, and less frequently the spine and pelvic bones; other locations are rare. The radiographic appearance suggests subacute or chronic osteomyelitis. Histopathological and laboratory findings are nonspecific and bacterial culture is usually negative. CRMO is often diagnosed by exclusion of the two main differential diagnoses--bacterial infections and tumor--by assessing for a characteristic course and the findings by conventional radiography, if necessary supplemented by scintigraphy and/or magnetic resonance imaging (MRI). The MRI appearance of CRMO lesions in tubular bones and the spine is often rather characteristic and support the diagnosis. It is important to diagnose CRMO to avoid unnecessary diagnostic procedures and initiate an appropriate therapy.

  13. Chronic recurrent multifocal osteomyelitis.

    PubMed

    Costa-Reis, Patrícia; Sullivan, Kathleen E

    2013-08-01

    Chronic recurrent multifocal osteomyelitis is a rare auto-inflammatory condition that primarily affects children and adolescents. It presents with recurrent episodes of pain related to the presence of foci of sterile bone inflammation. The long bones of the lower extremities are more frequently affected and the spine can also be involved. Imaging studies, including whole-body magnetic resonance, are important for diagnosis and detection of asymptomatic lesions. Bone biopsies may be necessary to exclude other diseases, including malignancy and infections. Non-steroidal anti-inflammatory drugs cause relief of symptoms in the majority of cases. Bisphosphonates and TNF-α blockers are alternatives for patients who do not respond or who have spinal involvement.

  14. Treatment of recurrent concussion.

    PubMed

    McCrory, Paul

    2002-02-01

    The management of an athlete with recurrent concussions, whether persistently symptomatic or not, remains anecdotal. Currently, there are no evidence-based guidelines upon which a team physician can advise the athlete. All doctors involved in athlete care need to be aware of the potential for medicolegal problems if athletes are inappropriately returned to sport prematurely or, in the case of professional athletes, held out of sport or retired on the basis of nonscientific recommendations. This paper discusses such issues.

  15. Chronic recurrent multifocal osteomyelitis.

    PubMed

    Wedman, Jan; van Weissenbruch, Ranny

    2005-01-01

    We report what is, to our best knowledge, the first case of chronic recurrent multifocal osteomyelitis (CRMO) in which the frontal and sphenoid bones were involved. Characterized by a prolonged and fluctuating course of osteomyelitis at different sites, CRMO is self-limited, although sequelae can occur. The diagnosis is one of exclusion. It is important to publish cases like this, because the recognition of CRMO can prevent aggressive surgical and medical treatment.

  16. [Chronic recurrent multifocal osteomyelitis].

    PubMed

    Király, Balázs; Feith, Sándor; Barta, Miklós; Oroszlán, György

    2003-12-21

    The chronic recurrent multifocal osteomyelitis has been reported very rarely in the literature. However, its significance must be emphasized, because it is a spontaneously healing, benign disease, as compared to the classical forms of osteomyelitis. It leaves behind almost no residual symptoms, and many operations, long antimicrobial therapy may be avoided by diagnosing it. In this case report the authors provide the review of the disease through the history of a 9-year-old boy.

  17. Quantifying Interannual Variability for Photovoltaic Systems in PVWatts

    SciTech Connect

    Ryberg, David Severin; Freeman, Janine; Blair, Nate

    2015-10-01

    The National Renewable Energy Laboratory's (NREL's) PVWatts is a relatively simple tool used by industry and individuals alike to easily estimate the amount of energy a photovoltaic (PV) system will produce throughout the course of a typical year. PVWatts Version 5 has previously been shown to be able to reasonably represent an operating system's output when provided with concurrent weather data, however this type of data is not available when estimating system output during future time frames. For this purpose PVWatts uses weather data from typical meteorological year (TMY) datasets which are available on the NREL website. The TMY files represent a statistically 'typical' year which by definition excludes anomalous weather patterns and as a result may not provide sufficient quantification of project risk to the financial community. It was therefore desired to quantify the interannual variability associated with TMY files in order to improve the understanding of risk associated with these projects. To begin to understand the interannual variability of a PV project, we simulated two archetypal PV system designs, which are common in the PV industry, in PVWatts using the NSRDB's 1961-1990 historical dataset. This dataset contains measured hourly weather data and spans the thirty years from 1961-1990 for 239 locations in the United States. To note, this historical dataset was used to compose the TMY2 dataset. Using the results of these simulations we computed several statistical metrics which may be of interest to the financial community and normalized the results with respect to the TMY energy prediction at each location, so that these results could be easily translated to similar systems. This report briefly describes the simulation process used and the statistical methodology employed for this project, but otherwise focuses mainly on a sample of our results. A short discussion of these results is also provided. It is our hope that this quantification of the

  18. The Ob Estuary (Kara Sea) Coastal Dynamics Interannual Variability Assessment

    NASA Astrophysics Data System (ADS)

    Kopa-Ovdienko, N.; Volobueva, N.; Ogorodov, S.

    2012-04-01

    There are several promising gas fields in the Ob Estuary. For their development comprehensive research, including coastal dynamics assessment, is required. To estimate current and speak about future coastal dynamics rates we need to investigate its interannual variability connecting it with variability of major coastal dynamics factors. It is known that in this region one of the main coastal dynamics factors is wave action, which, in turn, depends on wind velocity and direction. Wind data for ice-free period were derived from nearby hydro-meteorological stations. The research was conducted for two sections of the Ob Estuary coast. One section is located on the eastern coast of the estuary (Taz peninsula); the other is located on the western one (Yamal peninsula). Each of these sections is 10 km length. For key-sites of the coast wave-dangerous rhumbs were determined. For ice-free period of each year accumulated summer storm duration (ASSD) - number of hours with strong winds (≥10 m/s) from wave-dangerous directions - was calculated for both sections of coast. Supposing that coast retreat rate is proportional to number of hours with strong winds from wave-dangerous rhumbs, we can approximately assess interannual variability of coast retreat rate. Our research revealed that: 1)There are significant (from hours to a few hundreds of hours) differences in ASSD from year to year due to short ice-free period and high variability of wind velocity and direction. So, we can expect sharp interannual differences in coastal retreat rate. 2)The duration of strong winds from wave-dangerous rhumbs during ice-free period is more on the eastern coast of the estuary than on the western. This goes from the predominance of northern and northwestern winds during ice-free period. These winds cause waves leading to coastal erosion on the eastern coast of estuary and don't cause such waves on the western one. However, we can't draw conclusions about the comparative rates of coastal

  19. Intraseasonal atmospheric variability and its interannual modulation in Central Africa

    NASA Astrophysics Data System (ADS)

    Sandjon, Alain Tchakoutio; Nzeukou, Armand; Tchawoua, Clément

    2012-08-01

    The spatial and temporal structures of the intraseasonal atmospheric variability over central Africa is investigated using 2.5° × 2.5° daily outgoing longwave radiation (OLR) and National Centers for Environmental Prediction (NCEP) Reanalysis zonal winds for the period 1980-2010. The study begins with an overview of the Central African rainfall regime, noting in particular the contrast amongst Western and Eastern parts, with different topography and surface conditions features. The annual mean rainfall and OLR over the region revealed a zone of intense convective activity centered on the equator near 30°E, which extends southward and covers almost all the Congo forest. The annual cycle of rainfall reflects the classical bi-annual shift of Inter-Tropical Convergence Zone across the equatorial belt, between 10°S and 10°N. The result of the empirical orthogonal functions (EOFs) analysis has shown that the three leading EOF modes explain about 45 % of total intraseasonal variability. The power spectra of all the three corresponding principal components (PCs) peak around 45-50 days, indicating a Madden-Julian Oscillation (MJO) signal. The first mode exhibits high positive loadings over Northern Congo, the second over Southern Ethiopia and the third over Southwestern Tanzania. The PCs time series revealed less interannual modulation of intraseasonal oscillations for the Congo mode, while Ethiopian and Tanzanian modes exhibit strong interannual variations. Hövmoller plots of OLR, 200 and 850 hPa NCEP zonal winds found the eastward propagating features to be the dominant pattern in all the three times series, but this propagation is less pronounced in the OLR than in the 850 and 200 hpa zonal wind anomalies. An index of MJO strength was built by averaging the 30-50 day power for each day. A plot of MJO indices and El Niño Southern Oscillation (ENSO) cycle confirm a strong interannual modulation of MJO over Eastern central Africa partially linked with the ENSO

  20. Seasonal and Interannual Variabilities in Tropical Tropospheric Ozone

    NASA Technical Reports Server (NTRS)

    Ziemke, J. R.; Chandra, S.

    1999-01-01

    This paper presents a detailed characterization of seasonal and interannual variability in tropical tropospheric column ozone (TCO). TCO time series are derived from 20 years (1979-1998) of total ozone mapping spectrometer (TOMS) data using the convective cloud differential (CCD) method. Our study identifies three regions in the tropics with distinctly different zonal characteristics related to seasonal and interannual variability. These three regions are the eastern Pacific, Atlantic, and western Pacific. Results show that in both the eastern and western Pacific seasonal-cycle variability of northern hemisphere (NH) TCO exhibits maximum amount during NH spring whereas largest amount in southern hemisphere (SH) TCO occurs during SH spring. In the Atlantic, maximum TCO in both hemispheres occurs in SH spring. These seasonal cycles are shown to be comparable to seasonal cycles present in ground-based ozonesonde measurements. Interannual variability in the Atlantic region indicates a quasi-biennial oscillation (QBO) signal that is out of phase with the QBO present in stratospheric column ozone (SCO). This is consistent with high pollution and high concentrations of mid-to-upper tropospheric O3-producing precursors in this region. The out of phase relation suggests a UV modulation of tropospheric photochemistry caused by the QBO in stratospheric O3. During El Nino events there is anomalously low TCO in the eastern Pacific and high values in the western Pacific, indicating the effects of convectively-driven transport of low-value boundary layer O3 (reducing TCO) and O3 precursors including H2O and OH. A simplified technique is proposed to derive high-resolution maps of TCO in the tropics even in the absence of tropopause-level clouds. This promising approach requires only total ozone gridded measurements and utilizes the small variability observed in TCO near the dateline. This technique has an advantage compared to the CCD method because the latter requires high

  1. A modeling study of processes controlling the Bay of Bengal sea surface salinity interannual variability

    NASA Astrophysics Data System (ADS)

    Akhil, V. P.; Lengaigne, M.; Vialard, J.; Durand, F.; Keerthi, M. G.; Chaitanya, A. V. S.; Papa, F.; Gopalakrishna, V. V.; de Boyer Montégut, Clément

    2016-12-01

    Recent observational studies provided preliminary insights on the interannual variability of Bay of Bengal (BoB) Sea Surface Salinity (SSS), but are limited by the poor data coverage. Here, we describe the BoB interannual SSS variability and its driving processes from a regional eddy-permitting ocean general circulation model forced by interannually varying air-sea fluxes and altimeter-derived discharges of major rivers over the past two decades. Simulated interannual SSS variations compare favorably with both in situ and satellite data and are largest in boreal fall in three regions: the northern BoB, the coastal region off east India, and the Andaman Sea. In the northern BoB, these variations are independent from those in other regions and mostly driven by summer-fall Ganga-Brahmaputra runoff interannual variations. In fall, remote forcing from the Indian Ocean Dipole results in anticlockwise anomalous horizontal currents that drive interannual SSS variations of opposite polarity along the east coast of India and in the Southern Andaman Sea. From winter onward, these anomalies are damped by vertical mixing in the northern BoB and along the east coast of India and by horizontal advection in the Southern Andaman Sea. While river runoff fluctuations locally play a strong role near the Ganga-Brahmaputra river mouth, wind-driven interannual current anomalies are responsible for a large fraction of SSS interannual variability in most of the basin.

  2. 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...

  3. High interannual variability of sea ice thickness in the Arctic region.

    PubMed

    Laxon, Seymour; Peacock, Neil; Smith, Doug

    2003-10-30

    Possible future changes in Arctic sea ice cover and thickness, and consequent changes in the ice-albedo feedback, represent one of the largest uncertainties in the prediction of future temperature rise. Knowledge of the natural variability of sea ice thickness is therefore critical for its representation in global climate models. Numerical simulations suggest that Arctic ice thickness varies primarily on decadal timescales owing to changes in wind and ocean stresses on the ice, but observations have been unable to provide a synoptic view of sea ice thickness, which is required to validate the model results. Here we use an eight-year time-series of Arctic ice thickness, derived from satellite altimeter measurements of ice freeboard, to determine the mean thickness field and its variability from 65 degrees N to 81.5 degrees N. Our data reveal a high-frequency interannual variability in mean Arctic ice thickness that is dominated by changes in the amount of summer melt, rather than by changes in circulation. Our results suggest that a continued increase in melt season length would lead to further thinning of Arctic sea ice.

  4. Interannual Variability and Trends of Extratropical Ozone, Part II: Southern Hemisphere. Part 2; Southern Hemisphere

    NASA Technical Reports Server (NTRS)

    Yung, Y. L.

    2008-01-01

    A principal component analysis (PCA) is applied to the Southern Hemisphere (SH) total column ozone following the method established for analyzing the data in the Northern Hemisphere (NH) in a companion paper. The interannual variability (IAV) of extratropical O-3 in the SH is characterized by four main modes, which account for 75% of the total variance. The first two leading modes are approximately zonally symmetric and relate to the Southern Hemisphere annular mode and the quasi-biennial oscillation. The third and fourth modes exhibit wavenumber-1 structures. Contrary to the Northern Hemisphere, the third and fourth are nor related to stationary waves. Similar results obtained for the 30 100-hPa geopotential thickness.The decreasing O3 trend in the SH is captured in the first mode. The largest trend is at the South Pole, with value similar to-2 Dobson Units (DU)/yr. Both the spatial pattern and trends in the column ozone are captured by the Goddard Earth Observation System chemistry-climate model (GEOS-CCM) in the SH.

  5. 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.

  6. Interannual variation of the surface temperature of tropical forests from satellite observations

    DOE PAGES

    Gao, Huilin; Zhang, Shuai; Fu, Rong; ...

    2016-01-01

    Land surface temperatures (LSTs) within tropical forests contribute to climate variations. However, observational data are very limited in such regions. This study used passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS), providing observations under all weather conditions, to investigate the LST over the Amazon and Congo rainforests. The SSM/I and SSMIS data were collected from 1996 to 2012. The morning and afternoon observations from passive microwave remote sensing facilitate the investigation of the interannual changes of LST anomalies on a diurnal basis. As a result of the variability ofmore » cloud cover and the corresponding reduction of solar radiation, the afternoon LST anomalies tend to vary more than the morning LST anomalies. The dominant spatial and temporal patterns for interseasonal variations of the LST anomalies over the tropical rainforest were analyzed. The impacts of droughts and El Niños on this LST were also investigated. Lastly, the differences between early morning and late afternoon LST anomalies were identified by the remote sensing product, with the morning LST anomalies controlled by humidity (according to comparisons with the National Centers for Environmental Prediction (NCEP) reanalysis data).« less

  7. Interannual variation of the surface temperature of tropical forests from satellite observations

    SciTech Connect

    Gao, Huilin; Zhang, Shuai; Fu, Rong; Li, Wenhong; Dickinson, Robert E.

    2016-01-01

    Land surface temperatures (LSTs) within tropical forests contribute to climate variations. However, observational data are very limited in such regions. This study used passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS), providing observations under all weather conditions, to investigate the LST over the Amazon and Congo rainforests. The SSM/I and SSMIS data were collected from 1996 to 2012. The morning and afternoon observations from passive microwave remote sensing facilitate the investigation of the interannual changes of LST anomalies on a diurnal basis. As a result of the variability of cloud cover and the corresponding reduction of solar radiation, the afternoon LST anomalies tend to vary more than the morning LST anomalies. The dominant spatial and temporal patterns for interseasonal variations of the LST anomalies over the tropical rainforest were analyzed. The impacts of droughts and El Niños on this LST were also investigated. Lastly, the differences between early morning and late afternoon LST anomalies were identified by the remote sensing product, with the morning LST anomalies controlled by humidity (according to comparisons with the National Centers for Environmental Prediction (NCEP) reanalysis data).

  8. Interannual variability of the Upper Paraguay River dynamics over the last 50 years

    NASA Astrophysics Data System (ADS)

    Botta, A.; Girard, P.

    2002-12-01

    The Pantanal, the largest inland wetland on Earth, has a unique aquatic and bird diversity. The existence and functioning of these communities strongly depend on the flood regime of the Upper Paraguay River. Understanding the interannual variability of the river dynamics is therefore essential to the preservation of this wildlife. We analyze 50-year long time series (1935-1995) of annual river height of the Paraguay River at Ladario, and annual mean precipitation over the associated drainage area (313,814 km2). A spectral analysis of the two records shows similar modes of variability (around 2-4, 7 and 15 years). These modes have been previously observed in other hydrographs of the larger Parana River basin. The short-term mode is associated with ENSO, while the two others are linked to SST anomalies over the northern tropical Atlantic. However, the river time series presents a significant increase after 1975 that has no equivalent in the precipitation record. Between 1960 and 1980 the land-use density of the states of Mato Grosso and Mato Grosso do Sul, Brazil has drastically increased (by a factor of 2.1). Such land cover change tends to increase annual river discharge, as well as to affect sedimentation dynamics, eroding the river channel upstream and increasing deposition downstream. Our study will test these different hypotheses and conclude on the respective sensitivity of the river flow to climate variability and anthropogenic disturbance such as land-use extension.

  9. Dipole Structure of Interannual Variations in Summertime Tropical Cyclone Activity over East Asia.

    NASA Astrophysics Data System (ADS)

    Kim, Joo-Hong; Ho, Chang-Hoi; Sui, Chung-Hsiung; Park, Seon Ki

    2005-12-01

    The present study examines variations in summertime (July September) tropical cyclone (TC) activity over East Asia during the period 1951 2003. To represent TC activity, a total of 853 TC best tracks for the period were converted to TC passage frequencies (TPFs) within 5° × 5° latitude longitude grids; TPFs are defined as the percentage values obtained by dividing the number of TC appearances in each grid box by the total number of TCs each year. Empirical orthogonal function analysis of the TPF showed three leading modes: two tropical modes that represent the long-term trend and the relationship with ENSO and one midlatitude mode that oscillates between south of Korea and southeast of Japan with an interannual time scale. The latter proved to be the most remarkable climatic fluctuation of summertime TC activity in the midlatitudes and is referred to as the East Asian dipole pattern (EADP) in this paper.Anomalous atmospheric flows directly connected to the EADP are an enhanced anticyclonic (cyclonic) circulation centering around Japan when the TPF is high south of Korea (southeast of Japan), thereby showing an equivalent barotropic structure in the entire troposphere. This regional circulation anomaly varies in conjunction with the zonally oriented quasi-stationary Rossby wave train in the upper troposphere. This wave train is meridionally trapped in the vicinity of the summer-mean jet stream; therefore, the mean jet stream alters its internal meandering structure according to the phase of the wave train.

  10. Interannual variability of the regional CO2 and CH4 fluxes estimated with GOSAT observations

    NASA Astrophysics Data System (ADS)

    Maksyutov, Shamil; Takagi, Hiroshi; Kim, Heon-Sook; Saito, Makoto; Mabuchi, Kazuo; Matsunaga, Tsuneo; Ito, Akihiko; Belikov, Dmitry; Oda, Tomohiro; Valsala, Vinu; Morino, Isamu; Yoshida, Yukio; Yokota, Tatsuya

    2014-05-01

    GOSAT Level 4 products - monthly regional surface flux estimates by inverse modeling from CO2 and CH4 GOSAT column-averaged mixing ratios and ground-based observational data using a global atmospheric transport model - have been updated recently to cover the 2-year period starting June 2009. This temporal extension provides look at the interannual flux variability including events of CO2 and CH4 emissions from a large-scale climate anomaly and resultant forest fires in Russia in 2010. Higher emissions of CO2 and CH4 in western Russia in the summer of 2010 are estimated when GOSAT observations are also included in the inverse modeling compared to just using ground-based data. The estimated summer emissions in 2010 are also higher than in the same season of the adjacent years. GOSAT compliments the ground-based networks by observing the concentration response to emissions closer to fire locations, resulting in the inverse models identifying emission regions more accurately. Elsewhere, GOSAT-aided flux estimates point to higher CH4 emissions (compared to ground-based only estimates) in the remote sub-tropical regions of the South America, Africa and South-East Asia. Higher emissions over South America can be attributed to biomass burning and anthropogenic sources, while in South-East Asia those are likely to be caused by agriculture and natural ecosystems.

  11. Hydroclimate of the Western United States Based on Observations and Regional Climate Simulations of 1981-2000. Part II: Mesoscale ENSO Anomalies

    SciTech Connect

    Leung, Lai R.; Qian, Yun; Bian, Xindi; Hunt, Allen G.

    2003-06-15

    Regional climate of the western U.S. shows clear footprints of interactions between atmospheric circulation and orography. The unique features of the diverse climate regimes challenge climate modeling. These papers provide detailed analyses of observations and regional climate simulations to improve our understanding and modeling of regional climate of the region. Part II focuses on evaluation of simulated interannual climate variability associated with the El Nino-Southern Oscillation.

  12. Laparoscopic repair of recurrent hernias.

    PubMed

    Felix, E L; Michas, C A; McKnight, R L

    1995-02-01

    The purpose of this study was to evaluate the results of a laparoscopic approach to recurrent inguinal hernia repair which dissected the entire inguinal floor and repaired all potential areas of recurrence without producing tension. Both a transabdominal preperitoneal and a totally extraperitoneal laparoscopic approach were utilized. Ninety recurrent hernias were repaired in 81 patients. The patients had 26 indirect, 36 direct, and 26 pantaloon recurrent hernias of which eight had a femoral component. In all but one patient the primary operations were open anterior repairs. The median follow-up was 14 months, ranging from 1 to 28 months. Patients returned to normal activities in an average of 1 week. The only recurrence observed was in the one patient whose primary repair was laparoscopic. When the entire inguinal floor of the recurrent hernia was redissected and buttressed with mesh, early recurrence was eliminated and recovery was shortened.

  13. Interannual variation, decadal trend, and future change in ozone outflow from East Asia

    NASA Astrophysics Data System (ADS)

    Zhu, Jia; Liao, Hong; Mao, Yuhao; Yang, Yang; Jiang, Hui

    2017-03-01

    We examine the past and future changes in the O3 outflow from East Asia using a global 3-D chemical transport model, GEOS-Chem. The simulations of Asian O3 outflow for 1986-2006 are driven by the assimilated GEOS-4 meteorological fields, and those for 2000-2050 are driven by the meteorological fields archived by the NASA Goddard Institute for Space Studies (GISS) general circulation model (GCM) 3 under the IPCC SRES A1B scenario. The evaluation of the model results against measurements shows that the GEOS-Chem model captures the seasonal cycles and interannual variations of tropospheric O3 concentrations fairly well with high correlation coefficients of 0.82-0.93 at four ground-based sites and 0.55-0.88 at two ozonesonde sites where observations are available. The increasing trends in surface-layer O3 concentrations in East Asia over the past 2 decades are captured by the model, although the modeled O3 trends have low biases. Sensitivity studies are conducted to examine the respective impacts of meteorological parameters and emissions on the variations in the outflow flux of O3. When both meteorological parameters and anthropogenic emissions varied from 1986-2006, the simulated Asian O3 outflow fluxes exhibited a statistically insignificant decadal trend; however, they showed large interannual variations (IAVs) with seasonal values of 4-9 % for the absolute percent departure from the mean (APDM) and an annual APDM value of 3.3 %. The sensitivity simulations indicated that the large IAVs in O3 outflow fluxes were mainly caused by variations in the meteorological conditions. The variations in meteorological parameters drove the IAVs in O3 outflow fluxes by altering the O3 concentrations over East Asia and by altering the zonal winds; the latter was identified to be the key factor, since the O3 outflow was highly correlated with zonal winds from 1986-2006. The simulations of the 2000-2050 changes show that the annual outflow flux of O3 will increase by 2.0, 7.9, and

  14. Interannual variability of monthly Southern Ocean sea ice distributions

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.

    1992-01-01

    The interannual variability of the Southern-Ocean sea-ice distributions was mapped and analyzed using data from Nimbus-5 ESMR and Nimbus-7 SMMR, collected from 1973 to 1987. The set of 12 monthly maps obtained reveals many details on spatial variability that are unobtainable from time series of ice extents. These maps can be used as baseline maps for comparisons against future Southern Ocean sea ice distributions. The maps are supplemented by more detailed maps of the frequency of ice coverage, presented in this paper for one month within each of the four seasons, and by the breakdown of these results to the periods covered individually by each of the two passive-microwave imagers.

  15. Mean surface water balance over Africa and its interannual variability

    SciTech Connect

    Nicholson, S.E.; Kim, J.; Ba, M.B.; Lare, A.R.

    1997-12-01

    This article presents calculations of surface water balance for the African continent using a revised version of the Lettau climatonomy. Calculations are based on approximately 1400 rainfall stations, with records generally covering 60 yr or longer. Continental maps of evapotranspiration. runoff, and soil moisture are derived for January, July, and the annual mean. The model is also used to provide a gross estimate of the interannual variability of these parameters over most of the continent and local water balance calculations for a variety of locations in Africa. The results are compared with four other comprehensive global water balance studies. The results of this study are being used to produce a gridded dataset for the continent, with potential applications for numerical modeling studies. 50 refs., 18 figs., 3 tabs.

  16. SCIAMACHY CO over the oceans: 2003-2007 interannual variability

    NASA Astrophysics Data System (ADS)

    Gloudemans, A. M. S.; de Laat, A. T. J.; Schrijver, H.; Aben, I.; Meirink, J. F.; van der Werf, G. R.

    2009-03-01

    We present a new method to obtain accurate SCIAMACHY CO columns over clouded ocean scenes. Based on an improved version of the Iterative Maximum Likelihood Method (IMLM) retrieval algorithm, we now have retrieved five years of data over both land and clouded ocean scenes between 2003 and 2007. The ocean-cloud method uses the CH4 columns retrieved simultaneously with the CO columns to determine the cloud top height. The CH4 cloud top height is in good agreement with the FRESCO+ cloud top height determined from UV-VIS oxygen-A band measurements, providing confidence that the CH4 cloud top height is a good diagnostic of the cloud top height over (partially) clouded ocean scenes. The CO measurements over clouded ocean scenes have been compared with collocated modeled CO columns over the same clouds and agree well. Using clouded ocean scenes quadruples the number of useful CO measurements compared to land-only measurements. The five-year CO data set over land and clouded ocean scenes presented here is based on an improved version of the IMLM algorithm which includes a more accurate determination of the random instrument-noise error for CO. This leads to a smaller spread in the differences between single CO measurements and the corresponding model values. The new version, IMLM version 7.4, also uses updated spectroscopic parameters for H2O and CH4 but this has only a minor impact on the retrieved CO columns. The five-year data set shows significant interannual variability over land and over clouded ocean scenes. Three examples are highlighted: the Asian outflow of pollution over the northern Pacific, the biomass-burning outflow over the Indian Ocean originating from Indonesia, and biomass burning in Brazil. In general there is good agreement between observed and modeled seasonal cycles and interannual variability.

  17. Seasonal and interannual temperature variations in the tropical stratosphere

    SciTech Connect

    Reid, G.C.

    1994-09-20

    Temperature variations in the tropical lower and middle stratosphere are influenced by at least five distinct driving forces. These are (1) the mechanism of the regular seasonal cycle, (2) the quasi-biennial oscillation (QBO) in zonal winds, (3) the semiannual zonal wind oscillation (SAO) at higher levels, (4) El Nino-Southern Oscillation (ENSO) effects driven by the underlying troposphere, and (5) radiative effects, including volcanic aerosol heating. Radiosonde measurements of temperatures from a number of tropical stations, mostly in the western Pacific region, are used in this paper to examine the characteristic annual and interannual temperature variability in the stratosphere below the 10-hPa pressure level ({approximately} 31 km) over a time period of 17 years, chosen to eliminate or at least minimize the effect of volcanic eruptions. Both annual and interannual variations are found to show a fairly distinct transition between the lower and the middle stratosphere at about the 35-hPa level ({approximately} 23 km). The lower stratosphere, below this transition level, is strongly influenced by the ENSO cycle as well as by the QBO. The overall result of the interaction is to modulate the amplitude of the normal stratospheric seasonal cycle and to impose a biennial component on it, so that alternate seasonal cycles are stronger or weaker than normal. Additional modulation by the ENSO cycle occurs at its quasi-period of 3-5 years, giving rise to a complex net behavior. In the middle stratosphere above the transition level, there is no discernible ENSO influence, and departures from the regular semiannual seasonal cycle are dominated by the QBO. Recent ideas on the underlying physical mechanisms governing these variations are discussed, as is the relationship of the radiosonde measurements to recent satellite remote-sensing observations. 37 refs., 8 figs., 1 tab.

  18. Interannual Variation in Stand Transpiration is Dependent Upon Tree Species

    NASA Astrophysics Data System (ADS)

    Ewers, B. E.; Mackay, D. S.; Burrows, S. N.; Ahl, D. E.; Samanta, S.

    2003-12-01

    In order to successfully predict transpirational water fluxes from forested watersheds, interannual variability in transpiration must be quantified and understood. In a heterogeneous forested landscape in northern Wisconsin, we quantified stand transpiration across four forest cover types representing more than 80 percent of the land area in order to 1) quantify differences in stand transpiration and leaf area over two years and 2) determine the mechanisms governing the changes in transpiration over two years. We measured sap flux in eight trees of each tree species in the four cover types. We found that in northern hardwoods, the leaf area of sugar maple increased between the two measurement years with transpiration per unit ground area increasing even more than could be explained by leaf area. In an aspen stand, tent caterpillars completely defoliated the stand for approximately a month until a new set of leaves flushed out. The new set of leaves resulted in a lower leaf area but the same transpiration per unit leaf area indicating there was no physiological compensation for the lower leaf area. At the same time, balsam fir growing underneath the aspen increased their transpiration rate in response to greater light penetration through the dominant aspen canopy Red pine had a thirty percent change in leaf area within a growing season due to multiple cohorts of leaves and transpiration followed this leaf area dynamic. In a forested wetland, white cedar transpiration was proportional to surface water depth between the two years. Despite the specific tree species' effects on stand transpiration, all species displayed a minimum water potential regulation resulting in a saturating response of transpiration to vapor pressure deficit that did not vary across the two years. This physiological set point will allow future water flux models to explain mechanistically interannual variability in transpiration of this and similar forests.

  19. Interannual Variability of the Tropical Energy Balance: Reconciling Observations and Models

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Fitzjarrald, D. E.; Goodman, H. Michael (Technical Monitor)

    2000-01-01

    Since the beginning of the World Climate Research Program's Global Precipitation Climatology Project (GPCP) satellite remote sensing of precipitation has made dramatic improvements, particularly for tropical regions. Data from microwave and infrared sensors now form the most critical input to precipitation data sets and can be calibrated with surface gauges to so that the strengths of each data source can be maximized in some statistically optimal sense. Recent availability of the TRMM (Tropical Rainfall Measuring Mission) has further aided in narrowing uncertainties in rainfall over the tropics and subtropics. Although climate modeling efforts have long relied on space-based precipitation estimates for validation, we now are in a position to make more quantitative assessments of model performance, particularly in tropical regions. An integration of the CCM3 using observed SSTs as a lower boundary condition is used to examine how well this model responds to ENSO forcing in terms of anomalous precipitation. An integration of the NCEP spectral model used for the Reanalysis-11 effort is also examined. This integration is run with specified SSTs, but no data assimilation. Our analysis focuses on two aspects. First are the spatial anomalies that are indicative of dislocations in Hadley and Walker circulations. Second, we consider the ability of models to replicate observed increases in oceanic precipitation that are noted in satellite observations for large ENSO events. Finally, we consider a slab ocean version of the CCM3 model with prescribed ocean heat transports that mimic upwelling anomalies, but which still allows the surface energy balance to be predicted. This less restrictive experiment is used to understand why model experiments with specified SSTs seem to have noticeably less interannual variability than do the satellite precipitation observations.

  20. Interannual variability of the atmospheric CO2 growth rate: relative contribution from precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zeng, N.; Wang, M. R.

    2015-12-01

    The interannual variability (IAV) in atmospheric CO2 growth rate (CGR) is closely connected with the El Niño-Southern Oscillation. However, sensitivities of CGR to temperature and precipitation remain largely uncertain. This paper analyzed the relationship between Mauna Loa CGR and tropical land climatic elements. We find that Mauna Loa CGR lags precipitation by 4 months with a correlation coefficient of -0.63, leads temperature by 1 month (0.77), and correlates with soil moisture (-0.65) with zero lag. Additionally, precipitation and temperature are highly correlated (-0.66), with precipitation leading by 4-5 months. Regression analysis shows that sensitivities of Mauna Loa CGR to temperature and precipitation are 2.92 ± 0.20 Pg C yr-1 K-1 and -0.46 ± 0.07 Pg C yr-1 100 mm-1, respectively. Unlike some recent suggestions, these empirical relationships favor neither temperature nor precipitation as the dominant factor of CGR IAV. We further analyzed seven terrestrial carbon cycle models, from the TRENDY project, to study the processes underlying CGR IAV. All models capture well the IAV of tropical land-atmosphere carbon flux (CFTA). Sensitivities of the ensemble mean CFTA to temperature and precipitation are 3.18 ± 0.11 Pg C yr-1 K-1 and -0.67 ± 0.04 Pg C yr-1 100 mm-1, close to Mauna Loa CGR. Importantly, the models consistently show the variability in net primary productivity (NPP) dominates CGR, rather than soil respiration. Because NPP is largely driven by precipitation, this suggests a key role of precipitation in CGR IAV despite the higher CGR correlation with temperature. Understanding the relative contribution of CO2 sensitivity to precipitation and temperature has important implications for future carbon-climate feedback using such "emergent constraint".

  1. Interannual variability of the atmospheric CO2 growth rate: roles of precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Zeng, Ning; Wang, Meirong

    2016-04-01

    The interannual variability (IAV) in atmospheric CO2 growth rate (CGR) is closely connected with the El Niño-Southern Oscillation. However, sensitivities of CGR to temperature and precipitation remain largely uncertain. This paper analyzed the relationship between Mauna Loa CGR and tropical land climatic elements. We find that Mauna Loa CGR lags precipitation by 4 months with a correlation coefficient of -0.63, leads temperature by 1 month (0.77), and correlates with soil moisture (-0.65) with zero lag. Additionally, precipitation and temperature are highly correlated (-0.66), with precipitation leading by 4-5 months. Regression analysis shows that sensitivities of Mauna Loa CGR to temperature and precipitation are 2.92 ± 0.20 PgC yr-1 K-1 and -0.46 ± 0.07 PgC yr-1 100 mm-1, respectively. Unlike some recent suggestions, these empirical relationships favor neither temperature nor precipitation as the dominant factor of CGR IAV. We further analyzed seven terrestrial carbon cycle models, from the TRENDY project, to study the processes underlying CGR IAV. All models capture well the IAV of tropical land-atmosphere carbon flux (CFTA). Sensitivities of the ensemble mean CFTA to temperature and precipitation are 3.18 ± 0.11 PgC yr-1 K-1 and -0.67 ± 0.04 PgC yr-1 100 mm-1, close to Mauna Loa CGR. Importantly, the models consistently show the variability in net primary productivity (NPP) dominates CGR, rather than heterotrophic respiration. Because previous studies have proved that NPP is largely driven by precipitation in tropics, it suggests a key role of precipitation in CGR IAV despite the higher CGR correlation with temperature. Understanding the relative contribution of CO2 sensitivity to precipitation and temperature has important implications for future carbon-climate feedback using such ''emergent constraint''.

  2. Species differences in evergreen tree transpiration at daily, seasonal, and interannual timescales

    NASA Astrophysics Data System (ADS)

    Link, P.; Simonin, K. A.; Oshun, J.; Dietrich, W.; Dawson, T. E.; Fung, I.

    2012-12-01

    Mediterranean climates have rainy winter and dry summer seasons, so the season of water availability (winter) is out of phase with the season of light availability and atmospheric demand (summer). In this study, we investigate the seasonality of tree transpiration in a Mediterranean climate, using observations from a small (8000 m2), forested, steep (~35 degree) hillslope at the UC Angelo Reserve, in the northern California Coast Range. The site is instrumented with over 850 sensors transmitting hydrologic and meteorological data at less than 30-minute intervals. Here, we analyze four years of high-frequency measurements from 45 sap flow sensors in 30 trees, six depth profiles of soil moisture measured by TDR, and spatially distributed measurements of air temperature, relative humidity, solar radiation, and other meteorological variables. The sap flow measurements show a difference in transpiration seasonality between common California Coast Range evergreen tree species. Douglas firs (Pseudotsuga menziesii) maintain significant transpiration through the winter rainy season and transpire maximally in the spring, but Douglas fir transpiration declines sharply in the summer dry season. Madrones (Arbutus menziesii), in contrast, transpire maximally in the summer dry season. The seasonal patterns are quantified using principal component analysis. Nonlinear regressions against environmental variables show that the difference in transpiration seasonality arises from different sensitivities to atmospheric demand (VPD) and root-zone moisture. The different sensitivities to VPD and root-zone moisture cause species differences not just in seasonal patterns, but also in high temporal frequency (daily to weekly) variability of transpiration. We also contrast the interannual variability of dry season transpiration among the different species, and show that precipitation above a threshold triggers a Douglas fir response. Finally, we use a simple 1-D model of the atmospheric

  3. Topographic position modulates the mycorrhizal response of oak trees to interannual rainfall variability.

    PubMed

    Querejeta, José I; Egerton-Warburton, Louise M; Allen, Michael F

    2009-03-01

    California coast live oak (Quercus agrifolia) forms tripartite symbiotic associations with arbuscular (AMF) and ectomycorrhizal (EMF) fungi. We selected oak individuals differing in topographic position and depth to groundwater (mesic valley vs. xeric hill sites) to investigate changes of tree mycorrhizal status in response to interannual rainfall variability. EMF root colonization, as well as hyphal abundance and viability in upper rhizosphere soil (0-30 cm), were negatively affected by severe multi-year drought, although not to the same extent in each topographic location. Oak trees growing in hill sites showed EMF colonization levels <1% in upper roots during drought. By contrast, oaks in valley sites maintained much higher EMF colonization (>19%) in upper roots during drought. EMF root colonization increased sharply at both topographic positions during the ensuing wet year (78% in valley, 49% in hill), which indicates that the mycorrhizal status of roots in upper rhizosphere soil is highly responsive to interannual rainfall variability. Across sites and years, percentage EMF colonization and soil hyphal density and viability were strongly positively correlated with soil moisture potential, but percentage AMF root colonization was not. Interestingly, changes in percentage EMF root colonization and density of viable hyphae between a wet and a dry year were proportionally much greater in xeric hill sites than in mesic valley sites. The mycorrhizal status of oak trees was particularly responsive to changes in soil moisture at the hill sites, where roots in upper rhizosphere soil shifted from almost exclusively AMF during severe drought to predominantly EMF during the ensuing wet year. By contrast, the mycorrhizal status of oaks in the valley sites was less strongly coupled to current meteorological conditions, as roots in upper soil layers remained predominantly EMF during both a dry and a wet year. Canopy shading and hydraulic lift by oaks in valley sites likely

  4. East Asian Monsoon controls on the inter-annual variability in precipitation isotope ratio in Japan

    NASA Astrophysics Data System (ADS)

    Kurita, N.; Fujiyoshi, Y.; Nakayama, T.; Matsumi, Y.; Kitagawa, H.

    2015-02-01

    To elucidate the mechanism for how the East Asian Monsoon (EAM) variability have influenced the isotope proxy records in Japan, we explore the primary driver of variations of precipitation isotopes at multiple temporal scales (event, seasonal and inter-annual scales). Using a new 1-year record of the isotopic composition of event-based precipitation and continuous near-surface water vapor at Nagoya in central Japan, we identify the key atmospheric processes controlling the storm-to-storm isotopic variations through an analysis of air mass sources and rainout history during the transport of moisture to the site, and then apply the identified processes to explain the inter-annual isotopic variability related to the EAM variability in the historical 17-year long Tokyo station record in the Global Network of Isotopes in Precipitation (GNIP). In the summer, southerly flows transport moisture with higher isotopic values from subtropical marine regions and bring warm rainfall enriched with heavy isotopes. The weak monsoon summer corresponds to enriched isotopic values in precipitation, reflecting higher contribution of warm rainfall to the total summer precipitation. In the strong monsoon summer, the sustaining Baiu rainband along the southern coast of Japan prevents moisture transport across Japan, so that the contribution of warm rainfall is reduced. In the winter, storm tracks are the dominant driver of storm-to-storm isotopic variation and relatively low isotopic values occur when a cold frontal rainband associated with extratropical cyclones passes off to the south of the Japan coast. The weak monsoon winter is characterized by lower isotopes in precipitation, due to the distribution of the cyclone tracks away from the southern coast of Japan. In contrast, the northward shift of the cyclone tracks and stronger development of cyclones during the strong monsoon winters decrease the contribution of cold frontal precipitation, resulting in higher isotopic values in

  5. Seasonality of oceanic primary production and its interannual variability from 1998 to 2007

    NASA Astrophysics Data System (ADS)

    Brown, Christopher W.; Schollaert Uz, Stephanie; Corliss, Bruce H.

    2014-08-01

    The seasonality of primary productivity plays an important role in nutrient and carbon cycling. We quantify the seasonality of satellite-derived, oceanic net primary production (NPP) and its interannual variability during the first decade of the SeaWiFS mission (1998 to 2007) using a normalized seasonality index (NSI). The NSI, which is based upon production half-time, t(1/2), generally becomes progressively more episodic with increasing latitude in open ocean waters, spanning from a relatively constant rate of primary productivity throughout the year (mean t(1/2) ~5 months) in subtropical waters to more pulsed events (mean t(1/2) ~3 months) in subpolar waters. This relatively gradual, poleward pattern in NSI differs from recent estimates of phytoplankton bloom duration, another measure of seasonality, at lower latitudes (~40°S-40°N). These differences likely reflect the temporal component of production assessed by each metric, with NSI able to more fully capture the irregular nature of production characteristic of waters in this zonal band. The interannual variability in NSI was generally low, with higher variability observed primarily in frontal and seasonal upwelling zones. The influence of the El Niño-Southern Oscillation on this variability was clearly evident, particularly in the equatorial Pacific, where primary productivity was anomalously episodic from the date line east to the coast of South America in 1998. Yearly seasonality and the magnitude of annual production were generally positively correlated at mid-latitudes and negatively correlated at tropical latitudes, particularly in a region bordering the Pacific equatorial divergence. This implies that increases of annual production in the former region are attained over the course of a year by shorter duration but higher magnitude NPP events, while in the latter areas it results from an increased frequency or duration of similar magnitude events. Statistically significant trends in the seasonality

  6. Not all droughts are created equal: The impacts of interannual drought pattern and magnitude on grassland carbon cycling

    USGS Publications Warehouse

    Hoover, David L.; Rogers, Brendan M.

    2016-01-01

    Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle ‘press-droughts’, and shorter term but extreme ‘pulse-droughts’. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems.

  7. Not all droughts are created equal: the impacts of interannual drought pattern and magnitude on grassland carbon cycling.

    PubMed

    Hoover, David L; Rogers, Brendan M

    2016-05-01

    Climate extremes, such as drought, may have immediate and potentially prolonged effects on carbon cycling. Grasslands store approximately one-third of all terrestrial carbon and may become carbon sources during droughts. However, the magnitude and duration of drought-induced disruptions to the carbon cycle, as well as the mechanisms responsible, remain poorly understood. Over the next century, global climate models predict an increase in two types of drought: chronic but subtle 'press-droughts', and shorter term but extreme 'pulse-droughts'. Much of our current understanding of the ecological impacts of drought comes from experimental rainfall manipulations. These studies have been highly valuable, but are often short term and rarely quantify carbon feedbacks. To address this knowledge gap, we used the Community Land Model 4.0 to examine the individual and interactive effects of pulse- and press-droughts on carbon cycling in a mesic grassland of the US Great Plains. A series of modeling experiments were imposed by varying drought magnitude (precipitation amount) and interannual pattern (press- vs. pulse-droughts) to examine the effects on carbon storage and cycling at annual to century timescales. We present three main findings. First, a single-year pulse-drought had immediate and prolonged effects on carbon storage due to differential sensitivities of ecosystem respiration and gross primary production. Second, short-term pulse-droughts caused greater carbon loss than chronic press-droughts when total precipitation reductions over a 20-year period were equivalent. Third, combining pulse- and press-droughts had intermediate effects on carbon loss compared to the independent drought types, except at high drought levels. Overall, these results suggest that interannual drought pattern may be as important for carbon dynamics as drought magnitude and that extreme droughts may have long-lasting carbon feedbacks in grassland ecosystems.

  8. Effect of non-homogeneity in flux footprint on the interpretation of seasonal, annual, and interannual ecosystem carbon exchange

    NASA Astrophysics Data System (ADS)

    Griebel, A.; Bennett, L. T.; Metzen, D.; Cleverly, J. R.; Burba, G. G.; Arndt, S. K.

    2015-12-01

    Carbon flux measurements using the eddy covariance method rely on several assumptions, including reasonably uniform terrain and homogenous vegetation. These are not always possible in complex terrain, structurally variable native vegetation or in disturbed ecosystems. Consequently, an increasing number of flux sites are located over not fully homogeneous areas. This implies that observed year-to-year variations in CO2 budgets may not always be related only to changes in the key driving factors such as weather, canopy state and physiology, but may also be affected by differences in the flux footprints between years. This may bias budget estimates over many locations, since a large number of flux sites are affected by wind channelling, contrasting climatic conditions with wind direction (e.g. maritime sites) and by variations of continental-scale climate patterns that modify prevailing wind directions. We tested the effects of a non-homogeneous footprint on annual carbon estimates for an evergreen forest, where the combination of terrain, weather and anthropogenic management shaped the local forest structure. Interactions among these factors caused the key drivers regulating carbon fluxes (such as LAI, temperature, VPD and turbulence) to vary significantly with wind direction, and their combinations resulted in pronounced carbon sequestration 'hotspots' that impacted instantaneous fluxes. These were most distinctive during the summer months, and they varied in extent and magnitude depending on prevailing weather. Consequently, interannual variations in footprints affected up to 18.9% of seasonal estimates during the summer months, and up to 23.1% of annual carbon budget estimates. The footprint-related bias was largest at 48.7% under 'ideal' uptake conditions (clear sky, mid-day during summer). We further present a procedure to recognise and quantify the apparent interannual variations in carbon estimates attributable to year-to-year variations in flux footprint.

  9. 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.

  10. Multiscale recurrence quantification analysis of order recurrence plots

    NASA Astrophysics Data System (ADS)

    Xu, Mengjia; Shang, Pengjian; Lin, Aijing

    2017-03-01

    In this paper, we propose a new method of multiscale recurrence quantification analysis (MSRQA) to analyze the structure of order recurrence plots. The MSRQA is based on order patterns over a range of time scales. Compared with conventional recurrence quantification analysis (RQA), the MSRQA can show richer and more recognizable information on the local characteristics of diverse systems which successfully describes their recurrence properties. Both synthetic series and stock market indexes exhibit their properties of recurrence at large time scales that quite differ from those at a single time scale. Some systems present more accurate recurrence patterns under large time scales. It demonstrates that the new approach is effective for distinguishing three similar stock market systems and showing some inherent differences.

  11. Recurrent brachial plexus neuropathy.

    PubMed

    Bradley, W G; Madrid, R; Thrush, D C; Campbell, M J

    1975-09-01

    The clinical, electrophysiological and pathological changes in 3 patients with recurrent attacks of non-traumatic brachial plexus neuropathy have been described. Two had recurrent attacks and a dominant family history of similar attacks, together with evidence of lesser degrees of nerve involvement outside the brachial plexus. In one patient the attacks were moderately painful, while in the other there was little or no pain. Only one showed undue slowing of motor nerve conduction during ischaemia, but in both cases the sural nerves had the changes of tomaculous neuropathy, with many sausage-shaped swellings of the myelin sheaths, and extensive segmental demyelination and remyelination. The third patient had two attacks of acute brachial plexus neuropathy which were both extremely painful. The clinical features were compatible with a diagnosis of neuralgic amuotrophy. In the second attack, there was vagus nerve involvement and the sural nerve showed evidence of healed extensive segmental demyelination. The various syndromes presenting with acute non-traumatic brachial plexus neuropathy are reviewed, and a tentative nonsological classification advanced. Most patients fall into the category of acute, painful paralysis with amyotrophy, with no family history and no evidence of lesions outside the brachial plexus. It is suggested that the term "neuralgic amyotrophy" be restricted to this group. Patients with features outside this clinical picture probably suffer from other disease entities presenting with brachial plexus neuropathy. The familial cases constitute one or more aetioliogical subgroups, differing from neuralgic amyotrophy in the frequency of recurrences, the relative freedom from pain in the attacks, the frequency of nerve lesions outside the brachial plexus, and of hypotelorism. Individual attacks of acute brachial plexus neuropathy, however, may be identical in patients with the different diseases, and further pathological and biochemical studies are

  12. The role of C3 and C4 grasses to interannual variability in remotely sensed ecosystem performance over the US Great Plains

    USGS Publications Warehouse

    Ricotta, C.; Reed, Bradley C.; Tieszen, Larry L.

    2003-01-01

    Time integrated normalized difference vegetation index (ΣNDVI) derived from National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) multi-temporal imagery over a 10-year period (1989–1998) was used as a surrogate for primary production to investigate the impact of interannual climate variability on grassland performance for central and northern US Great Plains. First, the contribution of C3 and C4 species abundance to the major grassland ecosystems of the US Great Plains is described. Next, the relation between mean ΣNDVI and the ΣNDVI coefficient of variation (CV ΣNDVI) used as a proxy for interannual climate variability is analysed. Results suggest that the differences in the long-term climatic control over ecosystem performance approximately coincide with changes between C3- and C4-dominant grassland classes. Variation in remotely sensed net primary production over time is higher for the southern and western plains grasslands (primarily C4 grasslands), whereas the C3-dominated classes in the northern and eastern portion of the US Great Plains, generally show lower CV ΣNDVI values.

  13. Recurrent tarsal tunnel syndrome.

    PubMed

    Gould, John S

    2014-09-01

    Recurrence of tarsal tunnel syndrome after surgery may be due to inadequate release, lack of understanding or appreciation of the actual anatomy involved, variations in the anatomy of the nerve(s), failure to execute the release properly, bleeding with subsequent scarring, damage to the nerve and branches, persistent hypersensitivity of the nerves, and preexisting intrinsic damage to the nerve. Approaches include more thorough release, use of barrier materials to decrease adherence of the nerve to surrounding tissues to avoid traction neuritis, excisions of neuromas using conduits, and consideration of nerve stimulators and systemic medications to deal with persistent neural pain.

  14. Recurrent respiratory papillomatosis.

    PubMed

    Venkatesan, Naren N; Pine, Harold S; Underbrink, Michael P

    2012-06-01

    Recurrent respiratory papillomatosis (RRP) is a rare, benign disease with no known cure. RRP is caused by infection of the upper aerodigestive tract with the human papillomavirus (HPV). Passage through the birth canal is thought to be the initial transmission event, but infection may occur in utero. HPV vaccines have helped to provide protection from cervical cancer; however, their role in the prevention of RRP is undetermined. Clinical presentation of initial symptoms of RRP may be subtle. RRP course varies, and current management focuses on surgical debulking of papillomatous lesions with or without concurrent adjuvant therapy.

  15. Recurrent acute pancreatitis.

    PubMed

    Khurana, Vishal; Ganguly, Ishita

    2014-09-28

    Recurrent acute pancreatitis (RAP) is commonly encountered, but less commonly understood clinical entity, especially idiopathic RAP, with propensity to lead to repeated attacks and may be chronic pancreatitis if attacks continue to recur. A great number of studies have been published on acute pancreatitis, but few have focused on RAP. Analysing the results of clinical studies focusing specifically on RAP is problematic in view due to lack of standard definitions, randomised clinical trials, standard evaluation protocol used and less post intervention follow-up duration. With the availability of newer investigation modalities less number of etiologies will remains undiagnosed. This review particularly is focused on the present knowledge in understanding of RAP.

  16. Impacts of fire emissions and transport pathways on the interannual variation of CO in the tropical upper troposphere

    NASA Astrophysics Data System (ADS)

    Huang, L.; Fu, R.; Jiang, J. H.

    2014-04-01

    This study investigates the impacts of fire emission, convection, various climate conditions and transport pathways on the interannual variation of carbon monoxide (CO) in the tropical upper troposphere (UT), by evaluating the field correlation between these fields using multi-satellite observations and principle component analysis, and the transport pathway auto-identification method developed in our previous study. The rotated empirical orthogonal function (REOF) and singular value decomposition (SVD) methods are used to identify the dominant modes of CO interannual variation in the tropical UT and to study the coupled relationship between UT CO and its governing factors. Both REOF and SVD results confirm that Indonesia is the most significant land region that affects the interannual variation of CO in the tropical UT, and El Niño-Southern Oscillation (ENSO) is the dominant climate condition that affects the relationships between surface CO emission, convection and UT CO. In addition, our results also show that the impact of El Niño on the anomalous CO pattern in the tropical UT varies strongly, primarily due to different anomalous emission and convection patterns associated with different El Niño events. In contrast, the anomalous CO pattern in the tropical UT during La Niña period appears to be less variable among different events. Transport pathway analysis suggests that the average CO transported by the "local convection" pathway (ΔCOlocal) accounts for the differences of UT CO between different ENSO phases over the tropical continents during biomass burning season. ΔCOlocal is generally higher over Indonesia-Australia and lower over South America during El Niño years than during La Niña years. The other pathway ("advection within the lower troposphere followed by convective vertical transport") occurs more frequently over the west-central Pacific during El Niño years than during La Niña years, which may account for the UT CO differences over this

  17. The role of drought on wheat yield interannual variability in the Iberian Peninsula from 1929 to 2012

    NASA Astrophysics Data System (ADS)

    Páscoa, P.; Gouveia, C. M.; Russo, A.; Trigo, R. M.

    2016-10-01

    The production of wheat in the Iberian Peninsula is strongly affected by climate conditions being particularly vulnerable to interannual changes in precipitation and long-term trends of both rainfall and evapotranspiration. Recent trends in precipitation and temperature point to an increase in dryness in this territory, thus highlighting the need to understand the dependence of wheat yield on climate conditions. The present work aims at studying the relation between wheat yields and drought events in the Iberian Peninsula, using a multiscalar drought index, the standardized precipitation evapotranspiration index (SPEI), at various timescales. The effects of the occurrence of dry episodes on wheat yields were analyzed, on regional spatial scale for two subperiods (1929-1985 and 1986-2012). The results show that in western areas, wheat yield is positively affected by dryer conditions, whereas the opposite happens in eastern areas. The winter months have a bigger influence in the west while the east is more dependent on the spring and summer months. Moreover, in the period of 1986-2012, the simultaneous occurrence of low-yield anomalies and dry events reaches values close to 100 % over many provinces. Results suggest that May and June have a strong control on wheat yield, namely, for longer timescales (9 to 12 months). A shift in the dependence of wheat yields on climatic droughts is evidenced by the increase in the area with positive correlation and the decrease in area with negative correlation between wheat yields and SPEI, probably due to the increase of dry events.

  18. The role of drought on wheat yield interannual variability in the Iberian Peninsula from 1929 to 2012

    NASA Astrophysics Data System (ADS)

    Páscoa, P.; Gouveia, C. M.; Russo, A.; Trigo, R. M.

    2017-03-01

    The production of wheat in the Iberian Peninsula is strongly affected by climate conditions being particularly vulnerable to interannual changes in precipitation and long-term trends of both rainfall and evapotranspiration. Recent trends in precipitation and temperature point to an increase in dryness in this territory, thus highlighting the need to understand the dependence of wheat yield on climate conditions. The present work aims at studying the relation between wheat yields and drought events in the Iberian Peninsula, using a multiscalar drought index, the standardized precipitation evapotranspiration index (SPEI), at various timescales. The effects of the occurrence of dry episodes on wheat yields were analyzed, on regional spatial scale for two subperiods (1929-1985 and 1986-2012). The results show that in western areas, wheat yield is positively affected by dryer conditions, whereas the opposite happens in eastern areas. The winter months have a bigger influence in the west while the east is more dependent on the spring and summer months. Moreover, in the period of 1986-2012, the simultaneous occurrence of low-yield anomalies and dry events reaches values close to 100 % over many provinces. Results suggest that May and June have a strong control on wheat yield, namely, for longer timescales (9 to 12 months). A shift in the dependence of wheat yields on climatic droughts is evidenced by the increase in the area with positive correlation and the decrease in area with negative correlation between wheat yields and SPEI, probably due to the increase of dry events.

  19. [Chronic recurrent parotitis].

    PubMed

    Zenk, J; Koch, M; Klintworth, N; Iro, H

    2010-03-01

    Chronic recurrent parotitis is a non-obstructive disease with episodes of mostly painful swelling of the gland. It is categorized into a juvenile and an adult form, even without clear information on its actual origin. As to the etiology of the juvenile form, genetic factors and duct malformations as well as bacterial infections are discussed. Very rarely a complete lymphatic transformation of the gland might take place. Juvenile chronic recurrent parotitis is self-limiting in about 90% of all cases, as patients grow up. The diagnosis is based on patient history and clinical findings. Sonography is the imaging method of choice. Sialendoscopy shows a typical whitish pattern of the ducts in juvenile disease. Strictures or stenoses are typical for the adult form. The therapy of choice is gland massage and sialagogues, in addition to the administration of antibiotics. In more severe cases sialendoscopy together with rinsing of the ducts and instillation of cortisone are indicated. Total parotidectomy remains the last choice and is rarely necessary.

  20. Volcanic Eruptions and Climate

    NASA Technical Reports Server (NTRS)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

    Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

  1. Recurrence theorems: A unified account

    SciTech Connect

    Wallace, David

    2015-02-15

    I discuss classical and quantum recurrence theorems in a unified manner, treating both as generalisations of the fact that a system with a finite state space only has so many places to go. Along the way, I prove versions of the recurrence theorem applicable to dynamics on linear and metric spaces and make some comments about applications of the classical recurrence theorem in the foundations of statistical mechanics.

  2. Interannual Variability in the SE Levantine Basin 1995-2009

    NASA Astrophysics Data System (ADS)

    Zodiatis, George; Samuel-Rhoads, Yianna; Hayes, Daniel; Stylianou, Stavros; Gertman, Isaac; Georgiou, Georgios; Soloyov, Dmitry

    2010-05-01

    Knowledge of the hydrographic character of the Levantine Basin increased dramatically with the few seasonal Physical Oceanography of the Eastern Mediterranean (POEM) cruises in the SE Levantine Basin during the 1980s. They first depicted the existence of a multi-pole gyre, the Shikmona gyre. This gyre consisted of three eddies, with the Cyprus warm core eddy being the most pronounced, and an offshore cross basin current, the Mid Mediterranean Jet (MMJ). From 1995 until 2009, a considerably larger amount of seasonal in-situ data was collected from various observing platforms in the SE Levantine Basin. These data were collected mostly within the framework of the Cyprus Basin Oceanography (CYBO) cruises and secondarily by some other collaborative cruises and projects (such as CYCLOPS, MFSPP, MFSTEP, HaiSec, etc). During the same timeframe (1995-2009), increases in sea surface temperatures (SSTs) have been recorded to occur globally, with the Mediterranean SSTs rising about twice as much as those of the global oceans. In-situ and satellite remote sensing SST data for the period 1995-2009 were analysed and compared in the Levantine Basin. Further, SST and sea surface salinity (SSS) in-situ profiles from the above oceanographic cruises in this region were extracted from the Bythos database, in order to study the interannual thermohaline variability at the surface layer (0-10m), along with the variability of the Cyprus warm core eddy and the MMJ. These long term seasonally collected in-situ datasets reveal that the dominant and permanent flow feature in the SE Levantine is the Cyprus warm core eddy, which undergoes significant seasonal and interannual fluctuations in terms of its shape, size, intensity and location. The Atlantic Water (AW) in the SE Levantine is very well pronounced during summer periods, mostly at the sub-surface depths, below the thermocline, with salinity as low as 38.65-38.9. The MMJ is documented to transfer the AW eastward within the Levantine Basin

  3. Interannual oscillations and the weather over the North Atlantic

    NASA Astrophysics Data System (ADS)

    Feliks, Yizhak; Robertson, Andrew; Ghil, Michael

    2014-05-01

    The interannual oscillations have small amplitude with respect to the amplitudes of mid-latitude weather systems, like the winter cyclones. Thus it is not clear how these weak oscillations affect the weather systems. We explore this problem over the North Atlantic basin (NAB) by using the NCEP-NCAR reanalysis on a 2.5x2.5 degree grid for 1949-2012. We partition the North Atlantic into into four rectangular regions, divided by the 45 W meridian and the 40 N parallel. The winter average (DJFM) of the daily transient kinetic energy of the geostrophic wind (GTKE) over these four quadrants was calculated at the 500-hPa level. The mean of the GTKE over each region shows prominent year-to-year variability. The GTKE variability contains three oscillatory modes, with periods of 8.7, 5.6 and 2.7 years. These oscillatory modes are highly significant statistically and close in period to the interannual oscillations found in the North Atlantic Oscillation (NAO) index (Feliks et al. 2010, 2013). The correlations between the winter average of the NAO index and the spatial GTKE average in the four quadrants are: NE = 0.82, SE = -0.79, NW = 0.54 and SW = -0.56. So the role of the NAO is significantly more prominent as expected in the eastern NAB, and there is a phase opposition between the northern and southern quadrants. The absolute value of the GTKE in the NE is larger by an order of magnitude than in the SE. The interannual oscillatory modes of the GTKE in the NE and those of the NAO index are completely synchronized. Only in the winter does the spatial average of the GTKE over any quadrant exceed a threshold value of 220 m2s-2; this value corresponds roughly to the presence of a strong winter storm within the given quadrant. The number of days during which the GTKE exceeds this value changes significantly from year to year; it is between 6 to 83 days in the NE quadrant and between 0 and 1 day in the SE quadrant. This number of days correlates with the NAO index at 0.85; the

  4. Recent climate-induced variations in terrestrial carbon cycle over tropics: A model simulation

    NASA Astrophysics Data System (ADS)

    Ichii, K.; Nemani, R. R.; Hashimoto, H.

    2003-12-01

    Tropical forests accounts for about 20 percent of the world terrestrial carbon and one-third of global terrestrial NPP. Atmospheric inversion studies show that additional factors such as CO2 fertilization and climate changes, should work as a carbon sink despite of CO2 emission due to deforestation in tropical regions. However, responses of tropical ecosystems to environmental changes and current carbon sink mechanisms are still unknown. The goal of this study is (1) to characterize the climate influences on tropical carbon cycle such as GPP, NPP and NEP, and (2) to analyze recent interannual variations in terrestrial carbon cycle over tropics. We investigated the relationship between climate factors (temperature, precipitation, radiation, and VPD) and several carbon cycle components, and analyzed recent carbon cycle variations over tropics using Biome BGC with NCEP reanalysis climate data from 1982 to 1999. In tropical ecosystems, interannual variations in GPP are mainly explained by radiation variations, and temperature and precipitation variation are secondary important. NPP and NEP interannual variations are primarily determined by temperature variation, and radiation came as a secondary important factors. Precipitation, which was considered as an important climate factor that control interannual variations in carbon cycle in tropics, has little effects on interannual variation in tropical carbon cycle possibly because of abundant rainfall. Then, recent interannual variations in terrestrial carbon cycle over tropics were analyzed from 1982-1999. Tropics show gradual increases in GPP, NPP, and NEP at a rate of several percent per recent 18 years with large drop in 1998. Both climate change and CO2 fertilization have impact on recent enhancement of terrestrial carbon uptake. Of all climate factors, radiation-induced enhancement shows important role in enhancing CO2 uptake over Amazon. On the other hand, variations in precipitation and vapor pressure did not make

  5. Interdecadal and Interannual Variability of Winter Precipitation in Southeast China

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Interdecadal variability of observed winter (DJF) precipitation in Southeast China (1961 to 2010) is characterized by the first EOF of the three-monthly Standardized Precipitation Index (SPI) subjected to a 9-year running mean, while the differences from the original describe the interannual fluctuations. For interdecadal time scales the dominating spatial modes represent monopole features over Southeast China involving the Arctic Oscillation (AO) and the sea surface temperature (SST) anomalies over western Pacific. Dynamic composite analysis (based on NCEP/NCAR and ERA-40 reanalyzes) reveals the following results: (i) Interdecadal SPI-variations show a trend from a dryer state in the 1970s via an increase during the 1980s towards stabilization of wetter conditions commencing with the 1990s. (ii) In mid-to-high latitudes the weakened southward flow of polar airmasses induces low-level warming over Eurasia due to stronger Arctic Oscillation (AO) by warmer zonal temperature advection. This indicates that the precipitation increase in Southeast is attributed circulation anomalies over mid-to-high latitudes which are related to AO. (iii) The abnormal moisture flux along the southwestern boundary of the abnormal anticyclone over south Japan (and its anomalous south-easterlies) is modulated by the sea surface temperature (SST) anomalies over Western Pacific; a positive (negative) SST anomaly will strengthen (weaken) the warm and moist air flow, leading to abundant (less) precipitation in Southeast China. This demonstrates the collaborative effect of AO and SST anomalies in determining the nonlinear trend observed in winter precipitation over Southeast China. For interannual time scales the dominating spatial pattern also represents monopole patterns. Composite analysis (with resampling test) of the associated circulation anomalies reveals the following results: (i) The wet (dry) winter is a result of the strengthened (weakened) northward warm moist air over east coast of

  6. Abemaciclib in Children With DIPG or Recurrent/Refractory Solid Tumors

    ClinicalTrials.gov

    2017-02-10

    Diffuse Intrinsic Pontine Glioma; Brain Tumor, Recurrent; Solid Tumor, Recurrent; Neuroblastoma, Recurrent, Refractory; Ewing Sarcoma, Recurrent, Refractory; Rhabdomyosarcoma, Recurrent, Refractory; Osteosarcoma, Recurrent, Refractory; Rhabdoid Tumor, Recurrent, Refractory

  7. Landslide occurrences and recurrence intervals of heavy rainfalls in Japan

    NASA Astrophysics Data System (ADS)

    Saito, H.; Uchida, T.; Matsuyama, H.; Korup, O.

    2015-12-01

    Dealing with predicted increases in extreme weather conditions due to climate change requires robust knowledge about controls on rainfall-triggered landslides. This study developed the probable rainfall database from weather radar data, and analyzed the potential correlation between the landslide magnitude-frequency and the recurrence interval of the heavy rainfall across Japan. We analyzed 4,744 rainfall-induced landslides (Saito et al., 2014, Geology), 1 to 72 h rainfalls, and soil water index (SWI). We then estimated recurrence intervals for these rainfall parameters using a Gumbel distribution with jackknife fitting. Results showed that the recurrence intervals of rainfall events which caused landslides (<10^3 m^3) were less than 10 yr across Japan. The recurrence intervals increased with increases in landslide volumes. With regard to the landslides larger than 10^5 m^3, recurrence intervals of the rainfall events were more than 100 yr. These results suggest that recurrence intervals of heavy rainfalls are important for assessing regional landslide hazard in Japan.

  8. Global Ocean Evaporation: How Well Can We Estimate Interannual to Decadal Variability?

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Bosilovich, Michael G.; Roberts, Jason B.; Wang, Hailan

    2015-01-01

    Evaporation from the world's oceans constitutes the largest component of the global water balance. It is important not only as the ultimate source of moisture that is tied to the radiative processes determining Earth's energy balance but also to freshwater availability over land, governing habitability of the planet. Here we focus on variability of ocean evaporation on scales from interannual to decadal by appealing to three sources of data: the new MERRA-2 (Modern-Era Retrospective analysis for Research and Applications -2); climate models run with historical sea-surface temperatures, ice and atmospheric constituents (so-called AMIP experiments); and state-of-the-art satellite retrievals from the Seaflux and HOAPS (Hamburg Ocean-Atmosphere Parameters and Fluxes from Satellite) projects. Each of these sources has distinct advantages as well as drawbacks. MERRA-2, like other reanalyses, synthesizes evaporation estimates consistent with observationally constrained physical and dynamical models-but data stream discontinuities are a major problem for interpreting multi-decadal records. The climate models used in data assimilation can also be run with lesser constraints such as with SSTs and sea-ice (i.e. AMIPs) or with additional, minimal observations of surface pressure and marine observations that have longer and less fragmentary observational records. We use the new ERA-20C reanalysis produced by ECMWF embodying the latter methodology. Still, the model physics biases in climate models and the lack of a predicted surface energy balance are of concern. Satellite retrievals and comparisons to ship-based measurements offer the most observationally-based estimates, but sensor inter-calibration, algorithm retrieval assumptions, and short records are dominant issues. Our strategy depends on maximizing the advantages of these combined records. The primary diagnostic tool used here is an analysis of bulk aerodynamic computations produced by these sources and uses a first

  9. Influence of Soil Moisture on the Asian and African Monsoons. Part II: Interannual Variability.

    NASA Astrophysics Data System (ADS)

    Douville, H.

    2002-04-01

    The relevance of soil moisture (SM) for simulating the interannual climate variability has not been much investigated until recently. Much more attention has been paid on SST anomalies, especially in the Tropics where the El Niño-Southern Oscillation represents the main mode of variability. In the present study, ensembles of atmospheric integrations based on the Action de Recherche Petit Echelle Grande Echelle (ARPEGE) climate model have been performed for two summer seasons: 1987 and 1988, respectively. The aim is to compare the relative impacts of using realistic boundary conditions of SST and SM on the simulated variability of the Asian and African monsoons. Besides control runs with interactive SM, sensitivity tests have been done in which SM is relaxed toward a state-of-the-art SM climatology, either globally or regionally over the monsoon domain. The simulations indicate that the variations of the Asian monsoon between 1987 and 1988 are mainly driven by SST anomalies. This result might be explained by the strong teleconnection with the ENSO and by a weak SM-precipitation feedback over south Asia (Part I of the study). The influence of SM is more obvious over Africa. The model needs both realistic SST and SM boundary conditions to simulate the observed variability of the Sahelian monsoon rainfall. The positive impact of the SM relaxation is not only due to a local mechanism whereby larger surface evaporation leads to larger precipitation. The best results are obtained when the relaxation is applied globally, suggesting that remote SM impacts also contribute to the improved simulation of the precipitation variability. A relationship between the Sahelian rainfall anomalies and the meridional wind anomalies over North Africa points out the possible influence of the Northern Hemisphere midlatitudes. The comparison of the low- and midtropospheric anomalies in the various pairs of experiments indicates that SM anomalies can trigger stationary waves over Europe, and

  10. Forcing of polar motion in the Chandler frequency band: An opportunity to evaluate interannual climate variations

    NASA Astrophysics Data System (ADS)

    Plag, H.-P.; Chao, B. F.; Gross, R. S.; Van Dam, T.

    The Earth rotates about its axis once per day but does not do so uniformly. The length of the day changes by as much as a millisecond from day to day and the Earth wobbles as it rotates. That the Earth should wobble was predicted by the Swiss mathematician Leonhard Euler in 1765, but it was not until 1891 that the wobbling motion of the Earth was detected by the American astronomer Seth Carlo Chandler, Jr. In fact, Chandler observed that the Earth has two distinct wobbles, one with an annual period and the other with a 14-month period. The annual wobble is a forced motion of the Earth caused by seasonal variations in the atmosphere, oceans, and hydrosphere.

  11. Digital Atlas and Evaluation of the Influence of Inter-Annual Variability on Climate Analyses

    DTIC Science & Technology

    2003-09-01

    Abstracts, Institute Nationale di Oceanografia e di Geofisica Sperimentale-OGS, Trieste, Italy 2001 р. 65 Unesco 1993: Manual of quality control procedures for validation of oceanographic data, IOC UNESCO, pp.436. 995

  12. The influence of volcanic stratospheric aerosols on interannual global climate variations. Ph.D. Thesis

    SciTech Connect

    Andsager, K.M.

    1992-12-31

    A qualitative physical mechanism has been proposed to explain the forcing of the EI Nino/Southern Oscillation (ENSO) by low-latitude volcanic stratospheric aerosols. This mechanism is based on the normal global annual cycle resulting from the normal annual cycle in the distribution of incoming solar radiation. The presence of a volcanic stratospheric aerosol, which backscatters incoming solar radiation, is hypothesized to trigger the ENSO through an amplification of the normal annual decrease in wind strength and corresponding increase in sea surface temperatures (SST) in the eastern tropical Pacific Ocean. The observational evidence for an association between the record of volcanic eruptions and SST and the Southern Oscillation Index (SOI, Tahiti SLP minus Darwin SLP) over the last 120 years is examined using superposed epoch analysis. Composites using as key dates low-latitude volcanic eruptions suggest that these eruptions are followed by statistically significantly warm sea surface temperatures at least at the 1 percent level, if not higher, with the greatest warming generally occurring in the first three seasons after the eruption. Satellite data on the distribution of recent volcanic aerosols suggests that an aerosol must only be present over the tropics (about 20 deg S to 20 deg N) to trigger an ENSO event. For the physical mechanism by which an ENSO event may be triggered by a volcanic stratospheric aerosol, these results and the results of recent computer modeling studies imply the need for a shift away from past emphasis on surface cooling and SLP anomalies and toward consideration of stratospheric warming and changes in energy storage and transport.

  13. Assessment of climatic factors influence on interannual changes in the global surface air temperature

    NASA Astrophysics Data System (ADS)

    Gusakova, Maria; Karlin, Lev

    2014-05-01

    A model to assess a number of factors such as TSI, albedo, cloudiness and greenhouse gases including water vapour affecting global surface air temperature (SAT) changes has been developed. To develop the model solar energy transformation in the atmosphere and the other radiation fluxes transformation were investigated. It's a common knowledge that some part of the incoming solar energy is reflected into space by the Earth's surface, aerosol and cloud particles. A contribution of these components to changes in the reflected solar energy was assessed on the basis of developed linear parameterization. During the period of 2001 - 2010, clouds were found to be the basic contributor to the changes in reflected shortwave radiation. Some part of outgoing terrestrial radiation is retained in the atmosphere by greenhouse gases, water vapour and cloudiness. A contribution of these components to changes in the absorbed longwave radiation was assessed on the basis of developed linear parameterization. It was estimated that the contribution of water vapour was dominant during the analyzed period. The developed parameterization of global albedo made it possible to assess the contribution of TSI to global SAT changes. Making use of the parameterizations listed above the model has been improved. The model calculations showed that the our projections of global SAT to 2030 were lower than IPCC estimates.

  14. Interannual Variability of Sea Surface Height over the Black Sea: Relation to Climatic Patterns

    DTIC Science & Technology

    2008-01-01

    eastern and western basins, reflecting variations in the corresponding gyres. A joint examination of SSH and sea surface temperature (SST) indicates...available altimeter data. SSH variability reveals distinct maxima in the eastern and western basins, reflecting variations in the corresponding gyres. A...change resulted from variations in thermocline or mixed layer depth. One important factor is to determine whether sea level varia- tions are mainly

  15. Recurrence plots revisited

    NASA Astrophysics Data System (ADS)

    Casdagli, M. C.

    1997-09-01

    We show that recurrence plots (RPs) give detailed characterizations of time series generated by dynamical systems driven by slowly varying external forces. For deterministic systems we show that RPs of the time series can be used to reconstruct the RP of the driving force if it varies sufficiently slowly. If the driving force is one-dimensional, its functional form can then be inferred up to an invertible coordinate transformation. The same results hold for stochastic systems if the RP of the time series is suitably averaged and transformed. These results are used to investigate the nonlinear prediction of time series generated by dynamical systems driven by slowly varying external forces. We also consider the problem of detecting a small change in the driving force, and propose a surrogate data technique for assessing statistical significance. Numerically simulated time series and a time series of respiration rates recorded from a subject with sleep apnea are used as illustrative examples.

  16. Recurrent vulvovaginal candidiasis.

    PubMed

    Sobel, Jack D

    2016-01-01

    Recurrent vulvovaginal candidiasis (RVVC) is a common cause of significant morbidity in women in all strata of society affecting millions of women worldwide. Previously, RVVC occurrence was limited by onset of menopause but the widespread use of hormone replacement therapy has extended the at-risk period. Candida albicans remains the dominant species responsible for RVVC, however optimal management of RVVC requires species determination and effective treatment measures are best if species-specific. Considerable progress has been made in understanding risk factors that determine susceptibility to RVVC, particularly genetic factors, as well as new insights into normal vaginal defense immune mechanisms and their aberrations in RVVC. While effective control of RVVC is achievable with the use of fluconazole maintenance suppressive therapy, cure of RVVC remains elusive especially in this era of fluconazole drug resistance. Vaccine development remains a critical challenge and need.

  17. Quantifying the increasing sensitivity of power systems to climate variability

    NASA Astrophysics Data System (ADS)

    Bloomfield, H. C.; Brayshaw, D. J.; Shaffrey, L. C.; Coker, P. J.; Thornton, H. E.

    2016-12-01

    Large quantities of weather-dependent renewable energy generation are expected in power systems under climate change mitigation policies, yet little attention has been given to the impact of long term climate variability. By combining state-of-the-art multi-decadal meteorological records with a parsimonious representation of a power system, this study characterises the impact of year-to-year climate variability on multiple aspects of the power system of Great Britain (including coal, gas and nuclear generation), demonstrating why multi-decadal approaches are necessary. All aspects of the example system are impacted by inter-annual climate variability, with the impacts being most pronounced for baseload generation. The impacts of inter-annual climate variability increase in a 2025 wind-power scenario, with a 4-fold increase in the inter-annual range of operating hours for baseload such as nuclear. The impacts on peak load and peaking-plant are comparably small. Less than 10 years of power supply and demand data are shown to be insufficient for providing robust power system planning guidance. This suggests renewable integration studies—widely used in policy, investment and system design—should adopt a more robust approach to climate characterisation.

  18. Interannual variations of surface winds over China marginal seas

    NASA Astrophysics Data System (ADS)

    Sun, Che; Yan, Xiaomei

    2012-11-01

    In a study of surface monsoon winds over the China marginal seas, Sun et al. (2012) use singular value decomposition method to identify regional dominant modes and analyze their interdecadal variability. This paper continues to evaluate the interannual variability of each dominant mode and its relation to various atmospheric, oceanic and land factors. The findings include: 1) The intensity of the winter monsoon over the East China Sea is highly correlated with the Siberian High intensity and anti-correlated with the latitudinal position of the Aleutian Low as well as the rainfall in eastern China, Korean Peninsula and Japan; 2) The western Pacific subtropical high is significantly correlated with the summer monsoon intensity over the East China Sea and anti-correlated with the summer monsoon over the South China Sea; 3) The winter monsoon in a broad zonal belt through the Luzon Strait is dominated by the ENSO signal, strengthening in the La Niña phase and weakening in the El Niño phase. This inverse relation exhibits interdecadal shift with a period of weak correlation in the 1980s; 4) Analysis of tidal records validates the interdecadal weakening of the East Asian summer monsoon and reveals an atmospheric bridge that conveys the ENSO signal into the South China Sea via the winter monsoon.

  19. Interannual variability in ozone removal by a temperate deciduous forest

    NASA Astrophysics Data System (ADS)

    Clifton, O. E.; Fiore, A. M.; Munger, J. W.; Malyshev, S.; Horowitz, L. W.; Shevliakova, E.; Paulot, F.; Murray, L. T.; Griffin, K. L.

    2017-01-01

    The ozone (O3) dry depositional sink and its contribution to observed variability in tropospheric O3 are both poorly understood. Distinguishing O3 uptake through plant stomata versus other pathways is relevant for quantifying the O3 influence on carbon and water cycles. We use a decade of O3, carbon, and energy eddy covariance (EC) fluxes at Harvard Forest to investigate interannual variability (IAV) in O3 deposition velocities (vd,O3). In each month, monthly mean vd,O3 for the highest year is twice that for the lowest. Two independent stomatal conductance estimates, based on either water vapor EC or gross primary productivity, vary little from year to year relative to canopy conductance. We conclude that nonstomatal deposition controls the substantial observed IAV in summertime vd,O3 during the 1990s over this deciduous forest. The absence of obvious relationships between meteorology and vd,O3 implies a need for additional long-term, high-quality measurements and further investigation of nonstomatal mechanisms.

  20. Interannual variability in stratiform cloudiness and sea surface temperature

    SciTech Connect

    Norris, J.R.; Leovy, C.B.

    1994-12-01

    Marine stratiform cloudiness (MSC)(stratus, stratocumulus, and fog) is widespread over subtropical oceans west of the continents and over midlatitude oceans during summer, the season when MSC has maximum influence on surface downward radiation and is most influenced by boundary-layer processes. Long-term datasets of cloudiness and sea surface teperature (SST) from surface observations from 1952 to 1981 are used to examine interannual variations in MSC and SST. Linear correlations of anomalies in seasonal MSC amount with seasonal SST anomalies are negative and significant in midlatitude and eastern subtropical oceans, especially during summer. Significant negative correlations between SST and nimbostratus and nonprecipitating midlevel cloudiness are also observed at midlatitudes during summer, suggesting that summer storm tracks shift from year to year following year-to-year meridional shifts in the SST gradient. Over the 30-yr period, there are significant upward trends in MSC amount over the northern midlatitude oceans and a significant downward trend off the coast of California. The highest correlations and trends occur where gradients in MSC and SST are strongest. During summer, correlations between SST and MSC anomalies peak at zero lag in midlatitudes where warm advection prevails, but SST lags MSC in subtropical regions where cold advection predominates. This difference is attributed to a tendency for anomalies in latent heat flux to compensate anomalies in surface downward radiation in warm advection regions but not in cold advection regions.

  1. Interannual variability of rainfall characteristics over southwestern Madagascar

    NASA Astrophysics Data System (ADS)

    Randriamahefasoa, T. S. M.; Reason, C. J. C.

    2016-01-01

    The interannual variability of daily frequency of rainfall [>1 mm/day] and heavy rainfall [>30 mm/day] is studied for the southwestern region of Madagascar, which is relatively arid compared to the rest of the island. Attention is focused on the summer rainy season from December to March at four stations (Morondava, Ranohira, Toliara and Taolagnaro), whose daily rainfall data covering the period 1970-2000 were obtained from the Madagascar Meteorological Service. El Niño Southern Oscillation (ENSO) was found to have a relatively strong correlation with wet day frequency at each station and, particularly, for Toliara in the extreme southwest. In terms of seasonal rainfall totals, most El Niño (La Niña) summers receive below (above) average amounts. An ENSO connection with heavy rainfall events was less clear. However, for heavy rainfall events, the associated atmospheric circulation displays a Southern Annular Mode-like pattern throughout the hemisphere. For ENSO years and the neutral seasons 1979/80, 1981/82 which had large anomalies in wet day frequency, regional atmospheric circulation patterns consisted of strong anomalies in low-level moisture convergence and uplift over and near southwestern Madagascar that made conditions correspondingly more or less favourable for rainfall. Dry (wet) summers in southern Madagascar were also associated with an equatorward (poleward) displacement of the ITCZ in the region.

  2. Interannual variability of the Atlantic Cold Tongue heat budget

    NASA Astrophysics Data System (ADS)

    Planton, Yann; Voldoire, Aurore; Giordani, Hervé; Caniaux, Guy

    2015-04-01

    The processes governing the Atlantic Cold Tongue (ACT) development are now better understood, but the mechanisms of its interannual variability are still unclear. The aim of the present study is to explore the mechanisms leading to the cold tongue formation during cold and warm ACT events. Cold and warm ACT events are classified statistically from several datasets following a criteria derived from Richter et al. (2013) and slightly adapted. This classification allows to analyse composites of extreme events. In particular, composites of the mixed layer heat budget have been calculated, computed online in a forced global ocean model. This mixed layer heat budget is a good tool to identify the oceanic processes which control the formation of the ACT and its variability. The results show that the turbulent mixing at the base of the mixed layer plays a dominant role controlling the ACT formation. Cold (warm) events are associated with strong increase (decrease) of the turbulent mixing from march to July. In addition horizontal the advection anomalies are opposite during cold and warm events in June-July. The positive (negative) anomalies during cold (warm) events tend to damp (enhance) the ACT. During warm events, the advection process is responsible of the ACT formation with almost the same intensity as when averaged over all.

  3. Delineating recurrent fish spawning habitats in the North Sea

    NASA Astrophysics Data System (ADS)

    Lelièvre, S.; Vaz, S.; Martin, C. S.; Loots, C.

    2014-08-01

    The functional value of spawning habitats makes them critically important for the completion of fish life cycles and spawning grounds are now considered to be “essential habitats”. Inter-annual fluctuations in spawning ground distributions of dab (Limanda Limanda), plaice (Pleuronectes platessa), cod (Gadus morhua) and whiting (Merlangius merlangus) were investigated in the southern North Sea and eastern English Channel, from 2006 to 2009. The preferential spawning habitats of these species were modelled using generalised linear models, with egg distribution being used as proxy of spawners' location. Egg spatial and temporal distributions were explored based on six environmental variables: sea surface temperature and salinity, chlorophyll a concentration, depth, bedstress and seabed sediment types. In most cases, egg density was found to be strongly related to these environmental variables. Egg densities were positively correlated with shallow to intermediate depths having low temperature and relatively high salinity. Habitat models were used to map annual, i.e. 2006 to 2009, winter spatial distributions of eggs, for each species separately. Then, annual maps were combined to explore the spatial variability of each species' spawning grounds, and define recurrent, occasional, rare and unfavourable spawning areas. The recurrent spawning grounds of all four species were located in the south-eastern part of the study area, mainly along the Dutch and German coasts. This study contributes knowledge necessary to the spatial management of fishery resources in the area, and may also be used to identify marine areas with particular habitat features that need to be preserved.

  4. Regional Climate Modeling: Progress, Challenges, and Prospects

    SciTech Connect

    Wang, Yuqing; Leung, Lai R.; McGregor, John L.; Lee, Dong-Kyou; Wang, Wei-Chyung; Ding, Yihui; Kimura, Fujio

    2004-12-01

    Regional climate modeling with regional climate models (RCMs) has matured over the past decade and allows for meaningful utilization in a broad spectrum of applications. In this paper, latest progresses in regional climate modeling studies are reviewed, including RCM development, applications of RCMs to dynamical downscaling for climate change assessment, seasonal climate predictions and climate process studies, and the study of regional climate predictability. Challenges and potential directions of future research in this important area are discussed, with the focus on those to which less attention has been given previously, such as the importance of ensemble simulations, further development and improvement of regional climate modeling approach, modeling extreme climate events and sub-daily variation of clouds and precipitation, model evaluation and diagnostics, applications of RCMs to climate process studies and seasonal predictions, and development of regional earth system models. It is believed that with both the demonstrated credibility of RCMs’ capability in reproducing not only monthly to seasonal mean climate and interannual variability but also the extreme climate events when driven by good quality reanalysis and the continuous improvements in the skill of global general circulation models (GCMs) in simulating large-scale atmospheric circulation, regional climate modeling will remain an important dynamical downscaling tool for providing the needed information for assessing climate change impacts and seasonal climate predictions, and a powerful tool for improving our understanding of regional climate processes. An internationally coordinated effort can be developed with different focuses by different groups to advance regional climate modeling studies. It is also recognized that since the final quality of the results from nested RCMs depends in part on the realism of the large-scale forcing provided by GCMs, the reduction of errors and improvement in

  5. Treatment of juvenile recurrent parotitis.

    PubMed

    Katz, Philippe; Hartl, Dana M; Guerre, Agnès

    2009-12-01

    Juvenile recurrent parotitis (JRP) can be a debilitating illness in children. Knowing how to recognize and diagnose it for early treatment avoids recurrences that could lead to significant destruction of the glandular parenchyma. This article discusses the various therapeutic modalities proposed in the literature (medical treatment or sialendoscopy) and describes the authors' treatment of choice of combining antibiotics and iodinated oil sialography.

  6. Recurrent Bell's palsy in pregnancy.

    PubMed

    Deshpande, A D

    1990-09-01

    A case of recurrent Bell's palsy occurring in two successive pregnancies in a 37-year-old woman is presented. The causes of facial nerve paralysis of the lower motor neurone type are discussed. The rate of recurrence of Bell's palsy during pregnancy is unknown. Treatment with corticosteroids of Bell's palsy during pregnancy poses the threat of possible side effects on the fetus.

  7. Climate change impacts on agriculture in Apulia

    NASA Astrophysics Data System (ADS)

    Lionello, Piero; Congedi, Letizia; Reale, Marco; Scarascia, Luca; Tanzarella, Annalisa

    2013-04-01

    This study describes the evolution of climate from recent past to the next decades in Apulia, a region in Southern Italy, and estimates its future impacts on its main agricultural products. The analysis is based on instrumental data, on an ensemble of climate projections and on a linear regression model linking typical Mediterranean products (wheat, olive oil and wine) to seasonal values of temperature and precipitation. In the past decades, wheat, olive oil and wine production records (the three main agricultural products in Apulia) show large inter-annual variabilityand an important fraction of it is explained by past climate variability. Regional Climate Model simulations show a large acceleration of the warming rate and a decrease of precipitation in the period 2001-2050. Results (considering no adaptation of crops) suggest that climate evolution in the first half of the 21st century would decrease wine production, have a small effect on wheat and increase olive oil production.

  8. MECHANISMS OF CONVECTION-INDUCED MODULATION OF PASSIVE TRACER INTERHEMISPHERIC TRANSPORT INTERANNUAL VARIABILITY

    EPA Science Inventory

    Interannual variations of tropical convection impact atmospheric circulation and influence year-to-year variations of the transport of trace constituents in the troposphere. This study examines how two modes of convective variability-anomalous intensification and meridional disp...

  9. Predictability and prediction of tropical cyclones on daily to interannual time scales

    NASA Astrophysics Data System (ADS)

    Belanger, James Ian

    regions. Following the TC predictability studies, a proof-of-concept operational forecast system for North Atlantic TCs is presented for daily to intraseasonal time scales. Findings from the predictability studies are used in conjunction with recently developed forecast calibration techniques to render the VarEPS and ECMFS forecasts more useful in an operational setting. The proposed combination of bias-calibrated regional probabilistic forecast guidance along with objectively-defined measures of confidence is a new way of providing TC forecasts on intraseasonal time scales. On interannual time scales, the predictability of TCs is examined by considering their relationship with tropical Atlantic easterly waves. First, a set of easterly wave climatologies for the Climate Forecast System-Reanalysis, ERA-Interim, ERA-40, and NCEP/NCAR Reanalysis are developed using a new easterly wave tracking algorithm based on 700 hPa curvature relative vorticity anomalies. From the reanalysis-derived easterly wave climatologies, a moderately positive and statistically significant relationship is seen with tropical Atlantic TCs, suggesting that approximately 20-30% of the total variance in the number of TCs on interannual time scales may be explained by the frequency of easterly waves. In relation to large-scale climate modes, the Atlantic Multidecadal Oscillation (AMO) and Atlantic Meridional Mode (AMM) exhibit the strongest positive covariability with Atlantic easterly wave frequency. Besides changes in the number of easterly waves, the intensification efficiency of easterly waves, which is the percentage of waves that induce North Atlantic TC formation, has also been evaluated. These findings offer a plausible physical explanation for the recent increase in the number of NATL TCs, as it has been concomitant with an increasing trend in both the number of tropical Atlantic easterly waves and intensification efficiency. In addition, the easterly wave-tropical cyclone pathway is likely an

  10. Recurrent Aphthous Stomatitis: A Review

    PubMed Central

    Saleh, Dahlia; Miller, Richard A.

    2017-01-01

    Aphthous stomatitis is a painful and often recurrent inflammatory process of the oral mucosa that can appear secondary to various well-defined disease processes. Idiopathic recurrent aphthous stomatitis is referred to as recurrent aphthous stomatitis. The differential diagnosis for recurrent aphthous ulcerations is extensive and ranges from idiopathic benign causes to inherited fever syndromes, to connective tissue disease, or even inflammatory bowel diseases. A thorough history and review of systems can assist the clinician in determining whether it is related to a systemic inflammatory process or truly idiopathic. Management of aphthous stomatitis is challenging. For recurrent aphthous stomatitis or recalcitrant aphthous stomatitis from underlying disease, first-line treatment consists of topical medications with use of systemic medications as necessary. Herein, the authors discuss the differential diagnosis and treatment ladder of aphthous stomatitis as described in the literature. PMID:28360966

  11. Recurrent Aphthous Stomatitis: A Review.

    PubMed

    Edgar, Natalie Rose; Saleh, Dahlia; Miller, Richard A

    2017-03-01

    Aphthous stomatitis is a painful and often recurrent inflammatory process of the oral mucosa that can appear secondary to various well-defined disease processes. Idiopathic recurrent aphthous stomatitis is referred to as recurrent aphthous stomatitis. The differential diagnosis for recurrent aphthous ulcerations is extensive and ranges from idiopathic benign causes to inherited fever syndromes, to connective tissue disease, or even inflammatory bowel diseases. A thorough history and review of systems can assist the clinician in determining whether it is related to a systemic inflammatory process or truly idiopathic. Management of aphthous stomatitis is challenging. For recurrent aphthous stomatitis or recalcitrant aphthous stomatitis from underlying disease, first-line treatment consists of topical medications with use of systemic medications as necessary. Herein, the authors discuss the differential diagnosis and treatment ladder of aphthous stomatitis as described in the literature.

  12. Aspen Global Change Institute (AGCI) Interdisciplinary Science Workshop: Decadal Climate Prediction; Aspen, CO; June 22-28, 2008

    SciTech Connect

    Katzenberger, John

    2010-03-12

    Decadal prediction lies between seasonal/interannual forecasting and longer-term climate change projections, and focuses on time-evolving regional climate conditions over the next 10?30 yr. Numerous assessments of climate information user needs have identified this time scale as being important to infrastructure planners, water resource managers, and many others. It is central to the information portfolio required to adapt effectively to and through climatic changes.

  13. Climate variation explains a third of global crop yield variability

    NASA Astrophysics Data System (ADS)

    Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

    2015-01-01

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32-39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability.

  14. Climate variation explains a third of global crop yield variability.

    PubMed

    Ray, Deepak K; Gerber, James S; MacDonald, Graham K; West, Paul C

    2015-01-22

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32-39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability.

  15. Climate variation explains a third of global crop yield variability

    PubMed Central

    Ray, Deepak K.; Gerber, James S.; MacDonald, Graham K.; West, Paul C.

    2015-01-01

    Many studies have examined the role of mean climate change in agriculture, but an understanding of the influence of inter-annual climate variations on crop yields in different regions remains elusive. We use detailed crop statistics time series for ~13,500 political units to examine how recent climate variability led to variations in maize, rice, wheat and soybean crop yields worldwide. While some areas show no significant influence of climate variability, in substantial areas of the global breadbaskets, >60% of the yield variability can be explained by climate variability. Globally, climate variability accounts for roughly a third (~32–39%) of the observed yield variability. Our study uniquely illustrates spatial patterns in the relationship between climate variability and crop yield variability, highlighting where variations in temperature, precipitation or their interaction explain yield variability. We discuss key drivers for the observed variations to target further research and policy interventions geared towards buffering future crop production from climate variability. PMID:25609225

  16. Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2.

    PubMed

    Keppel-Aleks, Gretchen; Wolf, Aaron S; Mu, Mingquan; Doney, Scott C; Morton, Douglas C; Kasibhatla, Prasad S; Miller, John B; Dlugokencky, Edward J; Randerson, James T

    2014-11-01

    The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO2) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO2 anomalies. Here we examined how the temporal evolution of CO2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO2 variability. We developed atmospheric CO2 patterns from each of these mechanisms during 1997-2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9 ± 0.4 Pg C yr(-1) K(-1). These results underscore the need for accurate attribution of the drivers of CO2 variability prior to using contemporary observations to constrain long-term ESM responses.

  17. Can the Tibetan Plateau snow cover influ