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1

Tides and Decadal Variability  

NASA Technical Reports Server (NTRS)

This paper reviews the mechanisms by which oceanic tides and decadal variability in the oceans are connected. We distinguish between variability caused by tides and variability observed in the tides themselves. Both effects have been detected at some level. The most obvious connection with decadal timescales is through the 18.6-year precession of the moon's orbit plane. This precession gives rise to a small tide of the same period and to 18.6-year modulations in the phase and amplitudes of short-period tides. The 18.6-year "node tide" is very small, no more than 2 cm anywhere, and in sea level data it is dominated by the ocean's natural Variability. Some authors have naively attributed climate variations with periods near 19 years directly to the node tide, but the amplitude of the tide is too small for this mechanism to be operative. The more likely explanation (Loder and Garrett, JGR, 83, 1967-70, 1978) is that the 18.6-y modulations in short-period tides, especially h e principal tide M2, cause variations in ocean mixing, which is then observed in temperature and other climatic indicators. Tidally forced variability has also been proposed by some authors, either in response to occasional (and highly predictable) tidal extremes or as a nonlinear low-frequency oscillation caused by interactions between short-period tides. The former mechanism can produce only short-duration events hardly more significant than normal tidal ranges, but the latter mechanism can in principle induce low-frequency oscillations. The most recent proposal of this type is by Keeling and Whorf, who highlight the 1800-year spectral peak discovered by Bond et al. (1997). But the proposal appears contrived and should be considered, in the words of Munk et al. (2002), "as the most likely among unlikely candidates."

Ray, Richard D.

2003-01-01

2

Measurement Biases Explain Discrepancies between the Observed and Simulated Decadal Variability of Surface Incident Solar Radiation  

NASA Astrophysics Data System (ADS)

Observations have reported a widespread dimming of surface incident solar radiation (Rs) from the 1950s to the 1980s and a brightening afterwards. However, none of the state-of-the-art earth system models, including those from the Coupled Model Intercomparison Project phase 5 (CMIP5), could successfully reproduce the dimming/brightening rates over China. We find that the decadal variability of observed Rs may have important errors due to instrument sensitivity drifting and instrument replacement. While sunshine duration (SunDu), which is a robust measurement related to Rs, is nearly free from these problems. We estimate Rs from SunDu with a method calibrated by the observed Rs at each station. SunDu-derived Rs declined over China by -2.8 (with a 95% confidence interval of -1.9 to -3.7) W m-2 per decade from 1960 to 1989, while the observed Rs declined by -8.5 (with a 95% confidence interval of -7.3 to -9.8) W m-2 per decade. The former trend was duplicated by some high-quality CMIP5 models, but none reproduced the latter trend.

Wang, Kaicun

2014-08-01

3

Measurement Biases Explain Discrepancies between the Observed and Simulated Decadal Variability of Surface Incident Solar Radiation  

PubMed Central

Observations have reported a widespread dimming of surface incident solar radiation (Rs) from the 1950s to the 1980s and a brightening afterwards. However, none of the state-of-the-art earth system models, including those from the Coupled Model Intercomparison Project phase 5 (CMIP5), could successfully reproduce the dimming/brightening rates over China. We find that the decadal variability of observed Rs may have important errors due to instrument sensitivity drifting and instrument replacement. While sunshine duration (SunDu), which is a robust measurement related to Rs, is nearly free from these problems. We estimate Rs from SunDu with a method calibrated by the observed Rs at each station. SunDu-derived Rs declined over China by ?2.8 (with a 95% confidence interval of ?1.9 to ?3.7) W m?2 per decade from 1960 to 1989, while the observed Rs declined by ?8.5 (with a 95% confidence interval of ?7.3 to ?9.8) W m?2 per decade. The former trend was duplicated by some high-quality CMIP5 models, but none reproduced the latter trend. PMID:25142756

Wang, Kaicun

2014-01-01

4

Measurement biases explain discrepancies between the observed and simulated decadal variability of surface incident solar radiation.  

PubMed

Observations have reported a widespread dimming of surface incident solar radiation (Rs) from the 1950s to the 1980s and a brightening afterwards. However, none of the state-of-the-art earth system models, including those from the Coupled Model Intercomparison Project phase 5 (CMIP5), could successfully reproduce the dimming/brightening rates over China. We find that the decadal variability of observed Rs may have important errors due to instrument sensitivity drifting and instrument replacement. While sunshine duration (SunDu), which is a robust measurement related to Rs, is nearly free from these problems. We estimate Rs from SunDu with a method calibrated by the observed Rs at each station. SunDu-derived Rs declined over China by -2.8 (with a 95% confidence interval of -1.9 to -3.7) W m(-2) per decade from 1960 to 1989, while the observed Rs declined by -8.5 (with a 95% confidence interval of -7.3 to -9.8) W m(-2) per decade. The former trend was duplicated by some high-quality CMIP5 models, but none reproduced the latter trend. PMID:25142756

Wang, Kaicun

2014-01-01

5

Internannual variability of regional enhancements of tropospheric ozone determined from two decades of satellite observations  

NASA Astrophysics Data System (ADS)

Data derived form the empirically corrected tropospheric ozone residual (TOR) technique using TOMS (Total Ozone Mapping Spectrometer) and SBUV (So lar Backscatter UltraViolet) satellite measurements provide unique insight into the regional sources and transport of tropospheric ozone as well as how the resultant distribution varies interannually. Relative to the previously published TOR climatologies using TOMS and SAGE (Stratospheric Aerosol and Gas Experiment) data, the current technique shows better-defined high ozone regions over eastern China, northeast India, and the eastern United States. With the much greater spatial and temporal resolution available from the empirical-correction technique, shifts in seasonal patterns of tropospheric ozone are observed and will be related to the interannual variability of prevailing meteorological conditions. These long-term records will be analyzed in the context of the El Niño/Southern Oscillation (ENSO) where preliminary analysis suggests that pollution amounts over northeastern India is dependent on the phase of the ENSO. Other regional sources of tropospheric pollution will also be discussed and analyzed in the context of large scale flow regimes.

Fishman, J.; Creilson, J.; Balok, A.

6

Decadal rainfall variability modes in observed rainfall records over East Africa and their relations to historical sea surface temperature changes  

NASA Astrophysics Data System (ADS)

SummaryDetailed knowledge about the long-term interface of climate and rainfall variability is essential for managing agricultural activities in Eastern African countries. To this end, the space-time patterns of decadal rainfall variability modes over East Africa and their predictability potentials using Sea Surface Temperature (SST) are investigated. The analysis includes observed rainfall data from 1920 to 2004 and global SSTs for the period 1950-2004. Simple correlation, trend and cyclical analyses, Principal Component Analysis (PCA) with VARIMAX rotation and Canonical Correlation Analysis (CCA) are employed. The results show decadal signals in filtered observed rainfall record with 10 years period during March-May (MAM) and October-December (OND) seasons. During June-August (JJA), however, cycles with 20 years period are common. Too much/little rainfall received in one or two years determines the general trend of the decadal mean rainfall. CCA results for MAM showed significant positive correlations between the VARIMAX-PCA of SST and the canonical component time series over the central equatorial Indian Ocean. Positive loadings were spread over the coastal and Lake Victoria regions while negative loading over the rest of the region with significant canonical correlation skills. For the JJA seasons, Atlantic SSTs had negative loadings centred on the tropical western Atlantic Ocean associated with the wet/dry regimes over western/eastern sectors. The highest canonical correlation skill between OND rainfall and the Pacific SSTs showed that El Niño/La Niña phases are associated with wet/dry decades over the region.

Omondi, P.; Awange, J. L.; Ogallo, L. A.; Okoola, R. A.; Forootan, E.

2012-09-01

7

Decadal Variability of the Kuroshio Extension: Observations and an Eddy-Resolving Model Hindcast*  

E-print Network

). In both the OFES hindcast and satellite altimeter observations, low-frequency sea surface height (SSH. Introduction The Kuroshio Extension (KE) is a swift eastward inertial jet formed after the Kuroshio separates

Xie, Shang-Ping

8

Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables  

NASA Astrophysics Data System (ADS)

This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. The canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, with the main focus on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time-scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising the big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s-1) and lowest during winter dormancy (1 mm s-1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained the high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). The set of common environmental variables and terpene concentrations used in multivariate analysis were able to predict the observed average seasonal variation in total and non-stomatal deposition but failed to explain the inter-annual differences, suggesting that some still unknown mechanisms might be involved in determining the inter-annual variability. Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. The results clearly showed the importance of several non-stomatal removal mechanisms. Unknown chemical compounds or processes correlating with monoterpene concentrations, including potentially reactions at the surfaces, contribute to non-stomatal sink term.

Rannik, Ü.; Altimir, N.; Mammarella, I.; Bäck, J.; Rinne, J.; Ruuskanen, T. M.; Hari, P.; Vesala, T.; Kulmala, M.

2012-12-01

9

Changes in the mesoscale variability and in extreme sea levels over two decades as observed by satellite altimetry  

NASA Astrophysics Data System (ADS)

data set of precise radar altimeter sea surface heights obtained from the same 10 day repeat ground track has been analyzed to determine the magnitude of change in the ocean "mesoscale" variability over two decades. Trends in the standard deviation of sea surface height variability each year are found to be small (typically ˜0.5 percent/yr) throughout the global ocean. Trends in positive and negative extreme sea level in each region are in general found to be similar to those of mean sea level, with some small regional exceptions. Generalized Extreme Value Distribution (GEVD) analysis also demonstrates that spatial variations in the statistics of extreme positive sea levels are determined largely by the corresponding spatial variations in mean sea level changes, and are related to regional modes of the climate system such as the El Niño-Southern Oscillation. Trends in the standard deviation of along-track sea level gradient variability are found to be close to zero on a global basis, with regional exceptions. Altogether our findings suggest an ocean mesoscale variability that displays little change when considered over an extended period of two decades, but that is superimposed on a spatially and temporally varying signal of mean sea level change.

Woodworth, Philip L.; Menéndez, Melisa

2015-01-01

10

Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables  

NASA Astrophysics Data System (ADS)

This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. Canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, focusing on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time- scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s-1) and lowest during winter dormancy (1 mm s-1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. This was also confirmed by the statistical analysis that did not link measured sesquiterpene concentration with ozone deposition. It was concluded that chemical reactions with monoterpenes, or other removal mechanisms such as surface reactions, play a role as ozone non-stomatal sink inside canopy.

Rannik, Ü.; Altimir, N.; Mammarella, I.; Bäck, J.; Rinne, J.; Ruuskanen, T. M.; Hari, P.; Vesala, T.; Kulmala, M.

2012-05-01

11

Re-Examination of the Observed Decadal Variability of Earth Radiation Budget Using Altitude-Corrected ERBE/ERBS Nonscanner WFOV Data  

NASA Technical Reports Server (NTRS)

This paper gives an update on the observed decadal variability of Earth Radiation Budget using the latest altitude-corrected Earth Radiation Budget Experiment (ERBE)/Earth Radiation Budget Satellite (ERBS) Nonscanner Wide Field of View (WFOV) instrument Edition3 dataset. The effects of the altitude correction are to modify the original reported decadal changes in tropical mean (20N to 20S) longwave (LW), shortwave (SW), and net radiation between the 1980s and the 1990s from 3.1/-2.4/-0.7 to 1.6/-3.0/1.4 Wm(sup -2) respectively. In addition, a small SW instrument drift over the 15-year period was discovered during the validation of the WFOV Edition3 dataset. A correction was developed and applied to the Edition3 dataset at the data user level to produce the WFOV Edition3_Rev1 dataset. With this final correction, the ERBS Nonscanner observed decadal changes in tropical mean LW, SW, and net radiation between the 1980s and the 1990s now stand at 0.7/-2.1/1.4 Wm(sup -2), respectively, which are similar to the observed decadal changes in the HIRS Pathfinder OLR and the ISCCP FD record; but disagree with the AVHRR Pathfinder ERB record. Furthermore, the observed interannual variability of near-global ERBS WFOV Edition3_Rev1 net radiation is found to be remarkably consistent with the latest ocean heat storage record for the overlapping time period of 1993 to 1999. Both data sets show variations of roughly 1.5 Wm(sup -2) in planetary net heat balance during the 1990s.

Wong, Takmeng; Wielicki, Bruce A.; Lee, Robert B.; Smith, G. Louis; Bush, Kathryn A.

2005-01-01

12

Variability of Antarctic ozone loss in the last decade (2004-2013): high resolution simulations compared to Aura MLS observations  

NASA Astrophysics Data System (ADS)

A detailed analysis of the polar ozone loss processes during ten recent Antarctic winters is presented with high resolution Mimosa-Chim model simulations and high frequency polar vortex observations from the Aura Microwave Limb Sounder (MLS) instrument. Our model results for the Antarctic winters 2004-2013 show that chemical ozone loss starts in the edge region of the vortex at equivalent latitudes (EqLs) of 65-69° S in mid-June/July. The loss progresses with time at higher EqLs and intensifies during August-September over the range 400-600 K. The loss peaks in late September/early October, where all EqLs (65-83°) show similar loss and the maximum loss (>2 ppmv [parts per million by volume]) is found over a broad vertical range of 475-550 K. In the lower stratosphere, most winters show similar ozone loss and production rates. In general, at 500 K, the loss rates are about 2-3 ppbv sh-1 (parts per billion by volume/sunlit hour) in July and 4-5 ppbv sh-1 in August/mid-September, while they drop rapidly to zero by late September. In the middle stratosphere, the loss rates are about 3-5 ppbv sh-1 in July-August and October at 675 K. It is found that the Antarctic ozone hole (June-September) is controlled by the halogen cycles at about 90-95% (ClO-ClO, BrO-ClO, and ClO-O) and the loss above 700 K is dominated by the NOx cycle at about 70-75%. On average, the Mimosa-Chim simulations show that the very cold winters of 2005 and 2006 exhibit a maximum loss of ~3.5 ppmv around 550 K or about 149-173 DU over 350-850 K and the warmer winters of 2004, 2010, and 2012 show a loss of ~2.6 ppmv around 475-500 K or 131-154 DU over 350-850 K. The winters of 2007, 2008, and 2011 were moderately cold and thus both ozone loss and peak loss altitudes are between these two ranges (3 ppmv around 500 K or 150 ± 10 DU). The modeled ozone loss values are in reasonably good agreement with those estimated from Aura MLS measurements, but the model underestimates the observed ClO, largely due to the slower vertical descent in the model during spring.

Kuttippurath, J.; Godin-Beekmann, S.; Lefèvre, F.; Santee, M. L.; Froidevaux, L.; Hauchecorne, A.

2014-11-01

13

Decadal variability in Floods and Extreme Rainfall  

NASA Astrophysics Data System (ADS)

Decadal variability in climate extremes associated with floods is of particular interest for infrastructure development and for insurance programs. From an analysis of US data we note that changes in insurance rates and in the construction of flood control infrastructure emerge soon after a period where there is a high incidence of regional flooding. This leads to the question of whether there is clustering in the incidence of anomalous flooding (or its absence) at decadal scales. The direct examination of this question from streamflow data is often clouded by the modification of flows by the construction of dams and other infrastructure to control floods, especially over a large river basin. Consequently, we explore the answer to this question through the analysis of both extreme rainfall and flood records. Spectral and time domain methods are used to identify the nature of decadal variability and its potential links to large scale climate.

Lall, Upmanu; Cioffi, Francesco; Devineni, Naresh; Lu, Mengqian

2014-05-01

14

Intensification of decadal and multi-decadal sea level variability in the western tropical Pacific during recent decades  

NASA Astrophysics Data System (ADS)

Previous studies have linked the rapid sea level rise (SLR) in the western tropical Pacific (WTP) since the early 1990s to the Pacific decadal climate modes, notably the Pacific Decadal Oscillation in the north Pacific or Interdecadal Pacific Oscillation (IPO) considering its basin wide signature. Here, the authors investigate the changing patterns of decadal (10-20 years) and multidecadal (>20 years) sea level variability (global mean SLR removed) in the Pacific associated with the IPO, by analyzing satellite and in situ observations, together with reconstructed and reanalysis products, and performing ocean and atmosphere model experiments. Robust intensification is detected for both decadal and multidecadal sea level variability in the WTP since the early 1990s. The IPO intensity, however, did not increase and thus cannot explain the faster SLR. The observed, accelerated WTP SLR results from the combined effects of Indian Ocean and WTP warming and central-eastern tropical Pacific cooling associated with the IPO cold transition. The warm Indian Ocean acts in concert with the warm WTP and cold central-eastern tropical Pacific to drive intensified easterlies and negative Ekman pumping velocity in western-central tropical Pacific, thereby enhancing the western tropical Pacific SLR. On decadal timescales, the intensified sea level variability since the late 1980s or early 1990s results from the "out of phase" relationship of sea surface temperature anomalies between the Indian and central-eastern tropical Pacific since 1985, which produces "in phase" effects on the WTP sea level variability.

Han, Weiqing; Meehl, Gerald A.; Hu, Aixue; Alexander, Michael A.; Yamagata, Toshio; Yuan, Dongliang; Ishii, Masayoshi; Pegion, Philip; Zheng, Jian; Hamlington, Benjamin D.; Quan, Xiao-Wei; Leben, Robert R.

2014-09-01

15

Food Price Volatility and Decadal Climate Variability  

NASA Astrophysics Data System (ADS)

The agriculture system is under pressure to increase production every year as global population expands and more people move from a diet mostly made up of grains, to one with more meat, dairy and processed foods. Weather shocks and large changes in international commodity prices in the last decade have increased pressure on local food prices. This paper will review several studies that link climate variability as measured with satellite remote sensing to food price dynamics in 36 developing countries where local monthly food price data is available. The focus of the research is to understand how weather and climate, as measured by variations in the growing season using satellite remote sensing, has affected agricultural production, food prices and access to food in agricultural societies. Economies are vulnerable to extreme weather at multiple levels. Subsistence small holders who hold livestock and consume much of the food they produce are vulnerable to food production variability. The broader society, however, is also vulnerable to extreme weather because of the secondary effects on market functioning, resource availability, and large-scale impacts on employment in trading, trucking and wage labor that are caused by weather-related shocks. Food price variability captures many of these broad impacts and can be used to diagnose weather-related vulnerability across multiple sectors. The paper will trace these connections using market-level data and analysis. The context of the analysis is the humanitarian aid community, using the guidance of the USAID Famine Early Warning Systems Network and the United Nation's World Food Program in their response to food security crises. These organizations have worked over the past three decades to provide baseline information on food production through satellite remote sensing data and agricultural yield models, as well as assessments of food access through a food price database. Econometric models and spatial analysis are used to describe the connection between shocks and food prices, and to demonstrate the importance of these metrics in overall outcomes in food-insecure communities.

Brown, M. E.

2013-12-01

16

Decadal to multidecadal variability and the climate change background  

Microsoft Academic Search

Three prominent quasi-global patterns of variability and change are observed using the Met Office's sea surface temperature (SST) analysis and almost independent night marine air temperature analysis. The first is a global warming signal that is very highly correlated with global mean SST. The second is a decadal to multidecadal fluctuation with some geographical similarity to the El Niño–Southern Oscillation

David Parker; Chris Folland; Adam Scaife; Jeff Knight; Andrew Colman; Peter Baines; Buwen Dong

2007-01-01

17

Advances in Understanding Decadal Climate Variability  

NASA Technical Reports Server (NTRS)

Recently, a joint Brazil-France-U.S. program, known as PIRATA (Pilot Research moored Array in the Tropical Atlantic), was proposed to begin the deployment of moored measurement platforms in the tropical Atlantic in order to enhance the existing observational data base and subsequent understanding of the processes by which the ocean and atmosphere couple in key regions of the tropical Atlantic Ocean. Empirical studies have suggested that there are strong relationships between tropical Atlantic upper ocean variability, SST, ocean-atmosphere coupling and regional climate variability. During the early 1980's a coordinated set of surface wind, subsurface thermal structure, and subsurface current observations were obtained as part of the U.S.-France SEQUAL- FOCAL process experiment designed to observe the seasonal response of the tropical Atlantic Ocean to surface forcing. Since that time, however, the observational data base for the tropical Atlantic Ocean has disintegrated to a few shiptracks measuring ocean temperatures and a small collection of tide gauge stations measuring sea level. A more comprehensive set of observations, modeling and empirical studies is now in order to make progress on understanding the regional climate variability. The proposed PIRATA program will use mooring platforms similar to the tropical Pacific Ocean TAO array to measure surface fluxes of momentum and heat and the corresponding changes in the upper ocean thermal structure. It is anticipated that the oceanic data from this monitoring array will also be used in a predictive mode for initialization studies of regional coupled climate models. Of particular interest are zonal and meridional modes of ocean-atmosphere variability within the tropical Atlantic basin that have significant impacts on the regional climate of the bordering continents.

Busalaacchi, Antonio J.

1998-01-01

18

Advances in Understanding Decadal Climate Variability  

NASA Technical Reports Server (NTRS)

Recently, a joint Brazil-France-U.S. program, known as PIRATA (Pilot Research moored Array in the Tropical Atlantic), was proposed to begin the deployment of moored measurement platforms in the tropical Atlantic in order to enhance the existing observational data base and subsequent understanding of the processes by which the ocean and atmosphere couple in key regions of the tropical Atlantic Ocean. Empirical studies have suggested that there are strong relationships between tropical Atlantic upper ocean variability, SST, ocean-atmosphere coupling and regional climate variability. During the early 1980's a coordinated set of surface wind, subsurface thermal structure, and subsurface current observations were obtained as part of the U.S.-France SEQUAL-FOCAL process experiment designed to observe the seasonal response of the tropical Atlantic Ocean to surface forcing. Since that time, however, the observational data base for the tropical Atlantic Ocean has disintegrated to a few ship-tracks measuring ocean temperatures and a small collection of tide gauge stations measuring sea level. A more comprehensive set of observations, modeling and empirical studies is now in order to make progress on understanding the regional climate variability. The proposed PIRATA program will use mooring platforms similar to the tropical Pacific Ocean TAO array to measure surface fluxes of momentum and heat and the corresponding changes in the upper ocean thermal structure. It is anticipated that the oceanic data from this monitoring array will also be used in a predictive mode for initialization studies of regional coupled climate models. Of particular interest are zonal and meridional modes of ocean-atmosphere variability within the tropical Atlantic basin that have significant impacts on the regional climate of the bordering continents.

Busalacchi, Antonio J.

1999-01-01

19

Contribution of solar radiation to decadal temperature variability over land  

PubMed Central

Global air temperature has become the primary metric for judging global climate change. The variability of global temperature on a decadal timescale is still poorly understood. This paper examines further one suggested hypothesis, that variations in solar radiation reaching the surface (Rs) have caused much of the observed decadal temperature variability. Because Rs only heats air during the day, its variability is plausibly related to the variability of diurnal temperature range (daily maximum temperature minus its minimum). We show that the variability of diurnal temperature range is consistent with the variability of Rs at timescales from monthly to decadal. This paper uses long comprehensive datasets for diurnal temperature range to establish what has been the contribution of Rs to decadal temperature variability. It shows that Rs over land globally peaked in the 1930s, substantially decreased from the 1940s to the 1970s, and changed little after that. Reduction of Rs caused a reduction of more than 0.2 °C in mean temperature during May to October from the 1940s through the 1970s, and a reduction of nearly 0.2 °C in mean air temperature during November to April from the 1960s through the 1970s. This cooling accounts in part for the near-constant temperature from the 1930s into the 1970s. Since then, neither the rapid increase in temperature from the 1970s through the 1990s nor the slowdown of warming in the early twenty-first century appear to be significantly related to changes of Rs. PMID:23980136

Wang, Kaicun; Dickinson, Robert E.

2013-01-01

20

Elements of tropical Pacific decadal variability  

E-print Network

of the period from 1965 to 1999. Model results show Pacific basin decadal changes, including the prominent 1976-77 climate shift, in agreement with previous research. The reanalysis indicates an evolution intrinsic to the tropical Pacific which propagates...

Fuckar, Neven-Stjepan

2003-01-01

21

Decadal Climate Variability over the North Pacific and North America: Dynamics and Predictability  

Microsoft Academic Search

The dynamics and predictability of decadal climate variability over the North Pacific and North America are investigated by analyzing various observational datasets and the output of a state of the art coupled ocean-atmosphere general circulation model that was integrated for 125 years. Both the observations and model results support the picture that the decadal variability in the region of interest

M. Latif; T. P. Barnett

1996-01-01

22

Anatomizing the Ocean's role in maintaining the pacific decadal variability  

NASA Astrophysics Data System (ADS)

The role of ocean dynamics in maintaining the Pacific Decadal Variability (PDV) was investigated based on simulation results from the Parallel Ocean Program (POP) ocean general circulation model developed at the Los Alamos National Laboratory (LANL). A long-term control simulation of the LANL-POP model forced by a reconstructed coupled wind stress field over the period 1949-2001 showed that the ocean model not only simulates a reasonable climatology, but also produces a climate variability pattern very similar to observed PDV. In the Equatorial Pacific (EP) region, the decadal warming is confined in the thin surface layer. Beneath the surface, a strong compensating cooling, accompanied by a basin-wide-scale overturning circulation in opposition to the mean flow, occurs in the thermocline layer. In the North Pacific (NP) region, the decadal variability nonetheless exhibits a relatively monotonous pattern, characterized by the dominance of anomalous cooling and eastward flows. A term balance analysis of the perturbation heat budget equation was conducted to highlight the ocean's role in maintaining the PDV-like variability over the EP and NP regions. The analyses showed that strong oceanic adjustment must occur in the equatorial thermocline in association with the anomalous overturning circulation in order to maintain the PDV-like variability, including a flattening of the equatorial thermocline slpoe and an enhancement of the upper ocean's stratification (stability), as the climate shifts from a colder regime toward a warmer one. On the other hand, the oceanic response in the extratropical region seems to be confined to the surface layer, without much participation from the subsurface oceanic dynamics.

Yu, Jia-Yuh; Chang, Cheng-Wei

2014-05-01

23

Chandra's First Decade Observing AR Lac  

NASA Astrophysics Data System (ADS)

X-ray observations of the eclipsing RS CVn-type binary AR Lacertae have been obtained every year from 1999 to 2008 with the Chandra High Resolution Camera imaging and spectroscopic detectors (HRC-I, HRC-S) as part of their gain and point spread function calibration. These represent the best quality data yet obtained on the long term variability of the X-ray emission of an RS CVn star, and are rendered especially valuable for the multi-epoch coverage of the AR Lac eclipses. The data are characterised by stochastic variability by factors of ˜2 on timescales of one to several ks, and by minor flaring events in which count rates are observed to be elevated by slightly larger factors. During primary eclipse, the X-ray count rate is generally observed at approximately 60% of its value outside of eclipse and during periods of relative quiescence. Little evidence for secondary eclipses is present in the data, reminiscent of earlier X-ray and EUV observations. The X-ray count rate modulation through the eclipses allow us to place an upper limit on the extent of a spherically symmetric coronae of about two stellar radii, the exact limit depending on the details of the coronal models and partition of emission between the component stars. We compare the observed Chandra count rates to earlier EUVE, EINSTEIN, EXOSAT and ROSAT observations and comment on the apparent lack of cyclic coronal activity on RS CVn-type binaries.

Ratzlaff, Peter; Drake, Jeremy J.; Durham, R. Nicholas; Kashyap, Vinay; Posson-Brown, Jennifer; Wargelin, Bradford J.

2009-09-01

24

A Decade of Satellite Ocean Color Observations  

NASA Technical Reports Server (NTRS)

After the successful Coastal Zone Color Scanner (CZCS, 1978-1986), demonstration that quantitative estimations of geophysical variables such as chlorophyll a and diffuse attenuation coefficient could be derived from top of the atmosphere radiances, a number of international missions with ocean color capabilities were launched beginning in the late 1990s. Most notable were those with global data acquisition capabilities, i.e., the Ocean Color and Temperature Sensor (OCTS 1996-1997), the Sea-viewing Wide Field-of-view Sensor (SeaWiFS, United States, 1997-present), two Moderate Resolution Imaging Spectroradiometers, (MODIS, United States, Terra/2000-present and Aqua/2002-present), the Global Imager (GLI, Japan, 2002-2003), and the Medium Resolution Imaging Spectrometer (MERIS, European Space Agency, 2002-present). These missions have provided data of exceptional quality and continuity, allowing for scientific inquiries into a wide variety of marine research topics not possible with the CZCS. This review focuses on the scientific advances made over the past decade using these data sets.

McClain, Charles R.

2009-01-01

25

Interannual and Decadal Variability of Summer Rainfall over South America  

NASA Technical Reports Server (NTRS)

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, the changes of the strength of the subtropical high and the associated surface wind are dynamically consistent with the distribution of local SST anomalies, suggesting the importance of the atmospheric forcing in the decadal time scale. The decadal mode also presents a weak summer monsoon in its positive phase, which reduces the moisture supply from the equatorial Atlantic and the Amazon Basin and results in negative rainfall anomalies over the central Andes and Gran Chaco. The long-term trend shows decrease of rainfall from the northwest coast to the southeast subtropical region and a southward shift of Atlantic ITCZ that leads to increased rainfall over northern and eastern Brazil. Our result shows a close link of this mode to the observed SST warming trend over the subtropical South Atlantic and a remote connection to the interdecadal SST variation over the extratropical North Atlantic found in previous studies.

Zhou, Jiayu; Lau, K.-M.

1999-01-01

26

Decadal Record of Satellite Carbon Monoxide Observations  

NASA Astrophysics Data System (ADS)

Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, chemical production, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern hemispheres along with regional trends for E. China, E. USA, Europe and India. Measurement and sampling methods for each of the instruments are discussed, and we show diagnostics for systematic errors in MOPITT trends. We find that all the satellite observations are consistent with a modest decreasing trend around -1%/year in total column CO over the Northern hemisphere for this time period. Decreasing trends in total CO column are observed for the United States, Europe and E. China with more than 2? significance. For India, the trend is also decreasing, but smaller in magnitude and less significant. Decreasing trends in surface CO have also been observed from measurements in the U.S. and Europe. Although less information is available for surface CO in China, there is a decreasing trend reported for Beijing. Some of the interannual variability in the observations can be explained by global fire emissions, and there may be some evidence of the global financial crisis in late 2008 to early 2009. But the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.

Worden, Helen; Deeter, Merritt; Frankenberg, Christian; George, Maya; Nichitiu, Florian; Worden, John; Aben, Ilse; Bowman, Kevin; Clerbaux, Cathy; Coheur, Pierre-Francois; de Laat, Jos; Warner, Juying; Drummond, James; Edwards, David; Gille, John; Hurtmans, Daniel; Ming, Luo; Martinez-Alonso, Sara; Massie, Steven; Pfister, Gabriele

2013-04-01

27

Arctic decadal variability from an idealized atmosphere-ice-ocean model: 2. Simulation of decadal oscillations  

Microsoft Academic Search

A simple model of the Arctic Ocean and Greenland Sea, coupled to a thermodynamic sea ice model and an atmospheric model, has been used to study decadal variability of the Arctic ice-ocean-atmosphere climate system. The motivating hypothesis is that the behavior of the modeled and ultimately the real climate system is auto-oscillatory with a quasi-decadal periodicity. This system oscillates between

Dmitry Dukhovskoy; Mark Johnson; Andrey Proshutinsky

2006-01-01

28

Foraminiferal radiocarbon record of northeast Pacific decadal subsurface variability  

NASA Astrophysics Data System (ADS)

The decadal dynamics of the subsurface North Pacific Ocean are largely inaccessible beyond sparse instrumental observations spanning the last 20 years. Here we present a ˜200 year long record of benthic foraminiferal radiocarbon (?14C), extracted at biennial resolution from the annually laminated sediments at the Santa Barbara Basin (SBB) depocenter (˜600 m). The close match between core top benthic foraminiferal ?14C values and the ?14C of seawater dissolved inorganic carbon (DIC) suggests that benthic foraminifera faithfully capture the bottom water radiocarbon concentrations, as opposed to that of the deeper (>0.5 cm) sediment porewater zone. The full time series of benthic foraminiferal ?14C displays significant variability on decadal timescales, with excursions on the order of 40‰. These excursions are overprinted by a unidirectional trend over the late 20th century that likely reflects the sedimentary incorporation of bomb radiocarbon (via remineralized particulate organic carbon). We isolate this trend by means of a one-dimensional oxidation model, which considers the possible contribution of remineralized particles to the total ambient carbon pool. This oxidation model also considers the possible influence of carbon with a variety of sources (ages). Though variable oxidation of preaged carbon could exert a strong influence on benthic foraminiferal radiocarbon variability, the totality of evidence points to the vertical density structure along the Southern California Margin (SCM) as the primary driver of the SBB benthic foraminiferal ?14C record. For example, intervals characterized by significantly lower ?14C values correspond to periods of enhanced upwelling and subsurface equatorward flow along the SCM.

Roach, Lydia D.; Charles, Christopher D.; Field, David B.; Guilderson, Thomas P.

2013-09-01

29

Decadal variability of Arctic climate: cyclonic and anticyclonic circulation regimes  

NASA Astrophysics Data System (ADS)

In this presentation we update our time series of the Arctic Ocean Oscillation (AOO) index and show decadal variability for 1946-present illustrated by decadal changes in different atmospheric, sea ice, oceanic and terrestrial parameters correlating with AOO. In particularly, in 2009, the wind-driven circulation regime can be characterized as cyclonic with a Beaufort Gyre that is significantly reduced in strength and a Trans-Polar drift that is effectively non-existent. This is the first time that an annual cyclonic circulation regime has been observed in the Arctic since 1997. The anticyclonic circulation regime that persisted through 2008 lasted at least 12 years instead of the typical 5-8 years (as reported in Proshutinsky and Johnson (1997) who analyzed statistics of Arctic circulation regimes between 1946 and 1989). The climatological seasonality of Arctic dynamics is anticyclonic ice and ocean circulation prevailing in winter and cyclonic circulation in summer. Since 2007, this seasonality has changed dramatically. In 2007, both summer and winter circulations were very strongly anticyclonic and resulted in the significant reduction of sea ice in the Arctic Ocean. In 2008, the winter circulation was strongly anticyclonic but summer circulation was unusual with a strong Beaufort Gyre and a strong cyclonic circulation cell north of the Laptev Sea. In 2009, the system reversed relative to climatology in both winter and summer: it was strongly anticyclonic in summer (instead of cyclonic circulation) and relatively strongly cyclonic in winter (instead of climatologically stable anticyclonic circulation). These conditions have significantly influenced the characteristics of the sea-ice cover, oceanic currents, and ocean freshwater and heat content observed during last decade of arctic warming.

Proshutinsky, A. Y.; Johnson, M. A.

2010-12-01

30

A simple coupled model of tropical Atlantic decadal climate variability  

NASA Astrophysics Data System (ADS)

A linear, zonally averaged model of the interaction between the tropical Atlantic (TA) atmosphere and ocean is presented. A balance between evaporation and meridional heat advection in the mixed layer determines the sea surface temperature tendency. The atmosphere is a fixed-depth, sub-cloud layer in which the specific humidity anomaly is determined by a steady-state balance between evaporation, meridional advection, and a parameterized humidity exchange with the free atmosphere. When the model is integrated, forced with observed surface wind anomalies from 1965 to the present, its simulation of the observed sea surface temperature (SST) is realistic and comparable to a simulation with a full ocean GCM. A statistical representation of surface winds and their relationship to the SST gradient across the equator is used to formulate and test a coupled model of their regional variability. Forced on both sides of the equator, in the trade-wind regions, with ``white-noise'' windspeed perturbations, the SST-wind relationship in the near-equatorial region feeds back positively on existing SST anomalies and gives rise to decadal variability.

Kushnir, Yochanan; Seager, Richard; Miller, Jennifer; Chiang, John C. H.

2002-12-01

31

Atmospheric response to the North Atlantic Ocean variability on seasonal to decadal time scales  

E-print Network

Atmospheric response to the North Atlantic Ocean variability on seasonal to decadal time scales in the North Atlantic region at seasonal to decadal time scales. At the seasonal scale, the air-sea interaction model and observations, the North Atlantic horseshoe SST anomaly pattern is in part generated

D'Andrea, Fabio

32

Multi-Decadal Variability of West African Rainfall in  

E-print Network

and Sahel rain reasonable § Indian SST and Sahel rain poorly simulation ­ often wrong sign §WhyMulti-Decadal Variability of West African Rainfall in CMIP5 Simulations Elinor R. Martin and Chris in troposphere stability and E-W circulation #12;Datasets §Precipitation: CRU (1901-2009): gauge only §SST: Had

Martin, Elinor R.

33

Variable stars across the observational HR diagram  

E-print Network

An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude diagram, is also presented. Some of the progresses performed in the field of variable stars during the last decade are briefly summarized, and future projects that will improve our knowledge of variable stars are mentioned.

Laurent Eyer; Nami Mowlavi

2007-12-21

34

Tropical Pacific Observing for the Next Decade  

NASA Astrophysics Data System (ADS)

More than 60 scientists and program officials from 13 countries met at the Scripps Institution of Oceanography for the Tropical Pacific Observing System (TPOS) 2020 Workshop. The workshop, although motivated in part by the dramatic decline of NOAA's Tropical Atmosphere Ocean (TAO) buoy reporting from mid-2012 to early 2014 (see http://www.bloomberg.com/news/2014-03-07/aging-el-nino-buoys-getting-fixed-as-weather-forecasts-at-risk.html), evaluated the needs for tropical Pacific observing and initiated efforts to develop a more resilient and integrative observing system for the future.

Legler, David M.; Hill, Katherine

2014-06-01

35

Decadal-Interdecadal SST Variability and Regional Climate Teleconnections  

NASA Technical Reports Server (NTRS)

Dominant modes of decadal and interdecadal SST variability and their impacts on summertime rainfall variability over East Asia and the North America are studied. Two dominant modes of interdecadal SST variability, one associated with El Nino-like warming in the global oceans and one with an east-west seesaw variation in the equatorial Pacific have been identified. The first mode is associated in part with a long-term warming trend in the topical oceans and cooling over the northern Pacific. The second mode suggests an westward shift and strengthening of the Walker circulation from 1960s to the 1980s. Over East Asian, the first SST mode is correlated with reduced rainfall in northern China and excessive rainfall in central China. This SST mode is also associated with the tendency for increased rainfall over the midwest region, and reduced rainfall over the east Coast of the US. The results suggest a teleconnection pattern which links the occurrences of drought and floods over the Asian monsoon and the US summertime time climate. This teleconnection is likely to be associated with decadal variability of the East Asian jetstream, which are affected by strong land surface heating over the Siberian region, as well as El Nino-like SST forcings. The occurrences of major droughts and floods in the East Asian and US continent in recent decades are discussed in light of the above teleconnection patterns.

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

2001-01-01

36

Tree-ring estimates of Pacific decadal climate variability  

Microsoft Academic Search

Decadal-scale oscillatory modes of atmosphere-ocean variability have recently been identified in instrumental studies of\\u000a the Pacific sector. The regime shift around 1976 is one example of such a fluctuation, which has been shown to have significantly\\u000a impacted climate and the environment along the coastline of the western N and S Americas. The length of meteorological data\\u000a for the Pacific and

R. D'Arrigo; R. Villalba; G. Wiles

2001-01-01

37

Multi-Decadal Variability of Colorado River Basin Streamflow  

NASA Astrophysics Data System (ADS)

Conventional water resource planning and management are based upon the assumption that past run-off records are indicative of future hydrologic conditions. The severe and sustained nature of the recent drought in the Southwestern United States has underscored the limitation of this planning approach. Furthermore, a growing collection of scientific literature indicates that anthropogenic climate change may further dry the region and strain its water resources. Thus, developing tools and strategies to address streamflow variability, is critical for effective water management in regions such as the Colorado River Basin. A crucial first step toward this end is the understanding of streamflow variability at multi-decadal time scales, driven by large scale climate features such as El Nino Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Atlantic Multi-decadal Oscillation (AMO), etc. Here, a systematic analysis of basin-wide natural streamflow and paleo-reconstructed flows in the Colorado River Basin is presented, using time domain principal component analysis (PCA) and spectral methods based on wavelets and a multi-taper method. The dominant patterns of variability are related to global sea surface temperatures (SSTs) to identify potential large scale climate features that drive the variability. Results indicate that the first two PCs explain approximately 60% of the total streamflow variance in the Basin. The first PC, which is a predominantly Upper Basin signal, correlates strongly with Atlantic Ocean SSTs and shows an AMO pattern, while the second PC has distinct ties to the Pacific Ocean, reminiscent of PDO and ENSO patterns. The spectral analyses of the leading PCs indicate strong coherence with the corresponding indices of the aforementioned climate forcings. The spectrum of the first PC displays a strong signal at 10-15 year and 60-70 year periodicities. Spectral analysis of paleo-reconstructed Upper Basin streamflow indicates that these periodicities are modulated, especially the decadal signal being modulated at a 75-year time scale. These results provide insight into the multi-decadal variability of Colorado River streamflow. Furthermore, they will have considerable utility in realistic simulation of near-term streamflows and consequently, efficient planning and management of water resources in the Colorado River Basin.

Nowak, K. C.; Rajagopalan, B.; Hoerling, M.; Zagona, E. A.

2010-12-01

38

Societal Adaptation to Decadal Climate Variability in the United States  

NASA Astrophysics Data System (ADS)

CRCES Workshop on Societal Impacts of Decadal Climate Variability in the United States, 26-28 April 2007, Waikoloa, Hawaii The search for evidence of decadal climatic variability (DCV) has a very long history. In the past decade, a research community has coalesced around a series of roughly biennial workshops that have emphasized description of past DCV events; their causes and their ``teleconnections'' responsible for droughts, floods, and warm and cold spells around the world; and recently, the predictability of DCV events. Researchers studying climate change put great emphasis on prospective impacts, but the DCV community has yet to do so. To begin rectifying this deficiency, a short but ambitious workshop was convened in Waikoloa, near Kona, Hawaii, from 26-28 April 2007. This workshop, sponsored by the Center for Research on the Changing Earth System (CRCES), NOAA, the U.S. Geological Survey, and the U.S. Army Corps of Engineers, brought together climatologists and sectoral specialists representing agriculture, water resources, economics, the insurance industry, and developing country interests.

Rosenberg, Norman J.; Mehta, Vikram M.; Olsen, J. Rolf; von Storch, Hans; Varady, Robert G.; Hayes, Michael J.; Wilhite, Donald

2007-10-01

39

Atmospheric Blocking and Atlantic Multi-Decadal Ocean Variability  

NASA Technical Reports Server (NTRS)

Based on the 20th century atmospheric reanalysis, winters with more frequent blocking, in a band of blocked latitudes from Greenland to Western Europe, are found to persist over several decades and correspond to a warm North Atlantic Ocean, in-phase with Atlantic multi-decadal ocean variability. Atmospheric blocking over the northern North Atlantic, which involves isolation of large regions of air from the westerly circulation for 5 days or more, influences fundamentally the ocean circulation and upper ocean properties by impacting wind patterns. Winters with clusters of more frequent blocking between Greenland and western Europe correspond to a warmer, more saline subpolar ocean. The correspondence between blocked westerly winds and warm ocean holds in recent decadal episodes (especially, 1996-2010). It also describes much longer-timescale Atlantic multidecadal ocean variability (AMV), including the extreme, pre-greenhouse-gas, northern warming of the 1930s-1960s. The space-time structure of the wind forcing associated with a blocked regime leads to weaker ocean gyres and weaker heat-exchange, both of which contribute to the warm phase of AMV.

Haekkinen, Sirpa; Rhines, Peter B.; Worthlen, Denise L.

2011-01-01

40

Atmospheric Blocking and Atlantic Multi-Decadal Ocean Variability  

NASA Technical Reports Server (NTRS)

Atmospheric blocking over the northern North Atlantic involves isolation of large regions of air from the westerly circulation for 5-14 days or more. From a recent 20th century atmospheric reanalysis (1,2) winters with more frequent blocking persist over several decades and correspond to a warm North Atlantic Ocean, in-phase with Atlantic multi-decadal ocean variability (AMV). Ocean circulation is forced by wind-stress curl and related air/sea heat exchange, and we find that their space-time structure is associated with dominant blocking patterns: weaker ocean gyres and weaker heat exchange contribute to the warm phase of AMV. Increased blocking activity extending from Greenland to British Isles is evident when winter blocking days of the cold years (1900-1929) are subtracted from those of the warm years (1939-1968).

Hakkinen, Sirpa; Rhines, Peter B.; Worthen, Denise L.

2011-01-01

41

Evaluating SODA for Indo-Pacific Ocean decadal climate variability studies  

NASA Astrophysics Data System (ADS)

Estimates of changes in upper ocean temperature, heat content, and sea level are dependent on the coverage of subsurface observations in space and time. Historically, these data are sparse, which has limited our understanding of ocean climate variability and change mechanisms. Ocean state estimates, which effectively represent a model synthesis and integration of the available observations, including internal observations in the ocean and surface forcing, help to address the inhomogeneity of sparse observations in space and time. Here we evaluate the representativeness of ocean state estimates from the Simple Ocean Data Assimilation Version 2.2.4 (SODA) data for studying Indo-Pacific Ocean decadal temperature and sea level variability over the period 1950-2007. The SODA data are evaluated against independent sea level anomalies from long-record tide gauges at Midway Island and Fremantle, reconstructed sea surface height anomalies, and sea surface height anomalies from TOPEX/Poseidon satellite altimeter observations at the decadal time scale. This study demonstrates that SODA captures the characteristic Interdecadal Pacific Oscillation (IPO) over the upper 200 m, and accurately represents these decadal changes against the independent observations. The SODA-product shows a meridional asymmetry of patterns that connect the western tropical Pacific and the Indian Ocean, apparently in relation to IPO changes. Regional sea level at the Midway Island and Fremantle tide gauges confirm this decadal connection and the relationship with the IPO. We concluded that SODA is potentially a useful tool to examine ocean decadal climate variability across the Indo-Pacific Ocean.

Vargas-Hernandez, J. Mauro; Wijffels, Susan; Meyers, Gary; Holbrook, Neil J.

2014-11-01

42

Nine decades of decreasing phenotypic variability in Atlantic cod.  

PubMed

Changes in phenotypic variability in natural populations have received little attention in comparison with changes in mean trait values. This is unfortunate because trait diversity may influence adaptive evolutionary change and population stability. We combine two unique data sets to illuminate complex trait changes in Atlantic cod along the Norwegian Skagerrak coast: (i) an annual beach seine survey starting in 1919, monitoring juvenile body size and abundance and (ii) capture-mark-recapture data from which we estimated selection on juvenile body size and growth. We demonstrate that the variability of juvenile size has been steadily decreasing across nine decades, with no evidence for a similar trend in mean size. We also report that small, slow-growing fish as well as large, fast-growing fish are selected against. Together, these results suggest long-term stabilizing selection acting on Atlantic cod, and emphasize the need for further studies evaluating the full complexity of trait changes in wild populations. PMID:19453620

Olsen, Esben Moland; Carlson, Stephanie M; Gjøsaeter, Jakob; Stenseth, Nils Chr

2009-07-01

43

Surface Salinity Variability in the North Atlantic During Recent Decades  

NASA Technical Reports Server (NTRS)

The sea surface salinity (SSS) variability in the North Atlantic is investigated using numerical model simulations for the last 50 years based on atmospheric forcing variability from Comprehensive Atmosphere Ocean Data Set (COADS) and National Center for Environmental Prediction / National Center for Atmospheric Research (NCEP/NCAR) Reanalysis. The largest interannual and longer term variability occurs in two regions: the Labrador Sea and the North Equatorial Countercurrent (NECC) region. In both regions the seasonality of the surface salinity variability is prominent with the maximum standard deviation occurring in the summer/fall period. In the Labrador Sea the summer SSS anomalies far exceed those of wintertime in amplitude. The interannual SSS variability in the subpolar gyre can be attributed to two factors: excess ice melt and heat flux (i.e. deep mixing) variations. On the other hand, heat flux variability can also lead to meridional overturning changes on decadal time scales such that weak overturning is manifested in fresh surface conditions in the subpolar gyre. The overturning changes also influence the NECC region SSS variability. Moreover, the subpolar freshening events are expected to occur during the negative phase of North Atlantic Oscillation which is associated with a weak wintertime surface heat loss in the subpolar gyre. No excess sea ice melt or precipitation is necessary for the formation of the fresh anomalies, because with the lack of wide-spread deep mixing, the fresh water that would be expected based on climatology, would accumulate at the surface. Thus, the fresh water 'conveyor' in the Atlantic operates via the overturning circulation such that deep mixing inserts fresh water while removing heat from the water column.

Haekkinen, Sirpa

2001-01-01

44

Principal modes of interannual and decadal variability of summer rainfall over South America  

Microsoft Academic Search

Using the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) product together with the Goddard Earth Observing System (GEOS) reanalysis and the National Center for Environmental Prediction (NCEP) sea-surface temperature (SST) data, we have conducted a diagnostic study of the interannual and decadal scale variability of principal modes of summer rainfall over South America for the period 1979-1995. By

Jiayu Zhou; K.-M. Lau

2001-01-01

45

Causes of Decadal Climate Variability over the North Pacific and North America  

Microsoft Academic Search

The cause of decadal climate variability over the North Pacific Ocean and North America is investigated by the analysis of data from a multidecadal integration with a state-of-the-art coupled ocean-atmosphere model and observations. About one-third of the low-frequency climate variability in the region of interest can be attributed to a cycle involving unstable air-sea interactions between the subtropical gyre circulation

M. Latif; T. P. Barnett

1994-01-01

46

Mechanisms of the Internally Generated Decadal-to-Multidecadal Variability in the Atlantic  

NASA Astrophysics Data System (ADS)

This study investigates the mechanisms of the internally generated decadal-to-multidecadal time scale SST variability in the Atlantic, including the North Atlantic Tripole variability, the Atlantic Multidecadal Variability and the Tropical Atlantic Variability, on the basis of a 300-year 1990 control simulation (CONTROL) made with CCSM3 and in an interactive ensemble version of CCSM3 (IE-CCSM3: 6 copies of AGCM coupled to the OGCM through the flux coupler). The structures, amplitudes and time scales of these three low frequency modes from CONTROL have properties similar to the observed variability, indicating that CCSM3 is appropriate for studying their mechanisms. These modes are closely related to the variability of the Atlantic Meridional Overturning Circulation (AMOC) on decadal time scales, suggesting that all of these types of variability may be manifestations of a single decadal "mode" of variability. To understand the low frequency modes and their interaction with each other, and the interaction among different oceanic regions, we isolate weather noise forcing from other mechanisms, including the coupled feedback, the gyre circulations, wave dynamics, and AMOC. The weather noise surface fluxes, including the net heat flux, wind stress and freshwater flux, are obtained from CONTROL by removing the SST forced surface fluxes, which are averaged from an ensemble of six AGCMs forced by the CONTROL SST. The IE-CCSM3 simulations in which the specified weather noise forcing is restricted to specific regions or in which the effects of the different specified surface fluxes are isolated are carried out to determine the contributions to the Atlantic decadal modes by region and by forcing type. Our results from the weather noise forced IE-CCSM3 simulations demonstrate that weather noise is responsible for most of decadal variability in the Atlantic and reveal the interactions between the three modes.

Chen, H.; Schneider, E. K.

2011-12-01

47

Evidence for multiple drivers of North Atlantic multi-decadal climate variability using CMIP5 models  

NASA Astrophysics Data System (ADS)

Observed North Atlantic Ocean surface temperatures have changed in a non-monotonic and non-uniform fashion over the last century. While future North Atlantic decadal-to-multi-decadal climate change will be driven by a combination of internal variability and anthropogenic as well as natural forcings, the relative importance of these effects is still unclear for the 20th century [Ting et al., 2009; Knight 2009; Ottera et al. 2010; DelSole et al., 2011; Booth et al. 2012]. Here we assess the relative roles of greenhouses gases, anthropogenic aerosols, natural forcings and internal variability to the North Atlantic surface temperature decadal fluctuations using CMIP5 multi-model historical simulations driven by estimates of observed external forcings. While the latter are the main source of decadal variability in the tropics and subtropics, there is a large contribution from the unforced component to subpolar Atlantic variations. Reconstruction of forced response patterns suggests that anthropogenic forcings are the main causes of the accelerated warming of the last three decades while internal variability has a dominant contribution to the early 20th-century temperature multi-decadal swings and recent abrupt changes in the subpolar Atlantic. Significant inter-model spread with regard to the spatial response patterns to anthropogenic forcing leads to substantial uncertainty as to robust attribution statements for the mid-to-late 20th century North Atlantic warm and cold periods. Comparing internal variability from preindustrial simulations with that estimated from the observed residual after removing the best estimate of the total forced response leads to a consistency metric which allows to identify models with a biased forced response.; CMIP5 multi-model ratio (?_LF) of the externally forced -natural and anthropogenic- variance, ?_EF to the total variance, ?_T, of fluctuations with a period greater than 10 years. Stippling indicates regions where the null hypothesis H0: ?_LF = 0 cannot be rejected at the 5% level using an F-test.

Terray, L.

2012-12-01

48

Decadal change in intraseasonal variability over the South China Sea  

NASA Astrophysics Data System (ADS)

Evidence is presented to reveal a decadal change around mid-1990s in the behavior of intraseasonal variability (ISV) over the South China Sea (SCS). During 1979-1993, the ISV has a spectral peak around 64 days, which is longer than in the recent epoch of 1994-2007 (around 42 days). The ISV event in 1979-1993 involves a merging process of the northward and westward propagating convection anomalies over the western North Pacific. The ISV in 1994-2007 has no such a merging process but exhibits a tilted band structure extending from the northern Indian Ocean to the SCS, which is strongly connected to the equatorial eastward propagating Madden-Julian Oscillation. The merging process during 1979-1993 modified the ISV over the SCS, resulting in the prolonged period, enhanced convective activity and a weakened relationship with the eastward propagating MJO. The possible cause of this change is discussed.

Kajikawa, Yoshiyuki; Yasunari, Tetsuzo; Wang, Bin

2009-03-01

49

Decadal variability in European wet and dry phases  

NASA Astrophysics Data System (ADS)

Climate varies over time and space, triggered by a large variety of processes. At continental and regional scales, numerous long-term changes in climate have been observed with profound direct and indirect influences on natural environments and the human society. This study focuses on the spatio-temporal characteristics and changes of long-lasting dry and wet spells in Europe for 1851-2010. Analysis is done for seven European sub-regions ranging from Northern Europa via Central Europe to the Mediterranean area. The decile indicator is used for precipitation time series to define long-lasting dry and wet phases that may last several months to years. Its calculation is based on three-month precipitation totals. Different decile-based thresholds are used to determine the start and the end of the respective dry or wet phase. They are calculated separately for each of the twelve three-month periods to account for the seasonal precipitation cycle. Links of this precipitation-based indicator to flood events in European catchments are examined. We noticed that during certain times, dry and wet phases, respectively, occur more frequent and last longer than during other times, where almost no event occurs. Considering all of Europe, dry phases were particularly frequent and long between 1880 and 1910, the mid-1940s to mid-1960s and in the mid 1970s, while wet phases showed a peak in occurrence from 1910 to the early 40s, from the mid-1960s to the early 1980s and from 1994 to 2010. The picture changes if individual sub-regions are considered. Opposite sub-regional trends lead to almost negligible or indifferent trends over Europe. Spatial extent and duration of dry phases have decreased noticeably and most pronounced in the second half of the 20th Century, while wet phases show increases in spatial extent and duration from 1851 to the present. Those developments are particularly pronounced in Northern Europe. Opposite trends - particularly for the second half of the 20th century - were noticed for Central Europe and the Mediterranean area. Besides those long-term trends exists a strong inter-decadal variability of the spatial coverage of dry and wet phases, respectively, within all sub-regions, indicating a relation of decile phase occurrence to long-term variations in atmospheric circulation. We explored the relationship between dry and wet phase occurrence and large-scale atmospheric circulation patterns, e.g., Hess-Brezowsky catalogue of circulation types (GWT), North Atlantic Oscillation (NAO) and Atlantic Multidecadal Oscillation (AMO) and found some links depending on the particular sub-region. Yet, the observed links cannot simply be reduced to simple cause-effect relationships.

Hänsel, Stephanie; Miketta, Wiebke; Matschullat, Jörg

2013-04-01

50

Evidence for Large Decadal Variability in the Tropical Mean Radiative Energy Budget  

NASA Technical Reports Server (NTRS)

It is widely assumed that variations in the radiative energy budget at large time and space scales are very small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. We demonstrate that the radiation budget changes are caused by changes In tropical mean cloudiness. The results of several current climate model simulations fall to predict this large observed variation In tropical energy budget. The missing variability in the models highlights the critical need to Improve cloud modeling in the tropics to support Improved prediction of tropical climate on Inter-annual and decadal time scales. We believe that these data are the first rigorous demonstration of decadal time scale changes In the Earth's tropical cloudiness, and that they represent a new and necessary test of climate models.

Wielicki, Bruce A.; Wong, Takmeng; Allan, Richard; Slingo, Anthony; Kiehl, Jeffrey T.; Soden, Brian J.; Gordon, C. T.; Miller, Alvin J.; Yang, Shi-Keng; Randall, David R.; Arnold, James E. (Technical Monitor)

2001-01-01

51

Decadal variability of the NAO: Introducing an augmented NAO index  

NASA Astrophysics Data System (ADS)

The wintertime NAO is traditionally defined as the first Empirical Orthogonal Function of monthly sea level pressure (SLP) anomalies for all winters and therefore remains fixed in space. The associated NAO index represents the projection of SLP onto the fixed NAO pattern. The NAO index is positive when the pressure contrast between the two centers of action is particularly strong; it is negative when the contrast is weak. This index represents an incomplete description of the wintertime NAO as the pattern is found to shift location on decadal timescales. This study investigates the movement of the centers of action (or nodes) of the NAO for winter in 20-yr running windows starting in 1871. A new climate index, the Angle index, is introduced. It is a measure of the asymmetry in location of the two nodes of the NAO defined in the partially overlapping 20-yr windows. The Angle index has a value of zero only when both nodes are located on the same meridian. It increases in positive value as the curve connecting the nodes tilts more to the northeast; it becomes negative when the tilt is to the northwest. The Angle index complements the smooth NAO index, which is the traditional NAO index averaged over the 20-yr window, especially when the Angle index is strongly negative as occurred during the Arctic warming of the early to mid 20th century. Regression analysis shows that the Angle index provides additional information about climate variability beyond that provided by the smooth NAO index.

Wang, Y.-H.; Magnusdottir, Gudrun; Stern, H.; Tian, X.; Yu, Y.

2012-11-01

52

Long-term climate change in the Mediterranean region in the midst of decadal variability  

NASA Astrophysics Data System (ADS)

Long-term climate change and decadal variability in the Mediterranean region during 1860-2100 are investigated based on observational data and the newly available Coupled Model Intercomparison Project—Phase 5 (CMIP5) experiments. Observational records show that decadal variability and a general tendency for annual-mean conditions to be warmer and drier have characterized the Mediterranean during 1860-2005. Consistency with CMIP5 model simulations including greenhouse gases (GHG), as well as anthropogenic aerosols and natural forcings, suggest that forced changes have characterized aspects of Mediterranean climate during this period. Future GHG-forced change will take place in the midst of decadal variability, both internal and forced, as it has occurred in the past. However, future rates of forced warming and drying over the Mediterranean are projected to be higher than in the past century. The degree to which forced change and internal variability will matter depends on the climatic quantity being considered. For surface air temperature and Mediterranean Sea annual-mean evaporation and surface freshwater fluxes, variability and forced change have become comparable and the forced signal has already emerged from internal variability. For quantities with large internal variability and relatively small forced signal such as precipitation, forced change will emerge later on in the twenty-first century over selected regions and seasons. Regardless, the probability distribution of future precipitation anomalies is progressively shifting towards drier conditions. Overall, results highlight that both mean projected forced change and the variability that will accompany forced mean change should be considered in the development of future climate outlooks.

Mariotti, Annarita; Pan, Yutong; Zeng, Ning; Alessandri, Andrea

2015-03-01

53

Long-term climate change in the Mediterranean region in the midst of decadal variability  

NASA Astrophysics Data System (ADS)

Long-term climate change and decadal variability in the Mediterranean region during 1860-2100 are investigated based on observational data and the newly available Coupled Model Intercomparison Project—Phase 5 (CMIP5) experiments. Observational records show that decadal variability and a general tendency for annual-mean conditions to be warmer and drier have characterized the Mediterranean during 1860-2005. Consistency with CMIP5 model simulations including greenhouse gases (GHG), as well as anthropogenic aerosols and natural forcings, suggest that forced changes have characterized aspects of Mediterranean climate during this period. Future GHG-forced change will take place in the midst of decadal variability, both internal and forced, as it has occurred in the past. However, future rates of forced warming and drying over the Mediterranean are projected to be higher than in the past century. The degree to which forced change and internal variability will matter depends on the climatic quantity being considered. For surface air temperature and Mediterranean Sea annual-mean evaporation and surface freshwater fluxes, variability and forced change have become comparable and the forced signal has already emerged from internal variability. For quantities with large internal variability and relatively small forced signal such as precipitation, forced change will emerge later on in the twenty-first century over selected regions and seasons. Regardless, the probability distribution of future precipitation anomalies is progressively shifting towards drier conditions. Overall, results highlight that both mean projected forced change and the variability that will accompany forced mean change should be considered in the development of future climate outlooks.

Mariotti, Annarita; Pan, Yutong; Zeng, Ning; Alessandri, Andrea

2015-01-01

54

Observing Variable Stars with Binoculars  

Microsoft Academic Search

In the past few years binoculars have become increasingly popular for astronomical observing. For over 30 years I have used hand-held binoculars for variable star work. The purpose of this discussion is to demonstrate that a viable program exists for variable star observing using binoculars.

Edward G. Oravec

1977-01-01

55

Decade of balloon observations of auroral X-rays  

SciTech Connect

The paper describes balloon observations of bremsstrahlung X-rays carried out by the University of Calgary over the past decade which deal with morphological studies of auroral electron precipitation. The program concentrated on the understanding of the correlation between parent electrons and secondary X-rays, the study of microbursts, east-west and north-south extent of electron precipitation, and precipitation during pulsating auroras.

Venkatesan, D.; Vij, K.K.

1981-01-01

56

Decadal Variability in Western North Atlantic SST Recorded in Massive Brain Corals from Bermuda  

Microsoft Academic Search

The history of the North Atlantic Oscillation (NAO) is characterized by variability on time scales of months to decades but low frequency (decadal and multidecadal) variability is especially marked since 1950, leading some to suggest a link to global warming. To address questions concerning the nature and mechanisms of low frequency NAO variability, we have initiated a program to reconstruct

A. L. Cohen; M. S. McCartney; S. R. Smith

2002-01-01

57

Evidence for large decadal variability in the tropical mean radiative energy budget.  

PubMed

It is widely assumed that variations in Earth's radiative energy budget at large time and space scales are small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. Results indicate that the radiation budget changes are caused by changes in tropical mean cloudiness. The results of several current climate model simulations fail to predict this large observed variation in tropical energy budget. The missing variability in the models highlights the critical need to improve cloud modeling in the tropics so that prediction of tropical climate on interannual and decadal time scales can be improved. PMID:11823638

Wielicki, Bruce A; Wong, Takmeng; Allan, Richard P; Slingo, Anthony; Kiehl, Jeffrey T; Soden, Brian J; Gordon, C T; Miller, Alvin J; Yang, Shi-Keng; Randall, David A; Robertson, Franklin; Susskind, Joel; Jacobowitz, Herbert

2002-02-01

58

Heat Recharge of the Equatorial Ocean: from ENSO to Decadal Climate Variability  

NASA Astrophysics Data System (ADS)

A key element of ENSO dynamics is heat recharge of the equatorial ocean that typically occurs prior to El Niño events. This recharge is evident in the observations and is included into conceptual models of ENSO, such as the recharge oscillator (Jin 1997, Meinen and McPhaden 2000). The focus of the present study is the phase lag between ocean heat recharge (measured as variations in upper ocean heat content along the equator) and variations in the Nino3 SST. First, from a theoretical perspective using the low-frequency approximation (Fedorov 2010), we derive a simple analytical expression for the phase lag that depends on the characteristic frequency of the oscillation, the meridional structure of wind stress anomalies, and oceanic damping. In a realistic parameter range, the phase lag given by the theory approaches 60° for an oscillation with a 4-year period, which on average agrees well with the observations. We next explore the dependence of this phase lag in CMIP5 models. We show that while some of those models do reproduce a reasonable phase lag in the interannual frequency band, many models simulate a lag significantly shorter or longer than observed (±60%). Further, the theory and observations predict a longer phase lag, ~90°, for decadal timescales. Only a few coupled models are able to capture this behavior, whereas other models produce a much shorter phase lag, and some produce a phase lag close to zero. These results suggest several types of dynamical behavior of tropical decadal variability in different models - from a dynamical mode similar to ENSO to purely damped mixed-layer variability. We conclude that differences in the simulated phase lag on timescales from interannual to decadal contribute to the broad diversity of simulated ENSO and decadal variability, as well as different prediction skills of the models.

Fedorov, A. V.; Muir, L.; Di Nezio, P. N.

2012-12-01

59

Contribution of natural decadal variability to global warming acceleration and hiatus  

NASA Astrophysics Data System (ADS)

Reasons for the apparent pause in the rise of global-mean surface air temperature (SAT) after the turn of the century has been a mystery, undermining confidence in climate projections. Recent climate model simulations indicate this warming hiatus originated from eastern equatorial Pacific cooling associated with strengthening of trade winds. Using a climate model that overrides tropical wind stress anomalies with observations for 1958-2012, we show that decadal-mean anomalies of global SAT referenced to the period 1961-1990 are changed by 0.11, 0.13 and -0.11 °C in the 1980s, 1990s and 2000s, respectively, without variation in human-induced radiative forcing. They account for about 47%, 38% and 27% of the respective temperature change. The dominant wind stress variability consistent with this warming/cooling represents the deceleration/acceleration of the Pacific trade winds, which can be robustly reproduced by atmospheric model simulations forced by observed sea surface temperature excluding anthropogenic warming components. Results indicate that inherent decadal climate variability contributes considerably to the observed global-mean SAT time series, but that its influence on decadal-mean SAT has gradually decreased relative to the rising anthropogenic warming signal.

Watanabe, Masahiro; Shiogama, Hideo; Tatebe, Hiroaki; Hayashi, Michiya; Ishii, Masayoshi; Kimoto, Masahide

2014-10-01

60

Impacts of Pacific Decadal Variability on Marine Ecosystems  

NASA Astrophysics Data System (ADS)

Over the past few decades a wealth of evidence has pointed to important connections between multi-decadal climate changes coherent with North Pacific ecosystem changes. The period from the late 1970's through the mid-1990's, for example, saw sustained high productivity for most Pacific salmon at the northern end of their range coinciding with sustained low productivity for Pacific salmon at the southern end of their range. It is now recognized that this "north-south inverse production pattern" for Pacific salmon played out over much of the 20th Century in response to Pacific climate changes: over multiple decades associated with the Pacific Decadal Oscillation, and from year-to-year associated with the El Nino Southern Oscillation. There is likewise abundant evidence for climate impacts on many other North Pacific marine species from the California Current north to the Bering Sea. In special cases, interdecadal ecosystem changes have been termed "regime shifts", wherein direct and indirect evidence points to large-scale ecosystem restructuring at both lower and upper trophic levels. The growing recognition of climate influences has undoubtedly aided our understanding of variations in Pacific marine ecosystems. In contrast, understanding and predicting ecosystem changes at the time-space scales important to fishery management decisions remains a major challenge.

Mantua, N. J.

2002-05-01

61

Interannual and decadal-scale variability of soil moisture and water resources in Africa  

NASA Astrophysics Data System (ADS)

Within water scarce regions such as the African continent, water availability is a fundamental factor for both ecosystems and human population. In particular the various ecoregions are highly vulnerable to climate change as seen in the recent drought in 2011, which affected the entire East African region and forced severe food crises causing the death of thousands of people. Several climate change scenarios associated with the expected population growth revealed an additional pressure on water availability, water accessibility and water demand in Africa in the future. In order to prevent, adapt and to mitigate climate change impacts (e.g. increasing water scarcity in the future) on soil moisture variability and water resources synthesis of its recent variations are extremely important. Unfortunately, there is currently no synthesis that highlights recent variations of soil moisture and fresh water resources in Africa. The aim of the study is to identify regions with large inter annual variability as well as decadal scale variability (trend, trend changes) of soil moisture and water resources. Hence, especially patterns of soil moisture and water resources variability will be demonstrated and implications in terms of vulnerability will be further discussed. The study comprises three different data sources: point measurements, remote sensing datasets and modelling results. Soil moisture observations from passive microwave radiometry (TRMM, AMSRE-E) and GRACE-derived terrestrial water storage were applied to locate areas which show a large inter annual variability. Supplementary, water level fluctuations from SAR altimetry (LEGOS/GOHS, ENVISAT) and in-situ runoff observations (SA FRIEND) provided by the Global Runoff Data Centre were used to confirm the encountered patterns of soil moisture and water resources variability. The spatial map of inter annual variability was subsequently overlaid by population density and land use data to assess the vulnerability of the African population to climate change. In order to put the findings of the synthesis in an historical perspective and to analyse the decadal scale variability and trends, runoff observations and modelled runoff from LPJML were also used.

Thomas, E.; Jung, M.; Wattenbach, M.; Heinke, J.; Weber, U.

2013-12-01

62

Variability of oceanic carbon cycle in the North Pacific from seasonal to decadal scales  

NASA Astrophysics Data System (ADS)

Variability of upper-ocean carbon cycle in the North Pacific during 1958-2010 period is investigated using a physical-biogeochemical model. Comparisons with in situ data from five different oceanographic environments in the South China Sea, Monterey Bay, North Pacific gyre, northwestern Pacific, and Gulf of Alaska indicate that the model usually captures observed seasonal and interannual variability in both sea surface pCO2 and sea-air CO2 flux. Seasonal variability of pCO2 and CO2 flux in the North Pacific follows the change in sea surface temperature (SST) closely with high and low values in summer and winter, respectively. Total CO2 modifies pCO2 seasonal pattern in an opposite manner with respect to SST, and surface wind speed modifies the magnitude of CO2 flux variations. On interannual and decadal time scales, sea surface pCO2 is primarily controlled by anthropogenic CO2, followed by modulations by the El Niño-Southern Oscillation and the Pacific Decadal Oscillation (PDO), while sea-air CO2 flux is significantly regulated by the PDO and the North Pacific Gyre Oscillation (NPGO). We show that anthropogenic CO2 tends to amplify the influence on CO2 flux from the PDO but to damp the influence from the NPGO.

Xiu, Peng; Chai, Fei

2014-08-01

63

Inter-Decadal to Multi-Decadal Sea Surface Temperature Variability in the Southwest Tropical Pacific Since AD 1648  

NASA Astrophysics Data System (ADS)

The southwest tropical Pacific is a region with temporally and spatially sparse sea surface temperature (SST) records that limit investigations of climate variability on interannual to centennial time scales for this region. We present a monthly resolved coral Sr/Ca record from 1648 to 1999 from Amédée Island, New Caledonia (22.48°S, 166.47°E), and reconstruct SST variability in the southwest Pacific for the past 350 years. The coral Sr/Ca record was assembled from two 3-m long coeval cores from the same massive Porites lutea coral colony. The chronology is based on annual density-band counting, cross- correlation of the two intracolony coral Sr/Ca records, and 11 230Th dates with 2? precision of ±1.1 to 16.5 years. The intracolony coral Sr/Ca variations are reproducible for more than three centuries (average monthly misfit error = ±0.015 mmol/mol; ~0.28°C), and the intracolony variations are coherent from interannual to centennial periodicities. The SST reconstructed from coral Sr/Ca shows a cooling trend from AD 1740 to 1815, a cold 19th century (~0.6°C with respect to AD 1967 to 1992), followed by a warming trend into the 20th century. Many of the cold events in the coral Sr/Ca record coincide with large volcanic eruptions (e.g., Tambora AD 1815 and Krakatau AD 1883). Spectral analysis reveals the record is dominated by modulating inter-decadal (14 to 21 years) periodicities and quasi-persistent multi-decadal (24 to 38 years) periodicities that do not exhibit coherence with the Pacific Decadal Oscillation (PDO) or the Inter-decadal Pacific Oscillation (IPO). Wavelet analysis reveals that the inter-decadal periodicities coincide with large volcanic eruptions, and the 55- to 70-year periodicities are coeval with volcanic cooling and warming trends in the 19th and 20th centuries. The multi-decadal periodicities may be a harmonic of the modulating inter-decadal periodicities or may represent an independent mode not previously recognized in the southwest Pacific.

Delong, K. L.; Quinn, T. M.; Taylor, F. W.; Lin, K.; Shen, C.

2008-12-01

64

Mechanisms for decadal scale variability in a simulated Atlantic meridional overturning circulation  

NASA Astrophysics Data System (ADS)

Variability in the Atlantic Meridional Overturning Circulation (AMOC) has been analysed using a 600-year pre-industrial control simulation with the Bergen Climate Model. The typical AMOC variability has amplitudes of 1 Sverdrup (1 Sv = 106 m3 s-1) and time scales of 40-70 years. The model is reproducing the observed dense water formation regions and has very realistic ocean transports and water mass distributions. The dense water produced in the Labrador Sea (1/3) and in the Nordic Seas, including the water entrained into the dense overflows across the Greenland-Scotland Ridge (GSR; 2/3), are the sources of North Atlantic Deep Water (NADW) forming the lower limb of the AMOC's northern overturning. The variability in the Labrador Sea and the Nordic Seas convection is driven by decadal scale air-sea fluxes in the convective region that can be related to opposite phases of the North Atlantic Oscillation. The Labrador Sea convection is directly linked to the variability in AMOC. Linkages between convection and water mass transformation in the Nordic Seas are more indirect. The Scandinavian Pattern, the third mode of atmospheric variability in the North Atlantic, is a driver of the ocean's poleward heat transport (PHT), the overall constraint on northern water mass transformation. Increased PHT is both associated with an increased water mass exchange across the GSR, and a stronger AMOC.

Medhaug, I.; Langehaug, H. R.; Eldevik, T.; Furevik, T.; Bentsen, M.

2012-07-01

65

Stellar Variability Observed with Kepler  

NASA Astrophysics Data System (ADS)

The Kepler photometer was launched in March 2009 initiating NASA's search for Earth-size planets orbiting in the habitable zone of their star. After three years of science operations, Kepler has proven to be a veritable cornucopia of science results, both for exoplanets and for astrophysics. The phenomenal photometric precision and continuous observations required in order to identify small, rocky transiting planets enables the study of a large range of phenomena contributing to stellar variability for many thousands of solar-like stars in Kepler's field of view in exquisite detail. These effects range from <1 ppm acoustic oscillations on timescales from a few minutes and longward, to flares on timescales of hours, to spot-induced modulation on timescales of days to weeks to activity cycles on timescales of months to years. Recent improvements to the science pipeline have greatly enhanced Kepler's ability to reject instrumental signatures while better preserving intrinsic stellar variability, opening up the timescales for study well beyond 10 days. We give an overview of the stellar variability we see across the full range of spectral types observed by Kepler, from the cool, small red M stars to the hot, large late A stars, both in terms of amplitude as well as timescale. We also present a picture of what the extended mission will likely bring to the field of stellar variability as we progress from a 3.5 year mission to a 7.5+ year mission.

Jenkins, Jon M.; Gilliland, Ronald L.; Meibom, Soeren; Walkowicz, Lucianne; Borucki, William J.; Caldwell, Douglas A. Caldwell

2015-03-01

66

Decadal variability of the Kuroshio Extension: mesoscale eddies and recirculations  

Microsoft Academic Search

An eddy-resolving multidecadal ocean model hindcast simulation is analyzed to investigate time-varying signals of the two\\u000a recirculation gyres present respectively to the north and south of the Kuroshio Extension (KE) jet. The northern recirculation\\u000a gyre (NRG), which has been detected at middepth recently by profiling float and moored current meter observations, is a major\\u000a focus of the present study. Low-frequency

Bunmei Taguchi; Bo Qiu; Masami Nonaka; Hideharu Sasaki; Shang-Ping Xie; Niklas Schneider

2010-01-01

67

Forced versus Intrinsic Variability of the Kuroshio Extension System on the Decadal Timescales  

NASA Astrophysics Data System (ADS)

A ubiquitous feature of the northern hemisphere subtropical ocean circulation is the the existence of an anticyclonic recirculation gyre (RG) on the southern flank of the wind-driven western boundary current outflow. The RGs significantly enhance the eastward volume and heat transport of the western boundary currents and their variability has been recognized in recent years to be crucial in understanding the decadal midlatitude oceanic changes. The dynamic cause for the decadal WBC variability, especially whether the observed varaibility is externally forced or reflects the intrinsic, nonlinear RG behavior, is still under debate. This cause in the Kuroshio Extension (KE) system is examined in this study by analyzing satellite altimeter sea surface height data, adopting simplified dynamic models, and evaluating nonlinear eddy-mean flow interaction. Long-term SSH measurements reveal clearly that the KE system oscillates between a stable and an unstable dynamic state. Transitions between the two states are caused by PDO-related, basin-scale wind stress curl forcing in the eastern North Pacific. During the positive PDO phase, wind-induced negative SSH anomalies from the east work to weaken the KE jet, shifting its path southward. The latter migration causes the KE jet to override the shallow Shtsky Rise, leading to an enhanced eddy kinetic energy (i.e, unstable) state of the KE. With a time lag of 1~2 yrs, the enhanced eddy variability is found to strengthen the KE's southern RG. Helped by the incoming, positive SSH anomalies from the east due to the negatively-phased PDO forcing, this eddy-driven circulation works to switch the KE system to a dynamically stable state. While the eddy-driven nonlinear RG dynamics facilitates modulations of the KE system, the decadal transitions of the KE system are found to be largely paced by the external PDO wind forcing. Specifically, we argue that the decadal timescale in the PDO wind forcing originates in the coupling of the KE SST variability and the basin-wide, midlatitude atmospheric responses (Qiu et al., 2007, J.Climate).

Qiu, B.; Chen, S.; Schneider, N.

2008-12-01

68

Principal modes of interannual and decadal variability of summer rainfall over South America  

NASA Astrophysics Data System (ADS)

Using the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) product together with the Goddard Earth Observing System (GEOS) reanalysis and the National Center for Environmental Prediction (NCEP) sea-surface temperature (SST) data, we have conducted a diagnostic study of the interannual and decadal scale variability of principal modes of summer rainfall over South America for the period 1979-1995. By filtering the annual and short (<12 months) time-scale variations, results of empirical orthogonal function analysis show three leading modes of rainfall variation identified with interannual, decadal and long-term variability. Together, these modes explain more than half the total variance of the filtered data.The first mode is highly correlated with El Niño-Southern Oscillation (ENSO), showing a regional rainfall anomaly pattern largely consistent with previous results. This mode captures the summer season interannual variability, not only the Northeast Brazil drought but also its connection with excessive rainfall over Southern Brazil and the Ecuador coast in El Niño years. Another distinctive feature is the strengthening of the low-level flow along the eastern foothills of the eastern Andes, signifying an enhancement of the South American summer monsoon in response to an El Niño anomaly.The decadal variation displays a meridional shift of the Inter-Tropical Convergence Zone (ITCZ), which is tied to the anomalous cross-equatorial SST gradient over the Atlantic and the eastern Pacific. Associated with this mode is a large-scale mass swing between polar regions and the mid-latitudes. Over the South Atlantic and the South Pacific, the anomalous subtropical high and the associated anomalous surface wind are dynamically consistent with the distribution of local SST anomalies, suggesting the importance of atmospheric forcing at the decadal time scale.The long-term variation shows that since 1980 there has been a decrease of rainfall from the northwest coast to the southeast subtropical region and a southwards shift of the Atlantic ITCZ, leading to increased rainfall over northern and eastern Brazil. Possible links of this mode to the observed SST warming trend over the subtropical South Atlantic and to the interdecadal SST variation over the extratropical North Atlantic are discussed.

Zhou, Jiayu; Lau, K.-M.

2001-11-01

69

Decadal variability in biogeochemical models: Comparison with a 50-year ocean colour dataset  

NASA Astrophysics Data System (ADS)

Assessing the skill of biogeochemical models to hindcast past variability is challenging, yet vital in order to assess their ability to predict biogeochemical change. However, the validation of decadal variability is limited by the sparsity of consistent, long-term biological datasets. The Phytoplankton Colour Index (PCI) product from the Continuous Plankton Recorder survey, which has been sampling the North Atlantic since 1948, is an example of such a dataset. Converting the PCI to chlorophyll values using SeaWiFS data allows a direct comparison with model output. Here we validate decadal variability in chlorophyll from the GFDL TOPAZ model. The model demonstrates skill at reproducing interannual variability, but cannot simulate the regime shifts evident in the PCI data. Comparison of the model output, data and climate indices highlights under-represented processes that it may be necessary to include in future biogeochemical models in order to accurately simulate decadal variability in ocean ecosystems.

Henson, Stephanie A.; Raitsos, Dionysios; Dunne, John P.; McQuatters-Gollop, Abigail

2009-11-01

70

Mesoscale disturbance and ecological response to decadal - scale climate variability in the American Southwest  

Microsoft Academic Search

ABSTRACT Ecological responses to climatic variability in the Southwest include regionally synchronized fires, insect outbreaks, and pulses in tree demography (births and deaths). Multicentury, tree-ring reconstructions of drought, disturbance history, and tree demography reveal climatic effects across scales, from annual to decadal, and from local (,10,). Climate?disturbance relations are more variable and complex than previously assumed. During the past three

Tw Swetnam; Jl Betancourt

1998-01-01

71

Surface salinity variability in the northern North Atlantic during recent decades  

E-print Network

Surface salinity variability in the northern North Atlantic during recent decades Sirpa Ha 2002; accepted 15 March 2002; published 18 September 2002. [1] The sea surface salinity (SSS surface salinity variability is prominent with the maximum standard deviation (SD) occurring in the summer

72

Holocene Multi-Decadal to Millennial-Scale Hydrologic Variability on the South American Altiplano  

NASA Astrophysics Data System (ADS)

On orbital timescales, lacustrine sediment records in the tropical central Andes show massive changes in lake level due to mechanisms related to global-scale drivers, varying at precessional timescales. Here we use stable isotopic and diatom records from two lakes in the Lake Titicaca drainage basin to reconstruct multi- decadal to millennial scale precipitation variability during the last 7000 to 8000 years. The records are tightly coupled at multi-decadal to millennial scales with each other and with lake-level fluctuations in Lake Titicaca, indicating that the lakes are recording a regional climate signal. A quantitative reconstruction of precipitation from stable isotopic data indicates that the central Andes underwent significant wet to dry alternations at multi- centennial frequencies with an amplitude of 30 to 40% of total precipitation. A strong millennial-scale component, similar in duration to periods of increased ice rafted debris flux in the North Atlantic, is observed in both lake records, suggesting that tropical North Atlantic sea-surface temperature (SST) variability may partly control regional precipitation. No clear relationship is evident between these records and the inferred ENSO history from Lago Pallcacocha in the northern tropical Andes. In the instrumental period, regional precipitation variability on inter-annual timescales is clearly influenced by Pacific modes; for example, most El Ninos produce dry and warm conditions in this part of the central Andes. However, on longer timescales, the control of tropical Pacific modes is less clear. Our reconstructions suggest that the cold intervals of the Holocene Bond events are periods of increased precipitation in the central Andes, thus indicating an anti-phasing of precipitation variation in the southern tropics of South America relative to the Northern Hemisphere monsoon region.

Fritz, S. C.; Baker, P. A.; Ekdahl, E.; Burns, S.

2006-12-01

73

Multi-decadal variability of the eastern North Atlantic subpolar gyre  

NASA Astrophysics Data System (ADS)

The Extended Ellett Line is a hydrographic section sampling the eastern North Atlantic subpolar gyre from Iceland to Scotland. The section samples the main warm-water path of the Atlantic meridional overturning circulation (AMOC) from the subtropics to the Nordic Seas and the cold-water return flow from the Faroe Bank Channel south of Iceland. Here we present property and circulation variability from 18 annual hydrographic sections since 1996. Uncertainties due to aliasing are examined using float-based products, model output and altimetry. Nearest to Scotland in the Rockall Trough we have 65-years of data showing multi-decadal variability of upper ocean heat and salt anomalies feeding into the Nordic Seas. The amplitude of temperature and salinity changes are 0.5°C and 0.08 (salinity), with highs in the mid-2000s. The anomalies are influenced by the strength of the circulation of the subpolar gyre and indicate large-scale changes. The causes of the observed variability of properties and circulation, the relationships between the basins, and the influence of the AMOC and atmosphere are discussed.

Cunningham, Stuart; Holliday, N. Penny; Johnson, Clare; Gary, Stefan

2014-05-01

74

Decadal-scale Climate Variability in the Gulf of Mexico During the Past 3000 Years  

Microsoft Academic Search

Understanding 20th century global warming depends in part on documenting natural climate variability beyond the range of instrumental records. However, proxy records of decadal-scale climate variability during the past 3000 years are sparse, especially for low-latitude oceans. Generation of proxy climate records from high accumulation rate sediment cores from the Gulf of Mexico can help evaluate climate variability in the

B. P. Flower; T. M. Quinn

2007-01-01

75

Decadal Air-Sea Interaction in the North Atlantic Based on Observations and Modeling Results  

NASA Technical Reports Server (NTRS)

The decadal, 12-14 year, cycle observed in the North Atlantic SST and tide gauge data was examined using the NCEP/NCAR reanalyses, COADS data and an ocean model simulation. Besides this decadal mode, a shorter, subdecadal period of about 8 years exists in tide gauge data north of 40N, in the subpolar SST and in the winter North Atlantic Oscillation (NAO) index and in subpolar winter heat flux values. The decadal cycle is a well separated mode in a singular spectrum analysis (SSA) for a time series of SST EOF mode 1 with a center over the Gulf Stream extension. Tide gauge and SST data are consistent in that both show a significant subdecadal periodicity exclusively in the subpolar gyre, but in subtropics the 12-14 year period is the prominent, but nonstationary, decadal signal. The main finding of this study is that this 12-14 year cycle can be constructed based on the leading mode of the surface heat flux. This connection to the surface heat flux implicates the participation of the thermohaline circulation in the decadal cycle. During the cycle starting from the positive index phase of NAO, SST and oceanic heat content anomalies are created in subtropics due to local heat flux and intensification of the thermohaline circulation. The anomalies advect to the subpolar gyre where they are amplified by local heat flux and are part of the negative feedback of thermohaline circulation on itself. Consequently the oceanic thermohaline circulation slows down and the opposite cycle starts. The oscillatory nature would not be possible without the active atmospheric participation in the cycle, because it provides the unstable interaction through heat flux, without it, the oceanic mode would be damped. This analysis suggests that the two principal modes of heat flux variability, corresponding to patterns similar to North Atlantic Oscillation (NAO) and Western Atlantic (WA), are part of the same decadal cycle and an indirect measure of the north-south movement of the storm tracks.

Hakkinen, Sirpa

1998-01-01

76

Observations of Interesting Cataclysmic Variables  

NASA Astrophysics Data System (ADS)

Cataclysmic Variables (CVs) comprise one category of active mass transfer binaries containing a white dwarf accreting from an orbiting late main-sequence companion. Undoubtedly, non-magnetic CVs, intermediate polars and polars constitute a powerful probe of the structure of accretion onto white dwarfs and the theories of angular momentum loss, which elucidate the long-term evolution leading to the formation of these short period compact binaries. Combining photometric and spectroscopic data from space and ground telescopes can lead to novel discoveries. The SDSS survey provided a large dataset of spectra of different types of CVs. Followup photometry and spectroscopy is still underway to determine the unique properties of the objects identified as CVs. The Kepler program provided the first look at the variability of CVs over a continuous timescale of months. The extension of the program to the K2 fields allows further sets of CVs to be explored. We present some interesting results for several new CVs found in the SDSS and Kepler surveys which include their behavior during quiescence and outburst. These observations further demonstrate the complexities of CVs. This research was partially funded by CAS visiting scholar grant, NSF grant AST-1008734 and NASA grant HST-GO12870.

Dai, Zhibin; Szkody, Paula; Garnavich, Peter M.; Kennedy, Mark

2015-01-01

77

Arctic forcing of decadal variability in the tropical Pacific Ocean in a high-resolution global coupled GCM  

NASA Astrophysics Data System (ADS)

The hypothesis that northern high-latitude atmospheric variability influences decadal variability in the tropical Pacific Ocean by modulating the wind jet blowing over the Gulf of Tehuantepec (GT) is examined using the high-resolution configuration of the MIROC 3.2 global coupled model. The model is shown to have acceptable skill in replicating the spatial pattern, strength, seasonality, and time scale of observed GT wind events. The decadal variability of the simulated GT winds in a 100-year control integration is driven by the Arctic Oscillation (AO). The regional impacts of the GT winds include strong sea surface cooling, increased salinity, and the generation of westward-propagating anticyclonic eddies, also consistent with observations. However, significant nonlocal effects also emerge in concert with the low-frequency variability of the GT winds, including anomalously low upper ocean heat content (OHC) in the central tropical Pacific Ocean. It is suggested that the mesoscale eddies generated by the wind stress curl signature of the GT winds, which propagate several thousand kilometers toward the central Pacific, contribute to this anomaly by strengthening the meridional overturning associated with the northern subtropical cell. A parallel mechanism for the decadal OHC variability is considered by examining the Ekman and Sverdrup transports inferred from the atmospheric circulation anomalies in the northern midlatitude Pacific directly associated with the AO.

Karnauskas, Kristopher B.

2014-06-01

78

HERSCHEL OBSERVATIONS OF CATACLYSMIC VARIABLES  

SciTech Connect

We have used the PACS instrument on the Herschel Space Observatory to observe eight cataclysmic variables at 70 and 160 {mu}m. Of these eight objects, only AM Her was detected. We have combined the Herschel results with ground-based, Spitzer, and WISE observations to construct spectral energy distributions for all of the targets. For the two dwarf novae in the sample, SS Cyg and U Gem, we find that their infrared luminosities are completely dominated by their secondary stars. For the two highly magnetic 'polars' in our survey, AM Her and EF Eri, we find that their mid-infrared excesses, previously attributed to circumbinary dust emission, can be fully explained by cyclotron emission. The WISE light curves for both sources show large, orbitally modulated variations that are identically phased to their near-IR light curves. We propose that significant emission from the lowest cyclotron harmonics (n {<=} 3) is present in EF Eri and AM Her. Previously, such emission would have been presumed to be optically thick, and not provide significant orbitally modulated flux. This suggests that the accretion onto polars is more complicated than assumed in the simple models developed for these two sources. We develop a model for the near-/mid-IR light curves for WZ Sge with an L2 donor star that shows that the ellipsoidal variations from its secondary star are detected. We conclude that none of the targets surveyed have dusty circumbinary disks.

Harrison, Thomas E.; Hamilton, Ryan T. [Department of Astronomy, New Mexico State University, Box 30001, MSC 4500, Las Cruces, NM 88003-8001 (United States); Tappert, Claus [Departamento de Fisica y Astronomia, Universidad de Valparaiso, Avda. Gran Bretana 1111, Valparaiso (Chile); Hoffman, Douglas I. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Campbell, Ryan K., E-mail: tharriso@nmsu.edu, E-mail: rthamilt@nmsu.edu, E-mail: claus.tappert@uv.cl, E-mail: dhoffman@ipac.caltech.edu, E-mail: Ryan.Campbell@humobldt.edu [Department of Physics and Astronomy, Humboldt State University, 1 Harpst St., Arcata, CA 95521 (United States)

2013-01-01

79

Response of Tropical Forests to Intense Climate Variability and Rainfall Anomaly over the Last Decade  

NASA Astrophysics Data System (ADS)

During the last decade, strong precipitation anomalies resulted from increased sea surface temperature in the tropical Atlantic, have caused extensive drying trends in rainforests of western Amazonia, exerting water stress, tree mortality, biomass loss, and large-scale fire disturbance. In contrast, there have been no reports on large-scale disturbance in rainforests of west and central Africa, though being exposed to similar intensity of climate variability. Using data from Tropical Rainfall Mapping Mission (TRMM) (1999-2010), and time series of rainfall observations from meteorological stations (1971-2000), we show that both Amazonian and African rainforest experienced strong precipitation anomalies from 2005-2010. We monitored the response of forest to the climate variability by analyzing the canopy water content observed by SeaWinds Ku-band Scatterometer (QSCAT) (1999-2009) and found that more than 70 million ha of forests in western Amazonia experienced a strong water deficit during the dry season of 2005 and a closely corresponding decline in canopy backscatter that persisted until the next major drought in 2010. This decline in backscatter has been attributed to loss of canopy water content and large-scale tree mortality corroborated by ground and airborne observations. However, no strong impacts was observed on tropical forests of Africa, suggesting that the African rainforest may have more resilience to droughts. We tested this hypothesis by examining the seasonal rainfall patterns, maximum water deficit, and the surface temperature variations. Results show that there is a complex pattern of low annual rainfall, moderate seasonality, and lower surface temperature in Central Africa compared to Amazonia, indicating potentially a lower evapotranspiration circumventing strong water deficits

Saatchi, S.; Asefi, S.

2012-04-01

80

The GEOS Association of Variable Star Observers  

NASA Astrophysics Data System (ADS)

(Abstract only) Groupe Européen d'Observation Stellaire (GEOS) is an astronomical association created in the 1970s to promote research among amateurs in Europe. We started in Belgium, France, and Italy, later extended to Spain, Switzerland, and Germany, and more recently, added U.S. amateurs. The basic idea was that amateurs should themselves extract scientific information from their observations (visually at first and later electronically) and publish their results. Some GEOS members have become professional astronomers and the amateur-professional collaboration has strengthened over the years. From the beginning, it has been clear that the study of variable stars is a privileged topic where such projects can develop. Since the 1980s GEOS members have published a number of scientific papers, even in refereed professional journals. Presently, observations are mainly done using CCD cameras though visual measurements still exist. In the past decade our main development has been the creation of a public RR Lyr star maxima database. This is a unique tool for the study of RR Lyr stars, as it enables the user to follow period variations since a star's discovery, some over 100 years ago. In parallel to the database, a project called "GEOS RR Lyr survey" was designed. Its aims include: first, add significantly more maxima timings of the brightest RR Lyr stars essentially using robotic telescopes; second, study fainter understudied stars to refine their period and find new stars which exhibit the so-called Blazhko effect; third, characterize the Blazhko effect, one of our main research topics. Other variable stars are also studied: eclipsing binaries, d Scuti stars, and so on. GEOS has a good cooperation with other variable star associations, mainly BAV and AAVSO.

Hambsch, F.-J.; LeBorgne, J.-F.; Poretti, E.; GEOS association

2012-06-01

81

Seasonal to multi-decadal variability of the width of the tropical belt  

NASA Astrophysics Data System (ADS)

An expansion of the tropical belt has been extensively reported in observations, reanalyses, and climate model simulations, but there is a great deal of uncertainty in estimates of the rate of widening as different diagnostics give a wide range of results. This study critically examines robust diagnostics for the width of the tropical belt to explore their seasonality, interannual variability, and multi-decadal trends. These diagnostics are motivated by an exploration of two simple models of the Hadley circulation and subtropical jets. The width based on the latitudes of the maximum tropospheric dry bulk static stability, measuring the difference in potential temperature between the tropopause and the surface, is found to be closely coupled to the width based on the subtropical jet cores on all timescales. In contrast, the tropical belt width and Northern Hemisphere edge latitudes based on the latitudes at which the vertically-averaged streamfunction vanishes, a measure of the Hadley circulation's poleward edges, lags those of the other diagnostics by approximately one month. The tropical belt width varies by up to ten degrees latitude among the diagnostics, with trends in the tropical belt width ranging from -0.5 to 2.0 degrees per decade over the 1979-2012 period. Nevertheless, in agreement with previous studies nearly all diagnostics exhibit a widening trend, although the streamfunction diagnostic exhibits a significantly stronger widening than either the jet or dry bulk stability diagnostics. Finally, GPS radio occultation observations are used to assess the ability of the reanalyses to reproduce the tropical belt width, finding that they better situate the latitudes of maximum bulk stability versus those of the subtropical jets.

Davis, Nicholas Alexander

82

Associations of decadal to multidecadal sea-surface temperature variability with Upper Colorado River flow  

USGS Publications Warehouse

The relations of decadal to multidecadal (D2M) variability in global sea-surface temperatures (SSTs) with D2M variability in the flow of the Upper Colorado River Basin (UCRB) are examined for the years 1906-2003. Results indicate that D2M variability of SSTs in the North Atlantic, North Pacific, tropical Pacific, and Indian Oceans is associated with D2M variability of the UCRB. A principal components analysis (with varimax rotation) of detrended and 11-year smoothed global SSTs indicates that the two leading rotated principal components (RPCs) explain 56% of the variability in the transformed SST data. The first RPC (RPC1) strongly reflects variability associated with the Atlantic Multidecadal Oscillation and the second RPC (RPC2) represents variability of the Pacific Decadal Oscillation, the tropical Pacific Ocean, and Indian Ocean SSTs. Results indicate that SSTs in the North Atlantic Ocean (RPC1) explain as much of the D2M variability in global SSTs as does the combination of Indian and Pacific Ocean variability (RPC2). These results suggest that SSTs in all of the oceans have some relation with flow of the UCRB, but the North Atlantic may have the strongest and most consistent association on D2M time scales. Hydroclimatic persistence on these time scales introduces significant nonstationarity in mean annual streamflow, with critical implications for UCRB water resource management. ?? 2007 American Water Resources Association.

McCabe, G.J.; Betancourt, J.L.; Hidalgo, H.G.

2007-01-01

83

Mesoscale Disturbance and Ecological Response to Decadal Climatic Variability in the American Southwest  

Microsoft Academic Search

Ecological responses to climatic variability in the Southwest include regionally synchronized fires, insect outbreaks, and pulses in tree demography (births and deaths). Multicentury, tree-ring reconstructions of drought, disturbance history, and tree demography reveal climatic effects across scales, from annual to decadal, and from local (,102 km2) to mesoscale (10 4-106 km2). Climate-disturbance relations are more variable and complex than previously

Thomas W. Swetnam; Julio L. Betancourt

1998-01-01

84

Optimal nonlinear excitation of decadal variability of the North Atlantic thermohaline circulation  

NASA Astrophysics Data System (ADS)

Nonlinear development of salinity perturbations in the Atlantic thermohaline circulation (THC) is investigated with a three-dimensional ocean circulation model, using the conditional nonlinear optimal perturbation method. The results show two types of optimal initial perturbations of sea surface salinity, one associated with freshwater and the other with salinity. Both types of perturbations excite decadal variability of the THC. Under the same amplitude of initial perturbation, the decadal variation induced by the freshwater perturbation is much stronger than that by the salinity perturbation, suggesting that the THC is more sensitive to freshwater than salinity perturbation. As the amplitude of initial perturbation increases, the decadal variations become stronger for both perturbations. For salinity perturbations, recovery time of the THC to return to steady state gradually saturates with increasing amplitude, whereas this recovery time increases remarkably for freshwater perturbations. A nonlinear (advective) feedback between density and velocity anomalies is proposed to explain these characteristics of decadal variability excitation. The results are consistent with previous ones from simple box models, and highlight the importance of nonlinear feedback in decadal THC variability.

Zu, Ziqing; Mu, Mu; Dijkstra, Henk A.

2013-11-01

85

Decadal and long-term sea level variability in the tropical Indo-Pacific Ocean  

NASA Astrophysics Data System (ADS)

In this study, we analysed decadal and long-term steric sea level variations over 1966-2007 period in the Indo-Pacific sector, using an ocean general circulation model forced by reanalysis winds. The simulated steric sea level compares favourably with sea level from satellite altimetry and tide gauges at interannual and decadal timescales. The amplitude of decadal sea level variability (up to ~5 cm standard deviation) is typically nearly half of the interannual variations (up to ~10 cm) and two to three times larger than long-term sea level variations (up to 2 cm). Zonal wind stress varies at decadal timescales in the western Pacific and in the southern Indian Ocean, with coherent signals in ERA-40 (from which the model forcing is derived), NCEP, twentieth century and WASWind products. Contrary to the variability at interannual timescale, for which there is a tendency of El Niño and Indian Ocean Dipole events to co-occur, decadal wind stress variations are relatively independent in the two basins. In the Pacific, those wind stress variations drive Ekman pumping on either side of the equator, and induce low frequency sea level variations in the western Pacific through planetary wave propagation. The equatorial signal from the western Pacific travels southward to the west Australian coast through equatorial and coastal wave guides. In the Indian Ocean, decadal zonal wind stress variations induce sea level fluctuations in the eastern equatorial Indian Ocean and the Bay of Bengal, through equatorial and coastal wave-guides. Wind stress curl in the southern Indian Ocean drives decadal variability in the south-western Indian Ocean through planetary waves. Decadal sea level variations in the south-western Indian Ocean, in the eastern equatorial Indian Ocean and in the Bay of Bengal are weakly correlated to variability in the Pacific Ocean. Even though the wind variability is coherent among various wind products at decadal timescales, they show a large contrast in long-term wind stress changes, suggesting that long-term sea level changes from forced ocean models need to be interpreted with caution.

Nidheesh, A. G.; Lengaigne, Matthieu; Vialard, Jérôme; Unnikrishnan, A. S.; Dayan, H.

2013-07-01

86

Decadal changes in the South Pacific western boundary current system revealed in observations and ocean state estimates  

NASA Astrophysics Data System (ADS)

Observations and ocean state estimates are used to investigate the nature and mechanism of decadal variability in the East Australian Current (EAC) system and South Pacific subtropical gyre. A 62 year record on the Tasmanian continental shelf shows decadal variations of temperature and salinity, as well as a long-term trend, which has been related to wind-driven variations in the poleward extension of the EAC. Repeat expendable bathythermograph lines spanning the last 15 years suggest that low-frequency variations in the transport of the EAC extension and Tasman Front are anticorrelated, but the time series are too short to draw firm conclusions. Here we use two ocean state estimates spanning the past 50 years to diagnose the physical mechanisms and spatial structure of the decadal variability of the South Pacific subtropical gyre. The observations and state estimates paint a consistent picture of the decadal variability of the gyre and EAC system. Strengthening of the basin-wide wind stress curl drives a southward expansion of the subtropical gyre. As the gyre shifts south, the EAC extension pathway is favored at the expense of the Tasman Front, resulting in the observed anticorrelation of the these two major currents. The results suggest that the subtropical gyre and western boundary current respond to decadal variability in basin-scale wind stress curl, consistent with Island Rule dynamics; that strong decadal variability of the South Pacific gyre complicates efforts to infer trends from short-term records; and that wind stress curl changes over the South Pacific basin drive changes in the EAC system that are likely to have implications for marine ecosystems and regional climate.

Hill, K. L.; Rintoul, S. R.; Ridgway, K. R.; Oke, P. R.

2011-01-01

87

Beaufort Gyre freshwater reservoir: State and variability from observations  

Microsoft Academic Search

We investigate basin-scale mechanisms regulating anomalies in freshwater content (FWC) in the Beaufort Gyre (BG) of the Arctic Ocean using historical observations and data collected in 2003–2007. Specifically, the mean annual cycle and interannual and decadal FWC variability are explored. The major cause of the large FWC in the BG is the process of Ekman pumping (EP) due to the

Andrey Proshutinsky; Richard Krishfield; Mary-Louise Timmermans; John Toole; Eddy Carmack; Fiona McLaughlin; William J. Williams; Sarah Zimmermann; Motoyo Itoh; Koji Shimada

2009-01-01

88

Variable stars across the observational HR diagram  

Microsoft Academic Search

An overview of pulsating variable stars across the observational Hertzprung-Russel (HR) diagram is presented, together with a summary of their global properties. The HR diagram is presented with a third colour-coded dimension, visualizing the fraction of variable, the amplitude of variability or the period of variability. The distribution of variable stars in the other observational diagrams, such as the Period-Amplitude

Laurent Eyer; Nami Mowlavi

2008-01-01

89

Evidence for Large Decadal Variability in the Tropical Mean Radiative Energy Budget  

Microsoft Academic Search

It is widely assumed that variations in Earth's radiative energy budget at large time and space scales are small. We present new evidence from a compilation of over two decades of accurate satellite data that the top-of-atmosphere (TOA) tropical radiative energy budget is much more dynamic and variable than previously thought. Results indicate that the radiation budget changes are caused

Bruce A. Wielicki; Takmeng Wong; Richard P. Allan; Anthony Slingo; Jeffrey T. Kiehl; Brian J. Soden; C. T. Gordon; Alvin J. Miller; Shi-Keng Yang; Franklin Robertson; Joel Susskind; Herbert Jacobowitz

2002-01-01

90

North Atlantic decadal variability and the formation of tropical storms and hurricanes  

E-print Network

North Atlantic decadal variability and the formation of tropical storms and hurricanes Robert L of 23.5°N and of Atlantic major hurricanes increased between the 1970's/1980's and 1995 implying that tropical storm, and most likely major hurricane, activity may be reduced in the next several

91

Diagnosing the causes of decadal-scale precipitation variability in northeastern sub-Saharan Africa  

NASA Astrophysics Data System (ADS)

The northeastern part of sub-Saharan Africa receives maximum rainfall during summer (June-September), as precipitation tracks the migration of the inter-tropical convergence zone (ITCZ) throughout tropical eastern Africa. Importantly, Ethiopia, Sudan, Eritrea, and northern Uganda experienced substantial precipitation declines during the past 50-60 years. These declines have not been spatially uniform. In the southern portion of this region, the decline has been steady and is ongoing with ~15-20% less summer rainfall in recent years than in the 1950s and 1960s. In the northwest, rainfall is much more variable inter-annually and a partial recovery has occurred after declines of ~30% from 1950-1985. In the northeast, declines from 1950-1985 were less extreme and have since completely recovered. What is the reasoning behind the rainfall declines in these regions, and why have they reversed in the north but continued in the south? I use a variety of observational, reanalysis, and modeled climate data to address these questions. The ongoing intensification of drought in the south is mainly attributable to declining moisture transports from the tropical Indian Ocean as a result of increasing subsidence over the eastern Horn of Africa. The increasing subsidence appears to be associated with warming of the tropical warm pool and increasing convection above the warm pool. In northern Sudan and Ethiopia, the drought from 1950-1985 and subsequent recovery appear to be associated with decadal-scale variability in the position and intensity of the ITCZ. This variability may be due to variations in the contrasting temperatures of the northern and southern hemisphere. I will refer to modeled and reconstructed past climate data to address whether increasing global temperatures have impacted these large-scale climate processes impacting summer rainfall in northeastern sub-Saharan Africa.

Williams, P.

2010-12-01

92

Top-of-atmosphere radiative contribution to unforced decadal global temperature variability in climate models  

NASA Astrophysics Data System (ADS)

Much recent work has focused on unforced global mean surface air temperature (T) variability associated with the efficiency of heat transport into the deep ocean. Here the relationship between unforced variability in T and the Earth's top-of-atmosphere (TOA) energy balance is explored in preindustrial control runs of the Coupled Model Intercomparison Project Phase 5 multimodel ensemble. It is found that large decadal scale variations in T tend to be significantly enhanced by the net energy flux at the TOA. This indicates that unforced decadal variability in T is not only caused by a redistribution of heat within the climate system but can also be associated with unforced changes in the total amount of heat in the climate system. It is found that the net TOA radiation imbalances result mostly from changes in albedo associated with the Interdecadal Pacific Oscillation that temporarily counteracts the climate system's outgoing longwave (i.e., Stefan-Boltzmann) response to T change.

Brown, Patrick T.; Li, Wenhong; Li, Laifang; Ming, Yi

2014-07-01

93

EarthScope's USArray: A Decade of Observations and Results  

NASA Astrophysics Data System (ADS)

EarthScope's USArray observatory provides unprecedented observations of geophysical targets across the contiguous United States through the systematic deployment of seismic, magnetotelluric, and atmospheric instruments. In addition, USArray includes tightly integrated data management and outreach activities. The seismic and atmospheric components of USArray consist of a Transportable Array (TA), Flexible Array (FA), and Reference Network. The TA has now occupied approximately 1700 sites spanning the entire contiguous 48 states, at 70 km inter-station spacing. These stations have provided broadband seismic, barometric pressure and atmospheric infrasound observations. The pool of instruments that comprise the FA have been deployed by numerous individual investigators in dense arrays to investigate local and regional features over time periods ranging from days to years. The Reference Network provides a permanent, stationary foundation for the TA and FA, with approximately 100 broadband stations deployed across the contiguous US at roughly 300 km spacing. The magnetotelluric (MT) component of USArray has provided both fixed and campaign-style long-period magnetotelluric observations at hundreds of locations across the US. Many of the field activities of USArray engaged both students and the public in important ways and this has been a significant component of USArray outreach. The TA alone has engaged well over one hundred students in site reconnaissance activities and placed seismic stations on the property of roughly a thousand different landowners. All data collected by USArray are openly available, most in real time. Many of the observations have also been incorporated into a variety of data products that have been developed to facilitate use of USArray by many different audiences. The scientific community has used USArray data to achieve a wide range of results--some that were anticipated when the facility was proposed and some that were completely unanticipated. Data products such as direct visualizations of seismic wave propagation observed by the TA have been viewed hundreds of thousands of times on the web by the general public. We will provide a brief overview of the deployments and accomplishments of USArray from the past ten years, and an overview of the significant and diverse scientific results that have been achieved. We will touch on some of the technologies and organizational and operational strategies that have enabled the success of USArray. We will conclude with a brief discussion of USArray plans for the next five years.

Woodward, R.; Busby, R. W.; Hafner, K.; Gridley, J. M.; Schultz, A.; Frassetto, A.; Simpson, D. W.

2013-12-01

94

Decadal variability and trends of the Benguela Upwelling System as simulated in a high-resolution ocean simulation  

NASA Astrophysics Data System (ADS)

Detecting the atmospheric drivers of the Benguela Upwelling Systems is essential to understand its present variability and its past and future changes. We present a statistical analysis of an ocean-only simulation driven by observed atmospheric fields over the last decades with the aim of identifying the large-scale atmospheric drivers of upwelling variability and trends. The simulation is found to reproduce well the seasonal cycle of upwelling intensity, with a maximum in the June-to-August season in North Benguela and in the December-to-February season in South Benguela. The statistical analysis of the interannual variability of upwelling focuses on its relationship to atmospheric variables (sea level pressure, 10 m-wind, wind stress). The relationship between upwelling and the atmospheric variables differ somewhat in the two regions, but generally, the correlation patterns reflect the common atmospheric pattern favoring upwelling: southerly wind/wind stress, strong subtropical anticyclone, and an ocean-land sea level pressure gradient. In addition, the statistical link between upwelling and large-scale climate variability modes was analyzed. The El Niño Southern Oscillation and the Antarctic Oscillation exert some influence on austral summer upwelling velocities in South Benguela. The decadal evolution and the long-term trends of upwelling and of ocean-minus-land air pressure gradient do not agree with Bakun's hypothesis that anthropogenic climate change should generally intensify coastal upwelling.

Tim, N.; Zorita, E.; Hünicke, B.

2015-03-01

95

Mechanisms for decadal scale variability in the North Atlantic Ocean circulation in the Bergen Climate Model  

NASA Astrophysics Data System (ADS)

Potential mechanisms for decadal scale variability for the Atlantic Meridional Overturning Circulation (AMOC) and Subpolar Gyre strength have been identified from a 600-year pre-industrial control simulation with the Bergen Climate Model. In short, the variability appears rooted in the atmosphere. The three dominant modes of North Atlantic atmospheric variability - the North Atlantic Oscillation (NAO), the East Atlantic Pattern (EAP) and the Scandinavian Pattern (SP), are all reflected in the ocean circulation. The variable heat flux related to NAO drives convective mixing in the Labrador Sea and thus the formations of upper North Atlantic Deep Water. Negative phases of SP are associated with northerly winds and consequently increased water mass exchange across the Greenland-Scotland Ridge, including more overflow of lower North Atlantic Deep Water and more poleward heat transport with the Atlantic inflow. Finally, the variable deep water properties, together with the EAP, can partly explain the strength of the Subpolar Gyre circulation.

Medhaug, I.; Langehaug, H. R.; Eldevik, T.; Otterâ, O. H.; Furevik, T.; Bentsen, M.

2012-04-01

96

Observations of decadal time scale salinity changes in the subtropical thermocline of the North Pacific Ocean  

E-print Network

Observations of decadal time scale salinity changes in the subtropical thermocline of the North Mixed layer Hydrological cycle a b s t r a c t Data from Argo floats indicate that significant salinity decades, including observations obtained as part of the WOCE hydrographic program. Such a salinity

Riser, Stephen C.

97

The Hydroclimate of East Africa: Seasonal cycle, Decadal Variability, and Human-induced Climate Change  

NASA Astrophysics Data System (ADS)

The hydroclimate of East Africa shows distinctive variabilities on seasonal to decadal time scales and poses a great challenge to climatologists attempting to project its response to anthropogenic emissions of greenhouse gases (GHGs). Increased frequency and intensity of droughts over East Africa in recent decades raise the question of whether the drying trend will continue into the future. To address this question, we first examine the decadal variability of the East African rainfall during March--May (MAM, the major rainy season in East Africa) and assess how well a series of models simulate the observed features. Observational results show that the drying trend during MAM is associated with decadal natural variability of sea surface temperature (SST) variations over the Pacific Ocean. The multimodel mean of the SST-forced, Coupled Model Intercomparison Project Phase 5 (CMIP5) AMIP experiment models reproduces both the climatological annual cycle and the drying trend in recent decades. The fully coupled models from the CMIP5 historical experiment, however, have systematic errors in simulating the East African rainfall annual cycle by underestimating the MAM rainfall while overestimating the October--December (OND, the second rainy season in East Africa) rainfall. The multimodel mean of the historical coupled runs of the MAM rainfall anomalies, which is the best estimate of the radiatively-forced change, shows a weak wetting trend associated with anthropogenic forcing. However, the SST anomaly pattern associated with the MAM rainfall has large discrepancies with the observations. The errors in simulating the East African hydroclimate with coupled models raise questions about how reliable model projections of future East African climate are. This motivates a fundamental study of why East African climate is the way it is and why coupled models get it wrong. East African hydroclimate is characterized by a dry annual mean climatology compared to other deep tropical land areas and a bimodal annual cycle with the major rainy season during MAM (often called the ``long rains'' by local people) and the second during OND (the "short rains"). To explore these distinctive features, we use the ERA-Interim Re-Analysis data to analyze the associated annual cycles of atmospheric convective stability, circulation and moisture budget. The atmosphere over East Africa is found to be convectively stable, in general, year-round but with an annual cycle dominated by the surface moist static energy (MSE), which is in phase with the precipitation annual cycle. Throughout the year, the atmospheric circulation is dominated by a pattern of convergence near the surface, divergence in the lower troposphere and convergence again at upper levels. Consistently, the convergence of the vertically integrated moisture flux is mostly negative across the year, but becomes weakly positive in the two rainy seasons. It is suggested the semi-arid/arid climate in East Africa and its bimodal rainfall annual cycle can be explained by the ventilation mechanism, in which the atmospheric convective stability over East Africa is controlled by the import of low MSE air from the relatively cool Indian Ocean off the coast and the cold winter hemisphere. During the rainy seasons, however, the off-coast SST increases (and is warmest during the long rains season) and the northerly or southerly weakens, and consequently the air imported into East Africa becomes less stable. The MSE framework is then applied to study the coupling-induced bias of the East African rainfall annual cycle often found in CMIP3/5 coupled models that overestimates the OND rainfall and underestimates the MAM rainfall, by comparing the historical (coupled) and the AMIP runs (SST-forced) for each model. It is found that a warm north and cold south SST bias over the Indian Ocean induced in coupled models is responsible for the dry MAM rainfall bias over East Africa while the ocean dynamics induced warm west and cold east SST bias over the Indian Ocean contributes to the wet OND rainfall bias in

Yang, Wenchang

98

Regime Change in the Pacific Ocean and the Relative Intensities of Multi-Decadal and Quasi-Centennial Variability  

NASA Astrophysics Data System (ADS)

Fish scales deposited in varves in the Santa Barbara Basin off the coast of California suggest that both Pacific Sardine (Sardinops sagax) and Northern Anchovy (Engraulis mordax) populations vary with common characteristic periodicities of 58, 72-77, and 102-106 years [Baumgartner et al., 1992]. Variability of sardine populations on 30-70 year scales also has been observed since the mid 17th century off the coast of Japan [Yasuda, 1997]. These periodicities in population are thought to be climatically driven. While the 58 year and possibly the 72-77 year "multi-decadal" cycles are observable in modern instrument- derived records of the Pacific Decadal Oscillation (PDO) index, the 102-106 year "quasi-centennial" cycle is less apparent. Recently, Shen et al. [2006] presented a reconstruction of the PDO index since 1470 based on eastern China rainfall in which the quasi-centennial periodicity was more apparent before 1850. Using empirical mode decomposition (EMD, Huang et al., 1998) of the PDO reconstruction, we confirm this result. We then use EMD to analyze a white spruce (Picea glauca) tree ring record from Kobuk/Noatak, Alaska, which correlates with the April PDO index. The results show that multidecadal and quasi-centennial variability in this proxy record were similar in magnitude during the Little Ice Age but that multi-decadal variability dominated during both the Medieval Warm Period and since 1850. Based on this limited analysis, we suggest the possibility that multi-decadal variability in the Pacific Ocean could be enhanced by anthropogenic climate change. Changes in ocean circulation of this type are a major unknown in future climate forecasts. Additionally, we propose that these changes in the dominant periodicities of decadal to centennial variability over time may represent significant changes in Pacific Ocean circulation. Indeed, these regime changes may explain the multi-centennial variability in the covariance of particular Pacific fish populations found by various workers. It is unclear from the limited data available whether the apparent covariance of these shifts with centennial-scale anomalies in solar activity (such as the Medieval Maximum and the Maunder Minimum) are coincidental.

Heavens, N. G.; Yung, Y. L.

2006-12-01

99

Linkage between the Pacific Decadal Oscillation and the low frequency variability of the Pacific Subtropical Cell  

NASA Astrophysics Data System (ADS)

The decadal variability of Pacific Subtropical Cell (STC) and its linkages with the Pacific Decadal Oscillation (PDO) are investigated in the present study based on a Simple Ocean Data Assimilation (SODA 2.2.4). It is found that, on decadal time scales, the western boundary and interior pycnocline transports are anticorrelated and the variation of the interior component is more significant, which is consistent with previous studies. The decadal variability of STC in the Northern Hemisphere is found to be strongly associated with PDO. Associated with a positive (negative) phase of PDO, the relaxation (acceleration) of the northeast trades slows down (spins up) the STC within a few years through baroclinic adjustment in conjunction with the subduction of the cold (warm) mixed-layer anomalies in the extratropics. The cold (warm) water is then injected into the thermocline and advected further southwestward to the tropics along the isopycnal surfaces, leading to the slowdown (spin-up) of STC due to zonal pressure gradient change at low latitude. Along with the STC weakening (strengthening), a significant warming (cold) anomaly appears in the tropics and it is advected to the midlatitude by the Kuroshio and North Pacific currents, thus feeding back to the atmosphere over the North Pacific. In contrast to the Northern Hemisphere, it is found the STC in the south only passively responds to the PDO. The mechanism found here highlights the role of the STC advection of extratropical anomalies to the tropics and horizontal gyre advection of the tropical anomalies to the extratropics in decadal variability of the STC and PDO.

Hong, Lingya; Zhang, Liping; Chen, Zhaohui; Wu, Lixin

2014-06-01

100

Associations of multi-decadal sea-surface temperature variability with US drought  

USGS Publications Warehouse

Recent research suggests a link between drought occurrence in the conterminous United States (US) and sea surface temperature (SST) variability in both the tropical Pacific and North Atlantic Oceans on decadal to multidecadal (D2M) time scales. Results show that the Atlantic Multidecadal Oscillation (AMO) is the most consistent indicator of D2M drought variability in the conterminous US during the 20th century, but during the 19th century the tropical Pacific is a more consistent indicator of D2 M drought. The interaction between El Nin??o-Southern Oscillation (ENSO) and the AMO explain a large part of the D2M drought variability in the conterminous US. More modeling studies are needed to reveal possible mechanisms linking low-frequency ENSO variability and the AMO with drought in the conterminous US. ?? 2007 Elsevier Ltd and INQUA.

McCabe, G.J.; Betancourt, J.L.; Gray, S.T.; Palecki, M.A.; Hidalgo, H.G.

2008-01-01

101

Variability of Ocean Heat Uptake: Reconciling Observations and Models  

SciTech Connect

This study examines the temporal variability of ocean heat uptake in observations and in climate models. Previous work suggests that coupled Atmosphere-Ocean General Circulation Models (A-OGCMs) may have underestimated the observed natural variability of ocean heat content, particularly on decadal and longer timescales. To address this issue, we rely on observed estimates of heat content from the 2004 World Ocean Atlas (WOA-2004) compiled by Levitus et al. (2005). Given information about the distribution of observations in WOA-2004, we evaluate the effects of sparse observational coverage and the infilling that Levitus et al. use to produce the spatially-complete temperature fields required to compute heat content variations. We first show that in ocean basins with limited observational coverage, there are important differences between ocean temperature variability estimated from observed and infilled portions of the basin. We then employ data from control simulations performed with eight different A-OGCMs as a test-bed for studying the effects of sparse, space- and time-varying observational coverage. Subsampling model data with actual observational coverage has a large impact on the inferred temperature variability in the top 300 and 3000 meters of the ocean. This arises from changes in both sampling depth and in the geographical areas sampled. Our results illustrate that subsampling model data at the locations of available observations increases the variability, reducing the discrepancy between models and observations.

AchutaRao, K M; Santer, B D; Gleckler, P J; Taylor, K; Pierce, D; Barnett, T; Wigley, T L

2005-05-05

102

Rule-based System Architecting of Earth Observing Systems: The Earth Science Decadal Survey  

E-print Network

Rule-based System Architecting of Earth Observing Systems: The Earth Science Decadal Survey Daniel satellite systems, and applies it to the Earth Science Decadal Survey. The architecting problem In 2004, the NASA Office of Earth Science, the National Oceanic and Atmospheric Administration (NOAA

de Weck, Olivier L.

103

Changes of Pacific decadal variability in the twentieth century driven by internal variability, greenhouse gases, and aerosols  

NASA Astrophysics Data System (ADS)

This paper explores the contributions of internal variability, greenhouse gases (GHGs), and anthropogenic aerosols (AAs) in driving the magnitude and evolution of Pacific Decadal Variability (PDV) during the twentieth century by analyzing 129 Coupled Model Intercomparison Project Phase 5 model realizations. Evidence shows that PDV phase transition is dominated by internal variability, but it is also significantly affected by external forcing agents such as GHGs and aerosols. The combined effects of GHGs and AAs favor the positive phase of PDV with stronger ocean warming in the tropics than the extratropical Pacific. The GHG forcing induces the increased surface downward longwave radiation, especially over the tropical Pacific, and results in stronger warming in that area. The AA forcing results in a stronger cooling in the North Pacific region, due to the reduced surface downward shortwave radiation via cloud-aerosol interaction: this offsets the substantial warming caused by GHG forcing.

Dong, Lu; Zhou, Tianjun; Chen, Xiaolong

2014-12-01

104

Southern ocean SST variability and its relationship with ENSO on inter-decadal time scales  

NASA Astrophysics Data System (ADS)

Empirical orthogonal function (EOF) analysis reveals a co-variability of Sea surface temperatures (SSTs) in the Southern Hemisphere (0°-60°S). In the South Indian and Atlantic Oceans, there is a subtropical dipole pattern slanted in the southwest-northeast direction. In the South Pacific Ocean, a meridional tripole structure emerges, whose middle pole co-varies with the dipoles in the South Indian and Atlantic Oceans and is used in this study to track subtropical Pacific variability. The South Indian and Atlantic Ocean dipoles and the subtropical Pacific variability are phase-locked in austral summer. On the inter-decadal time scales, the dipoles in the South Indian and Atlantic Oceans weaken in amplitude after 1979/1980. No such weakening is found in the subtropical South Pacific Ocean. Interestingly, despite the reduced amplitude, the correlation of the Indian Ocean and Atlantic dipoles with El Niño and Southern Oscillation (ENSO) are enhanced after 1979/1980. The same increase in correlation is found for subtropical South Pacific variability after 1979/1980. These inter-decadal modulations imply that the Southern Hemisphere participates in part of the climate shift in the late 1970s. The correlation between Southern Hemisphere SST and ENSO reduces after 2000.

Yan, Li; Du, Yan; Zhang, Lan

2013-06-01

105

Decadal variability in Gulf of Mexico sea surface temperatures since 1734 CE  

NASA Astrophysics Data System (ADS)

The Gulf of Mexico is a major source of moisture to North America and is a source region for the Gulf Stream, which transports ocean heat northward. Sea surface temperature (SST) variations on centennial to millennial time scales have been documented for this region using paleoceanographic proxies; however, records capable of resolving decadal to subannual variability are lacking. Here we present 274 years of monthly-resolved SST variations derived from records of strontium-to-calcium ratios (Sr/Ca) extracted from four Siderastrea siderea cores recovered from coral colonies within the Dry Tortugas National Park (24°42?N, 82°48?W) in the Gulf of Mexico. We find no significant difference in mean Sr/Ca among these cores and significant correlation between cores (r ? 0.90, p ? 0.05 for monthly). The cross-dated chronology, determined by counting annual bands and correlating Sr/Ca variations, agrees with four 230Th dates within ±2? analytical precision. Calibration and verification of our multi-core coral Sr/Ca record with local temperature records reveals high agreement (Sr/Ca = -0.042 SST + 10.074, R2 = 0.96; ?regression = 0.70°C, 1?), similar to those reported for single cores from this location. We find winter SSTs tend to be more variable than summer SSTs (0.99 and 0.81°C, 1?; respectively) with periodic intervals of 10 to 15 years with cooler summer temperatures. The average reconstructed SST during the Little Ice Age (LIA; 1734-1880 CE) is colder (-0.82°C) than that during the late twentieth century (1971-2000 CE). The amplitude of decadal-scale variability (1 to 2.5°C) in the LIA is larger compared to similar scale variability in the twentieth century. The secular trend and decadal-scale variability in our reconstruction is broadly similar to an ~ decadally-resolved (~12 years/sample) Mg/Ca record from planktic foraminifer in the northern Gulf of Mexico (Richey et al., 2007), thus further confirming the reconstructed patterns of temperature variability in the Gulf of Mexico during the LIA.

DeLong, K. L.; Maupin, C. R.; Flannery, J. A.; Quinn, T. M.; lin, K.; Shen, C.

2012-12-01

106

Decadal response of the Kuroshio Extension jet to Rossby waves: Observation and thin-jet theory  

NASA Astrophysics Data System (ADS)

This study examines interannual to decadal variability of the Kuroshio Extension (KE) jet using satellite altimeter observations from 1993 to 2010. The leading Empirical Orthogonal Function (EOF) mode of sea level variability in the KE region represents the meridional shift of the KE jet, followed by its strength changes with a few month lag. This result indicates that the latitude changes of the KE jet are a key process in the decadal variability in the KE region. The meridional shift of the KE jet lags atmospheric fluctuations over the eastern North Pacific by about three years. Broad sea level anomalies (SLAs) emerge in the eastern North Pacific 3-4 years before the upstream KE jet shift, and propagate westward along the KE jet axis. It is worth emphasizing that the meridional scale of the SLAs gradually narrows, and their amplitude increases in the course of the propagation. This westward propagation of SLAs with a phase speed of about 5 cm/s is attributed to the westward propagation of the meridional shift of the jet, consistent with the thin-jet theory, whose importance has been suggested by previous numerical studies. In addition, it is revealed that the changes of the meridional scale and amplitude of the SLAs during the propagation are also consistent with the changes of the climatological KE jet structure. Interestingly, the westward propagating signals tend to conserve their quasi-geostrophic potential vorticity anomaly, which may explain the characteristic changes of SLAs during the propagation. After the westward propagating signals of positive (negative) SLAs reach at the east coast of Japan, the upstream KE jet strengthens (weakens) associated with the strength changes of the northern and southern recirculation gyres. This strength change of the KE jet propagates eastward with a phase speed of about 6 cm/s, suggesting an importance of advection of potential vorticity by the current in response to the incoming westward propagating signals along the KE jet axis.Lag regressions of sea level anomalies of the satellite observation onto the KE jet latitude, where negative lag means that the KE jet latitude lags sea level anomalies

Sasaki, Y. N.; Minobe, S.; Schneider, N.

2012-12-01

107

Tropical pacific forcing of decadal SST variability in the western indian ocean over the past two centuries  

PubMed

A 194-year annual record of skeletal delta(18)O from a coral growing at Malindi, Kenya, preserves a history of sea surface temperature (SST) change that is coherent with instrumental and proxy records of tropical Pacific climate variability over interannual to decadal periods. This variability is superimposed on a warming of as much as 1.3 degrees C since the early 1800s. These results suggest that the tropical Pacific imparts substantial decadal climate variability to the western Indian Ocean and, by implication, may force decadal variability in other regions with strong El Nino-Southern Oscillation teleconnections. PMID:10649987

Cole; Dunbar; McClanahan; Muthiga

2000-01-28

108

Inter-Decadal to Multi-Decadal Sea Surface Temperature Variability in the Southwest Tropical Pacific Since AD 1648  

Microsoft Academic Search

The southwest tropical Pacific is a region with temporally and spatially sparse sea surface temperature (SST) records that limit investigations of climate variability on interannual to centennial time scales for this region. We present a monthly resolved coral Sr\\/Ca record from 1648 to 1999 from Amédée Island, New Caledonia (22.48°S, 166.47°E), and reconstruct SST variability in the southwest Pacific for

K. L. Delong; T. M. Quinn; F. W. Taylor; K. Lin; C. Shen

2008-01-01

109

Anthropogenic Forcing and Decadal Climate Variability in Sensitivity Experiments of Twentieth- and Twenty-First-Century Climate.  

NASA Astrophysics Data System (ADS)

A methodology is formulated to evaluate the possible changes in decadal-timescale (10-20-yr period) surface temperature variability and associated low-frequency fluctuations of anthropogenic forcing and changes in climate base state due to the forcing in simulations of twentieth- and twenty-first-century climate in a global coupled climate model without flux adjustment. The two climate change experiments both start in the year 1900. The first uses greenhouse gas radiative forcing (represented by equivalent CO2) observed during the twentieth century, and extends greenhouse gas forcing to the year 2035 by increasing CO2 1% yr1 compound after 1990 (CO2-only experiment). The second includes the same greenhouse gas forcing as the first, but adds the effects of time-varying geographic distributions of monthly sulfate aerosol radiative forcing represented by a change in surface albedo (CO2 + sulfates experiment). The climate change experiments are compared with a 135-yr control experiment with no change in external forcing. Climate system responses in the CO2-only and CO2 + sulfates experiments in this particular model are marked not only by greater warming at high latitudes in the winter hemisphere, but also by a global El Niño-like pattern in surface temperature, precipitation, and sea level pressure. This pattern is characterized by a relatively greater increase of SST in the central and eastern equatorial Pacific in comparison with the west, a shift of precipitation maxima from the western Pacific to the central Pacific, mostly decreases of Asian-Australian monsoon strength, lower pressure over the eastern tropical Pacific, deeper midlatitude troughs in the North and South Pacific, and higher pressure over Australasia. Time series analysis of globally averaged temperature and an EOF analysis of surface temperature are consistent with previous results in that enhanced low-frequency variability with periods greater than around 20 yr is introduced into the model coupled climate system with a comparable timescale to the forcing. To examine the possible effects of the associated changes in base state on decadal timescale variability (10-20-yr periods), the surface temperature time series are filtered to retain only variability on that timescale. The El Niño-like pattern of decadal variability seen in the observations is present in each of the model experiments (control, CO2 only, and CO2 + sulfates), but the magnitude decreases significantly in the CO2-only experiment. This decrease is associated with changes in the base-state climate that include a reduction in the magnitude (roughly 5%-20% or more) of wind stress and ocean currents in the upper 100 m in most ocean basins and a weakening of meridional overturning (about 50%) in the Atlantic. These weakened circulation features contribute to decreasing the amplitude of global decadal surface temperature variability as seen in a previous sea-ice sensitivity study with this model. Thus the superposition of low-frequency variability patterns in the radiative forcing increases climate variability for periods comparable to those of the forcing (greater than about 20 yr). However, there are decreases in the amplitude of future decadal (10-20-yr period) variability in these experiments due to changes of the base-state climate as a consequence of increases in that forcing.

Meehl, Gerald A.; Washington, Warren M.; Arblaster, Julie M.; Bettge, Thomas W.; Strand, Warren G., Jr.

2000-11-01

110

Ocean surface temperature variability: large model-data differences at decadal and longer periods.  

PubMed

The variability of sea surface temperatures (SSTs) at multidecadal and longer timescales is poorly constrained, primarily because instrumental records are short and proxy records are noisy. Through applying a new noise filtering technique to a global network of late Holocene SST proxies, we estimate SST variability between annual and millennial timescales. Filtered estimates of SST variability obtained from coral, foraminifer, and alkenone records are shown to be consistent with one another and with instrumental records in the frequency bands at which they overlap. General circulation models, however, simulate SST variability that is systematically smaller than instrumental and proxy-based estimates. Discrepancies in variability are largest at low latitudes and increase with timescale, reaching two orders of magnitude for tropical variability at millennial timescales. This result implies major deficiencies in observational estimates or model simulations, or both, and has implications for the attribution of past variations and prediction of future change. PMID:25385623

Laepple, Thomas; Huybers, Peter

2014-11-25

111

Decadal Variability in the North Atlantic Ocean Involving Ocean-Atmosphere Interactions  

NASA Astrophysics Data System (ADS)

Variability in the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) are shaping the North Atlantic basin and European climate on time-scales of decades and longer. Fifty years (1950-1999) of NCEP/NCAR individual monthly reanalysis products and other data (e.g., AO index of Thompson et al. 1998, GRL) are used to describe decadal climate variability in the North Atlantic basin that involves ocean-atmosphere interactions. The interaction between the ocean and atmosphere was investigated using the Smith et al. (1996, JCL) reconstructed sea-surface temperature (SST), and sea level pressure (SLP). The study period of Jan 1950-Dec 1999 contains 600 individual months. This presentation will address the details of SST-SLP-AO association at low frequencies in the North Atlantic. SST and AO/SLP are used as indicators of upper ocean and surface atmospheric variability, respectively. The dominant decadal coupled ocean-atmosphere covariability modes were identified from a canonical correlation analysis (CCA) between SST and SLP gridded fields. Before applying CCA, the SST and SLP data were prepared in the following manner: (a) for each grid point and for each individual month, anomalies were computed with respect to the mean climatological values derived for the given calendar month; (b) for each grid point and for a given month, the gridded time series anomalies were normalized by the temporal standard deviation of the calendar month; (c) a 61-term low-pass Lanczos filter was applied to the gridded standardized departures to retain only the low frequencies (periods greater than 5 years) (Duchon 1979, JAM); and (d) we performed EOF analysis of both SST and SLP fields to capture spatial coherent variability. Only the first 6 EOFs of SST and first 5 EOFs of SLP were retained as input to the CCA procedure. The SST canonical mode has a dipole-like structure with maximum positive amplitudes in the central-western Atlantic, and minimum amplitudes southeast of Greenland. The SLP mode reflects AO/NAO pattern. These SST and SLP CCA patterns are similar to those derived by Dima et al. (2001, JCL). Spectra of these CCA time series exhibit significant peaks at a period of about 12 years. This diagnostic study also seeks to contribute to our understanding to how the North Atlantic atmospheric circulation would respond to forcing by the ocean on decadal time-scales, and to determine the extent to which SST anomalies feed back on the atmospheric circulation. The nature of the AO variability and ocean- atmosphere interaction on longer time-scales was investigated by computing a CCA-based monthly cross-correlation lag-lead function among the low frequency AO index and the dominant CCA modes of SST and SLP. Significant correlations are found with either the SST leading the SLP/AO atmospheric field or the SLP/AO leading the SST oceanic field. Our results suggest that there is coherent interaction among the AO, the ocean and the atmosphere on longer time-scales. The decadal mode, which involves AO/NAO, is consistent with the coupled ocean-atmosphere model results of Grotzner et al. (1998, JCL). We will also investigate the relationships of the low frequency variability of the winter storm track over the North Atlantic basin to low frequency variability of SLP, SST and the AO/NAO circulations. This will be made possible with recently constructed monthly cyclone density fields (after Serreze et al. 1997, JCL).

El Hamly, M.; Lamb, P. J.

2001-12-01

112

Observations of Suspected RR Lyrae Variable Stars  

NASA Astrophysics Data System (ADS)

Our group is working on confirming variability of suspected RR Lyrae variables we have identified, and making follow-up observations of confirmed new variables. We developed a new method of detecting RR Lyrae variable stars using only a single epoch of both photometry and spectroscopy taken from the Sloan Digital Sky Survey (SDSS). The method takes advantage of clear departures from the template norm for stars that have photometry and spectroscopy taken out of phase. Over 1,000 stars have been identified as probable RR Lyrae stars, scattered across the halo and ranging from 14th to 20th magnitude. This paper describes observations taken at McDonald Observatory by undergraduate students as part of this project. We will discuss how and why the method works, and our McDonald observations to confirm variability and obtain full lightcurves.

Smith, Stephanie; Powell, W. L.; Wilhelm, R. J.; De Lee, N. M.

2014-01-01

113

Local and remote forcing of decadal sea level and thermocline depth variability in the South Indian Ocean  

NASA Astrophysics Data System (ADS)

AbstractAnalysis is performed on a set of diagnostic numerical experiments designed to isolate local Indian Ocean forcing versus remote forcing from the Pacific via the Indonesian throughflow on <span class="hlt">decadal</span> <span class="hlt">variability</span> of subsurface temperature, sea level, and thermocline depth of the South Indian Ocean. It is found that the vertical structure of <span class="hlt">decadal</span> temperature <span class="hlt">variability</span> varies from <span class="hlt">decade-to-decade</span>, with maximum variation peaking in the vicinity of the thermocline. The <span class="hlt">decadal</span>-scale temperature variations in the tropical southwestern Indian Ocean between 5°S and 17°S are primarily associated with the vertical displacements of the thermocline. Prior to the early 1990s, <span class="hlt">decadal</span> variations in sea level and thermocline depth can be described in terms of a baroclinic Sverdrup balance, forced by Ekman pumping velocity associated with windstress curl acting on the Indian Ocean. Beginning in the early 1990s, <span class="hlt">decadal</span> <span class="hlt">variability</span> of the equatorial Pacific trades forces thermocline variations that modify the sea level and thermocline depth across the tropical South Indian Ocean basin. Farther south, between 20°S and 30°S, oceanic internal <span class="hlt">variability</span> makes significant contributions to <span class="hlt">decadal</span> <span class="hlt">variability</span> of the thermocline. The anomalies along the western coast of Australia are primarily driven by regional forcing acting on the Indian Ocean prior to the 1990s, and signals originating from the equatorial Pacific make a greater contribution thereafter.</p> <div class="credits"> <p class="dwt_author">Trenary, Laurie L.; Han, Weiqing</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">114</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015DSRI...95...85S"> <span id="translatedtitle">Interannual to <span class="hlt">decadal</span> oxygen <span class="hlt">variability</span> in the mid-depth water masses of the eastern North Atlantic</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The detection of multi-<span class="hlt">decadal</span> trends in the oceanic oxygen content and its possible attribution to global warming is protracted by the presence of a substantial amount of interannual to <span class="hlt">decadal</span> <span class="hlt">variability</span>, which hitherto is poorly known and characterized. Here we address this gap by studying interannual to <span class="hlt">decadal</span> changes of the oxygen concentration in the Subpolar Mode Water (SPMW), the Intermediate Water (IW) and the Mediterranean Outflow Water (MOW) in the eastern North Atlantic. We use data from a hydrographic section located in the eastern North Atlantic at about 48°N repeated 12 times over a period of 19 years from 1993 through 2011, with a nearly annual resolution up to 2005. Despite a substantial amount of year-to-year <span class="hlt">variability</span>, we <span class="hlt">observe</span> a long-term decrease in the oxygen concentration of all three water masses, with the largest changes occurring from 1993 to 2002. During that time period, the trends were mainly caused by a contraction of the subpolar gyre associated with a northwestward shift of the Subpolar Front (SPF) in the eastern North Atlantic. This caused SPMW to be ventilated at lighter densities and its original density range being invaded by subtropical waters with substantially lower oxygen concentrations. The contraction of the subpolar gyre reduced also the penetration of IW of subpolar origin into the region in favor of an increased northward transport of IW of subtropical origin, which is also lower in oxygen. The long-term oxygen changes in the MOW were mainly affected by the interplay between circulation and solubility changes. Besides the long-term signals, mesoscale <span class="hlt">variability</span> leaves a substantial imprint as well, affecting the water column over at least the upper 1000 m and laterally by more than 400 km. Mesoscale eddies induced changes in the oxygen concentration of a magnitude that can substantially alias analyses of long-term changes based on repeat hydrographic data that are being collected at intervals of typically 10 years.</p> <div class="credits"> <p class="dwt_author">Stendardo, Ilaria; Kieke, Dagmar; Rhein, Monika; Gruber, Nicolas; Steinfeldt, Reiner</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">115</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014BGD....11.7685B"> <span id="translatedtitle">Land surface phenological response to <span class="hlt">decadal</span> climate <span class="hlt">variability</span> across Australia using satellite remote sensing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Land surface phenological cycles of vegetation greening and browning are influenced by <span class="hlt">variability</span> in climatic forcing. Quantitative information on phenological cycles and their <span class="hlt">variability</span> is important for agricultural applications, wildfire fuel accumulation, land management, land surface modeling, and climate change studies. Most phenology studies have focused on temperature-driven Northern Hemisphere systems, where phenology shows annually reoccurring patterns. Yet, precipitation-driven non-annual phenology of arid and semi-arid systems (i.e. drylands) received much less attention, despite the fact that they cover more than 30% of the global land surface. Here we focused on Australia, the driest inhabited continent with one of the most <span class="hlt">variable</span> rainfall climates in the world and vast areas of dryland systems. Detailed and internally consistent studies investigating phenological cycles and their response to climate <span class="hlt">variability</span> across the entire continent designed specifically for Australian dryland conditions are missing. To fill this knowledge gap and to advance phenological research, we used existing methods more effectively to study geographic and climate-driven <span class="hlt">variability</span> in phenology over Australia. We linked derived phenological metrics with rainfall and the Southern Oscillation Index (SOI). We based our analysis on Enhanced Vegetation Index (EVI) data from the MODerate Resolution Imaging Spectroradiometer (MODIS) from 2000 to 2013, which included extreme drought and wet years. We conducted a continent-wide investigation of the link between phenology and climate <span class="hlt">variability</span> and a more detailed investigation over the Murray-Darling Basin (MDB), the primary agricultural area and largest river catchment of Australia. Results showed high inter- and intra-annual <span class="hlt">variability</span> in phenological cycles. Phenological cycle peaks occurred not only during the austral summer but at any time of the year, and their timing varied by more than a month in the interior of the continent. The phenological cycle peak magnitude and integrated greenness were most significantly correlated with monthly SOI within the preceding 12 months. Correlation patterns occurred primarily over north-eastern Australia and within the MDB predominantly over natural land cover and particularly in floodplain and wetland areas. Integrated greenness of the phenological cycles (surrogate of productivity) showed positive anomalies of more than two standard deviations over most of eastern Australia in 2009-2010, which coincided with the transition between the El Niño induced <span class="hlt">decadal</span> droughts to flooding caused by La Niña. The quantified spatial-temporal <span class="hlt">variability</span> in phenology across Australia in response to climate <span class="hlt">variability</span> presented here provides important information for land management and climate change studies and applications.</p> <div class="credits"> <p class="dwt_author">Broich, M.; Huete, A.; Tulbure, M. G.; Ma, X.; Xin, Q.; Paget, M.; Restrepo-Coupe, N.; Davies, K.; Devadas, R.; Held, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">116</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EPSC....9...62F"> <span id="translatedtitle">Seasonal Evolution of Saturn's Polar Atmosphere from a <span class="hlt">Decade</span> of Cassini/CIRS <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Saturn's polar regions are subjected to extreme insolation variations over its 29.5 year orbit due to the gas giant's 26-degree axial tilt, causing seasonal changes to the thermal structure, chemistry, dynamics and cloud properties of the polar environments. Cassini's high inclination orbits permit detailed scrutiny of Saturn's high latitudes in a dataset that now spans a <span class="hlt">decade</span> (a third of a Saturn year, 2004-2014), five years either side of the northern spring equinox in 2009. Thermal infrared Cassini/CIRS spectra (7-16 ?m) from all mission phases are inverted to determine the rate of change of polar temperatures, wind shears, tropospheric phosphine (as a tracer of vertical mixing) and stratospheric hydrocarbons (tracers of middle atmospheric circulation and chemistry). Cassini's unique vantage point allows us to track these parameters as the summer southern pole receded into autumn and the winter northern pole emerged into spring sunlight. Results show the most rapid changes to temperature and composition occurring poleward of 70o in each hemisphere, in excess of expectations from simple radiative climate models. Small cyclonic vortices persist at both poles throughout theCassini mission, while the broad stratospheric vortices are seasonally <span class="hlt">variable</span>. The signature of the northern hexagon is still present in the tropospheric thermal structure. At the time of writing, an infraredbright polar vortex is beginning to emerge at the northern spring pole, consistent with the historical record of Saturn <span class="hlt">observations</span> from the 1980s (previous northern spring, [4]).</p> <div class="credits"> <p class="dwt_author">Fletcher, L. N.; Sinclair, J. A.; Irwin, P. G. J.; Giles, R. S.; Orton, G. S.; Hesman, B. E.; Hurley, J.; Bjoraker, G. L.; Simon, A. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">117</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.H52G..07C"> <span id="translatedtitle">A Robust Decision-Making Technique for Water Management under <span class="hlt">Decadal</span> Scale Climate <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Robust decision making, a flexible and dynamic approach to managing water resources in light of deep uncertainties associated with climate <span class="hlt">variability</span> at inter-annual to <span class="hlt">decadal</span> time scales, is an analytical framework that detects when a system is in or approaching a vulnerable state. It provides decision makers the opportunity to implement strategies that both address the vulnerabilities and perform well over a wide range of plausible future scenarios. A strategy that performs acceptably over a wide range of possible future states is not likely to be optimal with respect to the actual future state. The degree of success--the ability to avoid vulnerable states and operate efficiently--thus depends on the skill in projecting future states and the ability to select the most efficient strategies to address vulnerabilities. This research develops a robust decision making framework that incorporates new methods of <span class="hlt">decadal</span> scale projections with selection of efficient strategies. Previous approaches to water resources planning under inter-annual climate <span class="hlt">variability</span> combining skillful seasonal flow forecasts with climatology for subsequent years are not skillful for medium term (i.e. <span class="hlt">decadal</span> scale) projections as decision makers are not able to plan adequately to avoid vulnerabilities. We address this need by integrating skillful <span class="hlt">decadal</span> scale streamflow projections into the robust decision making framework and making the probability distribution of this projection available to the decision making logic. The range of possible future hydrologic scenarios can be defined using a variety of nonparametric methods. Once defined, an ensemble projection of <span class="hlt">decadal</span> flow scenarios are generated from a wavelet-based spectral K-nearest-neighbor resampling approach using historical and paleo-reconstructed data. This method has been shown to generate skillful medium term projections with a rich variety of natural <span class="hlt">variability</span>. The current state of the system in combination with the probability distribution of the projected flow ensembles enables the selection of appropriate decision options. This process is repeated for each year of the planning horizon--resulting in system outcomes that can be evaluated on their performance and resiliency. The research utilizes the RiverSMART suite of software modeling and analysis tools developed under the Bureau of Reclamation's WaterSMART initiative and built around the RiverWare modeling environment. A case study is developed for the Gunnison and Upper Colorado River Basins. The ability to mitigate vulnerability using the framework is gauged by system performance indicators that measure the ability of the system to meet various water demands (i.e. agriculture, environmental flows, hydropower etc.). Options and strategies for addressing vulnerabilities include measures such as conservation, reallocation and adjustments to operational policy. In addition to being able to mitigate vulnerabilities, options and strategies are evaluated based on benefits, costs and reliability. Flow ensembles are also simulated to incorporate mean and variance from climate change projections for the planning horizon and the above robust decision-making framework is applied to evaluate its performance under changing climate.</p> <div class="credits"> <p class="dwt_author">Callihan, L.; Zagona, E. A.; Rajagopalan, B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">118</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1989ovsg.book.....L"> <span id="translatedtitle"><span class="hlt">Observing</span> <span class="hlt">variable</span> stars. A guide for beginners</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">David Levy's entertaining, well-researched book is aimed at the amateur enthusiast who likes to learn enjoyably. Beginning with advice on binoculars and telescopes, and how to <span class="hlt">observe</span> the night sky effectively, the author goes on to describe thoroughly the field of <span class="hlt">variable</span> star <span class="hlt">observation</span>, a field in which amateurs have made important contributions. He shows how to interpret variations in light output in terms of the life of a star, from birth through to sometimes violent death. All of the major <span class="hlt">variable</span> stars are described and classified, as well as other <span class="hlt">variable</span> objects such as active galaxies, asteroids, comets and the sun. The book also contains a guide to the seasonal night sky. Throughout, practical <span class="hlt">observations</span> serve to complement the text, producing an exciting, very readable introduction to this fascinating subject.</p> <div class="credits"> <p class="dwt_author">Levy, David H.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">119</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AGUFM.H23G1314S"> <span id="translatedtitle"><span class="hlt">Decadal</span> Predictability in the Colorado River Basin Using <span class="hlt">Observed</span> and Reconstructed Records</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Pacific <span class="hlt">Decadal</span> Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) climate indices have been used extensively in a variety of hydroclimate analyses to investigate <span class="hlt">decadal</span> predictability of regional climate and water cycle dynamics. One such example shows a strong relationship between the phases of these indices and streamflow at Lee’s Ferry along the Colorado River. With this apparent connection, there is an implication that these indices could be used to forecast the next <span class="hlt">decade</span> of streamflow at Lee’s Ferry. In this study, PDO and AMO are used to make retrospective forecasts of the 40 most recent ten year running means of Lee’s Ferry streamflow, and we confirm that there is substantially more skill than using the climatology alone. The <span class="hlt">decadal</span> predictions explain 45% of the <span class="hlt">observed</span> variance which is statistically significant at the 99% level. Next, we test whether or not this relationship, and the accompanying forecast skill, has been consistent over a longer period of time than the <span class="hlt">observed</span> record. Existing reconstructions of PDO, AMO and Lee’s Ferry streamflow are used to find that the forecast skill over the reconstructed periods has rarely been as high as what is seen in the <span class="hlt">observed</span> record. Additionally, a wavelet analysis is performed on the <span class="hlt">observed</span> and reconstructed time series. The <span class="hlt">observed</span> records of the three time series all share a dominant multidecadal frequency between 40 and 70 years in length. This might help to explain the skill that is seen in the <span class="hlt">observed</span> record. However, this multidecadal frequency is not persistent in time for any of the reconstructed time series. Therefore, <span class="hlt">decadal</span> predictions at Lee’s Ferry may prove to be more difficult than the <span class="hlt">observed</span> record suggests.</p> <div class="credits"> <p class="dwt_author">Switanek, M.; Troch, P. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">120</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1986JAVSO..15..286W"> <span id="translatedtitle">Swithin St. Cleeve: <span class="hlt">Variable</span> Star <span class="hlt">Observer</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">THomas Hardy's romance "Two on a Tower" is the first novel to use an astronomical background as its unifying theme and the first to cast an astronomer in the role of protagonist. One subplot of the novel concerns Swithin St. Cleeve's quest for fame through his <span class="hlt">observations</span> of <span class="hlt">variable</span> stars. Despite a number of <span class="hlt">observational</span> and instrumental setbacks, he makes an amazing discovery about <span class="hlt">variable</span> stars, one he is certain will excite the astronomical world. But before he can get the news into print, another astronomer announces that very discover and takes from St. Cleeve the fame he thought would be his.</p> <div class="credits"> <p class="dwt_author">Weitzenhoffer, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">1986-12-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_5");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> 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onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_8");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">121</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20130000599&hterms=earth+day&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dearth%2Bday"> <span id="translatedtitle">Temporal <span class="hlt">Variability</span> of <span class="hlt">Observed</span> and Simulated Hyperspectral Earth Reflectance</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is a climate <span class="hlt">observation</span> system designed to study Earth's climate <span class="hlt">variability</span> with unprecedented absolute radiometric accuracy and SI traceability. <span class="hlt">Observation</span> System Simulation Experiments (OSSEs) were developed using GCM output and MODTRAN to simulate CLARREO reflectance measurements during the 21st century as a design tool for the CLARREO hyperspectral shortwave imager. With OSSE simulations of hyperspectral reflectance, Feldman et al. [2011a,b] found that shortwave reflectance is able to detect changes in climate <span class="hlt">variables</span> during the 21st century and improve time-to-detection compared to broadband measurements. The OSSE has been a powerful tool in the design of the CLARREO imager and for understanding the effect of climate change on the spectral <span class="hlt">variability</span> of reflectance, but it is important to evaluate how well the OSSE simulates the Earth's present-day spectral <span class="hlt">variability</span>. For this evaluation we have used hyperspectral reflectance measurements from the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY), a shortwave spectrometer that was operational between March 2002 and April 2012. To study the spectral <span class="hlt">variability</span> of SCIAMACHY-measured and OSSE-simulated reflectance, we used principal component analysis (PCA), a spectral decomposition technique that identifies dominant modes of <span class="hlt">variability</span> in a multivariate data set. Using quantitative comparisons of the OSSE and SCIAMACHY PCs, we have quantified how well the OSSE captures the spectral <span class="hlt">variability</span> of Earth?s climate system at the beginning of the 21st century relative to SCIAMACHY measurements. These results showed that the OSSE and SCIAMACHY data sets share over 99% of their total variance in 2004. Using the PCs and the temporally distributed reflectance spectra projected onto the PCs (PC scores), we can study the temporal <span class="hlt">variability</span> of the <span class="hlt">observed</span> and simulated reflectance spectra. Multivariate time series analysis of the PC scores using techniques such as Singular Spectrum Analysis (SSA) and Multichannel SSA will provide information about the temporal <span class="hlt">variability</span> of the dominant <span class="hlt">variables</span>. Quantitative comparison techniques can evaluate how well the OSSE reproduces the temporal <span class="hlt">variability</span> <span class="hlt">observed</span> by SCIAMACHY spectral reflectance measurements during the first <span class="hlt">decade</span> of the 21st century. PCA of OSSE-simulated reflectance can also be used to study how the dominant spectral <span class="hlt">variables</span> change on centennial scales for forced and unforced climate change scenarios. To have confidence in OSSE predictions of the spectral <span class="hlt">variability</span> of hyperspectral reflectance, it is first necessary for us to evaluate the degree to which the OSSE simulations are able to reproduce the Earth?s present-day spectral <span class="hlt">variability</span>.</p> <div class="credits"> <p class="dwt_author">Roberts, Yolanda; Pilewskie, Peter; Kindel, Bruce; Feldman, Daniel; Collins, William D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">122</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JSR....93..118F"> <span id="translatedtitle">High marsh foraminiferal assemblages' response to intra-<span class="hlt">decadal</span> and multi-<span class="hlt">decadal</span> precipitation <span class="hlt">variability</span>, between 1934 and 2010 (Minho, NW Portugal)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Foraminiferal assemblages of Caminha tidal marshes have been studied since 2002 revealing a peculiar dominance of brackish species, such as Haplophragmoides manilaensis, Haplophragmoides wilberti, Haplophragmoides sp., Pseudothurammina limnetis and Trochamminita salsa/irregularis in the high marshes of the Minho and the Coura lower estuaries. The assemblage composition reflects low salinity conditions, despite the short distance to the estuarine mouth (~ 4 km). However, in May 2010, the presence of salt marsh species Trochammina inflata and Jadammina macrescens became very significant, likely a result of 5 consecutive dry years and a corresponding salinity rise in sediment pore water. Correspondence analysis (CA) groups the surface samples according to their marsh zone, showing a positive correlation with the submersion time of each sampling point. The brackish and normal salinity foraminiferal species appear separated in the CA. This <span class="hlt">observation</span> was applied to the top 10 cm of a high marsh sediment core that corresponds to the period of instrumental record of precipitation and river flow in the Minho region. We found that river flow strongly correlates with precipitation in the Lima and Minho basins. The longer precipitation record was, therefore, used to interpret the foraminiferal assemblages' <span class="hlt">variability</span>. Three main phases were distinguished along ca. 80 years of precipitation data: 1) negative anomalies from 1934 to 1957; 2) positive anomalies from 1958 to 1983; and 3) negative anomalies from 1984 to 2010. This last dryer period exhibits the precipitation maximum and the greatest amplitude of rainfall values. High marsh foraminifera reveals a fast response to these short-term shifts; low salinity species relative abundance increases when precipitation increases over several <span class="hlt">decades</span>, as well as in the same <span class="hlt">decade</span>, in the years of heavy rainfall of dryer periods. High marsh foraminifera records the increase of freshwater flooding and seepage by 1) decreasing abundance and 2) increasing the dominance of low salinity species. On the other hand, low precipitation over ca. 5 years increases the assemblage productivity and the relative abundance of normal salinity species. The positive correlation found between winter precipitation and the NAO winter index indicates that the Minho region is a part of the North Atlantic climate dynamics and demonstrates that the foraminiferal record from Caminha high marsh may be applied in high-resolution studies of SW Europe climate evolution.</p> <div class="credits"> <p class="dwt_author">Fatela, Francisco; Moreno, João; Leorri, Eduardo; Corbett, Reide</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">123</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014BGeo...11.5181B"> <span id="translatedtitle">Land surface phenological response to <span class="hlt">decadal</span> climate <span class="hlt">variability</span> across Australia using satellite remote sensing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Land surface phenological cycles of vegetation greening and browning are influenced by <span class="hlt">variability</span> in climatic forcing. Quantitative spatial information on phenological cycles and their <span class="hlt">variability</span> is important for agricultural applications, wildfire fuel accumulation, land management, land surface modeling, and climate change studies. Most phenology studies have focused on temperature-driven Northern Hemisphere systems, where phenology shows annually recurring patterns. However, precipitation-driven non-annual phenology of arid and semi-arid systems (i.e., drylands) received much less attention, despite the fact that they cover more than 30% of the global land surface. Here, we focused on Australia, a continent with one of the most <span class="hlt">variable</span> rainfall climates in the world and vast areas of dryland systems, where a detailed phenological investigation and a characterization of the relationship between phenology and climate <span class="hlt">variability</span> are missing. To fill this knowledge gap, we developed an algorithm to characterize phenological cycles, and analyzed geographic and climate-driven <span class="hlt">variability</span> in phenology from 2000 to 2013, which included extreme drought and wet years. We linked derived phenological metrics to rainfall and the Southern Oscillation Index (SOI). We conducted a continent-wide investigation and a more detailed investigation over the Murray-Darling Basin (MDB), the primary agricultural area and largest river catchment of Australia. Results showed high inter- and intra-annual <span class="hlt">variability</span> in phenological cycles across Australia. The peak of phenological cycles occurred not only during the austral summer, but also at any time of the year, and their timing varied by more than a month in the interior of the continent. The magnitude of the phenological cycle peak and the integrated greenness were most significantly correlated with monthly SOI within the preceding 12 months. Correlation patterns occurred primarily over northeastern Australia and within the MDB, predominantly over natural land cover and particularly in floodplain and wetland areas. Integrated greenness of the phenological cycles (surrogate of vegetation productivity) showed positive anomalies of more than 2 standard deviations over most of eastern Australia in 2009-2010, which coincided with the transition from the El Niño-induced <span class="hlt">decadal</span> droughts to flooding caused by La Niña.</p> <div class="credits"> <p class="dwt_author">Broich, M.; Huete, A.; Tulbure, M. G.; Ma, X.; Xin, Q.; Paget, M.; Restrepo-Coupe, N.; Davies, K.; Devadas, R.; Held, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">124</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://iprc.soest.hawaii.edu/~xie/mode-jc11.pdf"> <span id="translatedtitle">Dynamical Role of Mode Water Ventilation in <span class="hlt">Decadal</span> <span class="hlt">Variability</span> in the Central Subtropical Gyre of the North Pacific*</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Dynamical Role of Mode Water Ventilation in <span class="hlt">Decadal</span> <span class="hlt">Variability</span> in the Central Subtropical Gyre and weakening of the STCC because of var- iations in mode water ventilation. The changes in mode water can are characteristic of changes in mode water ventilation. Indeed, this natural mode of STCC <span class="hlt">variability</span> is excited</p> <div class="credits"> <p class="dwt_author">Xie, Shang-Ping</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">125</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..1511974S"> <span id="translatedtitle">A model data comparison of different classes of LSW and interannual to <span class="hlt">decadal</span> <span class="hlt">variability</span> in a FESOM model setup</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The climate in the Atlantic region is essentially influenced by the Atlantic meridional overturning circulation (AMOC) which carries warm waters into northern latitudes and returns cold deep water southward across the equator. In the Labrador Sea basin a major component of the cold limb of the Atlantic meridional overturning circulation (AMOC) is formed. The intermediate water mass that is part of this deep convection process is the Labrador Sea Water (LSW) which can be separated into two different classes: the deep LSW (dLSW) and the less dense upper LSW (uLSW). Both LSW modes are formed by convection, accompanied by a strong surface cooling during winter conditions, which leads to an increase in the near-surface density and to an unstable stratification and a homogenization of the water column. In this study we simulated the deep-water formation in the Labrador Sea using the Finite-Element Sea-Ice Ocean Model (FESOM) in a global model setup with regional focus on the Labrador Sea and Greenland Sea. We evaluated the capability of the model setup to reproduce a realistic deep water formation in the Labrador Sea by analyzing the modeled Labrador Sea hydrography and we compared the modeled and <span class="hlt">observational</span> derived dLSW and uLSW layer thicknesses for the time interval 1958-2007. It is shown that the model is able to reproduce different phases in the temporal evolution of the potential density, temperature and salinity, which are known in <span class="hlt">observational</span> data. Based on composite maps of the thermal and haline contributions to the surface density flux we can prove that the central Labrador Sea in the model is dominated by the thermal contributions of the surface density flux, while the haline contributions are limited to the branch of the Labrador Sea Boundary Current system, where they are dominated from the haline contributions of sea ice melting and formation. Our model results feature a shielding of the central Labrador Sea from the haline contributions by the Labrador Sea Boundary Current system. Furthermore we investigated modes of interannual to <span class="hlt">decadal</span> <span class="hlt">variability</span> for the period 1958-2004 and attributed the general <span class="hlt">variability</span> in the model to the atmospheric forcing and to internal modes of the ocean system. Based on a North Atlantic Deep Water (NADW) index defined for a normal and random forced FESOM run, where the interannual to <span class="hlt">decadal</span> atmospheric <span class="hlt">variability</span> in the random forced run is replaced by white noise, we identify modes of interannual to quasi-<span class="hlt">decadal</span> <span class="hlt">variability</span> of 7yr and 14yr, respectively. The origin of the 14yr <span class="hlt">variability</span> is attributed to the atmospheric forcing, while the 7yr <span class="hlt">variability</span> is linked to internal modes of the ocean. To further isolate the horizontal, but also the vertical <span class="hlt">variability</span> in the model, we apply a principal oscillation pattern analysis in a three dimensional context. Two exceptional stable interannual modes are captured by the POP analysis and their <span class="hlt">variability</span> is attributed to a propagating Rossby wave structure.</p> <div class="credits"> <p class="dwt_author">Scholz, Patrick; Lohmann, Gerrit; Ionita, Monica; Kieke, Dagmar; Rhein, Monika</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">126</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015JGRC..120..201Y"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">variability</span> of the Pacific Subtropical Cells and its relevance to the sea surface height in the western tropical Pacific during recent <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">variability</span> of the Pacific Subtropical Cells (STCs) and associated sea surface height (SSH) in the western tropical Pacific during recent <span class="hlt">decades</span> are examined by using an historical OGCM simulation. The model represents <span class="hlt">decadal</span> variations of the STCs concurrent with tropical Pacific thermal anomalies: the eastern tropical Pacific is warmer when the STCs are weaker and cooler when they are stronger. The spatial patterns of the SSH in the western tropical Pacific show different features, depending on events associated with <span class="hlt">decadal</span> <span class="hlt">variability</span>. During the warm phase (1977-1987), the SSH anomalies exhibit deviations from a meridionally symmetric distribution, with weakly positive (strongly negative) anomalies in the western tropical North (South) Pacific. Analysis of the heat budget in the upper tropical Pacific indicates that the termination of the warm phase around 1985 results from a poleward heat transport anomaly that is induced by a horizontal gyre associated with the SSH anomalies. During the cold phase (1996-2006), in contrast, the SSH anomalies are nearly meridionally symmetric, with positive anomalies in both hemispheres. Enhanced easterly wind anomalies contribute to the development of the cold phase after the late 1990s.</p> <div class="credits"> <p class="dwt_author">Yamanaka, Goro; Tsujino, Hiroyuki; Nakano, Hideyuki; Hirabara, Mikitoshi</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">127</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUFM.C41D0355J"> <span id="translatedtitle"><span class="hlt">Variability</span> of the Marine Ecosystem in Response to Climate Changes in the Southeastern Bering Sea Midshelf During the Last <span class="hlt">Decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The climate trends of reducing ice cover and rising temperature in the southeastern Bering Sea have profound impacts on the lower tropic level production and fishery production. To address the issue, a multi-<span class="hlt">decade</span> modeling of the lower trophic level production was conducted using a vertically 1-D coupled ice-ocean ecosystem model that includes both pelagic (Jin et al., 2006a) and sea ice algal components (Jin et al., 2006b). The model was forced by NCEP reanalysis data. Model results were validated with the following <span class="hlt">observations</span>: 1) temperature, salinity, fluorometer data at 12m, 24m and 44m at NOAA/PMEL mooring from 1995-2004; 2) daily SeaWiFS chl a data (1997-2005). Interannual <span class="hlt">variability</span> of the primary production was analyzed and statistical relationship against regional climate index and fisheries index were sought.</p> <div class="credits"> <p class="dwt_author">Jin, M.; Deal, C.; Wang, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">128</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70100468"> <span id="translatedtitle"><span class="hlt">Decadal</span> surface water quality trends under <span class="hlt">variable</span> climate, land use, and hydrogeochemical setting in Iowa, USA</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Understanding how nitrogen fluxes respond to changes in agriculture and climate is important for improving water quality. In the midwestern United States, expansion of corn cropping for ethanol production led to increasing N application rates in the 2000s during a period of extreme <span class="hlt">variability</span> of annual precipitation. To examine the effects of these changes, surface water quality was analyzed in 10 major Iowa Rivers. Several <span class="hlt">decades</span> of concentration and flow data were analyzed with a statistical method that provides internally consistent estimates of the concentration history and reveals flow-normalized trends that are independent of year-to-year streamflow variations. Flow-normalized concentrations of nitrate+nitrite-N decreased from 2000 to 2012 in all basins. To evaluate effects of annual discharge and N loading on these trends, multiple conceptual models were developed and calibrated to flow-weighted annual concentrations. The recent declining concentration trends can be attributed to both very high and very low discharge in the 2000s and to the long (e.g., 8 year) subsurface residence times in some basins. Dilution of N and depletion of stored N occurs in years with high discharge. Reduced N transport and increased N storage occurs in low-discharge years. Central Iowa basins showed the greatest reduction in flow-normalized concentrations, likely because of smaller storage volumes and shorter residence times. Effects of land-use changes on the water quality of major Iowa Rivers may not be noticeable for years or <span class="hlt">decades</span> in peripheral basins of Iowa, and may be obscured in the central basins where extreme flows strongly affect annual concentration trends.</p> <div class="credits"> <p class="dwt_author">Green, Christopher T.; Bekins, Barbara A.; Kalkhoff, Stephen J.; Hirsch, Robert M.; Liao, Lixia; Barnes, Kimberlee K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">129</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014WRR....50.2425G"> <span id="translatedtitle"><span class="hlt">Decadal</span> surface water quality trends under <span class="hlt">variable</span> climate, land use, and hydrogeochemical setting in Iowa, USA</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Understanding how nitrogen fluxes respond to changes in agriculture and climate is important for improving water quality. In the midwestern United States, expansion of corn cropping for ethanol production led to increasing N application rates in the 2000s during a period of extreme <span class="hlt">variability</span> of annual precipitation. To examine the effects of these changes, surface water quality was analyzed in 10 major Iowa Rivers. Several <span class="hlt">decades</span> of concentration and flow data were analyzed with a statistical method that provides internally consistent estimates of the concentration history and reveals flow-normalized trends that are independent of year-to-year streamflow variations. Flow-normalized concentrations of nitrate+nitrite-N decreased from 2000 to 2012 in all basins. To evaluate effects of annual discharge and N loading on these trends, multiple conceptual models were developed and calibrated to flow-weighted annual concentrations. The recent declining concentration trends can be attributed to both very high and very low discharge in the 2000s and to the long (e.g., 8 year) subsurface residence times in some basins. Dilution of N and depletion of stored N occurs in years with high discharge. Reduced N transport and increased N storage occurs in low-discharge years. Central Iowa basins showed the greatest reduction in flow-normalized concentrations, likely because of smaller storage volumes and shorter residence times. Effects of land-use changes on the water quality of major Iowa Rivers may not be noticeable for years or <span class="hlt">decades</span> in peripheral basins of Iowa, and may be obscured in the central basins where extreme flows strongly affect annual concentration trends.</p> <div class="credits"> <p class="dwt_author">Green, Christopher T.; Bekins, Barbara A.; Kalkhoff, Stephen J.; Hirsch, Robert M.; Liao, Lixia; Barnes, Kimberlee K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-03-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">130</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20000112946&hterms=comparing+middle&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcomparing%2Bmiddle"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">Variability</span> and Temperature Trends in the Middle Atmosphere From Historical Rocketsonde Data</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary"><span class="hlt">Observational</span> studies were performed using historical rocketsonde data to investigate long-term temperature trends, solar-cycle variations, and interactions between tropical and extratropical latitudes in the middle atmosphere. Evidence from tropical, subtropical, and midlatitude North American rocketsonde stations indicated a consistent downward trend over 25 years, with a solar cycle component superposed. The trend is about -1.4 to -2.0 K per <span class="hlt">decade</span> and the amplitude of the <span class="hlt">decadal</span> oscillation is about 1.1 K. Prior to trend derivation it was necessary for us to correct temperatures for aerodynamic heating in the early years. The empirically derived correction profile agrees well with a theoretical profile of Krumins and Lyons. A study was also performed of the correlation between equatorial winds and north polar temperatures in winter, showing that the entire stratospheric wind profile near the equator -- including the quasi-biennial oscillation (QBO) and stratopause semiannual oscillation (SAO) -- is important to the extratropical flow, not merely the QBO component as previously thought. A strong correlation was discovered between winter polar temperatures and equatorial winds in the upper stratosphere during the preceding September, suggesting a role for the second cycle of the SAO.</p> <div class="credits"> <p class="dwt_author">Dunkerton, Timothy J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">131</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/17354457"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">variability</span> in growth of the Caribbean spiny lobster Panulirus argus (Decapoda: Paniluridae) in Cuban waters.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Annual von Bertalanffy growth parameters of the Caribbean spiny lobster (Panulirus argus) in Cuban waters were estimated from a long term study (40 years) by length-based methods ELEFAN and the new version of SLCA. Data of around 800 000 lobsters (with carapace length ranging 14 to 199mm) were randomly sampled in artificial shelters (a non selective fishing gear very common in the lobster fishery), through the field monitory program established for this species since 1963 in 14 localities of southwestern Cuban shelf. The software ELEFAN showed problems to converge in an optimal combination of the instantaneous growth coefficient (K) and the asymptotic length (Linfinity) of the von Bertalanffy equation, whereas the new SLCA software produced value estimates of K between 0.20 and 0.27 year(-1) and values of Linfinity between 177 and 190 mm carapace length, all within the range reported in the literature. The standardized anomalies of both parameters showed the presence of cycles along the analyzed time series. <span class="hlt">Decadal</span> <span class="hlt">variability</span> in growth parameters was revealed through the spectral analysis indicating cycles of 16 and 20 years for K and of 16 years for Linfinity. The incidence of some factors such as biomass and temperature that modulate growth in this crustacean was explored, using a nonlinear multiple regression model. These combined factors explained 33% and 69% of the <span class="hlt">variability</span> of K and Linfinity respectively. The growth coefficient appeared to be maximum with annual mean sea surface temperature of 28. 1 degrees C and the largest Linfinity is reached at a annual men biomass level of 23,000 t. These results should be the basis to understand the Cuban lobster population dynamics. PMID:17354457</p> <div class="credits"> <p class="dwt_author">de León, Maria Estela; Martínez, Juana López; Cota, Daniel Lluch; Vázquez, Sergio Hernández; Rafael, Puga</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">132</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56458390"> <span id="translatedtitle">An overview of Pacific <span class="hlt">Decadal</span> (climate) <span class="hlt">Variability</span> impacts on hydroclimate and water resources management in the western US</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Hydroclimate variations at <span class="hlt">decadal</span> to interdecadal time scales have proven to be especially problematic for ecosystems and societies by causing multi-year periods of abundance or scarcity in key natural resources. A review of 20th century Pacific <span class="hlt">Decadal</span> climate <span class="hlt">variability</span> (PDV) impacts on the hydroclimate of North America highlights watersheds that have been especially sensitive to periods of multi-year abundance and</p> <div class="credits"> <p class="dwt_author">N. J. Mantua</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">133</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015ClDy..tmp...62F"> <span id="translatedtitle"><span class="hlt">Observed</span> and simulated inter-<span class="hlt">decadal</span> changes in the structure of Southern Hemisphere large-scale circulation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Several studies have identified that, in the mid-1970s to early 1980s, a major shift occurred in the structure of the large-scale circulation in both hemispheres. This work employs the CSIRO Mk3L general circulation model in ensemble simulations with <span class="hlt">observed</span> sea surface temperatures (SSTs) and historical time-evolving carbon dioxide (CO2) concentrations to investigate the inter-<span class="hlt">decadal</span> changes found <span class="hlt">observationally</span> in the jet streams, temperature, Hadley circulation, mean sea level pressure and precipitation. First, the performance of the model in simulating these changes for the mean July climate fields of 1949-1968 and 1975-1994, in comparison with the corresponding <span class="hlt">observations</span> (NCEP/NCAR Reanalysis I and the Twentieth Century Reanalysis V2), is investigated. We find that the model is quite skilful in reproducing the broad features of the important inter-<span class="hlt">decadal</span> changes that occurred in the mid-1970s. The model simulations and the NCEP/NCAR and twentieth century reanalyses agree in the eastern hemisphere; whereas in the western hemisphere the reanalyses show differences, and the simulations combine aspects of these two datasets. The role of the direct radiative forcing due to CO2 in driving the inter-<span class="hlt">decadal</span> changes is also examined. Results indicate that, in comparison with the indirect effect of CO2 carried by the changing SSTs, there is little additional impact of the direct radiative forcing due to CO2 on the changes in the latter period. However, our simulations with fixed CO2 concentration have shown clearly that the atmospheric simulations with historical time-evolving CO2 concentrations are more skilful in reproducing the inter-<span class="hlt">decadal</span> changes. The sensitivity of the ensemble results to employing the same or different time evolving sea ice boundary conditions in the ensemble members is also studied. The contributions of internal and external <span class="hlt">variability</span> are discussed.</p> <div class="credits"> <p class="dwt_author">Freitas, Ana C. V.; Frederiksen, Jorgen S.; Whelan, Jennifer; O'Kane, Terence J.; Ambrizzi, Tércio</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-02-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">134</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950047289&hterms=spatial+variability+patterns&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dspatial%2Bvariability%2Bpatterns"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">variability</span> of the Tropical Atlantic Ocean Surface Temperature in shipboard measurements and in a Global Ocean-Atmosphere model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Sea surface temperature (SST) <span class="hlt">variability</span> was investigated in a 200-yr integration of a global model of the coupled oceanic and atmospheric general circulations developed at the Geophysical Fluid Dynamics Laboratory (GFDL). The second 100 yr of SST in the coupled model's tropical Atlantic region were analyzed with a variety of techniques. Analyses of SST time series, averaged over approximately the same subregions as the Global Ocean Surface Temperature Atlas (GOSTA) time series, showed that the GFDL SST anomalies also undergo pronounced quasi-oscillatory <span class="hlt">decadal</span> and multidecadal <span class="hlt">variability</span> but at somewhat shorter timescales than the GOSTA SST anomalies. Further analyses of the horizontal structures of the <span class="hlt">decadal</span> timescale <span class="hlt">variability</span> in the GFDL coupled model showed the existence of two types of <span class="hlt">variability</span> in general agreement with results of the GOSTA SST time series analyses. One type, characterized by timescales between 8 and 11 yr, has high spatial coherence within each hemisphere but not between the two hemispheres of the tropical Atlantic. A second type, characterized by timescales between 12 and 20 yr, has high spatial coherence between the two hemispheres. The second type of <span class="hlt">variability</span> is considerably weaker than the first. As in the GOSTA time series, the multidecadal <span class="hlt">variability</span> in the GFDL SST time series has approximately opposite phases between the tropical North and South Atlantic Oceans. Empirical orthogonal function analyses of the tropical Atlantic SST anomalies revealed a north-south bipolar pattern as the dominant pattern of <span class="hlt">decadal</span> <span class="hlt">variability</span>. It is suggested that the bipolar pattern can be interpreted as <span class="hlt">decadal</span> <span class="hlt">variability</span> of the interhemispheric gradient of SST anomalies. The <span class="hlt">decadal</span> and multidecadal timescale <span class="hlt">variability</span> of the tropical Atlantic SST, both in the actual and in the GFDL model, stands out significantly above the background 'red noise' and is coherent within each of the time series, suggesting that specific sets of processes may be responsible for the choice of the <span class="hlt">decadal</span> and multidecadal timescales. Finally, it must be emphasized that the GFDL coupled ocean-atmosphere model generates the <span class="hlt">decadal</span> and multidecadal timescale <span class="hlt">variability</span> without any externally applied force, solar or lunar, at those timescales.</p> <div class="credits"> <p class="dwt_author">Mehta, Vikram M.; Delworth, Thomas</p> <p class="dwt_publisher"></p> <p class="publishDate">1995-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">135</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFMOS42B..01R"> <span id="translatedtitle"><span class="hlt">Variability</span> in a Multi-<span class="hlt">Decadal</span> Record of Ocean Acidification in Surface Waters of the U.S. Northeast Shelf</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Multiple shelf-wide surveys of the Northeast Shelf of the United States, from the Gulf of Maine through the Mid-Atlantic Bight, were conducted as part of the NOAA Marine Resources Monitoring, Assessment, and Prediction Program (MARMAP) and the Northeast Monitoring Program (NEMP). <span class="hlt">Observations</span> including pH, total alkalinity, temperature, and salinity were collected from 1973-1984. These historical data were compared to recent data collected as part of a joint NASA/NOAA project (CliVEC) as part of the NOAA Ocean Acidification Program. A preliminary comparison of the historical surface waters suggests that interannual <span class="hlt">variability</span> in the carbonate system is approximately equal in magnitude to the expected multi-<span class="hlt">decadal</span> changes. Where geographically comparable data exist for the MARMAP era and recent surveys, changes appear to be dominated by varying water masses, however salinity normalized DIC in the Mid-Atlantic Bight appears to have increased proportional to other published global averages. Ongoing studies of carbonate chemistry in the region will benefit from the availability of this retrospective baseline of the carbonate system and a greater understanding of the seasonal, interannual, and interdecadal <span class="hlt">variability</span>. Determining the proximal causes of differences between acidification on the Northeast Shelf and the global average is a necessary component of future ecological modeling studies and regional management in this biologically productive and economically valuable region.</p> <div class="credits"> <p class="dwt_author">Rebuck, N. D.; Hare, J. A.; Mulholland, M. R.; Bernhardt, P. W.; Staryk, C. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">136</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110023540&hterms=Arctic+Ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2522Arctic%2BOcean%2522"> <span id="translatedtitle">Interannual to <span class="hlt">Decadal</span> <span class="hlt">Variability</span> of Atlantic Water in the Nordic and Adjacent Seas</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Warm salty Atlantic Water is the main source water for the Arctic Ocean and thus plays an important role in the mass and heat budget of the Arctic. This study explores interannual to <span class="hlt">decadal</span> <span class="hlt">variability</span> of Atlantic Water properties in the Nordic Seas area where Atlantic Water enters the Arctic, based on a reexamination of the historical hydrographic record for the years 1950-2009, obtained by combining multiple data sets. The analysis shows a succession of four multi-year warm events where temperature anomalies at 100m depth exceed 0.4oC, and three cold events. Three of the four warm events lasted 3-4 years, while the fourth began in 1999 and persists at least through 2009. This most recent warm event is anomalous in other ways as well, being the strongest, having the broadest geographic extent, being surface-intensified, and occurring under exceptional meteorological conditions. Three of the four warm events were accompanied by elevated salinities consistent with enhanced ocean transport into the Nordic Seas, with the exception of the event spanning July 1989-July 1993. Of the three cold events, two lasted for four years, while the third lasted for nearly 14 years. Two of the three cold events are associated with reduced salinities, but the cold event of the 1960s had elevated salinities. The relationship of these events to meteorological conditions is examined. The results show that local surface heat flux variations act in some cases to reinforce the anomalies, but are too weak to be the sole cause.</p> <div class="credits"> <p class="dwt_author">Carton, James A.; Chepurin, Gennady A.; Reagan, James; Haekkinen, Sirpa</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">137</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3286343"> <span id="translatedtitle">Morbidity and mortality in common <span class="hlt">variable</span> immune deficiency over 4 <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">The demographics, immunologic parameters, medical complications, and mortality statistics from 473 subjects with common <span class="hlt">variable</span> immune deficiency followed over 4 <span class="hlt">decades</span> in New York were analyzed. Median immunoglobulin levels were IgG, 246 mg/dL; IgA, 8 mg/dL; and IgM, 21 mg/dL; 22.6% had an IgG less than 100 mg/dL. Males were diagnosed earlier (median age, 30 years) than females (median age, 33.5 years; P = .004). Ninety-four percent of patients had a history of infections; 68% also had noninfectious complications: hematologic or organ-specific autoimmunity, 28.6%; chronic lung disease, 28.5%; bronchiectasis, 11.2%; gastrointestinal inflammatory disease, 15.4%; malabsorption, 5.9%; granulomatous disease, 9.7%; liver diseases and hepatitis, 9.1%; lymphoma, 8.2%; or other cancers, 7.0%. Females had higher baseline serum IgM (P = .009) and were more likely to develop lymphoma (P = .04); 19.6% of patients died, a significantly shorter survival than age- and sex-matched population controls (P < .0001). Reduced survival was associated with age at diagnosis, lower baseline IgG, higher IgM, and fewer peripheral B cells. The risk of death was 11 times higher for patients with noninfectious complications (hazard ratio = 10.95; P < .0001). Mortality was associated with lymphoma, any form of hepatitis, functional or structural lung impairment, and gastrointestinal disease with or without malabsorption, but not with bronchiectasis, autoimmunity, other cancers, granulomatous disease, or previous splenectomy. PMID:22180439</p> <div class="credits"> <p class="dwt_author">Resnick, Elena S.; Moshier, Erin L.; Godbold, James H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">138</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AGUFM.B11G..04P"> <span id="translatedtitle">Wetland inventory and <span class="hlt">variability</span> over the last two <span class="hlt">decades</span> at a global scale</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Remote sensing techniques employing visible, infrared, and microwave <span class="hlt">observations</span> offer varying success in estimating wetlands and inundation extent and in monitoring their natural and anthropogenic variations. Low spatial resolution (e.g., 30 km) limits detection to large wetlands but has the advantage of frequent coverage. High spatial resolution (e.g., 100 m), while providing more environmental information, suffers from poor temporal resolution, with <span class="hlt">observations</span> for just high/low water or warm/cold seasons. Most existing wetland data sets are limited to a few regions, for specific times in the year. The only global inventories of wetland dynamics over a long period of time is derived from a remote-sensing technique employing a suite of complementary satellite <span class="hlt">observations</span>: it uses passive microwave land-surface microwave emissivities, scatterometer responses, and visible and near infrared reflectances. Combining <span class="hlt">observations</span> from different instruments makes it possible to capitalize on their complementary strengths, and to extract maximum information about inundation characteristics. The technique is globally applicable without any tuning for particular environments. The satellite data are used to calculate monthly-mean inundated fractions of equal-area grid cells (0.25°x0.25° at the equator), taking into account the contribution of vegetation to the passive microwave signal (Prigent et al., 2001, 2007). Several adjustments to the initial technique have been applied to account for changes in satellite instruments (Papa et al., 2010). The resulting data set now covers 1993-2008 and has been carefully evaluated. We will present the inter-annual <span class="hlt">variability</span> of the water surface extents under different environments, and relate these variations to other hydrological <span class="hlt">variables</span> such as river height, precipitation, water runoff, or Grace data. Natural wetlands are the world's largest methane source and dominate the inter-annual <span class="hlt">variability</span> of atmospheric methane concentrations, with up to 90% of the global methane flux anomalies related to variations in the wetland extent from some estimation. Our data set quantifying inundation dynamics throughout the world's natural wetlands provides a unique opportunity to reduce uncertainties in the role of natural wetlands in the inter-annual <span class="hlt">variability</span> of the growth rate of atmospheric methane. Papa, F., C. Prigent, C. Jimenez, F. Aires, and W. B. Rossow, Interannual <span class="hlt">variability</span> of surface water extent at global scale, 1993-2004, JGR, 115, D12111, doi:10.1029/2009JD012674, 2010. Prigent, C., F. Papa, F. Aires, W. B. Rossow, and E. Matthews, Global inundation dynamics inferred from multiple satellite <span class="hlt">observations</span>, 1993-2000, JGR, 112, D12107, doi:10.1029/2006JD007847, 2007. Prigent, C., E. Matthews, F. Aires, and W. B. Rossow, Remote sensing of global wetland dynamics with multiple satellite data sets, GRL, 28 , 4631-4634, 2001.</p> <div class="credits"> <p class="dwt_author">Prigent, C.; Papa, F.; Aires, F.; Rossow, W. B.; Matthews, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">139</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014QSRv..105...86B"> <span id="translatedtitle">High resolution sedimentary record of dinoflagellate cysts reflects <span class="hlt">decadal</span> <span class="hlt">variability</span> and 20th century warming in the Santa Barbara Basin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present a continuous record of dinoflagellate cysts from a core of laminated sediments collected in the Santa Barbara Basin (SBB), off Southern California. The core spans the last ?260 years and is analysed at biennial (two-year) resolution. Variations in dinoflagellate cyst assemblages are compared with 20th century historical changes, and are used to examine changes in primary productivity and species composition, which are bound to the <span class="hlt">variability</span> in upwelling and sea-surface temperature (SST) in the region. Cysts produced by heterotrophic dinoflagellates dominate the assemblages. In particular, Brigantedinium spp. (on average 64.2% of the assemblages) are commonly associated with high levels of primary productivity, typically <span class="hlt">observed</span> under active upwelling conditions, when nutrient supply is higher. Other heterotrophic taxa such as cysts of Protoperidinium americanum, Protoperidinium fukuyoi, Protoperidinium minutum and Archaeperidinium saanichi, all Echinidinium species, Quinquecuspis concreta and Selenopemphix undulata are more abundant in the early part of the record (?1750s-1870s). These taxa are generally associated with high primary productivity and are <span class="hlt">observed</span> predominantly during intervals marked by relatively <span class="hlt">variable</span> conditions of SST, stratification and nutrient loading. The 20th century is marked by an increase in several species of autotrophic affinity, primarily Lingulodinium machaerophorum and Spiniferites ramosus. In recent surface sediments from the region, these species are more abundant in the Southern California Bight, and they are associated with conditions of relaxed upwelling in the SBB (typically <span class="hlt">observed</span> during summer and fall), when SST is higher and nutrient supply is moderate. Their increasing concentrations since the early 20th century reflect warmer SST and possibly stronger stratification during the warmest season. Taken together, the changes in cyst assemblages provide further evidence that persistently warmer conditions in the SBB began affecting marine populations by the late 1920s. <span class="hlt">Decadal</span>-scale variations in primary productivity are encoded in the heterotrophic dinoflagellate cyst record, with higher (lower) concentrations of heterotrophic taxa occurring during "cool" ("warm") phases of the Pacific <span class="hlt">Decadal</span> Oscillation (PDO) index. Wavelet analysis of heterotrophic taxa concentrations suggests a weaker influence of the PDO on biota of the region during the 19th century.</p> <div class="credits"> <p class="dwt_author">Bringué, Manuel; Pospelova, Vera; Field, David B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">140</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JSR....86...97T"> <span id="translatedtitle">Impact of the river nutrient load <span class="hlt">variability</span> on the North Aegean ecosystem functioning over the last <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The impact of river load <span class="hlt">variability</span> on the North Aegean ecosystem functioning over the last <span class="hlt">decades</span> (1980-2000) was investigated by means of a coupled hydrodynamic/biogeochemical model simulation. Model results were validated against available SeaWiFS Chl-a and in situ data. The simulated food web was found dominated by small cells, in agreement with <span class="hlt">observations</span>, with most of the carbon channelled through the microbial loop. Diatoms and dinoflagellates presented a higher relative abundance in the more productive coastal areas. The increased phosphate river loads in the early 80s resulted in nitrogen and silicate deficiency in coastal, river-influenced regions. Primary production presented a decreasing trend for most areas. During periods of increased phosphate/nitrate inputs, silicate deficiency resulted in a relative decrease of diatoms, triggering an increase of dinoflagellates. Such an increase was simulated in the late 90s in the Thermaikos Gulf, in agreement with the <span class="hlt">observed</span> increased occurrence of Harmful Algal Blooms. Microzooplankton was found to closely follow the relative increase of dinoflagellates under higher nutrient availability, showing a faster response than mesozooplankton. Sensitivity simulations with varying nutrient river inputs revealed a linear response of net primary production and plankton biomass. A stronger effect of river inputs was simulated in the enclosed Thermaikos Gulf, in terms of productivity and plankton composition, showing a significant increase of dinoflagellates relative abundance under increased nutrient loads.</p> <div class="credits"> <p class="dwt_author">Tsiaras, K. P.; Petihakis, G.; Kourafalou, V. H.; Triantafyllou, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-02-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_6");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return 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id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_7");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a style="font-weight: bold;">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_9");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">141</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1982iue..prop.1095F"> <span id="translatedtitle"><span class="hlt">Observations</span> of <span class="hlt">Variable</span> & Proto-Planrtary Nebulae</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The scientific objective of the proposed <span class="hlt">observing</span> program is to use the IUE for obtaining ultraviolet spectra of <span class="hlt">variable</span> and proto-planetary nebulae that have in the past shown dramatic changes in their ultraviolet characteristics. In particular, the so-called "proto-planetary" nebulae V 1016 Cyg, HM Sge and HBV 475 (=V 1329 Cyg) were studied during the forth year and revealed changes in emission line fluxes, line profiles, emission line ratios, electron densities and level of excitation and ionization. These changes offer a rare opportunity to follow the evolutionary pattern for this type of object. Longer term changes in emission line fluxes and profiles are suspected for IC 4997 and NGC 6905. A high dispersion spectrogram is required for NGC 6905 in the LWR range to resolve some ambiguities not resolved in the previous low dispersion <span class="hlt">observations</span>.</p> <div class="credits"> <p class="dwt_author">Feibelman, Walter A.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">142</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002AGUFMPP62A0316M"> <span id="translatedtitle"><span class="hlt">Decadal</span>-Scale Tropical North Atlantic Climate <span class="hlt">Variability</span> Recorded in Slow Growing Cape Verde Corals</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The <span class="hlt">decadal</span> to century scale climate <span class="hlt">variability</span> of the tropical North Atlantic has major implications for both neighboring coastal and inland areas. Changes in patterns of sea surface temperature (SST) and SST anomalies (SSTA) in the tropical North Atlantic are known to affect rainfall in Florida, South America, and sub-Saharan Africa, as well as the number of major hurricanes formed in the Atlantic. Because of the significance of these connections, it is important to further increase our predictive capacity for the recognition of trends and cycles in tropical North Atlantic SST and SSTA. Located at 15° N latitude off the west coast of sub-Saharan Africa, the Cape Verde Islands are an ideal geographic location to search for records of the Tropical North Atlantic Index (TNA). Such patterns are present in proxy indicators of climate (O, C, Sr/Ca and Mg/Ca) recorded in the skeletons of slow growing corals, such as Siderastrea radians, found in Cape Verde (growth rate = 1-2 mm/yr). These corals represent an archive for SST and SSTA records that exceed the instrumental period of the eastern tropical North Atlantic. We cored corals from several different locations within the Cape Verde archipelago and analyzed them for stable isotopes (?13C and ?18O) and minor elements (Sr, Mg, and Ba). The ?18O signal present in these corals shows a distinct relationship to the TNA over the better part of the last 100 years. In addition, the ?18O record in several of these corals also records the onset of the latest Sahel (11°-18° N in Africa) drought which began in 1970. The Sr/Ca and Mg/Ca records of these corals indicate a slight warming of the waters around Cape Verde during the last 100 years, as well as accurately recording the El Niño events of 1982-83 and 1997-98. The correlations present between the records in these corals and the known instrumental record for the eastern tropical North Atlantic suggests that the fluctuations recorded in the proxy indicators may be accurately used as a tool to study both the intensity and duration of SST and SSTA cycles as far back as the 1880's.</p> <div class="credits"> <p class="dwt_author">Moses, C. S.; Swart, P. K.; Dodge, R. E.; Helmle, K. P.; Thorrold, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">143</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2002ClDy...20..175M"> <span id="translatedtitle">Atmospheric simulations using a GCM with simplified physical parametrizations. I: model climatology and <span class="hlt">variability</span> in multi-<span class="hlt">decadal</span> experiments</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This work describes the formulation and climatology of an atmospheric general circulation model (GCM) of intermediate complexity, based on a spectral primitive-equation dynamical core and a set of simplified physical parametrization schemes. The parametrization package has been specially designed to work in models with just a few vertical levels, and is based on the same physical principles adopted in the schemes of state-of-the art GCMs. The parametrized processes include large-scale condensation, convection, clouds, short-wave and long-wave radiation, surface fluxes and vertical diffusion. In the current configuration, the model (nicknamed SPEEDY, from Simplified Parametrizations, primitivE-Equation DYnamics") has five vertical levels and a spectral truncation at total wave number 30 (T30L5). The top vertical level (crudely) represents the stratosphere, the bottom one the planetary boundary layer. Computationally, SPEEDY requires (at least) one order of magnitude less CPU time than a state-of-the-art GCM at the same horizontal resolution, and is therefore suitable for studies of inter-<span class="hlt">decadal</span> or inter-centennial <span class="hlt">variability</span>. Statistics of the model mean state and <span class="hlt">variability</span> are computed from an ensemble of 41-year simulations forced by <span class="hlt">observed</span> sea-surface temperatures in the period 1952-1992. The model mean state is closer to the <span class="hlt">observed</span> climatology during the (boreal) winter than during summer. In winter (i.e. December to February, DJF), the model underestimates the amplitude of the Northern Hemisphere stationary wave pattern, particularly in the European-Atlantic sector. Some aspects of the systematic error of SPEEDY are in fact typical of many GCMs, although the error amplitude is stronger than in state-of-the-art models. On the other hand, the global distribution of precipitation in DJF is quite realistic, and compares well with that of more complex GCMs. In summer (June to August), a strong negative bias in the mid-tropospheric temperature generates a Northern Hemisphere circulation with some springtime characteristics. In particular, the position of the Tropical Convergence Zone in the Indian Ocean remains too far south, leading to a deficient simulation of the monsoon circulation over South Asia. The simulated <span class="hlt">variability</span> during the northern winter is reasonably realistic as far as the spatial distribution is concerned, although some underestimation in the intensity can be found, particularly in the low-frequency range and in the Atlantic sector. The atmospheric response to ENSO events is also weaker than <span class="hlt">observed</span>, although the spatial patterns of the rainfall and geopotential response in the Pacific sector are in phase with their <span class="hlt">observed</span> counterparts. In the Atlantic/Eurasian region, the spatial patterns associated with the interdecadal trends in the simulated and <span class="hlt">observed</span> large-scale circulation show a clear positive correlation, consistent with the hypothesis of a positive ocean-atmosphere feedback on <span class="hlt">decadal</span> time scales.</p> <div class="credits"> <p class="dwt_author">Molteni, F.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">144</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/2141283"> <span id="translatedtitle">Relative effects of multi-<span class="hlt">decadal</span> climatic <span class="hlt">variability</span> and changes in the mean and <span class="hlt">variability</span> of climate due to global warming: future streamflows in Britain</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Climate change impact assessments conventionally assess just the implications of a change in mean climate due to global warming. This paper compares such effects of such changes with those due to natural multi-<span class="hlt">decadal</span> <span class="hlt">variability</span>, and also explores the effects of changing the year-to-year <span class="hlt">variability</span> in climate as well as the mean. It estimates changes in mean monthly flows and a</p> <div class="credits"> <p class="dwt_author">Nigel W Arnell</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">145</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20140013019&hterms=Ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DOcean"> <span id="translatedtitle">North Pacific <span class="hlt">Decadal</span> <span class="hlt">Variability</span> in the GEOS-5 Atmosphere-Ocean Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This study examines the mechanisms of the Pacific <span class="hlt">decadal</span> oscillation (PDO) in the GEOS-5 general circulation model. The model simulates a realistic PDO pattern that is resolved as the first empirical orthogonal function (EOF) of winter sea surface temperature (SST). The simulated PDO is primarily forced by Aleutian low through Ekman transport and surface fluxes, and shows a red spectrum without any preferred periodicity. This differs from the <span class="hlt">observations</span>, which indicate a greater role of El Nino-Southern Oscillation (ENSO) forcing, and likely reflects the too short time scale of the simulated ENSO. The geostrophic transport in response to the Aleutian low is limited to the Kuroshio-Oyashio Extension, and is unlikely the main controlling factor in this model, although it reinforces the Ekman-induced SST anomalies. The delay between the Aleutian low and the PDO is relatively short (1 year) suggesting that the fast Ekman response (rather than Rossby wave propagation) sets the SST pattern immediately following an Aleutian low fluctuation. The atmospheric feedback (response to the SST) is only about 25 of the forcing and never evolves into an Aleutian low completely, instead projecting onto the North Pacific Oscillation (NPO), a meridional dipole in sea level pressure (SLP). The lack of preferred periodicity and weak atmospheric response bothindicate a coupled oscillation is an unlikely mechanism for the PDO in this model. In agreement with recent studies, the NPO is correlated with the North Pacific Gyre Oscillation (NPGO), which is another leading EOF of the North Pacific SST. A possible connection between the PDO and the NPGO is discussed.</p> <div class="credits"> <p class="dwt_author">Achuthavarier, Deepthi; Schubert, Siegfried D.; Vikhliaev, Yury V.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">146</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://cadswes.colorado.edu/sites/default/files/PDF/Theses-PhD/Regonda_PhD2006.pdf"> <span id="translatedtitle">INTRA-ANNUAL TO INTER-<span class="hlt">DECADAL</span> <span class="hlt">VARIABILITY</span> IN THE UPPER COLORADO HYDROCLIMATOLOGY: DIAGNOSIS, FORECASTING AND</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">and climate change; and using this information it develops a statistical forecasting framework which scenarios using paleo reconstructions (tree ring based reconstructions of past streamflows) in conjunction Rajagopalan This research analyzes hydrological <span class="hlt">variability</span> in association with climate <span class="hlt">variability</span></p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">147</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/25001240"> <span id="translatedtitle"><span class="hlt">Observed</span> cold season changes in a Fennoscandian fell area over the past three <span class="hlt">decades</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">We studied trends and <span class="hlt">variability</span> in snow and climate characteristics in 1978-2012 in the Värriötunturit fell area, northern Finland. Cold season changes were examined using long-term <span class="hlt">observational</span> data on snow depths, meteorological data, large-scale climate indices, and reindeer herders' experiences with difficult snow conditions. Snow depths declined, and temperatures increased significantly over the study period, with the largest changes <span class="hlt">observed</span> in October-December and in April. Snow depths decreased particularly in forests at lower altitudes but not in treeless areas at higher altitudes. Interannual <span class="hlt">variability</span> (but not the trends) in snow depths could be partially linked to large-scale climate indices. A majority of difficult reindeer grazing conditions were related to deep snow in the winter or spring. Our <span class="hlt">observations</span> suggest that shortened duration of snow cover may facilitate reindeer grazing, whereas potentially more frequent formation of ice layers and mold growth on pastures in the future is disadvantageous for reindeer husbandry. PMID:25001240</p> <div class="credits"> <p class="dwt_author">Kivinen, Sonja; Rasmus, Sirpa</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">148</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011SerAJ.182...35D"> <span id="translatedtitle">Corrected mu_delta for Stars of Hipparcos Catalogue from Independent Latitude <span class="hlt">Observations</span> over Many <span class="hlt">Decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">During the last century, there were many so-called independent latitude (IL) stations with the <span class="hlt">observations</span> which were included into data of a few international organizations (like Bureau International de l'Heure - BIH, International Polar Motion Service - IPMS) and the Earth rotation programmes for determining the Earth Orientation Parameters - EOP. Because of this, nowadays, there are numerous astrometric ground-based <span class="hlt">observations</span> (made over many <span class="hlt">decades</span>) of some stars included in the Hipparcos Catalogue (ESA 1997). We used these latitude data for the inverse investigations - to improve the proper motions in declination ?_{?} of the mentioned Hipparcos stars. We determined the corrections ??_{?} and investigated agreement of our ?_{?} and those from the catalogues Hipparcos and new Hipparcos (van Leeuwen 2007). To do this we used the latitude variations of 7 stations (Belgrade, Blagoveschtschensk, Irkutsk, Poltava, Pulkovo, Warsaw and Mizusawa), covering different intervals in the period 1904.7 - 1992.0, obtained with 6 visual and 1 floating zenith telescopes (Mizusawa). On the other hand, with regard that about two <span class="hlt">decades</span> have elapsed since the Hipparcos ESA mission <span class="hlt">observations</span> (the epoch of Hipparcos catalogue is 1991.25), the error of apparent places of Hipparcos stars has increased by nearly 20 mas because of proper motion errors. Also, the mission lasted less than four years which was not enough for a sufficient accuracy of proper motions of some stars (such as double or multiple ones). Our method of calculation, and the calculated ?_{?} for the common IL/Hipparcos stars are presented here. We constructed an IL catalogue of 1200 stars: there are 707 stars in the first part (with at least 20 years of IL <span class="hlt">observations</span>) and 493 stars in the second one (less than 20 years). In the case of ?_{&delta}; of IL stars <span class="hlt">observed</span> at some stations (Blagoveschtschensk, Irkutsk, Mizusawa, Poltava and Pulkovo) we find the formal errors less than the corresponding Hipparcos ones and for some of them (stations Blagoveschtschensk and Irkutsk) even less than the new Hipparcos ones.</p> <div class="credits"> <p class="dwt_author">Damljanovic, G.; Milic, I. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">149</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUFMOS23E..05M"> <span id="translatedtitle">An Overview of the Impacts of Pacific <span class="hlt">Decadal</span> Climate <span class="hlt">Variability</span> on Marine Ecosystems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Over the past few <span class="hlt">decades</span> a wealth of evidence has pointed to strong associations between multi-<span class="hlt">decadal</span> climate changes and marine ecosystem changes in the Pacific. The period from the late 1970's through the mid-1990's, for example, saw sustained high productivity for most Pacific salmon at the northern end of their range coinciding with sustained low productivity for Pacific salmon at the southern end of their range. It is now recognized that this "north-south inverse production pattern" for Pacific salmon played out over much of the 20th Century in response to Pacific <span class="hlt">Decadal</span> climate variations. There is abundant direct and indirect evidence for <span class="hlt">decadal</span> scale climate impacts on many other Pacific marine species, including (among others) sardines and anchovies in the Humboldt and California Currents, and pollock and crab in the Bering Sea. In special cases, interdecadal ecosystem changes have been termed "ecosystem regime shifts", wherein evidence points to large-scale ecosystem restructuring at both lower and upper trophic levels. Understanding the mechanisms linking <span class="hlt">decadal</span> variations in climate to ecosystems has proven to be a major challenge, and the lack of understanding poses a serious barrier to predicting ecosystem changes at the time-space scales important to resource managers and the fishing industry.</p> <div class="credits"> <p class="dwt_author">Mantua, N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">150</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFMSH33C..07E"> <span id="translatedtitle">Geomagnetic storms during the last <span class="hlt">decade</span>: Cluster and Double Star <span class="hlt">observations</span> (Invited)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The launch of the Cluster spacecraft almost coincided with one of the largest geomagnetic storm of the last <span class="hlt">decade</span>, well known as the "Bastille Day" storm, on 14-15 July 2000. Planned on 15 July, the launch was aborted a few minutes before due to a thunderstorm that had hit the Baikonour cosmodrome and made a disruption in the communication lines with the rocket. The launch took place the day after, on 16 July 2000. Our US colleagues had warned us about the storm and recommended not to launch on 15 July. Given the facts that (1) Cluster was built to study the effects of space weather and geomagnetic storms and (2) that the Russian launch authorities were not concerned for the Soyuz rocket, it was decided to go ahead with the launch. The launch was fine and, after a second launch less than a month later, the four Cluster spacecraft were put successfully in their 4x19 RE polar orbit. Since then, Cluster has <span class="hlt">observed</span> many geomagnetic storms and could <span class="hlt">observe</span>, for the first time with a constellation of four spacecraft, the dynamics induced in the magnetosphere by coronal mass ejections or interplanetary shocks coming from the Sun. In this talk we will use storms <span class="hlt">observed</span> by Cluster and Double Star in the last <span class="hlt">decade</span> to illustrate how the magnetosphere was affected. We have <span class="hlt">observed</span> large compressions of the magnetosphere, distortions of the polar cusp, acceleration of particles associated with chorus and ULF waves, intensification of the ring current imaged by energetic neutral atom imagers, oxygen outflow from polar regions, and tail current sheet motions.</p> <div class="credits"> <p class="dwt_author">Escoubet, C.; Taylor, M. G.; Masson, A.; Laakso, H. E.; Liu, Z.; Goldstein, M. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">151</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.3910L"> <span id="translatedtitle"><span class="hlt">Observed</span> changes in water temperature and ice dynamics at selected lakes of Russia in the past <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The potential impacts of climate <span class="hlt">variability</span> and change on lake hydrology are complex, especially as lakes are an important freshwater resource. The eight largest lakes of Russia contain about 96% of water resources of all lakes over Russia territory. Lakes Ladoga, Onega, Chudsko-Pskovskoe and Ilmen are the largest fresh water lakes of European territory of Russia. The catchment area of Lake Ladoga includes catchments of two other Lakes - Onega and Ilmen. The world's deepest and oldest Lake Baikal is among the four larget lakes of the Asian part of Russia including Lakes Lakes Khanka, Taimyr and closed brackishwater Lake Chany.Variations in air temperature, precipitation, and other meteorological parameters cause direct changes in the hydrological regime of lakes, such as: water level, thermal characteristics, ice events and ice thickness as well as hydrochemical and hydrobiological regimes and the entire lakes ecosystem. However, the response of the individual lakes and lake basins to these changes will depend on the magnitude and nature of regional climate change including peculiarities of the atmospheric circulation manifestation and the specific geomorphologic characteristics of the lakes. The study was based on the data of ice <span class="hlt">observations</span> on the largest lakes of European Russia (Lakes Ladoga, Onega and Ilmen) and Lakes Baikal, Taimyr and Khanka in the Asian Russia. <span class="hlt">Observation</span> period varies from 40 years for the Lake Taimyr to 118-116 years for Lakes Ladoga and Onega. Temporal trends have been discovered towards changes in the duration of the complete ice cover and maximum ice thickness on the background of a long-term <span class="hlt">variability</span>. All <span class="hlt">observed</span> characteristics of water temperature regime demonstrate the response to changes in air temperature over lakes basins. Mean monthly water temperature increased in Lakes Chany and Baikal by 0.5°C/<span class="hlt">decade</span> and by 0.3°C/<span class="hlt">decade</span> in the mentioned lakes of European part of Russia. Water temperature change directly affects lake ice dynamics. This has important implications for aquatic ecosystems' sustainable development and activities on lakes. Maximal ice cover thickness had the most pronounced response to climate warming in winter time during the last <span class="hlt">decades</span>. All studied lakes exhibited the tendency of reduced ice cover thickness after 1980 by 5-10 cm. The mentioned lakes in the European Russian territory and Lake Baikal show the tendencies to decrease in duration of ice coverage by 10-15 days mainly because of earlier date of ice cover break-up.</p> <div class="credits"> <p class="dwt_author">Lemeshko, Natalia; Eitzinger, Josef; Kubu, Gerhard</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">152</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110012422&hterms=climate+adaptation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dclimate%2Badaptation"> <span id="translatedtitle">CLARREO Cornerstone of the Earth <span class="hlt">Observing</span> System: Measuring <span class="hlt">Decadal</span> Change Through Accurate Emitted Infrared and Reflected Solar Spectra and Radio Occultation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Climate Absolute Radiance and Refractivity Observatory (CLARREO) is one of four Tier 1 missions recommended by the recent NRC <span class="hlt">Decadal</span> Survey report on Earth Science and Applications from Space (NRC, 2007). The CLARREO mission addresses the need to provide accurate, broadly acknowledged climate records that are used to enable validated long-term climate projections that become the foundation for informed decisions on mitigation and adaptation policies that address the effects of climate change on society. The CLARREO mission accomplishes this critical objective through rigorous SI traceable <span class="hlt">decadal</span> change <span class="hlt">observations</span> that are sensitive to many of the key uncertainties in climate radiative forcings, responses, and feedbacks that in turn drive uncertainty in current climate model projections. These same uncertainties also lead to uncertainty in attribution of climate change to anthropogenic forcing. For the first time CLARREO will make highly accurate, global, SI-traceable <span class="hlt">decadal</span> change <span class="hlt">observations</span> sensitive to the most critical, but least understood, climate forcings, responses, and feedbacks. The CLARREO breakthrough is to achieve the required levels of accuracy and traceability to SI standards for a set of <span class="hlt">observations</span> sensitive to a wide range of key <span class="hlt">decadal</span> change <span class="hlt">variables</span>. The required accuracy levels are determined so that climate trend signals can be detected against a background of naturally occurring <span class="hlt">variability</span>. Climate system natural <span class="hlt">variability</span> therefore determines what level of accuracy is overkill, and what level is critical to obtain. In this sense, the CLARREO mission requirements are considered optimal from a science value perspective. The accuracy for <span class="hlt">decadal</span> change traceability to SI standards includes uncertainties associated with instrument calibration, satellite orbit sampling, and analysis methods. Unlike most space missions, the CLARREO requirements are driven not by the instantaneous accuracy of the measurements, but by accuracy in the large time/space scale averages that are key to understanding <span class="hlt">decadal</span> changes.</p> <div class="credits"> <p class="dwt_author">Sandford, Stephen P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">153</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20140011835&hterms=Time&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DTime"> <span id="translatedtitle">Teleconnections, Midlatitude Cyclones and Aegean Sea Turbulent Heat Flux <span class="hlt">Variability</span> on Daily Through <span class="hlt">Decadal</span> Time Scales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We analyze daily wintertime cyclone <span class="hlt">variability</span> in the central and eastern Mediterranean during 1958-2001, and identify four distinct cyclone states, corresponding to the presence or absence of cyclones in each basin. Each cyclone state is associated with wind flows that induce characteristic patterns of cooling via turbulent (sensible and latent) heat fluxes in the eastern Mediterranean basin and Aegean Sea. The relative frequency of occurrence of each state determines the heat loss from the Aegean Sea during that winter, with largest heat losses occurring when there is a storm in the eastern but not central Mediterranean (eNOTc), and the smallest occurring when there is a storm in the central but not eastern Mediterranean (cNOTe). Time series of daily cyclone states for each winter allow us to infer Aegean Sea cooling for winters prior to 1985, the earliest year for which we have daily heat flux <span class="hlt">observations</span>. We show that cyclone states conducive to Aegean Sea convection occurred in 1991/1992 and 1992/1993, the winters during which deep water formation was <span class="hlt">observed</span> in the Aegean Sea, and also during the mid-1970s and the winters of 1963/1964 and 1968/1969. We find that the eNOTc cyclone state is anticorrelated with the North Atlantic Oscillation (NAO) prior to 1977/1978. After 1977/1978, the cNOTe state is anticorrelated with both the NAO and the North Caspian Pattern (NCP), showing that the area of influence of large scale atmospheric teleconnections on regional cyclone activity shifted from the eastern to the central Mediterranean during the late 1970s. A trend toward more frequent occurrence of the positive phase of the NAO produced less frequent cNOTe states since the late 1970s, increasing the number of days with strong cooling of the Aegean Sea surface waters.</p> <div class="credits"> <p class="dwt_author">Romanski, Joy; Romanou, Anastasia; Bauer, Michael; Tselioudis, George</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">154</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.3025H"> <span id="translatedtitle">Formation and <span class="hlt">variability</span> of the south Pacific sea surface salinity maximum in recent <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This presentation investigates causes for the formation and the <span class="hlt">variability</span> of the Sea Surface Salinity (SSS) maximum of the South Pacific Ocean over the 1990-2011 period at the seasonal timescale and above. We use a monthly 1ºx1º gridded product of SSS based on in-situ measurements, high-resolution along-track Voluntary <span class="hlt">Observing</span> Ships thermosalinograph data, SMOS satellite data, and a validated ocean general circulation model with no direct SSS relaxation. All products reveal a zonal seasonal cycle of the location of the high (above 36 pss) SSS core barycentre of about 400 km in response to changes in the South Pacific Convergence Zone location and Easterly winds intensity. They also show an interannual westward shift of the barycentre of 1400 km. The possible origins of this shift, that could not be linked to the El Nino Southern Oscillation phenomena, are discussed. In the model, the processes maintaining the 22-year equilibrium of the high salinity in the mixed layer are the surface forcing (~+7 pss/yr), the horizontal salinity advection (~-3.5 pss/yr) and processes occurring at the mixed layer base (~-3.5 pss/yr).</p> <div class="credits"> <p class="dwt_author">Hasson, Audrey; Delcroix, Thierry; Boutin, Jacqueline</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">155</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=302477"> <span id="translatedtitle">Intra- to Multi-<span class="hlt">Decadal</span> Temperature <span class="hlt">Variability</span> over the Continental United States: 1896-2012</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p class="result-summary">The Optimal Ranking Regime (ORR) method was used to identify intra- to multi-<span class="hlt">decadal</span> (IMD) time windows containing significant ranking sequences in U.S. climate division temperature data. The simplicity of the ORR procedure’s output – a time series’ most significant non-overlapping periods of high o...</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">156</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1612390D"> <span id="translatedtitle">Predictable component of the <span class="hlt">observed</span> land <span class="hlt">variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A generalized multivariate regression method based on the Coupled Manifold technique [Navarra & Tribbia, 2005] is applied to decompose climate anomalies over land into a predictable component that is a remotely-forced signal from the ocean and a predictable component that is locally forced. The analysis is applied to the grand ENSEMBLES-CliPAS/APCC MME. Using the coupled manifold approach the MME retrospective forecasts have been used as predictor for 2-metres temperature <span class="hlt">observed</span> data (from ERA-INTERIM; Berrisford et al., 2009). The forecasts are projected through the coupled manifold into the target <span class="hlt">observation</span> using a cross-validation leave-one-out approach. In this way, it is evaluated how much of the real field <span class="hlt">variability</span> can be predicted based on the signal present in the ensemble forecasts. To simplify the computation the data are transformed beforehand by calculating the respective EOFs and then using the EOF coefficients in the analysis. It is found a considerable improvement of the performance over land compared with the poor original seasonal APCC-ENSEMBLES forecasts for JJA 1983-2005 considering 2-metres temperature. The Coupled Manifold is here proposed as a promising tool for the exploitation of the prediction signal over land.</p> <div class="credits"> <p class="dwt_author">De Felice, Matteo; Alessandri, Andrea; Catalano, Franco; Lee, Doo Young</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">157</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20150000358&hterms=ozone&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dozone"> <span id="translatedtitle">Highlights from a <span class="hlt">Decade</span> of OMI-TOMS Total Ozone <span class="hlt">Observations</span> on EOS Aura</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Total ozone measurements from OMI have been instrumental in meeting Aura science objectives. In the last <span class="hlt">decade</span>, OMI has extended the length of the TOMS total ozone record to over 35 years to monitor stratospheric ozone recovery. OMI-TOMS total ozone measurements have also been combined synergistically with measurements from other Aura instruments and MLS in particular, which provides vertically resolved information that complements the total O3 mapping capability of OMI. With this combined approach, the EOS Aura platform has produced more accurate and detailed measurements of tropospheric ozone. This has led in turn to greater understanding of the sources and transport of tropospheric ozone as well as its radiative forcing effect. The combined use of OMI and MLS data was also vital to the analysis of the severe Arctic ozone depletion event of 2011. The quality of OMI-TOMS total O3 data used in these studies is the result of several factors: a mature and well-validated algorithm, the striking stability of the OMI instrument, and OMI's hyperspectral capabilities used to derive cloud pressures. The latter has changed how we think about the effects of clouds on total ozone retrievals. We will discuss the evolution of the operational V8.5 algorithm and provide an overview and motivation for V9. After reviewing results and developments of the past <span class="hlt">decade</span>, we finally highlight how ozone <span class="hlt">observations</span> from EOS Aura are playing an important role in new ozone mapping missions.</p> <div class="credits"> <p class="dwt_author">Haffner, David P.; Bhartia, Pawan K.; McPeters, Richard D.; Joiner, Joanna; Ziemke, Jerald R.; Vassilkov, Alexander; Labow, Gordon J.; Chiou, Er-Woon</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">158</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://myweb.facstaff.wwu.edu/wallin/envr407/Peterson%20and%20Peterson%202001.pdf"> <span id="translatedtitle">Mountain Hemlock Growth Responds to Climatic <span class="hlt">Variability</span> at Annual and <span class="hlt">Decadal</span> Time Scales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Improved understanding of tree growth responses to climate is needed to model and predict forest ecosystem responses to current and future climatic <span class="hlt">variability</span>. We used dendroecological methods to study the effects of climatic <span class="hlt">variability</span> on radial growth of a subalpine conifer, mountain hemlock (Tsuga mertensiana). Tree-ring chronologies were developed for 31 sites, spanning the latitudinal and elevational ranges of mountain</p> <div class="credits"> <p class="dwt_author">David W. Peterson; David L. Peterson</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">159</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014HydJ...22.1825H"> <span id="translatedtitle">Watershed-scale response of groundwater recharge to inter-annual and inter-<span class="hlt">decadal</span> <span class="hlt">variability</span> in precipitation (Alberta, Canada)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Groundwater recharge sets a constraint on aquifer water balance in the context of water management. Historical data on groundwater and other relevant hydrological processes can be used to understand the effects of climatic <span class="hlt">variability</span> on recharge, but such data sets are rare. The climate of the Canadian prairies is characterized by large inter-annual and inter-<span class="hlt">decadal</span> <span class="hlt">variability</span> in precipitation, which provides opportunities to examine the response of groundwater recharge to changes in meteorological conditions. A <span class="hlt">decadal</span> study was conducted in a small (250 km2) prairie watershed in Alberta, Canada. Relative magnitude of annual recharge, indicated by water-level rise, was significantly correlated with a combination of growing-season precipitation and snowmelt runoff, which drives depression-focussed infiltration of meltwater. Annual precipitation was greater than vapour flux at an experimental site in some years and smaller in other years. On average precipitation minus vapour flux was 10 mm y-1, which was comparable to the magnitude of watershed-scale groundwater recharge estimated from creek baseflow. Average baseflow showed a distinct shift from a low value (4 mm y-1) in 1982-1995 to a high value (15 mm y-1) in 2003-2013, indicating the sensitivity of groundwater recharge to a <span class="hlt">decadal</span>-scale <span class="hlt">variability</span> of meteorological conditions.</p> <div class="credits"> <p class="dwt_author">Hayashi, Masaki; Farrow, Christopher R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">160</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20150000707&hterms=Flowers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DFlowers"> <span id="translatedtitle">A <span class="hlt">Decade</span> of Volcanic <span class="hlt">Observations</span> from Aura and the A-Train</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Aura <span class="hlt">observations</span> have made many seminal contributions to volcanology. Prior to the Aura launch, satellite <span class="hlt">observations</span> of volcanic degassing (e.g., from TOMS) were mostly restricted to large eruptions. However, the vast majority of volcanic gases are released during quiescent 'passive' degassing between eruptions. The improved sensitivity of Aura OMI permitted the first daily, space-borne measurements of passive volcanic SO2 degassing, providing improved constraints on the source locations and magnitude of global SO2 emissions for input to atmospheric chemistry and climate models. As a result of this unique sensitivity to volcanic activity, OMI data were also the first satellite SO2 measurements to be routinely used for volcano monitoring at several volcano observatories worldwide. Furthermore, the Aura OMI SO2 data also offer unprecedented sensitivity to volcanic clouds in the UTLS, elucidating the transport, fate and lifetime of volcanic SO2 and providing critical input to aviation hazard mitigation efforts. Another major advance has been the improved vertical resolution of volcanic clouds made possible by synergy between Aura and other A-Train instruments (e.g., AIRS, CALIPSO, CloudSat), advanced UV SO2 altitude retrievals, and inverse trajectory modeling of detailed SO2 cloud maps. This altitude information is crucial for climate models and aviation hazards. We will review some of the highlights of a <span class="hlt">decade</span> of Aura <span class="hlt">observations</span> of volcanic activity and look ahead to the future of volcanic <span class="hlt">observations</span> from space.</p> <div class="credits"> <p class="dwt_author">Carn, Simon A.; Krotkov, Nickolay Anatoly; Yang, Kai; Krueger, Arlin J.; Hughes, Eric J.; Wang, Jun; Flower, Verity; Telling, Jennifer</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_7");' href="#" 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<a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a style="font-weight: bold;">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_10");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">161</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/t10n11474664xj62.pdf"> <span id="translatedtitle"><span class="hlt">Decadal</span> Ocean Bottom Pressure <span class="hlt">Variability</span> and its Associated Gravitational Effects in a Coupled Ocean Atmosphere Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The launch of the Gravity Recovery and Climate Experiment (GRACE) satellite mission in March 2002 has made timely the study\\u000a of geophysical processes that redistribute the Earth’s mass. This study uses the Hadley Centre coupled ocean- atmosphere model\\u000a HadCM3 to examine the ocean’s role in mass redistribution on inter-annual to <span class="hlt">decadal</span> timescales. The leading empirical mode\\u000a of inter-annual bottom pressure</p> <div class="credits"> <p class="dwt_author">R. J. Bingham; K. Haines</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">162</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AGUFMGC43D0997K"> <span id="translatedtitle"><span class="hlt">Observation</span> of methane in this <span class="hlt">decade</span> by ground-based FTIR Spectrometer over Poker Flat, ALASKA</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Tropospheric CH4 is an important greenhouse gas as second largest radiative forcing in the troposphere with a long lifetime of ~10 years (Rinsland et. al., 2005). Poker Flat is a suitable location to detect CH4 abnormally due to Siberian/Alaskan biomass burning (Kasai et. al., 2005), volcano, and an anthropogenical emissions such as gas leakage from pipe-lines. We have been <span class="hlt">observed</span> troposheric CH4 over 10 years between 2000-2010 by using ground-based spectroscopic infrared solar absorption remote sensing measurement over Poker Flat, ALASKA (65.11N, 147.42W, 0.61km). CH4 vertical profiles were obtained by using SFIT2 ver.3.9 which incorporates Rodgers’ formulation of the Optimal Estimation Method (OEM) with an iterative Newton scheme (Rodgers, 2000). Frequency region of the CH4 is used 2600-2900 cm-1 region with the resolution 0.036cm-1. Seasonal and annual variation of the tropospheric CH4 in this <span class="hlt">decades</span> was obtained. Increasing trend of tropospheric CH4 was <span class="hlt">observed</span>. Several enhancement and depletion events were also <span class="hlt">observed</span>.</p> <div class="credits"> <p class="dwt_author">Kasai, Y.; Kagawa, A.; Jones, N. B.; Murayama, Y.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">163</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55758988"> <span id="translatedtitle">Investigating arctic cloud and radiative properties associated with the large-scale climate <span class="hlt">variability</span> through <span class="hlt">observations</span>, reanalysis, and mesoscale modeling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This dissertation examines two <span class="hlt">decades</span> of Arctic cloud cover data and the <span class="hlt">variability</span> in Arctic clouds with relation to changes in sea ice using <span class="hlt">observational</span> and reanalysis data, as well as a state-of-the-art mesoscale model. <span class="hlt">Decadal</span> length Arctic cloud cover data are examined because of the inherent differences within these measurements that have not been explored in previous research. Cloud</p> <div class="credits"> <p class="dwt_author">Neil P. Barton</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">164</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..1512493S"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">variability</span> of North Atlantic winter cyclone tracks in the 20C Reanalysis and MPI-ESM-LR</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Weather and climate in Central and Western Europe are strongly influenced by extra-tropical cyclones in the North Atlantic region. Therefore, the prediction of cyclones is of great interest. The MiKlip joint project aims at developing a <span class="hlt">decadal</span> prediction system with Europe as one focus area. As part of MiKlip, this study uses a cyclone tracking identification algorithm based on the Laplacian of sea level pressure to investigate the <span class="hlt">decadal</span> <span class="hlt">variability</span> of North Atlantic winter (ONDJFM) cyclone tracks. For this purpose, we develop a set of indices to describe the spatial extent as well as the orientation of the mean path of cyclone tracks and climatological cyclone track densities. Linking these indices to atmospheric and oceanic phenomena, such as the NAO and AMO, we seek to identify physical processes influencing the <span class="hlt">variability</span> of North Atlantic winter cyclone tracks. We use the Twentieth Century Reanalysis and the HadISST1.1 sea surface temperature datasets to create long-term (1871-2007) index time series and to identify these processes. The results from the reanalysis datasets are compared to <span class="hlt">decadal</span> hindcasts of the MPI-ESM-LR (contributor to cmip5). First results indicate problems of the model to reproduce the results from the reanalysis dataset.</p> <div class="credits"> <p class="dwt_author">Schyska, Bruno; Rust, Henning; Kruschke, Tim; Ulbrich, Uwe</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">165</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70026788"> <span id="translatedtitle">Tree-ring based reconstructions of interannual to <span class="hlt">decadal</span> scale precipitation <span class="hlt">variability</span> for northeastern Utah since 1226 A.D.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Samples from 107 pin??on pines (Pinus edulis) at four sites were used to develop a proxy record of annual (June to June) precipitation spanning the 1226 to 2001 AD interval for the Uinta Basin Watershed of northeastern Utah. The reconstruction reveals significant precipitation <span class="hlt">variability</span> at interannual to <span class="hlt">decadal</span> scales. Single-year dry events before the instrumental period tended to be more severe than those after 1900. In general, <span class="hlt">decadal</span> scale dry events were longer and more severe prior to 1900. In particular, dry events in the late 13th, 16th, and 18th Centuries surpass the magnitude and duration of droughts seen in the Uinta Basin after 1900. The last four <span class="hlt">decades</span> of the 20th Century also represent one of the wettest periods in the reconstruction. The proxy record indicates that the instrumental record (approximately 1900 to the Present) underestimates the potential frequency and severity of severe, sustained droughts in this area, while over representing the prominence of wet episodes. In the longer record, the empirical probability of any <span class="hlt">decadal</span> scale drought exceeding the duration of the 1954 through 1964 drought is 94 percent, while the probability for any wet event exceeding the duration of the 1965 through 1999 wet spell is only 1 percent. Hence, estimates of future water availability in the Uinta Basin and forecasts for exports to the Colorado River, based on the 1961 to 1990 and 1971 to 2000 "normal" periods, may be overly optimistic.</p> <div class="credits"> <p class="dwt_author">Gray, S.T.; Jackson, S.T.; Betancourt, J.L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">166</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/1127130"> <span id="translatedtitle">Collaborative Research: Separating Forced and Unforced <span class="hlt">Decadal</span> Predictability in Models and <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This report is a progress report of the accomplishments of the research grant “Collaborative Research: Separating Forced and Unforced <span class="hlt">Decadal</span> Predictability in Models and Observa- tions” during the period 1 May 2011- 31 August 2013. This project is a collaborative one between Columbia University and George Mason University. George Mason University will submit a final technical report at the conclusion of their no-cost extension. The purpose of the proposed research is to identify unforced predictable components on <span class="hlt">decadal</span> time scales, distinguish these components from forced predictable components, and to assess the reliability of model predictions of these components. Components of unforced <span class="hlt">decadal</span> predictability will be isolated by maximizing the Average Predictability Time (APT) in long, multimodel control runs from state-of-the-art climate models. Components with <span class="hlt">decadal</span> predictability have large APT, so maximizing APT ensures that components with <span class="hlt">decadal</span> predictability will be detected. Optimal fingerprinting techniques, as used in detection and attribution analysis, will be used to separate variations due to natural and anthropogenic forcing from those due to unforced <span class="hlt">decadal</span> predictability. This methodology will be applied to the <span class="hlt">decadal</span> hindcasts generated by the CMIP5 project to assess the reliability of model projections. The question of whether anthropogenic forcing changes <span class="hlt">decadal</span> predictability, or gives rise to new forms of <span class="hlt">decadal</span> predictability, also will be investigated.</p> <div class="credits"> <p class="dwt_author">Tippett, Michael K. [Columbia University</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-09</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">167</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JSR....82...67P"> <span id="translatedtitle">Four <span class="hlt">decades</span> of <span class="hlt">variability</span> in turbidity in the western Wadden Sea as derived from corrected Secchi disk readings</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Wadden Sea has undergone many changes of which some (e.g., seagrass disappearance, dredging activities) are thought to have affected the concentrations of suspended particulate matter (SPM) in these waters. Results of previous analyses of long-term variation and trends in SPM are, however, possibly biased by the fact that the data underlying these trends were not corrected for methodological changes in time. In this paper we analyze the <span class="hlt">variability</span> of Secchi disk measurements recorded at one location in the westernmost part of the Wadden Sea during almost four <span class="hlt">decades</span> (from 1974 to 2010). The Secchi readings were corrected for varying environmental conditions (solar zenith angle, solar irradiance and sea surface conditions) at the time of <span class="hlt">observation</span> and then converted to a turbidity proxy that measures the attenuation of light due to suspended and dissolved materials in the water column. We tested a series of hypotheses to describe the seasonal and long-term variations of this turbidity proxy. The best statistical model assumed one common seasonal pattern within the study period and a strong variation in turbidity over the years without any apparent long-term increase or decrease in time (n = 1361; r2 = 0.53). In addition, we found that most of the turbidity variation in this part of the Wadden Sea can be described as a function of SPM, chlorophyll-a, salinity, water temperature, the filter type used for the SPM determinations, and a still unidentified seasonal factor (n = 401; r2 = 0.88). Comparison with annual averaged ADCP-derived SPM concentrations as determined from a ferry sailing across the Marsdiep tidal inlet (1998-2008) showed that the <span class="hlt">variability</span> in turbidity at the sampling station was indicative for the variation in light attenuation in the westernmost part of the Wadden Sea. Because the intensity of the underwater light-field affects primary productivity, this new and consistent information on long-term variation in turbidity is of profound importance to the assessment of long-term changes and underlying mechanisms of the carrying capacity of the Wadden Sea.</p> <div class="credits"> <p class="dwt_author">Philippart, Catharina J. M.; Salama, Mhd. Suhyb; Kromkamp, Jacco C.; van der Woerd, Hendrik J.; Zuur, Alain F.; Cadée, Gerhard C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">168</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.3510C"> <span id="translatedtitle"><span class="hlt">Observed</span> variations of cloud fraction and types over Russia in last <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Cloudiness changes may mitigate or exacerbate global and local warming. Here, we assess changes of total and low cloud fraction and the occurrence of days with different cloud conditions and different cloud types including convective clouds over Russia from 1965 to 2011 years. Our analysis is based on visual daytime routine <span class="hlt">observations</span> from almost 500 Russian meteorological stations for the period 1965-2011 and than 1800 stations for the period 1984-2011. In general, cloud fraction tends to increase during the last years. A major increase of total cloud fraction and a decrease of the number of clear days are revealed in spring and autumn mostly due to an increase of the occurrence of convective and non-precipitating stratiform clouds. In contrast, the occurrence of Nimbostratus clouds tends to decrease, which lead to a general decrease of the occurrence of overcast days. In most regions, the ratio between the occurrence of Cumulonimbus and Nimbostratus clouds has increased in last <span class="hlt">decade</span> compare to previous ones. It worth noting, that for particular stations this redistribution may be associated with <span class="hlt">observers</span> changes. Over some regions (Ural and the Far East), a decrease of total cloud fraction and an increase of the number of clear days are noted. In addition, we assess possible causes of cloudiness variations. In particular, sensitivity of cloudiness changes to temperature changes were evaluated. The relationship of cloud variations with cyclonic/anticyclonic activity including atmospheric centers of action (Azores and Siberian highs, Aleutian and Icelandic lows) were assessed as well. An overall increase of convective clouds occurrence is an additional and independent evidence for the intensification of convective processes in the last <span class="hlt">decades</span> over land in the northern midlatitudes. Alongside with an increase of heavy precipitation events, an increase of occurrence of Cumulonimbus clouds leads to lightning occurrence increase and, in turn, leads to an increase of the risk of forest fire initiation. Together with the projected increase of fire danger indices in southern regions of the European Part and Siberia, it can lead to more fire hazardous regional climate. The work has been supported by the grant of the RF President MK-3259.2012.5 and by the Russian Foundation of Basic Research under grant 12-05-00972.</p> <div class="credits"> <p class="dwt_author">Chernokulsky, Alexander; Akperov, Mirseid; Bulygina, Olga; Mokhov, Igor; Nikitina, Natalia</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">169</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013BGD....1015455B"> <span id="translatedtitle">Oxygen minimum zone of the open Arabian Sea: <span class="hlt">variability</span> of oxygen and nitrite from daily to <span class="hlt">decadal</span> time scales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The oxygen minimum zone (OMZ) of the Arabian Sea is the thickest of the three oceanic OMZs, which is of global biogeochemical significance because of denitrification in the upper part leading to N2 and N2O production. The residence time of the OMZ water is believed to be less than a <span class="hlt">decade</span>. The upper few hundred meters of this zone are nearly anoxic but non-sulfidic and still support animal (metazoan) pelagic life, possibly as a result of episodic injections of O2 by physical processes. The very low O2 values obtained with the new STOX sensor in the eastern tropical South Pacific probably also characterize the Arabian Sea OMZ, but there is no apparent reason as to why the temporal trends of the historic data should not hold. We report on discrete measurements of dissolved O2 and NO2-, besides temperature and salinity, made between 1959 and 2004 well below the tops of the sharp pycno- and oxyclines near 150, 200, 300, 400, and 500 m depth. We assemble nearly all O2 determinations (originally, 849 values, 695 in the OMZ) by the visual endpoint detection of the iodometric Winkler procedure, which in our data base yields about 0.04 mL L-1 (∼2 ?M) O2 above the endpoint from modern automated titration methods. We find 632 values acceptable (480 from 150 stations in the OMZ). The data are grouped in zonally-paired boxes of 1° lat. and 2° long. centered at 8°, 10°, 12°, 15°, 18°, 20°, and 21° N along 65° E and 67° E. The latitudes of 8-12° N, outside the OMZ, are only treated in passing. The principal results are as follows: (1) an O2 climatology for the upper OMZ reveals a marked seasonality at 200 to 500 m depth with O2 levels during the northeast monsoon and spring intermonsoon season elevated over those during the southwest monsoon season (median difference, 0.08 mL L-1 [3.5 ?M]). The medians of the slopes of the seasonal regressions of O2 on year for the NE and SW monsoon seasons are -0.0043 and -0.0019 mL L-1 a-1, respectively (-0.19 and -0.08 ?M a-1; n = 10 and 12, differing at p = 0.01); (2) four <span class="hlt">decades</span> of statistically significant decreases of O2 between 15° and 20° N but a trend to a similar increase near 21° N are <span class="hlt">observed</span>. The balance of the mechanisms that more or less annually maintain the O2 levels are still uncertain. At least between 300 and 500 m the annual reconstitution of the decrease is inferred to be due to lateral, isopycnal re-supply of O2, while at 200 (250?) m it is diapycnal, most likely by eddies. Similarly, recent models show large vertical advection of O2 well below the pycno-cum-oxycline. The spatial (within drift stations) and temporal (daily) <span class="hlt">variability</span> in hydrography and chemistry is large also below the principal pycnocline. The seasonal change of hydrography is considerable even at 500 m. There is no trend in the redox environment for a quarter of a century at a GEOSECS station near 20° N. In the entire OMZ the slopes on year within seasons for the quite <span class="hlt">variable</span> NO2- (taken as an indicator of active denitrification) do not show a clear pattern. Also, future O2 or nutrient budgets for the OMZ should not be based on single cruises or sections obtained during one season only. Steady state cannot be assumed any longer for the intermediate layers of the central Arabian Sea.</p> <div class="credits"> <p class="dwt_author">Banse, K.; Naqvi, S. W. A.; Narvekar, P. V.; Postel, J. R.; Jayakumar, D. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">170</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://repository.tamu.edu/handle/1969.1/150993"> <span id="translatedtitle">Influence of Mean State on Climate <span class="hlt">Variability</span> at Interannual and <span class="hlt">Decadal</span> Time Scales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">concentration for the 1975 hindcast (red line). (b) <span class="hlt">Observed</span> volcanic aerosol (black line) and projected volcanic aerosol for the 1992 hindcast (red line). (c) <span class="hlt">Observed</span> annual solar constant (black line) and projected annual solar constant for the1975... series of the 1st year and the 10th year prediction ............................... 69 4.3 The <span class="hlt">observed</span> global annual SST (black), the GHG forcing (red), solar constant (purple), ozone concentration (blue) and Volcanic aerosol concentration (cyan...</p> <div class="credits"> <p class="dwt_author">Zhu, Xiaojie</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-05-17</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">171</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012SPIE.8524E..0TC"> <span id="translatedtitle">A <span class="hlt">decadal</span> <span class="hlt">observation</span> of vegetation dynamics using multi-resolution satellite images</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Vegetation cover not just affects the habitability of the earth, but also provides potential terrestrial mechanism for mitigation of greenhouse gases. This study aims at quantifying such green resources by incorporating multi-resolution satellite images from different platforms, including Formosat-2(RSI), SPOT(HRV/HRG), and Terra(MODIS), to investigate vegetation fractional cover (VFC) and its inter-/intra-annual variation in Taiwan. Given different sensor capabilities in terms of their spatial coverage and resolution, infusion of NDVIs at different scales was used to determine fraction of vegetation cover based on NDVI. Field campaign has been constantly conducted on a monthly basis for 6 years to calibrate the critical NDVI threshold for the presence of vegetation cover, with test sites covering IPCC-defined land cover types of Taiwan. Based on the proposed method, we analyzed spatio- temporal changes of VFC for the entire Taiwan Island. A bimodal sequence of VFC was <span class="hlt">observed</span> for intra-annual variation based on MODIS data, with level around 5% and two peaks in spring and autumn marking the principal dual-cropping agriculture pattern in southwestern Taiwan. Compared to anthropogenic-prone variation, the inter-annual VFC (Aug.-Oct.) derived from HRV/HRG/RSI reveals that the moderate variations (3%) and the oscillations were strongly linked with regional climate pattern and major disturbances resulting from extreme weather events. Two distinct cycles (2002-2005 and 2005-2009) were identified in the <span class="hlt">decadal</span> <span class="hlt">observations</span>, with VFC peaks at 87.60% and 88.12% in 2003 and 2006, respectively. This time-series mapping of VFC can be used to examine vegetation dynamics and its response associated with short-term and long-term anthropogenic/natural events.</p> <div class="credits"> <p class="dwt_author">Chiang, Yang-Sheng; Chen, Kun-Shan; Chu, Chang-Jen</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">172</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EPSC....9...86F"> <span id="translatedtitle">A <span class="hlt">Decade</span> of Cassini Radio Science <span class="hlt">Observations</span> of the Saturn System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Cassini Radio Science Subsystem (RSS) on board the Cassini spacecraft has returned a wealth ofinformation about the Saturn system during its first <span class="hlt">decade</span> of <span class="hlt">observations</span>. The instrumentation is quite versatile, operating in up to three wavelengths simultaneously (S, X, and Ka bands), and tied to a very stable frequency standard either on board or uplinked to the spacecraft from a maser-controlled transmitter as part of the Deep Space Network. Over the course of the mission so far, dozens of occultations by Saturn's rings have been <span class="hlt">observed</span>, revealing the detailed structure and scattering properties of the rings at sub-km resolution. A companion set of atmospheric occultations by Saturn and Titan have provided detailed vertical profiles of the temperature of the neutral atmosphere and the electron density of the ionosphere, spanning a range of latitudes and a significant fraction of a Saturn season. Operatin in a bistatic mode, the RSS instrument has transmitted signals to the surface of Titan at the specular point such that the reflected signal is received on the earth, revealing the dielectric properties of Titan's surface. Finally, exquisitely accurate measurements of the gravitationally induced Dopper shift of the RSS transmitted signal have provided measurements of the gravitations fields and probes of the internal structure of several of Saturn's major satellites, most notably indicating the presence of sub-surface oceans on both Titan and Enceladus. During the upcoming three-year finale of the Cassini mission, highlights of the remaining RSS science objectives include high- SNR measurements of the rings at their most favorable geometry of the entire Cassini orbital tour, and a set of close orbital fly-bys of Saturn itself, enabling the determination of the planet's gravitational field to an accuracy comparable to that expected for the Juno mission to Jupiter.</p> <div class="credits"> <p class="dwt_author">French, R.; Armstrong, J.; Flasar, M.; Iess, L.; Kliore, A.; Marouf, E.; McGhee, C.; Nagy, A.; Rappaport, N.; Schinder, P.; Tortora, P.; Anabtawi, A.; Asmar, S.; Barbinis, E.; Fleischmann, D.; Kahan, D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">173</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009EGUGA..11.6966D"> <span id="translatedtitle">An analysis of the <span class="hlt">decadal</span> <span class="hlt">variability</span> of Carbon fluxes in three evergreen European forests through modelling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With several sites measuring mass and energy turbulent fluxes for more than ten years, the CarboEurope database appears as a valuable resource for addressing the question of the determinism of the interannual <span class="hlt">variability</span> of carbon (C) and water balances in forests ecosystems. Apart from major climate-driven anomalies during the anomalous 2003 summer and 2007 spring, little is known about the factors driving interannual <span class="hlt">variability</span> (IAV) of the C balance in forest ecosystems. We used the CASTANEA process-based model to simulate the C and W fluxes and balances of three European evergreen forests for the 2000-2007 period (FRPue Quercus ilex, 44°N; DETha Picea abies, 51°N; FIHyy Pinus sylvestris, 62°N). The model fairly reproduced the day-to-day <span class="hlt">variability</span> of measured fluxes, accounting for 70-81%, 77-91% and 59-90% of the daily variance of measured NEP, GPP and TER, respectively. However, the model was challenged in representing the IAV of fluxes integrated on an annual time scale. It reproduced ca. 80% of the interannual variance of measured GPP, but no significant relationship could be established between annual measured and modelled NEP or TER. Accordingly, CASTANEA appeared as a suitable tool for disentangling the influence of climate and biological processes on GPP at mutiple time scales. We show that climate and biological processes relative influences on the modelled GPP vary from year to year in European evergreen forests. Water-stress related and phenological processes (i.e. release of the winter thermal constraint on photosynthesis in evergreens) appear as primary drivers for the particular 2003 and 2007 years, respectively, but the relative influence of other climatic factors widely varies for less remarkable years at all sites. We discuss shortcomings of the method, as related to the influence of compensating errors in the simulated fluxes, and assess the causes of the model poor ability to represent the IAV of the annual sums of NEP and TER.</p> <div class="credits"> <p class="dwt_author">Delpierre, N.; Dufrêne, E.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">174</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1611711W"> <span id="translatedtitle">Influence of climate <span class="hlt">variability</span> versus change at multi-<span class="hlt">decadal</span> time scales on hydrological extremes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Recent studies have shown that rainfall and hydrological extremes do not randomly occur in time, but are subject to multidecadal oscillations. In addition to these oscillations, there are temporal trends due to climate change. Design statistics, such as intensity-duration-frequency (IDF) for extreme rainfall or flow-duration-frequency (QDF) relationships, are affected by both types of temporal changes (short term and long term). This presentation discusses these changes, how they influence water engineering design and decision making, and how this influence can be assessed and taken into account in practice. The multidecadal oscillations in rainfall and hydrological extremes were studied based on a technique for the identification and analysis of changes in extreme quantiles. The statistical significance of the oscillations was evaluated by means of a non-parametric bootstrapping method. Oscillations in large scale atmospheric circulation were identified as the main drivers for the temporal oscillations in rainfall and hydrological extremes. They also explain why spatial phase shifts (e.g. north-south variations in Europe) exist between the oscillation highs and lows. Next to the multidecadal climate oscillations, several stations show trends during the most recent <span class="hlt">decades</span>, which may be attributed to climate change as a result of anthropogenic global warming. Such attribution to anthropogenic global warming is, however, uncertain. It can be done based on simulation results with climate models, but it is shown that the climate model results are too uncertain to enable a clear attribution. Water engineering design statistics, such as extreme rainfall IDF or peak or low flow QDF statistics, obviously are influenced by these temporal variations (oscillations, trends). It is shown in the paper, based on the Brussels 10-minutes rainfall data, that rainfall design values may be about 20% biased or different when based on short rainfall series of 10 to 15 years length, and still 8% for series of 25 years lengths. Methods for bias correction are demonstrated. The definition of "bias" depends on a number of factors, which needs further debate in the hydrological and water engineering community. References: Willems P. (2013), 'Multidecadal oscillatory behaviour of rainfall extremes in Europe', Climatic Change, 120(4), 931-944 Willems, P. (2013). 'Adjustment of extreme rainfall statistics accounting for multidecadal climate oscillations', Journal of Hydrology, 490, 126-133 Willems, P., Olsson, J., Arnbjerg-Nielsen, K., Beecham, S., Pathirana, A., Bülow Gregersen, I., Madsen, H., Nguyen, V-T-V. (2012), 'Impacts of climate change on rainfall extremes and urban drainage', IWA Publishing, 252p., Paperback Print ISBN 9781780401256; Ebook ISBN 9781780401263</p> <div class="credits"> <p class="dwt_author">Willems, Patrick</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">175</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.2198S"> <span id="translatedtitle">Interannual and sub-<span class="hlt">decadal</span> <span class="hlt">variability</span> in hydrography and nutrient concentrations in the Cariaco Basin</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Cariaco Basin is a deep (1400 m) permanently anoxic depression on the Venezuelan continental margin. First studied in the mid-1950s, it is the site of one of the longest time series of biogeochemical data in the ocean and for the past 18 years has been intensively studied by US and Venezuelan scientists through the CARIACO Ocean Times Series program. Although the basin's geochemistry was originally thought to be in steady state, data from CARIACO have demonstrated both long term trends and short term <span class="hlt">variability</span> in hydrography and nutrients at all depths. These trends are influenced by a number of factors including changes in the position of the ITCZ, the exchange of water between the Caribbean and the Cariaco Basin, and by changes in terrestrial influence. The long term trends include warming of surface waters by more than 1oC in 18 years, increases in surface fCO2 (2.95 +/- 0.43 micro-atmospheres kg-1 y-1) and nDIC (1.89 +/- 0.45 micromole kg-1 y-1), decreases in pH (0.0025 +/- 0.0004 y-1), and shifts in plankton community structure. Short-term <span class="hlt">variability</span> includes fluctuations in the depth and salinity of Subtropical Underwater and depth of the oxic/anoxic interface, changes in the depth and frequency of intrusions of oxygen-containing water into mid-depths, and episodic transport of terrestrial material into the basin after earthquakes or high precipitation events. Our results show that at least the upper 300-400 m of the water column is periodically (but not continuously) ventilated by water from the open Caribbean. Nutrient concentrations in the deep basin have increased steadily with time in a proportion reflective of the elemental ratios in the settling organic matter, although N:P ratios in the water column (for dissolved ammonium and phosphate in the sulfidic zone the ratio is approximately 16:1) differ from ratios for the accumulating nutrients (11:1) and the settling flux (approximately 5:1 to 12.5:1). This difference is likely due to long-term changes in the source material for remineralization, either because of sizeable ecosystem changes, changes in the relative importance of the terrestrial input of inorganic P or scavenging of P by mineral precipitation near the oxic/anoxic interface.</p> <div class="credits"> <p class="dwt_author">Scranton, Mary; Taylor, Gordon; Muller-Karger, Frank; Lorenzoni, Laura; Montes, Enrique; Fanning, Kent; Thunell, Robert; Benitez-Nelson, Claudia; Astor, Yrene; Varela, Ramon</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">176</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20030102176&hterms=parkinsons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dparkinsons"> <span id="translatedtitle">30-Year Satellite Record Reveals Contrasting Arctic and Antarctic <span class="hlt">Decadal</span> Sea Ice <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A 30-year satellite record of sea ice extents derived mostly from satellite microwave radiometer <span class="hlt">observations</span> reveals that the Arctic sea ice extent decreased by 0.30+0.03 x 10(exp 6) square kilometers per 10 yr from 1972 through 2002, but by 0.36 plus or minus 0.05 x 10(exp 6) square kilometers per 10yr from 1979 through 2002, indicating an acceleration of 20% in the rate of decrease. In contrast, the Antarctic sea ice extent decreased dramatically over the period 1973-1977, then gradually increased. Over the full 30-year period, the Antarctic ice extent decreased by 0.15 plus or minus 0.08 x 10(exp 6) square kilometers per 10 yr. The trend reversal is attributed to a large positive anomaly in Antarctic sea ice extent in the early 1970's, an anomaly that apparently began in the late 1960's, as <span class="hlt">observed</span> in early visible and infrared satellite images.</p> <div class="credits"> <p class="dwt_author">Cavalieri, D. J.; Parkinson, C. L.; Vinnikov, K. Y.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">177</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012HESS...16.1389D"> <span id="translatedtitle">Coupled <span class="hlt">decadal</span> <span class="hlt">variability</span> of the North Atlantic Oscillation, regional rainfall and karst spring discharges in the Campania region (southern Italy)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Thus far, studies on climate change have focused mainly on the <span class="hlt">variability</span> of the atmospheric and surface components of the hydrologic cycle, investigating the impact of this <span class="hlt">variability</span> on the environment, especially with respect to the risks of desertification, droughts and floods. Conversely, the impacts of climate change on the recharge of aquifers and on the <span class="hlt">variability</span> of groundwater flow have been less investigated, especially in Mediterranean karst areas whose water supply systems depend heavily upon groundwater exploitation. In this paper, long-term climatic <span class="hlt">variability</span> and its influence on groundwater recharge were analysed by examining <span class="hlt">decadal</span> patterns of precipitation, air temperature and spring discharges in the Campania region (southern Italy), coupled with the North Atlantic Oscillation (NAO). The time series of precipitation and air temperature were gathered over 90 yr, from 1921 to 2010, using 18 rain gauges and 9 air temperature stations with the most continuous functioning. The time series of the winter NAO index and of the discharges of 3 karst springs, selected from those feeding the major aqueducts systems, were collected for the same period. Regional normalised indexes of the precipitation, air temperature and karst spring discharges were calculated, and different methods were applied to analyse the related time series, including long-term trend analysis using smoothing numerical techniques, cross-correlation and Fourier analysis. The investigation of the normalised indexes highlighted the existence of long-term complex periodicities, from 2 to more than 30 yr, with differences in average values of up to approximately ±30% for precipitation and karst spring discharges, which were both strongly correlated with the winter NAO index. Although the effects of the North Atlantic Oscillation (NAO) had already been demonstrated in the long-term precipitation and streamflow patterns of different European countries and Mediterranean areas, the results of this study allow for the establishment of a link between a large-scale atmospheric cycle and the groundwater recharge of carbonate karst aquifers. Consequently, the winter NAO index could also be considered as a proxy to forecast the <span class="hlt">decadal</span> <span class="hlt">variability</span> of groundwater flow in Mediterranean karst areas.</p> <div class="credits"> <p class="dwt_author">De Vita, P.; Allocca, V.; Manna, F.; Fabbrocino, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">178</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JASTP.118...90J"> <span id="translatedtitle">Long-term trends and <span class="hlt">decadal</span> <span class="hlt">variability</span> of upper mesosphere/lower thermosphere gravity waves at midlatitudes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Mesosphere/lower thermosphere (MLT) winds over Germany as measured with a low-frequency spaced receiver system at Collm 1984-2007 have been analysed with respect to variations at the time scales of gravity waves. Background winds are also registered to analyse possible gravity wave-mean flow interactions at <span class="hlt">decadal</span> and interdecadal time scales. In both winter and summer an increasing mesospheric zonal wind jet with time is registered, which is accompanied with increasing gravity wave variances. At greater altitudes in summer, the mean wind jet trend reverses, and negative trends of gravity wave variances are found. This connection between gravity waves and mean wind is also <span class="hlt">observed</span> on a quasi-<span class="hlt">decadal</span> scale: during solar maximum stronger mesospheric zonal wind jets as well as larger gravity wave amplitudes are <span class="hlt">observed</span>. This results in a solar cycle modulation of gravity waves with larger amplitudes during solar maximum. The <span class="hlt">observed</span> positive correlation between gravity wave amplitudes and the mean zonal wind may follow the theory of saturated waves in the atmosphere, such that stronger mesospheric zonal winds are connected with larger gravity wave amplitudes.</p> <div class="credits"> <p class="dwt_author">Jacobi, Christoph</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">179</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014BGeo...11.2237B"> <span id="translatedtitle">Oxygen minimum zone of the open Arabian Sea: <span class="hlt">variability</span> of oxygen and nitrite from daily to <span class="hlt">decadal</span> timescales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The oxygen minimum zone (OMZ) of the Arabian Sea is the thickest of the three oceanic OMZ. It is of global biogeochemical significance because of denitrification in the upper part leading to N2 and N2O production. The residence time of OMZ water is believed to be less than a <span class="hlt">decade</span>. The upper few hundred meters of this zone are nearly anoxic but non-sulfidic and still support animal (metazoan) pelagic life, possibly as a result of episodic injections of O2 by physical processes. We report on discrete measurements of dissolved O2 and NO2-, temperature and salinity made between 1959 and 2004 well below the tops of the sharp pycnocline and oxycline near 150, 200, 300, 400, and 500 m depth. We assemble nearly all O2 determinations (originally there were 849 values, 695 of which came from the OMZ) by the visual endpoint detection of the iodometric Winkler procedure, which in our data base yields about 0.04 mL L-1 (~ 2 ?M) O2 above the endpoint from modern automated titration methods. We acknowledge that much lower (nanomolar) O2 values have been measured recently with the STOX (Switchable Trace amount OXygen) sensor in the eastern tropical South Pacific, and that similar conditions may also prevail in the Arabian Sea OMZ. In spite of the error in O2 measurements at vanishingly low levels, we argue that the temporal trends of the historic data should still hold. We find 632 values acceptable (480 from 150 stations in the OMZ). The data are grouped in zonally paired boxes of 1° lat. and 2° long. centered at 8, 10, 12, 15, 18, 20, and 21° N along 65 and 67° E. The latitudes of 8-12° N, outside the OMZ, are treated in passing. The principal results are as follows: (1) an O2 climatology for the upper OMZ reveals a marked seasonality at 200 to 500 m depth with O2 levels during the northeast monsoon and spring intermonsoon seasons elevated over those during the southwest monsoon season (median difference, 0.08 mL L-1 [~ 3.5 ?M]). The medians of the slopes of the seasonal regressions of O2 on year for each of the NE and SW monsoon seasons are -0.0043 and -0.0019 mL L-1 a-1, respectively (-0.19 and -0.08 ?M a-1; n = 10 and 12, differing at p = 0.01); (2) four <span class="hlt">decades</span> of statistically significant decreases of O2 between 15 and 20° N but an opposing trend toward an increase near 21° N are <span class="hlt">observed</span>. The mechanisms of the balance that more or less annually maintain the O2 levels are still uncertain. At least between 300 and 500 m, the replenishment is inferred to be due to isopycnal re-supply of O2, while at 200 (or 250?) m it is diapycnal, most likely by eddies. Similarly, recent models show large vertical advection of O2 well below the pycnoclines and oxyclines. The NO2- distribution, taken as an indicator of active NO3- reduction, does not show a trend in the redox environment for a quarter of a century at a GEOSECS station near 20° N. In the entire OMZ, the regression slopes on year within seasons for the rather <span class="hlt">variable</span> NO2- do not present a clear pattern but by other measures tended to an increase of NO2-. Vertical net hauls collect resident animal (metazoan) pelagic life in the NO2- maximum of the OMZ at O2 levels well below the lower limit of the Winkler titration; the extremely low O2 content is inferred from the presence of NO2- believed to be produced through microbial NO3- reduction. Instead of the difficult measurement by the STOX sensor, the relation between the very low O2 inferred from presence of NO2- and mesozooplankton should be studied with 100 to 150 L bottles rather than nets. The spatial (within drift stations) and temporal (daily) <span class="hlt">variability</span> in hydrography and chemistry is large also below the principal pycnocline. The seasonal change of hydrography is considerable even at 500 m depth. Future O2 or nutrient budgets for the OMZ must not be based on single cruises or sections obtained during one season only. Steady state cannot be assumed any longer for the intermediate layers of the central Arabian Sea.</p> <div class="credits"> <p class="dwt_author">Banse, K.; Naqvi, S. W. A.; Narvekar, P. V.; Postel, J. R.; Jayakumar, D. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">180</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011QuRes..75..483W"> <span id="translatedtitle">An 1800-yr record of <span class="hlt">decadal</span>-scale hydroclimatic <span class="hlt">variability</span> in the upper Arkansas River basin from bristlecone pine</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Bristlecone pine trees are exceptionally long-lived, and with the incorporation of remnant material have been used to construct multi-millennial length ring-width chronologies. These chronologies can provide valuable information about past temperature and moisture <span class="hlt">variability</span>. In this study, we outline a method to build a moisture-sensitive bristlecone chronology and assess the robustness and consistency of this sensitivity over the past 1200 yr using new reconstructions of Arkansas River flow (AD 1275-2002 and 1577-2002) and the summer Palmer Drought Sensitivity Index. The chronology, a composite built from parts of three collections in the central Rocky Mountains, is a proxy for <span class="hlt">decadal</span>-scale moisture <span class="hlt">variability</span> for the past 18 centuries. Since the sample size is small in some portions of the time series, the chronology should be considered preliminary; the timing and duration of drought events are likely the most robust characteristics. This chronology suggests that the region experienced increased aridity during the medieval period, as did much of western North America, but that the timing and duration of drought episodes within this period were somewhat different from those in other western locations, such as the upper Colorado River basin.</p> <div class="credits"> <p class="dwt_author">Woodhouse, Connie A.; Pederson, Gregory T.; Gray, Stephen T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-05-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_8");' href="#" 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showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_11");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">181</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://pubs.er.usgs.gov/publication/70033816"> <span id="translatedtitle">An 1800-yr record of <span class="hlt">decadal</span>-scale hydroclimatic <span class="hlt">variability</span> in the upper Arkansas River basin from bristlecone pine</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p class="result-summary">Bristlecone pine trees are exceptionally long-lived, and with the incorporation of remnant material have been used to construct multi-millennial length ring-width chronologies. These chronologies can provide valuable information about past temperature and moisture <span class="hlt">variability</span>. In this study, we outline a method to build a moisture-sensitive bristlecone chronology and assess the robustness and consistency of this sensitivity over the past 1200. yr using new reconstructions of Arkansas River flow (AD 1275-2002 and 1577-2002) and the summer Palmer Drought Sensitivity Index. The chronology, a composite built from parts of three collections in the central Rocky Mountains, is a proxy for <span class="hlt">decadal</span>-scale moisture <span class="hlt">variability</span> for the past 18 centuries. Since the sample size is small in some portions of the time series, the chronology should be considered preliminary; the timing and duration of drought events are likely the most robust characteristics. This chronology suggests that the region experienced increased aridity during the medieval period, as did much of western North America, but that the timing and duration of drought episodes within this period were somewhat different from those in other western locations, such as the upper Colorado River basin. ?? 2010 University of Washington.</p> <div class="credits"> <p class="dwt_author">Woodhouse, C.A.; Pederson, G.T.; Gray, S.T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">182</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014DSRII.103..264A"> <span id="translatedtitle">Understanding interannual, <span class="hlt">decadal</span> level <span class="hlt">variability</span> in paralytic shellfish poisoning toxicity in the Gulf of Maine: The HAB Index</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A major goal in harmful algal bloom (HAB) research has been to identify mechanisms underlying interannual <span class="hlt">variability</span> in bloom magnitude and impact. Here the focus is on <span class="hlt">variability</span> in Alexandrium fundyense blooms and paralytic shellfish poisoning (PSP) toxicity in Maine, USA, over 34 years (1978-2011). The Maine coastline was divided into two regions - eastern and western Maine, and within those two regions, three measures of PSP toxicity (the percent of stations showing detectable toxicity over the year, the cumulative amount of toxicity per station measured in all shellfish (mussel) samples during that year, and the duration of measurable toxicity) were examined for each year in the time series. These metrics were combined into a simple HAB Index that provides a single measure of annual toxin severity across each region. The three toxin metrics, as well as the HAB Index that integrates them, reveal significant <span class="hlt">variability</span> in overall toxicity between individual years as well as long-term, <span class="hlt">decadal</span> patterns or regimes. Based on different conceptual models of the system, we considered three trend formulations to characterize the long-term patterns in the Index - a three-phase (mean-shift) model, a linear two-phase model, and a pulse-decline model. The first represents a “regime shift” or multiple equilibria formulation as might occur with alternating periods of sustained high and low cyst abundance or favorable and unfavorable growth conditions, the second depicts a scenario of more gradual transitions in cyst abundance or growth conditions of vegetative cells, and the third characterizes a ”sawtooth” pattern in which upward shifts in toxicity are associated with major cyst recruitment events, followed by a gradual but continuous decline until the next pulse. The fitted models were compared using both residual sum of squares and Akaike's Information Criterion. There were some differences between model fits, but none consistently gave a better fit than the others. This statistical underpinning can guide efforts to identify physical and/or biological mechanisms underlying the patterns revealed by the HAB Index. Although A. fundyense cyst survey data (limited to 9 years) do not span the entire interval of the shellfish toxicity records, this analysis leads us to hypothesize that major changes in the abundance of A. fundyense cysts may be a primary factor contributing to the <span class="hlt">decadal</span> trends in shellfish toxicity in this region. The HAB Index approach taken here is simple but represents a novel and potentially useful tool for resource managers in many areas of the world subject to toxic HABs.</p> <div class="credits"> <p class="dwt_author">Anderson, Donald M.; Couture, Darcie A.; Kleindinst, Judith L.; Keafer, Bruce A.; McGillicuddy, Dennis J., Jr.; Martin, Jennifer L.; Richlen, Mindy L.; Hickey, J. Michael; Solow, Andrew R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">183</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19950008093&hterms=deep+israel&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddeep%2Bisrael"> <span id="translatedtitle">FRESIP project <span class="hlt">observations</span> of cataclysmic <span class="hlt">variables</span>: A unique opportunity</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">FRESIP Project <span class="hlt">observations</span> of cataclysmic <span class="hlt">variables</span> would provide unique data sets. In the study of known cataclysmic <span class="hlt">variables</span> they would provide extended, well sampled temporal photometric information and in addition, they would provide a large area deep survey; obtaining a complete magnitude limited sample of the galaxy in the volume cone defined by the FRESIP field of view.</p> <div class="credits"> <p class="dwt_author">Howell, Steve B.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">184</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=outcome+AND+variable&id=EJ879637"> <span id="translatedtitle">Bayesian Network Models for Local Dependence among <span class="hlt">Observable</span> Outcome <span class="hlt">Variables</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Bayesian network models offer a large degree of flexibility for modeling dependence among <span class="hlt">observables</span> (item outcome <span class="hlt">variables</span>) from the same task, which may be dependent. This article explores four design patterns for modeling locally dependent <span class="hlt">observations</span>: (a) no context--ignores dependence among <span class="hlt">observables</span>; (b) compensatory context--introduces…</p> <div class="credits"> <p class="dwt_author">Almond, Russell G.; Mulder, Joris; Hemat, Lisa A.; Yan, Duanli</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">185</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..12.2164D"> <span id="translatedtitle">An analysis of the <span class="hlt">decadal</span> <span class="hlt">variability</span> of Carbon fluxes in European forests through process-based modelling</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">With several sites measuring mass and energy turbulent fluxes for more than ten years, the CarboEurope database appears as a valuable resource for addressing the question of the determinism of the interannual <span class="hlt">variability</span> of carbon (C) balance in forests ecosystems. Apart from major climate-driven anomalies during the anomalous 2003 summer and 2007 spring, little is known about the factors driving interannual <span class="hlt">variability</span> (IAV) of the C balance in European forests. We used the CASTANEA process-based model to simulate the C balances of four European forests for the 2000-2007 period, spanning a large latitudinal range (44-62°N). The model fairly reproduced the day-to-day <span class="hlt">variability</span> of measured fluxes, and accounted for 36-82% (mean=63%, n=4) of the <span class="hlt">observed</span> interannual variance in daytime NEP. We used CASTANEA as a tool for disentangling the influence of climate and biological drivers on C fluxes at mutiple time scales. A set of constrained simulation was performed to identify the proper effects of climate (PAR, temperature, relative humidity, soil water content) and biological drivers (canopy phenology, plant and soil C stocks) on flux <span class="hlt">variability</span>. Their relative contributions to flux variance across timescales was quantified through orthonormal wavelet decomposition of the single-driver effects time series. As a general feature, we <span class="hlt">observed</span> a declining contribution of climate drivers to flux (GPP, Reco or NEP) interannual variance from daily to annual timescale. Our analyses revealed that most (40-90%, mean=70%) of the simulated NEP interannual variance at annual scale was caused by climate anomalies, with biological drivers playing a more modest role in such mature and relatively undisturbed forests. We contrast results obtained through this novel process-based modelling approach with those arising from more classical data-mining analyses. Keywords: Process-based model, interannual <span class="hlt">variability</span>, Carbon balance, water balance, phenology, biological drivers, climate drivers.</p> <div class="credits"> <p class="dwt_author">Delpierre, Nicolas; Soudani, Kamel; François, Christophe; Bernhofer, Christian; Kutsch, Werner; Misson, Laurent; Vesala, Timo; Dufrêne, Eric</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">186</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/2025040"> <span id="translatedtitle">The Tropical Ocean-Global Atmosphere <span class="hlt">observing</span> system: A <span class="hlt">decade</span> of progress</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">A major accomplishment of the recently completed Tropical Ocean-Global Atmosphere (TOGA) Program was the development of an ocean <span class="hlt">observing</span> system to support seasonal-to-interannual climate studies. This paper reviews the scientific motivations for the development of that <span class="hlt">observing</span> system, the technological advances that made it possible, and the scientific advances that resulted from the availability of a significantly expanded <span class="hlt">observational</span> database.</p> <div class="credits"> <p class="dwt_author">Michael J. McPhaden; Antonio J. Busalacchi; Robert Cheney; Jean-René Donguy; Kenneth S. Gage; David Halpern; Ming Ji; Paul Julian; Gary Meyers; Gary T. Mitchum; Pearn P. Niiler; Joel Picaut; Richard W. Reynolds; Neville Smith; Kensuke Takeuchi</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">187</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014HESS...18.2235V"> <span id="translatedtitle">Links between the Big Dry in Australia and hemispheric multi-<span class="hlt">decadal</span> climate <span class="hlt">variability</span> - implications for water resource management</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Southeast Australia (SEA) experienced a protracted drought during the mid-1990s until early 2010 (known as the Big Dry or Millennium Drought) that resulted in serious environmental, social and economic effects. This paper analyses a range of historical climate data sets to place the recent drought into context in terms of Southern Hemisphere inter-annual to multi-<span class="hlt">decadal</span> hydroclimatic <span class="hlt">variability</span>. The findings indicate that the recent Big Dry in SEA is in fact linked to the widespread Southern Hemisphere climate shift towards drier conditions that began in the mid-1970s. However, it is shown that this link is masked because the large-scale climate drivers responsible for drying in other regions of the mid-latitudes since the mid-1970s did not have the same effect on SEA during the mid- to late 1980s and early 1990s. More specifically, smaller-scale synoptic processes resulted in elevated autumn and winter rainfall (a crucial period for SEA hydrology) during the mid- to late 1980s and early 1990s, which punctuated the longer-term drying. From the mid-1990s to 2010 the frequency of the synoptic processes associated with elevated autumn/winter rainfall decreased, resulting in a return to drier than average conditions and the onset of the Big Dry. The findings presented in this paper have marked implications for water management and climate attribution studies in SEA, in particular for understanding and dealing with "baseline" (i.e. current) hydroclimatic risks.</p> <div class="credits"> <p class="dwt_author">Verdon-Kidd, D. C.; Kiem, A. S.; Moran, R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">188</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011HESSD...811233D"> <span id="translatedtitle">Coupled <span class="hlt">decadal</span> <span class="hlt">variability</span> of the North Atlantic Oscillation, regional rainfall and spring discharges in the Campania region (Southern Italy)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Climate change is one of the issues most debated by the scientific community with a special focus to the combined effects of anthropogenic modifications of the atmosphere and the natural climatic cycles. Various scenarios have been formulated in order to forecast the global atmospheric circulation and consequently the <span class="hlt">variability</span> of the global distribution of air temperature and rainfall. The effects of climate change have been analysed with respect to the risks of desertification, droughts and floods, remaining mainly limited to the atmospheric and surface components of the hydrologic cycle. Consequently the impact of the climate change on the recharge of regional aquifers and on the groundwater circulation is still a challenging topic especially in those areas whose aqueduct systems depend basically on springs or wells, such as the Campania region (Southern Italy). In order to analyse the long-term climatic <span class="hlt">variability</span> and its influence on groundwater circulation, we analysed <span class="hlt">decadal</span> patterns of precipitation, air temperature and spring discharges in the Campania region (Southern Italy), coupled with the North Atlantic Oscillation (NAO). The time series of precipitation and air temperature were gathered over 90 yr, in the period from 1921 to 2010, choosing 18 rain gauges and 9 air temperature stations among those with the most continuous functioning as well as arranged in a homogeneous spatial distribution. Moreover, for the same period, we gathered the time series of the winter NAO index (December to March mean) and of the discharges of the Sanità spring, belonging to an extended carbonate aquifer (Cervialto Mount) located in the central-eastern area of the Campania region, as well as of two other shorter time series of spring discharges. The hydrogeological features of this aquifer, its relevance due to the feeding of an important regional aqueduct system, as well as the unique availability of a long-lasting time series of spring discharges, allowed us to consider it as an ideal test site, representative of the other carbonate aquifers in the Campania region. The time series of regional normalised indexes of mean annual precipitation, mean annual air temperature and mean annual effective precipitation, as well as the time series of the normalised annual discharge index were calculated. Different methods were applied to analyse the time series: long-term trend analysis, through smoothing numerical techniques, cross-correlation and Fourier analysis. The investigation of the normalised indexes has highlighted long-term complex periodicities, strongly correlated with the winter NAO index. Moreover, we also found robust correlations among precipitation indexes and the annual discharge index, as well as between the latter and the NAO index itself. Although the effects of the North Atlantic Oscillation had already been proved on long-term precipitation and streamflow patterns of different European countries and Mediterranean areas, the results obtained appear original because they establish a link between a large-scale atmospheric cycle and the groundwater circulation of regional aquifers. Therefore, we demonstrated that the winter NAO index can be considered as an effective proxy to forecast the <span class="hlt">decadal</span> <span class="hlt">variability</span> of groundwater circulation in Mediterranean areas and in estimating critical scenarios for the feeding of aqueduct systems.</p> <div class="credits"> <p class="dwt_author">de Vita, P.; Allocca, V.; Manna, F.; Fabbrocino, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">189</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.3407A"> <span id="translatedtitle">Monitoring multi-<span class="hlt">decadal</span> satellite earth <span class="hlt">observation</span> of soil moisture using era-land global land water resources dataset</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It has been widely recognized that soil moisture is one of the main drivers of the water, energy and carbon cycles. It is a crucial <span class="hlt">variable</span> for Numerical Weather Prediction (NWP) and climate projections because it plays a key role in hydro-meteorological processes. A good representation of soil moisture conditions can help improving the forecasting of precipitation, temperature, droughts and floods. For many applications global or continental scale soil moisture maps are needed. As a consequence, a signi?cant amount of studies have been conducted to obtain such information. For that purpose, land surface modeling, remote sensing techniques or a combination of both through Land Data Assimilation Systems are used. Assessing the quality of these products is required and for instance, the release of a new -long term- harmonized soil moisture product (SM-MW hereafter) from remote sensing within the framework of the European Space Agency's Water Cycle Multi-mission <span class="hlt">Observation</span> Strategy (WACMOS) and Climate Change Initiative (CCI) projects in 2012 (more information at http://www.esa-soilmoisture-cci.org/) triggered several evaluation activities. The typical validation approach for model and satellite based data products is to compare them to in situ <span class="hlt">observations</span>. However the evaluation of soil moisture products using ground measurements is not trivial. Even if in the recent years huge efforts were made to make such <span class="hlt">observations</span> available in contrasting biomes and climate conditions, long term and large scale ground measurements networks are still sparse. Additionally, different networks will present different characteristics (e.g. measurement methods, installation depths and modes, calibration techniques, measurement interval, and temporal and spatial coverage). Finally using in situ measurements, the quality of retrieved soil moisture can be accurately assessed for the locations of the stations. That is why it is of interest to conceive new validation methods, complementing the existing soil moisture networks. To do so Land Surface Models (LSM) can be used to upscale the in situ surface soil moisture <span class="hlt">observations</span> and complete the evaluation of satellite derived products, assuming that land surface models, forced with high quality atmospheric forcing data, adequately capture the soil moisture temporal dynamic. In this study, SM-MW is first evaluated using ground measurements of soil moisture over 2007-2010. Along with SM-MW, soil moisture from two revised re-analyses; ERA-Land, an update of the land surface component of the ERA-Interim reanalysis from the European Centre for Medium-Range Weather Forecasts (ECMWF) and MERRA-Land, an enhanced land surface data product based on MERRA reanalysis by the National Aeronautics and Space Administration (NASA) were evaluated, also. In situ measurements from almost 200 stations from five networks in different countries (USA, Spain, France, China and Australia) were considered. Then soil moisture from ERA-Land, is used to monitor at a global scale the consistency of SM-MW over multi-<span class="hlt">decadal</span> time period (1980-2010).</p> <div class="credits"> <p class="dwt_author">Albergel, Clement; Dorigo, Wouter; Balsamo, Gianpaolo; de Rosnay, Patricia; Muñoz-Sabater, Joaquin; Isaksen, Lars; Brocca, Luca; de Jeu, Richard; Wagner, Wolfgang</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">190</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006cosp...36.2610Y"> <span id="translatedtitle">Near-infrared <span class="hlt">observations</span> of the <span class="hlt">variable</span> crab nebula</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present three near-infrared NIR <span class="hlt">observations</span> of the Crab Nebula obtained with CISCO on the Subaru Telescope and Quick Infrared Camera on the University of HAWAII 88 inch Telescope The <span class="hlt">observations</span> were performed on 2004 September 2005 February and 2005 October and were coordinated with X-ray <span class="hlt">observations</span> obtained with the Chandra X-ray observatory within 10 days As shown in previous optical and X-ray monitoring <span class="hlt">observations</span> outward-moving wisps and <span class="hlt">variable</span> knots are detected also in our NIR <span class="hlt">observations</span> The NIR variations are closely correlated with variations in the X-ray <span class="hlt">observations</span> indicating that both variations are driven by the same physical process We discuss the origin of NIR-emitting particles based on the temporal variations as well as the spectral energy distributions of each <span class="hlt">variable</span> component</p> <div class="credits"> <p class="dwt_author">Yamamoto, M.; Mori, K.; Shibata, S.; Tsujimoto, M.; Misawa, T.; Burrows, D.; Kawai, N.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">191</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/55920958"> <span id="translatedtitle">SMC X-1 <span class="hlt">variability</span> <span class="hlt">observed</span> from HEAO 1</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Studies are reported of the slow <span class="hlt">variability</span> of SMC X-1 and its spectrum. An analysis of red-noise random <span class="hlt">variability</span> is based on a method discussed by Deeter and Boynton (1982). The 0.7 s X-ray pulsar SMC X-1 is in a 3.89 day eclipsing binary system with a B0 I supergiant companion. <span class="hlt">Observations</span> of the pulsar were conducted with the aid</p> <div class="credits"> <p class="dwt_author">D. E. Gruber; R. E. Rothschild</p> <p class="dwt_publisher"></p> <p class="publishDate">1984-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">192</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.astro.umd.edu/people/Theses/2008Mattson.pdf"> <span id="translatedtitle">Title of Dissertation: A <span class="hlt">Decade</span> of Rossi X-ray Timing Explorer Seyfert <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">-loud and radio- quiet Seyfert 1s. This can be explained if X-rays from the relativistic jet in radio-loud sources. This relationship can also be explained by jet-related phenomena, such that the flatter X-ray spectrum from the jet or a time-lag between changes in the X- ray continuum and changes in the iron line. We do not <span class="hlt">observe</span></p> <div class="credits"> <p class="dwt_author">Gruner, Daniel S.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">193</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20070038262&hterms=latent&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dlatent"> <span id="translatedtitle">Interannual and <span class="hlt">Decadal</span> <span class="hlt">Variability</span> of Ocean Surface Latent Heat Flux as Seen from Passive Microwave Satellite Algorithms</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Ocean surface turbulent fluxes are critical links in the climate system since they mediate energy exchange between the two fluid systems (ocean and atmosphere) whose combined heat transport determines the basic character of Earth's climate. Deriving physically-based latent and sensible heat fluxes from satellite is dependent on inferences of near surface moisture and temperature from coarser layer retrievals or satellite radiances. Uncertainties in these "retrievals" propagate through bulk aerodynamic algorithms, interacting as well with error properties of surface wind speed, also provided by satellite. By systematically evaluating an array of passive microwave satellite algorithms, the SEAFLUX project is providing improved understanding of these errors and finding pathways for reducing or eliminating them. In this study we focus on evaluating the interannual <span class="hlt">variability</span> of several passive microwave-based estimates of latent heat flux starting from monthly mean gridded data. The algorithms considered range from those based essentially on SSM/I (e.g. HOAPS) to newer approaches that consider additional moisture information from SSM/T-2 or AMSU-B and lower tropospheric temperature data from AMSU-A. On interannual scales, <span class="hlt">variability</span> arising from ENSO events and time-lagged responses of ocean turbulent and radiative fluxes in other ocean basins (as well as the extratropical Pacific) is widely recognized, but still not well quantified. Locally, these flux anomalies are of order 10-20 W/sq m and present a relevant "target" with which to verify algorithm performance in a climate context. On <span class="hlt">decadal</span> time scales there is some evidence from reanalyses and remotely-sensed fluxes alike that tropical ocean-averaged latent heat fluxes have increased 5-10 W/sq m since the early 1990s. However, significant uncertainty surrounds this estimate. Our work addresses the origin of these uncertainties and provides statistics on time series of tropical ocean averages, regional space / time correlation analysis, and separation of contributions by variations in wind and near surface humidity deficit. Comparison to variations in reanalysis data sets is also provided for reference.</p> <div class="credits"> <p class="dwt_author">Robertson, Franklin R.; Jackson, Darren L.; Wick, Gary A.; Roberts, Brent; Miller, Tim L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">194</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1998ovsg.book.....L"> <span id="translatedtitle"><span class="hlt">Observing</span> <span class="hlt">Variable</span> Stars, A Guide for the Beginner</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">David Levy's entertaining, well-researched book is aimed at the amateur enthusiast who likes to learn enjoyably. Beginning with advice on binoculars and telescopes, and how to <span class="hlt">observe</span> the night sky effectively, the author goes on to describe thoroughly the field of <span class="hlt">variable</span> star <span class="hlt">observation</span>, a field in which amateurs have made important contributions. He shows how to interpret variations in light output in terms of the life of a star, from birth through to sometimes violent death. All of the major <span class="hlt">variable</span> stars are described and classified, as well as other <span class="hlt">variable</span> objects such as active galaxies, asteroids, comets and the sun. The book also contains a guide to the seasonal night sky. Throughout, practical <span class="hlt">observations</span> serve to complement the text, producing an exciting, very readable introduction to this fascinating subject.</p> <div class="credits"> <p class="dwt_author">Levy, David H.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">195</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/24416214"> <span id="translatedtitle">Coral luminescence identifies the Pacific <span class="hlt">Decadal</span> Oscillation as a primary driver of river runoff <span class="hlt">variability</span> impacting the southern Great Barrier Reef.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The Pacific <span class="hlt">Decadal</span> Oscillation (PDO) is a large-scale climatic phenomenon modulating ocean-atmosphere <span class="hlt">variability</span> on <span class="hlt">decadal</span> time scales. While precipitation and river flow <span class="hlt">variability</span> in the Great Barrier Reef (GBR) catchments are sensitive to PDO phases, the extent to which the PDO influences coral reefs is poorly understood. Here, six Porites coral cores were used to produce a composite record of coral luminescence <span class="hlt">variability</span> (runoff proxy) and identify drivers of terrestrial influence on the Keppel reefs, southern GBR. We found that coral skeletal luminescence effectively captured seasonal, inter-annual and <span class="hlt">decadal</span> <span class="hlt">variability</span> of river discharge and rainfall from the Fitzroy River catchment. Most importantly, although the influence of El Niño-Southern Oscillation (ENSO) events was evident in the luminescence records, the <span class="hlt">variability</span> in the coral luminescence composite record was significantly explained by the PDO. Negative luminescence anomalies (reduced runoff) were associated with El Niño years during positive PDO phases while positive luminescence anomalies (increased runoff) coincided with strong/moderate La Niña years during negative PDO phases. This study provides clear evidence that not only ENSO but also the PDO have significantly affected runoff regimes at the Keppel reefs for at least a century, and suggests that upcoming hydrological disturbances and ecological responses in the southern GBR region will be mediated by the future evolution of these sources of climate <span class="hlt">variability</span>. PMID:24416214</p> <div class="credits"> <p class="dwt_author">Rodriguez-Ramirez, Alberto; Grove, Craig A; Zinke, Jens; Pandolfi, John M; Zhao, Jian-xin</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">196</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3885547"> <span id="translatedtitle">Coral Luminescence Identifies the Pacific <span class="hlt">Decadal</span> Oscillation as a Primary Driver of River Runoff <span class="hlt">Variability</span> Impacting the Southern Great Barrier Reef</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">The Pacific <span class="hlt">Decadal</span> Oscillation (PDO) is a large-scale climatic phenomenon modulating ocean-atmosphere <span class="hlt">variability</span> on <span class="hlt">decadal</span> time scales. While precipitation and river flow <span class="hlt">variability</span> in the Great Barrier Reef (GBR) catchments are sensitive to PDO phases, the extent to which the PDO influences coral reefs is poorly understood. Here, six Porites coral cores were used to produce a composite record of coral luminescence <span class="hlt">variability</span> (runoff proxy) and identify drivers of terrestrial influence on the Keppel reefs, southern GBR. We found that coral skeletal luminescence effectively captured seasonal, inter-annual and <span class="hlt">decadal</span> <span class="hlt">variability</span> of river discharge and rainfall from the Fitzroy River catchment. Most importantly, although the influence of El Niño-Southern Oscillation (ENSO) events was evident in the luminescence records, the <span class="hlt">variability</span> in the coral luminescence composite record was significantly explained by the PDO. Negative luminescence anomalies (reduced runoff) were associated with El Niño years during positive PDO phases while positive luminescence anomalies (increased runoff) coincided with strong/moderate La Niña years during negative PDO phases. This study provides clear evidence that not only ENSO but also the PDO have significantly affected runoff regimes at the Keppel reefs for at least a century, and suggests that upcoming hydrological disturbances and ecological responses in the southern GBR region will be mediated by the future evolution of these sources of climate <span class="hlt">variability</span>. PMID:24416214</p> <div class="credits"> <p class="dwt_author">Rodriguez-Ramirez, Alberto; Grove, Craig A.; Zinke, Jens; Pandolfi, John M.; Zhao, Jian-xin</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">197</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..1611025P"> <span id="translatedtitle">The ENSO or there and back again. Trying to understand the connection between its <span class="hlt">decadal</span> <span class="hlt">variability</span> and processes indexed by PDO, NAO and AMO</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Recent research suggests that <span class="hlt">decadal</span> <span class="hlt">variability</span> in ENSO influence not only tropical Pacific SST values but also modulate the rate of change of global temperatures. It may be the main reason for the so called "global warming hiatus" of recent years. This makes it not only an interesting subject of scientific studies but also a subject of interest for general population. Especially predicting average <span class="hlt">decadal</span> ENSO activity would be important, if it would help predict the rate of global warming on <span class="hlt">decadal</span> scales. The only hope for such predictions in foreseeable future would come from understanding the relationship of ENSO <span class="hlt">variability</span> in <span class="hlt">decadal</span> scales to cycles of natural <span class="hlt">variability</span>. Several climate indices have quasi-cyclical components of about 60-70 years. The most obvious example is AMO, a proxy for Atlantic meridional overturning circulation (AMOC) <span class="hlt">variability</span>. However also <span class="hlt">variability</span> of NAO, the index of atmospheric zonal circulation in the North Atlantic sector, has component of similar period significantly correlated with AMO lagged by about 15 years. Even <span class="hlt">variability</span> of PDO the index of multidecadal <span class="hlt">variability</span> in Northern Pacific has a component of similar period and phase as NAO. Then, PDO correlates also with ENSO on <span class="hlt">decadal</span> scales. Correlation does not imply causation. This raises the question whether there are physical mechanisms behind the correlations. Tropical Pacific temperatures have been shown to influence surface pressure in the North Eastern Pacific influencing zonal circulation which may explain the PDO - NAO "teleconnection". Zonal winds influence the rate of deep water production in Labrador and Greenland seas, which may explain its influence on the rate of change in deep water production (the NAO - AMO correlation lagged by ¼ cycle). AMO being a proxy of AMOC (heat transport from South to North Hemisphere) obviously influences the inter-hemispherical temperature difference. We have recently showed the statistically significant anticorrelation of this NH-SH temperature difference on ENSO, explaining it by the influence on the position of ITCZ and trade winds. We use statistical analysis of climate indices and discuss the underlying physical processes to argue for existence of causal connection between them. This study tries to create a framework for understanding climate <span class="hlt">variability</span> in Pacific and Atlantic sectors on multidecadal scales as a quasi-cycle of about 65 years involving both ocean and atmospheric circulation involving processes indexed by PDO, NAO, AMO and influencing ENSO <span class="hlt">variability</span> on <span class="hlt">decadal</span> scales. We do not believe this is the final word in this field. Rather a good start.</p> <div class="credits"> <p class="dwt_author">Piskozub, Jacek; Gutowska, Dorota</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">198</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://polarmet.osu.edu/PMG_publications/fogt_bromwich_jc_2006.pdf"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">Variability</span> of the ENSO Teleconnection to the High-Latitude South Pacific Governed by Coupling with the Southern Annular Mode*</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">between the Pacific­South American (PSA) pattern associated with ENSO and the Southern Annular Mode (SAM in the amplitude of this pressure center, which is part of the Pacific­South American (PSA) pattern (Mo and Ghil<span class="hlt">Decadal</span> <span class="hlt">Variability</span> of the ENSO Teleconnection to the High-Latitude South Pacific Governed</p> <div class="credits"> <p class="dwt_author">Howat, Ian M.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">199</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/41330135"> <span id="translatedtitle">High nutrient pulses, tidal mixing and biological response in a small California estuary: <span class="hlt">Variability</span> in nutrient concentrations from <span class="hlt">decadal</span> to hourly time scales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Elkhorn Slough is a small estuary in Central California, where nutrient inputs are dominated by runoff from agricultural row crops, a golf course, and residential development. We examined the <span class="hlt">variability</span> in nutrient concentrations from <span class="hlt">decadal</span> to hourly time scales in Elkhorn Slough to compare forcing by physical and biological factors. Hourly data were collected using in situ nitrate analyzers and</p> <div class="credits"> <p class="dwt_author">Jane M. Caffrey; Thomas P. Chapin; Hans W. Jannasch; John C. Haskins</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">200</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGRD..11910262R"> <span id="translatedtitle">Temporal <span class="hlt">variability</span> of <span class="hlt">observed</span> and simulated hyperspectral reflectance</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Multivariate analysis techniques were used to quantify and compare the spectral and temporal <span class="hlt">variability</span> of <span class="hlt">observed</span> and simulated shortwave hyperspectral Earth reflectance. The <span class="hlt">observed</span> reflectances were measured by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument between 2002 and 2010. The simulated reflectances were calculated using climate <span class="hlt">Observing</span> System Simulation Experiments (OSSEs), which used two Intergovernmental Panel on Climate Change AR4 scenarios (constant CO2 and A2 emission) to drive Moderate Resolution Atmospheric Transmission simulations. Principal component (PC) spectral shapes and time series exhibited evidence of physical <span class="hlt">variables</span> including cloud reflectance, vegetation and desert albedo, and water vapor absorption. Comparing the temporal <span class="hlt">variability</span> of the OSSE-simulated and SCIAMACHY-measured hyperspectral reflectance showed that their Intertropical Convergence Zone-like Southern Hemisphere (SH) tropical PC1 ocean time series had a 90° phase difference. The <span class="hlt">observed</span> and simulated PC intersection quantified their similarity and directly compared their temporal <span class="hlt">variability</span>. The intersection showed that despite the similar spectral <span class="hlt">variability</span>, the temporal <span class="hlt">variability</span> of the dominant PCs differed as in, for example, the 90° phase difference between the SH tropical intersection PC1s. Principal component analysis of OSSE reflectance demonstrated that the spectral and centennial <span class="hlt">variability</span> of the two cases differed. The A2 PC time series, unlike the constant CO2 time series, exhibited centennial secular trends. Singular spectrum analysis isolated the A2 secular trends. The A2 OSSE PC1 and PC4 secular trends matched those in aerosol optical depth and total column precipitable water, respectively. This illustrates that time series of hyperspectral reflectance may be used to identify and attribute secular climate trends with a sufficiently long measurement record and high instrument accuracy.</p> <div class="credits"> <p class="dwt_author">Roberts, Y. L.; Pilewskie, P.; Feldman, D. R.; Kindel, B. C.; Collins, W. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-09-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_9");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_10");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a style="font-weight: bold;">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_12");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">201</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009EGUGA..11.2630A"> <span id="translatedtitle">The IRIS Data Management Center: Enabling Access to <span class="hlt">Observational</span> Time Series Spanning <span class="hlt">Decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Incorporated Research Institutions for Seismology (IRIS) is funded by the National Science Foundation (NSF) to operate the facilities to generate, archive, and distribute seismological data to research communities in the United States and internationally. The IRIS Data Management System (DMS) is responsible for the ingestion, archiving, curation and distribution of these data. The IRIS Data Management Center (DMC) manages data from more than 100 permanent seismic networks, hundreds of temporary seismic deployments as well as data from other geophysical <span class="hlt">observing</span> networks such as magnetotelluric sensors, ocean bottom sensors, superconducting gravimeters, strainmeters, surface meteorological measurements, and in-situ atmospheric pressure measurements. The IRIS DMC has data from more than 20 different types of sensors. The IRIS DMC manages approximately 100 terabytes of primary <span class="hlt">observational</span> data. These data are archived in multiple distributed storage systems that insure data availability independent of any single catastrophic failure. Storage systems include both RAID systems of greater than 100 terabytes as well as robotic tape robots of petabyte capacity. IRIS performs routine transcription of the data to new media and storage systems to insure the long-term viability of the scientific data. IRIS adheres to the OAIS Data Preservation Model in most cases. The IRIS data model requires the availability of metadata describing the characteristics and geographic location of sensors before data can be fully archived. IRIS works with the International Federation of Digital Seismographic Networks (FDSN) in the definition and evolution of the metadata. The metadata insures that the data remain useful to both current and future generations of earth scientists. Curation of the metadata and time series is one of the most important activities at the IRIS DMC. Data analysts and an automated quality assurance system monitor the quality of the incoming data. This insures data are of acceptably high quality. The formats and data structures used by the seismological community are esoteric. IRIS and its FDSN partners are developing web services that can transform the data holdings to structures that are more easily used by broader scientific communities. For instance, atmospheric scientists are interested in using global <span class="hlt">observations</span> of microbarograph data but that community does not understand the methods of applying instrument corrections to the <span class="hlt">observations</span>. Web processing services under development at IRIS will transform these data in a manner that allows direct use within such analysis tools as MATLAB® already in use by that community. By continuing to develop web-service based methods of data discovery and access, IRIS is enabling broader access to its data holdings. We currently support data discovery using many of the Open Geospatial Consortium (OGC) web mapping services. We are involved in portal technologies to support data discovery and distribution for all data from the EarthScope project. We are working with computer scientists at several universities including the University of Washington as part of a DataNet proposal and we intend to enhance metadata, further develop ontologies, develop a Registry Service to aid in the discovery of data sets and services, and in general improve the semantic interoperability of the data managed at the IRIS DMC. Finally IRIS has been identified as one of four scientific organizations that the External Research Division of Microsoft wants to work with in the development of web services and specifically with the development of a scientific workflow engine. More specific details of current and future developments at the IRIS DMC will be included in this presentation.</p> <div class="credits"> <p class="dwt_author">Ahern, T.; Benson, R.; Trabant, C.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">202</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4198954"> <span id="translatedtitle">Outbreaks of mumps: an <span class="hlt">observational</span> study over two <span class="hlt">decades</span> in a single hospital in Korea</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Purpose The introduction of the mumps vaccine has dramatically reduced the number of mumps cases, but outbreaks have recently occurred among highly vaccinated populations in developed countries. Epidemiological and clinical characteristics of patients with mumps admitted between 1989 and 2012 in a single hospital in Korea are described in the present study. Methods We retrospectively evaluated inpatients with mumps between 1989 and 2012 and outpatients and inpatients with mumps in 2011-2012. Results A total of 152 patients with mumps were admitted between 1989 and 2012, and 163 patients were recorded in 2011-2012. The highest number of admitted cases occurred in 1998 and 2012 (35 and 34 cases, respectively). Among the patients admitted in 2011-2012, the highest frequency was <span class="hlt">observed</span> among people aged 15-19 years, and low frequency was <span class="hlt">observed</span> in those aged <4 years and >20 years, compatible to the city data and national data. In patients admitted to our department in 1998 (35 cases) and in 2010-2012 (27 cases), there were significant differences in the mean age and the rate of secondary measles-mumps-rubella (MMR) vaccination, but had similar clinical features, including complications, except aseptic meningitis. Antimumps immunoglobulin (Ig) G was positive in 83% and 100%, and IgM was positive in 67% and 41%, respectively, in the two periods. Conclusion In Korea, recent mumps outbreaks have occurred mainly among secondary school students who received two doses of the MMR vaccine. The vaccinees might have a modified immune reaction to viral insults, manifesting modified epidemiological and clinical features. PMID:25324865</p> <div class="credits"> <p class="dwt_author">Ryu, Ji-Ung; Kim, Eun-Kyung; Youn, You-Sook; Rhim, Jung-Woo</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">203</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6088S"> <span id="translatedtitle">Trends and <span class="hlt">variability</span> in East African rainfall and temperature <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The economy of East Africa is highly dependent on agriculture, leading to a strong vulnerability of local society to fluctuations in seasonal rainfall amounts, including extreme events. Hence, the knowledge about the evolution of seasonal rainfall under future climate conditions is crucial. Rainfall regimes over East Africa are influenced by multiple factors, including two monsoon systems, several convergence zones and the Rift Valley lakes. In addition, local conditions, like topography, modulate the large-scale rainfall pattern. East African rainfall <span class="hlt">variability</span> is also influenced by various teleconnections like the Indian Ocean Zonal Mode and El Niño Southern Oscillation. Regarding future climate projections, regional and global climate models partly disagree on the increase or decrease of East African rainfall. The specific aim of the present study is the acquirement of historic data from weather stations in East Africa (Kenya, Tanzania, Ruanda and Uganda), the use of gridded satellite (rainfall) products (ARC2 and TRMM), and three-dimensional atmospheric reanalysis (e.g., ERA-Interim) to quantify climate <span class="hlt">variability</span> in the recent past and to understand its causes. Climate <span class="hlt">variability</span> and trends, including changes in extreme events, are evaluated using ETCCDI climate change and standardized precipitation indices. These climate indices are determined in order to investigate the <span class="hlt">variability</span> of temperature and rainfall and their trends with the focus on most recent <span class="hlt">decades</span>. In the follow-up, statistical and dynamical analyses are conducted to quantify the local impact of pertinent large-scale modes of climate <span class="hlt">variability</span> (Indian Ocean Zonal Mode, El Niño Southern Oscillation, Sea Surface Temperature of the Indian Ocean).</p> <div class="credits"> <p class="dwt_author">Seregina, Larisa; Ermert, Volker; Fink, Andreas H.; Pinto, Joaquim G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">204</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20150005603&hterms=climate+change+ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dclimate%2Bchange%2Bocean"> <span id="translatedtitle">MISR <span class="hlt">Decadal</span> <span class="hlt">Observations</span> of Mineral Dust: Property Characterization and Climate Applications</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Multi-angle Imaging SpectroRadiometer (MISR) provides a unique, independent source of data for studying dust emission and transport. MISR's multiple view angles allow the retrieval of aerosol properties over bright surfaces, and such retrievals have been shown to be sensitive to the non-sphericity of dust aerosols over both land and water. MISR stereographic views of thick aerosol plumes allow height and instantaneous wind derivations at spatial resolutions of better than 1.1 km horizontally and 200m vertically. We will discuss the radiometric and stereo-retrieval capabilities of MISR specifically for dust, and demonstrate the use of MISR data in conjunction with other available satellite <span class="hlt">observations</span> for dust property characterization and climate studies.First, we will discuss MISR non-spherical (dust) fraction product over the global oceans. We will show that over the Atlantic Ocean, changes in the MISR-derived non-spherical AOD fraction illustrate the evolution of dust during transport. Next, we will present a MISR satellite perspective on dust climatology in major dust source regions with a particular emphasis on the West Africa and Middle East and discuss MISR's unique strengths as well as current product biases. Finally, we will discuss MISR dust plume product and climatological applications.</p> <div class="credits"> <p class="dwt_author">Kalashnikova, Olga V.; Garay, Michael J.; Sokolik, Irina; Kahn, Ralph A.; Lyapustin, A.; Diner, David J.; Lee, Jae N.; Torres, Omar; Leptoukh, Gregory G.; Sabbah, Ismail</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">205</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2911134"> <span id="translatedtitle">Religious education and midlife <span class="hlt">observance</span> are associated with dementia three <span class="hlt">decades</span> later in Israeli men</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Objective The aim of the study was to examine the association of religious education and <span class="hlt">observance</span> with dementia among participants in the Israeli Ischemic Heart Disease study. Study Design and Setting We assessed dementia in 1,890 participants among 2,604 survivors of 10,059 participants in the Israeli Ischemic Heart Disease study, a longitudinal investigation of the incidence and risk factors for cardiovascular disease among Jewish male civil servants in Israel. Face-to-face interviews were conducted with 651 subjects identified as possibly demented by the Modified Telephone Interview for Cognitive Status. Results Of 1,628 subjects included in this analysis (mean age 82 at assessment), 308 (18.9%) had dementia. The prevalence rates of dementia (and odds ratios (ORs) relative to those with exclusively religious education, adjusted for age, area of birth, and socioeconomic status) were 27.1% for those with exclusively religious education, 12.6% (OR=0.49) for those with mixed education, and 16.1% (OR=0.76) for those with secular education. For religious self-definition and practice, the prevalence rates were 9.7%, 17.7%, 14.1%, 19.3%, and 28.8% for categories from least to most religious (ORs relative to the most religious: 0.43, 0.67, 0.48, 0.55). Conclusions Examining lifestyles associated with religiosity might shed light onto environmental risks for dementia. Mechanisms underlying these associations remain elusive. PMID:18538995</p> <div class="credits"> <p class="dwt_author">Beeri, Michal Schnaider; Davidson, Michael; Silverman, Jeremy M.; Schmeidler, James; Springer, Ramit Ravona; Noy, Shlomo; Goldbourt, Uri</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">206</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22167329"> <span id="translatedtitle">A <span class="hlt">DECADE</span> OF SOLAR TYPE III RADIO BURSTS <span class="hlt">OBSERVED</span> BY THE NANCAY RADIOHELIOGRAPH 1998-2008</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We present a statistical survey of almost 10,000 radio type III bursts <span class="hlt">observed</span> by the Nancay Radioheliograph from 1998 to 2008, covering nearly a full solar cycle. In particular, sources sizes, positions, and fluxes were examined. We find an east-west asymmetry in source positions that could be attributed to a 6 Degree-Sign {+-} 1 Degree-Sign eastward tilt of the magnetic field, that source FWHM sizes s roughly follow a solar-cycle-averaged distribution (dN/ds) Almost-Equal-To 14 {nu}{sup -3.3} s {sup -4} arcmin{sup -1} day{sup -1}, and that source fluxes closely follow a solar-cycle-averaged (dN/ds {sub {nu}}) Almost-Equal-To 0.34 {nu}{sup -2.9} S {sup -1.7} {sub {nu}} sfu{sup -1} day{sup -1} distribution (when {nu} is in GHz, s in arcminutes, and S {sub {nu}} in sfu). Fitting a barometric density profile yields a temperature of 0.6 MK, while a solar wind-like ({proportional_to}h {sup -2}) density profile yields a density of 1.2 Multiplication-Sign 10{sup 6} cm{sup -3} at an altitude of 1 R{sub S} , assuming harmonic emission. Finally, we found that the solar-cycle-averaged radiated type III energy could be similar in magnitude to that radiated by nanoflares via non-thermal bremsstrahlung processes, and we hint at the possibility that escaping electron beams might carry as much energy away from the corona as is introduced into it by accelerated nanoflare electrons.</p> <div class="credits"> <p class="dwt_author">Saint-Hilaire, P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)] [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Vilmer, N.; Kerdraon, A., E-mail: shilaire@ssl.berkeley.edu [LESIA, Observatoire de Paris, CNRS, UPMC, Universite Paris-Diderot 5 place Jules Janssen, F-92195 Meudon (France)</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">207</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFM.P23A1922P"> <span id="translatedtitle"><span class="hlt">Observational</span> Evidence for a <span class="hlt">Decade</span>-long climate optimum near the Hesperian/Amazonian Transition</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Hesperian to Amazonian-aged valleys (HAVs) are predominantly found in the southern equatorial and mid-latitudes of Mars and form parallel to dendritic networks. These features record a significant warming of the regional/global climate which may have been associated with outflow channel formation and/or a period of alluvial fan deposition in Margaritifer Terra [1]. HAVs are distinct from older valley networks in both their age and morphology and they provide a window into the past climate conditions and potential water sources which formed them. Using quantitative geomorphic analysis we calculate the expected range of timescales, water volumes, precipitation rates and atmospheric conditions which contributed to HAV formation. In Newton crater (40oS, -159oE) we measured valley widths, depths, slopes and alluvial fan volumes. These <span class="hlt">observations</span>, when combined with a set of terrestrial sediment transport prediction functions [2,3,4,5], allow us to calculate an expected duration of fluvial activity ranging from 0.1 to 10 years for water-filled channel depths ranging between 20 and 130 cm, and median sediment grain size ranging from 1 mm to 10 cm. The water volume required to form a single HAV in Newton crater ranges between 1.8 and 5.7~km3 based on the Darcy-Weisbach equation [6] in combination with the aforementioned range in channel depths, grain sizes and formation timescales. These results imply water runoff rates of between 1 to 10~cm/day over a typical, 300~km2, drainage area. Such a high runoff rate and short formation time suggest a brief, dramatic regional to global climate excursion. The source of water which formed these features remains unclear, but it must have been released at the aforementioned rates, and was widely distributed within each drainage catchment, and regionally over Newton crater and the southern highlands. HAV formation was likely a two-step process involving, first, the deposition of a 10s of meters thick regional snowpack along topographic highs sourced either from polar ice redistributed during high obliquity, or by one or more outflow channel water release events. The atmospheric temperature gradient required to generate preferential ice deposition on topographic highs implies a much thicker (few hundred millibars [7]) atmosphere. Next, a significant (perhaps, brief) global warming event melted these snowpacks. Likely warming mechanisms include the formation of a ~100 km impact crater or a short-lived SO2 greenhouse generated from a rapid, voluminous volcanic dike injection such as that which formed Sirenum Fossae [8]. [1] Grant, J., & Wilson, S. (2011), Geophys. Res. Lett., 38. [2] Smart, G. (1984), J. Hydraulic Eng., 110, 267-276. [3] Meyer-Peter, E. & Mueller, R. (1948) in Int. Assoc. for Hydraul. Struct. Res., vol. 2, pp. 39-64, Stockholm. [4] Parker, G., Klingeman, P. & McLean, D. (1982) J. Hydraul. Eng., 108(HY4), 544-571. [5] Ribberink, J. S. (1998), Coastal Eng., 34, 59-82. [6] Silberman, E., Einstein, H., Hinds, J., Powell, R., et al. (1963), J. Hydraul. Eng., 89(HY2), 97-143. [7] Wordsworth, R., Forget, F., Millour, E., Head, J., Madeleine, J.-B. & Charnay, B. (submitted), Icarus. [8] Wilson, L., & Head, J. (2002), J. Geophys. Res., 107.</p> <div class="credits"> <p class="dwt_author">Parsons, R.; Moore, J. M.; Howard, A. D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">208</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.po.gso.uri.edu/dynamics/publications/os_2008/OSM2008_JHPark.pdf"> <span id="translatedtitle">Sea Surface Height <span class="hlt">Variability</span> <span class="hlt">Observed</span> by Pressure-recording Inverted</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Sea Surface Height <span class="hlt">Variability</span> <span class="hlt">Observed</span> by Pressure-recording Inverted Echo Sounders and Satellite echo sounders (PIESs) 7 moored profilers 48 profiling floats 1 moored surface buoy (KEO buoy) #12;03/07/08 Park/URI 3 PIES (Pressure-recording Inverted Echo Sounder) Emits 12 kHz sound pulses Measures - round</p> <div class="credits"> <p class="dwt_author">Rhode Island, University of</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">209</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://clclinic.cos.ucf.edu/Documents%20and%20Files/Rapport%20Kofler%20Alderson%20Timko%20&%20DuPaul%20Variability%20of%20Attention%20Processes%20in%20ADHD.pdf"> <span id="translatedtitle"><span class="hlt">Variability</span> of Attention Processes in ADHD: <span class="hlt">Observations</span> From the Classroom</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Objective: Classroom- and laboratory-based efforts to study the attentional problems of children with ADHD are incongru- ent in elucidating attentional deficits; however, none have explored within- or between-minute <span class="hlt">variability</span> in the classroom attentional processing in children with ADHD. Method: High and low attention groups of ADHD children defined via clus- ter analysis, and 36 typically developing children, are <span class="hlt">observed</span> while</p> <div class="credits"> <p class="dwt_author">Mark D. Rapport; Michael J. Kofler; R. Matt Alderson; Thomas M. Timko; G. J. DuPaul</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">210</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19990064613&hterms=parkinsons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dparkinsons"> <span id="translatedtitle"><span class="hlt">Variability</span> of Arctic Sea Ice as Determined from Satellite <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The compiled, quality-controlled satellite multichannel passive-microwave record of polar sea ice now spans over 18 years, from November 1978 through December 1996, and is revealing considerable information about the Arctic sea ice cover and its <span class="hlt">variability</span>. The information includes data on ice concentrations (percent areal coverages of ice), ice extents, ice melt, ice velocities, the seasonal cycle of the ice, the interannual <span class="hlt">variability</span> of the ice, the frequency of ice coverage, and the length of the sea ice season. The data reveal marked regional and interannual <span class="hlt">variabilities</span>, as well as some statistically significant trends. For the north polar ice cover as a whole, maximum ice extents varied over a range of 14,700,000 - 15,900,000 sq km, while individual regions experienced much greater percent variations, for instance, with the Greenland Sea having a range of 740,000 - 1,110,000 sq km in its yearly maximum ice coverage. In spite of the large variations from year to year and region to region, overall the Arctic ice extents showed a statistically significant, 2.80% / <span class="hlt">decade</span> negative trend over the 18.2-year period. Ice season lengths, which vary from only a few weeks near the ice margins to the full year in the large region of perennial ice coverage, also experienced interannual <span class="hlt">variability</span>, along with spatially coherent overall trends. Linear least squares trends show the sea ice season to have lengthened in much of the Bering Sea, Baffin Bay, the Davis Strait, and the Labrador Sea, but to have shortened over a much larger area, including the Sea of Okhotsk, the Greenland Sea, the Barents Sea, and the southeastern Arctic.</p> <div class="credits"> <p class="dwt_author">Parkinson, Claire L.</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">211</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19770053166&hterms=variables+STAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dvariables%2BSTAR"> <span id="translatedtitle">Characteristics of IR <span class="hlt">variable</span> stars as <span class="hlt">observed</span> from orbit</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A selection of infrared <span class="hlt">variable</span> stars was studied at wavelength 2.7 microns during 1971-1975 with data from U.S. Air Force satellites. Stars <span class="hlt">observed</span> in this program are classified as long-period <span class="hlt">variable</span> stars, semiregular <span class="hlt">variables</span>, and irregular <span class="hlt">variables</span> and are among the strongest stellar sources at this wavelength. In addition, a few new, as yet unclassified <span class="hlt">variable</span> stars were identified during the course of the investigation. Time scales of reproducible variations range from a few weeks to a few years, and amplitudes of variation are as large as a factor of three for stars with periods of order one year. The minimum infrared flux density of a long-period star repeats accurately from one cycle to the next, whereas the maximum flux density was found to be unstable. The correlation of 2.7 micron and radio emission line data from one, well-studied long-period <span class="hlt">variable</span> is consistent with the hypothesis that the H2O and OH circumstellar masers are saturated, if pumped by the stellar infrared flux near 2.7 microns.</p> <div class="credits"> <p class="dwt_author">Maran, S. P.; Heinsheimer, T. F.; Stocker, T. L.; Chapman, R. D.; Hobbs, R. W.; Michalitsanos, A. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">1976-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">212</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/1994Ap%26SS.221..197S"> <span id="translatedtitle">Simultaneous optical and ultraviolet <span class="hlt">observations</span> of <span class="hlt">variability</span> in HD 50896</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In this paper, simultaneous optical and ultraviolet <span class="hlt">observations</span> of spectral <span class="hlt">variability</span> of the WN5 star HD 50896 are presented. Night-to-night and shorter timescale changes were found in the shape and intensity of most emission lines and P Cygni profiles in both wavelength ranges but there is no clear link between the ultraviolet and optical <span class="hlt">variability</span>. There are some indications that the ultraviolet variations occur in phase with the well-known 3.766-day period often associated with this star.</p> <div class="credits"> <p class="dwt_author">St-Louis, Nicole</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">213</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMPP24A..04D"> <span id="translatedtitle">Evolution of Interannual and <span class="hlt">Decadal</span>/Interdecadal <span class="hlt">variability</span> of the SPCZ since the late 18th century using a network of Fiji coral ?18O time-series</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The South Pacific Convergence Zone (SPCZ) region is of high interest due to its impact on tropical rainfall and the export of moisture from the tropics. Documenting the amplitude and periodicity of SPCZ displacements on interannual (mainly influenced by El Niño Southern Oscillation (ENSO)) and <span class="hlt">decadal</span>/interdecadal (D/I) time-scales is of high importance not only for risk management but also for understanding the dynamics of the SPCZ and for improving General Circulation Model climate predictions. We have generated a unique regional coral ?18O network from the Fiji Islands, which are located just south of the main SPCZ rainfall axis. This network consists of five monthly-resolved coral ?18O time-series from different regions of Fiji. Evaluation of interseries correlation coefficients indicates that ENSO-band (2 to 9 years) and D/I-band (10 to 50 years) ?18O <span class="hlt">variability</span> is highly reproducible. Correlation to instrumental surface salinity (SSS) data indicates that interannual coral ?18O <span class="hlt">variability</span> in Fiji is the result of interannual changes in SSS that are coupled to ENSO. The composite reconstruction (arithmetic average of the five Fiji ?18O records), extending from 1790 to 2004 AD, was compared to known climatic indices such as the Southern Oscillation and Interdecadal Pacific Oscillation indices over the 20th century. Pearson Product-Moment correlations between the coral ?18O composite and these target indices of the Pacific basin are r= 0.71 and 0.41 for ENSO and D/I timescales respectively, with p-values better than 0.001. These high values indicate that our Fiji composite ?18O record is suitable for reconstructing past ENSO and D/I <span class="hlt">variability</span> prior to the instrumental record. Our Fiji ENSO-band and D/I-band reconstructions from the Southwest Pacific also share important similarities with other Pacific coral ?18O records such as the ?18O record from Malo-Channel (Vanuatu). The Fiji composite ?18O reconstruction also correlates negatively with interannual and D/I coral ?18O <span class="hlt">variability</span> from equatorial sites in the Pacific (e.g. Maiana). Collectively, our results from the SPCZ region reflect the validity of the coral ?18O composite to track regional climatic <span class="hlt">variability</span> at both interannual and <span class="hlt">decadal</span>/interdecadal timescales. From the late 18th century to the late 19th century the D/I band dominates the Fiji composite while the ENSO-band amplitude is relatively small. Starting around 1885, this tendency reverses and we <span class="hlt">observed</span> a drastic decrease in the D/I signal amplitude, with its variance reduced by more than 50%, while the ENSO-band signal increases progressively in amplitude toward the present, reaching unprecedented values during the mid-20th century. This switch around 1885 A.D. is unique over the last 250 years and may correspond to a reorganization of Pacific-wide climate.</p> <div class="credits"> <p class="dwt_author">Dassie, E. P.; Linsley, B. K.; Correge, T.; Wu, H. C.; Lemley, G. M.; Cabioch, G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">214</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23996901"> <span id="translatedtitle">Reassessing regime shifts in the North Pacific: incremental climate change and commercial fishing are necessary for explaining <span class="hlt">decadal</span>-scale biological <span class="hlt">variability</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">In areas of the North Pacific that are largely free of overfishing, climate regime shifts - abrupt changes in modes of low-frequency climate <span class="hlt">variability</span> - are seen as the dominant drivers of <span class="hlt">decadal</span>-scale ecological <span class="hlt">variability</span>. We assessed the ability of leading modes of climate <span class="hlt">variability</span> [Pacific <span class="hlt">Decadal</span> Oscillation (PDO), North Pacific Gyre Oscillation (NPGO), Arctic Oscillation (AO), Pacific-North American Pattern (PNA), North Pacific Index (NPI), El Niño-Southern Oscillation (ENSO)] to explain <span class="hlt">decadal</span>-scale (1965-2008) patterns of climatic and biological <span class="hlt">variability</span> across two North Pacific ecosystems (Gulf of Alaska and Bering Sea). Our response <span class="hlt">variables</span> were the first principle component (PC1) of four regional climate parameters [sea surface temperature (SST), sea level pressure (SLP), freshwater input, ice cover], and PCs 1-2 of 36 biological time series [production or abundance for populations of salmon (Oncorhynchus spp.), groundfish, herring (Clupea pallasii), shrimp, and jellyfish]. We found that the climate modes alone could not explain ecological <span class="hlt">variability</span> in the study region. Both linear models (for climate PC1) and generalized additive models (for biology PC1-2) invoking only the climate modes produced residuals with significant temporal trends, indicating that the models failed to capture coherent patterns of ecological <span class="hlt">variability</span>. However, when the residual climate trend and a time series of commercial fishery catches were used as additional candidate <span class="hlt">variables</span>, resulting models of biology PC1-2 satisfied assumptions of independent residuals and out-performed models constructed from the climate modes alone in terms of predictive power. As measured by effect size and Akaike weights, the residual climate trend was the most important <span class="hlt">variable</span> for explaining biology PC1 <span class="hlt">variability</span>, and commercial catch the most important <span class="hlt">variable</span> for biology PC2. Patterns of climate sensitivity and exploitation history for taxa strongly associated with biology PC1-2 suggest plausible mechanistic explanations for these modeling results. Our findings suggest that, even in the absence of overfishing and in areas strongly influenced by internal climate <span class="hlt">variability</span>, climate regime shift effects can only be understood in the context of other ecosystem perturbations. PMID:23996901</p> <div class="credits"> <p class="dwt_author">Litzow, Michael A; Mueter, Franz J; Hobday, Alistair J</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">215</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.springerlink.com/index/0819r76851376012.pdf"> <span id="translatedtitle">Bi-<span class="hlt">decadal</span> <span class="hlt">variability</span> excited in the coupled ocean–atmosphere system by strong tropical volcanic eruptions</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary"><span class="hlt">Decadal</span> and bi-<span class="hlt">decadal</span> climate responses to tropical strong volcanic eruptions (SVEs) are inspected in an ensemble simulation\\u000a covering the last millennium based on the Max Planck Institute—Earth system model. An unprecedentedly large collection of\\u000a pre-industrial SVEs (up to 45) producing a peak annual-average top-of-atmosphere radiative perturbation larger than ?1.5 Wm?2 is investigated by composite analysis. Post-eruption oceanic and atmospheric anomalies coherently</p> <div class="credits"> <p class="dwt_author">D. Zanchettin; C. Timmreck; H.-F. Graf; A. Rubino; S. Lorenz; K. Lohmann; K. Krüger; J. H. Jungclaus</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">216</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/10193764"> <span id="translatedtitle">Dynamics and <span class="hlt">variability</span> of the plasmasphere <span class="hlt">observed</span> from synchronous orbit</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The behavior of the cold ions in the outer plasmasphere is studied using data obtained with the magnetospheric plasma analyzers from multiple geosynchronous satellites. Dense (10-100 cm{sup {minus}3}), cold ({approx}1 eV) regions of plasma are often <span class="hlt">observed</span> at geosynchronous orbit; in this study the authors refer to these as plasmaspheric intervals. The duration, local time of <span class="hlt">observation</span>, density <span class="hlt">variability</span>, and temperature behavior within these regions often depend in a systematic way on geomagnetic and substorm activity. With increasing geomagnetic activity (as indicated by Kp) the plasmaspheric regions are generally <span class="hlt">observed</span> over shorter durations and at earlier local times. With increasing substorm activity (as indicated by geosynchronous energetic electron injections) the density becomes increasingly <span class="hlt">variable</span> in these regions. Occasionally, up to order-of-magnitude density variations are <span class="hlt">observed</span> over several minute timescales corresponding to regions with physical dimensions on the order of 1000 km or less. The appearance of these short-duration, cold-plasma intervals is strongly correlated with energetic ion and electron signatures both at the spacecraft making the plasmaspheric <span class="hlt">observations</span> and at other spacecraft <span class="hlt">observing</span> simultaneously in the midnight region. Such energetic particle signatures are indicative of the growth and expansive phase of geomagnetic substorms. The authors conclude that the appearance of these short-duration, plasmaspheric intervals is due to a reconfiguration of the duskside magnetosphere during geomagnetic substorms.</p> <div class="credits"> <p class="dwt_author">Moldwin, M.B.; Thomsen, M.F.; McComas, D.J.; Reeves, G.D.</p> <p class="dwt_publisher"></p> <p class="publishDate">1994-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">217</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AAN...471....1W"> <span id="translatedtitle">Cataclysmic <span class="hlt">variables</span> to be monitored for HST <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Drs. Boris Gaensicke (Warwick University), Joseph Patterson (Columbia University, Center for Backyard Astrophysics), and Arne Henden (AAVSO), on behalf of a consortium of 16 astronomers, requested the help of AAVSO <span class="hlt">observers</span> in monitoring the ~40 cataclysmic <span class="hlt">variables</span> in support of Hubble Space Telescope <span class="hlt">observations</span> in the coming months. The HST COS (Cosmic Origins Spectrograph) will be carrying out far-ultraviolet spectroscopy of ~40 CVs sequentially, with the aim to measure the temperatures, atmospheric compositions, rotation rates, and eventually masses of their white dwarfs. The primary purpose of the monitoring is to know whether each target is in quiescence immediately prior to the <span class="hlt">observation</span> window; if it is in outburst it will be too bright for the HST instrumentation. Based on the information supplied by the AAVSO, the HST scheduling team will make the decision (usually) the evening before the scheduled <span class="hlt">observing</span> time as to whether to go forward with the HST <span class="hlt">observations</span>. For CCD <span class="hlt">observers</span>, simultaneous photometry [shortly before, during, and after the HST <span class="hlt">observations</span>] would be ideal. B filter would be best for a light curve, although for the magnitude estimates, V would be best. Finder charts may be created using the AAVSO <span class="hlt">Variable</span> Star Plotter (http://www.aavso.org/vsp). <span class="hlt">Observations</span> should be submitted to the AAVSO International Database. If the target is seen in outburst, please contact the AAVSO immediately and post a message to the <span class="hlt">Observations</span> and Campaigns & <span class="hlt">Observations</span> Reports forum (http://www.aavso.org/forum). This campaign will run the better part of a year or longer. See full Alert Notice for more details and list of objects.</p> <div class="credits"> <p class="dwt_author">Waagen, Elizabeth O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">218</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012JAVSO..40...24B"> <span id="translatedtitle">Anne S. Young: Professor and <span class="hlt">Variable</span> Star <span class="hlt">Observer</span> Extraordinaire</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">One of the original eight members of the AAVSO, but not well known today, was Professor Anne Sewell Young of Mount Holyoke College. Miss Young taught there for thirty-seven years, and trained many women astronomers during the first third of the 20th century. This paper will attempt to present her life as an inspiring teacher, as well as a contributor of more than 6,500 <span class="hlt">variable</span> star <span class="hlt">observations</span> to the AAVSO.</p> <div class="credits"> <p class="dwt_author">Bracher, K.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">219</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AGUFM.A13E0273T"> <span id="translatedtitle">Linking July Sea Ice Concentration Anomalies in Hudson Bay to Inter-annual and Multi-<span class="hlt">decadal</span> <span class="hlt">Variability</span> of North Atlantic Sea Surface Temperatures</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A new atmospheric teleconnection pathway is presented that links <span class="hlt">variability</span> in fall North Atlantic sea surface temperatures (SST) to sea ice concentration (SIC) anomalies in Hudson Bay the following July. The loss of summer sea ice cover in Hudson Bay over the past three <span class="hlt">decades</span> is amongst the greatest of any region in the Northern Hemisphere (~20% per <span class="hlt">decade</span>). Identifying links between SIC in this region to large-scale climate <span class="hlt">variability</span> could yield insight into the potential cause of this dramatic decline. Co-<span class="hlt">variability</span> between July SIC data from the Canadian Ice Service regional ice charts and North Atlantic SST data from HadISST1.1, is explored over the 1971 to 2005 period using Canonical Correlation Analysis. An atmospheric teleconnection pathway is elucidated by correlating the dominant canonical correlation time-series with atmospheric data from the NCEP Reanalysis project. It is found that 54% of the <span class="hlt">variability</span> in July SIC is explained by fall SST anomalies in the North Atlantic. A strengthening (weakening) of the climatological ridge in 850mb north-west of Hudson Bay during winter, in response to fall North Atlantic SST anomalies, enhances (weakens) the dominant northwesterly winds that keep ice thin along the northern coast of Hudson Bay and Hudson Strait and advect cold air over the rest of the bay promoting ice growth. The resulting winter anomalies in ice thickness manifest as SIC anomalies in July. An interesting implication of the teleconnection pathway identified in this study is that if the multi-<span class="hlt">decadal</span> signal in North Atlantic SST, known as the Atlantic Multi-<span class="hlt">decadal</span> Oscillation (AMO), returns to a cool phase there could be some recovery in early summer sea ice cover in Hudson Bay.</p> <div class="credits"> <p class="dwt_author">Tivy, A.; Howell, S.; Yackel, J.; Carrieres, T. G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">220</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20010015246&hterms=surface+area&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dsurface%2Barea"> <span id="translatedtitle">Satellite <span class="hlt">Observed</span> <span class="hlt">Variability</span> in Antarctic and Arctic Surface Temperatures and Their Correlation to Open Water Areas</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Recent studies using meterological station data have indicated that global surface air temperature has been increasing at a rate of 0.05 K/<span class="hlt">decade</span>. Using the same set of data but for stations in the Antarctic and Arctic regions (>50 N) only, the increases in temperature were 0.08, and 0.22 K/<span class="hlt">decade</span>, when record lengths of 100 and 50 years, respectively, were used. To gain insights into the increasing rate of warming, satellite infrared and passive microwave <span class="hlt">observations</span> over the Arctic region during the last 20 years were processed and analyzed. The results show that during this period, the ice extent in the Antarctic has been increasing at the rate of 1.2% per <span class="hlt">decade</span> while the surface temperature has been decreasing at about 0.08 K per <span class="hlt">decade</span>. Conversely, in the Northern Hemisphere, the ice extent has been decreasing at a rate of 2.8% per <span class="hlt">decade</span>, while the surface temperatures have been increasing at the rate of 0.38 K per <span class="hlt">decade</span>. In the Antarctic, it is surprising that there is a short term trend of cooling during a global period of warming. Very large anomalies in open water areas in the Arctic were <span class="hlt">observed</span> especially in the western region, that includes the Beaufort Sea, where the <span class="hlt">observed</span> open water area was about 1x10(exp 6) sq km, about twice the average for the region, during the summer of 1998. In the eastern region, that includes the Laptev Sea, the area of open water was also abnormally large in the summer of 1995. Note that globally, the warmest and second warmest years in this century, were 1998 and 1995, respectively. The data, however, show large spatial <span class="hlt">variability</span> with the open water area distribution showing a cyclic periodicity of about ten years, which is akin to the North Atlantic and Arctic Oscillations. This was <span class="hlt">observed</span> in both western and eastern regions but with the phase of one lagging the other by about two years. This makes it difficult to interpret what the trends really mean. But although the record length of satellite data is still relatively short and the climate trend difficult to establish, the immediate impact of a continued warming trend may be very profound.</p> <div class="credits"> <p class="dwt_author">Comiso, Josefino C.; Zukor, Dorothy (Technical Monitor)</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_10");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" 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onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a style="font-weight: bold;">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_13");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">221</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20010111482&hterms=stars+work&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dstars%2Bwork"> <span id="translatedtitle">Constraints on <span class="hlt">Variability</span> of Brightness and Surface Magnetism on Time Scales of <span class="hlt">Decades</span> to Centuries in the Sun and Sun-Like Stars: A Source of Potential Terrestrial Climate <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">These four points summarize our work to date. (1) Conciliation of solar and stellar photometric <span class="hlt">variability</span>. Previous research by us and colleagues suggested that the Sun might at present be showing unusually low photometric <span class="hlt">variability</span> compared to other sun-like stars. Those early results would question the suitability of the technique of using sun-like stars as proxies for solar irradiance change on time scales of <span class="hlt">decades</span> to centuries. However, our results indicate the contrary: the Sun's <span class="hlt">observed</span> short-term (seasonal) and longterm (year-to-year) brightness variations closely agree with <span class="hlt">observed</span> brightness variations in stars of similar mass and age. (2) We have demonstrated an inverse correlation between the global temperature of the terrestrial lower troposphere, inferred from the NASA Microwave Sounding Unit (MSU) radiometers, and the total area of the Sun covered by coronal holes from January 1979 to present (up to May 2000). <span class="hlt">Variable</span> fluxes of either solar charged particles or cosmic rays, or both, may influence the terrestrial tropospheric temperature. The geographical pattern of the correlation is consistent with our interpretation of an extra-terrestrial charged particle forcing. (3) Possible climate mechanism amplifying the impact of solar ultraviolet irradiance variations. The key points of our proposed climate hypersensitivity mechanism are: (a) The Sun is more <span class="hlt">variable</span> in the UV (ultraviolet) than in the visible. However, the increased UV irradiance is mainly absorbed in the lower stratosphere/upper troposphere rather than at the surface. (b) Absorption in the stratosphere raises the temperature moderately around the vicinity of the tropopause, and tends to stabilize the atmosphere against vertical convective/diffusive transport, thus decreasing the flux of heat and moisture carried upward from surface. (c) The decrease in the upward convection of heat and moisture tends to raise the surface temperature because a drier upper atmosphere becomes less cloudy, which in turn allows more solar radiation to reach the Earth's surface. (4) Natural <span class="hlt">variability</span> in an ocean-atmosphere climate model. We use a 14-region, 6-layer, global thermo-hydrodynamic ocean-atmosphere model to study natural climate <span class="hlt">variability</span>. All the numerical experiments were performed with no change in the prescribed external boundary conditions (except for the seasonal cycle of the Sun's tilt angle). Therefore, the <span class="hlt">observed</span> inter-annual <span class="hlt">variability</span> is of an internal kind. The model results are helpful toward the understanding of the role of nonlinearity in climate change. We have demonstrated a range of possible climate behaviors using our newly developed ocean-atmosphere model. These include climate configurations with no interannual <span class="hlt">variability</span>, with multi-year periodicities, with continuous chaos, or with chaotically occuring transitions between two discrete substrates. These possible modes of climate behavior are all possible for the real climate, as well as the model. We have shown that small temporary climate influences can trigger shifts both in the mean climate, and among these different types of behavior. Such shifts are not only theoretically plausible, as shown here and elsewhere; they are omnipresent in the climate record on time scales from several years to the age of the Earth. This has two apparently opposite implications for the possibility of anthropogenic global warming. First, any warming which might occur as a result of human influence would be only a fraction of the small-to-large unpredictable natural changes and changes which result from other external causes. On the other hand, small temporary influences such as human influence do have the potential of causing large permanent shifts in mean climate and interannual <span class="hlt">variability</span>.</p> <div class="credits"> <p class="dwt_author">Baliunas, Sallie L.; Sharber, James (Technical Monitor)</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">222</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.6819S"> <span id="translatedtitle"><span class="hlt">Decadal</span> to millennial-scale <span class="hlt">variability</span> in sea ice, primary productivity, and Pacific-Water inflow in the Chukchi/East Siberian Sea area (Arctic Ocean)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Sea-ice is an essential component of the global climate system and, especially, the Polar Oceans. An alarming decrease in term of sea-ice concentration, thickness and duration, has been <span class="hlt">observed</span> in the Arctic Ocean and its marginal seas over the last 30 years. Thus, understanding the processes controlling modern sea-ice <span class="hlt">variability</span> and reconstructing paleo-sea-ice extent and <span class="hlt">variability</span> in polar regions have become of great interest for the international scientific community during the last years. Here, we present new proxy records determined in sediment cores from the East Siberian Sea (RV Polarstern Expedition ARK-XXIII/3 in 2008; Core PS72/350) and from the Chukchi Sea (RV Araon Expedition ARA2B in 2011; Core ARA2B-1A, -1B). These records, including organic-geochemical bulk parameters, specific biomarkers (IP25 and sterols; PIP25; for recent reviews see Stein et al., 2012; Belt and Müller, 2013), biogenic opal, mineralogical data as well as high-resolution XRF scanning data, give new insight into the short-term (<span class="hlt">decadal</span>-, centennial- to millennial-scale) <span class="hlt">variability</span> in sea-ice, primary productivity and Pacific-Water inflow during Holocene times. Maximum concentrations of phytoplankton biomarkers and biogenic opal were determined between 8.5 and 4 kyrs. BP, suggesting enhanced primary productivity triggered by increased inflow of nutrient-rich Pacific Water (and/or an increased nutrient input due to an ice-edge position). Short-lived peak values in productivity might be related to strong pulses of Pacific-Water input during this time period (cf., Ortiz et al., 2009). A seasonal sea-ice cover was present in the Chukchi Sea throughout the last 10 kyrs. During the last 3-4 kyrs. BP, the sea-ice cover significantly extended. References Belt, S.T. and Müller, J., 2013. The Arctic sea ice biomarker IP25: a review of current understanding, recommendations for future research and applications in palaeo sea ice reconstructions. Quaternary Science Review 73, 9-25. Ortiz, J. D., Polyak, L., Grebmeier, J. M., Darby, D., Eberl D. D., Naidu, S., Nof, D., 2009. Provenance of Holocene sediment on the Chukchi-Alaskan margin based on combined diffuse spectral reflectance and quantitative X-Ray Diffraction analysis. Global and Planetary Change 68, pp.73-84. Stein, R., Fahl, K., and Müller, J., 2012. Proxy Reconstruction of Cenozoic Arctic Ocean Sea-Ice History - from IRD to IP25. Polarforschung 82, 37-71.</p> <div class="credits"> <p class="dwt_author">Stein, Ruediger; Fahl, Kirsten; Matthiessen, Jens; Méheust, Marie; Nam, Seung-il; Niessen, Frank; Schade, Inka; Schreck, Michael; Wassmuth, Saskia; Xiao, Xiaotong</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">223</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMPP51C..02Y"> <span id="translatedtitle"><span class="hlt">Decadal</span>- and Centennial-Scale <span class="hlt">Variability</span> in Sea Surface Temperature in Beppu Bay in Japan During the Last 2900 Years</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We generated 8-year-resolution records of paleotemperatures using UK37? and TEX86 and discuss the <span class="hlt">decadal</span> and centennial changes in winter and summer sea surface temperatures (SSTs) in Beppu Bay, Kyushu Island, Japan. Beppu Bay is a silled basin filled with oxygen-deficient bottom water. Because of anoxic environment, organic matter is well preserved in sediments and bioturbation is limited. Fourteen piston and gravity cores were retrieved at the center of the basin. Correlation of cores was conducted using sand and silt seams, and the age-depth model was created by wiggle-matching of forty-two AMS radiocarbon dates from bivalve mollusk shells and excess Pb-210 and Cs-137 concentrations. The sedimentation rates were 230-300 cm/ky. TEX86 and UK37? records show different patterns, but both have a similar multi-<span class="hlt">decadal</span> periodicity. The temperature estimated by TEX86 at the core-top sample is lower than mean annual SST, implying that TEX86 reflects the SST weighted in winter. That by UK37? corresponds to the SST weighted in summer. UK37? shows multi-<span class="hlt">decadal</span> and centennial-scale variation interrupted by frequent short-term cool periods. The periods corresponded to volcanic eruptions recorded in a Greenland ice core. TEX86 shows multi-<span class="hlt">decadal</span> variation that is consistent with a proxy PDO record reconstructed from North American tree-rings. Beppu Bay sediments are a good climate archive to provide high-resolution summer and winter SST records in the northwestern Pacific region.</p> <div class="credits"> <p class="dwt_author">Yamamoto, M.; Kuwae, M.; Abe, M.; Ichikawa, N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">224</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.A41C0074W"> <span id="translatedtitle">Analysis of Marine Stratocumulus Drizzle <span class="hlt">Variability</span> Using In Situ <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Precipitation is an important factor in the dynamics and large-scale organization of marine stratocumulus, yet it remains poorly understood. We aim to elucidate the factors driving the amount and <span class="hlt">variability</span> of marine stratocumulus drizzle using in situ <span class="hlt">observations</span>. We use aircraft measurements from two regions: a) in the near-coastal region of Monterey, CA during the Physics of Stratocumulus Top (POST) project from July and August 2008 and b) in the near-coastal region of Iquique, Chile during the VAMOS Ocean-Cloud-Atmosphere-Land Study (VOCALS) from October 2008. Using these two different projects, we examine whether or not changes in conditions such as boundary layer depth, cloud top liquid water content, aerosol or drop concentrations, turbulence strength and inversion strength affect drizzle amount and <span class="hlt">variability</span>. Interpreting which of these factors tend to associate most closely with various measures of drizzle intensity and <span class="hlt">variability</span> will give insight into processes relevant to both precipitation formation and maintenance, and hopefully help explain how stratocumulus organize into the large-scale cellular patterns <span class="hlt">observed</span>.</p> <div class="credits"> <p class="dwt_author">Witte, M.; Chuang, P. Y.; Rossiter, D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">225</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/54276887"> <span id="translatedtitle"><span class="hlt">Decadal</span>-scale <span class="hlt">variability</span> in long-range atmospheric transport to the Summit of the Greenland Ice Sheet</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Ice cores extracted from the Summit of the Greenland Ice Sheet date to >110 kyr b.p. and reveal fluctuations in chemical and physical characteristics on time scales ranging from days to millenia. Long-range atmospheric transport patterns contribute substantially to <span class="hlt">variability</span> in both airborne and snow-deposited chemical species, and are thus one of the most important considerations in assessing climate <span class="hlt">variability</span></p> <div class="credits"> <p class="dwt_author">Jonathan D. W. Kahl; Jennifer A. Galbraith; Dewayne A. Martinez</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">226</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015JGRD..120.1502X"> <span id="translatedtitle">Interannual to <span class="hlt">decadal</span> climate <span class="hlt">variability</span> of sea salt aerosols in the coupled climate model CESM1.0</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This study examines multiyear climate <span class="hlt">variability</span> associated with sea salt aerosols and their contribution to the <span class="hlt">variability</span> of shortwave cloud forcing (SWCF) using a 150 year simulation for preindustrial conditions of the Community Earth System Model version 1.0. The results suggest that changes in sea salt and related cloud and radiative properties on interannual timescales are dominated by the El Niño-Southern Oscillation cycle. Sea salt <span class="hlt">variability</span> on longer (interdecadal) timescales is associated with low-frequency <span class="hlt">variability</span> in the Pacific Ocean similar to the Interdecadal Pacific Oscillation but does not show a statistically significant spectral peak. A multivariate regression suggests that sea salt aerosol <span class="hlt">variability</span> may contribute to SWCF <span class="hlt">variability</span> in the tropical Pacific, explaining up to 20-30% of the variance in that region. Elsewhere, there is only a small sea salt aerosol influence on SWCF through modifying cloud droplet number and liquid water path that contributes to the change of cloud effective radius and cloud optical depth (and hence cloud albedo), producing a multiyear aerosol-cloud-wind interaction.</p> <div class="credits"> <p class="dwt_author">Xu, Li; Pierce, David W.; Russell, Lynn M.; Miller, Arthur J.; Somerville, Richard C. J.; Twohy, Cynthia H.; Ghan, Steven J.; Singh, Balwinder; Yoon, Jin-Ho; Rasch, Philip J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-02-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">227</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ClDy..tmp..223S"> <span id="translatedtitle">Inter-<span class="hlt">decadal</span> transition of the leading mode of inter-annual <span class="hlt">variability</span> of summer rainfall in East China and its associated atmospheric water vapor transport</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This study investigated the inter-<span class="hlt">decadal</span> variations of the leading empirical orthogonal function mode of the inter-annual <span class="hlt">variability</span> of summer precipitation in East China from 1951 to 2012. From the 1950s to the 1980s, the main rain belt in the positive-phase years was centered along the middle and lower Yangtze River Valleys, with negative rainfall anomalies in South China and North China. Since the 1990s, the main rain belt of the positive-phase years has been shifted northward. During the period 2001-2012, the center of the main rain belt in the positive-phase years has shifted to the regions between the Yangtze and Yellow Rivers. This shift could be attributed to the inter-<span class="hlt">decadal</span> variations of the anomalous atmospheric water vapor transport (AWVT) associated with the leading mode, which changed from a previously "anticyclone-cyclone" dipole structure to an anticyclonic monopole structure. The underlying physical mechanisms concerning the exertions from sea surface temperatures (SSTs) have also been preliminarily explored. The results indicate that the significant inter-<span class="hlt">decadal</span> transition in the leading mode of summer precipitation in East China and the causative anomalous AWVT from 2001 to 2012 may be related to an inter-<span class="hlt">decadal</span> change of inter-annual <span class="hlt">variability</span> of the tropical SSTs in both the Indian and Pacific Oceans, which has been below normal from 2001 to 2012. Therefore, the influence of the tropical SSTs on the inter-annual <span class="hlt">variability</span> of the East Asian climate may be diminished from 2001 to 2012, whereby a strongly coupled "anticyclone-cyclone" dipole-structured anomalous AWVT cannot be induced.</p> <div class="credits"> <p class="dwt_author">Sun, Bo; Wang, Huijun</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">228</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMPP33A2078J"> <span id="translatedtitle">Multi-<span class="hlt">decadal</span>-scale records of North Atlantic climate <span class="hlt">variability</span> during the last and present interglacials: Climate sensitivity and the AMOC</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">North Atlantic climate sensitivity plays a crucial role in understanding current and future developments of the Atlantic meridional overturning circulation (AMOC). A shifted configuration of Earth's orbital parameters about the Sun caused an approximate 3% higher radiative forcing during the Last Interglacial (LIG, MIS5e; 129-115kyr) and drove climate to measurably warmer conditions than during the Present Interglacial (PIG, Holocene, 11-0Kyr). Paleoceanographic time series of surface ocean climatology from Ocean Drilling Program (ODP) Site 976 in the Alboran Sea, westernmost Mediterranean, reflect the climatic <span class="hlt">variability</span> during the LIG and PIG. The site receives climate signals from the advection of Atlantic inflow waters confirming its quality to monitor North Atlantic climate <span class="hlt">variability</span>. Elevated rates of sedimentation deposition at the site enable resolving <span class="hlt">variability</span> at multi-<span class="hlt">decadal</span> resolution (60-90 yrs). Sea surface temperature (SST) time series were established from element concentrations (Mg/Ca) in the planktonic foraminifera Globigerina bulloides. SST from alkenones were also measured for comparison purposes. Planktonic oxygen isotopes from G. bulloides allow direct comparison with speleothems and ice cores. LIG SST are between 3°- 6°C warmer than PIG SST and multi-<span class="hlt">decadal</span>-scale <span class="hlt">variability</span> by 4°C and more is indicated by highly <span class="hlt">variable</span> Mg/Ca ratios. This <span class="hlt">variability</span> persisted during the LIG climatic optimum, confirming that SST and climatic <span class="hlt">variability</span> were independent of large ice sheets. The high <span class="hlt">variability</span> is contrasted by more stable SST in the Uk37-derived SST record, plausibly alluding to differential SST recording by the molecular biomarker proxy. Correlation with ?18O records from European speleothems suggests the SST pattern reflects climate of the western North Atlantic region. The LIG SST pattern at ODP 976 differs from that at open North Atlantic settings where maximum SST during the LIG climatic optimum remained some 6°C below that at ODP976 while converging with levels at ODP976 in the later stages of the LIG. The ODP976 SST record suggests more <span class="hlt">variable</span> climatic conditions and together with similar <span class="hlt">variability</span> seen in benthic ?13C records at Atlantic sites bears implications for AMOC stability and <span class="hlt">variability</span>. This is a contribution of the European Commission FP7 Collaborative Project "Past4Future".</p> <div class="credits"> <p class="dwt_author">Jimenez-Amat, P.; Zahn, R.; Martrat, B.; Grimalt, J. O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">229</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFMGC11D1028L"> <span id="translatedtitle">The Parana paradox: can a model explain the <span class="hlt">decadal</span> impacts of climate <span class="hlt">variability</span> and land-cover change?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Since the 1970s, despite a decrease in rainfall, flow in the Parana river has increased. This paradox is explored using the Ecosystem Demography (ED) model. If there were no change in land cover, the modeled runoff decreased from the 1970s to the 2000s by 11.8% (with 1970 land cover) or 18.8% (with 2008 land cover). When the model is run holding climate constant, the <span class="hlt">decadal</span> average of the modeled runoff increased by 24.4% (with the 1970s climate) or by 33.6% (with 2000s climate). When the model is run allowing both the actual climate and land-cover changes, the model gives an increase in the <span class="hlt">decadal</span> average of runoff by 8.5%. This agrees well with 10.5% increase in the actual stream flow as measured at Itaipu. There are three main conclusions from this work. First, the ED model is able to explain a major, paradoxical, reality in the Parana basin. Second, it is necessary to take into account both climate and land use changes when exploring past or future changes in river flows. Third, the ED model, now coupled with a regional climate model (i.e., EDBRAMS), is a sound basis for exploring likely changes in river flows in major South American rivers.</p> <div class="credits"> <p class="dwt_author">Lee, E.; Moorcroft, P. R.; Livino, A.; Briscoe, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">230</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020080613&hterms=shapes+colors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dshapes%2Bcolors"> <span id="translatedtitle">Subtropical Gyre <span class="hlt">Variability</span> <span class="hlt">Observed</span> by Ocean Color Satellites</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The subtropical gyres of the world are extensive, coherent regions that occupy about 40% of the surface of the earth. Once thought to be homogeneous and static habitats, there is increasing evidence that mid-latitude gyres exhibit substantial physical and biological <span class="hlt">variability</span> on a variety of time scales. While biological productivity within these oligotrophic regions may be relatively small, their immense size makes their total contribution significant. Global distributions of dynamic height derived from satellite altimeter data, and chlorophyll concentration derived from satellite ocean color data, show that the dynamic center of the gyres, the region of maximum dynamic height where the thermocline is deepest, does not coincide with the region of minimum chlorophyll concentration. The physical and biological processes by which this distribution of ocean properties is maintained, and the spatial and temporal scales of <span class="hlt">variability</span> associated with these processes, are analyzed using global surface chlorophyll-a concentrations, sea surface height, sea surface temperature and surface winds from operational satellite and meteorological sources, and hydrographic data from climatologies and individual surveys. Seasonal and interannual <span class="hlt">variability</span> in the areal extent of the subtropical gyres are examined using 8 months (November 1996 - June 1997) of OCTS and nearly 5 years (September 1997 - June 02) of SeaWiFS ocean color data and are interpreted in the context of climate <span class="hlt">variability</span> and measured changes in other ocean properties (i.e., wind forcing, surface currents, Ekman pumping, and vertical mixing). The North Pacific and North Atlantic gyres are <span class="hlt">observed</span> to be shrinking over this period, while the South Pacific, South Atlantic, and South Indian Ocean gyres appear to be expanding.</p> <div class="credits"> <p class="dwt_author">McClain, Charles R.; Signorini, Sergio R.; Christian, James R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">231</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20140013029&hterms=biofuel+energy+USA&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dbiofuel%2Benergy%2BUSA"> <span id="translatedtitle">Multi-<span class="hlt">Decadal</span> Aerosol Variations from 1980 to 2009: A Perspective from <span class="hlt">Observations</span> and a Global Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Aerosol variations and trends over different land and ocean regions during 1980-2009 are analyzed with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and <span class="hlt">observations</span> from multiple satellite sensors and ground-based networks. Excluding time periods with large volcanic influences, the tendency of aerosol optical depth (AOD) and surface concentration over polluted land regions is consistent with the anthropogenic emission changes.The largest reduction occurs over Europe, and regions in North America and Russia also exhibit reductions. On the other hand, East Asia and South Asia show AOD increases, although relatively large amount of natural aerosols in Asia makes the total changes less directly connected to the pollutant emission trends. Over major dust source regions, model analysis indicates that the dust emissions over the Sahara and Sahel respond mainly to the near-surface wind speed, but over Central Asia they are largely influenced by ground wetness. The decreasing dust trend in the tropical North Atlantic is most closely associated with the decrease of Sahel dust emission and increase of precipitation over the tropical North Atlantic, likely driven by the sea surface temperature increase. Despite significant regional trends, the model-calculated global annual average AOD shows little changes over land and ocean in the past three <span class="hlt">decades</span>, because opposite trends in different regions cancel each other in the global average. This highlights the need for regional-scale aerosol assessment, as the global average value conceals regional changes, and thus is not sufficient for assessing changes in aerosol loading.</p> <div class="credits"> <p class="dwt_author">Chin, Mian; Diehl, T.; Tan, Q.; Prospero, J. M.; Kahn, R. A.; Remer, L. A.; Yu, H.; Sayer, A. M.; Bian, H.; Geogdzhayev, I. V.; Holben, B. N.; Howell, S. G.; Huebert, B. J.; Hsu, N. C.; Kim, D.; Kucsera, T. L.; Levy, R. C.; Mishchenko, M. I.; Pan, X.; Quinn, P. K.; Schuster, G. L.; Streets, D. G.; Strode, S. A.; Torres, O.; Zhao, X.-P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">232</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015IzPSE..51..176M"> <span id="translatedtitle">The free oscillations of the earth excited by three strongest earthquakes of the past <span class="hlt">decade</span> according to deformation <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Based on the deformation data provided by the Baksan laser interferometer-strainmeter measurements, the free oscillations of the Earth (FOE) excited by the three strongest earthquakes of the past <span class="hlt">decade</span> are analyzed. These seismic events include the Great Sumatra-Andaman earthquake that occurred in 2004 in the Indian Ocean, the Mauli earthquake of 2010 in Chile, and the Great Tohoku earthquake of March 2011 in Japan. The frequency-time structure of the free oscillations is studied, and the pattern of interaction between the modes with close frequencies (cross-coupling effect) is explored. For each earthquake, the correspondence of the <span class="hlt">observed</span> FOE modes to the model predictions by the PREM model is investigated. A reliable consistent shift towards the high frequency of the toroidal modes with angular degree l = 12-19 is revealed. The maximal energy density of the toroidal oscillations is concentrated in the upper mantle of the Earth. Therefore, the established effect corresponds to the higher velocity of the shear waves in the upper mantle than it is predicted by the PREM model.</p> <div class="credits"> <p class="dwt_author">Milyukov, V. K.; Vinogradov, M. P.; Mironov, A. P.; Myasnikov, A. V.; Perelygin, N. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">233</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4394915"> <span id="translatedtitle">Clinical Research Quo Vadis? Trends in Reporting of Clinical Trials and <span class="hlt">Observational</span> Study Designs Over Two <span class="hlt">Decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Background Multiple classifications have been developed that classify the medical literature into different levels of evidence to facilitate the evaluation of study results and practice of evidence-based medicine. The suggested hierarchies of evidence are generally based on the type of study design; randomized, controlled clinical trials constitute the top level of evidence while case reports rank the lowest among epidemiologic study designs. However, little is known about the frequency with which different study designs appear in the medical literature overall. The purpose of this study was to describe trends in the frequency of reports of randomized control trials (RCTs) as compared to other study designs in the medical literature over two <span class="hlt">decades</span>. Methods Data about the prevalence of various types of study designs in the medical literature over the last two <span class="hlt">decades</span> (years 1990 - 2009) were abstracted from PubMed, validated and subjected to cross-sectional and longitudinal analysis. Results In the last 20 years, the annual rate of publication of journal articles has more than doubled. During this period, the percentage of <span class="hlt">observational</span> studies increased from 29.9% to 40.5%, the percentage of reports of RCTs increased minimally, and there was a striking decline in the percentage of case reports (from 49.8% to 33.6%) in the medical literature overall. In contrast, in three selected, highly cited medical journals, the percentage of reports of RCTs increased by almost 10%. Surprisingly, the percentage of articles classified as case reports also increased (from 36.3% to 43.8%) in these three journals, while the percentage of reports of cohort and case-control studies decreased. Conclusion Though the relative frequency of reports from RCTs has not changed substantially in the last 20 years, cohort studies and case-control studies have largely supplanted simple case reports. In contrast, in high impact journals, the representation of RCTs and case reports has increased, with corresponding declines in reports based on other study designs. Further research will be needed to determine whether those trends in publication have resulted in more robust evidence and faster advancement of medical knowledge.</p> <div class="credits"> <p class="dwt_author">Wyler von Ballmoos, Moritz C.; Ware, James H.; Haring, Bernhard</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">234</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20010023033&hterms=signs+spring&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsigns%2Bspring"> <span id="translatedtitle">Sea Ice <span class="hlt">Variability</span> in the Sea of Okhotsk from Passive Microwave Satellite <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The Sea of Okhotsk, located between 50 and 60 N, is bounded by the Kamchatka Peninsula, Siberia, Sakhalin Island, and the Kuril Island chain and is the largest midlatitude seasonal sea ice zone in the Northern Hemisphere. The winter sea ice cover begins to form in November and expands to cover most of the sea by March. Over the following three months, the ice retreats with only small ice-covered areas remaining by the beginning of June. The sea is ice free or nearly ice free on average for six months of the year, from June through November. The recent compilation of a consistent, long-term record of Northern Hemisphere sea ice extents based on passive microwave satellite <span class="hlt">observations</span> from the Nimbus 7 Scanning Multichannel Microwave Radiometer and from four Defense Meteorological Satellite Program Special Sensor Microwave Imagers provides the basis for assessing long-term sea ice extent <span class="hlt">variability</span> in the Sea of Okhotsk. Analysis of this 20-year data record (1979-1998) shows that based on yearly averages the overall extent of the Sea of Okhotsk ice cover is decreasing at the rate of -8.1+/-2.1x10(exp 3) sq km/yr (-17.2%/<span class="hlt">decade</span>), in contrast to the rate of decrease of -33.3+/-0.7x10(exp 3) sq km/yr (-2.7%/<span class="hlt">decade</span>) for the Northern Hemisphere as a whole. There is large regional sea ice extent <span class="hlt">variability</span> of the Arctic ice cover. Two of the nine Arctic regions analyzed, the Bering Sea and the Gulf of St. Lawrence, show increases of 0.8+/-1.4xl0(exp 3) sq km/yr (2.7%/<span class="hlt">decade</span>) and 1.2+/-0.5xl0(exp 3) sq km/yr (17.1%/<span class="hlt">decade</span>), respectively. Interestingly, the Sea of Okhotsk and the Gulf of St. Lawrence show about equal percentage changes, but of opposite sign. The Sea of Okhotsk exhibits its greatest percent decrease (-24.3%/<span class="hlt">decade</span>) during spring (April-June). The year of maximum winter sea ice extent for the Sea of Okhotsk was 1979, whereas the minimum winter sea ice extent occurred in 1984.</p> <div class="credits"> <p class="dwt_author">Cavalieri, Donald J.; Zukor, Dorothy (Technical Monitor)</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">235</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.7334C"> <span id="translatedtitle">Hydrological <span class="hlt">variability</span> from gauging stations and simulated SWOT data, for major French rivers over the past <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">This study was carried out in the framework of the program Surface Water and Ocean Topography (SWOT) associated to the National Center of Space Studies (CNES). Basing on discharge measurements, and simulated Surface Water and Ocean Topography (SWOT) data, we have investigated the hydrological <span class="hlt">variability</span> of the main French rivers (Seine, Loire, Garonne and Rhône) by the use of a minimum, maximum and mean annual discharge analyses, Loess and wavelet approach (continuous wavelet analyses and wavelet coherence analyses). Results show (i) strong coherence between the four watershed discharges, varying between 73% and 92% and (ii) three different periods for hydrological <span class="hlt">variability</span>: before 1970, between 1970 and 1990, and after 1990. From these results, simulated SWOT data and discharges are compared for these three periods using same analyses. Simulated SWOT data are obtained by re-sampling river discharges from the SWOT crossing time calculated. Simulated SWOT data can reproduce the hydrological <span class="hlt">variability</span> of rivers despite number of SWOT passages (from two to four). These results are validated by coherence wavelet, which underlines coherence higher than 90% between simulated SWOT data and in-situ discharge. However, the results indicate that simulated SWOT data don't reproduce exactly the minimum and maximum annual discharge: (i) maximum annual SWOT data are underestimated and (ii) minimum annual SWOT data are overestimated</p> <div class="credits"> <p class="dwt_author">Chevalier, Laetitia; Laignel, Benoit; Turki, Imen; Lyard, Florent; Lion, Christine</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">236</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20000070387&hterms=skin+surface+temperatures&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dskin%2Bsurface%2Btemperatures"> <span id="translatedtitle"><span class="hlt">Observations</span> of Land Surface <span class="hlt">Variability</span> Using Passive Microwave Sensing</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Understanding the global <span class="hlt">variability</span> of land surface wetness (soil moisture), skin temperature, and related surface fluxes of heat and moisture is key to assessing the importance of the land surface in influencing climate. The feasibility of producing model estimates of these quantities is being studied as part of the International Satellite Land Surface Climatology Project (ISLSCP) Global Soil Wetness Project (GSWP). In the GSWP approach, meteorological <span class="hlt">observations</span> and analyses are used to drive global circulation models. Satellite measurements can provide independent estimates of key land surface parameters that are needed for initializing and validating the climate models and for monitoring long-term change. Satellite <span class="hlt">observations</span> of the land surface can also be assimilated into soil models to estimate moisture in the root zone. In our research, passive microwave satellite data recorded during 1978-1987 from the Nimbus-7 Scanning Multichannel Microwave Radiometer (SMMR) are being used to examine spatial and temporal trends in surface soil moisture, vegetation, and temperature. These data include <span class="hlt">observations</span> at C and X bands (6.6 and 10.7 GHz), which are not available on the current Special Sensor Microwave/Imager (SSM/I) and are precursors to data that will become available from the Advanced Microwave Scanning Radiometer (AMSR) on Advanced Earth <span class="hlt">Observing</span> Satellite (ADEOS-II) and Earth <span class="hlt">Observing</span> System (EOS) PM1 in the year 2000. A chart shows a time-series of SMMR-derived surface temperature, T-e and surface soil moisture M, retrieved on a 0.5 deg x 0.5 deg grid and further averaged over a 4 deg x 10 deg study region in the African Sahel. Also shown are National Center for Environmental Prediction (NCEP) model outputs of surface temperature, T-sfc, and soil wetness, Soil-w. The <span class="hlt">variables</span> have been scaled to have similar dynamic ranges on the plots. The NCEP data from the NCEP Reanalysis Project are monthly averages on a 2.5 deg x 2.5 deg grid averaged over the 4 deg x 10 deg study area. Comparisons of SMMR retrievals with forecast model output show the potential of the satellite data for validating model output and monitoring long-term trends. Continuing work will extend these results to other regions to validate the retrievals more quantitatively. In preparation for the launch of AMSR, field experiments are planned in collaboration with the Global Energy and Water Cycle Experiment (GEWEX) Coordinated Enhanced <span class="hlt">Observing</span> Period (CEOP) experiments to evaluate the satellite-derived soil moisture measurements and to demonstrate their usefulness for land surface hydrology and climate. Additional information is contained in the original.</p> <div class="credits"> <p class="dwt_author">Njoku, Eni G.</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">237</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22127076"> <span id="translatedtitle"><span class="hlt">OBSERVATIONS</span> OF THERMAL FLARE PLASMA WITH THE EUV <span class="hlt">VARIABILITY</span> EXPERIMENT</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">One of the defining characteristics of a solar flare is the impulsive formation of very high temperature plasma. The properties of the thermal emission are not well understood, however, and the analysis of solar flare <span class="hlt">observations</span> is often predicated on the assumption that the flare plasma is isothermal. The EUV <span class="hlt">Variability</span> Experiment (EVE) on the Solar Dynamics Observatory provides spectrally resolved <span class="hlt">observations</span> of emission lines that span a wide range of temperatures (e.g., Fe XV-Fe XXIV) and allow for thermal flare plasma to be studied in detail. In this paper we describe a method for computing the differential emission measure distribution in a flare using EVE <span class="hlt">observations</span> and apply it to several representative events. We find that in all phases of the flare the differential emission measure distribution is broad. Comparisons of EVE spectra with calculations based on parameters derived from the Geostationary Operational Environmental Satellites soft X-ray fluxes indicate that the isothermal approximation is generally a poor representation of the thermal structure of a flare.</p> <div class="credits"> <p class="dwt_author">Warren, Harry P.; Doschek, George A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Mariska, John T. [School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Drive, Fairfax, VA 22030 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-06-20</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">238</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AN....331..843D"> <span id="translatedtitle">Error analysis of proper motions in declination obtained for 807 Hipparcos stars from PZT <span class="hlt">observations</span> over many <span class="hlt">decades</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">After publication of the Hipparcos catalogue (in 1997), a few new astrometric catalogues have appeared (TYCHO-2, ARIHIP, etc.), as a good combination of the Hipparcos satellite and ground-based data, to get more accurate coordinates and proper motions of stars than the Hipparcos catalogue ones. There are also investigations on improving the Hipparcos coordinates and proper motions by using the astrometric <span class="hlt">observations</span> of latitude and universal time variations (via <span class="hlt">observed</span> stars referred to Hipparcos catalogue), together with Hipparcos data, carried out during the last few years. These kind of ground-based data were collected at the end of the last century by J. Vondrák. %(at Astronomical Institute, Academy There are about 4.4 million optical <span class="hlt">observations</span> made worldwide at 33 observatories and with 47 instruments during 1899.7-1992.0; our Belgrade visual zenith telescope data (for the period 1949.0-1986.0) were included. First of all, these data were used to determine the Earth Orientation Parameters - EOP, but they are also useful for the opposite task - to check the accuracy of coordinates and proper motions of Hipparcos stars which were <span class="hlt">observed</span> from the ground over many <span class="hlt">decades</span>. Here, we use the latitude part of ten Photographic Zenith Tubes - PZT data (more than 0.9 million <span class="hlt">observations</span> made at 6 observatories during the time interval 1915.8-1992.0), and combine them with the Hipparcos catalogue ones, with suitable weights, in order to check the proper motions in declination for 807 common PZT/Hipparcos stars (and to construct the PZT catalogue of ?? for 807 stars). Our standard errors in proper motions in declination of these stars are less than or equal to the Hipparcos ones for 423 stars. The mean value of standard errors of 313 stars <span class="hlt">observed</span> over more than 20 years by PZT is 0.40 mas/yr. This is 53% of 0.75 mas/yr (the suitable value from the Hipparcos catalogue). We used the Least Squares Method - LSM with the linear model. Our results are in good agreement with the Earth Orientation Catalogue - EOC-2 and the new Hipparcos ones. The main steps of the method and the investigations of systematic errors in determined proper motions (the proper motion differences with respect to the Hipparcos values, the EOC-2 ones and the new Hipparcos ones, as a function of ?, ?, and magnitude) are presented here. A comparison of the four catalogues by pairs shows that there is no significant relationship between the differences of their ?? values and magnitudes and color indices of the common 807 stars. All catalogues have relatively small random and systematic errors which are close to each other. However, the comparison shows that our formal errors are too small. They are underestimated by a factor of nearly 1.7 (for EOC-2, it is 2.0) if we take the new Hipparcos (or Hipparcos) data as reference. Data from STELLA</p> <div class="credits"> <p class="dwt_author">Damljanovi?, G.; Pejovi?, N.; Pejovi?, N.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">239</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2001AAS...199.9001H"> <span id="translatedtitle">Monitoring ? Scuti <span class="hlt">Variables</span> with Coordinated <span class="hlt">Observing</span> of Small Telescopes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Beginning with a Research Experience for Teachers (RET) program this past summer a research effort has been started that will allow undergraduates to collaborate with high school students in monitoring a number of bright <span class="hlt">variable</span> stars of the ? Scuti variety. This program will make use of the Brigham Young University 16" David Derrick Telescope and 8" Ferdinand Feghoot Telescope along with a new 10" Meade LX-200 installed at Payson High School. The initial targets for this program include DQ Cephei, DX Ceti, V474 Monocerotis, V376 Persei, ? Scuti, and V966 Herculis. Spectroscopic follow-up <span class="hlt">observations</span> will be made at the 1.2-m Telescope of the Dominion Astrophysical Observatory in Victoria, B.C., Canada. We hope this program will lay the ground work for additional small telescopes at high schools throughout Utah. Preliminary results will be presented. Research Partially supported by NSF REU Program PHY-9988852</p> <div class="credits"> <p class="dwt_author">Hintz, E.; Jeffery, E.; Walter, L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">240</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JHyd..517..458N"> <span id="translatedtitle">On the use of Standardized Drought Indices under <span class="hlt">decadal</span> climate <span class="hlt">variability</span>: Critical assessment and drought policy implications</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Since the recent High Level Meeting on National Drought Policy held in Geneva in 2013, a greater concern about the creation and adaptation of national drought monitoring systems is expected. Consequently, backed by international recommendations, the use of Standardized Drought Indices (SDI), such as the Standardized Precipitation Index (SPI), as an operational basis of drought monitoring systems has been increasing in many parts of the world. Recommendations for the use of the SPI, and consequently, those indices that share its properties, do not take into account the limitations that this type of index can exhibit under the influence of multidecadal climate <span class="hlt">variability</span>. These limitations are fundamentally related to the lack of consistency among the operational definition expressed by this type of index, the conceptual definition with which it is associated and the political definition it supports. Furthermore, the limitations found are not overcome by the recommendations for their application. This conclusion is supported by the long-term study of the Standardized Streamflow Index (SSI) in the arid north-central region of Chile, under the influence of multidecadal climate <span class="hlt">variability</span>. The implications of the findings of the study are discussed with regard to their link to aspects of drought policy in the cases of Australia, the United States and Chile.</p> <div class="credits"> <p class="dwt_author">Núñez, J.; Rivera, D.; Oyarzún, R.; Arumí, J. L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-09-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_11");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' 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onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">241</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20080023356&hterms=soil+moisture&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsoil%2Bmoisture"> <span id="translatedtitle">Field <span class="hlt">Observations</span> of Soil Moisture <span class="hlt">Variability</span> across Scales</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">In this study, over 36,000 ground-based soil moisture measurements collected during the SGP97, SGP99, SMEX02, and SMEX03 field campaigns were analyzed to characterize the behavior of soil moisture <span class="hlt">variability</span> across scales. The field campaigns were conducted in Oklahoma and Iowa in the central USA. The Oklahoma study region is sub-humid with moderately rolling topography, while the Iowa study region is humid with low-relief topography. The relationship of soil moisture standard deviation, skewness and the coefficient of variation versus mean moisture content was explored at six distinct extent scales, ranging from 2.5 m to 50 km. Results showed that <span class="hlt">variability</span> generally increases with extent scale. The standard deviation increased from 0.036 cm3/cm3 at the 2.5-m scale to 0.071 cm3/cm3 at the 50-km scale. The log standard deviation of soil moisture increased linearly with the log extent scale, from 16 m to 1.6 km, indicative of fractal scaling. The soil moisture standard deviation versus mean moisture content exhibited a convex upward relationship at the 800-m and 50-km scales, with maximum values at mean moisture contents of roughly 0.17 cm3/cm3 and 0.19 cm3/cm3, respectively. An empirical model derived from the <span class="hlt">observed</span> behavior of soil moisture <span class="hlt">variability</span> was used to estimate uncertainty in the mean moisture content for a fixed number of samples at the 800-m and 50-km scales, as well as the number of ground-truth samples needed to achieve 0.05 cm3/cm3 and 0.03 cm3/cm3 accuracies. The empirical relationships can also be used to parameterize surface soil moisture variations in land surface and hydrological models across a range of scales. To our knowledge, this is the first study to document the behavior of soil moisture <span class="hlt">variability</span> over this range of extent scales using ground-based measurements. Our results will contribute not only to efficient and reliable satellite validation, but also to better utilization of remotely sensed soil moisture products for enhanced modeling and prediction.</p> <div class="credits"> <p class="dwt_author">Famiglietti, James S.; Ryu, Dongryeol; Berg, Aaron A.; Rodell, Matthew; Jackson, Thomas J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">242</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://escholarship.org/uc/item/7535715n?query=rainfall+AND+models"> <span id="translatedtitle">North American Climate in CMIP5 Experiments. Part II: Evaluation of Historical Simulations of Intraseasonal to <span class="hlt">Decadal</span> <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">the CEOF1 rainfall pattern for each model simulation versusof rainfall and 850-hPa winds from 18 CMIP5 models. Figure 1rainfall anomalies associated with the CEOF1 based on both <span class="hlt">observations</span> and model</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">243</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20040111406&hterms=Russia+America&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2528Russia%2BAmerica%2529"> <span id="translatedtitle">Interannual and Seasonal <span class="hlt">Variability</span> of Biomass Burning Emissions Constrained by Satellite <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We present a methodology for estimating the seasonal and interannual variation of biomass burning designed for use in global chemical transport models. The average seasonal variation is estimated from 4 years of fire-count data from the Along Track Scanning Radiometer (ATSR) and 1-2 years of similar data from the Advanced Very High Resolution Radiometer (AVHRR) World Fire Atlases. We use the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) data product as a surrogate to estimate interannual <span class="hlt">variability</span> in biomass burning for six regions: Southeast Asia, Indonesia and Malaysia, Brazil, Central America and Mexico, Canada and Alaska, and Asiatic Russia. The AI data set is available from 1979 to the present with an interruption in satellite <span class="hlt">observations</span> from mid-1993 to mid-1996; this data gap is filled where possible with estimates of area burned from the literature for different regions. Between August 1996 and July 2000, the ATSR fire-counts are used to provide specific locations of emissions and a record of interannual <span class="hlt">variability</span> throughout the world. We use our methodology to estimate mean seasonal and interannual variations for emissions of carbon monoxide from biomass burning, and we find that no trend is apparent in these emissions over the last two <span class="hlt">decades</span>, but that there is significant interannual <span class="hlt">variability</span>.</p> <div class="credits"> <p class="dwt_author">Duncan, Bryan N.; Martin, Randall V.; Staudt, Amanda C.; Yevich, Rosemarie; Logan, Jennifer A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2003-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">244</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013OcDyn..63..347S"> <span id="translatedtitle">Evaluation of a Finite-Element Sea-Ice Ocean Model (FESOM) set-up to study the interannual to <span class="hlt">decadal</span> <span class="hlt">variability</span> in the deep-water formation rates</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The characteristics of a global set-up of the Finite-Element Sea-Ice Ocean Model under forcing of the period 1958-2004 are presented. The model set-up is designed to study the <span class="hlt">variability</span> in the deep-water mass formation areas and was therefore regionally better resolved in the deep-water formation areas in the Labrador Sea, Greenland Sea, Weddell Sea and Ross Sea. The sea-ice model reproduces realistic sea-ice distributions and <span class="hlt">variabilities</span> in the sea-ice extent of both hemispheres as well as sea-ice transport that compares well with <span class="hlt">observational</span> data. Based on a comparison between model and ocean weather ship data in the North Atlantic, we <span class="hlt">observe</span> that the vertical structure is well captured in areas with a high resolution. In our model set-up, we are able to simulate <span class="hlt">decadal</span> ocean <span class="hlt">variability</span> including several salinity anomaly events and corresponding fingerprint in the vertical hydrography. The ocean state of the model set-up features pronounced <span class="hlt">variability</span> in the Atlantic Meridional Overturning Circulation as well as the associated mixed layer depth pattern in the North Atlantic deep-water formation areas.</p> <div class="credits"> <p class="dwt_author">Scholz, Patrick; Lohmann, Gerrit; Wang, Qiang; Danilov, Sergey</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">245</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26952993"> <span id="translatedtitle">Canonical form <span class="hlt">observer</span> design for non-linear time-<span class="hlt">variable</span> systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">An <span class="hlt">observer</span> of canonical (phase-<span class="hlt">variable</span>) form for non-linear time-<span class="hlt">variable</span> systems is introduced. The development of this non-linear time-<span class="hlt">variable</span> form requires regularity of the non-linear time-<span class="hlt">variable</span>- <span class="hlt">observability</span> matrix of the system. From the relationships derived during the development, it follows that a non-linear time-<span class="hlt">variable</span> <span class="hlt">observer</span> can be dimensioned by an eigenvalue assignment with respect to the canonical state coordinates if a</p> <div class="credits"> <p class="dwt_author">D. BESTLE; M. ZEITZ</p> <p class="dwt_publisher"></p> <p class="publishDate">1983-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">246</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=latent&pg=7&id=EJ812277"> <span id="translatedtitle"><span class="hlt">Observed</span> <span class="hlt">Variables</span> Are Indeed More Mysterious than Commonly Supposed</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">The author comments on an article about psychometrics titled "Latent <span class="hlt">Variable</span> Theory" by Denny Borsboom and printed elsewhere in this issue. The author states that Borsboom's conclusion that all <span class="hlt">variables</span> should be considered latent until proven otherwise is sound, and that his basis for conclusion rests on the relation between the <span class="hlt">variable</span>…</p> <div class="credits"> <p class="dwt_author">Howell, Roy D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">247</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ACP....14.3657C"> <span id="translatedtitle">Multi-<span class="hlt">decadal</span> aerosol variations from 1980 to 2009: a perspective from <span class="hlt">observations</span> and a global model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Aerosol variations and trends over different land and ocean regions from 1980 to 2009 are analyzed with the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model and <span class="hlt">observations</span> from multiple satellite sensors and available ground-based networks. Excluding time periods with large volcanic influence, aerosol optical depth (AOD) and surface concentration over polluted land regions generally vary with anthropogenic emissions, but the magnitude of this association can be dampened by the presence of natural aerosols, especially dust. Over the 30-year period in this study, the largest reduction in aerosol levels occurs over Europe, where AOD has decreased by 40-60% on average and surface sulfate concentrations have declined by a factor of up to 3-4. In contrast, East Asia and South Asia show AOD increases, but the relatively high level of dust aerosols in Asia reduces the correlation between AOD and pollutant emission trends. Over major dust source regions, model analysis indicates that the change of dust emissions over the Sahara and Sahel has been predominantly driven by the change of near-surface wind speed, but over Central Asia it has been largely influenced by the change of the surface wetness. The decreasing dust trend in the North African dust outflow region of the tropical North Atlantic and the receptor sites of Barbados and Miami is closely associated with an increase of the sea surface temperature in the North Atlantic. This temperature increase may drive the decrease of the wind velocity over North Africa, which reduces the dust emission, and the increase of precipitation over the tropical North Atlantic, which enhances dust removal during transport. Despite significant trends over some major continental source regions, the model-calculated global annual average AOD shows little change over land and ocean in the past three <span class="hlt">decades</span>, because opposite trends in different land regions cancel each other out in the global average, and changes over large open oceans are negligible. This highlights the necessity for regional-scale assessment of aerosols and their climate impacts, as global-scale average values can obscure important regional changes.</p> <div class="credits"> <p class="dwt_author">Chin, M.; Diehl, T.; Tan, Q.; Prospero, J. M.; Kahn, R. A.; Remer, L. A.; Yu, H.; Sayer, A. M.; Bian, H.; Geogdzhayev, I. V.; Holben, B. N.; Howell, S. G.; Huebert, B. J.; Hsu, N. C.; Kim, D.; Kucsera, T. L.; Levy, R. C.; Mishchenko, M. I.; Pan, X.; Quinn, P. K.; Schuster, G. L.; Streets, D. G.; Strode, S. A.; Torres, O.; Zhao, X.-P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">248</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/45423463"> <span id="translatedtitle">Three <span class="hlt">decades</span> of <span class="hlt">observed</span> soil acidification in the Calhoun Experimental Forest: Has acid rain made a difference?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Three <span class="hlt">decades</span> of repeated soil sampling from eight permanent plots at the Calhoun Experimental Forest in South Carolina allowed the authors to estimate the rate of soil acidification, the chemical changes in the soil exchange complex, and the natural and anthropogenic sources of acidity contribution to these processes. During the first 34 yr of loblolly pine (Pinus taeda L.) forest</p> <div class="credits"> <p class="dwt_author">Daniel Markewitz; Daniel D. Richter; H. Lee Allen; J. Byron Urrego</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">249</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ERL.....9b5004F"> <span id="translatedtitle">Regional and landscape-scale <span class="hlt">variability</span> of Landsat-<span class="hlt">observed</span> vegetation dynamics in northwest Siberian tundra</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Widespread increases in Arctic tundra productivity have been documented for <span class="hlt">decades</span> using coarse-scale satellite <span class="hlt">observations</span>, but finer-scale <span class="hlt">observations</span> indicate that changes have been very uneven, with a high degree of landscape- and regional-scale heterogeneity. Here we analyze time-series of the Normalized Difference Vegetation Index (NDVI) <span class="hlt">observed</span> by Landsat (1984-2012), to assess landscape- and regional-scale <span class="hlt">variability</span> of tundra vegetation dynamics in the northwest Siberian Low Arctic, a little-studied region with varied soils, landscape histories, and permafrost attributes. We also estimate spatio-temporal rates of land-cover change associated with expansion of tall alder (Alnus) shrublands, by integrating Landsat time-series with very-high-resolution imagery dating to the mid-1960s. We compiled Landsat time-series for eleven widely-distributed landscapes, and performed linear regression of NDVI values on a per-pixel basis. We found positive net NDVI trends (‘greening’) in nine of eleven landscapes. Net greening occurred in alder shrublands in all landscapes, and strong greening tended to correspond to shrublands that developed since the 1960s. Much of the spatial <span class="hlt">variability</span> of greening within landscapes was linked to landscape physiography and permafrost attributes, while between-landscape <span class="hlt">variability</span> largely corresponded to differences in surficial geology. We conclude that continued increases in tundra productivity in the region are likely in upland tundra landscapes with fine-textured, cryoturbated soils; these areas currently tend to support discontinuous vegetation cover, but are highly susceptible to rapid increases in vegetation cover, as well as land-cover changes associated with the development of tall shrublands.</p> <div class="credits"> <p class="dwt_author">Frost, Gerald V.; Epstein, Howard E.; Walker, Donald A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">250</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020045387&hterms=Sea+surface+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%253A%2522Sea%2Bsurface%2Btemperature%2522"> <span id="translatedtitle">Seasonal to <span class="hlt">Decadal</span>-Scale <span class="hlt">Variability</span> in Satellite Ocean Color and Sea Surface Temperature for the California Current System</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Support for this project was used to develop satellite ocean color and temperature indices (SOCTI) for the California Current System (CCS) using the historic record of CZCS West Coast Time Series (WCTS), OCTS, WiFS and AVHRR SST. The ocean color satellite data have been evaluated in relation to CalCOFI data sets for chlorophyll (CZCS) and ocean spectral reflectance and chlorophyll OCTS and SeaWiFS. New algorithms for the three missions have been implemented based on in-water algorithm data sets, or in the case of CZCS, by comparing retrieved pigments with ship-based <span class="hlt">observations</span>. New algorithms for absorption coefficients, diffuse attenuation coefficients and primary production have also been evaluated. Satellite retrievals are being evaluated based on our large data set of pigments and optics from CalCOFI.</p> <div class="credits"> <p class="dwt_author">Mitchell, B. Greg; Kahru, Mati; Marra, John (Technical Monitor)</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">251</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014AJ....148...63S"> <span id="translatedtitle">Follow up <span class="hlt">Observations</span> of SDSS and CRTS Candidate Cataclysmic <span class="hlt">Variables</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present photometry and spectroscopy of 11 and 35 potential cataclysmic <span class="hlt">variables</span>, respectively, from the Sloan Digital Sky Survey, the Catalina Real-Time Transient Survey, and vsnet alerts. The photometry results include quasi-periodic oscillations during the decline of V1363 Cyg, nightly accretion changes in the likely Polar (AM Herculis binary) SDSS J1344+20, eclipses in SDSS J2141+05 with an orbital period of 76 ± 2 minutes, and possible eclipses in SDSS J2158+09 at an orbital period near 100 minutes. Time-resolved spectra reveal short orbital periods near 80 minutes for SDSS J0206+20, 85 minutes for SDSS J1502+33, and near 100 minutes for CSS J0015+26, RXS J0150+37, SDSS J1132+62, SDSS J2154+15, and SDSS J2158+09. The prominent He II line and velocity amplitude of SDSS J2154+15 are consistent with a Polar nature for this object, while the absence of this line and a low velocity amplitude argue against this classification for RXS J0150+37. Single spectra of 10 objects were obtained near outburst and the rest near quiescence, confirming the dwarf novae nature of these objects. Based on <span class="hlt">observations</span> obtained with the Apache Point Observatory (APO) 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium.</p> <div class="credits"> <p class="dwt_author">Szkody, Paula; Everett, Mark E.; Howell, Steve B.; Landolt, Arlo U.; Bond, Howard E.; Silva, David R.; Vasquez-Soltero, Stephanie</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">252</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2011AAS...21712605H"> <span id="translatedtitle">K-band <span class="hlt">Observations</span> of Sub-Gap Cataclysmic <span class="hlt">Variables</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present K-band spectroscopy of short period, ``sub-gap'' cataclysmic <span class="hlt">variable</span> (CV) systems obtained using ISAAC on the VLT. We show the infrared spectra (IR) for nine systems below the 2-3 hour period gap: V2051 Oph, V436 Cen, EX Hya, VW Hyi, Z Cha, WX Hyi, V893 Sco, RZ Leo, and TY PsA. We are able to clearly detect the secondary star in all but WX Hyi, V893 Sco, and TY PsA. We present the first direct detection of the secondary stars of V2051 Oph, 436 Cen, and determine new spectral classifications for EX Hya, VW Hyi, Z Cha, and RZ Leo. We find that the CO band strengths of all but Z Cha appear normal for their spectral types, in contrast to their longer period cousins above the period gap. This brings the total number of CVs with moderate resolution (R ? 2000) IR spectroscopy to forty-eight systems: six pre-CVs, thirty-one non-magnetic systems, and eleven magnetic or partially magnetic systems. We discuss the trends seen in the IR abundance patterns thus far, and highlight a potential link between anomalous abundances seen in the IR with the C IV/N V anomaly seen in the ultraviolet. We present a compilation of all systems with sufficient resolution IR <span class="hlt">observations</span> to assess the CO band strengths, and, by proxy, obtain an estimate on the C abundance on the secondary star.</p> <div class="credits"> <p class="dwt_author">Hamilton, Ryan T.; Harrison, T. E.; Tappert, C.; Howell, S. B.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">253</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/2140860"> <span id="translatedtitle"><span class="hlt">Observed</span> and simulated multidecadal <span class="hlt">variability</span> in the Northern Hemisphere</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Analyses of proxy based reconstructions of surface temperatures during the past 330 years show the existence of a distinct\\u000a oscillatory mode of <span class="hlt">variability</span> with an approximate time scale of 70 years. This <span class="hlt">variability</span> is also seen in instrumental\\u000a records, although the oscillatory nature of the <span class="hlt">variability</span> is difficult to assess due to the short length of the instrumental\\u000a record. The</p> <div class="credits"> <p class="dwt_author">T. L. Delworth; M. E. Mann</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">254</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015ClDy...44..359G"> <span id="translatedtitle"><span class="hlt">Observed</span> and SST-forced multidecadal <span class="hlt">variability</span> in global land surface air temperature</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The characteristics of multidecadal <span class="hlt">variability</span> (MDV) in global land surface air temperature (SAT) are analyzed based on <span class="hlt">observations</span>. The role of sea surface temperature (SST) variations in generating MDV in land SAT is assessed using atmospheric general circulation model simulations forced by <span class="hlt">observed</span> SST. MDV in land SAT exhibits regional differences, with amplitude larger than 0.3 °C mainly over North America, East Asia, Northern Eurasia, Northern Africa and Greenland for the study period of 1902-2004. MDV can account for more than 30 % of long-term temperature variation during the last century in most regions, especially more than 50 % in parts of the above-mentioned regions. The SST-forced simulations reproduce the <span class="hlt">observed</span> feature of zonal mean MDV in land SAT, though with weaker amplitude especially at the northern high-latitudes. Two types of MDV in land SAT, one of 60-year-timescale, mainly <span class="hlt">observed</span> in the northern mid-high-latitude lands, and another of 20-30-year-timescale, mainly <span class="hlt">observed</span> in the low-latitude lands, are also well reproduced. The SST-forced MDV accounts for more than 40 % amplitude of <span class="hlt">observed</span> MDV in most regions. Except for some sporadically distributed regions in central Eurasia, South America and Western Australia, the SST-forced multidecadal variations are well in-phase with <span class="hlt">observations</span>. The Atlantic Multidecadal Oscillation and Pacific <span class="hlt">Decadal</span> Oscillation signals are found dominant in MDV of both the <span class="hlt">observed</span> and SST-forced land SAT, suggesting important roles of these oceanic oscillations in generating MDV in global land SAT.</p> <div class="credits"> <p class="dwt_author">Gao, L. H.; Yan, Z. W.; Quan, X. W.</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">255</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/290164"> <span id="translatedtitle">Three <span class="hlt">decades</span> of <span class="hlt">observed</span> soil acidification in the Calhoun Experimental Forest: Has acid rain made a difference?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Three <span class="hlt">decades</span> of repeated soil sampling from eight permanent plots at the Calhoun Experimental Forest in South Carolina allowed the authors to estimate the rate of soil acidification, the chemical changes in the soil exchange complex, and the natural and anthropogenic sources of acidity contribution to these processes. During the first 34 yr of loblolly pine (Pinus taeda L.) forest growth, soil pH, decreased by 1 unit in the upper 0- to 15-cm of soils and by 0.4 and 0.3 units in the 15- to 35- and 35- to 60-cm layers, respectively. Throughout the 0- to 60-cm horizon, base cation depletion averaged 1.57 kmol{sub c} ha{sup {minus}1} yr{sup {minus}1} and effective and total acidity increased by 1.26 and 3.28 kmol{sub c} ha{sup {minus}1} yr{sup {minus}1}, respectively. A forest H{sup +} budget estimated for these <span class="hlt">decades</span> indicated that 38% of soil acidification was due to acid deposition, while 62% of soil acidification was due to acid disposition, while 62% of soil acidification was attributed to the internal functioning of the ecosystem. Soil samples archived during the three-<span class="hlt">decade</span> experiment also document decreases in soil-adsorbed SO{sub 4}{sup 2{minus}}, presumably in response to decreasing atmospheric inputs in recent years.</p> <div class="credits"> <p class="dwt_author">Markewitz, D.; Richter, D.D. [Duke Univ., Durham, NC (United States). Nicholas School of the Environment; Allen, H.L. [North Carolina State Univ., Raleigh, NC (United States); Urrego, J.B. [Smurfit-Carton de Colombia, Calli (Colombia). Investigacion Forestal</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">256</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.4290F"> <span id="translatedtitle">Non-stationary relationships between <span class="hlt">decadal</span> water storage changes over Australia and climate <span class="hlt">variability</span> of the El Niño Southern Oscillation and Indian Ocean Dipole</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Large-scale ocean-atmosphere interactions are hypothesized as the main drivers of water variations over the Australian continent. This study examines the relative contributions of the large-scale ocean-atmospheric processes in different time-scale variations of terrestrial water storage (TWS) over Australia. The aim is to determine whether the role of main climatic phenomena such as the El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) on water resources as appears to be a stationary relationship. The main analyses were performed on three <span class="hlt">decades</span> (1982-2012) of: (i) TWS changes over Australia from the World Wide Water Resources Assessment (W3RA) hydrological model, and (ii) statistically reconstructed TWS changes from the Gravity Recovery And Climate Experiment (GRACE) products. Reconstructions were derived by applying low-degree autoregressive models to relate basin averaged TWS changes, over the nine major river drainage basins of Australia, to input values of precipitation minus evaporation as well as the ENSO and IOD indices. Our results indicate that both intra-annual and seasonal simulation and forecast of TWS water storage changes associated with ENSO cycles have increased during the last two <span class="hlt">decades</span> of 1990 to 2010. The contribution of IOD to seasonal simulation and forecasts of TWS appears to have increased over the last <span class="hlt">decade</span>. The long-term influence of IOD in TWS changes, however, appears to have decreased slightly. Our results demonstrate non-stationary behaviour of TWS in terms of <span class="hlt">variability</span> and predictability due to the ENSO and IOD phenomena. Keywords: Australia; ENSO and IOD in Water Storage; Reconstruction; Non-stationary Impact</p> <div class="credits"> <p class="dwt_author">Forootan, Ehsan; Kusche, Jürgen; van Dijk, Albert; Awange, Joseph; Schumacher, Maike; Longuevergne, Laurent</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">257</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/1134073"> <span id="translatedtitle">Final Report for UW-Madison Portion of DE-SC0005301, "Collaborative Project: Pacific <span class="hlt">Decadal</span> <span class="hlt">Variability</span> and Central Pacific Warming El Niño in a Changing Climate"</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">This project funded two efforts at understanding the interactions between Central Pacific ENSO events, the mid-latitude atmosphere, and <span class="hlt">decadal</span> <span class="hlt">variability</span> in the Pacific. The first was an investigation of conditions that lead to Central Pacific (CP) and East Pacific (EP) ENSO events through the use of linear inverse modeling with defined norms. The second effort was a modeling study that combined output from the National Center for Atmospheric Research (NCAR) Community Atmospheric Model (CAM4) with the Battisti (1988) intermediate coupled model. The intent of the second activity was to investigate the relationship between the atmospheric North Pacific Oscillation (NPO), the Pacific Meridional Mode (PMM), and ENSO. These two activities are described herein.</p> <div class="credits"> <p class="dwt_author">Vimont, Daniel [University of Wisconsin - Madison</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-13</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">258</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/534525"> <span id="translatedtitle">Coupled ocean-atmosphere model system for studies of interannual-to-<span class="hlt">decadal</span> climate <span class="hlt">variability</span> over the North Pacific Basin and precipitation over the Southwestern United States</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">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-<span class="hlt">decadal</span> climate <span class="hlt">variability</span> 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.</p> <div class="credits"> <p class="dwt_author">Lai, Chung-Chieng A.</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">259</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/26950438"> <span id="translatedtitle">On <span class="hlt">observers</span> in multi-<span class="hlt">variable</span> control systems</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Many feedback control system designs require the availability of the state of the controlled plant. Since the plant state <span class="hlt">variables</span> are not generally available for direct measurement in practice a means for estimating these <span class="hlt">variables</span> is required. Attention is restricted to plants which are linear, time-invariant, finite-dimensional, dynamic systems in this paper. In this case, necessary and sufficient conditions are</p> <div class="credits"> <p class="dwt_author">J. J. BONGIORNO JR; D. C. YOULA</p> <p class="dwt_publisher"></p> <p class="publishDate">1968-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">260</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015ThApC.119..181Z"> <span id="translatedtitle">Six-<span class="hlt">decade</span> temporal change and seasonal decomposition of climate <span class="hlt">variables</span> in Lake Dianchi watershed (China): stable trend or abrupt shift?</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Meteorological trend analysis is a useful tool for understanding climate change and can provide useful information on the possibility of future change. Lake Dianchi is the sixth largest freshwater body in China with serious eutrophication. Algal blooms outbreak was proven to be closely associated with some climatic factors in Lake Dianchi. It is therefore essential to explore the trends of climatic time series to understand the mechanism of climate change on lake eutrophication. We proposed an integrated method of Mann-Kendall (MK) test, seasonal-trend decomposition using locally weighted regression (LOESS) (STL), and regime shift index (RSI) to decompose the trend analysis and identify the stable and abrupt changes of some climate <span class="hlt">variables</span> from 1951 to 2009. The <span class="hlt">variables</span> include mean air temperature (Tm), maximum air temperatures (Tmax), minimum air temperatures (Tmin), precipitation (Prec), average relative humidity (Hum), and average wind speed (Wind). The results showed that (a) annual Tm, Tmax, and Tmin have a significant increasing trend with the increasing rates of 0.26, 0.15and 0.43 °C per <span class="hlt">decade</span>, respectively; (b) annual precipitation has an insignificant decreasing trend with the decreasing rate of 3.17 mm per <span class="hlt">decade</span>; (c) annual Hum has a significant decreasing trend in all seasons; and (d) there are two turning points for temperature rise around 1980 and 1995 and two abrupt change periods for precipitation with the extreme points appearing in 1963 and 1976. Temperature rise and precipitation decline in summer and autumn as well as wind speed decrease after the 1990s may be an important reason for algal blooms outbreak in Lake Dianchi. This study was expected to provide foundation and reference for regional water resource management.</p> <div class="credits"> <p class="dwt_author">Zhou, Jing; Liang, Zhongyao; Liu, Yong; Guo, Huaicheng; He, Dan; Zhao, Lei</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_12");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> 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showDiv("page_15");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">261</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=variables+AND+STAR&id=EJ200250"> <span id="translatedtitle"><span class="hlt">Observing</span> Simulated Cepheid <span class="hlt">Variable</span> Stars in an Introductory Astronomy Lab.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">Describes an exercise developed by the author to help college students to become familiar with the technique of photoelectric photometry of <span class="hlt">variable</span> stars and permits each student to work with data he or she has personally obtained. (HM)</p> <div class="credits"> <p class="dwt_author">Flesch, Terry R.</p> <p class="dwt_publisher"></p> <p class="publishDate">1979-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">262</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.phy.ohiou.edu/~mboett/integral5.ps.gz"> <span id="translatedtitle">COORDINATED MULTIWAVELENGTH <span class="hlt">OBSERVATIONS</span> AND SPECTRAL <span class="hlt">VARIABILITY</span> MODELING OF GAMMARAY BLAZARS</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">significantly constrain emission models and potential <span class="hlt">variability</span> scenarios. In the case of BL Lac­ ertae galactic nuclei; blazars; BL Lac­ ertae; jets; gamma­rays; multiwavelength observa­ tions; theory. 1</p> <div class="credits"> <p class="dwt_author">Boettcher, Markus</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">263</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014cosp...40E.466C"> <span id="translatedtitle">Two <span class="hlt">decades</span> of global and regional sea level <span class="hlt">observations</span> from the ESA climate change initiative sea sevel project</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Sea level is a very sensitive index of climate change and <span class="hlt">variability</span>. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level <span class="hlt">variability</span> and changes implies an accurate monitoring of the sea level <span class="hlt">variable</span> at climate scales, in addition to understanding the ocean <span class="hlt">variability</span> and the exchanges between ocean, land, cryosphere, and atmosphere. That is why Sea Level is one of the Essential Climate <span class="hlt">Variables</span> (ECV) selected in the frame of the ESA Climate Change Initiative (CCI) program. This program aims at providing long-term satellite-based products for climate (ECV products), that should be used by the climate research community. This program has just completed its first phase (Oct. 2010 to Dec. 2013) and will start in February 2014 the second phase of 3 years. The objective of the second phase are similar: to involve the climate research community to refine their needs and collect their feedbacks on product quality, to develop, test and select the best algorithms and standards to generate an updated climate time series and to produce and validate the Sea Level ECV product. This will better answer the climate user needs by improving the quality of the Sea Level products and maintain a sustain service for an up-to-date production. We will firstly present the main achievements of the ESA CCI Sea Level Project. On the one hand, the major steps required to produce the 18 years climate time series (delivered in Sept. 2012) are briefly described: collect and refine the user requirements, development of adapted algorithms for climate applications and specification of the production system. On the other hand, the product characteristics are described as well as the results from product validation, performed by several groups of the ocean and climate modeling community. At last, the work plan and key challenges of the second phase of the project are described.</p> <div class="credits"> <p class="dwt_author">Cazenave, Anny; Benveniste, Jérôme; Legeais, JeanFrancois</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">264</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014EGUGA..16.7675L"> <span id="translatedtitle">Two <span class="hlt">Decades</span> of Global and Regional Sea Level <span class="hlt">Observation</span> from the ESA Climate Change Initiative Sea Level Project</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Sea level is a very sensitive index of climate change and <span class="hlt">variability</span>. Sea level integrates the ocean warming, mountain glaciers and ice sheet melting. Understanding the sea level <span class="hlt">variability</span> and changes implies an accurate monitoring of the sea level <span class="hlt">variable</span> at climate scales, in addition to understanding the ocean <span class="hlt">variability</span> and the exchanges between ocean, land, cryosphere, and atmosphere. That is why Sea Level is one of the Essential Climate <span class="hlt">Variables</span> (ECV) selected in the frame of the ESA Climate Change Initiative (CCI) program. This program aims at providing long-term satellite-based products for climate (ECV products), that should be used by the climate research community. This program has just completed its first phase (Oct. 2010 to Dec. 2013) and will start in February 2014 the second phase of 3 years. The objective of the second phase are similar: to involve the climate research community to refine their needs and collect their feedbacks on product quality, to develop, test and select the best algorithms and standards to generate an updated climate time series and to produce and validate the Sea Level ECV product. This will better answer the climate user needs by improving the quality of the Sea Level products and maintain a sustain service for an up-to-date production. We will firstly present the main achievements of the ESA CCI Sea Level Project. On the one hand, the major steps required to produce the 18 years climate time series (delivered in Sept. 2012) are briefly described: collect and refine the user requirements, development of adapted algorithms for climate applications and specification of the production system. On the other hand, the product characteristics are described as well as the results from product validation, performed by several groups of the ocean and climate modeling community. At last, the work plan and key challenges of the second phase of the project are described.</p> <div class="credits"> <p class="dwt_author">Larnicol, Gilles; Cazenave, Anny; Ablain, Michael; Legeais, JeanFrancois; Faugere, Yannice; Benveniste, Jerome; Lucas, Bruno; Dinardo, Salvatore; Johannessen, Johnny; Stammer, Detlef; Timms, Gary; Knudsen, Per; Cipollini, Paolo; Roca, Monica; Rudenko, Sergei; Fernandes, Joana; Balmaseda, Magdalena; Guinle, Thierry</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">265</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/3153477"> <span id="translatedtitle">Global climate change and <span class="hlt">variability</span> and its influence on Alpine climate — concepts and <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The paper discusses annual to <span class="hlt">decadal</span> climate <span class="hlt">variability</span> and change in the European Alps by utilizing the procedure of synoptic downscaling, i.e. it investigates the influence of global to continental scale synoptic structures and processes on the regional climate of the Alps. The European Alps lie to the southeast and under the right exit zone of the southwest-northeast oriented axis</p> <div class="credits"> <p class="dwt_author">H. Wanner; R. Rickli; E. Salvisberg; C. Schmutz; M. Schüepp</p> <p class="dwt_publisher"></p> <p class="publishDate">1997-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">266</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2001AcAau..48..853W"> <span id="translatedtitle"><span class="hlt">Observations</span> from over a <span class="hlt">decade</span> of experience in developing faster, better, cheaper missions for the NASA small explorer program</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Small Explorer (SMEX) Project at NASA Goddard Space Flight Center (GSFC) has accumulated nearly a <span class="hlt">decade</span> of experience building missions with the underlying philosophy of "Faster, Better, Cheaper" (FBC). Five satellites are now successfully operating on-orbit with only one serious instrument anomaly. Together this Project has accumulated 14.6 years of on-orbit experience without a spacecraft bus failure. Additionally, this project, under the Explorer Technology Infusion effort, has developed a protoflight version of a 21 st Century FBC spacecraft bus that has just completed environmental qualification and has been selected at the base spacecraft for NASA's Triana mission. Design and production of these six high performance spacecraft, in just ten years time, has provided a unique base of experience from which to draw lessons learned. This paper will discuss the fundamental practices that have been used by the SMEX Project in achieving this record of success.</p> <div class="credits"> <p class="dwt_author">Watzin, Jim</p> <p class="dwt_publisher"></p> <p class="publishDate">2001-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">267</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://kuscholarworks.ku.edu/handle/1808/15872"> <span id="translatedtitle">Assessment of <span class="hlt">variability</span> in continental low stratiform clouds based on <span class="hlt">observations</span> of radar reflectivity</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">The <span class="hlt">variability</span> of overcast low stratiform clouds <span class="hlt">observed</span> over the ARM Climate Research Facility Southern Great Plains (ACRF SGP) site is analyzed, and an approach to characterizing subgrid <span class="hlt">variability</span> based on assumed statistical distributions...</p> <div class="credits"> <p class="dwt_author">Kogan, Zena N.; Mechem, David B.; Kogan, Yefim L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2005-09-22</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">268</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013EGUGA..15.5405K"> <span id="translatedtitle"><span class="hlt">Observation</span> of spiciness interannual <span class="hlt">variability</span> in the Pacific pycnocline</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Monthly gridded fields predominantly based on global Argo in situ temperature and salinity data are used to analyze the density-compensated anomaly of salinity (spiciness anomaly) in the pycnocline of the subtropical and tropical Pacific Ocean between 2004 and 2011. Interannual <span class="hlt">variability</span> in the formation, propagation and fate of spiciness anomalies are investigated. The spiciness anomalies propagate on the isopycnal surface ?? = 25.5 along the subtropical-tropical pycnocline advected by the mean currents. They reach the Pacific Western Tropics in about 5-6 years in the Southern Hemisphere and about 7-8 years in the Northern Hemisphere. Their amplitude strongly diminishes along the way and only very weak spiciness anomalies seem to reach the equator in the Western Tropics A complex-EOF analysis of interannual salinity anomalies on ?? = 25.5 highlights two dominant modes of <span class="hlt">variability</span> at interannual scale: i) the former shows a <span class="hlt">variability</span> of 5-7 years predominant in the Northern Hemisphere, and ii) the latter displays an interannual <span class="hlt">variability</span> of 2 to 3 years more marked in the Southern Hemisphere. The significant correlation of this second mode with ENSO index suggests that spiciness formation in the South-Eastern Pacific (SEP) is affected by ENSO tropical interannual <span class="hlt">variability</span>. A diagnosis of the mechanisms governing the interannual generation of spiciness in the SEP region leads the authors to suggest that the spiciness interannual <span class="hlt">variability</span> in the sub-surface is linked to the equatorward migration of the isopycnal outcrop line ?? = 25.5 into the area of maximum salinity. Quantitative analysis based on Turner angle reveals the dominance of the spiciness injection mechanism occurring through convective mixing at the base of mixed layer.</p> <div class="credits"> <p class="dwt_author">Kolodziejczyk, Nicolas; Gaillard, Fabienne</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">269</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..1214798A"> <span id="translatedtitle">Ozone column content <span class="hlt">variability</span> at the Kishinev site from satellite retrievals and ground <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">It is analyzed <span class="hlt">variability</span> of the total ozone content (TOC) in column of atmosphere by using ozone retrievals from satellite platform and from direct ground <span class="hlt">observations</span> at the Kishinev site, Moldova (47.00N; 28.56E). Direct ground <span class="hlt">observations</span> of the TOC are regular carried out by Atmospheric Research Group (ARG), Institute of Applied Physics at the ground-based solar radiation monitoring station, Kishinev site, by using of hand-held ozonemeter MICROTOPS II. TOC measurements started since 2003. Data of ozone <span class="hlt">observations</span> are presented at the research group web-site http://arg.phys.asm.md. Satellite TOC dataset at specific coordinates of Kishinev site was derived by using linear interpolation of the parent gridded databases from TOMS (1979-2004) and OMI (2005-2008) <span class="hlt">observations</span>. It was established that relative difference of TOC between periods from 1979 to 1983 and from 2004 to 2008 was -5.16 %. Data were processed by applying of 5-year averaging "window". For a period from 1979 to 2008 statistical estimation of linear trend of the TOC was -2.08% per <span class="hlt">decade</span>. Climatic norm of TOC for this period was equal to 335 DU. Variation of ozone column content at Kishinev site shows it seasonal character with maximum of the order of ~378 DU (in March and April) and with minimum of the order of ~289 DU (in October). The largest and lowest range of oscillations of monthly means of the TOC retrieved for Kishinev site from TOMS and OMI <span class="hlt">observations</span> in the course of the period from 1979 to 2008 were ~ 102 DU (in February) and ~29 DU (in October). Extremely low and high values of the TOC ever registered for Kishinev site from TOMS and OMI <span class="hlt">observations</span> were ~ 209 DU (on December 1, 1999) and ~ 532 DU (on March 3, 1988). It was shown that ARG ground <span class="hlt">observations</span> give overestimated TOC values in comparison with the TOMS and OMI <span class="hlt">observations</span> from satellite platforms. Relative differences or biases (in %) between satellite and ARG ground <span class="hlt">observations</span> of the TOC at Kishinev site were derived by using of daily means of TOC from the short-long series of simultaneous measurements for respective pairs: TOMS vs ARG (2003-2005) and OMI vs ARG(2004-2008). These differences were -1.85% (or -6 DU) for pair TOMS-ARG and -2.15% (or -7 DU) for pair OMI-ARG <span class="hlt">observations</span>. It should be noted that derived correlation coefficients for sets of TOMS-ARG and OMI-ARG <span class="hlt">observations</span> of daily means of TOC were ~0.981 and ~0.992, respectively.</p> <div class="credits"> <p class="dwt_author">Aculinin, Alexandr; Smicov, Vladimir</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">270</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012EGUGA..14..536P"> <span id="translatedtitle">Sea state <span class="hlt">variability</span> <span class="hlt">observed</span> by high resolution satellite radar images</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The spatial <span class="hlt">variability</span> of the wave parameters is measured and investigated using new TerraSAR-X (TS-X) satellite SAR (Synthetic Aperture Radar) images. Wave groupiness, refraction and breaking of individual wave are studied. Space borne SAR is a unique sensor providing two dimensional information of the ocean surface. Due to its daylight, weather independency and global coverage, the TS-X radar is particularly suitable for many ocean and coastal <span class="hlt">observations</span> and it acquires images of the sea surface with up to 1m resolution; individual ocean waves with wavelength below 30m are detectable. Two-dimensional information of the ocean surface, retrieved using TS-X data, is validated for different oceanographic applications: derivation of the fine resolved wind field (XMOD algorithm) and integrated sea state parameters (XWAVE algorithm). The algorithms are capable to take into account fine-scale effects in the coastal areas. This two-dimensional information can be successfully applied to validate numerical models. For this, wind field and sea state information retrieved from SAR images are given as input for a spectral numerical wave model (wind forcing and boundary condition). The model runs and sensitivity studies are carried out at a fine spatial horizontal resolution of 100m. The model results are compared to buoy time series at one location and with spatially distributed wave parameters obtained from SAR. The comparison shows the sensitivity of waves to local wind variations and the importance of local effects on wave behavior in coastal areas. Examples for the German Bight, North Sea and Rottenest Island, Australia are shown. The wave refraction, rendered by high resolution SAR images, is also studied. The wave ray tracking technique is applied. The wave rays show the propagation of the peak waves in the SAR-scenes and are estimated using image spectral analysis by deriving peak wavelength and direction. The changing of wavelength and direction in the rays allows detecting underwater structures (banks, reefs, shallows) and to obtain bathymetry in case a well-developed swell is imaged. Further, wave energy flux propagation towards the coast and its dissipation are obtained using the wave ray technique: wave height and wavelength are derived from TS-X image spectrum. The height of individual breaking waves is obtained from SAR-image signatures and it is compared to the model results and the buoy measurements. The results show some lower amplitude of the breaking waves, when compared to model results in the shoaling zone. This effect could be explained by an actual stronger dissipation than the one given by the model in the investigated area (coral reefs). Wave groups are detected for a cross sea and in storm condition in the ocean. The parameters of the wave groups are investigated and the conditions, which are responsible for their origin, are studied by numerical simulation using spectral wave model.</p> <div class="credits"> <p class="dwt_author">Pleskachevsky, A.; Lehner, S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">271</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/953845"> <span id="translatedtitle">Final Progress Report: Collaborative Research: <span class="hlt">Decadal</span>-to-Centennial Climate & Climate Change Studies with Enhanced <span class="hlt">Variable</span> and Uniform Resolution GCMs Using Advanced Numerical Techniques</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">The joint U.S-Canadian project has been devoted to: (a) <span class="hlt">decadal</span> climate studies using developed state-of-the-art GCMs (General Circulation Models) with enhanced <span class="hlt">variable</span> and uniform resolution; (b) development and implementation of advanced numerical techniques; (c) research in parallel computing and associated numerical methods; (d) atmospheric chemistry experiments related to climate issues; (e) validation of regional climate modeling strategies for nested- and stretched-grid models. The <span class="hlt">variable</span>-resolution stretched-grid (SG) GCMs produce accurate and cost-efficient regional climate simulations with mesoscale resolution. The advantage of the stretched grid approach is that it allows us to preserve the high quality of both global and regional circulations while providing consistent interactions between global and regional scales and phenomena. The major accomplishment for the project has been the successful international SGMIP-1 and SGMIP-2 (Stretched-Grid Model Intercomparison Project, phase-1 and phase-2) based on this research developments and activities. The SGMIP provides unique high-resolution regional and global multi-model ensembles beneficial for regional climate modeling and broader modeling community. The U.S SGMIP simulations have been produced using SciDAC ORNL supercomputers. Collaborations with other international participants M. Deque (Meteo-France) and J. McGregor (CSIRO, Australia) and their centers and groups have been beneficial for the strong joint effort, especially for the SGMIP activities. The WMO/WCRP/WGNE endorsed the SGMIP activities in 2004-2008. This project reflects a trend in the modeling and broader communities to move towards regional and sub-regional assessments and applications important for the U.S. and Canadian public, business and policy decision makers, as well as for international collaborations on regional, and especially climate related issues.</p> <div class="credits"> <p class="dwt_author">Fox-Rabinovitz, M; Cote, J</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-06-05</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">272</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2008JGRC..113.8039R"> <span id="translatedtitle"><span class="hlt">Decadal</span> <span class="hlt">variability</span> of East Australian Current transport inferred from repeated high-density XBT transects, a CTD survey and satellite altimetry</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A time series of the net geostrophic transport through the Tasman Sea (representing the flow of the East Australian Current (EAC) Extension) is determined from a full-depth CTD section, 15 years of high-density XBT transects, and satellite altimetry data. A section between Sydney and Wellington (PX34) has been occupied four times per year since 1991 with high resolution XBT sampling. Two methods to infer baroclinic transport from proxy data along the section are presented. The first uses shallow XBT transects to derive geostrophic transport relative to a deep (2000 m) reference level. In the second approach (SynTS) the subsurface temperature and salinity structure are inferred from satellite surface height and temperature fields using a model developed from historical in situ <span class="hlt">observations</span>. The baroclinic transport is then computed in the usual manner. The methods are validated using both a full-depth CTD occupation of the PX34 section and further transects crossing the EAC in the northern Tasman Sea. There is close agreement between the 49 XBT and SynTS PX34 transport estimates obtained between 1992 and 2006. The time series of transport through the Sydney-Wellington section shows a range of temporal signals from eddyscale, seasonal, interannnual to <span class="hlt">decadal</span>. In particular, we note that the net EAC flow ranges from 5 Sv in 1995 to a maximum of 16 Sv in 2000/2001. This <span class="hlt">decadal</span> variation confirms the EAC response to a spin-up of the South Pacific circulation forced by changes in the basin-wide winds and matches the changes in oceanic properties <span class="hlt">observed</span> in the Tasman Sea.</p> <div class="credits"> <p class="dwt_author">Ridgway, K. R.; Coleman, R. C.; Bailey, R. J.; Sutton, P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">273</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/21528851"> <span id="translatedtitle">Optimization of the transmission of <span class="hlt">observable</span> expectation values and <span class="hlt">observable</span> statistics in continuous-<span class="hlt">variable</span> teleportation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We analyze the statistics of <span class="hlt">observables</span> in continuous-<span class="hlt">variable</span> (CV) quantum teleportation in the formalism of the characteristic function. We derive expressions for average values of output-state <span class="hlt">observables</span>, in particular, cumulants which are additive in terms of the input state and the resource of teleportation. Working with a general class of teleportation resources, the squeezed-bell-like states, which may be optimized in a free parameter for better teleportation performance, we discuss the relation between resources optimal for fidelity and those optimal for different <span class="hlt">observable</span> averages. We obtain the values of the free parameter of the squeezed-bell-like states which optimize the central momenta and cumulants up to fourth order. For the cumulants the distortion between in and out states due to teleportation depends only on the resource. We obtain optimal parameters {Delta}{sub (2)}{sup opt} and {Delta}{sub (4)}{sup opt} for the second- and fourth-order cumulants, which do not depend on the squeezing of the resource. The second-order central momenta, which are equal to the second-order cumulants, and the photon number average are also optimized by the resource with {Delta}{sub (2)}{sup opt}. We show that the optimal fidelity resource, which has been found previously to depend on the characteristics of input, approaches for high squeezing to the resource that optimizes the second-order momenta. A similar behavior is obtained for the resource that optimizes the photon statistics, which is treated here using the sum of the squared differences in photon probabilities of input versus output states as the distortion measure. This is interpreted naturally to mean that the distortions associated with second-order momenta dominate the behavior of the output state for large squeezing of the resource. Optimal fidelity resources and optimal photon statistics resources are compared, and it is shown that for mixtures of Fock states both resources are equivalent.</p> <div class="credits"> <p class="dwt_author">Albano Farias, L.; Stephany, J. [Departamento de Fisica, Seccion de Fenomenos Opticos, Universidad Simon Bolivar, Apartado Postal 89000, Caracas 1080A (Venezuela, Bolivarian Republic of)</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-12-15</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">274</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://aosc.umd.edu/~seminar/data/y11spring/umd_aosc_110217_arkin.pdf"> <span id="translatedtitle"><span class="hlt">Observed</span> Global Precipitation <span class="hlt">Variability</span> During the 20th Century</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">is precipitation <span class="hlt">observed</span>? n The only direct, quantitative measurements come from rain gauges n Good absolute. A crucial role for <span class="hlt">observations</span>: validation of model simulations/predictions How do we evaluate simulations more accurate, IR better sampling n Gauges better absolute accuracy, poor sampling n Combination</p> <div class="credits"> <p class="dwt_author">Anisimov, Mikhail</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">275</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20040081179&hterms=africa+statistics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dafrica%2Bstatistics"> <span id="translatedtitle"><span class="hlt">Variability</span> in Tropical Tropospheric Ozone as <span class="hlt">Observed</span> by SHADOZ</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The SHADOZ (Southern Hemisphere Additional Ozonesondes) ozone sounding network was initiated in 1998 to improve the coverage of tropical in-situ ozone measurements for satellite validation, algorithm development and related process studies. Over 2000 soundings have been archived at the central website, <http://croc.gsfc.nasa.gov/shadoz>, for 12 stations: Ascension Island; Nairobi and Malindi, Kenya; Irene, South Africa; Reunion Island; Watukosek, Java; Fiji; Tahiti; American Samoa; San Cristobal, Galapagos; Natal, Brazil; Paramaribo, Surinam. Some results to date indicate reliability of the measurement and highly <span class="hlt">variable</span> interactions between ozone and tropical meteorology. For example: 1. By using ECC sondes with similar procedures, 5-10% accuracy and precision (1-sigma) of the sonde total ozone measurement was achieved [Thompson et al., 2003al; 2. Week-to-week <span class="hlt">variability</span> in tropospheric ozone is so great that statistics are frequently not Gaussian and most stations vary up to a factor of 3 in column amount over the course of a year [Thompson et al., 2002b]. 3. Longitudinal <span class="hlt">variability</span> in tropospheric ozone profiles is a consistent feature, with a 10- 15 DU column-integrated difference between Atlantic and Pacific sites; this is the cause of the zonal wave-one feature in total ozone [Shiotani, 1992]. The ozone record from Paramaribo, Surinam (6N, 55W) is a marked contrast to southern tropical ozone because Surinam is often north of the Intertropical Convergence Zone. Interpretations of SHADOZ time-series and approaches to classification suggested by SHADOZ data over Africa and the Indian Ocean will be described.</p> <div class="credits"> <p class="dwt_author">Thompson, Anne M.; Witte, Jacquelyn C.; Coetzee, Geert J. R.; Chatfield, Robert B.; Hudson, Robert D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2004-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">276</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20120013038&hterms=Kepler+Laws&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3D%2528%2528Kepler%2Bs%2529%2BLaws%2529"> <span id="translatedtitle">Kepler <span class="hlt">Observations</span> of Rapid Optical <span class="hlt">Variability</span> in Active Galactic Nuclei</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Over three quarters in 2010 - 2011, Kepler monitored optical emission from four active galactic nuclei (AGN) with approx 30 min sampling, > 90% duty cycle and approx < 0.1% repeatability. These data determined the AGN optical fluctuation power spectral density functions (PSDs) over a wide range in temporal frequency. Fits to these PSDs yielded power law slopes of -2.6 to -3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGN exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN <span class="hlt">variability</span> models but seem consistent with first order MRI theoretical calculations of accretion disk fluctuations.</p> <div class="credits"> <p class="dwt_author">Mushotzky, R. F.; Edelson, R.; Baumgartner, W. H.; Gandhi, P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">277</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19730007141&hterms=star+sun&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dstar%2Bsun"> <span id="translatedtitle"><span class="hlt">Observations</span> of the sun, an ultraviolet <span class="hlt">variable</span> star</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The uncertainty as to whether or not the sun is a <span class="hlt">variable</span> star in that region of the ultraviolet which is absorbed in the mesosphere and stratosphere led to an experiment with acronym MUSE, Monitor of Ultraviolet Solar Energy. The experiment was first flown on an Aerobee rocket in August 1966 and subsequently on Nimbus 3 and 4 in April 1969 and April 1970 respectively. The basic philosophy behind the design of the experiment was to provide an instrument which would not require a solar pointing mechanism and at the same time would be capable of high radiometric accuracy for long periods in space.</p> <div class="credits"> <p class="dwt_author">Heath, D. F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1972-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">278</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ngm.nationalgeographic.com/2007/09/vesuvius/decade-volcano-map-interactive"> <span id="translatedtitle"><span class="hlt">Decade</span> Volcanoes</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">In the 1990s, the International Association of Volcanology and Chemistry of the Earth's Interior started the <span class="hlt">Decade</span> Volcano Project. As part of their work, they designated sixteen volcanoes particularly worthy of study "because of their explosive histories and close proximity to human populations." The group recently teamed up with National Geographic to create a guide to these volcanoes via this interactive map. Navigating through the map, visitors can learn about Mount Rainier, Colima, Galeras, Santorini, and other prominent volcanoes. For each volcano, there's a brief sketch that gives the date of its last eruption, its elevation, nearby population centers, and a photograph.</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">279</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/1030607"> <span id="translatedtitle">Towards the Prediction of <span class="hlt">Decadal</span> to Centennial Climate Processes in the Coupled Earth System Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">In this proposal, we have made major advances in the understanding of <span class="hlt">decadal</span> and long term climate <span class="hlt">variability</span>. (a) We performed a systematic study of multidecadal climate <span class="hlt">variability</span> in FOAM-LPJ and CCSM-T31, and are starting exploring <span class="hlt">decadal</span> <span class="hlt">variability</span> in the IPCC AR4 models. (b) We develop several novel methods for the assessment of climate feedbacks in the <span class="hlt">observation</span>. (c) We also developed a new initialization scheme DAI (Dynamical Analogue Initialization) for ensemble <span class="hlt">decadal</span> prediction. (d) We also studied climate-vegetation feedback in the <span class="hlt">observation</span> and models. (e) Finally, we started a pilot program using Ensemble Kalman Filter in CGCM for <span class="hlt">decadal</span> climate prediction.</p> <div class="credits"> <p class="dwt_author">Zhengyu Liu, J. E. Kutzbach, R. Jacob, C. Prentice</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-05</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">280</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20140007330&hterms=learning&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dlearning"> <span id="translatedtitle">Use of Machine Learning Techniques for Iidentification of Robust Teleconnections to East African Rainfall <span class="hlt">Variability</span> in <span class="hlt">Observations</span> and Models</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Providing advance warning of East African rainfall variations is a particular focus of several groups including those participating in the Famine Early Warming Systems Network. Both seasonal and long-term model projections of climate <span class="hlt">variability</span> are being used to examine the societal impacts of hydrometeorological <span class="hlt">variability</span> on seasonal to interannual and longer time scales. The NASA / USAID SERVIR project, which leverages satellite and modeling-based resources for environmental decision making in developing nations, is focusing on the evaluation of both seasonal and climate model projections to develop downscaled scenarios for using in impact modeling. The utility of these projections is reliant on the ability of current models to capture the embedded relationships between East African rainfall and evolving forcing within the coupled ocean-atmosphere-land climate system. Previous studies have posited relationships between variations in El Niño, the Walker circulation, Pacific <span class="hlt">decadal</span> <span class="hlt">variability</span> (PDV), and anthropogenic forcing. This study applies machine learning methods (e.g. clustering, probabilistic graphical model, nonlinear PCA) to <span class="hlt">observational</span> datasets in an attempt to expose the importance of local and remote forcing mechanisms of East African rainfall <span class="hlt">variability</span>. The ability of the NASA Goddard Earth <span class="hlt">Observing</span> System (GEOS5) coupled model to capture the associated relationships will be evaluated using Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations.</p> <div class="credits"> <p class="dwt_author">Roberts, J. Brent; Robertson, Franklin R.; Funk, Chris</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_13");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a 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href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a style="font-weight: bold;">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_16");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">281</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19740012549&hterms=exhaust+muffler&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dexhaust%2Bmuffler"> <span id="translatedtitle">Component noise <span class="hlt">variables</span> of a light <span class="hlt">observation</span> helicopter</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">A test program was conducted to isolate and evaluate the individual noise sources of a light helicopter. To accomplish this, the helicopter was mounted on a special test rig, at a 6-foot skid height, in a simulated hover. The test rig contained by dynamometer for absorbing engine power and an exhaust silencing system for reducing engine noise. This test set-up allowed the various components of the helicopter to be run and listened to individually or in any combination. The sound pressure level was recorded at a point 200 feet from the helicopter as the component parameters were systematically varied. The tests were conducted in an open area, during the middle of the night, with no wind, and with all other known <span class="hlt">variables</span> either eliminated or kept as constant as possible.</p> <div class="credits"> <p class="dwt_author">Robinson, F.</p> <p class="dwt_publisher"></p> <p class="publishDate">1973-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">282</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22047308"> <span id="translatedtitle">KEPLER <span class="hlt">OBSERVATIONS</span> OF RAPID OPTICAL <span class="hlt">VARIABILITY</span> IN ACTIVE GALACTIC NUCLEI</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Over three quarters in 2010-2011, Kepler monitored optical emission from four active galactic nuclei (AGNs) with {approx}30 minute sampling, >90% duty cycle, and {approx}<0.1% repeatability. These data determined the AGN optical fluctuation power spectral density (PSD) functions over a wide range in temporal frequency. Fits to these PSDs yielded power-law slopes of -2.6 to -3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGNs exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN <span class="hlt">variability</span> models but seem consistent with first-order magnetorotational instability theoretical calculations of accretion disk fluctuations.</p> <div class="credits"> <p class="dwt_author">Mushotzky, R. F.; Edelson, R. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Baumgartner, W. [Laboratory for High Energy Astrophysics, NASA/GSFC, Code 662, Greenbelt, MD 20771 (United States); Gandhi, P., E-mail: richard@astro.umd.edu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-12-10</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">283</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2001LNP...563..151M"> <span id="translatedtitle"><span class="hlt">Observations</span> of cataclysmic <span class="hlt">variable</span> and double degenerate stars</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The author discusses cataclysmic <span class="hlt">variable</span> stars and close pairs of white dwarfs or "double degenerates". These stars are connected through their evolution. The author begins by looking first at the method of "eclipse mapping" to address the problem of understanding light curves of systems with discs, next at "Doppler tomography", which deals with line emission. The emphasis of these sections is on the disk-accreting systems, and to redress the balance the author then considers the magnetic accretors, for which similar techniques have been applied in more recent years. Finally he discusses the evolution of close binaries by focusing upon near-relatives of CV's in evolutionary terms, close pairs of white dwarfs.</p> <div class="credits"> <p class="dwt_author">Marsh, Tom R.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">284</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/48951736"> <span id="translatedtitle">On the causes of plasmaspheric rotation <span class="hlt">variability</span>: IMAGE EUV <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">IMAGE EUV <span class="hlt">observations</span> demonstrate that the plasmasphere usually does not corotate as assumed in simple convection models, even at low L shells. We carry out a statistical survey of plasmaspheric rotation rates over several months of IMAGE EUV data in 2001, using two different measurement techniques. We test the prevailing hypothesis, that subcorotation is due to enhanced auroral zone Joule</p> <div class="credits"> <p class="dwt_author">David A. Galvan; Mark B. Moldwin; Bill R. Sandel; Geoff Crowley</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">285</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010EGUGA..1211648C"> <span id="translatedtitle">Nonlinear and stochastic effects in ENSO <span class="hlt">variability</span>: From <span class="hlt">observations</span> to intermediate models</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The El-Nino/Southern-Oscillation (ENSO) phenomenon dominates interannual climate signals in and around the Tropical Pacific and affects the atmospheric circulation and air-sea interaction over many parts of the globe. <span class="hlt">Observational</span> campaigns over the last <span class="hlt">decades</span> have helped infer the most relevant processes, time scales and spatial patterns. A hierarchy of models has been developed to understand these processes and their interaction. These models have been, by-and-large, either deterministic and nonlinear or stochastic and linear, and have been applied to the prediction of future <span class="hlt">variability</span> as well. The purpose of our work is to combine these two complementary points of view, and thus account for (i) the most robust and relevant aspects of the <span class="hlt">observations</span>; (ii) the advances in understanding the nonlinear, deterministic interactions between the largest and most energetic scales; and (iii) the impact of small-scale ("noise") and remote ("external") processes. The main thrust of our approach is based on the concepts and tools of the theory of random dynamical systems (RDS). So far, two of the co-authors (MC & MG), in collaboration with E. Simonnet, have successfully applied RDS theory to, and described in detail the random attractors of several idealized climate models, such as the Lorenz (JAS, 1963) model of convection and the ENSO model of Timmermann and Jin (GRL, 2002). In the present work, we are extending these results to more detailed and realistic models, on the way to their eventual application to IPCC-class general circulation models (GCMs). Specifically, we address here two classes of such intermediate models. The first class is that of nonlinear inverse models derived by empirical mode reduction (EMR), as developed by two of the co-authors (MG and DK), in collaboration with S. Kravtsov, A. W. Robertson and others. In particular, we are studying the random attractor of the ENSO model derived in 2005 from sea surface temperature data over the past century, and being routinely applied to ENSO prediction since. The second class is that of intermediate models developed by one of the coauthors (JDN) in the early 1990s. These models are based on thermodynamical and fluid mechanical principles classically used in ENSO theory. This particular model has also been used over several years in routine ENSO prediction, as summarized over two <span class="hlt">decades</span> by NOAA's Experimental Long-Lead Forecast Bulletin (ELLFB) and, more recently, by the "ENSO prediction plume" of the International Research Institute for Climate and Society (IRI). In both types of intermediate models, we study the effects of stochastic forcing that exhibits spatial correlations with the twofold purpose of (i) helping parameterize the unresolved processes, and (ii) improving prediction capabilities.</p> <div class="credits"> <p class="dwt_author">Chekroun, Mickael David; Kondrashov, Dmitri; Neelin, David; Ghil, Michael</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">286</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014AAS...22421904C"> <span id="translatedtitle">The Semiregular <span class="hlt">Variable</span> Star <span class="hlt">Observing</span> Program at Grinnell College</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A large body of photometric and spectroscopic data on 38 semiregular <span class="hlt">variable</span> stars has been acquired at the Grant O. Gale Observatory of Grinnell College since 1984. This includes V and B band photoelectric photometry, CCD spectroscopic monitoring, and a large set of spectra for RS Cygni. The stars in the program were selected because they had a history of “quiescent episodes” in their pulsations that might be explained as mode switches. Time-dependent Fourier analysis has been applied to the photometric data to reveal the dominant frequency components represented in the light curves and to investigate how the strengths of those components vary - sometimes quite abruptly - over time. The spectroscopic monitoring of the entire set of stars is an ongoing project. The 413 RS Cygni spectra have been used to explore the variation of spectral features with phase. The conspicuous dip near the peak of the RS Cygni light curve does not appear to be associated with obvious variations in the strengths of spectral features.</p> <div class="credits"> <p class="dwt_author">Cadmus, Robert R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">287</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012cosp...39.1770S"> <span id="translatedtitle"><span class="hlt">Variability</span> of trace gas concentrations over Asian region: satellite <span class="hlt">observations</span> vs model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Nitrogen dioxide (NO_2) and Carbon Monoxide (CO) play a key role in the chemistry of the tropospheric ozone and are emitted mainly by anthropogenic processes. These emissions have been increasing over Asia over the past few years due to rapid economic growth and yet there are very few systematic ground based <span class="hlt">observations</span> of these species over this region. We have analysed ten years of data from space borne instruments: Global Ozone Monitoring Experiment (GOME), SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and Measurements of Pollution in the Troposphere (MOPITT), which have been measuring the tropospheric abundance of these trace gases. We have examined trends over the period 1996-2008 in NO_2 and CO over a few Indian regions where high economic growth in the present <span class="hlt">decade</span> is likely to see increased emissions for these species. However, even the highest growth rate of these species seen in the present study, is less when compared with similar polluted regions of China, where a much more rapid increase has been <span class="hlt">observed</span>. In order to understand the trends and <span class="hlt">variability</span> in atmospheric trace gas concentrations, one must take into account changes in emissions and transport. Only by assessing the relevance of each of these factors will it be possible to predict future changes with reasonable confidence. To this effect we have used a global chemical transport model, MOZART, to simulate concentrations of NO_2 and CO using the POET (European) and REAS (Asian) emission inventories. These are compared with satellite measurements to study seasonal variations and the discrepancies are discussed. The combined uncertainties of the emission inventory and retrieval of the satellite data could be contributing factors to the discrepancies. It may be thus worthwhile to develop emission inventories for India at a higher resolution to include local level activity data.</p> <div class="credits"> <p class="dwt_author">Sheel, Varun; Richter, Andreas; Srivastava, Shuchita; Lal, Shyam</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">288</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23777769"> <span id="translatedtitle">Improvements in <span class="hlt">observed</span> and relative survival in follicular grade 1-2 lymphoma during 4 <span class="hlt">decades</span>: the Stanford University experience.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Recent studies report an improvement in overall survival (OS) of patients with follicular lymphoma (FL). Previously untreated patients with grade 1 to 2 FL treated at Stanford University from 1960-2003 were identified. Four eras were considered: era 1, pre-anthracycline (1960-1975, n = 180); era 2, anthracycline (1976-1986, n = 426); era 3, aggressive chemotherapy/purine analogs (1987-1996, n = 471); and era 4, rituximab (1997-2003, n = 257). Clinical characteristics, patterns of care, and survival were assessed. <span class="hlt">Observed</span> OS was compared with the expected OS calculated from Berkeley Mortality Database life tables derived from population matched by gender and age at the time of diagnosis. The median OS was 13.6 years. Age, gender, and stage did not differ across the eras. Although primary treatment varied, event-free survival after the first treatment did not differ between eras (P = .17). Median OS improved from 11 years in eras 1 and 2 to 18.4 years in era 3 and has not yet been reached for era 4 (P < .001), with no suggestion of a plateau in any era. These improvements in OS exceeded improvements in survival in the general population during the same period. Several factors, including better supportive care and effective therapies for relapsed disease, are likely responsible for this improvement. PMID:23777769</p> <div class="credits"> <p class="dwt_author">Tan, Daryl; Horning, Sandra J; Hoppe, Richard T; Levy, Ronald; Rosenberg, Saul A; Sigal, Bronislava M; Warnke, Roger A; Natkunam, Yasodha; Han, Summer S; Yuen, Alan; Plevritis, Sylvia K; Advani, Ranjana H</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">289</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2006AGUSM.A41A..02T"> <span id="translatedtitle"><span class="hlt">Variability</span> in Tropospheric Ozone <span class="hlt">Observed</span> Through Ozone Soundings</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Profiles from ozonesondes (taken with electrochemical concentration cell instruments, simultaneously with radiosondes for pressure, temperature and humidity data) record ozone concentration at 5 m resolution from the surface to 5-10 hPa. These measurements, taken regularly (normally weekly) at stations worldwide, are vital for ground-truthing satellites, studying processes like the "ozone hole" and determining trends. The co- authors have operated the two long-term US ozonesonde stations (in Colorado http://www.cmdl.noaa.gov/ozwv/ozsondes/ and Virginia http://uairp.wff.nasa.gov) and designed networks for specific scientific purposes. Two such networks, the SHADOZ tropical network http://croc.gsfc.nasa.gov/shadoz, operating since 1998 and the short-term IONS mid-latitude network, http://croc.gsfc.nasa.gov/intex/ions.html, in 2004 and 2006, have been invaluable for investigating tropospheric processes and trends. In this paper, examples will be presented from the following: - Classification of ozone profiles by statistical methods for mid- and tropical latitudes. Coherence with meteorological patterns is a better way than standard "means" to study interannual <span class="hlt">variability</span>. - Budget analysis: quantified contributions of deep convection, stratospheric exchange and pollution advection in UT/LS (upper troposphere-lower stratosphere) ozone over North America. - Interaction of chemical pollution and climate dynamics in tropical ozone; signatures of El Nino episodes and the Madden-Julian Oscillation are clear. - Trends in upper tropospheric ozone distributions in the tropics, from the 1980's to the present. Modified convection patterns appear to correlate with the change.</p> <div class="credits"> <p class="dwt_author">Thompson, A. M.; Stone, J. B.; Miller, S. K.; Witte, J. C.; Oltmans, S. J.; Schmidlin, F. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-05-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">290</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19760030096&hterms=variables+STAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dvariables%2BSTAR"> <span id="translatedtitle">Combined optical and X-ray <span class="hlt">observations</span> of <span class="hlt">variable</span> stars</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Questions concerning the optical identification of X-ray sources are considered. There are now a total of eight optically identified galactic X-ray sources. Of these eight, five are definitely established as binaries. The nature of the other three sources remains unknown. Studies of U Geminorum conducted on the basis of optical and X-ray <span class="hlt">observations</span> are also discussed. From the upper limit to the accretion rate for U Gem obtained with the aid of soft X-ray data, it is seen that most of the mass flow in U Gem is lost from the system.</p> <div class="credits"> <p class="dwt_author">Bowyer, C. S.</p> <p class="dwt_publisher"></p> <p class="publishDate">1975-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">291</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/1087698"> <span id="translatedtitle"><span class="hlt">Observed</span> Multi-<span class="hlt">Decade</span> DD and DT Z-Pinch Fusion Rate Scaling in 5 Dense Plasma Focus Fusion Machines</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">Dense Plasma Focus (DPF) machines are in use worldwide or a wide variety of applications; one of these is to produce intense, short bursts of fusion via r-Z pinch heating and compression of a working gas. We have designed and constructed a series of these, ranging from portable to a maximum energy storage capacity of 2 MJ. Fusion rates from 5 DPF pulsed fusion generators have been measured in a single laboratory using calibrated activation detectors. Measured rates range from ~ 1015 to more than 1019 fusions per second have been measured. Fusion rates from the intense short (20 – 50 ns) periods of production were inferred from measurement of neutron production using both calibrated activation detectors and scintillator-PMT neutron time of flight (NTOF) detectors. The NTOF detectors are arranged to measure neutrons versus time over flight paths of 30 Meters. Fusion rate scaling versus energy and current will be discussed. Data showing <span class="hlt">observed</span> fusion cutoff at D-D fusion yield levels of approximately 1?1012, and corresponding tube currents of ~ 3 MA will be shown. Energy asymmetry of product neutrons will also be discussed. Data from the NTOF lines of sight have been used to measure energy asymmetries of the fusion neutrons. From this, center of mass energies for the D(d,n)3He reaction are inferred. A novel re-entrant chamber that allows extremely high single pulse neutron doses (> 109 neutrons/cm2 in 50 ns) to be supplied to samples will be described. Machine characteristics and detector types will be discussed.</p> <div class="credits"> <p class="dwt_author">Hagen, E. C. [National Security Technologies, LLC; Lowe, D. R. [National Security Technologies, LLC; O'Brien, R. [University of Nevada, Las Vegas; Meehan, B. T. [National Security Technologies, LLC</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-06-18</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">292</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGRB..119.8366P"> <span id="translatedtitle">Insights into mantle structure and flow beneath Alaska based on a <span class="hlt">decade</span> of <span class="hlt">observations</span> of shear wave splitting</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">SKS shear wave splitting measurements from three Program for Array Seismic Studies of the Continental Lithosphere experiments (Broadband Experiment Across the Alaska Range, Alaska Receiving Cross Transect of the Inner Core, and Multidisciplinary <span class="hlt">Observations</span> Of Subduction), which form a north/south transect across Alaska, show a remarkably simple pattern of two large anisotropy domains. In the northern domain, extending from the 70 km contour of the subducting Pacific plate north to the Arctic Ocean, fast directions are consistently in the NE-SW direction. These directions are essentially parallel to the absolute plate motion direction in northern Alaska and parallel to the strike of the subducting plate above the mantle wedge, suggesting that they represent some combination of plate-scale asthenospheric flow in the upper mantle and flow along the subducting plate in the mantle wedge. A strong wedge component beneath the Alaska Range is required to explain systematics of splitting delay times. In the southern domain, which extends south from the 70 km depth contour to the subducting plate, fast directions are in the NW-SE direction, a 90° rotation from the northern domain. These fast directions are parallel to the dip of the subducting plate in the direction of convergence and represent entrained flow beneath the subducting slab; the Pacific Plate absolute motion approximately parallels local convergence. Two major factors seem to control flow in these regions, absolute plate motion in the north and the subduction of the Pacific plate in the south, although both subduction-driven wedge flow and absolute plate motion contribute to the southern part of the northern regime.</p> <div class="credits"> <p class="dwt_author">Perttu, Anna; Christensen, Douglas; Abers, Geoffrey; Song, Xiaodong</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-11-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">293</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20140016841&hterms=earthquakes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dearthquakes"> <span id="translatedtitle">Source Parameter Inversion for Recent Great Earthquakes from a <span class="hlt">Decade</span>-long <span class="hlt">Observation</span> of Global Gravity Fields</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We quantify gravity changes after great earthquakes present within the 10 year long time series of monthly Gravity Recovery and Climate Experiment (GRACE) gravity fields. Using spherical harmonic normal-mode formulation, the respective source parameters of moment tensor and double-couple were estimated. For the 2004 Sumatra-Andaman earthquake, the gravity data indicate a composite moment of 1.2x10(exp 23)Nm with a dip of 10deg, in agreement with the estimate obtained at ultralong seismic periods. For the 2010 Maule earthquake, the GRACE solutions range from 2.0 to 2.7x10(exp 22)Nm for dips of 12deg-24deg and centroid depths within the lower crust. For the 2011 Tohoku-Oki earthquake, the estimated scalar moments range from 4.1 to 6.1x10(exp 22)Nm, with dips of 9deg-19deg and centroid depths within the lower crust. For the 2012 Indian Ocean strike-slip earthquakes, the gravity data delineate a composite moment of 1.9x10(exp 22)Nm regardless of the centroid depth, comparing favorably with the total moment of the main ruptures and aftershocks. The smallest event we successfully analyzed with GRACE was the 2007 Bengkulu earthquake with M(sub 0) approx. 5.0x10(exp 21)Nm. We found that the gravity data constrain the focal mechanism with the centroid only within the upper and lower crustal layers for thrust events. Deeper sources (i.e., in the upper mantle) could not reproduce the gravity <span class="hlt">observation</span> as the larger rigidity and bulk modulus at mantle depths inhibit the interior from changing its volume, thus reducing the negative gravity component. Focal mechanisms and seismic moments obtained in this study represent the behavior of the sources on temporal and spatial scales exceeding the seismic and geodetic spectrum.</p> <div class="credits"> <p class="dwt_author">Han, Shin-Chan; Riva, Ricccardo; Sauber, Jeanne; Okal, Emile</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">294</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3869725"> <span id="translatedtitle">Demographic <span class="hlt">Variables</span> for Wild Asian Elephants Using Longitudinal <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Detailed demographic data on wild Asian elephants have been difficult to collect due to habitat characteristics of much of the species’ remaining range. Such data, however, are critical for understanding and modeling population processes in this endangered species. We present data from six years of an ongoing study of Asian elephants (Elephas maximus) in Uda Walawe National Park, Sri Lanka. This relatively undisturbed population numbering over one thousand elephants is individually monitored, providing cohort-based information on mortality and reproduction. Reproduction was seasonal, such that most births occurred during the long inter-monsoon dry season and peaked in May. During the study, the average age at first reproduction was 13.4 years and the 50th percentile inter-birth interval was approximately 6 years. Birth sex ratios did not deviate significantly from parity. Fecundity was relatively stable throughout the <span class="hlt">observed</span> reproductive life of an individual (ages 11–60), averaging between 0.13–0.17 female offspring per individual per year. Mortalities and injuries based on carcasses and disappearances showed that males were significantly more likely than females to be killed or injured through anthropogenic activity. Overall, however, most <span class="hlt">observed</span> injuries did not appear to be fatal. This population exhibits higher fecundity and density relative to published estimates on other Asian elephant populations, possibly enhanced by present range constriction. Understanding the factors responsible for these demographic dynamics can shed insight on the future needs of this elephant population, with probable parallels to other populations in similar settings. PMID:24376581</p> <div class="credits"> <p class="dwt_author">de Silva, Shermin; Webber, C. Elizabeth; Weerathunga, U. S.; Pushpakumara, T. V.; Weerakoon, Devaka K.; Wittemyer, George</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">295</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20130013062&hterms=air+asia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dair%2Basia"> <span id="translatedtitle">Interannual <span class="hlt">Variability</span> of OLR as <span class="hlt">Observed</span> by AIRS and CERES</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The paper examines spatial anomaly time series of Outgoing Longwave Radiation (OLR) and Clear Sky OLR (OLR(sub CLR)) as determined using <span class="hlt">observations</span> from CERES Terra and AIRS over the time period September 2002 through June 2011. We find excellent agreement of the two OLR data sets in almost every detail down to the x11deg spatial grid point level. The extremely close agreement of OLR anomaly time series derived from <span class="hlt">observations</span> by two different instruments implies high stability of both sets of results. Anomalies of global mean, and especially tropical mean, OLR are shown to be strongly correlated with an El Nino index. These correlations explain that the recent global and tropical mean decreases in OLR over the time period studied are primarily the result of a transition from an El Nino condition at the beginning of the data record to La Nina conditions toward the end of the data period. We show that the close correlation of mean OLR anomalies with the El Nino Index can be well accounted for by temporal changes of OLR within two spatial regions, one to the east of, and one to the west of, the NOAA Nino-4 region. Anomalies of OLR in these two spatial regions are both strongly correlated with the El Nino Index as a result of the strong anti-correlation of anomalies of cloud cover and mid-tropospheric water vapor in these two regions with the El Nino Index.</p> <div class="credits"> <p class="dwt_author">Susskind, Joel; Molnar, Gyula I.; Iredell, Lena F.; Loeb, Norman G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">296</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://wwwpaztcn.wr.usgs.gov/julio_pdf/Swetnam_Betancourt.pdf"> <span id="translatedtitle">3128 VOLUME 11J O U R N A L O F C L I M A T E Mesoscale Disturbance and Ecological Response to <span class="hlt">Decadal</span> Climatic <span class="hlt">Variability</span> in the</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">to <span class="hlt">Decadal</span> Climatic <span class="hlt">Variability</span> in the American Southwest THOMAS W. SWETNAM Laboratory of Tree-Ring Research in tree demography (births and deaths). Multicentury, tree-ring reconstructions of drought, disturbance inferred from independent tree-ring width, ice core, and coral isotope reconstructions. Episodic dry</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">297</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20120012822&hterms=air+asia&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dair%2Basia"> <span id="translatedtitle">Interannual <span class="hlt">Variability</span> of OLR as <span class="hlt">Observed</span> by AIRS and CERES</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">This paper compares spatial anomaly time series of OLR (Outgoing Longwave Radiation) and OLR(sub CLR) (Clear Sky OLR) as determined using <span class="hlt">observations</span> from CERES Terra and AIRS over the time period September 2002 through June 2011. Both AIRS and CERES show a significant decrease in global mean and tropical mean OLR over this time period. We find excellent agreement of the anomaly time-series of the two OLR data sets in almost every detail, down to 1 deg X 1 deg spatial grid point level. The extremely close agreement of OLR anomaly time series derived from <span class="hlt">observations</span> by two different instruments implies that both sets of results must be highly stable. This agreement also validates to some extent the anomaly time series of the AIRS derived products used in the computation of the AIRS OLR product. The paper also examines the correlations of anomaly time series of AIRS and CERES OLR, on different spatial scales, as well as those of other AIRS derived products, with that of the NOAA Sea Surface Temperature (SST) product averaged over the NOAA Nino-4 spatial region. We refer to these SST anomalies as the El Nino Index. Large spatially coherent positive and negative correlations of OLR anomaly time series with that of the El Nino Index are found in different spatial regions. Anomalies of global mean, and especially tropical mean, OLR are highly positively correlated with the El Nino Index. These correlations explain that the recent global and tropical mean decreases in OLR over the period September 2002 through June 2011, as <span class="hlt">observed</span> by both AIRS and CERES, are primarily the result of a transition from an El Nino condition at the beginning of the data record to La Nina conditions toward the end of the data period. We show that the close correlation of global mean, and especially tropical mean, OLR anomalies with the El Nino Index can be well accounted for by temporal changes of OLR within two spatial regions which lie outside the NOAA Nino-4 region, in which anomalies of cloud cover and mid-tropospheric water vapor are both highly negatively correlated with the El Nino Index. Agreement of the AIRS and CERES OLR(sub CLR) anomaly time series is less good, which may be a result of the large sampling differences in the ensemble of cases included in each OLR(sub CLR) data set.</p> <div class="credits"> <p class="dwt_author">Susskind, Joel; Molnar, Gyula; Iredell, Lena; Loeb, Norman G.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">298</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014IAUS..304...39K"> <span id="translatedtitle">New Spectral <span class="hlt">Observations</span> of the <span class="hlt">Variable</span> Galaxy Kaz 163</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Kaz 163 is a close double galaxy. Its southern component S is compact, with a very blue nucleus, in which heated active processes take place. From time to time gas formations are ejected from it, which behave themselves like emission components around the main emission lines H? and H?, around both from their long-wave and short-wave sides. This paper presents the spectral data of new <span class="hlt">observations</span>, which were carried out with the 2.6m telescope at the Byurakan Astrophysical Observatory in September 2011. During the former <span class="hlt">observation</span> in October 1981, lines [NII] ?? 6584,6548 were not visible in the spectrum of the component S. In 2001 they were already visible on the spectrum, and on the spectrum obtained in 2011 they already surpassed the intensity of H?. The magnitude of the component S is also changing: its nucleus is very blue and its U-B = -0 m .63. In the soft X-ray spectral range (0.1-2 keV) the flux of the radiation changed by 45% during 55,000 sec, and in the hard one (2-10keV) it changed up to 3.4 times. Photoindices ? for the soft and hard ranges in the spectrum of galaxy S, unlike other objects, do not so much differ from each other. The mean value for the first interval is approximately 2.5 and is equal -2.0 for the second one. On the histogram of redshifts Kaz 163 corresponds to the first big peak of the distribution. It is concluded that the component S of the galaxy Kaz 163 is a NLS1 galaxy, with the development of their evolution, is in the preliminary stage. Component N is a normal elliptical galaxy with no activity.</p> <div class="credits"> <p class="dwt_author">Karapetyan, Emilia L.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">299</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JVGR..289...51W"> <span id="translatedtitle"><span class="hlt">Decadal</span>-scale <span class="hlt">variability</span> of diffuse CO2 emissions and seismicity revealed from long-term monitoring (1995-2013) at Mammoth Mountain, California, USA</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Mammoth Mountain, California, is a dacitic volcano that has experienced several periods of unrest since 1989. The onset of diffuse soil CO2 emissions at numerous locations on the flanks of the volcano began in 1989-1990 following an 11-month period of heightened seismicity. CO2 emission rates were measured yearly from 1995 to 2013 at Horseshoe Lake (HSL), the largest tree kill area on Mammoth Mountain, and measured intermittently at four smaller degassing areas around Mammoth from 2006 to 2013. The long-term record at HSL shows <span class="hlt">decadal</span>-scale variations in CO2 emissions with two peaks in 2000-2001 and 2011-2012, both of which follow peaks in seismicity by 2-3 years. Between 2000 and 2004 emissions gradually declined during a seismically quiet period, and from 2004 to 2009 were steady at ~ 100 metric tonnes per day (t d- 1). CO2 emissions at the four smaller tree-kill areas also increased by factors of 2-3 between 2006 and 2011-2012, demonstrating a mountain-wide increase in degassing. Delays between the peaks in seismicity and degassing have been <span class="hlt">observed</span> at other volcanic and hydrothermal areas worldwide, and are thought to result from an injection of deep CO2-rich fluid into shallow subsurface reservoirs causing a pressurization event with a delayed transport to the surface. Such processes are consistent with previous studies at Mammoth, and here we highlight (1) the mountain-wide response, (2) the characteristic delay of 2-3 years, and (3) the roughly <span class="hlt">decadal</span> reoccurrence interval for such behavior. Our best estimate of total CO2 degassing from Mammoth Mountain was 416 t d- 1 in 2011 during the peak of emissions, over half of which was emitted from HSL. The cumulative release of CO2 between 1995 and 2013 from diffuse emissions is estimated to be ~ 2-3 Mt, and extrapolation back to 1989 gives ~ 4.8 Mt. This amount of CO2 release is similar to that produced by the mid-sized (VEI 3) 2009 eruption of Redoubt Volcano in Alaska (~ 2.3 Mt over 11 months), and significantly lower than long-term emissions from hydrothermal areas such as Solfatara in Campi Flegrei, Italy (16 Mt over 28 years).</p> <div class="credits"> <p class="dwt_author">Werner, Cynthia; Bergfeld, Deborah; Farrar, Christopher D.; Doukas, Michael P.; Kelly, Peter J.; Kern, Christoph</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">300</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19900033471&hterms=Barometers&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DBarometers"> <span id="translatedtitle">Seasonal <span class="hlt">variability</span> in global sea level <span class="hlt">observed</span> with Geosat altimetry</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Time changes in global mesoscale sea level variances were <span class="hlt">observed</span> with satellite altimetry between November 1986 and March 1988, showing significant, geographically coherent seasonal patterns. The NE Pacific and NE Atlantic variances show the most reliable patterns, higher than their yearly averages in both the fall and winter. The response to wind forcing appears as the major contributor to the NE Pacific and Atlantic signals; errors in the estimated inverse barometer response due to errors in atmospheric pressure, residual orbit errors, and errors in sea state bias are evaluated and found to be negligible contributors to this particular signal. The equatorial regions also show significant seasonal patterns, but the uncertainties in the wet tropospheric correction prevent definitive conclusions. The western boundary current changes are very large but not statistically significant. Estimates of the regression coefficient between sea level and significant wave height, an estimate of the sea state bias correction, range between 2.3 and 2.9 percent and vary with the type of orbit correction applied.</p> <div class="credits"> <p class="dwt_author">Zlotnicki, V.; Fu, L.-L.; Patzert, W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1989-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_14");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" 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onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a style="font-weight: bold;">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_17");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">301</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFMGC53B1057T"> <span id="translatedtitle">Two <span class="hlt">Decades</span> of <span class="hlt">Variability</span> in Nutrient Budgets for Ice-Covered, Closed Basin Lakes in the McMurdo Dry Valleys, Antarctica</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The McMurdo Dry Valleys (MCM) of Antarctica represent one of the world's driest deserts. A collection of permanently ice-covered lakes in the MCM provide an important refuge for microorganisms. Thus, it is of interest to understand the nutrient dynamics of these lakes and how these dynamics have changed over time. One to two <span class="hlt">decade</span>-long records of physical, chemical, and biological characteristics in the East Lobe of Lake Bonney (ELB), Lake Fryxell (FRX), and Lake Hoare (HOR) allowed for development of annual nutrient budgets and analysis of possible causes of <span class="hlt">variability</span>. Annual nutrient budgets were built by accounting for total seasonal streamflow and average seasonal nutrient concentration in streamflow, as well as nutrient diffusion across the chemocline, which roughly coincides with the bottom of the photic zone. Unaccounted-for changes in nutrient content were assumed to be caused by processes internal to the lake. Changes to the proportion of lake volume in the photic zone, seasonal streamflow, and biological activity, represented by chlorophyll-a (CHL) concentration, were considered as potential explanations. For all three lakes, nutrient diffusion either into or out of the photic zone was minimal compared to nutrient inputs from streamflow. The sole exception to this was NH4 inputs to FRX; for eight of the nine years considered, diffusive inputs of NH4 to the photic zone were greater than streamflow inputs. In most cases, internal processes appeared to dominate over streamflow inputs; this is likely because seasonal streamflow represented less than 8% of the photic zone volume in all three lakes. Three exceptions to this trend were the phosphorus budget in ELB, and the NH4 and NO3 budgets in HOR; in these cases, streamflow inputs represented a notable portion of the annual nutrient budgets. The MCM lakes decreased in volume from the early 1990s to the early 2000s; they have since been increasing in volume. The volume of the photic zone was positively correlated to the mean concentrations of NH4 and NO3 in ELB, and to the mean NO2 concentration in FRX. Mean CHL concentration in the photic zone was positively correlated to mean NO2 concentration in ELB; mean CHL concentration in the photic zone was negatively correlated to mean NO2 concentration in HOR. These results suggest that internal nutrient cycling processes dominate the nutrient dynamics of the MCM lakes. To further explore inputs from biological processes, the potential for diffusion from benthic microbial mats in shallow waters could be considered.</p> <div class="credits"> <p class="dwt_author">Truhlar, A. M.; Gooseff, M. N.; McKnight, D. M.; Priscu, J. C.; Doran, P. T.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">302</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://svs.gsfc.nasa.gov/vis/a000000/a002400/a002497/index.html"> <span id="translatedtitle"><span class="hlt">Decadal</span> Comparison of Plankton Levels</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://nsdl.org/nsdl_dds/services/ddsws1-1/service_explorer.jsp">NSDL National Science Digital Library</a></p> <p class="result-summary">The global ocean chlorophyll archive produced by the CZCS was revised using compatible algorithms with SeaWiFS. Both archives were then blended with in situ data to reduce residual errors. This methodology permitted a quantitative comparison of <span class="hlt">decadal</span> changes in global ocean chlorophyll from the CZCS (1979 - 1986) and SeaWiFS (1997 - 2000) records. Global spatial distributions and seasonal variablility of ocean chlorophyll were similar, but global means decreased over the two <span class="hlt">observational</span> segments. Major changes were <span class="hlt">observed</span> regionally: chlorophyll concentrations decreased in the northern high latitudes while chlorophyll in the low latitudes increased. Mid-ocean gyres exhibited limited changes. The overall spatial and seasonal similarity of the two data records suggests that the changes are due to natural <span class="hlt">variability</span>. These results provide evidence of how the Earths climate may be changing and how ocean biota respond.</p> <div class="credits"> <p class="dwt_author">Joycelyn Thomson</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-08-08</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">303</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015ClDy...44..475Y"> <span id="translatedtitle">Modulation of the Pacific <span class="hlt">Decadal</span> Oscillation on the summer precipitation over East China: a comparison of <span class="hlt">observations</span> to 600-years control run of Bergen Climate Model</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Observations</span> show that the summer precipitation over East China often goes through <span class="hlt">decadal</span> variations of opposite sign over North China and the Yangtze River valley (YRV), such as the "southern flood and northern drought" pattern that occurred during the late 1970s-1990s. In this study it is shown that a modulation of the Pacific <span class="hlt">Decadal</span> Oscillation (PDO) on the summer precipitation pattern over East China during the last century is partly responsible for this characteristic precipitation pattern. During positive PDO phases, the warm winter sea surface temperatures (SSTs) in the eastern subtropical Pacific along the western coast of North American propagate to the tropics in the following summer due to weakened oceanic meridional circulation and the existence of a coupled wind-evaporation-SST feedback mechanism, resulting in a warming in the eastern tropical Pacific Ocean (5°N-20°N, 160°W-120°W) in summer. This in turn causes a zonal anomalous circulation over the subtropical-tropical Pacific Ocean that induces a strengthened western Pacific subtropical high (WPSH) and thus more moisture over the YRV region. The end result of these events is that the summer precipitation is increased over the YRV region while it is decreased over North China. The suggested mechanism is found both in the <span class="hlt">observations</span> and in a 600-years fully coupled pre-industrial multi-century control simulations with Bergen Climate Model. The intensification of the WPSH due to the warming in the eastern tropical Pacific Ocean was also examined in idealized SSTA-forced AGCM experiments.</p> <div class="credits"> <p class="dwt_author">Yu, Lei; Furevik, Tore; Otterå, Odd Helge; Gao, Yongqi</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">304</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ClDy...43..447D"> <span id="translatedtitle">A new atmospheric proxy for sea level <span class="hlt">variability</span> in the southeastern North Sea: <span class="hlt">observations</span> and future ensemble projections</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Atmosphere-ocean interactions are known to dominate seasonal to <span class="hlt">decadal</span> sea level <span class="hlt">variability</span> in the southeastern North Sea. In this study an atmospheric proxy for the <span class="hlt">observed</span> sea level <span class="hlt">variability</span> in the German Bight is introduced. Monthly mean sea level (MSL) time series from 13 tide gauges located in the German Bight and one virtual station record are evaluated in comparison to sea level pressure fields over the North Atlantic and Europe. A quasi-linear relationship between MSL in the German Bight and sea level pressure over Scandinavia and the Iberian Peninsula is found. This relationship is used (1) to evaluate the atmospheric contribution to MSL <span class="hlt">variability</span> in hindcast experiments over the period from 1871-2008 with data from the twentieth century reanalysis v2 (20CRv2), (2) to isolate the high frequency meteorological <span class="hlt">variability</span> of MSL from longer-term changes, (3) to derive ensemble projections of the atmospheric contribution to MSL until 2100 with eight different coupled global atmosphere-ocean models (AOGCM's) under the A1B emission scenario and (4) two additional projections for one AOGCM (ECHAM5/MPI-OM) under the B1 and A2 emission scenarios. The hindcast produces a reasonable good reconstruction explaining approximately 80 % of the <span class="hlt">observed</span> MSL <span class="hlt">variability</span> over the period from 1871 to 2008. <span class="hlt">Observational</span> features such as the divergent seasonal trend development in the second half of the twentieth century, i.e. larger trends from January to March compared to the rest of the year, and regional variations along the German North Sea coastline in trends and <span class="hlt">variability</span> are well described. For the period from 1961 to 1990 the Kolmogorov-Smirnow test is used to evaluate the ability of the eight AOGCMs to reproduce the <span class="hlt">observed</span> statistical properties of MSL variations. All models are able to reproduce the statistical distribution of atmospheric MSL. For the target year 2100 the models point to a slight increase in the atmospheric component of MSL with generally larger changes during winter months (October-March). Largest MSL changes in the order of ~5-6 cm are found for the high emission scenario A2, whereas the moderate B1 and intermediate A1B scenarios lead to moderate changes in the order of ~3 cm. All models point to an increasing atmospheric contribution to MSL in the German Bight, but the uncertainties are considerable, i.e. model and scenario uncertainties are in the same order of magnitude.</p> <div class="credits"> <p class="dwt_author">Dangendorf, Sönke; Wahl, Thomas; Nilson, Enno; Klein, Birgit; Jensen, Jürgen</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-07-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">305</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.cawcr.gov.au/staff/sbp/journal_articles/holger_jclim_2005.pdf"> <span id="translatedtitle">Rainfall <span class="hlt">Variability</span> at <span class="hlt">Decadal</span> and Longer Time Scales: Signal or Noise? HOLGER MEINKE,* PETER DEVOIL,* GRAEME L. HAMMER,*, SCOTT POWER,# ROBERT ALLAN,@</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">POTGIETER* *Department of Primary Industries and Fisheries, Toowoomba, Australia School of Land and Food Africa, and western Europe. While low-frequency (LF) signals at a <span class="hlt">decadal</span> frequency are dom- inant gains and long-term sustainability. In this context Basher (2000), Hammer (2000), Hansen (2002</p> <div class="credits"> <p class="dwt_author">Power, Scott</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">306</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013JGRD..118.3369T"> <span id="translatedtitle"><span class="hlt">Decadal</span> time series of tropospheric abundance of N2O isotopomers and isotopologues in the Northern Hemisphere obtained by the long-term <span class="hlt">observation</span> at Hateruma Island, Japan</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary"><span class="hlt">Decadal</span> time series and short-term temporal variations in mixing ratio of atmospheric nitrous oxide (N2O) and abundance of its isotopomers (14N15N16O and 15N14N16O) and isotopologue (14N14N18O) relative to 14N14N16O have been <span class="hlt">observed</span> for the first time in the Northern Hemisphere at Hateruma Island (HAT), Japan during 1999-2010 by monthly air sampling. Results show that the bulk nitrogen isotope ratio ?15Nbulk decreased at the rate of -0.023 ± 0.006‰ yr-1, although the N2O mixing ratio increased at the rate of about 0.7 nmol mol-1 yr-1 (ppb yr-1) during the period. Isotope budget calculation with the ?15Nbulk trend supports the earlier estimates showing that the isotopically light sources such as agriculture and industry contribute to the increase of atmospheric N2O. However, the rate of decrease of ?15Nbulk is slightly smaller in magnitude than the rates obtained virtually for the 20th century from firn air in polar regions and surface air in the Southern Hemisphere (Tasmania and Antarctica), which suggests greater contribution of 15 N-enriched N2O sources in recent years or in the extra-polar Northern Hemisphere. In contrast, the oxygen isotope ratio (?18O) and intramolecular 15N site preference (SP, difference between isotope ratios at central and terminal nitrogen atoms) of N2O showed no significant trends, contrary to previous reports. Results show that no significant seasonal variation exists in ?15Nbulk, ?18O, and SP of N2O at HAT in the past <span class="hlt">decade</span> within the limits of our sampling frequency and analytical precision.</p> <div class="credits"> <p class="dwt_author">Toyoda, Sake; Kuroki, Natsuko; Yoshida, Naohiro; Ishijima, Kentaro; Tohjima, Yasunori; Machida, Toshinobu</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">307</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110007974&hterms=trend+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2522trend%2Banalysis%2522"> <span id="translatedtitle">Seasonal to <span class="hlt">Decadal</span> Variations of Water Vapor in the Tropical Lower Stratosphere <span class="hlt">Observed</span> with Balloon-Borne Cryogenic Frost Point Hygrometers</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We investigated water vapor variations in the tropical lower stratosphere on seasonal, quasi-biennial oscillation (QBO), and <span class="hlt">decadal</span> time scales using balloon-borne cryogenic frost point hygrometer data taken between 1993 and 2009 during various campaigns including the Central Equatorial Pacific Experiment (March 1993), campaigns once or twice annually during the Soundings of Ozone and Water in the Equatorial Region (SOWER) project in the eastern Pacific (1998-2003) and in the western Pacific and Southeast Asia (2001-2009), and the Ticosonde campaigns and regular sounding at Costa Rica (2005-2009). Quasi-regular sounding data taken at Costa Rica clearly show the tape recorder signal. The <span class="hlt">observed</span> ascent rates agree well with the ones from the Halogen Occultation Experiment (HALOE) satellite sensor. Average profiles from the recent five SOWER campaigns in the equatorial western, Pacific in northern winter and from the three Ticosonde campaigns at Costa Rica (10degN) in northern summer clearly show two effects of the QBO. One is the vertical displacement of water vapor profiles associated with the QBO meridional circulation anomalies, and the other is the concentration variations associated with the QBO tropopause temperature variations. Time series of cryogenic frost point hygrometer data averaged in a lower stratospheric layer together with HALOE and Aura Microwave Limb Sounder data show the existence of <span class="hlt">decadal</span> variations: The mixing ratios were higher and increasing in the 1990s, lower in the early 2000s, and probably slightly higher again or recovering after 2004. Thus linear trend analysis is not appropriate to investigate the behavior of the tropical lower stratospheric water vapor.</p> <div class="credits"> <p class="dwt_author">Fujiwara, M.; Voemel, H.; Hasebe, F.; Shiotani, M.; Ogino, S.-Y.; Iwasaki, S.; Nishi, N.; Shibata, T.; Shimizu, K.; Nishimoto, E.; ValverdeCanossa, J. M.; Selkirk, H. B.; Oltmans, S. J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">308</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2000PalOc..15..322L"> <span id="translatedtitle">El Niño Southern Oscillation (ENSO) and <span class="hlt">decadal</span>-scale climate <span class="hlt">variability</span> at 10°N in the eastern Pacific from 1893 to 1994: A coral-based reconstruction from Clipperton Atoll</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We have developed a 101 year (1893-1994) subseasonal oxygen (?18O) and carbon (?13C) isotopic time series from Clipperton Atoll in the eastern Pacific using the coral Porites lobata. In agreement with Linsley et al. [1999] we find that seasonal and interannual coral ?18O <span class="hlt">variability</span> at Clipperton results from <span class="hlt">variability</span> in both water temperature and salinity. Three new coral time series demonstrate the reproducibility of a secular coral ?18O trend of -0.35‰ since 1910 but show varying ?13C trends. Strong <span class="hlt">decadal</span>-scale <span class="hlt">variability</span> in the ?18O record appears related to the Pacific <span class="hlt">Decadal</span> Oscillation (PDO) through postulated changes in the strengths of the Equatorial Counter Current and North Equatorial Current. Interannual <span class="hlt">variability</span> in this coral ?18O record is directly related to the El Niño Southern Oscillation (ENSO) and isolation of this frequency band indicates reduced ENSO <span class="hlt">variability</span> in the eastern equatorial Pacific in the period 1925 to ˜1940, in agreement with instrumental and other Pacific coral records.</p> <div class="credits"> <p class="dwt_author">Linsley, Braddock K.; Ren, Lei; Dunbar, Robert B.; Howe, Stephen S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-06-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">309</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.atmos.colostate.edu/ao/ThompsonPapers/FyfeGillettThompson_GRL2010.pdf"> <span id="translatedtitle">Comparing <span class="hlt">variability</span> and trends in <span class="hlt">observed</span> and modelled globalmean surface temperature</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">land surface temperature and sea surface temperature (SST) datasets [Brohan et al., 2006Comparing <span class="hlt">variability</span> and trends in <span class="hlt">observed</span> and modelled globalmean surface temperature John C; accepted 6 July 2010; published 19 August 2010. [1] The <span class="hlt">observed</span> evolution of the globalmean surface</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">310</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.B53C0476C"> <span id="translatedtitle">Constraining land carbon cycle process understanding with <span class="hlt">observations</span> of atmospheric CO2 <span class="hlt">variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We evaluate our understanding of the land biospheric carbon cycle by benchmarking a model and its variants to atmospheric CO2 <span class="hlt">observations</span> and to an atmospheric CO2 inversion. Though the seasonal cycle in CO2 <span class="hlt">observations</span> is well simulated by the model (RMSE/standard deviation of <span class="hlt">observations</span> <0.5 at most sites north of 15N and <1 for Southern Hemisphere sites) different model setups suggest that the CO2 seasonal cycle provides some constraint on gross photosynthesis, respiration, and fire fluxes revealed in the amplitude and phase at northern latitude sites. CarbonTracker inversions (CT) and model show similar phasing of the seasonal fluxes but agreement in the amplitude varies by region. We also evaluate interannual <span class="hlt">variability</span> (IAV) in the measured atmospheric CO2 which, in contrast to the seasonal cycle, is not well represented by the model. We estimate the contributions of biospheric and fire fluxes, and atmospheric transport <span class="hlt">variability</span> to explaining <span class="hlt">observed</span> <span class="hlt">variability</span> in measured CO2. Comparisons with CT show that modeled IAV has some correspondence to the inversion results >40N though fluxes match poorly at regional to continental scales. Regional and global fire emissions are strongly correlated with <span class="hlt">variability</span> <span class="hlt">observed</span> at northern flask sample sites and in the global atmospheric CO2 growth rate though in the latter case fire emissions anomalies are not large enough to account fully for the <span class="hlt">observed</span> <span class="hlt">variability</span>. We discuss remaining unexplained <span class="hlt">variability</span> in CO2 <span class="hlt">observations</span> in terms of the representation of fluxes by the model. This work also demonstrates the limitations of the current network of CO2 <span class="hlt">observations</span> and the potential of new denser surface measurements and space based column measurements for constraining carbon cycle processes in models.</p> <div class="credits"> <p class="dwt_author">Collatz, G. J.; Kawa, S. R.; Liu, Y.; Zeng, F.; Ivanoff, A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">311</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/astro-ph/0701206v1"> <span id="translatedtitle">X-ray and optical <span class="hlt">variability</span> of Seyfert 1 galaxies as <span class="hlt">observed</span> with XMM-Newton</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">We have examined simultaneous X-ray and optical light curves of a sample of eight nearby Seyfert 1 galaxies <span class="hlt">observed</span> using the EPIC X-ray cameras and Optical Monitor on board XMM. The <span class="hlt">observations</span> span ~1 day and revealed optical <span class="hlt">variability</span> in four of the eight objects studied. In all cases, the X-ray <span class="hlt">variability</span> amplitude exceeded that of the optical both in fractional and absolute luminosity terms. No clearly significant correlations were detected between wavebands using cross correlation analysis. We conclude that, in three of the four objects in which optical <span class="hlt">variability</span> was detected, reprocessing mechanisms between wavebands do not dominate either the optical or X-ray <span class="hlt">variability</span> on the time-scales probed.</p> <div class="credits"> <p class="dwt_author">R. Smith; S. Vaughan</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-01-08</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">312</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/47738673"> <span id="translatedtitle">The Nature and Origin of <span class="hlt">Decadal</span> to Millennial Scale Climate <span class="hlt">Variability</span> in the Southern Tropics of South America: The Holocene Record of Lago Umayo, Peru</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">This paper serves two purposes: to review current ideas about the nature and forcing of <span class="hlt">decadal</span> to millennial scale precipitation\\u000a variation in the southern tropics of South America during the late Quaternary and to present a new methodology for the reconstruction\\u000a of precipitation as applied to a Holocene stable isotopic record of carbonate sediments in a tropical Andean lake, Lago</p> <div class="credits"> <p class="dwt_author">Paul A. Baker; Sherilyn C. Fritz; Stephen J. Burns; Erik Ekdahl; Catherine A. Rigsby</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">313</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.uncw.edu/cmsr/aquaticecology/Laboratory/Reports%20and%20Publications/Burkholder%20et%20al%20LO%202006.pdf"> <span id="translatedtitle">Comprehensive trend analysis of nutrients and related <span class="hlt">variables</span> in a large eutrophic estuary: A <span class="hlt">decadal</span> study of anthropogenic and climatic influences</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">We used a <span class="hlt">decadal</span> data set, with weekly to biweekly sampling in April-October and monthly sampling in November- March, to characterize climatic (hurricane-level storms, a sustained 3-yr drought) and anthropogenic influences on N and P concentrations and loadings to a large eutrophic, poorly flushed estuary, the Neuse Estuary of the Albemarle-Pamlico Estuarine System. Mass volume transport data were obtained with</p> <div class="credits"> <p class="dwt_author">JoAnn M. Burkholder; David A. Dickey; Carol A. Kinder; Robert E. Reed; Michael A. Mallin; Matthew R. McIver; Lawrence B. Cahoon; Greg Melia; Cavell Brownie; Joy Smith</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">314</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20080032403&hterms=behavior+observation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dbehavior%2Bobservation"> <span id="translatedtitle">Cassini UVIS <span class="hlt">Observations</span> of the Io Plasma Torus. 3; <span class="hlt">Observations</span> of Temporal and Azimuthal <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">In this third paper in a series presenting <span class="hlt">observations</span> by the Cassini Ultraviolet Imaging Spectrometer (UVIS) of the Io plasma torus, we show remarkable, though subtle, spatio-temporal variations in torus properties. The Io torus is found to exhibit significant, near sinusoidal variations in ion composition as a functions of azimuthal position. The azimuthal variation in composition is such that the mixing ratio of S II us strongly correlated with the mixing ratio of S III and the equatorial electron density and strongly anti-correlated with the mixing ratios of both S IV and O II and the equatorial electron temperature. Surprisingly, the azimuthal variation in ion composition is <span class="hlt">observed</span> to have a period of 10.07 h -- 1.5% longer than the System III rotation period of Jupiter, yet 1.3% shorter than the System UV period defined by [Brown, M. E., 1995. J. Geophys. Res. 100, 21683-21696]. Although the amplitude of the azimuthal variation of S III and O II remained in the range of 2-5%, the amplitude of the S II and S IV compositional variation ranged between 5 and 25% during the UVIS <span class="hlt">observations</span>. Furthermore, the amplitude of the azimuthal variations of S II and S IV appears to be modulated by its location in System III longitude, such that when the region of maximum S II mixing ration (minimum S IV mixing ratio) is aligned with a System III longitude of 200 deg +/-, the amplitude is a factor of 4 greater than when the variation is anti-aligned. This behavior can explain numerous, often apparently contradictory, <span class="hlt">observations</span> of variations in the properties of the Io plasma torus with the System III and System IV coordinate systems.</p> <div class="credits"> <p class="dwt_author">Steffl, A. J.; Delamere, P. A.; Bagenal, F.</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">315</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012JCHyd.140..107R"> <span id="translatedtitle">The legacy of chlorinated solvents in the Birmingham aquifer, UK: <span class="hlt">Observations</span> spanning three <span class="hlt">decades</span> and the challenge of future urban groundwater development</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Licensed abstraction well data collected during 1986-2008 from a total of 77 wells mainly located at industrial sites combined with historic land use data from 1975 has allowed insight into the legacy of chlorinated solvent contamination in the Birmingham aquifer that underlies the UK's second largest city. This legacy, expected to be reasonably symptomatic of those occurring in other urban aquifers, was characterised by: dominance of parent solvents, particularly TCE (trichloroethene) that widely exceeded drinking-water quality criteria; greater TCE occurrence in wells in proximity to increased historic land use by the metal/engineering solvent-user industry (the relationship providing a first-pass indicator of future resource development potential); regional groundwater vulnerability controls; well abstraction changes (over months to <span class="hlt">decades</span>) influential of <span class="hlt">observed</span> concentration transients and anticipated plume capture or release; persistence of contamination over <span class="hlt">decades</span> (with less soluble PCE (perchloroethene) showing increased persistence relative to TCE) that was reasonably ascribed to slow contaminant release from DNAPL (dense non-aqueous phase liquid) sources and, or low permeability layers; presence of dechlorination products arising from solvent (bio)degradation, although this key attenuation process appeared to have moderate to weak influence regionally on plumes; and, inadvertent, but significant solvent mass removal from the aquifer by industrial abstractions. Key challenges to realising future urban groundwater development were identified based on the <span class="hlt">observed</span> legacy and well capture zone simulations. Despite the extensive contamination of the aquifer, it should still be possible to develop wells of high (several megalitres per day) capacity for drinking water supply (or other lower grade uses) without the requirement for solvent treatment. In those areas with higher risk of contamination, our dataset, together with application of emergent risk assessment approaches (that our dataset may serve to validate), could be used to inform potential abstractors as to whether solvent treatment is likely to be required at a particular abstraction site with time. Challenges identified that were relevant to the future development of Birmingham and urban aquifers more generally include the adequacy of groundwater quality monitoring data and uncertainties in contaminant source terms, abstraction well capture zone predictions and plume natural attenuation, in particular degradation rates. The study endorses that despite significant solvent contamination encountered, strategies can, and need, to be increasingly found to reclaim urban aquifer resources and more sustainably meet urban water demands.</p> <div class="credits"> <p class="dwt_author">Rivett, Michael O.; Turner, Ryan J.; Glibbery (née Murcott), Penny; Cuthbert, Mark O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-10-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">316</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/10404526"> <span id="translatedtitle">Bone marrow content measured in radioimmune bone marrow scintigraphy: intra- and inter-<span class="hlt">observer</span> <span class="hlt">variability</span>.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">The aim of this study was to assess the possible quantification of vertebral residual bone marrow content relative to the bone marrow content of a non-irradiated vertebra. This method is based on the vertebral count activity, measured using radioimmune bone marrow scintigraphy. First, however, we had to evaluate intra- and inter-<span class="hlt">observer</span> <span class="hlt">variability</span>. In three patients who underwent radioimmune bone marrow scintigraphy, two independent <span class="hlt">observers</span> measured the count density in 51 (15 lumbar and 36 thoracic) vertebrae using a manually drawn region of interest. To evaluate intra- and inter-<span class="hlt">observer</span> <span class="hlt">variability</span>, we calculated the means and standard deviations of the differences between measurements. Bland-Altman plots were drawn for all vertebrae as well as for three subgroups of vertebrae (the upper thoracic spine, D1-D6; the lower thoracic spine, D7-D12; and the lumber spine, L1-L5). For all vertebrae, the mean (+/- S.D.) difference, expressed as a percentage of the overall mean, was -0.44 +/- 3.3% for <span class="hlt">observer</span> 1 and -0.3 +/- 2.1% for <span class="hlt">observer</span> 2 for intra-<span class="hlt">observer</span> <span class="hlt">variability</span>; inter-<span class="hlt">observer</span> <span class="hlt">variability</span> varied from 0.55 +/- 3.9% to 1.28 +/- 3.7%. On the Bland-Altman plots, the data points were evenly distributed above and below the 0-line and the linear regression equations matched the line of equality almost perfectly. This pattern was <span class="hlt">observed</span> for all the vertebrae as well as for the subgroups of vertebrae. In conclusion, our results show that the intra- and inter-<span class="hlt">observer</span> <span class="hlt">variabilities</span> are not great, confirming that this technique is simple and robust and can be used for further quantification of bone marrow content in the axial skeleton. PMID:10404526</p> <div class="credits"> <p class="dwt_author">Roland, J; Brans, B; Vervaet, A; Goor, C; Servais, J; de Meyere, P; van den Wijngaert, D; Vandevivere, J; Scalliet, P</p> <p class="dwt_publisher"></p> <p class="publishDate">1999-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">317</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014PASJ...66..115O"> <span id="translatedtitle">Application of the time-delay integration method: Survey <span class="hlt">observations</span> of geosynchronous orbit objects and short-term <span class="hlt">variability</span> <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">"Time-Delay Integration (TDI)" readout technique has been adopted to a mosaic CCD camera equipped with four fully-depleted CCDs. Optical distortion and image deformation due to the TDI operation are discussed. The manner and advantages of the TDI method in survey <span class="hlt">observations</span> of geosynchronous orbit objects are summarized. We propose a new TDI application method of getting short-term light curves of artificial space objects. This method of detecting a short-term <span class="hlt">variability</span> can be applied for a variety of objects, ranging from satellites to stars. It can also be used for the light-curve <span class="hlt">observations</span> of transient objects which might show short-term <span class="hlt">variability</span> and of which the precise time information is needed.</p> <div class="credits"> <p class="dwt_author">Okumura, Shin-ichiro; Yanagisawa, Toshifumi; Nakaya, Hidehiko; Tanaka, Wataru; Nishiyama, Kota; Takahashi, Noritsugu; Yoshikawa, Makoto</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">318</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013ApJ...773...85E"> <span id="translatedtitle">The <span class="hlt">Variable</span> Optical Polarization and Fermi <span class="hlt">Observations</span> of PMN J0948+0022</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We report on <span class="hlt">observations</span> of the ?-ray and optical photopolarimetric behavior of the radio-loud, narrow-line type-1 Seyfert galaxy PMN J0948+0022 over a 27 month period. As this object has recently been suggested to represent a prototype of an emerging class of blazar-like objects, the <span class="hlt">observed</span> properties are compared to those of blazars. We extract doubling timescales of roughly 4 hr for the optical and ?-ray bands. The rapid microvariability in the optical/near-IR, significant and <span class="hlt">variable</span> optical polarization, and strong yet rapidly <span class="hlt">variable</span> ?-ray emission we <span class="hlt">observe</span> for PMN J0948+0022 are all classical <span class="hlt">observational</span> characteristics associated with blazars. However, since these <span class="hlt">observations</span> do not show a clear correlation between the ?-ray and optical behavior, they do not offer conclusive proof that the emissive behavior of PMN J0948+0022 is due to a relativistic jet oriented close to our line of sight.</p> <div class="credits"> <p class="dwt_author">Eggen, Joseph R.; Miller, H. Richard; Maune, Jeremy D.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">319</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1518541"> <span id="translatedtitle">The anatomy of decision support during inpatient care provider order entry (CPOE): Empirical <span class="hlt">observations</span> from a <span class="hlt">decade</span> of CPOE experience at Vanderbilt</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">The authors describe a pragmatic approach to the introduction of clinical decision support at the point of care, based on a <span class="hlt">decade</span> of experience in developing and evolving Vanderbilt’s inpatient “WizOrder” care provider order entry (CPOE) system. The inpatient care setting provides a unique opportunity to interject CPOE-based decision support features that restructure clinical workflows, deliver focused relevant educational materials, and influence how care is delivered to patients. From their empirical <span class="hlt">observations</span>, the authors have developed a generic model for decision support within inpatient CPOE systems. They believe that the model’s utility extends beyond Vanderbilt, because it is based on characteristics of end-user workflows and on decision support considerations that are common to a variety of inpatient settings and CPOE systems. The specific approach to implementing a given clinical decision support feature within a CPOE system should involve evaluation along three axes: what type of intervention to create (for which the authors describe 4 general categories); when to introduce the intervention into the user’s workflow (for which the authors present 7 categories), and how disruptive, during use of the system, the intervention might be to end-users’ workflows (for which the authors describe 6 categories). Framing decision support in this manner may help both developers and clinical end-users plan future alterations to their systems when needs for new decision support features arise. PMID:16290243</p> <div class="credits"> <p class="dwt_author">Miller, Randolph A.; Waitman, Lemuel R.; Chen, Sutin; Rosenbloom, S. Trent</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">320</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20110015263&hterms=sss&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsss"> <span id="translatedtitle">Sea Surface Salinity <span class="hlt">Variability</span> from Simulations and <span class="hlt">Observations</span>: Preparing for Aquarius</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Oceanic fresh water transport has been shown to play an important role in the global hydrological cycle. Sea surface salinity (SSS) is representative of the surface fresh water fluxes and the upcoming Aquarius mission scheduled to be launched in December 2010 will provide excellent spatial and temporal SSS coverage to better estimate the net exchange. In most ocean general circulation models, SSS is relaxed to climatology to prevent model drift. While SST remains a well <span class="hlt">observed</span> <span class="hlt">variable</span>, relaxing to SST reduces the range of SSS <span class="hlt">variability</span> in the simulations (Fig.1). The main objective of the present study is to simulate surface tracers using a primitive equation ocean model for multiple forcing data sets to identify and establish a baseline SSS <span class="hlt">variability</span>. The simulated <span class="hlt">variability</span> scales are compared to those from near-surface argo salinity measurements.</p> <div class="credits"> <p class="dwt_author">Jacob, S. Daniel; LeVine, David M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_15");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return 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id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a style="font-weight: bold;">17</a> <a onClick='return showDiv("page_18");' href="#">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_18");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">321</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2000AstL...26..609A"> <span id="translatedtitle">UBV <span class="hlt">Observations</span> of Post-AGB Supergiants and Peculiarities of Their Photometric <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The systematic UBV <span class="hlt">observations</span> of six <span class="hlt">variable</span> post-AGB supergiants in 1991-1999 are presented. Their <span class="hlt">variability</span> is analyzed. The coolest stars V1027 Cyg and V354 Lac exhibit bimodal pulsations with <span class="hlt">variable</span> amplitudes. Apart from pulsations, the hotter stars V887 Her and IRAS 19386+0155 show light variations associated with a stellar wind. A <span class="hlt">variable</span> stellar wind appears to be mainly responsible for the photometric variations in the still hotter stars SAO 163075 and IRAS 20572+4919. Distinct trends in the yearly mean brightness have been found in three of the six supergiants studied, with the trend amplitude being independent of the spectral range. They are interpreted as the result of dust envelopes composed of large grains with R = A_V/E(B-V) > or = 7 becoming optically thin.</p> <div class="credits"> <p class="dwt_author">Arkhipova, V. P.; Ikonnikova, N. P.; Noskova, R. I.; Sokol, G. V.</p> <p class="dwt_publisher"></p> <p class="publishDate">2000-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">322</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AGUFM.A13G0314L"> <span id="translatedtitle">Quality Control and First Insights on the <span class="hlt">Variability</span> of Surface Wind <span class="hlt">Observations</span> for North Eastern North America</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Over the last <span class="hlt">decades</span>, a policy change in energy sources has been fostered in Atlantic Canada. The purpose of this has been to reduce the dependency on energy produced abroad and to propose feasible alternatives with the aim of reducing greenhouse emissions. The region offers a high potential for the development of wind energy facilities and studies within the framework of wind resource assessment are encouraged. Studies of this nature rely on the quality of <span class="hlt">observational</span> data. Henceforth, it is essential to develop procedures that ensure the reliability of <span class="hlt">observations</span> before they are subjected to any subsequent analysis. This work summarizes the Quality Control process applied to an <span class="hlt">observational</span> database of surface wind module and direction in North Eastern North America. The data set consists of 525 stations compiled from three different sources: 344 land sites from Environment Canada (EC; 1940-2009) located in the provinces of Atlantic Canada and Quebec; 40 buoys distributed over the East Coast and the Canadian Great Lakes provided by Fisheries and Oceans Canada (FOC; 1988-2008); and 141 land sites over both Eastern Canada and North Eastern USA provided by the National Center of Atmospheric Research (NCAR; 1975-2010). The process comprises different phases that: 1) unify measurement units and recording times; 2) find accidentally duplicated periods of data within a time series or between different stations; 3) check for physical consistency in the ranges of values; 4) detect time intervals of anomalous low and high <span class="hlt">variability</span>; and 5) look for long term biases in mean and variance. The temporal extension and resolution of the quality controlled database allows to explore the wind <span class="hlt">variability</span> at different temporal scales, from daily to multidecadal. This contribution will present a first assessment of the wind field climatology in the region, including a description of long term trends, analogous of wind circulation regimes and their relationship to large scale circulation.</p> <div class="credits"> <p class="dwt_author">Lucio-Eceiza, E.; González-Rouco, F. J.; Navarro Montesinos, J.; Hidalgo; Jiménez, P.; García-Bustamante, E.; Conte, J.; Casabella, N.; Beltrami, H.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">323</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19760019018&hterms=category&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcategory"> <span id="translatedtitle">X-ray <span class="hlt">observation</span> of 3U 1700-37. [showing three categories of flux <span class="hlt">variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">X-ray <span class="hlt">observations</span> with Copernicus reveal three categories of flux <span class="hlt">variability</span> in 3U 1700-37. High amplitude hourly variations are energy independent in the 3-11 keV range while a change in the low energy absorbing column causes variations in flux level on an orbital time scale. This absorption is most severe prior to eclipse ingress, suggesting that the distribution of absorbing material around the X-ray source is asymmetrical with respect to the line of centers of the binary system. The absorbing material may be identical with a high density region inferred from optical <span class="hlt">observations</span> of HD 153919. In the third category, the maximum source intensity per binary cycle is <span class="hlt">variable</span> by at least a factor of two between <span class="hlt">observations</span>. Measurement of the eclipse duration on three occasions indicate that it is significantly less than when <span class="hlt">observed</span> by Uhuru.</p> <div class="credits"> <p class="dwt_author">Mason, K. O.; Branduardi, G.; Sanford, P. W.</p> <p class="dwt_publisher"></p> <p class="publishDate">1976-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">324</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AGUFMIN11B1078P"> <span id="translatedtitle">An <span class="hlt">Observational</span> and Computational <span class="hlt">Variable</span> Tagging System for Climate Change Informatics</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">As climate change science uses diverse data from <span class="hlt">observations</span> and computational results to model and validate earth systems from global to local scale, understand complex processes, and perform integrated assessments, adaptable and accessible information systems that integrate these <span class="hlt">observations</span> and model results are required. The data processing tasks associated with the simultaneous use of <span class="hlt">observation</span> and modeling data are time-consuming because scientists are typically familiar with one or the other, but rarely both. Each data domain has its own portal, its own metadata formats, and its own query-building methods for obtaining datasets. The exact definition of <span class="hlt">variables</span> and <span class="hlt">observational</span> parameters may require substantial searches for unfamiliar topics. The dearth of formal descriptions such as ontologies compounds the problem and negatively impacts the advancement of science for each aspect of studying climate change. Our <span class="hlt">Observational</span> and Computational <span class="hlt">Variable</span> Tagging System aims to address these challenges through facilitating the quick identification of datasets of interest across archives by associating <span class="hlt">variables</span> with tags or keywords from a controlled vocabulary. The prototype currently offers the ability to search by tags, <span class="hlt">variable</span> names, and annotations. Names, plain text descriptions, units, dimensions, and a link to each dataset are returned. The information is aggregated from various locations at the source of origin. Keywords from NASA’s Global Change Master Directory provide built-in suggestions for tags. These features ensure accuracy and disambiguation. For the target application, the system tags <span class="hlt">variables</span> and stores data from the Community Climate System Model (CCSM), International Boundary Water Commission, US Geological Survey, National Oceanic and Atmospheric Administration, and NASA. Our tagging system allows users to identify <span class="hlt">variable</span> names and descriptions of <span class="hlt">observational</span> and computational data from a single Web interface. Our system provides an easy-to-use cross-referencing tool to help overcome an important barrier to inter-disciplinary research in climate change science. As proof-of-concept, the tagging system targets a use case based on comparison of model results against <span class="hlt">observational</span> data to validate trends for river stream flows in the forthcoming CCSM4. Existing climate models have no ability to account for damming and other man-made stream flow obstructions. However, <span class="hlt">observational</span> data report on dammed rivers: there is no account of how an un-managed river would fare. One solution to this problem is to use both <span class="hlt">observational</span> data and historical portions of model data to find regions where <span class="hlt">observed</span> stream flow and model results are highly correlated. Based on these regions, an anticipated outcome is model refinement. Another potential outcome is the discovery of un-managed rivers that may be good candidates for correctly predicting stream flow under climate change conditions.</p> <div class="credits"> <p class="dwt_author">Pouchard, L. C.; Lenhardt, W.; Branstetter, M. L.; Runciman, A.; Wang, D.; Kao, S.; King, A. W.; Climate Change Informatics Team</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-12-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">325</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009AIPC.1170..161R"> <span id="translatedtitle">Spectroscopic <span class="hlt">Observations</span> of SRd and RV Tau <span class="hlt">Variables</span> at Middlebury College</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A program to collect time-series spectra of pulsating <span class="hlt">variable</span> stars was undertaken over a period of several months in 2004 with the 0.6-m reflecting telescope at the Middlebury College Observatory using a bench-mounted, fiber-fed CCD spectrograph. The spectra were obtained in the red region (5800-6800 A?) at resolution approximately 2.5 A?. Primarily, stars classified SRd or RV Tau were <span class="hlt">observed</span>, although other targets (such as delta Scu <span class="hlt">variables</span>) were included as well. The spectral coverage and resolution allow, for stars brighter than roughly R = 10, the study of H? emission or absorption strength variation, as well as the determination of temperature spectral class. The spectrograph is also capable of radial velocity determinations (for brighter specimens) at the level of a few km/s. This program demonstrated the utility of a dedicated, modest-aperture telescope in acquisition of useful spectroscopic time-series <span class="hlt">observations</span> for these <span class="hlt">variable</span> stars.</p> <div class="credits"> <p class="dwt_author">Ratcliff, Stephen J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">326</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://eric.ed.gov/?q=latent&pg=5&id=EJ990896"> <span id="translatedtitle">Estimating Latent <span class="hlt">Variable</span> Interactions with Nonnormal <span class="hlt">Observed</span> Data: A Comparison of Four Approaches</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p class="result-summary">A Monte Carlo simulation was conducted to investigate the robustness of 4 latent <span class="hlt">variable</span> interaction modeling approaches (Constrained Product Indicator [CPI], Generalized Appended Product Indicator [GAPI], Unconstrained Product Indicator [UPI], and Latent Moderated Structural Equations [LMS]) under high degrees of nonnormality of the <span class="hlt">observed</span>…</p> <div class="credits"> <p class="dwt_author">Cham, Heining; West, Stephen G.; Ma, Yue; Aiken, Leona S.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">327</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.po.gso.uri.edu/dynamics/KESS/KESS_SSHpaper_v3.1.pdf"> <span id="translatedtitle">Comparisons of sea surface height <span class="hlt">variability</span> <span class="hlt">observed</span> by pressure-recording inverted echo sounders and satellite</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Comparisons of sea surface height <span class="hlt">variability</span> <span class="hlt">observed</span> by pressure-recording inverted echo sounders measurements from an array of 43 pressure-recording in- verted echo sounders (PIESs) in the Kuroshio Extension-recording inverted echo sounder (PIES), satellite al- timetry, Kuroshio Extension, acoustic echo time, ocean bottom</p> <div class="credits"> <p class="dwt_author">Rhode Island, University of</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">328</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015ATel.7236....1S"> <span id="translatedtitle">Near-infrared <span class="hlt">observations</span> of Nova Sco 2015 and the luminous red <span class="hlt">variable</span> in M31</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Near infrared <span class="hlt">observations</span> are reported of Nova Sco 2015 (PNV J17032620-3504140) and the luminous red <span class="hlt">variable</span> in M31 (Nova M31N 2015-01a = MASTER J004207.99+405501.1 ) using the Mount Abu 1.2m telescope and the 1024x1024 HgCdTe NIR camera/spectrograph (NICS).</p> <div class="credits"> <p class="dwt_author">Srivastava, M.; Ashok, N. M.; Banerjee, D. P. K.; Venkataraman, V.</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">329</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.nerc-essc.ac.uk/~rpa/PAPERS/Slingo2008Radagast1.pdf"> <span id="translatedtitle">Overview of <span class="hlt">observations</span> from the RADAGAST experiment in Niamey, Niger: Meteorology and thermodynamic <span class="hlt">variables</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Overview of <span class="hlt">observations</span> from the RADAGAST experiment in Niamey, Niger: Meteorology (RADAGAST) experiment in Niamey, Niger, in 2006. RADAGAST combined data from the ARM Program Mobile Facility in Niamey, Niger: Meteorology and thermodynamic <span class="hlt">variables</span>, J. Geophys. Res., 113, D00E01, doi:10.1029/2008JD</p> <div class="credits"> <p class="dwt_author">Allan, Richard P.</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">330</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.rsmas.miami.edu/assets/pdfs/upper-ocean-dynamics/2008JC005025.pdf"> <span id="translatedtitle">HF radar <span class="hlt">observations</span> of small-scale surface current <span class="hlt">variability</span> in the Straits of Florida</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">HF radar <span class="hlt">observations</span> of small-scale surface current <span class="hlt">variability</span> in the Straits of Florida A. B-frequency Wellen radar (WERA), transmitting at 16.045 MHz, was deployed along the eastern Florida Shelf current measurements within the radar footprint along the shelf break at 86-m depth. The shallowest ADCP</p> <div class="credits"> <p class="dwt_author">Miami, University of</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">331</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/56437165"> <span id="translatedtitle"><span class="hlt">Observing</span> seasonal bottom pressure <span class="hlt">variability</span> in the North Pacific with GRACE</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">Using monthly gravity field solutions from GRACE together with output from an ocean model we assess the ability of GRACE to <span class="hlt">observe</span> seasonal ocean bottom pressure <span class="hlt">variability</span> in the North Pacific. First, the spatial structure and temporal evolution of the long-term mean seasonal bottom pressure cycle in the North Pacific is characterised in the context of the ocean model. It</p> <div class="credits"> <p class="dwt_author">R. J. Bingham; C. W. Hughes</p> <p class="dwt_publisher"></p> <p class="publishDate">2006-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">332</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020068102&hterms=astro&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dastro"> <span id="translatedtitle">Understanding the Long-Term Spectral <span class="hlt">Variability</span> of Cygnus X-1 from BATSE and ASM <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">We present a spectral analysis of <span class="hlt">observations</span> of Cygnus X-1 by the RXTE/ASM (1.5-12 keV) and CGRO/BATSE (20-300 keV), including about 1200 days of simultaneous data. We find a number of correlations between intensities and hardnesses in different energy bands from 1.5 keV to 300 keV. In the hard (low) spectral state, there is a negative correlation between the ASM 1.5-12 keV flux and the hardness at any energy. In the soft (high) spectral state, the ASM flux is positively correlated with the ASM hardness (as previously reported) but uncorrelated with the BATSE hardness. In both spectral states, the BATSE hardness correlates with the flux above 100 keV, while it shows no correlation with the flux in the 20-100 keV range. At the same time, there is clear correlation between the BATSE fluxes below and above 100 keV. In the hard state, most of the <span class="hlt">variability</span> can be explained by softening the overall spectrum with a pivot at approximately 50 keV. The <span class="hlt">observations</span> show that there has to be another, independent <span class="hlt">variability</span> pattern of lower amplitude where the spectral shape does not change when the luminosity changes. In the soft state, the <span class="hlt">variability</span> is mostly caused by a <span class="hlt">variable</span> hard (Comptonized) spectral component of a constant shape superimposed on a constant soft blackbody component. These <span class="hlt">variability</span> patterns are in agreement with the dependence of the rms <span class="hlt">variability</span> on the photon energy in the two states. We interpret the <span class="hlt">observed</span> correlations in terms of theoretical Comptonization models. In the hard state, the <span class="hlt">variability</span> appears to be driven mostly by changing flux in seed photons Comptonized in a hot thermal plasma cloud with an approximately constant power supply. In the soft state, the <span class="hlt">variability</span> is consistent with flares of hybrid, thermal/nonthermal, plasma with <span class="hlt">variable</span> power above a stable cold disk. Also, based on broadband pointed <span class="hlt">observations</span> simultaneous with those of the ASM and BATSE, we find the intrinsic bolometric luminosity increases by a factor of approximately 3-4 from the hard state to the soft one, which supports models of the state transition based on a change of the accretion rate.</p> <div class="credits"> <p class="dwt_author">Zdziarski, Andrzej A.; Poutanen, Juri; Paciesas, William S.; Wen, Linqing; Six, N. Frank (Technical Monitor)</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">333</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010AAN...422....1W"> <span id="translatedtitle"><span class="hlt">Observing</span> Campaign on Hubble's First <span class="hlt">Variable</span> in M31: M31_V1</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">An <span class="hlt">observing</span> campaign is being carried out on M31_V1, the first <span class="hlt">variable</span> star discovered in M31 by Edwin Hubble. The Hubble Heritage Team, with Dr. Keith Noll (STScI) as P.I., plans to <span class="hlt">observe</span> M31_V1 with HST, and needs to know the phase of this Cepheid <span class="hlt">variable</span>. Although basic parameters are known for this star, no recent photometry exists, so <span class="hlt">observations</span> are required to generate current phase information. In 1925 Edwin Hubble published a note in The Observatory (vol. 48, 139) on "Cepheids in Spiral Nebulae." In 1929, he published a seminal paper in the Astrophysical Journal (vol. 69, 103), "A Spiral Nebula as a Stellar System, Messier 31." This paper discussed in detail the galaxy and the 50 <span class="hlt">variable</span> stars he found in its outer regions. Hubble remarked that the 40 Cepheids found showed the period-luminosity relationship in a conspicuous manner, enabling distance to the galaxy to be calculated. Furthermore, he said that the results of his calculations supported the value determined by Harlow Shapley of the zero point of the period-luminosity relation. This confirmation of the zero point had significant implications for future extragalactic distance determinations. As the first of the <span class="hlt">variables</span> on Hubble's list, V1, a Cepheid, is a historical curiosity. M31_V1 is magnitude 19.4V. B-V = +1.28, period is 30.41 days, and amplitude ~ 1.2 magnitudes in B, likely smaller in V. Five nights of data obtained by Arne Henden, AAVSO, show that the <span class="hlt">variable</span> appears to have peaked on 2010 June 19 at about R=18 and as of July 2 was on its way down. It is recommended that <span class="hlt">observers</span> use either an Rc filter or <span class="hlt">observe</span> unfiltered. About an hour or more of exposure per integration will be required to reach S/N = 20, depending on your equipment and sky brightness; multiple exposures and stacking might be necessary to avoid saturating the background. The field is not crowded, and the <span class="hlt">variable</span> itself is not blended. Contamination from the M31 background should n! ot be prohibitive. Finder charts with sequence may be created using the AAVSO <span class="hlt">Variable</span> Star Plotter (http://www.aavso.org/vsp); Rc magnitudes of comparison stars are in the chart-associated photometry table. An R-band finder chart from the Isaac Newton 2.5-m telescope provided by Arne Henden is available. <span class="hlt">Observations</span> should be submitted to the AAVSO International Database. See full Alert Notice for more details and links to images and charts.</p> <div class="credits"> <p class="dwt_author">Waagen, Elizabeth O.</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-07-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">334</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2007AAS...210.1301W"> <span id="translatedtitle"><span class="hlt">Observation</span> Of New <span class="hlt">Variable</span> Stars In The Field Of Open Cluster M23</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">In 2002 a program of surveying regions containing bright open star clusters was initiated using the <span class="hlt">observing</span> facilities at Luther College. As part of this program the half degree square field containing open cluster M23 was <span class="hlt">observed</span> in 2003, 2005 and 2006, resulting in approximately 45,000 2.5-second images, 45,000 3.5-second images and 65,000 5.0-second images. The data set contains images from 94 nights spanning a time range from JD 2452810 to JD 2454005. We have searched for stellar <span class="hlt">variability</span> on timescales from seconds to years in approximately 1600 stars in this field. Unambiguous <span class="hlt">variability</span> is apparent in 30 stars ranging in magnitude from about 10 to 17. Twenty-eight of these stars have not been previously reported as <span class="hlt">variable</span>. Seven of the stars are eclipsing binaries, including two apparent W UMa-type contact binaries and one additional eclipsing binary with a period shorter than 0.6 days. The remaining 23 <span class="hlt">variables</span> are red pulsating stars with long periods. Most of these stars have amplitudes smaller than two magnitudes and periods between 200 and 400 days. Thus, they are likely Semi-Regular <span class="hlt">variables</span>. We present celestial coordinates, estimated amplitude and estimated period for each of these stars, as well as several selected light curves. Finally, we have performed low-precision BVRI photometry of the field and have placed most of the <span class="hlt">observed</span> <span class="hlt">variables</span> on color magnitude diagrams. We are grateful for support from the Roy J. Carver Charitable Trust and the R. J. McElroy Trust.</p> <div class="credits"> <p class="dwt_author">Wilkerson, Jeffrey A.; Brown, T. S.; Frank, K. A.; Joshi, U.; Lacoul, B. K.; Rengstorf, N. P.; Schiefelbein, A. M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2007-05-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">335</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2010SPIE.7622E..0AD"> <span id="translatedtitle">A stepwedge-based method for measuring breast density: <span class="hlt">observer</span> <span class="hlt">variability</span> and comparison with human reading</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Breast density is positively linked to the risk of developing breast cancer. We have developed a semi-automated, stepwedge-based method that has been applied to the mammograms of 1,289 women in the UK breast screening programme to measure breast density by volume and area. 116 images were analysed by three independent operators to assess inter-<span class="hlt">observer</span> <span class="hlt">variability</span>; 24 of these were analysed on 10 separate occasions by the same operator to determine intra-<span class="hlt">observer</span> <span class="hlt">variability</span>. 168 separate images were analysed using the stepwedge method and by two radiologists who independently estimated percentage breast density by area. There was little intra-<span class="hlt">observer</span> <span class="hlt">variability</span> in the stepwedge method (average coefficients of variation 3.49% - 5.73%). There were significant differences in the volumes of glandular tissue obtained by the three operators. This was attributed to variations in the operators' definition of the breast edge. For fatty and dense breasts, there was good correlation between breast density assessed by the stepwedge method and the radiologists. This was also <span class="hlt">observed</span> between radiologists, despite significant inter-<span class="hlt">observer</span> variation. Based on analysis of thresholds used in the stepwedge method, radiologists' definition of a dense pixel is one in which the percentage of glandular tissue is between 10 and 20% of the total thickness of tissue.</p> <div class="credits"> <p class="dwt_author">Diffey, Jenny; Berks, Michael; Hufton, Alan; Chung, Camilla; Verow, Rosanne; Morrison, Joanna; Wilson, Mary; Boggis, Caroline; Morris, Julie; Maxwell, Anthony; Astley, Susan</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">336</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20120000700&hterms=Pereira&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DPereira"> <span id="translatedtitle">Quantifying Spatial and Seasonal <span class="hlt">Variability</span> in Atmospheric Ammonia with In Situ and Space-Based <span class="hlt">Observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Ammonia plays an important role in many biogeochemical processes, yet atmospheric mixing ratios are not well known. Recently, methods have been developed for retrieving NH3 from space-based <span class="hlt">observations</span>, but they have not been compared to in situ measurements. We have conducted a field campaign combining co-located surface measurements and satellite special <span class="hlt">observations</span> from the Tropospheric Emission Spectrometer (TES). Our study includes 25 surface monitoring sites spanning 350 km across eastern North Carolina, a region with large seasonal and spatial <span class="hlt">variability</span> in NH3. From the TES spectra, we retrieve a NH3 representative volume mixing ratio (RVMR), and we restrict our analysis to times when the region of the atmosphere <span class="hlt">observed</span> by TES is representative of the surface measurement. We find that the TES NH3 RVMR qualitatively captures the seasonal and spatial <span class="hlt">variability</span> found in eastern North Carolina. Both surface measurements and TES NH3 show a strong correspondence with the number of livestock facilities within 10 km of the <span class="hlt">observation</span>. Furthermore, we find that TES H3 RVMR captures the month-to-month <span class="hlt">variability</span> present in the surface <span class="hlt">observations</span>. The high correspondence with in situ measurements and vast spatial coverage make TES NH3 RVMR a valuable tool for understanding regional and global NH3 fluxes.</p> <div class="credits"> <p class="dwt_author">Pinder, Robert W.; Walker, John T.; Bash, Jesse O.; Cady-Pereira, Karen E.; Henze, Daven K.; Luo, Mingzhao; Osterman, Gregory B.; Shepard, Mark W.</p> <p class="dwt_publisher"></p> <p class="publishDate">2011-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">337</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=19810050794&hterms=variables+STAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dvariables%2BSTAR"> <span id="translatedtitle">X-ray <span class="hlt">observations</span> of selected cataclysmic <span class="hlt">variable</span> stars using the Einstein Observatory</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">X-ray <span class="hlt">observations</span> of 12 cataclysmic <span class="hlt">variable</span> stars using the Einstein Observatory are reported. Nine of these stars, representing all subclasses of cataclysmic <span class="hlt">variables</span>, were detected. Their fluxes range from 2 x 10 to the -13th to 1 x 10 to the -11th ergs/sq cm-s in the energy interval 0.16-4.5 keV. The spectra of all the sources detected are relatively hard (kT not less than 5 keV). There is no evidence for an ultrasoft emission component (kT of about 50 eV) such as has been <span class="hlt">observed</span> from the dwarf novae SS Cyg and U Gem during optical outburst. The X-ray and optical fluxes of the objects <span class="hlt">observed</span> can be understood in terms of differences in mass accretion rate if the accreting stars in these close binary systems possess a weak magnetic field.</p> <div class="credits"> <p class="dwt_author">Cordova, F. A.; Mason, K. O.; Nelson, J. E.</p> <p class="dwt_publisher"></p> <p class="publishDate">1981-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">338</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2015MNRAS.448.1153P"> <span id="translatedtitle">Spectral <span class="hlt">variability</span> in Swift and Chandra <span class="hlt">observations</span> of the ultraluminous source NGC 55 ULX1</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">NGC 55 ULX1 is a bright Ultraluminous X-ray source located 1.78 Mpc away. We analysed a sample of 20 Swift <span class="hlt">observations</span>, taken between 2013 April and August, and two Chandra <span class="hlt">observations</span> taken in 2001 September and 2004 June. We found only marginal hints of a limited number of dips in the light curve, previously reported to occur in this source, although the uncertainties due to the low counting statistics of the data are large. The Chandra and Swift spectra showed clearly spectral <span class="hlt">variability</span> which resembles those <span class="hlt">observed</span> in other ULXs. We can account for this spectral <span class="hlt">variability</span> in terms of changes in both the normalization and intrinsic column density of a two-component model consisting of a blackbody (for the soft component) and a multicolour accretion disc (for the hard component). We discuss the possibility that strong outflows ejected by the disc are in part responsible for such spectral changes.</p> <div class="credits"> <p class="dwt_author">Pintore, Fabio; Esposito, Paolo; Zampieri, Luca; Motta, Sara; Wolter, Anna</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-04-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">339</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2001rxte.prop60151K"> <span id="translatedtitle">Testing the Blazar Paradigm Through Time <span class="hlt">Variability</span> - <span class="hlt">Observation</span> of `NEW' Intermediate BL Lac 1424+240 -</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We propose to <span class="hlt">observe</span> the intermediate blazar 1424+240 for 400 ksec. Our recent studies reveal that the characteristic X-ray <span class="hlt">variability</span> in blue blazars is much faster than that of red blazars, reflecting the differences in X-ray emission mechanisms. An ideal test of this scenario is to trace the faster synchrotron and the slower inverse- Compton variation at the same time over an extended period. 1424+240 is the most suitable source for this study. ASCA <span class="hlt">observations</span> revealed an unusual concave spectrum with the break at 5 keV, indicating that the highest energy synchrotron radiation and lowest energy inverse Compton radiation are both visible in the RXTE X-ray band. Our <span class="hlt">observation</span> will clarify efforts to unify all blazar classes based on their time <span class="hlt">variability</span>.</p> <div class="credits"> <p class="dwt_author">Kataoka, Jun</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">340</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/1502.03651.pdf"> <span id="translatedtitle">New <span class="hlt">Variable</span> Stars Discovered by the APACHE Survey. II. Results After the Second <span class="hlt">Observing</span> Season</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Routinely operating since July 2012, the APACHE survey has celebrated its second birthday. While the main goal of the Project is the detection of transiting planets around a large sample of bright, nearby M dwarfs in the northern hemisphere, the APACHE large photometric database for hundreds of different fields represents a relevant resource to search for and provide a first characterization of new <span class="hlt">variable</span> stars. We celebrate here the conclusion of the second year of <span class="hlt">observations</span> by reporting the discovery of 14 new <span class="hlt">variables</span>.</p> <div class="credits"> <p class="dwt_author">Damasso, M; Bernagozzi, A; Bertolini, E; Calcidese, P; Carbognani, A; Cenadelli, D; Christille, J M; Giacobbe, P; Lanteri, L; Smart, M G Lattanzi R; Sozzetti, A</p> <p class="dwt_publisher"></p> <p class="publishDate">2015-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_16");' href="#" title="Previous Page"> <img 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href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_19");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">341</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/servlets/purl/263567"> <span id="translatedtitle"><span class="hlt">Observations</span> of regional and local <span class="hlt">variability</span> in the optical properties of maritime clouds</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">White and Fairall (1995) calculated the optical properties of the marine boundary layer (MBL) clouds <span class="hlt">observed</span> during the Atlantic Stratocumulus Transition Experiment (ASTEX) and compared their results with the results obtained by Fairall et al. for the MBL clouds <span class="hlt">observed</span> during the First International Satellite Climatology Program (ISSCP) Regional Experiment (FIRE). They found a factor of two difference in the optical depth versus liquid water relationship that applies to the clouds <span class="hlt">observed</span> in each case. In the present study, we present evidence to support this difference. We also investigate the local <span class="hlt">variability</span> exhibited in the ASTEX optical properties using measurements of the boundary layer aerosol concentration.</p> <div class="credits"> <p class="dwt_author">White, A.B. [Univ. of Colorado at Boulder/National Oceanic and Atmospheric Administration, Boulder, CO (United States); Fairall, C.W. [Environmental Technology Lab., Boulder, CO (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">1996-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">342</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20100031078&hterms=variables+STAR&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvariables%2BSTAR"> <span id="translatedtitle">High Angular Resolution <span class="hlt">Observations</span> of Episodic Dust Emission from Long Period <span class="hlt">Variable</span> Stars Twenty Years of <span class="hlt">Observations</span> with the Berkeley Infrared Spatial Interferometer</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">Over the past twenty years the U. C. Berkeley Infrared Spatial Interferometer has <span class="hlt">observed</span> a number of Long Period <span class="hlt">Variable</span> stars in the mid-infrared, obtaining information on the spatial distribution of dust around these stars with resolutions of the order of a few tens of milliarcseconds. The ISI is a heterodyne interferometer operating mostly at 11.15 microns, initially with two telescopes. In the last <span class="hlt">decade</span>, it has been taking data regularly with three telescopes, thus obtaining visibility data on three baselines and also a closure phase. Over the course of the years, the ISI has been able to measure the physical properties of the dust shells surrounding these stars, in particular the inner radii of the dust shells, as well as the temperature and density distribution. For some stars, the ISI has also made precision measurements of their diameters in the mid-infrared. Closure phase measurements have revealed asymmetries in the dust distributions around many stars. Most surprisingly the ISI data has shown evidence for substantial changes in the amount of dust on time scales of 5-10 years, rather than being directly correlated with the stellar pulsation periods, which are of the order of one year. We discuss past results and new results from the ISI that highlight the dynamic environment around these stars.</p> <div class="credits"> <p class="dwt_author">Danchi, William</p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">343</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2012AGUFMEP13A0817P"> <span id="translatedtitle">Linking Temporal and Spatial <span class="hlt">Variability</span> of Millennial and <span class="hlt">Decadal</span>-Scale Sediment Yield to Aquatic Habitat in the Columbia River Watershed</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Understanding and predicting the mechanisms, rates and timing of sediment production and storage in the landscape are fundamental problems in the watershed sciences. This is of particular concern given that excess sedimentation is considered a major pollutant to aquatic ecosystems. Rates of sediment delivery to stream networks are characteristically unsteady and non-uniform. Because of this, conventional approaches for predicting sediment yield provide incomplete and often inaccurate information. Terrestrial cosmogenic nuclides (TCNs) provide an estimate of spatially averaged rates of sediment yield from 10^1 to 10^4 km2 and temporally integrated from 10^3 to 10^5 years. Here, I am using TCNs to constrain unsteadiness and non-uniformity of sediment yield within specific catchments of the Columbia River Watershed. This is in combination with GIS analysis (e.g. longitudinal profiles, hypsometric curves, geologic mapping) optically stimulated luminescence (OSL), Carbon-14 (C14) dating of fluvial deposits within the modern and abandoned floodplain, <span class="hlt">decadal</span>-scale sediment yield river gauge data and rapid geomorphic assessments based on the Fluvial Audit and River Styles frameworks. These methods are employed to address the following three broad questions. 1) How do long-term rates of sediment supply vary spatially and temporally throughout the Columbia River watershed? 2) How have human activities influenced (amplified or dampened) processes of erosion and sediment transport? 3) At what scales do long-term and near-term erosion rates influence aquatic habitat metrics?</p> <div class="credits"> <p class="dwt_author">Portugal, E. W.; Belmont, P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">344</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AIPC.1553...69M"> <span id="translatedtitle">Towards identification of relevant <span class="hlt">variables</span> in the <span class="hlt">observed</span> aerosol optical depth bias between MODIS and AERONET <span class="hlt">observations</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Measurements made by satellite remote sensing, Moderate Resolution Imaging Spectroradiometer (MODIS), and globally distributed Aerosol Robotic Network (AERONET) are compared. Comparison of the two datasets measurements for aerosol optical depth values show that there are biases between the two data products. In this paper, we present a general framework towards identifying relevant set of <span class="hlt">variables</span> responsible for the <span class="hlt">observed</span> bias. We present a general framework to identify the possible factors influencing the bias, which might be associated with the measurement conditions such as the solar and sensor zenith angles, the solar and sensor azimuth, scattering angles, and surface reflectivity at the various measured wavelengths, etc. Specifically, we performed analysis for remote sensing Aqua-Land data set, and used machine learning technique, neural network in this case, to perform multivariate regression between the ground-truth and the training data sets. Finally, we used mutual information between the <span class="hlt">observed</span> and the predicted values as the measure of similarity to identify the most relevant set of <span class="hlt">variables</span>. The search is brute force method as we have to consider all possible combinations. The computations involves a huge number crunching exercise, and we implemented it by writing a job-parallel program.</p> <div class="credits"> <p class="dwt_author">Malakar, N. K.; Lary, D. J.; Gencaga, D.; Albayrak, A.; Wei, J.</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">345</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2009EGUGA..11.5053B"> <span id="translatedtitle">First detection of a seasonality of stratomesospheric CO above mid-latitudes via solar FTIR measurements. Analysis of one <span class="hlt">decade</span> of <span class="hlt">observations</span> at the NDACC Primary Station Zugspitze</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">Model studies revealed that stratomesospheric CO exhibits considerable seasonal and latitudinal variations caused by the competition between downward transport from the thermospheric production region and photochemical loss processes. A sharp latitudinal gradient with highest abundances at the North Pole was found which implies that the mid-latitude region can exhibit strong enhancements of stratomesospheric CO under conditions of large-scale planetary wave activity displacing CO enriched vortex air from North to South. Unfortunately, until now there are not enough continuous long-term measurements of stratomesospheric CO at mid-latitudes to prove this assumption. Velazco et al. [2007] reported ground-based FTIR measurements of stratomesospheric CO partial columns from several sites in the Arctic, northern and southern mid-latitudes, and Antarctica. Unfortunately, this study concluded that, generally, the mid-latitude stations show no significant annual <span class="hlt">variability</span> of stratomesospheric CO columns. However, already early microwave <span class="hlt">observations</span> indicated that stratomesospheric CO is about twice as large in mid-latitude winter as in summer [Clancy et al., 1982]. Obviously, there was a technical difficulty with the FTIR inversion of mid-latitude mesospheric CO in the early study by Velazco et al. [2007]. It is one aim of this paper to present a solution to this problem. Therefore, this paper describes an improved retrieval approach for ground-based FTIR stations, that is capable to derive a significant seasonal cycle of stratomesospheric CO at mid-latitudes. Coincident measurements at Zugspitze (2964 m a.s.l.) and Garmisch (744 m a.s.l.) show perfect agreement (R = 0.94) which proves that the new retrieval approach is not limited to high altitude stations, and is thus applicable to all mid-latitude stations. The first long-term series of stratomesospheric CO at mid-latitudes (42.42°N, 10.98°E) derived from ground-based FTIR spectrometry is presented (1999 to 2008). Between November and April the monthly mean time series shows column enhancements by a factor of 2.2 relative to the summer minimum of 1.64E16 cm-2 with a maximum of 3.63E16 cm-2 in February and strong year-to-year <span class="hlt">variability</span> of up to 32 % (1 sigma). The seasonality agrees very well with the WACCM model [Garcia et al., 2007] which, however, can not reproduce measured year-to-year <span class="hlt">variability</span>. Pronounced short time enhancements (duration of 1 to 3 days) are <span class="hlt">observed</span>, which during winter exceed the monthly-mean background seasonality by up to 276 %. Comparison with WACCM and FTIR measurements at high-latitudes [Jones et al., 2007] reveal, that these enhancements reflect inner vortex conditions and are due to transport by planetary waves. References Clancy, R. T., D. O. Muhleman and G. L. Berge (1982), Microwave spectra of terrestrial mesospheric CO, J. Geophys. Res., 87, 5009 - 5014. Garcia, R. R., D. R. Marsh, D. E. Kinnison, B. A. Boville, and F. Sassi (2007), Simulation of secular trends in the middle atmosphere, 1950-2003, J. Geophys. Res., 112, D09301, doi: 10.1029/2006JD007485. Jones, N. B., Y. Kasai, E. Dupuy, Y. Murayama, J. Urban, B. Barret, M. Sinnhuber, A. Kagawa, T. Koshiro, P. Ricaud, and D. Murtagh (2007), Stratomesospheric CO measured by a ground-based Fourier Transform Spectrometer over Poker Flat, Alaska: Comparison with Odin/SMR and a 2-D model, J. Geophys. Res., 112, D20303, doi: 10.1029/2006JD007916. Velazco, V., S. W. Wood, M.Sinnhuber, I. Kramer, N. B. Jones, Y. Kasai, J. Notholt, T. Warneke, T. Blumenstock, F. Hase, F. J. Murcray, and O. Schrems (2007), Annual variation of strato-mesospheric carbon monoxide measured by ground-based Fourier transform infrared spectrometry, Atmos. Chem. Phys., 7, 1305-1312.</p> <div class="credits"> <p class="dwt_author">Borsdorff, T.; Sussmann, R.; Rettinger, M.</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-04-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">346</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://ntrs.nasa.gov/search.jsp?R=20020039168&hterms=latest+floods&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlatest%2Bfloods"> <span id="translatedtitle"><span class="hlt">Variability</span> and Predictability of Land-Atmosphere Interactions: <span class="hlt">Observational</span> and Modeling Studies</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p class="result-summary">The overall goal of this project is to increase our understanding of seasonal to interannual <span class="hlt">variability</span> and predictability of atmosphere-land interactions. The project objectives are to: 1. Document the low frequency <span class="hlt">variability</span> in land surface features and associated water and energy cycles from general circulation models (GCMs), <span class="hlt">observations</span> and reanalysis products. 2. Determine what relatively wet and dry years have in common on a region-by-region basis and then examine the physical mechanisms that may account for a significant portion of the <span class="hlt">variability</span>. 3. Develop GCM experiments to examine the hypothesis that better knowledge of the land surface enhances long range predictability. This investigation is aimed at evaluating and predicting seasonal to interannual <span class="hlt">variability</span> for selected regions emphasizing the role of land-atmosphere interactions. Of particular interest are the relationships between large, regional and local scales and how they interact to account for seasonal and interannual <span class="hlt">variability</span>, including extreme events such as droughts and floods. North and South America, including the Global Energy and Water Cycle Experiment Continental International Project (GEWEX GCIP), MacKenzie, and LBA basins, are currently being emphasized. We plan to ultimately generalize and synthesize to other land regions across the globe, especially those pertinent to other GEWEX projects.</p> <div class="credits"> <p class="dwt_author">Roads, John; Oglesby, Robert; Marshall, Susan; Robertson, Franklin R.</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">347</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014JGRC..119.8838H"> <span id="translatedtitle">Moored <span class="hlt">observations</span> of synoptic and seasonal <span class="hlt">variability</span> in the East Greenland Coastal Current</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present a year-round assessment of the hydrographic <span class="hlt">variability</span> within the East Greenland Coastal Current on the Greenland shelf from five synoptic crossings and 4 years of moored hydrographic data. From the five synoptic sections the current is <span class="hlt">observed</span> as a robust, surface intensified flow with a total volume transport of 0.66 ± 0.18 Sv and a freshwater transport of 42 ± 12 mSv. The moorings showed heretofore unobserved <span class="hlt">variability</span> in the abundance of Polar and Atlantic water masses in the current on synoptic scales. This is exhibited as large vertical displacement of isotherms (often greater than 100 m). Seasonally, the current is hemmed into the coast during the fall by a full depth Atlantic Water layer that has penetrated onto the inner shelf. The Polar Water layer in the current then thickens through the winter and spring seasons increasing the freshwater content in the current; the timing implies that this is probably driven by the seasonally varying export of freshwater from the Arctic and not the local runoff from Greenland. The measured synoptic <span class="hlt">variability</span> is enhanced during the winter and spring period due to a lower halocline and a concurrent enhancement in the along-coast wind speed. The local winds force much of the high-frequency <span class="hlt">variability</span> in a manner consistent with downwelling, but <span class="hlt">variability</span> distinct from downwelling is also visible.</p> <div class="credits"> <p class="dwt_author">Harden, B. E.; Straneo, F.; Sutherland, D. A.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-12-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">348</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2013AJ....145...79C"> <span id="translatedtitle">Precise High-cadence Time Series <span class="hlt">Observations</span> of Five <span class="hlt">Variable</span> Young Stars in Auriga with MOST</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">To explore young star <span class="hlt">variability</span> on a large range of timescales, we have used the MOST satellite to obtain 24 days of continuous, sub-minute cadence, high-precision optical photometry on a field of classical and weak-lined T Tauri stars (TTSs) in the Taurus-Auriga star formation complex. <span class="hlt">Observations</span> of AB Aurigae, SU Aurigae, V396 Aurigae, V397 Aurigae, and HD 31305 reveal brightness fluctuations at the 1%-10% level on timescales of hours to weeks. We have further assessed the <span class="hlt">variability</span> properties with Fourier, wavelet, and autocorrelation techniques, identifying one significant period per star. We present spot models in an attempt to fit the periodicities, but find that we cannot fully account for the <span class="hlt">observed</span> <span class="hlt">variability</span>. Rather, all stars exhibit a mixture of periodic and aperiodic behavior, with the latter dominating stochastically on timescales less than several days. After removal of the main periodicity, periodograms for each light curve display power-law trends consistent with those seen for other young accreting stars. Several of our targets exhibited unusual <span class="hlt">variability</span> patterns not anticipated by prior studies, and we propose that this behavior originates with the circumstellar disks. The MOST <span class="hlt">observations</span> underscore the need for investigation of TTS light variations on a wide range of timescales in order to elucidate the physical processes responsible; we provide guidelines for future time series <span class="hlt">observations</span>. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Systems Canada Inc. (MSCI), formerly part of Dynacon, Inc., the University of Toronto Institute for Aerospace Studies, and the University of British Columbia with the assistance of the University of Vienna.</p> <div class="credits"> <p class="dwt_author">Cody, Ann Marie; Tayar, Jamie; Hillenbrand, Lynne A.; Matthews, Jaymie M.; Kallinger, Thomas</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-03-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">349</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/0812.2415v1"> <span id="translatedtitle"><span class="hlt">Observations</span> of the cataclysmic <span class="hlt">variable</span> SDSS J081321.91+452809.4</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">Our <span class="hlt">observations</span> of the first reported outburst of SDSS J081321.91+452809.4 during 2008 April show that this cataclysmic <span class="hlt">variable</span> is a dwarf nova. The outburst amplitude was at least 3.1 magnitudes and the outburst appears to have been rather short-lived at around 3 days with a rapid decline to quiescence of 0.73 mag/day.</p> <div class="credits"> <p class="dwt_author">Jeremy Shears; Ian Miller; Steve Brady</p> <p class="dwt_publisher"></p> <p class="publishDate">2008-12-12</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">350</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://academic.research.microsoft.com/Publication/52788850"> <span id="translatedtitle">VRc <span class="hlt">observations</span> of LMC long-period red <span class="hlt">variables</span> (Noda+, 2002)</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">146 long-period red <span class="hlt">variable</span> stars in the Large Magellanic Cloud (LMC) from the three-year Microlensing <span class="hlt">Observations</span> in Astrophysics (MOA) project data base were analysed. A careful periodic analysis was performed on these stars and a catalogue of their magnitudes, colours, periods and amplitudes is presented. We convert our blue and red magnitudes to K-band values using 19 oxygen-rich stars. A</p> <div class="credits"> <p class="dwt_author">S. Noda; M. Takeuti; F. Abe; I. A. Bond; R. J. Dodd; J. B. Hearnshaw; M. Honda; M. Honma; J. Jugaku; S. Kabe; Y. Kan-Ya; Y. Kato; P. M. Kilmartin; Y. Matsubara; K. Masuda; Y. Muraki; T. Nakamura; G. R. Nankivell; C. Noguchi; K. Ohnishi; M. Reid; N. J. Rattenbury; T. Saito; H. Sato; M. Sekiguchi; J. Skuljan; D. J. Sullivan; T. Sumi; Y. Watase; S. Wilkinson; R. Yamada; T. Yanagisawa; P. C. M. Yock; M. Yoshizawa</p> <p class="dwt_publisher"></p> <p class="publishDate">2002-01-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">351</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ApJ...793...26P"> <span id="translatedtitle">The <span class="hlt">Variable</span> Hard X-Ray Emission of NGC 4945 as <span class="hlt">Observed</span> by NuSTAR</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">We present a broadband (~0.5-79 keV) spectral and temporal analysis of multiple NuSTAR <span class="hlt">observations</span> combined with archival Suzaku and Chandra data of NGC 4945, the brightest extragalactic source at 100 keV. We <span class="hlt">observe</span> hard X-ray (>10 keV) flux and spectral <span class="hlt">variability</span>, with flux variations of a factor of two on timescales of 20 ks. A <span class="hlt">variable</span> primary continuum dominates the high-energy spectrum (>10 keV) in all states, while the reflected/scattered flux that dominates at E <10 keV stays approximately constant. From modeling the complex reflection/transmission spectrum, we derive a Compton depth along the line of sight of ?Thomson ~ 2.9, and a global covering factor for the circumnuclear gas of ~0.15. This agrees with the constraints derived from the high-energy <span class="hlt">variability</span>, which implies that most of the high-energy flux is transmitted rather than Compton-scattered. This demonstrates the effectiveness of spectral analysis at constraining the geometric properties of the circumnuclear gas, and validates similar methods used for analyzing the spectra of other bright, Compton-thick active galactic nuclei (AGNs). The lower limits on the e-folding energy are between 200 and 300 keV, consistent with previous BeppoSAX, Suzaku, and Swift Burst Alert Telescope <span class="hlt">observations</span>. The accretion rate, estimated from the X-ray luminosity and assuming a bolometric correction typical of type 2 AGN, is in the range ~0.1-0.3 ?Edd depending on the flux state. The substantial <span class="hlt">observed</span> X-ray luminosity <span class="hlt">variability</span> of NGC 4945 implies that large errors can arise from using single-epoch X-ray data to derive L/L Edd values for obscured AGNs.</p> <div class="credits"> <p class="dwt_author">Puccetti, Simonetta; Comastri, Andrea; Fiore, Fabrizio; Arévalo, Patricia; Risaliti, Guido; Bauer, Franz E.; Brandt, William N.; Stern, Daniel; Harrison, Fiona A.; Alexander, David M.; Boggs, Steve E.; Christensen, Finn E.; Craig, William W.; Gandhi, Poshak; Hailey, Charles J.; Koss, Michael J.; Lansbury, George B.; Luo, Bin; Madejski, Greg M.; Matt, Giorgio; Walton, Dominic J.; Zhang, Will</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-09-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">352</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ncbi.nlm.nih.gov/pubmed/23162165"> <span id="translatedtitle">The three-class ideal <span class="hlt">observer</span> for univariate normal data: Decision <span class="hlt">variable</span> and ROC surface properties.</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p class="result-summary">Although a fully general extension of ROC analysis to classification tasks with more than two classes has yet to be developed, the potential benefits to be gained from a practical performance evaluation methodology for classification tasks with three classes have motivated a number of research groups to propose methods based on constrained or simplified <span class="hlt">observer</span> or data models. Here we consider an ideal <span class="hlt">observer</span> in a task with underlying data drawn from three univariate normal distributions. We investigate the behavior of the resulting ideal <span class="hlt">observer</span>'s decision <span class="hlt">variables</span> and ROC surface. In particular, we show that the pair of ideal <span class="hlt">observer</span> decision <span class="hlt">variables</span> is constrained to a parametric curve in two-dimensional likelihood ratio space, and that the decision boundary line segments used by the ideal <span class="hlt">observer</span> can intersect this curve in at most six places. From this, we further show that the resulting ROC surface has at most four degrees of freedom at any point, and not the five that would be required, in general, for a surface in a six-dimensional space to be non-degenerate. In light of the difficulties we have previously pointed out in generalizing the well-known area under the ROC curve performance metric to tasks with three or more classes, the problem of developing a suitable and fully general performance metric for classification tasks with three or more classes remains unsolved. PMID:23162165</p> <div class="credits"> <p class="dwt_author">Edwards, Darrin C; Metz, Charles E</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-08-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">353</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.osti.gov/scitech/biblio/22131027"> <span id="translatedtitle">THE <span class="hlt">VARIABLE</span> OPTICAL POLARIZATION AND FERMI <span class="hlt">OBSERVATIONS</span> OF PMN J0948+0022</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p class="result-summary">We report on <span class="hlt">observations</span> of the {gamma}-ray and optical photopolarimetric behavior of the radio-loud, narrow-line type-1 Seyfert galaxy PMN J0948+0022 over a 27 month period. As this object has recently been suggested to represent a prototype of an emerging class of blazar-like objects, the <span class="hlt">observed</span> properties are compared to those of blazars. We extract doubling timescales of roughly 4 hr for the optical and {gamma}-ray bands. The rapid microvariability in the optical/near-IR, significant and <span class="hlt">variable</span> optical polarization, and strong yet rapidly <span class="hlt">variable</span> {gamma}-ray emission we <span class="hlt">observe</span> for PMN J0948+0022 are all classical <span class="hlt">observational</span> characteristics associated with blazars. However, since these <span class="hlt">observations</span> do not show a clear correlation between the {gamma}-ray and optical behavior, they do not offer conclusive proof that the emissive behavior of PMN J0948+0022 is due to a relativistic jet oriented close to our line of sight.</p> <div class="credits"> <p class="dwt_author">Eggen, Joseph R.; Miller, H. Richard; Maune, Jeremy D., E-mail: eggen@chara.gsu.edu [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303-3083 (United States)</p> <p class="dwt_publisher"></p> <p class="publishDate">2013-08-20</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">354</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014PhDT........26J"> <span id="translatedtitle">Split-beam echosounder <span class="hlt">observations</span> of natural methane seep <span class="hlt">variability</span> in the northern Gulf of Mexico</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">A method for positioning and characterizing marine gas seeps using an 18-kHz scientific split-beam echosounder (SBES) was developed and applied to SBES data collected in the northern Gulf of Mexico. A total of 161 plumes of presumed methane gas bubbles originating at approximately 1400 m depth were <span class="hlt">observed</span> over 27 repeat surveys and grouped by proximity into 35 clusters. Profiles of mean target strength per vertical meter were calculated with compensation for SBES beam pattern and geometry of plume axis ensonification. These profiles were used as indicators of the fluxes and fates of gas bubbles acoustically <span class="hlt">observable</span> at 18 kHz and showed significant <span class="hlt">variability</span> between repeat <span class="hlt">observations</span> at time intervals of 1 hour to 7.5 months. The minimum depths of acoustic plume <span class="hlt">observations</span> averaged 875 m and frequently coincided with increased reverberation in layers of biological scatterers. Minimum depth estimates were limited by the SBES beam pattern in five instances.</p> <div class="credits"> <p class="dwt_author">Jerram, Kevin</p> <p class="dwt_publisher"></p> <p class="publishDate"></p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">355</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3434316"> <span id="translatedtitle">Inter-<span class="hlt">observer</span> <span class="hlt">Variability</span> in Esophageal Body Measurements with High Resolution Manometry among New Physician Users</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Goals To evaluate inter-<span class="hlt">observer</span> <span class="hlt">variability</span> among four new physician users on measures of esophageal body function. Background Esophageal high resolution manometry (HRM) allows <span class="hlt">observation</span> of esophageal motility via pressure topography plots. Little is known about the inter-<span class="hlt">observer</span> <span class="hlt">variability</span> among physicians. Study Two resident and two fellow level physicians each interpreted 10 liquid swallows of 20 esophageal HRM studies (n=200 swallows) using the BioVIEW Analysis Suite (Sandhill Scientific, Inc.). Studies evaluated were from patients referred for evaluation of dysphagia but found to have normal esophageal manometry and complete liquid bolus transit. Physicians received an orientation session and reviewed recent literature. Each physician recorded contractile front velocity (CFV) and distal contractile integral (DCI) for each liquid swallow. STATISTICS: Inter-<span class="hlt">observer</span> agreements for CFV and DCI were assessed by intraclass correlation (ICC) values. Linear correlations between measurements by two readers were assessed using linear regression modeling techniques. Results CFV and DCI values of up to 200 data points were analyzed. Four reader results for CFV and DCI showed strong agreement although stronger for DCI measures (ICC=0.94; 0.91 - 0.98) in comparison to CFV (ICC=0.79; 0.52 - 0.82). Further correlation was performed with two readers; readers 1 and 2 revealed excellent correlation for DCI (r=0.95, p<0.001) and good correlation for CFV (r=0.61, p<0.001). Conclusions With a thorough orientation session, good to excellent agreement for CFV and DCI measurements can be obtained from new physician users. CFV measures exhibit greater inter-<span class="hlt">observer</span> <span class="hlt">variability</span> possibly due to the artifact produced by intraesophageal pressurization. PMID:22647828</p> <div class="credits"> <p class="dwt_author">Singh, Erick; Rife, Christopher; Clayton, Steven; Naas, Peter; Nietert, Paul; Castell, Donald</p> <p class="dwt_publisher"></p> <p class="publishDate">2012-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">356</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://adsabs.harvard.edu/abs/2014ACP....1410589D"> <span id="translatedtitle">Summertime tropospheric-ozone <span class="hlt">variability</span> over the Mediterranean basin <span class="hlt">observed</span> with IASI</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p class="result-summary">The Mediterranean basin is one of the most sensitive regions in the world regarding climate change and air quality. This is partly due to the singular dynamical situation of the Mediterranean basin that leads to tropospheric-ozone concentrations that are among the highest over the Northern Hemisphere. Six years of summertime tropospheric ozone <span class="hlt">observed</span> by the Infrared Atmospheric Sounding Interferometer (IASI) instrument from 2007 to 2012 have been analysed to document the <span class="hlt">variability</span> of ozone over this region. The satellite <span class="hlt">observations</span> have been examined together with meteorological analyses (from ECMWF) to understand the processes driving this <span class="hlt">variability</span>. Our work confirmed the presence of a steep west-east ozone gradient in the lower troposphere with the highest concentrations <span class="hlt">observed</span> over the eastern part of the Mediterranean basin. This gradient is mainly explained by diabatic convection over the Persian Gulf during the Indian monsoon season, which induces an important subsidence of ozone-rich air masses from the upper to the lower troposphere over the central and the eastern Mediterranean basin. IASI <span class="hlt">observations</span> of ozone concentrations at a 3 km height show a clear summertime maximum in July that is well correlated to the maximum of downward transport of ozone-rich air masses from the upper troposphere. Even if this feature is robust over the six analysed years, we have also investigated monthly ozone anomalies - one positive (June 2008) and one negative (June and July 2009) - using daily IASI <span class="hlt">observations</span>. We show that the relative position and the strength of the meteorological systems (Azores anticyclone and Middle Eastern depression) present over the Mediterranean are key factors in explaining both the <span class="hlt">variability</span> and the anomalies of ozone in the lower troposphere in this region.</p> <div class="credits"> <p class="dwt_author">Doche, C.; Dufour, G.; Foret, G.; Eremenko, M.; Cuesta, J.; Beekmann, M.; Kalabokas, P.</p> <p class="dwt_publisher"></p> <p class="publishDate">2014-10-01</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">357</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4227093"> <span id="translatedtitle"><span class="hlt">Variability</span> of linezolid concentrations after standard dosing in critically ill patients: a prospective <span class="hlt">observational</span> study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Introduction Severe infections in intensive care patients show high morbidity and mortality rates. Linezolid is an antimicrobial drug frequently used in critically ill patients. Recent data indicates that there might be high <span class="hlt">variability</span> of linezolid serum concentrations in intensive care patients receiving standard doses. This study was aimed to evaluate whether standard dosing of linezolid leads to therapeutic serum concentrations in critically ill patients. Methods In this prospective <span class="hlt">observational</span> study, 30 critically ill adult patients with suspected infections received standard dosing of 600 mg linezolid intravenously twice a day. Over 4 days, multiple serum samples were obtained from each patient, in order to determine the linezolid concentrations by liquid chromatography tandem mass spectrometry. Results A high <span class="hlt">variability</span> of serum linezolid concentrations was <span class="hlt">observed</span> (range of area under the linezolid concentration time curve over 24 hours (AUC24) 50.1 to 453.9 mg/L, median 143.3 mg*h/L; range of trough concentrations (Cmin)?<?0.13 to 14.49 mg/L, median 2.06 mg/L). Furthermore, potentially subtherapeutic linezolid concentrations over 24 hours and at single time points (defined according to the literature as AUC24?<?200 mg*h/L and Cmin?<?2 mg/L) were <span class="hlt">observed</span> for 63% and 50% of the patients, respectively. Finally, potentially toxic levels (defined as AUC24?>?400 mg*h/L and Cmin?>?10 mg/L) were <span class="hlt">observed</span> for 7 of the patients. Conclusions A high <span class="hlt">variability</span> of linezolid serum concentrations with a substantial percentage of potentially subtherapeutic levels was <span class="hlt">observed</span> in intensive care patients. The findings suggest that therapeutic drug monitoring of linezolid might be helpful for adequate dosing of linezolid in critically ill patients. Trial registration Clinicaltrials.gov NCT01793012. Registered 24 January 2013. PMID:25011656</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2014-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">358</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://arxiv.org/pdf/astro-ph/9812161v1"> <span id="translatedtitle">Multiwavelength <span class="hlt">Observations</span> of GX 339-4 in 1996. II. Rapid X-ray <span class="hlt">Variability</span></span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.osti.gov/eprints/">E-print Network</a></p> <p class="result-summary">As part of our multiwavelength campaign of GX 339-4 <span class="hlt">observations</span> in 1996 we present the rapid X-ray <span class="hlt">variability</span> <span class="hlt">observed</span> July 26 using the RXTE when the source was in a hard state (= soft X-ray low state). We found that the source was extremely <span class="hlt">variable</span>, with many bright flares. The flares have relatively symmetric time profiles. There are a few time intervals where the flux rises steadily and then drops suddenly, sometimes to a level lower than the average before the increase. Hardness ratios showed that the source was slightly softer when the flux was brighter. The power density spectra (PDS) were also complicated and we found that broken power laws do not provide adequate fits to any of them. Instead a pair of zero-centered Lorentzians gives a good general description of the shape of the PDS. We found several quasi-periodic oscillations (QPO), including some that are harmonically spaced with the most stable frequency at 0.35 Hz. While the overall rms <span class="hlt">variability</span> of the source was close to being constant throughout the <span class="hlt">observation</span> (29% integrating between 0.01 and 50 Hz), there is a small but significant change in the PDS shape with time. More importantly, we show that the soft 2-5 keV band is more <span class="hlt">variable</span> than the harder 5-10 and 10-40 keV bands, which is unusual for this source and for other black hole candidates. Cross correlation functions (CCF) between these bands show that the light curve for the 10-40 keV band lags that of the 2-5 keV band by 5 msec.</p> <div class="credits"> <p class="dwt_author">I. A. Smith; E. P. Liang</p> <p class="dwt_publisher"></p> <p class="publishDate">1998-12-08</p> </div> </div> </div> </div> <div class="floatContainer result odd" lang="en"> <div class="resultNumber element">359</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.ess.uci.edu/~gudrun/papers/PDO.pdf"> <span id="translatedtitle">The Role of Tropospheric Rossby Wave Breaking in the Pacific <span class="hlt">Decadal</span> Oscillation</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://academic.research.microsoft.com/">Microsoft Academic Search </a></p> <p class="result-summary">The leading pattern of extratropical Pacific sea surface temperature <span class="hlt">variability</span> (the Pacific <span class="hlt">decadal</span> oscil- lation (PDO)) is shown to depend on <span class="hlt">observed</span> <span class="hlt">variability</span> in the spatiotemporal distribution of tropospheric Rossby wave breaking (RWB), where RWB is the irreversible overturning of potential vorticity on isentropic surfaces. Composite analyses based on hundreds of RWB cases show that anticyclonic (cyclonic) RWB is associated</p> <div class="credits"> <p class="dwt_author">Courtenay Strong; Gudrun Magnusdottir</p> <p class="dwt_publisher"></p> <p class="publishDate">2009-01-01</p> </div> </div> </div> </div> <div class="floatContainer result " lang="en"> <div class="resultNumber element">360</div> <div class="resultBody element"> <p class="result-title"><a target="resultTitleLink" href="http://science.gov/scigov/link.html?type=RESULT&redirectUrl=http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2987974"> <span id="translatedtitle"><span class="hlt">Variability</span> of indication criteria in knee and hip replacement: an <span class="hlt">observational</span> study</span></a>  </p> <div class="result-meta"> <p class="source"><a target="_blank" id="logoLink" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p class="result-summary">Background Total knee (TKR) and hip (THR) replacement (arthroplasty) are effective surgical procedures that relieve pain, improve patients' quality of life and increase functional capacity. Studies on variations in medical practice usually place the indications for performing these procedures to be highly <span class="hlt">variable</span>, because surgeons appear to follow different criteria when recommending surgery in patients with different severity levels. We therefore proposed a study to evaluate inter-hospital <span class="hlt">variability</span> in arthroplasty indication. Methods The pre-surgical condition of 1603 patients included was compared by their personal characteristics, clinical situation and self-perceived health status. Patients were asked to complete two health-related quality of life questionnaires: the generic SF-12 (Short Form) and the specific WOMAC (Western Ontario and Mcmaster Universities) scale. The type of patient undergoing primary arthroplasty was similar in the 15 different hospitals evaluated. The <span class="hlt">variability</span> in baseline WOMAC score between hospitals in THR and TKR indication was described by range, mean and standard deviation (SD), mean and standard deviation weighted by the number of procedures at each hospital, high/low ratio or extremal quotient (EQ5-95), variation coefficient (CV5-95) and weighted variation coefficient (WCV5-95) for 5-95 percentile range. The <span class="hlt">variability</span> in subjective and objective signs was evaluated using median, range and WCV5-95. The appropriateness of the procedures performed was calculated using a specific threshold proposed by Quintana et al for assessing pain and functional capacity. Results The <span class="hlt">variability</span> expressed as WCV5-95 was very low, between 0.05 and 0.11 for all three dimensions on WOMAC scale for both types of procedure in all participating hospitals. The <span class="hlt">variability</span> in the physical and mental SF-12 components was very low for both types of procedure (0.08 and 0.07 for hip and 0.03 and 0.07 for knee surgery patients). However, a moderate-high <span class="hlt">variability</span> was detected in subjective-objective signs. Among all the surgeries performed, approximately a quarter of them could be considered to be inappropriate. Conclusions A greater inter-hospital <span class="hlt">variability</span> was <span class="hlt">observed</span> for objective than for subjective signs for both procedures, suggesting that the differences in clinical criteria followed by surgeons when indicating arthroplasty are the main responsible factors for the variation in surgery rates. PMID:20977745</p> <div class="credits"> <p class="dwt_author"></p> <p class="dwt_publisher"></p> <p class="publishDate">2010-01-01</p> </div> </div> </div> </div> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_17");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onClick='return showDiv("page_16");' href="#">16</a> <a onClick='return showDiv("page_17");' href="#">17</a> <a style="font-weight: bold;">18</a> <a onClick='return showDiv("page_19");' href="#">19</a> <a onClick='return showDiv("page_20");' href="#">20</a> <a onClick='return showDiv("page_21");' href="#">21</a> <a onClick='return showDiv("page_22");' href="#">22</a> <a onClick='return showDiv("page_23");' href="#">23</a> <a onClick='return showDiv("page_24");' href="#">24</a> <a onClick='return showDiv("page_25");' href="#">25</a> </span> </span> <a id="NextPageLink" onclick='return showDiv("page_19");' href="#" title="Next Page"> <img id="NextPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.next.18x20.png" alt="Next Page" /></a> <a id="LastPageLink" onclick='return showDiv("page_25.0");' href="#" title="Last Page"> <img id="LastPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.last.18x20.png" alt="Last Page" /></a> </div> </div> </div><!-- page_18 div --> <div id="page_19" class="hiddenDiv"> <div id="filter_results_form" class="filter_results_form floatContainer" style="visibility: visible;"> <div style="width:100%" id="PaginatedNavigation" class="paginatedNavigationElement"> <a id="FirstPageLink" onclick='return showDiv("page_1");' href="#" title="First Page"> <img id="FirstPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.first.18x20.png" alt="First Page" /></a> <a id="PreviousPageLink" onclick='return showDiv("page_18");' href="#" title="Previous Page"> <img id="PreviousPageLinkImage" class="Icon" src="http://www.science.gov/scigov/images/icon.previous.18x20.png" alt="Previous Page" /></a> <span id="PageLinks" class="pageLinks"> <span> <a onClick='return showDiv("page_1");' href="#">1</a> <a onClick='return showDiv("page_2");' href="#">2</a> <a onClick='return showDiv("page_3");' href="#">3</a> <a onClick='return showDiv("page_4");' href="#">4</a> <a onClick='return showDiv("page_5");' href="#">5</a> <a onClick='return showDiv("page_6");' href="#">6</a> <a onClick='return showDiv("page_7");' href="#">7</a> <a onClick='return showDiv("page_8");' href="#">8</a> <a onClick='return showDiv("page_9");' href="#">9</a> <a onClick='return showDiv("page_10");' href="#">10</a> <a onClick='return showDiv("page_11");' href="#">11</a> <a onClick='return showDiv("page_12");' href="#">12</a> <a onClick='return showDiv("page_13");' href="#">13</a> <a onClick='return showDiv("page_14");' href="#">14</a> <a onClick='return showDiv("page_15");' href="#">15</a> <a onCl